Bushings and abrasive wheel therewith

A bushing is disclosed for use with a grinding abrasive flap wheel of the type employing circular end caps mounted on opposite sides of an annular array of abrasive leaves, wherein bases of the leaves are interconnected by an adhesive and have two notches in their opposite side edges near each base end of each leaf such that the notches form concentric circular depressions on opposite sides of the array and each end cap has an outer rim portion and an arcuate lip inwardly extending therefrom which engages the circular depressions formed by the notches thereby mechanically gripping the ends of the abrasive leaves.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a bushing for use with a grinding abrasive flap wheel having interleaved coated abrasive flaps.

2. Prior Art

Flap-type rotary abrasive devices having annular arrays of flexible abrasive leaves are commonly used in the abrasive finishing art. For economic reasons, conventional rotary abrasive devices consist of flexible leaves each comprising a piece of sheet material having abrasive particles bonded on one face thereof.

Fabrication of such a rotary device conventionally requires that the abrasive leaves have two notches in their opposite side edges near the base end of each leaf. As the leaves are arranged in an annular array, the notches form concentric circular depressions on opposite sides of the array.

Circular disks such as two metallic end caps mounted on opposite sides of the array are provided serve as reinforcement for the arrangement of leaves. Each end cap has an inwardly extending lip which engages the circular depressions thereby mechanically gripping the inner ends of the abrasive leaves. An adhesive is commonly introduced into contact with the leaves at their base ends to bond them into a unitary core.

The design of abrasive configurations has varied somewhat, but the basic elements remain similar for manufacturing and cost reasons. A significant problem which exists with such abrasive flap devices is that the flaps tend to blow out prematurely during use. This is typically due to a slight bowing in the flaps which results from pressure exerted on a bearing surface surrounding a central opening of hubs of the end caps which over time disfigures the end cap. This effect is illustrated in FIG.2. Traditional designs run a drive shaft through the hubs of the end caps with the caps being locked in place on the shaft by nut. Thus, the hubs bear significant force during use.

The present invention discloses bushings for use with a grinding abrasive flap wheel. By so providing, the present invention overcomes the deficiencies in the art and further reduces the cost of manufacture of abrasive flap wheels while increasing the life thereof

SUMMARY OF THE INVENTION

It is an object to reduce the cost of manufacturing grinding abrasive flap wheel.

It is a further object to increase the life of a grinding abrasive flap wheel without the need to significantly depart of conventional design.

It is still another object to provide a bushing for use with a grinding abrasive flap wheel.

It is another object to provide an improved abrasive wheel.

Accordingly, the present invention is directed to a bushing for use with a grinding abrasive flap wheel of the type employing circular end caps mounted on opposite sides of an annular array of abrasive leaves, wherein bases of the leaves are interconnected by an adhesive and have two notches in their opposite side edges near each base end of each leaf such that the notches form concentric circular depressions on opposite sides of the array and each end cap has an outer rim portion and an arcuate lip inwardly extending therefrom which engages the circular depressions formed by the notches thereby mechanically gripping the ends of the abrasive leaves.

The bushing includes a rigid disk member having an outer diameter formed with an laterally extending lip which is configured to at least partially seat within a concave portion of the arcuate lip and engage the rim portion of the end cap. The bushing includes a central hub having a central opening which cooperatively aligns with a central opening of the end cap to receive a drive shaft therethrough. The hub of the bushing can include an axially extending collar portion which has an outer diameter slightly less than the central opening of the end cap to be slidably received therethrough.

An annular inner surface of the bushing extends from the collar to the inwardly extending lip and is disposed adjacent an outer surface of the end cap. Preferably, an inwardly disposed portion of the annular inner surface is recessed such that an outer portion generally serves as a contacting surface portion with the outer surface of the end cap. Another aspect of the invention is to provide a high torque abrasive wheel and bushings.

Additionally, the bushing can include one or more bores which extend inwardly from an outer surface thereof. The bores are preferably radially equidistantly spaced for balance and aid in placement of the bushing to and from the end cap.

An important advantage of the invention is that laterally extending lip and contacting surface portion of the inner surface of the bushing becomes a retaining surface on the end cap with the retention force being applied to the rim of the end cap. In other words, the significant driving force being applied to the end cap during use has been shifted from the inner weaker bearing surface to the stronger outer rim portion of the end cap. The invention also provides for enhanced torque capability. This substantially precludes the bowing tendency which would normally occur through a nut and bolt clamping effect at the central portion of the end cap.

Other objects and advantages will become apparent from reading the specification in view of the drawings attached hereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, the bushing(s) of the present invention are generally referred to by the numeral10and are depicted for use with an abrasive flap wheel12. There are two bushings10depicted, but the description refers to the singular. The bushing10includes a rigid disk14which can be made of metal such as stainless steel or other suitable durable material and is preferably of a significant mass to further aid in carrying out the purpose of the present invention. In order to more fully describe the bushing10, the flap wheel will first be described.

The abrasive flap wheel12includes a pair of circular end caps13and15mounted on opposite sides of an annular array of abrasive leaves16. Each leaf16includes base18and the bases18of the leaves16are interconnected by an adhesive material20of the type well known to the art. Each leaf has two notches22and24in its opposite side edges26and28, respectively, near each end of base18of each leaf16.

When the leaves16are disposed in an annular array as seen inFIG. 5, for example, the notches22and24form concentric circular depressions on opposite sides of the array. Each end cap13and15has an outer rim portion17and19, respectively, and an arcuate lip21and23, respectively, extending inwardly therefrom which engages the circular depressions formed by notches22and24, as seen inFIG. 4, thereby mechanically gripping the ends of the abrasive leaves16when in disposed in their operative position, for example. Further, the end caps13and15include a central open surface27and29, respectively, which is modified from that of conventional end caps in that the open surfaces27and29are larger reasons which will be more fully understood hereinafter.

For purposes of simplifying the description, the bushing10will be described with reference to connection to one end cap13, with the understanding that like connection is obtained to end cap15. The bushing10has an outer diameter portion30formed with an laterally extending lip32which is configured to at least partially seat within a concave portion31of the arcuate lip21and engage the rim portion17of the end cap13. The bushing10includes a central hub34having a central open surface36which cooperatively coaxially aligns with the central open surface27of the end cap13.

The hub34of the bushing10includes an axially extending collar38which has an outer diameter slightly less than the central open surface27of the end cap13to be slidably received therethrough. The open surface27does not serve as a primary bearing surface.

An annular inner surface40of the bushing10extends from the collar38to the laterally extending lip32and is disposed adjacent an outer surface41of the end cap13. Preferably, an inwardly disposed portion42of the annular inner surface40is recessed such that an outer portion44generally serves as a contacting surface portion with the outer surface41of the end cap13.

Thus, the surfaces41and lip portion32are bearing surfaces of the bushing10such that when the end caps13and15are connected and drawn together by means of drive shaft DS and nut N. The rim portion17and19aid to prevent galling between the surface27and collar38which could otherwise occur without the redirection of the retaining and driving mechanism employed with the aid of the invention. The open surface36receives drive shaft DS therethrough which has a threaded end and nut N can be threaded to the drive shaft DS to draw the bushing10into to frictional engagement with the end cap17. The drive shaft DS can be gripped by a chuck of a pneumatic motor or by any other commonly used power driving device.

In operation, the drive shaft DS is rotated in the direction in which the abrasive sides of the leaves16face. It is important that the annular array of leaves16rotate at a high angular velocity in order that rapid abrasion can be effected. This high angular velocity creates a significant centrifugal force outwardly, thereby requiring that the leaves16be securely fastened so that the array will not come apart during operation. According to the present invention, this is more readily achieved by the use of the bushing10which aids to maintain proper leaf position during operation.

Additionally, the bushing10can include one or more bores46which extend inwardly from an outer surface48through the inner surface40. The bores46are preferably radially equidistantly spaced for balance and serve to aid in placement on as well as removal of the bushing10to the end cap17.

Applicant has discovered that by providing the bushing and abrasive wheel combination of the present invention, there is an unexpected increase in performance of the wheel, recognizable by a significant increase in grain efficiency. It is to be recognized that other bushing and end cap configurations carrying out the purpose of the invention could be utilized. Accordingly, the specific embodiment disclosed is representative in providing a basis for the claims which define the scope of the present invention.