Dentistry – Apparatus – Having motor or means to transmit motion from motor to tool
Reexamination Certificate
1999-02-17
2001-02-20
Wilson, John J. (Department: 3732)
Dentistry
Apparatus
Having motor or means to transmit motion from motor to tool
Reexamination Certificate
active
06190168
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a dental handpiece for retaining a conventional dental bur or similar workpiece and to an improved release means by which the bur can be easily removed from the handpiece while minimizing the manual pushing force that is necessary to actuate the release means.
2. Background Art
Compressed air driven dental handpieces have long been used by dental workers to treat the teeth of their patients. One of a variety of workpieces (e.g. a dental bur) is releasably connected to a hollow cylindrical collet of the handpiece so as to be rotatable in response to a corresponding rotational force that is applied to the collet.
From time-to-time, it is necessary to remove the dental bur from the handpiece for purposes of repair, cleaning or replacement by a different workpiece. To accomplish the foregoing, the dental worker typically exerts a pushing force against a push-button of the handpiece which is ultimately transmitted to the collet so as to cause the collet to release its grip on the bur. However, it has been found that a large pushing force is often required before the bur will be released by the collet. Such a large pushing force has heretofor been necessary because of the shape of a collet actuator of the handpiece that transmits the pushing force from the push-button to the collet. More particularly, one well known collet actuator has a pair of wedge-shaped tips that form relatively large angles of about 30 degrees. The collet actuator is moved axially by the push-button so that the wedge shaped tips thereof are received by the hollow cylindrical collet to cause flexible clamping fingers of a collet to rotate outwardly and thereby release their grip upon the bur.
As a consequence of the large angle of the wedge-shaped tips of the collet actuator and the large pushing force that is transmitted to the collet, the flexible clamping fingers of the collet have been known to rotate through a correspondingly large arc. On occasion, this large rotation has significantly reduced the spring-like memory of the flexible clamping fingers of the collet. In this case, the collet may become deformed which undesirably effects its ability to reliably retain a dental workpiece between the flexible clamping fingers. Accordingly, it may be necessary to repair the dental handpiece and/or replace the collet which increases both the cost and downtime to the dental worker.
What is needed is a dental handpiece having an improved workpiece (e.g. bur) release means that reduces the manual pushing force required to release the workpiece as well as the likelihood that the collet will be deformed as the workpiece is released.
SUMMARY OF THE INVENTION
In general terms, a compressed air driven dental handpiece is disclosed having improved bur (or other dental workpiece) release means. The bur is releasably secured between a pair of opposing clamping fingers that are separated from one another by a pair of slots formed through the proximal end of a hollow cylindrical collet. The clamping fingers are characterized by a spring-like memory and the ability to rotate outwardly and away from one another to release their grip on the bur. A collet actuator is held by a compression spring in spaced axial alignment with the collet. The actuator has a pair of wedge-shaped tips that are aligned for receipt by respective ones of a pair of slots at the proximal end of the collet. As an important detail of this invention, each of the wedge-shaped tips forms a relatively narrow angle of about 22 degrees. Both the collet and the collet actuator are surrounded by a cylindrical spindle. The collet is staked to the interior of the spindle, while the collet actuator is adapted to slide reciprocally through the spindle relative to the collet.
In operation, the dental worker applies an axial pushing force to a push-button of the handpiece. The pushing force is transferred from the push-button to the collet actuator, whereupon the actuator is caused to slide through the spindle and towards the collet. Accordingly, the pair of wedge-shaped tips of the actuator move through the respective slots at the proximal end of the collet in order to stress the flexible clamping fingers of the collet and cause the compression spring to be compressed and store energy. The flexible fingers of the collet are now rotated outwardly and away from one another so as to be displaced through a stroke gap of about 0.004 inches to strike the cylindrical spindle. At this point, the dental bur may be easily removed from the distal end of the collet.
By virtue of the narrow angle of the wedge-shaped tips of the collet actuator, the pushing force initially applied to the push-button to move the tips through the slots of the collet to stress the flexible clamping fingers thereof is reduced. What is more, by rotating the flexible clamping fingers of the collet into contact with the spindle, the arc through which the fingers rotate is controlled (i.e. limited) so as to prevent the possible loss of the spring-like memory of the flexible fingers and a deformation of the collet.
When the pushing force applied to the push-button is removed, the compression spring will expand and release energy. The collet actuator is then driven through the spindle away from the collet, such that the wedge-shaped tips of the actuator are withdrawn from the slots at the proximal end of the collet. The spring-like memory of the flexible clamping fingers now causes the fingers to automatically rotate inwardly and towards one another so as to move back to their initial unstressed position at which to clamp the same or a different workpiece therebetween.
REFERENCES:
patent: 4874314 (1989-10-01), Fleer et al.
patent: 5040980 (1991-08-01), Heil
Fischer Morland C.
Wilson John J.
LandOfFree
Dental handpiece having improved bur release means does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dental handpiece having improved bur release means, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dental handpiece having improved bur release means will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2599604