Patent Application
20070126188
1. Field of the Invention
Example, non-limiting embodiments of the present invention relate in general to tool chucks for attachment of accessories to power drivers, and more particularly to a tool chuck having a spacer.
2. Description of Related Art
Tool chucks may be actuated (to open and close the chuck jaws) via a power take off (“PTO”) feature. Tool chucks with various PTO features are described in commonly-assigned, copending application Ser. No. 11/400,378 filed Apr. 10, 2006 (the “'378 application”). The entire contents of the '378 application are incorporated herein by reference.
A rolling element bearing 715 may be provided between the input shaft 60 and the chuck actuating shaft 64 to facilitate a relative rotation between these component parts. A relative rotation between the input shaft 60 and the chuck actuating shaft 64 may occur when the tool chuck 50 is operated in a MANUAL OVERRIDE MODE and/or a CHUCK MODE (for example), as described in the '378 application.
Although the rolling element bearing 75 is generally thought to provide acceptable performance, it is not without shortcomings. For example, axial thrust loads may be applied to the rolling element bearing 75 when the power driver provides a. hammer feature. Such axial thrust loads may cause high contact stresses to develop in the rolling elements (e.g., ball, pins, etc.) of the rolling element bearing 75. The axial thrust loads (rind the associated contact stresses) may shorten the life of the rolling element bearing 75.
According to an example, non-limiting embodiment, a tool chuck may include an input shaft. A chuck actuating shaft may be mounted for rotation on the input shaft. A chuck actuating screw may be coupled to the chuck actuating shaft. A spacer may be interposed between the chuck actuating shaft and the input shaft. No rolling elements may be interposed between the chuck actuating shaft and the input shaft.
According to another example, non-limiting embodiment, a tool chuck may include an input shaft. A chuck actuating shaft may be mounted for rotation on the input shaft. A chuck actuating screw may be coupled to the chuck actuating shaft. A spacer, without rolling elements, may be interposed between the chuck actuating shaft and the input shaft.
The above and other features, including various and novel details of construction and combinations of parts will be more particularly described with reference to the accompanying drawings. It will be understood that the details of the example embodiments are shown by way of illustration only and not as limitations of the invention. The principles and features of this invention may be employed in varied and numerous embodiments without departing from the scope of the invention.
The example tool chuck 150 depicted in
The spacer 175 may not include any rolling elements. In this example embodiment, the spacer 175 may be a solid body having a washer shape, as shown in
By way of example only, the spacer 175 may be fabricated from numerous and varied polymer materials inclusive of (but not limited to) thermoplastic alloys, thermosetting alloys and/or polymer blends. Such materials may be selected based on characteristics such as compressive strength, coefficient of friction and/or wear characteristics. For example, a suitable polymer spacer 175 may have a compressive strength of greater than about 3,000 psi, a coefficient of static friction of less than about 0.3μ, and/or wear characteristics such that no appreciable dimensional changes (e.g., thinning) occur over the life cycle of the power driver. Polymer spacers sold under the IGLIDE® line by Igus Inc. have been suitably implemented.
In the example, non-limiting embodiment, the spacer 175 may be implemented for dry operation. Here, a solid lubricant may be distributed throughout the thickness of the spacer 175. The spacer 175 may have a solid body construction.
In alternative embodiments, the spacer 175 may be implemented for wet operation. Here, a liquid lubricant may be applied to the spacer 175. The spacer 175 may have voids for accommodating the liquid lubricant.
In alternative embodiments, the spacer 175 may have a laminated. structure. For example, the spacer 175 may include a more elastic inner layer, and harder outer layers having the desired compressive strength, coefficient of friction and/or wear characteristics. A laminated structure may be suitably implemented for wet and dry operations, as desired.
In alternative embodiments, the spacer 175 may be a liquid lubricant (or grease) disposed between the bearing surfaces of the input shaft 160 and the chuck actuating shaft 164. Here, the liquid lubricant may be contained between the bearing surfaces of the input shaft 160 and the chuck actuating shaft 164 without any “third party” element being interposed between the bearing surfaces of the input shaft 160 and the chuck actuating shaft 164 (such as a solid body or a body having voids, as in the previous embodiments). By way of example only, seals may be provided to contain the liquid lubricant as desired.
Although the example embodiment may implement a polymer spacer 175, it will be appreciated that spacers 175 may be fabricated from numerous a varied alternative materials (other than polymers).
This US non-provisional application claims priority under 35 USC §119 to U.S. Provisional Application No. 60/724,987 filed Oct. 11, 2005, the content of which is incorporated herein in its entirety by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60724987 | Oct 2005 | US |
