Patent Application
20100111639
Galling is a condition that can occur when two pieces of the same metal are rubbed together. Galling can be a problem if the two surfaces are intended to move relative to each other in use. Friction between the surfaces results in localized material transfer between the surfaces. Generally galling occurs when the two surfaces experience relative motion while subject to a sufficient compressive stress to permit the transfer of material. The stress between the surfaces tends to disrupt any protective oxide layer that is naturally present and allow metal-to-metal contact. Pure metal-to-metal contact without an oxide or other separating layer will facilitate a cold welding process thereby joining the surfaces together and preventing further relative motion therebetween.
Galling often occurs between an expander portion and an expansion sleeve of an anchor bolt when installing the anchor bolt into a base material. Depending upon the severity of the galling, the expander sleeve may be pulled from the base material rather than expanded properly by the expander portion of the bolt, thereby defeating the anchor. Additionally, galling increases the force required for removal of the anchor during intended disassembly. The art will be receptive to alternative configurations minimizing or eliminating galling.
According to one aspect of the invention, an anchor bolt includes a wedge having a surface with a plurality of protrusions and a sleeve in operable communication with the surface, the sleeve expandably receptive to the surface.
According to another aspect of the invention, a method to reduce galling of an anchor bolt includes reducing contact area between a wedge surface and a sleeve of the anchor bolt.
According to yet another aspect of the invention, a method to reduce a breaking force between galled components of an anchor bolt includes, reducing contact area between a wedge surface and a sleeve of the anchor bolt.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
Referring to
The surface 29 of the wedge 20 has a generally tapered shape that may be conical for wedges 20 having a round cross section. Further, an angle 40 of the taper of the surface 29 may remain constant over a longitudinal length of the surface 29 as illustrated herein. Alternately, the angle 40 may be variable over the longitudinal length. Embodiments herein are not limited to being conical in shape, however, and may be any other shape that is effective in acting as a wedge.
The surface 29 as shown includes a plurality of recessions 31 that correspond with the plurality of protrusions 30. The plurality of protrusions 30 may have a knurled pattern. In the example depicted in
As detailed above, the wedge 20 is in operable communication with the sleeve 14 during setting of the anchor bolt 10. In the embodiment shown in the Figures, the sleeve 14 is a fully bored formed cylindrical sleeve having an inner diameter 34 that is greater than the outer diameter 35 of a shank 36 of the anchor bolt 10. In this embodiment, the sleeve 14 is free to rotate around the shank 36 before setting. The sleeve 14 is also shown having the at least one gripping projection 37. The at least one gripping projection 37 helps to grip the base material 22 and increase friction between the sleeve 14 and the hole 24 during setting of the anchor bolt 10. The at least one gripping projection 37 is shown oriented in a latitudinal direction but may also be a longitudinal projection or may have a non-axial shape. Additionally, sleeve 14 is shown having at least one longitudinal slot 38 on the body of the sleeve 14. The at least one longitudinal slot 38 allows the sleeve 14 to be radially deflected without the necessity of stretching the material of the sleeve 14 itself In other embodiments, the sleeve 14 may be configured for being stretched.
It should be understood that the invention is not limited to the configurations depicted in the Figures. The anchor bolt 10 may be any anchor having a metallic wedge that expands a metallic portion of the anchor during setting. Furthermore, the stud 12 and the sleeve 14 may be fabricated of any metal susceptible to galling, such as, stainless steel, low carbon steel, cast iron, copper, aluminum, magnesium, and titanium, for example.
While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims.
