Metal working – Means to assemble or disassemble – Puller or pusher means – contained force multiplying operator
Reexamination Certificate
2001-04-18
2002-08-06
Hail, III, Joseph J. (Department: 3723)
Metal working
Means to assemble or disassemble
Puller or pusher means, contained force multiplying operator
C029S280000, C029S282000
Reexamination Certificate
active
06427304
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for removing dowel formlockingly anchored in a bore and including an anchor rod having a head portion widening toward a free end of the anchor rod, and a sleeve having radially expandable expansion tabs at its one end and having a load application element at its other opposite end. Here, “formlockingly”, a term used in the art, indicates a positive engagement of elements of the dowel in complementary shaped recesses or grooves formed in the bore in which the dowel is anchored.
2. Description of the Prior Act
For a heavy load anchoring, in particular, for achieving a reliable attachment, often, formlockingly anchorable dowel systems are used. A main element of such dowel system is an undercut self-cutting dowel which is anchored in a bore, while forming an undercut during the setting or anchoring process. Also, dowels can be used which engage an undercut preliminary formed in the bore in which the dowel is to be anchored. A conventional dowel has, as a rule, an anchor rod with a head portion which widens toward the free end of the anchor rod. A sleeve having an expansion region is axially displaceable along the anchor rod. The expansion region of the sleeve is formed of a plurality of expansion tabs separated from each other by longitudinal slots. The expansion tabs expand upon displacement of the sleeve over the conical head of the anchor rod. In the undercut self-cutting dowels, cutting bodies are provided on the outer surfaces of the expansion tabs and which, upon rotation of the sleeve during the sleeve displacement over the conical head, form an undercut in the bore wall. Such an undercut self-cutting dowel is disclosed, e.g., in U.S. Pat. No. 4,702,654.
In constructional works, it is often necessary, after a removal of an attached constructional part, to completely removed the formlockingly anchored dowel. With existing undercut self-cutting dowels, this is, as a rule, not possible or, even if possible, is associated with substantial expenses. Often, only the anchor rod is separated at the bore mouth, and the bore is closed. The dowel, which remained in the bore, can present problems during a subsequent attachment of another constructional element. Because of the difficulties associated with the removal of the dowels, the inspection of the attachment points is also associated with substantial difficulties. When undercut self-cutting anchors are used, it can happen that an anchoring process cannot be completed because the expansion tabs encount a reinforcing metal. In this case, a partially anchored dowel need be removed. As it has already been discussed above, this is associated with substantial expenses, and often satisfactory results cannot be obtained.
Accordingly, an object of the present invention is to provide a device for completely removing a partially or completely anchored dowel.
Another object of the present invention is to provide a dowel-removing device having a robust structure and which is easy to use
SUMMARY OF THE INVENTION
These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a dowel-removing device including a sleeve-shaped support member having, at its one end a support shoulder, an indexing projection extending beyond the support shoulder and provided with a load application element movable in a tensile operational engagement with the load application element of the dowel sleeve. A through-bore extends through the support sleeve including the indexing projection and is provided, at least regionwise, with an inner thread. A shaft is received in the through-bore. The shaft has an outer thread which cooperates with the inner thread of the through-bore to provide for a relative axial displacement of the shaft with respect tot he support member upon notation of the shaft. The shaft has, at its opposite longitudinal ends, identical coupling elements. The device further includes an adaptor including an elongate sector having at its free end a connection element corresponding to the coupling element of the shaft and a diameter smaller than an inner diameter of the through-bore of the support sleeve. The adaptor has, at its ends opposite the elongate section, a shank receivable in a chuck of a hand-held tool.
The inventive dowel-removing device insures a complete, simple, and reliable removal of a partially or completely anchored undercut-engaging dowel which can be formed either as a conventional dowel engaging a preliminary formed undercut or as an undercut self-cuffing dowel which forms an undercut upon being anchored. The shaft, which cooperates with the inner thread provided in the support member bore, is easily adjusted with respect to the support member. The adaptor serves for transmitting of a rotational movement from a hand-held tool to the shaft. The adaptor can be coupled alternatively to one or another end of the shaft. For removal of the dowel, the indexing projection is so connected with the rear end of the dowel sleeve that it remains unaffected by the tensile forces.
The support member is supported, in the region of the bore mouth, either against a constructional part or against a constructional component. During the withdrawal of the dowel, the adaptor is connected with the shaft end remote from the indexing projection. Upon rotation of the shaft about its longitudinal axis, it displaces relative to the support member, until it abuts the end surface of the dowel anchor rod. Upon further rotation of the shaft, a pulling force is applied to the dowel sleeve, whereby the sleeve is pulled out from the bore. After lifting of the dowel-removing device, the anchor rod can be withdrawn from the bore. Thereafter, the adaptor is connected with the another end of the shaft, with the shaft being returned to its initial position upon its rotation. It is advantageous, from the manufacturing point of view when the coupling elements, which are provided at the opposite longitudinal ends of the shaft, are formed as pegs having a non-circular cross-section. Then the connection element, which is provided at the free end of the adaptor, is formed as a blind bore having a cross-section corresponding to the cross-section of the peg. A particularly simple and tested geometry of the connection is provided when both the pegs and the blind bore have a hexagonal cross-section.
According to a preferred embodiment of the present invention, the adaptor is provided with an annual band which separates the elongate section of the adaptor from a section provided with the shank. The outer diameter of the band is larger than the inner diameter of the through-bore formed in the support member. The band prevents, upon withdrawal of the shaft, any contact between the drill chuck and the load application element provided on the indexing projection. This prevent any damage of the chuck and/or the load application element. Rather, as soon as the band contacts the indexing projection, automatic decoupling of the shaft from the adaptor takes place. The length of the elongate section, which includes the connection element cooperating with the shaft coupling element, is so selected that it corresponds to that of the support member, insuring return of the shaft to a position optimal for removing a dowel. Thereby, preliminary adjustment of the dowel-removing device for a subsequent removal is eliminated. Advantageously, the length of the elongate section from the band to its free end is selected within a range from about 20 mm to about 200 mm, preferably, from 30 mm to 130 mm.
According to a particularly advantageous embodiment of the present invention, the load application element provided on the indexing projection includes radially projecting pins which formlockingly engage correspondingly formed undercut recesses at the rear end of the dowel sleeve. The selected geometry of the load application element on the indexing projection is robust, is easily formed, and makes the load application element easily engageable with the correspon
Kaibach Werner
Negele Hans-Jürgen
Raber Stefan
Hilti Aktiengesellschaft
Sidley Austin Brown & Wood LLP
Wilson Lee
LandOfFree
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