Centering sleeve and fastening method

1. A sleeve for the centering of fasteners when installing structural parts on substructure of a building envelope, the sleeve comprising:

a hollow cylindrical sleeve body or split hollow cylindrical sleeve body having at least two gutter-shaped shell elements, each having:

a head end and a rear end,

the at least two gutter-shaped shell elements are grouped symmetrically about a central axis A, and

inner surfaces facing each other in a middle space spanning between them; and

the shell elements are spaced apart from each other and separated by axially parallel longitudinal slots except for a connecting joint section at the head end;

wherein the middle space spanned by the inner surfaces of the gutter-shaped shell elements has a funnel shape with a diameter widening toward the rear end.

2. The sleeve as claimed in claim 1 , wherein the inner space in the area of the joint section or near the head end has a narrowing in formed as an internally circular tube section with a diameter d.

3. The sleeve as claimed in claim 2 , wherein the narrowing is adjoined by a funnel-shaped widening toward the head end.

4. The sleeve as claimed in claim 2 , further comprising, in or near an area of the narrowing, a clamping element comprised of a membrane, a partially pierced membrane, or finger-shaped holding elements.

5. The sleeve as claimed in claim 1 , wherein the joint section comprises a material bridge with a predetermined breaking point.

6. The sleeve as claimed in claim 5 , wherein the predetermined breaking point comprises a notch, a narrowing, or a constriction.

7. The sleeve as claimed in claim 1 , wherein the inner surfaces of the gutter-shaped shell elements have a stepped stairway or ribbed surface.

8. The sleeve as claimed in claim 1 , wherein one said longitudinal slot has a wedge shape, as viewed from an outside, and widens from the head end to the rear end.

9. The sleeve as claimed in claim 1 , wherein the sleeve body comprises, at a front end, a set-back stop surface or multiple surfaces forming a stop surface.

10. The sleeve as claimed in claim 1 , wherein the sleeve is a one-piece injection molded or compression molded element.

11. The sleeve as claimed in claim 1 , wherein the sleeve comprises a plastic, a biodegradable plastic, bonded paper fibers, plant fibers, or a composite material.

12. A method for fastening a facade element on a substructure of a building envelope, the method comprising the following steps:

a) providing a fastener having a head with a purchase point, a threaded shaft, and a tip, with a sleeve placed on the tip of the fastener, the sleeve including a hollow cylindrical sleeve body or split hollow cylindrical sleeve body having at least two gutter-shaped shell elements, each having a head end and a rear end, the at least two gutter-shaped shell elements being grouped symmetrically about a central axis A, and inner surfaces facing each other in a middle space spanning between them, the shell elements are spaced apart from each other and separated by axially parallel longitudinal slots except for a connecting joint section at the head end, and the middle space spanned by the inner surfaces of the gutter-shaped shell elements has a funnel shape with a diameter widening toward the rear end;

b) inserting the fastener in a predrilled hole of said facade element, such that flange-shaped stop surfaces of the sleeve lie against a surface of the facade element;

c) pressing the sleeve against the predrilled hole, so that the inner surfaces come at least partially into contact with the thread on the shaft of the fastener;

d) driving the fastener forward;

e) sinking the fastener into the predrilled hole until the tip of the fastener reaches the substructure, the sleeve accomplishing a centering of the fastener in the predrilled hole of the facade element;

f) spontaneous ejecting of the shell elements from the predrilled hole of the facade element by driving home the fastener, once the centering has been assured;

g) completion of the fastening, leaving behind no remainder of the sleeve in a resulting fastener—facade element—substructure assemblage.