Spring arm sleeve

A spring arm sleeve with which a joining element of a joining device is positionable and which comprises the following features:

• a. an entry end, an exit end and a tubular section which is formed by a circumferential wall, wherein the tubular section defines a first longitudinal direction,
• b. the circumferential wall comprises in a circumferential direction a plurality of U-shaped apertures regularly spaced from one another,
• c. wherein the plurality of apertures forms a plurality of one-sidedly fastened spring arms which are inclined radially inwards into the tubular section, in which
• d. in the first longitudinal direction of the tubular section,
• d1. at a first length at least three spring arms are arranged in the circumferential direction evenly spaced from one another and
• d2. at at least one second length different from the first length at least three spring arms are arranged in the circumferential direction evenly spaced from one another, wherein
• e. the first and the second length are measured between the entry end of the spring arm sleeve and a center of the respective spring arms and
• f. each spring arm extends toward the exit end starting from a respective fixed end in the first longitudinal direction;
• wherein the at least three spring arms of the second length are arranged at circumferential positions which are located between the at least three spring arms of the first length, and
• the first length and the second length as well as a length of the spring arms are selected in such a manner that the spring arms of the first length and the spring arms of the second length overlap each other in the longitudinal direction of the tubular section.