Fastening device and system for pre-assembling a pin-shaped connecting element

Abstract

Fastening means for pre-assembling a pin-shaped connecting means in a through-opening (1) of a component (2), wherein the fastening means comprises a sleeve (3) and a plurality of inwardly projecting holding elements (4) on the inner side (5) of the sleeve (3), wherein a recess (7) formed in an outer wall of the sleeve (3) is provided for the locking engagement of a projection (8) located in the through-opening (1) during pre-assembly, and wherein the sleeve (3) is cylindrical in shape and the recess (7) is formed in the outer wall in the circumferential direction, characterized in that concave indentations of the outer wall form the inwardly projecting holding elements (4), wherein corresponding outdentations (9) remain in the outer wall of the sleeve (3), wherein the indentations and the outdentations (9) extend over the entire height of the sleeve (3), and wherein a chamfer (12) is formed at each of the two ends of the sleeve (3).

Description

The invention relates to a fastening means for pre-mounting a pin-shaped connecting element, in particular a screw, in a through-opening provided in a component. For holding the connecting element, the fastening means has a sleeve, which is in particular cylindrical shell-shaped, and a plurality of inwardly projecting holding elements on the inner side of the sleeve. The invention also relates to a system consisting of such a fastening means and a component produced by injection molding or die casting with a through bore.U.S. Pat. No. 5,395,194 A discloses a fastening means designed as a sleeve which has sections which are alternately curved outwards and inwards in the circumferential direction. In this case, the outwardly curved sections hold the fastening means in the bore in a force-fitting manner, while the inwardly facing sections hold an inserted screw in a force-fitting manner. In order that the sleeve does not slide too deeply into the through bore, a step is provided in the bore, on which step the front end face of the sleeve in the insertion direction is supported. The requirement of the step makes the production of the bore complicated.DE 10 2009 016 633 A1 discloses a similar fastening means which, in addition to the inwardly projecting holding elements which hold the pre-assembled connecting element, additionally has further holding elements projecting outwards at both ends of the sleeve. These are elastically deformable, so that they can initially execute an outward movement when the fastening means is inserted into the through bore. In addition, these outwardly protruding holding elements, which engage behind the edges of the through bore, prevent an axial displacement of the fastening means inserted in the through bore during pre-assembly and during the later final assembly of the connecting element. In order to enable the outward protruding holding elements to be gripped from behind, the through-bores in the components must be machined in an additional working step.DE 11 2012 001 820 T5 discloses a fastening means for pre-mounting a pin-shaped connecting means in a through-opening of a component, wherein the fastening means has a sleeve, a plurality of inwardly projecting holding elements on the inside of the sleeve and a recess introduced in an outer wall of the sleeve.The object of the invention is now to propose a fastening means which is simple and cost-effective to produce and by means of which the pre-assembled connecting element is held securely in the through bore of the component. In addition, the object is to create a system comprising such a fastening means and a component provided with a through bore and in the process being simple to produce.These objects are achieved by the fastening means according to claim 1 and the system according to claim 8, wherein the dependent claims each describe advantageous embodiments.The basic idea of the invention is to introduce a recess into the outer wall of the fastening means designed as a sleeve in such a way that a shoulder located in the through-opening or remaining during production latches into it during pre-assembly. With the shoulder snapped into the recess in this way, the fastening means according to the invention with the connecting means inserted therein, in particular with the inserted screw, is secured against axially slipping out of the through bore. In order to enable this function, the recess must be designed accordingly such that it has a stop on each side in the axial direction. The recess is therefore advantageously formed as a slot in the outer wall of the sleeve running perpendicular to the axis of the sleeve.The particular feature of the fastening means according to the invention is that it does not require the outward-protruding latching lugs known from the prior art. This reduces the risk of chip formation when the fastening means is pressed into the through bore.An important aspect of the invention is that with this design of the fastening means it becomes possible to produce the through-bores in components in a particularly simple manner and thereby to dispense with subsequent machining. Finally, components with pre-assembled connecting means that are produced in a printing or injection molding process are suitable as components. In this case, through-holes are regularly formed by means of two core trains which are pulled apart during demolding. Usually, after demolding, an annular shoulder remains, which in the prior art has to be removed by a post-processing step, for example by drilling or punching. According to the invention, however, this remaining annular shoulder is not removed but rather used to provide a hold for the fastening means. In principle, it is sufficient to use the paragraph which sometimes inevitably remains during production. However, it is advantageous, with regard to the fastening means according to the invention, to design the core trains such that a defined, in particular annular, shoulder remains in the through bore.The invention is thus manifested in the use of this remaining shoulder and thus in a system having a fastening means with a recess according to the invention and having a component produced in a casting process with at least one through bore which is formed by two core lines which leave an annular shoulder in the through bore during demolding.In general, the sleeve according to the invention can have an outer wall of any desired configuration. This can be angular or corrugated, for example. In a particular embodiment, the sleeve is cylinder jacket-shaped, wherein the recess is introduced into the outer wall of the cylinder jacket in the circumferential direction. The cylinder jacket does not have to have a circular cross section.In a particularly preferred embodiment, the fastening means has the basic shape described in U.S. Pat. No. 5,395,194 A with sections which are alternately curved inward in the circumferential direction ("indentations") and sections which are curved outward ("bulges"), wherein the surfaces of the bulges lie on an imaginary circle. The concave indentations of the outer wall form the inwardly projecting holding elements. With respect to the imaginary circle, the bulges remain to some extent in the outer wall of the sleeve. In order to ensure the simplest possible production and good retention of the connecting means in the fastening means and of the fastening means in the through bore, it is advantageous if the indentations and the bulges run over the entire height of the sleeve.The surfaces which are formed by the concave indentations of the outer wall are suitable for applying an informative inscription, for example the material, a nest mark and / or a date. The advantage is that these surfaces do not come into contact with the bore wall and therefore the risk of chip formation is reduced.In a particularly preferred embodiment, the recess is formed by a slot running with respect to the imaginary circle, which slot traverses the bulges on a corresponding circumference, omitting the bulges. This slot is advantageously not only formed on the surface of the outer wall, but penetrates the material thereof, and is thus continuous. Because of these "partial" slots in the jacket surface of the sleeve, the fastening means latches in the corresponding bore. As a result, it is introduced in the bore in a captive manner.In order to simplify the subsequent feeding and the preassembly, it is particularly advantageous to design the fastening means symmetrically with respect to the slot running over the circumference. For this purpose, the slot runs at the middle height and optically divides the sleeve into two identical parts. By positioning the slot centrally, the fastener will insert at least 1⁄4 of the way into the bore before the snap-in function begins. As a result, the fastening means is guided securely, so that tilting during the application of the clip-in force is avoided.Depending on the insert, the fastening means or the sleeve is preferably either integrally injection-molded or die-cast from a plastic; the sleeve can also be manufactured from a metal. In this way, the fastening means can be produced in large numbers at low cost, wherein the particular shape of the fastening means enables production without subsequent processing.In order to increase the flexibility of the sleeve and thus to further simplify the clipping into the through bore, it can be advantageous to slit the wall of the sleeve from one end to the other end, so that the diameter can be somewhat reduced under pressure from the outside. Ideally, such a slot has an axial orientation and is introduced in the region of a concavity. In this case, the slot is advantageously produced already during the casting of the sleeve and is not introduced subsequently.The particular advantages of the fastening means or of the sleeve formed according to the invention are also that an inserted connecting means, in particular a screw, can be moved axially in the sleeve with a defined force without the sleeve being pulled or pressed out of the bore. In addition, the screw can be locked in any desired position. A special feature of the geometry according to the invention is also that the sleeve can be pressed into the bore individually with a defined force even without a screw. This special geometry increases the positive fit of the fastening means in the component.A further advantage is that the fastening means can be pre-mounted on the shank region of the screw and the pre-mounted "screw-sleeve connection" can be pressed into the bore in one operation.Further features and advantages result from the following description with reference to the figures. The following are shown: FIG. 1 shows a fastening means in a perspective view, and FIG. 2 shows a fastening means in a through bore of a component.FIG. 1 shows a fastening means for pre-mounting a pin-shaped connecting means, not shown, in particular a screw, in a through-opening 1 of a component 2 shown cut open in FIG. 2, The fastening means is a cylindrical sleeve 3 injection-molded in one piece from plastic, which has four inwardly projecting holding elements 4 in the form of bulges on the inner wall 5. The screw is inserted in a known manner into the bore of the sleeve 3 and held in a force-fitting manner by the holding elements 4.According to the invention, the sleeve 3 has in its outer wall 6 a recess 7 for the latching engagement of an annular shoulder 8 (FIG. 2 ) located in the through-opening 1. The locking takes place when the sleeve is inserted into the through bore 1 during the preassembly. In the exemplary embodiment shown, the sleeve 3 has a cylinder jacket-shaped contour. The recess 7 is accordingly introduced into the outer wall 6 of the sleeve 3 in the circumferential direction (arrow A).As can be seen, the concave indentations of the outer wall 6 form the inwardly projecting retaining elements 4, wherein correspondingly four indentations 9 remain in the outer wall 6, the outer surfaces of which engage the inner wall 10 of the through bore 1. In order to ensure stable retention of the sleeve 3 in the through bore 1 and reliable fixing of the screw in the sleeve 3, the indentations and the bulges 9 run over the entire height of the sleeve 3.As can be seen from the figures, the structures of the sleeve 3, namely the indentations and the bulges 9, have a rotational symmetry at a 90° pitch. The recess 7 is formed by a slot in the material of the four bulges 9 which runs around an imaginary circumference of the sleeve 3, wherein the slot pierces the bulges 9 and is therefore continuous. However, the slot is not so deep that it affects the material of the indentations. In addition, the slot runs at the middle height and optically divides the sleeve 3 into two equal parts.The surfaces which are produced by the concave indentations on the outer wall are provided with a characterizing inscription 11-here "HONSEL" and "HPF".In order to ensure simple and reliable insertion of the sleeve 3 into the through bore, a chamfer 12 is formed in each case on both ends of the sleeve 3. The through bore also has a chamfer 13.FIG. 2 shows the system comprising the fastening means embodied as a sleeve 3 and the component 2 having a through bore 1, wherein the component 2 is produced in a casting process. During the production of the component 2, the through bore 1 is formed by means of two core lines which leave behind an annular shoulder 8 in the through bore 1 during demolding. The geometry and the position of the annular shoulder 8 is determined by the abutment surfaces and the arrangement of the core trains and can be defined accordingly. In the present case, the annular shoulder 8 is located in the middle of the through bore 1. The annular shoulder 8 formed in this way latches into the recess 7 located in the outer wall of the sleeve when the sleeve 3 is inserted into the through bore 1.

Claims

Fastening means for pre-mounting a pin-shaped connecting means in a through-opening (1) of a component (2), wherein the fastening means has a sleeve (3) and a plurality of inwardly projecting retaining elements (4) on the inner side (5) of the sleeve (3), wherein a recess (7) introduced in an outer wall of the sleeve (3) is provided for the latching engagement of a shoulder (8) located in the through-opening (1) during pre-mounting, and wherein the sleeve (3) is introduced in the shape of a cylinder jacket and the recess (7) is introduced in the circumferential direction into the outer wall, characterized in that concave indentations of the outer wall form the inwardly projecting retaining elements (4), wherein corresponding bulges (9) remain in the outer wall of the sleeve (3), wherein the indentations and the bulges (9) extend over the entire height of the sleeve (3) and wherein a chamfer (12) is formed at each of the two ends of the sleeve (3).Fastening means according to Claim 1, characterized in that the recess (7) is formed by an in particular continuous slot which passes through the bulges (9) on an imaginary circumference, leaving out the bulges.Fastening means according to claim 2, characterised in that the slot runs at the middle height and optically divides the sleeve into two identical parts.Fastening means according to one of the preceding claims, characterized in that the indentations and the bulges (9) are arranged symmetrically around the circumference of the sleeve (3).Fastening means according to one of the preceding claims, characterized in that the sleeve (3) is injection-moulded in one piece from plastic.Fastening means according to one of the preceding claims, characterized in that the wall of the sleeve (3) is interrupted from one end to the other end by a slot which runs in the axial direction.Use of an annular shoulder (8) in the through bore (1) of a component (2) for holding a fastening means according to one of the preceding claims, wherein the component (2) is produced by an injection molding or die casting process and the annular shoulder (8) has remained in the through bore (1) during the demolding of two core lines and wherein the annular shoulder (8) engages in a recess (7) which is located in the outer wall of a sleeve (3) formed by the fastening means.System consisting of a fastening means according to one of the preceding claims 1 to 6 and a component (2) with a through bore (1), wherein the component (2) is produced in an injection or casting process, characterized in that the through bore (1) is formed by two core lines which leave behind an annular shoulder (8) in the through bore (1) during demolding, wherein the annular shoulder (8) engages into the recess (7) located in the outer wall of the sleeve (3).System according to claim 8, characterised in that the annular shoulder (8) is located in the middle of the through bore (1).System according to claim 8 or 9, characterised in that a chamfer (13) is formed on the edge of the through bore (1).

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