Fastening clip

A fastening clip structured to attach a plate-shaped structural part with a second plate-shaped part is disclosed. The parts have fastening openings, one of the openings being oblong. The clip includes a head having a radial conical flange adapted to engage the respective structural part, and a shank having a plurality of resilient legs, the legs being connected to the head at the upper end thereof and forming a conical insertion tip at the free end thereof. The outer sides of the legs have a shoulder adapted to cooperate with the edge of the hole, wherein four legs are provided circumferentially spaced by 90.degree., the legs being separated by relatively broad slots extending from flange to the insertion tip, the maximum diameter of the shank at the level of the shoulders being slightly larger than the shortest diameter of the oblong hole.

TECHNICAL FIELD
 The invention relates to a fastening clip for connecting two plate-shaped
 structural parts.
 BACKGROUND ART
 Such fastening clips are known in the most varied of design embodiment
 forms and generally include a head that comprises a conical flange which
 more or less sealingly bears against the facing side of the structural
 part and is axially deformable in a limited manner in order to ensure a
 height compensation. On the head of the fastening clip there is formed a
 shank which consists of two or more legs which may be radially sprung and
 which at the free end run out into an introduction end and in each case
 comprise a shoulder radially on the outside, with which a hole edge is
 gripped from behind.
 Such fastening clips are normally injection moulded as one piece from
 plastic material. Their attachment often requires a considerable
 application force which however is mostly smaller than the holding force.
 It is the object of the invention to provide a fastening clip for
 connecting two plate-shaped structural parts comprising fastening holes,
 which by way of a slight finger pressure may be mounted in the fastening
 hole, which at the same time ensures a relatively high holding force and
 which furthermore may be unloseably preassembled in a structural part with
 an oblong fastening hole. Furthermore the fastening clip is manufactured
 with minimal expense.
 SUMMARY OF THE INVENTORY
 With the fastening clip according to the invention there are spaced four
 legs arranged in the circumferential direction by about 90.degree., which
 are separated by relatively wide slots extending from the flange to the
 introduction end. The individual legs comprise on the outer side a
 shoulder with a maximum diameter which is somewhat larger than the
 smallest diameter of the oblong hole. Preferably, the shoulders are
 circular in cross section as also the legs below the shoulders in cross
 section have a circular contour so that a type of basket is formed which
 in relation to the leg sections above the shoulders in the direction of
 the head is relatively stable, by which means a high holding force is
 created. The thin leg sections above the shoulders permit a simple spring
 deflection of the legs on introducing into the fastening hole so that the
 pressing in force is conceivable small. If the introduction or assembly
 force is for example maximumly 60N, then accordingly the holding force
 after locking into the fastening hole is at least 250 N.
 For the series manufacture of such a fastening clip it is advantageous when
 the head comprises an axial oblong opening which is aligned with two
 diametrically arranged slots in the shank, wherein the ends of the opening
 lie on an axis to the shaft axis which extend through neighbouring
 circumferential ends of neighbouring shoulders. In this manner a core may
 be introduced over the oblong hole into the shank region of the fastening
 clip which at the same time forms two diametrical slots between the legs.
 The two other diametrically oppositely lying slots are then created with
 the help of the sliders of the injection moulding mould.
 According to another formation of the invention above the flange there is
 formed a cup-shaped portion which on the upper side is deepened in a
 concave manner. In this manner the assembly of the fastening clip may be
 simplified by finger pressure.

BEST MODE FOR CARRYING OUT THE INVENTION
 The fastening clip shown in FIGS. 1 and 2 comprises a head 10 and a shank
 12. The head 10 has a cone-like radial circular flange 14 which bears
 against the facing outer side of a plate-shaped structural part 16. The
 head 10 further comprises above the flange 14 a cup-shaped portion 18
 which is formed ball-cap shaped and on the upper side comprises a concave
 recess 20. The concave recess provides for the improved use of a detent
 force of the fastening clip with finger pressure.
 The shank 10 extends through fastening holes of the plate-shaped structural
 part 16 as well as the plate-shaped structural part 22. At 24 the
 fastening hole of the structural part 16 and at 26 the fastening hole of
 the structural part 22 are indicated. The first hole is oblong, as is
 deduced from the common observation of FIGS. 1 and 2. The second hole is
 circular.
 The shank 12 comprises four legs 28 arranged at a circumferential distance
 of 90.degree.. The legs 28 are separated from one another by relatively
 wide, straight, axially parallel slots 30. The legs 28 are connected to
 the head 10, and specifically via a relatively thin leg section 32 which
 in cross section is approximately triangular, but with a circular outer
 contour (FIG. 4). The leg sections 32 extend up to the shoulders 34 which
 in the circumferential direction has a circular contour and lies on a
 circle whose diameter is larger than the smallest diameter of the oblong
 hole 24. By way of this the shank 12 may be preassembled in the oblong
 hole without there arising the danger that the fastening clip releases.
 Below the shoulders 34 there are provided leg sections 36 which form a
 conical introduction end that tapers downwards to a rounded introduction
 tip 38. In cross section the leg sections 36 are likewise also circular.
 By way of this a type of basket is formed which is relatively stable in
 comparison to the leg sections 32. On introduction of the fastening clip
 into a fastening hole the shoulders 34 yield slightly so that only a
 relatively slight finger pressure is sufficient to assemble the fastening
 clip. The relatively large shoulders and the more stable leg sections 36
 however ensure a high withdrawal force.
 The shaping of the fastening clip according to the FIGS. 1 to 4 is effected
 in an injection moulding mould, wherein the core can be guided via an
 oblong opening 40 whose extension in the longitudinal direction reaches
 until up to the shoulders 34. Diametrically oppositely lying slots, as can
 be seen in FIG. 2 are therefore moulded with the help of the core (not
 shown), whilst the other two diametrical slots 30 which only extend to the
 lower edge of the flange 14 are formed by slider parts which are a
 component of the injection moulding mould.