FR2484566A1 - PRESSURE PLASTIC FIXING DEVICE - Google Patents

Abstract

THE INVENTION RELATES TO A PRESSURE-LAYING PLASTIC FIXING ORGAN. THIS ORGAN INCLUDES A ROD 14 SOME OF WHICH AXIAL SURFACES 16 HAVE FLEXIBLE FINS 30 INCLINED TOWARDS THE HEAD 12. THE JUNCTION OF THESE FINS 30 WITH THE SURFACES 16 IS REALIZED SO THAT THE FORCE REQUIRED FOR LAYING THE ORGAN 10 IS VERY LOWER THAN THAT NECESSARY TO REMOVE THIS ORGAN 10 FROM THE HOLE IN WHICH IT WAS INTRODUCED. FIELD OF APPLICATION: FIXING OF AUTOMOTIVE DOOR TRIMS, ETC.

Description

Press-fitting plastic fasteners having

various configurations, are

  described in particular in the United States patent of

  Nos. 3,810,279. Such fasteners, although suitable for many applications, raise a particular problem of their own, that is, the force required to place the fastener in a hole or in a bore of a part is substantially equal to the force required to remove the fastener of this hole or bore. In some applications, it has been found desirable to use a fastener which can be easily laid, but which requires a very large

force to be removed.

  The invention provides an improvement to the

  fixing device described in US Pat. No. 3,810,279.

  cited, and it relates more particularly to a fastener comprising a single piece consisting of a head and a rod, the latter having a cross section

  substantially non-circular which has several

  approximately planar faces, extending axially. Each of the planar surfaces of the rod carries a plurality of resilient, flexible and axially spaced fins, which fins may flex along their straight lines of connection with the planar surfaces. Some fins on at least one of said surfaces are inclined to bend toward the head and have means substantially increasing the force required to remove the fastener from a hole or bore relative to to the force necessary for the introduction of the organ

fixing in the hole.

  The invention relates to a fastener of the type generally described above, comprising inclined fins which are articulated, each fin

  having, on its upper surface, a portion of

  strongly arranged at a certain angle and causing a

  bending of the blade roughly parallel to the over-

  plane face, but at a point radially distant from it. The fastener according to the invention is inexpensive and can be easily molded into a two-plate mold. It can have many different head shapes, as well as several configurations of the nose or

  of the different entry part.

  The invention will be described in more detail with reference to the accompanying drawings by way of non-limiting example and in which: - Figure 1 is an elevation of an embodiment of the fastener according to the invention; - Figure 2 is a partial axial section along the line 2-2 of Figure 1; FIG. 3 is an end view, partly in section, taken on line 3-3 of FIG. 2, showing the inlet end; FIG. 4 is a partial axial section,

  on an enlarged scale, improved fins of the

  fixing device according to the invention; FIG. 5 is an elevational view of a press-fit fastener according to the prior art; FIG. 6 is a partial elevation of a press-fit fastener comprising

  inclined fins which do not have the perfection-

  of the invention; - Figure 7 is a partial elevation of the fastener according to the invention;

  FIG. 8A is a diagrammatic view of

letters of the prior art;

  FIG. 8B is a diagrammatic view of

  letters corresponding to an intermediate development, of the type shown in FIG. 6; and FIG. 8C is a diagram of blades of

  the fixing member according to the invention.

  A fastener made of plastic material,

  by pressure, of the advanced type to which the invention

  tion is generally designated by the appropriate reference

  10 and comprises a head 12 and a rod 14. Although the head 12 of the fastener according to the invention is shown as a head with a curved upper surface, it is obvious to those skilled in the art that this form is only one example of a head profile. The fixing member according to the invention may comprise a single

  head 12, as shown, or several heads spaced

  axially, of the type normally used for fastening

  trim panels inside car doors

mobileS (not shown).

  The importance of the invention lies in the fact that the press-fitting plastic fastener can be easily mounted in a drilled panel or in a bore of a thick panel, so that

  the force required to remove the organ be much higher than

  greater than the laying force. An embodiment of such a fastener is shown in Figures 1 to 4, 7 and 8C. The rod 14 of this fastener is of substantially non-circular or polygonal shape and has several flat and axial surfaces 16 which, in the embodiment described, are four in number. It is obvious, however, that even

  flat surfaces may be suitable. Several fins

  the axially spaced tongues and hoses 18 project outwardly from the flat surfaces 16 and have a substantially inclined lower surface 20 and a

  radially oriented upper surface 22, as shown in FIG.

in figure 2.

  A plurality of resilient fins 30, disposed along at least one planar surface 16, are inclined upwardly with respect to the axis of the rod 14, as shown in the drawing, towards the head 12. The improvement initially provided to this fastener was to use an inclined fin, as shown in Figure 6, having substantially the same configuration as the flexible fins 18 which protrude radially outwardly. As shown in FIG. 6, these fins, indicated generally at 32, flex along a straight line formed at their junction with the plane surface 16. The insertion forces

  and removal of such organs are slightly different.

  annuities. Another improvement has led to the embodiment shown in FIGS. 1 to 4 and 7, in which each inclined fin 30 receives a

  articulated portion 34, so that the fins 30 pre-

  feel a flexion line 36, as shown in the figure

  7, which is substantially parallel to the surface 16,

  but spaced radially outward from this last

  In this embodiment, a substantially short, truncated fin 30 can be readily inserted into a hole or bore, but with a large force against removal of the hole or bore fastener. The tests have been carried out on various fin configurations and the results of these tests indicate, in newtons, the force required to push the fastener into position and pull it off. Values

  The figures relate to the configurations of

  8A, 8B and 8C, the latter

  presenting the embodiment of the invention. The test results are as follows: Figure 8A Input Output

107 142

93 102

89,102

98

107 93

98 93

98 103

98 89

93 85

89 80

, 7 98.8

Figure 8B Input Output

44.5 to 82.3

51.2 64.5

49 73.4

46.7 57.8

46.7 66.7

44.5 64.5

46.7 55.6

44.5 55.6

44.5 53.4

44.5 53.4

MEDIUM

46.3 62.7

Figure 8C Input Output

133.5 333.7

, 7,333.7

89,311.5

111.2 356

111.2 367.1

, 7,289.2

111.2389.4

89,333.7

, 1,333.7

122.4 322.6

, 9,337.3

RETRIEVAL / INSERTION REPORTS

1.4 3.2

  1.0 As indicated, the fastener according to

  the invention, shown in FIG. 8C, makes it possible to obtain

  excellent and unforeseen results.

  It is stated herein that the elastic fins 30, of improved shape and having articulation portions 34, project in opposite directions from two flat surfaces 16 of the rod 14, whereas the radial fins 18 are

  located on the other two flat and opposite surfaces.

  It should be noted that the withdrawal force can be determined, in the case of a fixing member of this design, according to the number of surfaces carrying inclined and articulated fins 30. It is sufficient that the

  fins 30 protrude from one or more of the

  faces. However, all surfaces can carry such fins. In the case where the fins 30 or 18 project only one or two surfaces (this case not being shown), it has been found desirable to provide a means such as an axial centering rib (not shown). , to place the fastener under optimal conditions of use with respect to

  hole or the complementary bore.

  Although the rod 14 shown has four flat surfaces 16, it is obvious that the fins 18 and 30 may project and extend over the entire width of the flat surface or that, alternatively, the rod 14 may have, if that is desired, several recesses 40 extending axially and intersecting and spacing adjacent flat surfaces to receive a tool

axially elongated.

  Nose 44 of the described embodiment

  is represented as having the shape of an arrow. He.

  It should be noted, however, that other configurations may also be used. The end of the rod 14 may be blunt, rounded, arrow-shaped or

tapered, as desired.

Claims (9)

  1. A one-piece fastener made of plastic material, pressure-laid, characterized in that it comprises at least one head (12) and a rod (14) which comprises an axial body, substantially polygonal, having a plurality of substantially planar surfaces (16) facing radially outwardly, a plurality of independent and resilient fins (18) made   in one piece with the body and protruding radially   outside each of the surfaces, to   axially spaced intervals, the joining of   lines and surfaces along a straight line that con-   titue a bending line of said fins during the introduction of the fastener in a room   complementary breakthrough, some fins (30) being   paced along at least one of said surfaces from which they protrude and being inclined towards the head, and means, made in one piece with each of these fins, substantially increasing the force required to remove the fixing of the hole in relation to the force necessary to introduce this organ of fixing in the hole.   2. fastener according to claim 1, characterized in that the means associated with certain   fins comprise an articulated portion (34) which   terminates a bending line (36) substantially parallel to one of said body surfaces, said bending line being at a certain radial distance   and outside said surface.   3. Fixing member according to claim 2, characterized in that the articulated part comprises   a substantially thickened zone at the junction of   say some fins and said surface.   4. Fixing member according to claim 3, characterized in that the thickened zone is located on the upper surface of said fins facing towards the head to form a non-uniform surface of which   radially spaced points form different angles   with the body, the junction of these points forming   said flexure lines radially spaced.   5. Fastening member according to claim 4, characterized in that the body has a section   four-sided and in that   tilted and inclined are located along two opposite flat faces.   6. fastener according to claim 4, characterized in that it comprises two heads held at a distance from one another, close to from one end of the stem.   7. fastener according to claim 4, characterized in that it comprises three heads held at a distance from each other, close to from one end of the stem.   8. Fixing member according to claim 4, characterized in that said surfaces are separated from each other by recesses (40) arranged angularly.   Fastening member according to claim 1, characterized in that the fins on at least one surface are axially offset fins on the other surfaces to establish various hold lengths.