FR2504616A1 - BUILT-IN TAPPING ELEMENT - Google Patents

Abstract

THE SUBJECT OF THE INVENTION IS A RECESSED ELEMENT INTENDED TO BE INSERTED IN A HOLE IN THE FORM OF ADVANCE AND INCLUDING A TUBULAR BODY 10 THREADED INTERNALLY WITH A WIDERED HEAD 12 AT ITS REAR END AND A SERIES OF FINS 16, 17, 18 BETWEEN HEAD 12 AND ITS FRONT END. HEAD 12 IS SHAPED WITH TEETH PROFILES TO WITHSTAND TORQUE STRAIN WHEN THE ELEMENT IS IN PLACE. THE DIAMETERS OF FINS 16, 17, 18 INCREASE FROM THE FRONT END TO THE REAR END OF THE ELEMENT TO BE RECESSED.

Description

25046 1

  The invention relates to a built-in element intended to be inserted into a hole formed in advance in a part to establish a threaded anchor point The invention particularly conceives a built-in element which is intended to be put in place as a press fitting and fitted with profiles to resist axial extraction and

solicitation of a couple.

  The object of the present invention is to propose a tapped element to be built-in of the stated type which is of economical manufacture and which, in particular when it is inserted in parts made of thermoplastic material, does not subject

  not the material of the part to excessive stresses.

  According to the present invention, a recessed element intended for its insertion into a hole formed in advance in a room is established so as to constitute a threaded anchoring point, said element comprising a presel body

  both at its rear end an enlarged head provided with

  wires to resist a couple and between the head and its front end a plurality of peripheral fins spaced from each other and from said head, each of these fins comprising a front flank which, in the radial direction towards the outside, is inclined away from the front end of the element and a rear flank which extends practically perpendicular to the main axis of the element to be embedded or is inclined in the same direction

  that the front flank, the diameters of said fins increase

  both in a direction away from the front end

of the element to be built in.

  This configuration is particularly suitable for inserting the element by force fitting into a

  plastic material because the front flanks of the fins facilitate

  attempt to push in the insertion of the element to be built in while the rear flanks offer considerable resistance to extraction stresses due to the tendency of the plastic to return to its original form and thus occupy the region located immediately behind the rear flank of each fin In addition, the configuration of a fin allows the fin to undergo a certain elastic bending at its end, thus facilitating insertion and increasing the resistance to extraction (particularly in hard materials that cannot

return to their primitive form).

  When the element to be built-in is inserted in the

  by force by a press-in operation, the successive fins tend to tear off part of the wall of the insertion hole. Such tearing can make the following fins less effective in resisting

  to an extraction To remedy this, as mentioned above

  above, the diameters of the successive fins progressively increase from the front end to the rear end so that each subsequent fin tends to become embedded

  further into the wall of the room hole.

  The angle of inclination of the front flank with said main axis is preferably between 45 e and 60 ′. An angle of this order associated with the arrangement of intervals between the head and the neighboring fins avoids applying excessive stress to the part. and consequently the risk of rejection of parts after production of fractures during the operation

installation.

  To facilitate automatic feeding, for example

  ple from a feed bowl, and to correct

  the% orientation of the element to be embedded, this element is advan-

  markedly formed with a diametrical slot through its front end, this slot having dimensions and an arrangement such that the body of the element does not have in this region a notable tendency to flatten radially (because of the presence of the slit) when it is introduced into a thermoplastic material as opposed to known forms of split elements in which the slit is established to allow such a radial flattening to be carried out thereby helping the introduction into hard materials Of such known built-in elements are not inserted by force fitting but their radial flattening ability allows their insertion into a hole. The following introduction of a threaded fixing member into the element then serves to expand the element in forcing the peripheral profiles of

  this element to be embedded in the material.

  To foster a more complete understanding of

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  the invention, an example of its execution will now be described.

  tion with reference to the accompanying drawing, the single figure of which is a side view of a built-in element according to the invention. As shown, the element to be embedded comprises a tubular body 10 of generally cylindrical shape having an internal thread. At its rear end, the body 10 has a radially enlarged head 12 which is provided with axial teeth opposing a resistance to the stress of a torque when the element is installed in the room which receives it At its front edge, there is a pilot part 14 which can be of the same diameter as the body of the element which in turn is of a slightly smaller diameter that the diameter of the hole in which it must be embedded The pilot part 14 is used to place the element in the mouth of the hole

before pushing it there by pressure.

  On its periphery, the body of the built-in element: is formed with one or more fins 16, 17 and 18 whose outer diameters gradually increase so that the front fin 16 is of the smallest diameter while the rear fin 18 is of the largest diameter The diameter of the fin 18 immediately adjacent to the part forming the head 12 can be the same as the head diameter or be slightly smaller Each fin has an inclined front flank 20 and a rear flank 21 which extends little

  near perpendicular to the axis of the element to be embedded.

  A diametrical slot 22 extends through the end

  mite before but, as mentioned above, this slot is intended to assist the feeding and orientation of the element to be embedded and it is of an arrangement

  dimensions such that the element to be embedded has not

  noticeable tendency to flatten radially when inserted

  press fitting in a thermoplastic material.

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Claims (6)

R E V E N D I C A T I O N S.   1 Built-in element intended to be introduced into a hole formed in advance in a part so as to constitute a threaded anchoring point therein, said element comprising a body (10) having at its rear end, an enlarged head (12 ) fitted with profiles to resist torque and, between   head and its front end, a plurality of fins peri-   sphericals separated from each other and from said head, each of these fins comprising a front flank which, in a direction oriented radially outwards, is inclined away from the head end of the element to   recessed and a rear flank which extends almost perpetually   specifically to the main axis of the element to be embedded or   is inclined in the same direction as the front flank, the diameters   very of said fins increasing in a direction which   moves away from the front end of the element to be built in.   2 built-in element according to claim 1, wherein the angle of inclination of the front flank is between 450 and   600 with respect to said main axis.   3 recessed element according to claim 1 or claim 2 which is formed with a diametrical slot   through its front end, this slot having dimensions   sions and an arrangement such that the body of the element does not have a notable tendency in this region to flatten radially (due to the presence of the slot) when   introduced into a thermoplastic material.   4 Built-in element according to any one of   previous claims, in which the head is formed with axial teeth.   5 recessed element according to claim 4, wherein the outer diameter of said teeth is more   larger than the diameter of the nearest fin.   6 built-in element according to claim 3, comprising a pilot part, said slot being formed in the pilot part without interrupting the nearest fin.   from the front end of the element to be built in.