CLAMPING DEVICE

Abstract

The clamping device comprises: a bolt member with a support head and a shank provided with a threaded portion, a locking clip (10) comprising a base (21) equipped with a through-hole (20) for the passage of the shank of the bolt member, and retaining means which are supported by the base (21) so as to be arranged vertically to the through-hole (20) and which are suitable for cooperating with the threaded portion to effect axial immobilization between the bolt member and the locking clip (10). The retaining means are constituted by flexible and elastic tongues (22, 23), arranged convergently. Their free ends (221, 231) define between them a gap (d) which is smaller than the nominal diameter of the threaded portion (15) so that they automatically enter into engagement with the threads of the threaded portion (15) when the shank (12) is inserted axially into the through-hole (20). A burr (29) directed toward the flexible tongues (22, 23) is provided at the periphery of the through-hole (20) to form a stop for the free ends (221, 231) when the shank (12) is axially withdrawn.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a U.S. National Phase Patent Application based on International Application Serial No. PCT/EP2007/002001 filed Mar. 8, 2007, the disclosure of which is hereby explicitly incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a clamping device.

2. Description of the Related Art

One known clamping device can be used in assembling a plurality of parts by axial compression, particularly by bolt and nut clamping. The parts are, for example, planar elements in the nature of plates, panels, metal sheets or the like. One class of element that has been known for many years is pincer-shaped nuts, that is, nuts having the general shape of a U and essentially comprising a first branch having a screw socket, connected to a second branch with an opening for the passage of a bolt. An example of this type of clamping device is described in the document FR2754575, with a nut forming a pincer further comprising an annular portion cut out of a flap bent back from the second branch so as to extend between the two branches of the nut and center it on one of the planar elements to be assembled.

The known clamping devices are not completely satisfactory, however, since the retaining means designed to cooperate with the threaded portion of the shank are in the form of screw sockets in which the threads of that portion can engage. To ensure clamping during assembly, it is therefore necessary to tighten the bolt member so that it is translated in a helical movement relative to the locking clip to effect the desired clamping. The mounting and manipulation time required for such assembly is long, especially when the dimensions of the parts to be assembled necessitate more than one clamping device. That time is directly related to the length of the threaded portion and to the relative arrangement of the parts. The significance of this drawback is all the greater since the clamping devices are used in final assembly lines, which are generally the most cost-intensive.

In addition, the pull-out strength of the bolt member is relatively low, since it is directly related to the mechanical strength of the screw sockets. The latter consist, for example, of rigid tongues punched and stamped from the base, whose free ends are rigidly engaged in the threads of the threaded portion. When a very high pull-out force is applied to the bolt member, the tongues will often deform (axially or radially) irreversibly and will unexpectedly release the bolt member.

SUMMARY OF THE INVENTION

The present invention provides a clamping device, including a bolt member with a support head and a shank provided with a threaded portion, a locking clip comprising a base equipped with a through-hole for the passage of the shank of the bolt member, and retaining means which are supported by the base so as to be arranged vertically to the through-hole and which are suitable for cooperating with the threaded portion to effect axial immobilization between the bolt member and the locking clip.

The present invention provides a clamping device that is of simple and inexpensive design, and which facilitates the assembly operation and increases the reliability of the assembly obtained.

This is achieved according to the invention by the fact that the retaining means are constituted by a plurality of flexible and elastic tongues, arranged convergently such that their free ends define between them a gap which is smaller than the nominal diameter of the threaded portion so that they automatically enter into engagement with the threads of the threaded portion when the shank is inserted axially into the through-hole, and by the fact that a burr directed toward the flexible tongues is provided at the periphery of the through-hole to form a stop for the free ends when the shank is axially withdrawn.

The axial insertion movement of the bolt member in the locking clip spreads the free ends of the flexible tongues apart radially. At the end of insertion, the elasticity of the flexible tongues automatically causes their free ends to engage with the threads of the threaded portion to the ensure retention and axial immobilization of the bolt member relative to the locking clip. To increase the clamping force produced by axial compression, the operator then need only tighten the bolt member slightly until a desired tightening torque is reached. In other words, assembly is effected, first, merely by exerting axial pressure on the bolt member relative to the locking clip, and then, optionally, by tightening the bolt member slightly. This feature facilitates assembly by virtue of the fast, simple manipulation of the bolt member.

When a pull-out force is applied to the bolt member, the free ends of the tongues come to rest against the respective ends of the burr. This deprives the free ends of the flexible tongues of their radial and axial mobility. The pull-out strength of the bolt member, which gives the clamping device its mechanical strength, is consequently very high, which helps to increase the reliability of the assembly.

In one form thereof, the present invention provides a clamping device including a bolt member with a support head and a shank provided with a threaded portion, a locking clip including a base equipped with a through-hole for the passage of the shank of the bolt member, and retaining means which are supported by the base so as to be arranged vertically to the through-hole and which are suitable for cooperating with the threaded portion to effect axial immobilization between the bolt member and the locking clip, a burr provided at the periphery of the through-hole, characterized in that the retaining means are formed by a plurality of flexible and elastic tongues, arranged convergently such that their free ends define between them a gap (d) which is smaller than the nominal diameter of the threaded portion so that they automatically enter into engagement with the threads of the threaded portion when the shank is inserted axially into the through-hole, and in that the burr is directed toward the flexible tongues to form a stop for the free ends when the shank is withdrawn axially.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of the locking clip in a first exemplary embodiment of the clamping device according to the invention;

FIG. 2 is a longitudinal sectional view of the locking clip from FIG. 1;

FIG. 3 is a perspective view of the first exemplary clamping device, showing a planar element to be assembled and the locking clip in cross section;

FIG. 4 is a perspective view of the locking clip in a second exemplary embodiment of the clamping device according to the invention;

FIG. 5 is a perspective view of the locking clip in a third exemplary embodiment of the clamping device according to the invention; and

FIG. 6 is a perspective view of the locking clip in a fourth exemplary embodiment of the clamping device according to the invention.

Corresponding reference characters indicate corresponding parts throughout the several views. Although the exemplifications set out herein illustrate embodiments of the invention, in several forms, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention to the precise forms disclosed.

DETAILED DESCRIPTION

FIGS. 1 to 3 illustrate a first exemplary clamping device according to the invention, composed of a locking clip 10 and a bolt member 11. The bolt member 11, which is made of metal, for example, and is visible only in FIG. 3, comprises a partially threaded shank 12 and, at the so-called proximal end, a support head 13. The shank 12 has a smooth upper portion 14 located close to the support head 13 and a threaded lower portion 15 extending to the opposite end, referred to as the distal end.

In the first embodiment, the locking clip 10 is configured as a straddle member having the general shape of a U, with substantially parallel first and second branches 16, 17. The locking clip 10 is fabricated by being cut from a metal plate and bent.

The clamping device will now be described in a specific but in no way limitative application example, consisting of the assembly of planar elements in the nature of plates, panels, metal sheets or the like. It goes without saying, however, that the clamping device can be used more generally in all applications requiring the use of a bolt and nut type system.

In this application example, one of the planar elements to be assembled, partially illustrated in FIG. 3 as reference 18, is designed to be placed between the branches 16, 17 of the locking clip 10. The other planar element or elements of the assembly are not shown. Branches 16, 17 can exhibit a slight convergence so that the locking clip 10 can be premounted and affixed to the planar element 18 prior to the final assembly operation executed in cooperation with bolt member 11.

First branch 16 and second branch 17 each have respective through-holes, referenced 19, 20, for the passage of the shank 12 of bolt member 11. First branch 16 terminates in an outwardly bent portion 24 designed to facilitate the placement of the locking clip 10 on the planar element 18.

According to the invention, second branch 17 constitutes a base, noted 21, supporting two flexible and elastic tongues 22, 23 disposed, relative to the base 21, on the opposite side from first branch 16. The flexible tongues 22, 23 are arranged to be convergent, such that their free ends, respectively referenced 221, 231, are situated vertically to the through-hole 20 and define between them a gap, noted d, which is smaller than the nominal diameter of the threaded portion 15. Each free end 221, 231 presents a circular hollow-out portion whose diameter corresponds to the inner diameter of the threading forming threaded portion 15. The opposite ends 222, 232 of the flexible tongues 22, 23 from the free ends 221, 231 are each integral to a respective connecting arm 25, 26 connected to the base 21 by a portion 27 bent back 1800, constituting an elastically deformable region. The connecting arms 25, 26 are perpendicular to their respective flexible tongues 22, 23. In the example described, flexible tongues 22, 23 and connecting arms 25, 26 are therefore coplanar, and are parallel to the base 21. Connecting arms 25, 26 are connected to each other by a stiffener 28, which is straight in the example.

When the operator assembles the planar elements using the above-described clamping device, the locking clip 10 is first premounted and attached to the planar element 18. The other planar element or elements that are to be assembled with element 18 are then superposed and are positioned against the first branch 16 or near it, outside the locking clip 10. Each planar element is provided with an opening designed to be traversed axially by the shank 12. The planar elements can each be integral to a respective part of any desired shape, said parts (not shown) being designed to be assembled to one another in a region where the planar elements are superposed and can be assembled by clamping.

The shank 12 of the bolt member 11 is then inserted into the openings in the planar elements to be assembled with element 18, proceeding from the distal end toward the proximal end, then into through-hole 19, then through planar element 18, then into through-hole 20, until coming into contact with the free ends 221, 231 of the flexible tongues 22, 23. The axial insertion of the shank 12 into the locking clip 10 then causes the flexible tongues 22, 23 to flex in such a way that their free ends 221, 231 move axially away from through-hole 20 of base 21. Due to the manner in which flexible tongues 22, 23 are supported on base 21, this flexing movement of the flexible tongues 22, 23 is accompanied by spreading of the free ends 221, 231 in the radial direction, commensurately increasing the gap d. These axial and radial movements of the free ends 221, 231, are facilitated and amplified by the presence of deformable regions constituted by bent portions 27. The stiffener 28 eliminates or at least limits the ability of connecting arms 25 and 26 to rotate about the axis perpendicular to the plane of the base 21.

At the end of the insertion of the bolt member 11, support head 13 butts against the relevant planar element, and the elasticity of the flexible tongues 22, 23 automatically causes their free ends 221, 231 to engage with the threads of threaded portion 15. More precisely, the hollowed-out portions come to bear linearly against the roots of the threads to effect the retention and axial immobilization of bolt member 11 relative to locking clip 10. The profiles of the flexible tongues 22, 23 at the opposite ends 222, 232 are chosen so that the free ends 221, 231 can be made to rotate by twisting the flexible tongues 22, 23, and thus to orient themselves to the angle of inclination of the threads of threaded portion 15. This feature increases the torque strength of the locking clip 10.

The axial immobilization serves to clamp planar element 18 together with the other planar element or elements, and thus to assemble them. To increase the clamping force produced by axial compression, the operator then need only tighten bolt member 11 slightly to a desired tightening torque. In other words, the assembly of the planar elements 18 and other elements is performed, first, merely by exerting axial pressure on the bolt member 11 relative to the locking clip 10, and then, optionally, by tightening the bolt member 11 slightly. This feature facilitates assembly by virtue of the fast, simple manipulation of the bolt member 11.

When a pull-out force is applied to the bolt member 11, the free ends 221, 231 of the flexible tongues 22, 23 come to rest against the top end of a burr 29 directed toward the flexible tongues 22, 23 and provided at the periphery of the through-hole 20. The burr 29 thus forms a stop for the free ends 221, 231 which deprives them of their radial and axial mobility. This effect is amplified by the presence of the stiffener 28. The pull-out strength of the bolt member 11, which gives the clamping device its mechanical strength, is consequently very high, which helps to increase the reliability of the assembly obtained.

The locking clip 10 and the bolt member 11 can be made from other suitable materials, varying with the application, such as molded plastic, for example. The number of flexible tongues 22, 23 can also vary with the application, based, for example, on the constituent material of the locking clip 10 and/or the desired rigidity during the axial insertion of the bolt member 11 and/or the sought pull-out strength.

FIGS. 4 and 5 respectively illustrate the locking clips 30 and 40 in two other exemplary embodiments of the clamping device according to the invention, usable in different applications. Locking clip 30 (FIG. 4) differs from locking clip 10 by the fact that first branch 16 has been eliminated. The manner of operation of the base 21 and the flexible tongues 22, 23 remains the same, however. Extending from one edge of the base 21 is a fixing flap 31 suitable for insertion in a mating receptacle provided in a first part to be clamped against a second part held in place by support head 13. The first and second parts are formed, for example, by the two articulated half-bores of a pipe clamp.

Locking clip 40 (FIG. 5) differs from locking clip 30 by the fact that the fixing flap 31 has been eliminated and the base 21 has larger dimensions in at least one of the directions, to be able to accommodate a plurality of fixing holes 41. The fixing holes 41 make it possible, for example, to overmold one of the parts to be clamped onto locking clip 40, or to affix the clip to one of the parts to be clamped by means of bolts or screws.

FIG. 6 illustrates the locking clip 50 in a fourth exemplary embodiment of the clamping device according to the invention. Locking clip 50 differs from locking clip 30 by the fact that the connecting arms 25, 26 extend beyond their junction with the opposite ends 222, 232 of the flexible tongues 22, 23. The free ends 251, 261 of the connecting arms, i.e., the opposite ends from those connected to the base 21, are connected to each other by a stiffener 51. The connecting arms 25, 26 and the stiffeners 28, 51 form a stiffening frame designed to eliminate any possibility of radial movement by free ends 221, 231 other than that caused by the flexion of flexible tongues 22, 23 during the insertion of bolt member 11. This feature increases both the pull-out strength of the bolt member 11 and the torque strength of the locking clip 50.

While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

1-9. (canceled)

10. A clamping device, comprising:

a bolt member including a support head and a shank provided with a threaded portion having a nominal diameter; and

a locking clip, comprising: a base including a through-hole; retainer structure supported by said base and disposed vertically with respect to said through-hole, said retainer structure cooperating with said threaded portion of said bolt member to effect axial immobilization between said bolt member and said locking clip, said retaining structure including a plurality of flexible and elastic tongues arranged convergently such that free ends of said tongues define therebetween a gap (d) smaller than said nominal diameter of said threaded portion, said free ends engaging threads of said threaded portion upon insertion of said shank into said through-hole; and a burr disposed at a periphery of said through-hole, said burr directed toward said tongues and forming a stop for said free ends when said shank is withdrawn.

11. The device of claim 10, wherein second ends of said flexible tongues opposite from said free ends are each integral to a respective connecting arm, each connecting arm connected to said base by an elastically deformable region.

12. The device of claim 11, wherein said connecting arms are interconnected by at least one stiffener disposed parallel to said base.

13. The device of claim 10, wherein said free ends of said flexible tongues include hollowed-out portions.

14. The device of claim 10, wherein said base includes a branch, and wherein a device to be clamped is receivable between said base and said branch.

15. The device of claim 14, wherein said locking clip is substantially U-shaped, with said branch substantially parallel to said base, said branch disposed on an opposite side of said base from said flexible tongues.

16. The device of claim 14, wherein said base includes a plurality of fixing holes.

17. The device of claim 14, wherein a fixing flap extends from an edge of said base.