Weld stud

[0002] The present invention relates to a weld stud which is welded to a workpiece and attaches a component to the workpiece, and an attachment assembly using the weld stud. More specifically, the present invention relates to a weld stud which is effective in being utilized, but not limited, as a synthetic resin weld stud to be welded to a box member made of synthetic resin such as a dashboard or some other structural part of an automobile, or a cowling of a motorcyle.

[0003] Conventionally, in a clip assembly commonly used for attaching a component on a box member made of synthetic resin such as a dashboard of an automobile or a cowling of a motorcycle, as shown in FIG. 1, the root of a weld stud 1 having an engagement step 1aat a longitudinally mid portion is welded to a box panel 2, and a clip 3 comprises a tubular leg portion 3awith an inner diameter enough to receive the stud 1 and a disc-like head 3bformed on an upper end of the leg portion. The clip 3 is brought into engagement with the stud 1, thereby holding another component 4 sandwiched between the head 3band the box-like panel 2. To make the clip 3 engage with the stud 1, resilient engagement pawls 3 are provided in the manner that they extend inwardly with respect to the tubular leg portion 3aof the clip 3c, and the engagement pawls 3care brought into engagement with the engagement step 1aof the stud 1.

[0004] For this conventional attachment assembly, different clips have to be prepared correspondingly to components to be attached. Further, forming the engagement pawls in the clip needs complicated metal molds, which should be made for the respective types of clips, resulting in an increase in manufacturing costs. Difficulty in removing the clip after attached is another problem of this type of conventional attachment assemblies.

[0005] Noting such problems in the conventional component attachment assemblies, the present invention aims to provide an attachment assembly which can be used in common with various components to be attached without being changed depending on the various components and be removed easily after mounted and, further, to provide a weld stud for use with the above attachment assembly.

[0006] In order to attain the above object, a weld stud according to the present invention comprises a leg portion having a first end and a second end spaced from the first end, a flat mounting seat adapted to be welded to a workpiece and integrally formed with the leg portion, and a resilient engagement pawl portion integrally formed on at least one side of the leg portion. The resilient engagement pawl portion extends diagonally outwardly from the first end of the leg portion toward the second end to be capable of bending radially inwardly with respect to the leg portion, and an engagement step which is an inward recess formed on an intermediate outside portion of the resilient engagement powl portion. Although a weld stud according to the present invention is not necessarily made of synthetic resin, it is preferred that the weld stud is made of synthetic resin and is molded as a one-piece article since its use is predominantly for synthetic resin members.

[0007] In a preferred embodiment of the present invention, the leg portion is formed to have substantially flat surfaces on both sides thereof and engagement pawl portions in a pair are formed respectively along the substantially flat surfaces on both sides of the leg portion.

[0008] According to the present invention, there also is provided an attachment assembly comprising a weld stud of any of the above-described types and a clip including an engagement portion to engage with the weld stud. In this case, the clip is formed with a hole having a radius as sized so as to allow the engagement pawl portion or portions of the weld stud to bend and pass therethrough. The clip is provided with a substantially flat engagement surface defining an engagement portion on the upper peripheral surface of the hole.

[0009] In the attachment assembly using the weld stud of the present invention, it is not essential to use a clip to engage with the stud. In a case of using no clip, a component to be attached may be formed with an attachment portion having an engagement portion or an engagement surface to engage with the stud. In those attachment assemblies, less kinds of weld studs than the clips can be used and the same type of the clip can be used in different places, so that manufacturing costs can be reduced by providing engagement means in the stud itself Even in another case of using a clip, only a hole should be formed in the clip, so that the manufacture cost of the clip can be reduced. Besides, according to the structure of the engagement pawl portion of the stud of the present invention, after the weld stud is attached, the engagement pawl portion can be bent from outside to allow the component to be removed.

[0010] FIG. 1 is a sectional view showing an example of a component attachment assembly of a conventional structure.

[0011] FIG. 2(a) and FIG. 2(b) show a front view and a side view, respectively, of an embodiment of a weld stud of the present invention.

[0012] FIG. 3 is a sectional view showing an example in which the stud of FIG. 2(a) is used without a mounting clip.

[0013] FIG. 4 is a sectional view showing an example in which a component is attached by means of the stud of FIG. 2(a) using a mounting clip.

[0014] The present invention is described further by way of an embodiment, with reference to accompanying drawings, FIG. 2(a) and (b) are a front view and a side view, respectively of a weld stud 10 of an embodiment according to the present invention. The stud 10 has an appropriate flat mounting seat 11 which is, for example, a circle in the form, and a mounting leg portion 12 which extend upwardly from the mounting seat 11 and has flat sides 12a. Along the flat sides 12aof the mounting leg portion 12, a pair of resilient engagement pawl portions 13 are formed so as to extend diagonally outwardly from a first end 12bof the leg portion 12, formed with the seat 11, and toward a second end 12cof the leg portion. In an intermediate outside portion of each of the resilient engagement pawl portions 13 between the first end 12band the second end 12c, an engagement step 13ais formed as an inward recess.

[0015] Preferably, the weld stud is made of synthetic resin and is formed as a one-piece article. For example, as shown in FIG. 3, the stud 10 is welded at its mounting seat 11 to a workpiece panel such as a box panel 14 made of synthetic resin. In FIG. 3, an attachment component 15 is mounted directly on the box panel 14, without using any mounting clip. In this example, the attachment component 15 is formed with a first hole 15ato be penetrated by the stud 10. On the inner wall of the hole 15a, an inwardly projecting engagement portion 15bis formed. The engagement portion 15bis formed with a second hole 15cwhich is concentric with the hole 15a, but having a smaller diameter. The smaller diameter of the hole 15cis sized to allow 16chaving a radius sized to allow the engagement portions 13 to bend and pass therethrough, and the top surface of the engagement portion 15bdefines an engagement surface. The attachment component 15 is fixed onto the box panel 14 when the engagement steps 13aof the engagement pawl portions 13 of the stud 10 come into engagement with the engagement surface on the top of the engagement portion 15bof the attachment component 15.

[0016] FIG. 4 shows an example of using the embodiment weld stud 10 of the present invention for mounting a clip 16 for an electric wire. The clip 16 has a holder portion 16ato hold a wire 17 or the like and a mounting portion 16bformed integrally at an end portion of the holder portion 16a. The mounting portion 16bmay be a simple, disc-like member. It suffices that the mounting portion 16bis formed with, for example, a round hole 16chaving a radius sized to allow the engagement pawl portions 13 of the stud 10 to bend and pass through. In this case, the top surface of the mounting portion 16bdefines an engagement surface. Since the mounting portion 16bof the clip 16 can be in a simple annular form, manufacturing costs will be reduced remarkably.

[0017] In the above embodiment, the engagement pawl portions 13 of the stud 10 are formed on both sides of the leg portion 12. Nevertheless, the engagement pawl portion formed only on one of the side can satisfactorily fulfil the intended function. It is also possible that the weld stud is made of metal such as iron-based metal.