Device for keeping plastic fastening elements at the ready

Plastic parts are held by a holding device in a position for transfer to a receiver. Each part has a wall with a pierceable wall region that is accessible from one side, and the holding device is provided with a needle. With the part in the transfer position, the pierceable wall region is pressed against the needle, so that the needle penetrates the pierceable wall region and the wall is secured to the needle. The holding device may be a magazine type with multiple sockets for holding corresponding parts on needles.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of German Patent Application No. 10 2006 048475.4 filed Oct. 11, 2006, incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to a method and apparatus for holding parts such as plastic elements in a position for transfer to a receiver, such as a tool that uses the parts. The invention also relates to parts constructed for use in such method and apparatus.

Plastic fastening elements are frequently used in vehicles to attach cables, conduits, paneling elements, or the like to parts of the vehicle. In this connection, it is frequently desirable for the fastening elements to be installed in an automated fashion, for example with the aid of a robot. For automated installation, it is necessary to place a fastening element at the ready in a definite transfer position in which it can be grasped by the installation tool of the robot so that it can then be installed in the required fashion. In other cases, it can also be necessary to keep the fastening element at the ready in an assembly or installation tool, so that by actuating the tool, the assembly or installation can be executed. Plastic fastening elements are embodied in a wide variety of forms, so that keeping the various fastening elements at the ready is often difficult and requires a variety of holding devices. In addition, it is sometimes a challenge to design the fastening elements so that they can be held and secured by the available holding devices.

BRIEF DESCRIPTION OF THE INVENTION

An object of the invention is to provide a method and an apparatus for holding parts such as plastic fastening elements at the ready, more particularly for holding uniquely constructed parts at a transfer position, where the parts can be delivered to a receiver, such as a tool.

Parts utilized in the invention have a wall with one or more pierceable wall regions, and a holding device for the parts has one or more needles. With a part in a predetermined position, a pierceable wall region is pressed against a needle, so that the needle penetrates the pierceable wall region, and the wall is secured to the needle.

In an embodiment of the invention, a holding device is in the form of a magazine with multiple sockets provided with needles, each socket holding a corresponding part. A slider pushes a part situated in front of the slider off the needles of the socket, so that the part is transferred to a receiver.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a section of a wall1of a plastic fastening element in one embodiment of the invention. In the vicinity of its edge, the wall1is provided with a recess2that forms a wall region3with a significantly thinner wall thickness. The thickness of the wall region3is dimensioned so that the wall region3can be pierced by a sharp needle4without exerting a large amount of force. The needle4is part of a holding device that serves to keep the fastening element at the ready for transfer to a receiver, such as a tool for automatic installation or assembly of the fastening element. At its free end, the needle4has a tip5and, spaced apart from the tip, has a holding recess in the form of an annular groove6, or a notch or undercut.

In the embodiment, the recess2is round and has a diameter D. Alternatively to this, however, the recess can also be embodied in an oval or polygonal form. The needle has a diameter d, which is considerably smaller than the diameter D of the recess. This diameter difference means that the center of the recess can have an offset x in relation to the central axis of the needle4, which corresponds to half of the difference of the diameters D minus d, without hindering the insertion of the needle4into the wall region3and without causing constraining forces to act on the needle in a transverse direction. The embodiment of the wall region3in relation to the needle4consequently permits a fastening of the wall1through insertion of the needle4into the wall region3, even when the fastening element with the wall1is not exactly aligned in relation to the needle4, but when the needle4is inserted in a region that is offset from the needle4by an amount determined by the diameters D, d. Thus, manufacturing tolerances are accommodated.

In order to secure the wall1, it is pressed with its pierceable wall region3against the sharp end of the needle4. The needle4penetrates the wall region3and elastically and plastically deforms it while forming a hole. In the position of the wall1achieved by a stop7of the holding device adjacent to the needle4, the edge of the opening, which is pierced by the needle4and encompasses the needle4in an elastic fashion, engages in the material of the annular groove6, fixing the wall1on the needle4in a fashion suitable for temporarily holding it.

A single needle can sometimes be sufficient to hold a part if the part is small and additional supports can be provided on the holding device. In many cases, however, it is suitable to fix a part with several needles at several points.FIG. 2shows one such example. A plate-shaped holding device10is provided with three needles11spaced uniformly apart from one another, only two of which are visible in the drawing. The needles hold a fastening element12, which is designed to be fastened in a circular opening in sheet metal. The fastening element12has an annular flange13, which has thin-walled, pierceable wall regions14spaced the same distance apart as the needles11. Oriented so that the wall regions14are situated in front of the needles11, the fastening element12is pressed against the holding device10. As a result, the needles11pierce the wall regions14as shown, forming openings whose edges adhere to the outside surface of the needles11in a frictionally engaging fashion (with or without needle recesses). The contact of the fastening element12against the holding device10defines the final position in the axial direction of the needles11. The fastening element12is thus placed in readiness in a position in relation to the holding device, which position is defined in all three spatial directions in relation to the holding device, so that a subsequent assembly procedure can start from this position.

FIG. 3shows a round magazine20, which is composed of a rotatable disk21and an annular holding device22situated on the rim of the disk21. The holding device22is coaxial to the rotation axis of the round magazine20and on its outside has a multitude of sockets23spaced uniformly circumferentially. Each socket23is provided with several parallel needles24that project outward, each set of which holds a respective fastening element25in the above-described manner. In the center of each socket, the annular holding device22is provided with a through bore26. On the inside of the holding device22is situated an actuator27, which is equipped with a radially mobile slider28that is aligned with a through bore in the depicted position of the round magazine20and, when the actuator27is triggered, can move outward through the through bore26. The socket23′ in front of the slider28is situated at a position provided for transferring a fastening element25to a receiver such as an assembly tool. If such a tool is situated on the outside, in front of the socket23′, ready for transfer of the fastening element25, then the actuator27is triggered and the slider28pushes the fastening element25off of the needles and toward the assembly tool. This simplifies the transfer, so that the assembly tool does not have to be brought snugly against the round magazine20.

After the fastening element is transferred, a stepper motor (not shown) rotates the round magazine20by a fraction predetermined by the spacing of the through bores so that the slider can transfer the next fastening element.

FIG. 4shows a section through a pierceable wall region31composed of a film30on a wall32of a fastening element. The film covers an opening33in the wall32and, after the manufacture of the fastening element, can be welded to the wall or stuck to the wall in the form of a self-adhesive film.

If it is not possible to manufacture the pierceable wall region with a thin enough film, then it is possible, as shown inFIG. 5, for the pierceable wall region35to be perforated with a hole36. The diameter of this hole36, however, must be smaller than the diameter of the needle.

FIG. 6shows a variant in which the pierceable wall region38of a wall39is provided with a slit40. The width of the slit40, too, must be smaller than the diameter of the needle.

The above-described method, and the apparatus described for executing it are suitable not only for plastic fastening elements, but also for a wide variety of parts that must be kept in readiness for processing steps or between such processing steps. The invention is particularly advantageous when the outer form of the parts does not provide any suitable engagement surfaces for holding mechanisms.

While preferred embodiments of the invention have been shown and described, it will be apparent that changes can be made without departing from the principles and spirit of the invention, the scope of which is defined in the accompanying claims. For example, a multi-socket magazine may be rod-shaped, rather than round, with needles of adjacent sockets projecting in the same direction from one side of the magazine, and with the slider arranged at the opposite side of the magazine and adjustable along the length of the magazine to different positions at which the slider can eject corresponding parts from the magazine.