Blind rivet nuts, fixing devices with blind rivet nuts, and fixing methods and processes
Blind rivet nuts are nuts that are designed to be securely connected by being installed on thin-walled carriers, especially on components made of metal plates, in order to provide them with fixing threads that can be used to secure bolts or screws. Blind rivet nuts can further be used to connect two or more thin-walled carriers or components to each other.
The rivet nut comprises a seating head intended to contact a first side of the carrier and a hollow shaft configured to be inserted into a through hole of the carrier. The hollow shaft includes a clamping portion designed to deform under axial tension to form a rib that moves against the second side of the carrier to clamp the carrier to ensure that the nut remains on the carrier. In addition, the nut is arranged in a blind hole type, that is, the nut is arranged in an area on the second side of the carrier without a passage to the second side. Typically, the shaft of a blind rivet nut includes a threaded portion for receiving a threaded element that enables the axial tensile force required to deform the clamping portion to be applied to the hollow shaft. This threaded portion is then used to screw into a screw or bolt intended to secure to a blind rivet nut. This blind rivet nut is known.
Screwing a threaded element into the threaded portion requires that the threaded element be accurately positioned and centered in a straight line on the threaded portion, so that the threaded element does not rest on the thread in an inclined manner and therefore become stuck during the screwing operation.
In this context, the object of the present invention is to provide a blind rivet nut, which has been improved in particular for use during mass production, and in which the screw or bolt intended to secure to the blind rivet nut is prevented from tilting and seizing during screwing in the blind rivet nut to the maximum extent possible. In addition, it is intended to elaborate fixing devices and fixing methods that have the same advantageous performance. This purpose is achieved by fixing blind rivet nuts with the characteristics of claim 5
According to the present invention, blind rivet nuts for blind riveting into openings in a carrier include, for example, thin-walled metal plates, annular flange shaped seating heads, and hollow shafts. The hollow shaft has a threaded portion for receiving threaded elements (such as screws or bolts) and a clamping portion adjacent to the seating head at its free end opposite the seating head. The clamping portion is designed to deform the blind rivet nut in a rib like manner during the operation of placing the blind rivet nut on the carrier, so as to thereby clamp the carrier between the rib like deformation portion of the clamping portion and the seating head. The invention further provides an additional unthreaded shaft portion formed in a hollow shaft between the clamping portion and the threaded portion. The unthreaded shaft portion is suitable for and configured to receive threaded self rolling or threaded self tapping screws or bolts in a rigid locking manner when the screws/bolts are screwed into the shaft portion.
The term thread self tapping is intended to be understood as introducing a thread into the unthreaded shaft portion of a blind rivet nut without cutting through a screw or bolt when screwing a screw or bolt into the unthreaded shaft portion, while the thread self tapping operation is intended to be understood as introducing a thread into the unthreaded shaft portion of a blind rivet nut through cutting through a screw or bolt when screwing a screw or bolt into the unthreaded shaft portion. When a screw or bolt has introduced a thread into the unthreaded shaft and the screw or bolt is screwed into the thread, rigid locking reception of the screw or bolt in the shaft is generated. A screw or bolt is used, for example, to secure another component to a blind rivet nut or carrier.
The specific advantage of blind rivet nuts is that when the set screw or set bolt is screwed into the unthreaded shaft, the set screw or set bolt neither tilts nor jams, because the set screw or set bolt itself forms a thread only when it is screwed into the unthreaded shaft. In addition, during screwing in operations, the unthreaded shaft advantageously causes the set screw or set bolt to automatically center in the unthreaded shaft of the blind rivet nut. The advantageous embodiment sets the unthreaded shaft portion to have a hole diameter that is smaller than the diameter of the clamping portion and larger than the diameter of the threaded portion. Thus, it is possible to ensure that during the operation of placing the blind rivet nut on the carrier, only the clamping portion with the largest hole diameter is plastically deformed, rather than the unthreaded shaft portion and the threaded portion.