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CN-224229068-U - Reverse rivet nut and forming device thereof

CN224229068UCN 224229068 UCN224229068 UCN 224229068UCN-224229068-U

Abstract

The utility model discloses a reverse rivet nut and a forming device thereof. The reverse rivet nut comprises a flange, a step and a conical rod part which are sequentially arranged along an axis, and is provided with threaded holes penetrating through all parts, wherein the step is arranged on the end face of the flange in a protruding mode around the threaded holes, a plurality of tendons surrounding the step are arranged on the end face of the flange, the conical rod part is arranged on one side, away from the flange, of the step, and the outer wall of the conical rod part is inclined towards the axis direction to form a groove structure. The forming device comprises a cold header and a matched die assembly thereof, wherein the die sequentially performs multi-station plastic processing on the nut to sequentially finish forming of the straight section of the rod part, the flange step, the chamfer angle, the tendon, the groove and the through hole. The structure and the device can realize the efficient one-step forming of the reverse rivet nut, not only improves the pulling resistance and the torque holding capacity of the nut, but also reduces the material waste and the processing error, remarkably enhances the controllability of the product quality and the automatic integration capacity of the technological process, and has good practicability and popularization value.

Inventors

  • PAN JUNJUN
  • QIAN QIUFANG
  • LIU YUBAO
  • WANG TAN

Assignees

  • 欧拜欧(昆山)汽车紧固件有限公司

Dates

Publication Date
20260512
Application Date
20250627

Claims (7)

  1. 1. A reverse rivet nut is characterized by comprising a flange, a step and a conical rod part which are sequentially arranged along an axis, and a threaded hole penetrating through the flange, the step and the rod part along the axis is formed, the step is arranged on the end face of the flange in a protruding mode around the threaded hole, the outer round radius of the step is smaller than the outer round radius of the flange, a plurality of tendons are arranged on the end face of the flange around the step, the conical rod part is arranged on the end face of the step in a protruding mode around the threaded hole, the radius of the conical rod part gradually increases along with the distance from the step, and a groove is formed between the outer wall of the conical rod part and the end face of the step and is inclined towards the center of the axis along the outer wall of the conical rod part.
  2. 2. The reverse rivet nut as defined in claim 1, characterized in that said flange and steps are in the shape of regular hexagons, said tendons being evenly distributed around the steps for connecting edges of said steps.
  3. 3. The reverse rivet nut of claim 1, wherein the end face of the tapered shank portion is further provided with a smooth bevel for enhancing the pull-out force.
  4. 4. A forming device for manufacturing the reverse rivet nut according to any one of claims 1 to 3, comprising a cold header and a die assembly mounted on the cold header, wherein the die assembly comprises: A first die for shaping a blank to form the blank into a straight section for shaping a stem; The second die is used for shaping the blank formed by the first die to preform the flange and the step; The third die is used for shaping the blank formed by the second die to form a flange end chamfer; The fourth die is used for shaping the blank formed by the third die to form tendons, rod parts and screw holes; a fifth die for shaping the blank formed by the fourth die to form a groove between the rod part and the step; And the sixth die is used for processing the blank molded by the fifth die so as to remove the waste materials in the screw holes.
  5. 5. The molding apparatus of claim 4, wherein the first mold, the second mold, the third mold, the fourth mold, the fifth mold, and the sixth mold each comprise a main mold and a die disposed corresponding to the main mold; The main die comprises a main die shell, a main die cushion block, a main die thimble and a main die core, wherein the main die cushion block, the main die thimble and the main die core are arranged in the main die shell, the main die core is provided with a main die cavity with an opening facing the die, the main die thimble penetrates into the main die cavity from the bottom of the main die core, the die comprises a die punching shell, the die cushion block and the die thimble are arranged in the die punching shell, one end of the die thimble is connected with the die cushion block, and the other end of the die thimble penetrates out of the die punching shell and is opposite to the main die cavity.
  6. 6. The forming apparatus of claim 4, further comprising a shearing mechanism for shearing the wire into the nut blank.
  7. 7. The molding apparatus of claim 4, further comprising a feed mechanism for feeding between the plurality of molds.

Description

Reverse rivet nut and forming device thereof Technical Field The utility model belongs to the technical field of fasteners, and particularly relates to a reverse rivet nut and a forming device thereof. Background The fastening connection technology has an irreplaceable position in sheet structures such as automobile bodies, rail transit, household appliance sheet metal, energy storage shells and the like. Along with the acceleration of the light weight of the whole machine and the trend of process integration, the blind rivet nut capable of completing assembly on one side is widely adopted because double-sided operation is not needed, and hole expansion and thread embedding can be simultaneously realized. However, in the conventional forward rivet nut, a pulling force is required to be applied from one side of the surface in the installation process, and the turning deformation direction is the same as the operation end. When the assembly space is limited, the outer appearance surface is not allowed to be damaged, or the plate can only obtain clamping force from the back surface, the traditional structure often cannot meet the application requirements of reverse stress and front riveting, so that the assembly process is limited or an auxiliary clamp is required to be additionally designed, and the manufacturing cost and the field operation difficulty are obviously increased. On the other hand, to reduce the cost of a single piece and improve the utilization of materials in mass production, fastener manufacturing has generally employed cold heading instead of multiple machining routes. However, the shape of the blind rivet nut gradually tends to complex geometric characteristics such as a multi-step flange, tendons, anti-slip teeth, a thin-wall conical rod part and the like, the conventional two-to-four-station cold header is difficult to finish fine forming at one time, and enterprises have to adopt a compromise scheme of cold header blank and secondary machining. The method not only weakens the advantage of near net forming of cold heading, but also increases the energy consumption and manufacturing cost of unit parts due to the increase of cutting scraps and cutter loss. Meanwhile, based on hardening characteristics of difficult-to-process materials such as high-strength steel, stainless steel or aluminum magnesium alloy, the problems of local stress concentration, service life attenuation, quality fluctuation of internal threads of a workpiece and the like of the die are increasingly outstanding, and the consistency and the production takt of products are restricted. The existing special rivet pulling gun and nut system also face the dilemma that the installation load curve is greatly influenced by the hand force of an operator, the air pressure fluctuation and the hardness discreteness of a base material, so that the riveting quality is not easy to control, meanwhile, the torque transmission and the pulling resistance between the nut and a base material are required to be compatible with high strength and long service life, and loosening failure is easy to occur under the working condition of high-speed vibration. Along with the development of intelligent manufacturing, the limitations of the traditional discrete processing flow on information closed loop and production line beat are increasingly highlighted in the integrated upgrading of the fastener production line to digital quality inspection, online screening and automatic packaging. In view of the foregoing, there is a need in the art for an improved blind rivet nut solution capable of completing reverse stressed rivet turning in a limited space, having near-net forming capability of complex geometric features and matching with a high-efficiency multi-station cold heading device, so as to solve the outstanding problems in the aspects of installation adaptability, manufacturing efficiency, forming precision, assembly reliability and the like in the prior art. Disclosure of utility model In order to solve the technical problems, the utility model provides a reverse rivet nut and a forming device thereof. Specifically, the technical scheme provided by the utility model is as follows: The reverse rivet nut comprises a flange, a step and a conical rod part which are sequentially arranged along an axis, and is provided with a threaded hole penetrating through the flange, the step and the rod part along the axis, wherein the step is convexly arranged on the end face of the flange around the threaded hole, the outer round radius of the step is smaller than the outer round radius of the flange, a plurality of tendons are further arranged on the end face of the flange around the step, the conical rod part is convexly arranged on the end face of the step around the threaded hole, the radius of the conical rod part gradually increases along with the distance from the step, and a groove is formed between the outer wall of the conical rod part and the end face