Rivet for friction self-piercing riveting and friction self-piercing riveting connection system thereof

Patent metadata

Field	Value
Publication number	US-10695821-B2
Application number	US-201716068637-A
Country	US
Kind code	B2
Filing date	Jun 23, 2017
Priority date	Jul 19, 2016
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A rivet rotational feeding method for friction self-piercing riveting (F-SPR) system, comprising: a semi-hollow rivet, a driving spindle and a die. The bottom surface of the rivet head is connected to the semi-hollow rivet shank. The semi-hollow rivet shank has a wedge-shaped end. The rivet head has rotation driving structures and positioning structure on the top end. The rotation driving structures are central symmetric concave or convex surfaces. The positioning structure is a central symmetric and mirror symmetric concave or convex surface. The matching between the driving spindle and the rivet can improve the rotation reliability and positioning accuracy of the riveting at a high rotational speed during F-SPR process, which is beneficial to solve the problems of poor stability and non-coincidence between the geometry axis and the rotation axis of the rivet.

First claim

What is claimed is:

1. A friction self-piercing rivet (F-SPR), comprising:
a semi-tubed rivet shank, with a wedge shaped cone tip at its bottom end, wherein
the rivet has a rivet head that connecting with an upper end of the rivet shank;
the rivet head has a chamfering and rotary driving structures at its upper end, and a positioning structure in its center;
the rotary driving structure is a central symmetric, concave or convex surface;
the positioning structure is a central symmetric and mirror symmetric, concave or convex surface;
wherein the rotatory driving structure has several wedge-shaped notches, plum blossom shaped bosses or a plum blossom shaped grooves evenly distributed along a circumferential direction of the rivet head; the wedge-shaped notch has two intersecting planes, one of which is perpendicular to surface of the rivet head, designed for bearing a circumferential torque, and other one is tilted from the surface of the rivet head to lower end of the rivet head for dynamic matching; the plum blossom shaped bosses contain several petals evenly distributed along circumferential direction of the rivet head, which are used to bear circumferential torques; and the plum blossom shaped grooves contain several petals evenly distributed along circumferential direction of the rivet head, which are used to bear circumferential torques;
wherein the concave or convex surface of the rotatory driving structure is a non-mirror symmetric structure.

2. The friction self-piercing rivet of claim 1 , wherein the tip has a vertex conforming to an inner wall or an outer wall of the rivet shank or between the inner wall and the outer wall of the rivet shank.

3. The friction self-piercing rivet of claim 1 , wherein the positioning structure is a cone shaped groove or a conical protruding platform.

4. The friction self-piercing rivet of claim 3 , wherein the cone shaped groove is coaxial with a semi-hollow rivet shank to ensure that a rotation axis of the rivet is coincided with its geometric axis when a driving torque is applied.

5. The friction self-piercing rivet of claim 3 , wherein the conical protruding platform is coaxial with a semi-hollow rivet shank to ensure that the rotation axis of the rivet is coincided with its geometric axis when a driving torque is applied.

6. A friction self-piercing riveting (F-SPR) system comprising:
a driving spindle that is capable of driving a rivet for axial translational motion and circumferential rotational motion;
a rivet comprising:
a semi-tubed rivet shank, with a wedge shaped cone tip at its bottom end, wherein
the rivet has a rivet head that connecting with an upper end of the rivet shank;
the rivet head has a chamfering and rotary driving structures at its upper end, and a positioning structure in its center;
the rotary driving structure is a central symmetric, concave or convex surface;
the positioning structure is a central symmetric and mirror symmetric, concave or convex surface;

a die on the bottom of a workpieces;
wherein a driving spindle has a lower surface matching with an upper surface of the rivet head;
wherein the matching is:
{circle around (1)} when a rotatory driving system is in the form of several wedge-shaped notches, the driving spindle has several wedge-shaped projections evenly distributed along a circumferential direction on bottom;
wherein the number of wedge-shaped projections is equal to the number of the wedge-shaped notches;
wherein the shape of the wedge-shaped projections is complementary to the shape of the wedge-shaped notch, and:
{circle around (2)} when the positioning structure is cone-shaped groove, the driving spindle has a positioning protruding on bottom;
wherein the positioning protrusion has a same taper with the positioning grooves;
wherein the positioning protrusion has a height smaller than the depth of the positioning groove.

7. The F-SPR system of claim 6 , wherein the wedge-shaped notch and wedge-shaped protrusion have chamfering on each edge for avoiding over positioning.

8. The F-SPR system of claim 6 , wherein the die has an upper surface designing with fixed structures on top end to control plastic flow of the workpieces in riveting.

9. The F-SPR system of claim 8 , wherein the fixed structure includes a die with a flat surface, a pip die, a die with a concave flat bottom and a die with a through hole.

10. The F-SPR system of claim 6 , wherein a process for rivet rotational feeding includes:
Step 1, placing the rivet vertically under the driving spindle and applying appropriate resistance to restrain an axial translational motion and rotational motion of the rivet;
Step 2, feeding the driving spindle straightly downwards to the upper surface of the rivet;
Step 3, feeding the driving spindle axially downward slowly and, at the same time, rotating the driving spindle to match the positioning structure of the driving spindle automatically with the positioning structures in the center of the rivet head; making the rotary driving structures on bottom of the driving spindle contacting with the driving structures on the top of the rivet head; the surfaces of the rivet head and on the driving spindle contact with each other, wherein bottom surface of the driving spindle contact with the top surface of the rivet head;
during the mating of the driving spindle and the rivet, when an axial pressing force or a circumferential torque exerted on the rivet by the driving spindle exceeds external resistance applied to the rivet, the rivet starts to move axially or circumferentially with the driving spindle;
Step 4, when the driving spindle and the rivet move together approaching the surface of the workpieces, speed of the axial and circumferential motion of the driving spindle switch to required process parameters of F-SPR process and drive the rivet to finish the F-SPR process under setting process parameters.

Assignees

• Univ Shanghai Jiaotong

Inventors

• Li Yongbing
• Ma Yunwu
• Lou Ming
• Lin Zhongqin

Classifications

• B21K25/005

  by friction heat forging (B21J15/027 takes precedence; friction heat forging per se B21J5/063) · CPC title

• B21J15/12

  with tools or tool parts having a movement additional to the feed movement, e.g. spin {(B21J15/027 takes precedence)} · CPC title

• B21J5/063

  Friction heat forging (friction heat riveting B21J15/027) · CPC title

• B23P23/04 Primary

  for both machining and other metal-working operations · CPC title

• B21J15/025

  Setting self-piercing rivets · CPC title