Patent Application
20070175010
The present invention relates to an improved method for blind riveting together a set of members.
It is known to attach together a set of members using a blind rivet assembly. The use of a blind rivet to attach members together is particularly useful in the assembly or repair of vehicle bodies or other applications in which access can be obtained to only one side of one of the members (a top member), with the other member (a bottom member) being hidden and inaccessible below the top member.
It would be desirable to provide improvements in the blind rivet method of attaching members together. For example, improvements to make such attachments more reliable by electronically monitoring the installation of the blind rivet.
Apparatus is provided for monitoring the attachment together of top and bottom members by the installation of a blind rivet of the type having a rivet head abutting the top member and a hollow shank reaching through aligned holes of the top and bottom members and having a terminal end, and a mandrel including a stem extending through the hollow shank of the rivet and a mandrel head adjacent the terminal end of the rivet shank. A tool housing has an anvil seated on the rivet head. A collet is reciprocable within the tool housing and carries jaws for gripping the mandrel. Retraction of the jaws by the collet displaces the jaws and the mandrel axially and causes the mandrel head to axially collapse and radially expand the hollow shank of the blind rivet into engagement with the bottom member so that the rivet attaches the top member and the bottom member. A first transducer measures the axial load imposed on the mandrel. A second transducer measures the axial displacement of the collet and the jaws and the mandrel therewith.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
Referring to
A hole 14 is drilled, pierced, or otherwise provided through the top member 10 and an aligned hole 16 is provided in the bottom member 12.
A blind rivet assembly 18 is inserted through the aligned holes 14 and 16. The blind rivet assembly 18 includes a blind rivet 22 and a mandrel 24.
The blind rivet 22 has a rivet head 26 and a hollow rivet shank 28 that are integrally formed in one piece. The rivet head 26 rests on the top face 30 of the top member 10. The hollow rivet shank 28 extends through the aligned holes 14 and 16 and is somewhat longer than the combined thickness of the top and bottom members 10 and 12 and has terminal end 32 that ends somewhat beyond the bottom face 34 of the bottom member 12.
The mandrel 24 includes a stem 38 that extends through the blind rivet 22 and has an enlarged mandrel head 40 at its terminal end. As seen in
Referring to
The upper end of the collet sleeve 52 is attached to a drive shaft 62 by threads 64. The drive shaft 62 is connected to an operating mechanism, such as a pneumatic cylinder, hydraulic cylinder, electric motor, or the like, for forcibly reciprocating the collet sleeve 52 within the tubular tool housing 46.
The lower end of the collet sleeve 52 is partly closed by an end wall 66 that is normally engaged by the lower end of the collet sleeve 52 as shown in
As seen in
In
In
A monitoring system for monitoring the installation tool includes a displacement sensor 86 that measures the displacement of the collet sleeve 52, a load cell washer 88 that measures the axial load imposed upon the mandrel stem 38, and an electronic controller 90.
More particularly, the displacement sensor 86 is preferably a linear variable differential transformer that is mounted on the tool housing 46 and has a spring loaded plunger 92 that follows an arm 94 that projects from the side of the collet sleeve 52. Alternatively the transducer 86 may be a commercially available optical displacement sensor. The transducer 86 is electrically connected to the electronic controller 90 by a cable 96.
The load cell washer 88 is interposed between the lower end of the collet sleeve 52 and the anvil housing 70. It will be understood that as the jaws 56 and 58 and the collet sleeve 52 forcibly lift the mandrel stem 38 upwardly, there is an equal and opposite reaction force that is imposed upon the anvil housing 70 and is sensed by the load cell washer 88. The load cell washer 88 is connected to the electronic controller 90 by a cable 98.
Referring to
It will be understood and appreciated that the electronic controller 90 will monitor the mandrel displacement and axial force during the conduct of the blind rivet installation process and may perform any of a number of monitoring and control functions as shown in the flow chart of
It will be understood that the foregoing description of the invention is merely exemplary in nature and, thus, variations thereof are intended to be within the scope of the invention. For example, the drawings show sensors for sensing both displacement and force. However, it may be found useful to monitor either one of these conditions, without the other. In addition, other known displacement transducers and force measuring transducers may be substituted for those specifically described herein. Furthermore, although the drawings show the load cell as associated with the anvil, it may be desirable to mount the load cell with the drive shaft or the collet sleeve to measure the force applied to the mandrel by the installation tool. And although the drawings show only a top member and bottom member being attached by the blind rivet, the monitoring system of this invention can also be used when three or more members or components are stacked together.
