Clinching punch and apparatus
A clinching apparatus includes a clinching punch having a specifically dimensioned tapered surface which improves the strength of a clinch joint created therewith. In another aspect, a tapered surface adjacent a distal end of a clinching punch has an angle of 20-35° relative to a distal end. A further aspect of a clinching apparatus provides a tapered surface adjacent a distal end which is configured in accordance with a specific formula.
1. A clinching apparatus comprising:
a linearly movable clinching punch including a side and an end, a taper located between the side and the end, the taper having an angle of 20-35 degrees relative to the end and the taper including an annular end view shape;
the side, which is adapted to form an inside cavity of a clinch joint, being free of any step thereon;
a holder secured to a proximal end of the punch;
a stripper located adjacent a portion of the punch;
a resilient member biasing the stripper away from the holder;
a clinching die including a central anvil coaxially aligned with the punch, and upstanding die blades surrounding the anvil; and
a clinch joint in multiple sheet metal workpieces created between the punch and the die;
wherein the side and taper are dimensioned according to:
E
=
B
2
-
P
thk
2
(
1
tan
F
)
where 2E is a minor diameter of the side where the taper intersects the end, B is a major diameter of the side where the taper intersects the side, P thk is a nominal punch side-workpiece material thickness, and F is the angle of the taper.
2. The clinching apparatus of claim 1 , wherein the multiple sheet metal workpieces are multiple appliance workpieces.
3. The clinching apparatus of claim 1 , wherein:
the multiple sheet metal workpieces are sheet steel workpieces; and
an inside corner of the clinch joint includes a frusto-conical taper.
4. The clinching apparatus of claim 1 , wherein the multiple sheet metal workpieces are sheet aluminum.
5. The clinching apparatus of claim 1 , wherein the angle of the taper is 28-32 degrees relative to the end.
6. The clinching apparatus of claim 1 , wherein the clinching end of the punch facing the die has a first peripheral diameter less than half of a second peripheral diameter of the proximal end of the punch opposite that of the clinching end.
7. The clinching apparatus of claim 1 , wherein the multiple sheet metal workpieces are sheet steel workpieces of differing thicknesses clinched together by the punch and the die, and the clinch joint formed therebetween withstanding a peel force of at least twenty-five pounds, the workpieces being part of a washer or dryer appliance.
8. A clinching apparatus comprising:
a linearly movable clinching punch including a side and an end, a taper located between the side and the end, the taper having an angle of 20-35 degrees relative to the end and the taper including an annular end view shape;
a stripper located adjacent a portion of the punch;
a resilient member biasing the stripper;
a clinching die including a central anvil coaxially aligned with the punch, and upstanding die blades surrounding the anvil; and
a clinch joint in multiple sheet metal workpieces created between the punch and the die;
wherein the side and taper are dimensioned according to:
E
=
B
2
-
P
thk
2
(
1
tan
F
)
where 2E is a minor diameter of the side where the taper intersects the end, B is a major diameter of the side where the taper intersects the side, P thk is a nominal punch side-workpiece material thickness, and F is the angle of the taper.
9. The clinching apparatus of claim 8 , wherein the multiple sheet metal workpieces are multiple appliance workpieces.
10. The clinching apparatus of claim 8 , wherein:
the multiple sheet metal workpieces are sheet steel workpieces; and
an inside corner of the clinch joint includes a frusto-conical taper.
11. The clinching apparatus of claim 8 , wherein the multiple sheet metal workpieces are sheet aluminum.
12. The clinching apparatus of claim 8 , wherein the angle of the taper is 28-32 degrees relative to the end.
13. The clinching apparatus of claim 8 , wherein the clinching end of the punch facing the die has a first peripheral diameter less than half of a second peripheral diameter of the proximal end of the punch opposite that of the clinching end.
14. The clinching apparatus of claim 8 , wherein the multiple sheet metal workpieces are sheet steel workpieces of differing thicknesses clinched together by the punch and the die, and the clinch joint formed therebetween withstanding a peel force of at least twenty-five pounds, the workpieces being part of a washer or dryer appliance.
15. The clinching apparatus of claim 8 , wherein the anvil is stationary relative to a surrounding cylindrical shield, and the die blades are moveable relative to the anvil and the shield.
16. The clinching apparatus of claim 8 , wherein at least one of the workpieces is pre-painted prior to clinching contact between the punch and the die.