IP Library › Granted Patent US 8,616,039
Granted Patent B2
US 8,616,039 · App. 13/608,209 · Granted Dec 31, 2013

Method of manufacturing a clinch pin fastener

View Patent ↗
Loading inventors, assignments & file history…
Monitor This Case
Get email alerts when status or documents change.
Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 8,616,039
App. No.
13/608,209
Granted
Dec 31, 2013
Kind
B2
Abstract

A clinch-type fastener is formed by simultaneously creating an undercut during the same forging that creates the head and displacer of the fastener. A fastener blank is compressed end-to-end between top and bottom dies whereby the axial compression of a blank causes the outward bulging of the shank at its midline. Simultaneously, a tapered end point and a tangential interference band are formed provided by a curvilinear-shaped bulge in the shank. As the bulge is formed an undercut is created between the bulge and a shoulder which extends downwardly from a head of the fastener. This method of formation and the fastener produced thereby are particularly suited to the manufacture of small clinch pins having a diameter in the range of 1.0 mm.

Claims (10)

1. A method of manufacturing by cold-forging a free-standing metal fastener comprising:

providing a clinch pin fastener blank having a head, a shoulder and a shank of reduced diameter in that order top to bottom;

compressing end-to-end the fastener blank only between a top die and a bottom die whereby the axial compression of the blank causes the outward bulging of the shank at a midline thereof; and

continuing said compression until an undercut is formed contiguously between the bulge and the shoulder.

2. The method of claim 1 wherein said bulge is an arcuate surface in the middle of said shank.

3. The method of claim 1 wherein said bottom die includes a cone-shaped pocket for receiving said fastener blank.

4. The method of claim 3 wherein said cone-shaped pocket has a divergent side surface angle of 30°.

5. The method of claim 3 wherein said bottom die pocket further includes a centered upward projection.

6. The method of claim 1 wherein the length of the fastener blank shank is within a selected slenderness ratio range such that said fastener bulges when formed and does not buckle during the step of compressing the fastener blank.

7. The method of claim 6 wherein the length of the fastener shank is within a selected slenderness ratio less than √(2×π 2 ×E)/( y), where E is the modulus of elasticity and y is the yield stress for the shank material.