splined spring pin
The Grooved Pin Principle
The fastener incorporates in its design three longitudinal grooves swaged or formed into a cylinder of material, which has the effect of increasing its diameter. In the case of unheaded pins, this may be over part or all of the length of the pin and may be of a tapered or parallel form. In the case of Headed pins, the grooves are always parallel and, with Blind Drive Pin Rivets, the pin is used to expand the rivet and is retained in the body of the rivet.
In each product, installation of the grooved pin causes the grooves to compress, this compression produces outward pressure on the walls of the hole and in so doing secures location of the pin. Diagram 1 shows compression taking place as a section through a grooved pin.
When compared with more traditional taper pins, plain pins, keys or locating pins which rely on 'interference' at one point on the pin and also require a reamed or precision formed hole, the grooved pin principle can be seen to represent a significant improvement. Resistance to withdrawal occurs wherever the grooved diameter is compressed; it can be over the whole length of the pin instead of just at one point as with traditional pins. This advantage is represented in diagram 2.