A heatstake for fastening a workpiece includes a base portion ( 12 ) having at least one shaft portion ( 22 ). A central passage ( 30 ) extends though the shaft portion from its leading end ( 28 ) to the base portion. A plurality of slots ( 22 ) are disposed about an outer surface ( 34 ) of the shaft portion ( 22 ). The plurality of slots ( 32 ) have a predefined angular separation. Preferably, the plurality of slots ( 32 ) disposed about the outer surface of the shaft portion form a heatstake having multiple fastening portions. The multiple fastening portions are adapted to form a geometric flower shape for increasing the fastening strength of a heatstake when staked.
1. A heatstake fastener for fastening at least two workpieces, comprising:
first and second concentrically disposed shaft portions, the first shaft portion having a leading end and a length greater than a length of the second shaft portion, wherein said second shaft portion is adapted to be received in a hole defined in one of the workpieces;
a central passage extending through the first and second shaft portions; and
a plurality of slots disposed about an outer surface of the second shaft portion having a predefined angular separation, the plurality of slots defining a plurality of fastening portions when the second shaft portion is deformed, whereby the fastening portions are adapted to conform to a surface of the one of the workpieces beyond a perimeter of the hole,
wherein the first shaft portion applies pressure against the fastening portions of the second shaft portion when the first shaft portion is deformed, and
wherein said fastening portions of said second shaft portion engages said one of the workpieces when said second shaft portion is deformed.
2. The heatstake according to claim 1 wherein the plurality of slots comprises at least three slots.
3. The heatstake according to claim 2 , wherein the predefined angular separation is approximately 120 degrees.
4. The heatstake according to claim 1 , wherein the fastening portions of the second shaft portion form a geometric configuration in the form of a rosette or flower shape.
5. The heatstake according to claim 1 , wherein said first and second shaft portions define a gap therebetween.
6. The heatstake according to claim 1 , wherein said first and second shaft portions are made of thermoplastic material.
7. The heatstake according to claim 1 , wherein the heatstake fastener extends from another one of the at least two workpieces.
8. A heatstake fastener for fastening at least two workpieces, comprising:
a first shaft portion including a first leading end and a first central passage;
a second shaft portion adapted to be received in a hole defined in one of the workpieces, said second shaft portion including a second leading end, a second central passage, and a plurality of slots disposed about an outer surface having a predefined angular separation, the plurality of slots defining a plurality of fastening portions when the second shaft portion is deformed, whereby the fastening portions are adapted to conform to a surface of the one of the workpieces beyond a perimeter of the hole,
wherein the first shah portion is generally concentrically disposed about the second central passage of the second shaft portion such that the first shaft portion applies pressure against the fastening portions of the second shaft portion when the first shaft portion is deformed, and
wherein said fastening portions of said second shaft portion engages said one of the workpieces when said second shaft portion is deformed.
9. The heatstake according to claim 8 , wherein the first shaft portion has an outer diameter less than an inner diameter of the second shaft portion.
10. The heatstake according to claim 8 , wherein the plurality of slots comprises at least three slots.
11. The heatstake according to claim 10 , wherein the predefined angular separation is approximately 120 degrees.
12. The heatstake according to claim 8 , further comprising a gap between an outer diameter of said first shalt portion and an inner diameter of said second shaft portion.
13. The heatstake according to claim 8 , wherein said first and second shaft portions are made of thermoplastic material.
14. The heatstake according to claim 8 , wherein the heatstake fastener extends from another one of the at least two workpieces.
15. A method of deforming a heatstake fastener for fastening at least two workpieces in a controlled fashion, the heatstake comprising a base portion, first and second concentrically disposed shaft portions, the first shaft portion having a leading end and a length greater than the second shaft portion, a central passage extending through the first and second shaft portions, the second shaft portion adapted to be received in a hole defined in one of the workpieces; and a plurality of slots disposed about an outer surface of the second shaft portion having a predefined angular separation, the plurality of slots defining a plurality of fastening portions when the second shaft portion is deformed, the method comprising the steps of:
deforming the first shalt portion vertically downward and radially outward about a vertical axis of the first shaft portion such that the first shaft portion positively engages the one of the workpieces, and
deforming the second shaft portion such that the fastening portion of the second shaft portion positively engages the one of the workpieces whereby the fastening portions conform to a surface of the one of the workpieces beyond a perimeter of the hole.
16. The method according to claim 15 , wherein the fastening portions define a geometric configuration in the form of a rosette or flower shape.
17. The method according to claim 15 , further comprising a gap between an outer diameter of said first shaft portion and an inner diameter of said second shaft portion.
18. The method according to claim 15 , wherein said first and second shaft portions are made of thermoplastic material.
19. The heatstake according to claim 15 , wherein the heatstake fastener extends from another one of the at least two workpieces.