Hook fastener with cap cavity
A hook fastener includes a stem having two lateral edges, a first surface, and a second surface. A cap extends from an upper end of the stem, and the cap includes an upper surface, a first end, a second end, and a pair of overhanging portions. The upper surface of the cap is sloped between the first end and the second end. The first and second ends are at opposite longitudinal ends of the cap, and each overhanging portion extends in a lateral direction from the stem.
1. A hook fastener comprising:
a base surface;
a stem extending from the base surface;
a cap that extends from an upper end of the stem, the cap comprising:
an upper surface, a first end, a second end, and a pair of overhanging portions,
wherein:
the first and second ends are disposed at opposite longitudinal ends of the cap;
each of the pair of overhanging portions extends in a lateral direction from the stem,
the cap comprises a cavity on an underside of the second end of the cap near an interface between the cap and the stem, the cavity extending toward an interior of the hook fastener and toward the first end of the cap, and
the cap is distorted and configured so that portions of the cap adjacent to the first end are curled and/or everted.
2. The hook fastener of claim 1 , wherein the cavity forms an acute angle at an interior-most point.
3. The hook fastener of claim 1 , wherein the cavity comprises a wide opening near each of two lateral ends of the stem and a narrow opening near a center of the stem.
4. The hook fastener of claim 1 , wherein the first end of the cap is thicker than the second end of the cap.
5. The hook fastener of claim 1 , wherein the pair of overhanging portions comprises a first overhanging portion extending in a first lateral direction and a second overhanging portion extending in a second lateral direction opposite the first lateral direction.
6. The hook fastener of claim 5 , wherein each of the first and second overhanging portions comprises an open region disposed underneath the overhanging portion configured to engage a loop attachment structure.
7. The hook fastener of claim 5 , wherein each of the first and second overhanging portions comprises an underside surface that includes a generally flat portion that is approximately parallel to the base surface.
8. The hook fastener of claim 1 , wherein each of the pair of overhanging portions comprises a tip end portion arranged at an outermost point in the lateral direction, a first periphery edge at a side of the first end with respect to the tip end portion, and a second periphery edge at a side of the second end with respect to the tip end portion, and wherein a length of the first periphery edge is less than a length of the second periphery edge.
9. The hook fastener of claim 8 , wherein if the pair of overhanging portions are divided by a line passing through each tip end portion and being approximately parallel to the lateral direction to separate the pair of overhanging portions into (i) a first area of the first end of the cap and (ii) a second area of the second end of the cap, the first area is smaller than the second area.
10. The hook fastener of claim 8 , wherein a portion of the first periphery edge has a radius of curvature that is less than a radius of curvature of a portion of the second periphery edge.
11. The hook fastener of claim 8 , wherein the first periphery edge comprises a portion that extends generally linearly in the lateral direction from a contact point with the stem toward the tip end portion and the second periphery edge comprises a radius of curvature from a contact point with the stem to the tip end portion.
12. The hook fastener of claim 8 , wherein the first periphery edge comprises a first radius of curvature that curves at least partially in a direction opposite of the second end and the second periphery edge comprises a second radius of curvature that is larger than the first radius of curvature.
13. The hook fastener of claim 1 , wherein the upper surface of the cap is sloped between the first end and the second end.
14. The hook fastener of claim 1 , wherein the upper surface of the cap is an irregular surface.
15. The hook fastener of claim 1 , wherein the cap includes one or more protrusions defining a maximum thickness which is greater than a thickness of other portions of the cap.
16. The hook fastener of claim 15 , wherein the one or more protrusions form one or more local peaks in the upper surface of the cap.
17. The hook fastener of claim 1 , wherein one or both of the overhanging portions are thicker in a vertical direction than a central portion of the cap.
18. The hook fastener of claim 1 , wherein a central portion of the upper surface of the cap is recessed relative to the first end and the second end.