Molding blade for pneumatic tire tread
A pneumatic tire tread has tread elements formed by circumferential and/or lateral grooves. At least one tread element has a sipe that devolves from a constant width sipe having a three dimensional aspect in at least a portion of the radially outer portion of the sipe to a wider width groove at the base of the tread feature.
1. A blade for molding a tire, the blade comprising a body with a longitudinal axis, the body comprising an inner portion, an outer portion and an intermediate portion located between the inner portion and the outer portion, wherein the inner portion is substantially straight in the longitudinal direction and has opposed, spaced apart sidewalls having a defined depth, and wherein the intermediate portion has an increasing width from the outer portion to the inner portion, and the outer portion is undulating in the longitudinal direction.
2. The blade of claim 1 wherein the outer portion has a width Wo in the range of 0.3 to 1 mm, and the inner portion has a width Wi at least 2.5 times Wo.
3. The blade of claim 1 wherein the inner portion of the blade is hollow.
4. The blade of claim 1 wherein the outer portion has a sinusoidal profile in the longitudinal direction.
5. The blade of claim 1 wherein the outer portion has a zigzag profile in the longitudinal direction.
6. The blade of claim 1 wherein the outer portion has a substantially straight cross-section in the radial direction.
7. The blade of claim 1 wherein the intermediate portion is undulating in the longitudinal direction.
8. The blade of claim 1 wherein the cross-sectional shape of the blade varies along the longitudinal length of the blade.
9. The blade of claim 7 , wherein an amplitude of the undulating portion of the intermediate portion decreases from the outer portion to the inner portion.