Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
1999-03-24
2003-05-20
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209230, C152SDIG003, C425S028100, C425S035000, C425S046000
Reexamination Certificate
active
06564840
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a lamella for use in vulcanization molds for producing a vehicle tire. The lamella has projections and depressions extending substantially parallel to the peripheral surface of the tire tread of the vehicle tire to be produced. Each projection has a highest point-shaped location and each depression has a lowest point-shaped location whereby the projections and the depressions are substantially arranged in a uniform area division. The areal division is defined by linear (line-shaped) dividing lines positioned preferably centrally between the highest point-shaped locations and the lowest point-shaped locations. The dividing lines are comprised of sets whereby the dividing lines within each set extend parallel to one another and the dividing lines of different sets intercept one another. The projections may also have a line-shaped (linear) highest location while the depressions still have a lowest point-shaped location or, in the alternative, each projection may have a highest point-shaped location while the depression has a line-shaped (linear) lowest location. In this case, the dividing lines are either positioned at the highest line-shaped location or the lowest line-shaped location.
The present invention also relates to a vulcanization mold having lamellas as disclosed above.
Also, the invention relates to a vehicle tire having a tire tread with sipes that are produced by lamellas embodied as disclosed above.
The inventive lamella is to be used in vulcanization molds (
2
) whereby such vulcanization molds (
2
) are used for producing vehicle tires (
3
). The inventive lamellas are arranged in the area of the tire tread to be molded in order to produce in the tire tread sipes having a design that matches, with the exception of minimal uniform shrinkage, the negative pattern of the lamella design.
Even though the greatest economic value of the invention lies within the inventive vehicle tire with the novel sipes, in the present application the inventive lamella will be disclosed first because with it the complicated special shape of the lamella of the present invention can be more easily shown than the sipes of a tire tread.
Even though the rubber mixture of the tire tread during molding of the sipes by lamellas is still plastic and shrinkage of the rubber during cooling from the vulcanization temperature to the tire operating temperature is minimal and is substantially uniform in all three special directions, the design of the sipe matches substantially exactly the shape of the lamella that has produced this sipe. The sipe and the lamella producing this sipe behave, with the exception of minimal shrinkage, as a positive and a negative pattern so that their edges are substantially inverse congruent, i.e., each body edge of the lamella projecting counter to a direction of viewing has a negative edge extending in the same direction which is a avoid area edge within the same projection counter to that same direction of viewing and each body edge of the lamella with a projection in the direction of viewing has a negative edge extending in the same direction within the same projection. This means that by disclosing the shape of the lamella the shape of the sipes in the tire is also disclosed.
It is known that such sipes in tire treads serve to soften the tire tread and also provide edge formation in order to thus increase grip on slippery surfaces. Such sipes are especially used in large numbers for snow tires.
It is also known that the degree of softening depends approximately with the third power from the depth of the sipe. This results in the problem for smooth sipes that the cut tread surface when the tire is new, especially when a sipe depth is identical to the depth of the tread grooves, the tread surface is unnecessarily soft and has an unnecessary degree of edge formation with disadvantages during dry handling, respectively, with respect to wear.
Even though a reduced depth of the sipes eliminates such disadvantages, another disadvantage is produced, i.e., after wear of a tread depth corresponding to the reduced sipe depth, sipes are no longer present. Accordingly, the tire will loose its grip on slippery surfaces.
An improved solution is known according to which for a full sipe depth the effectiveness of the areas located deep within the sipe is greatly limited in that the sipes are wave-shaped or curved so that positive-locking engagement between the closely positioned walls of the same sipe will result. According, only small radially outer areas of the sipes are effective whereby these effective areas with increased wear will move radially inwardly so that the softening effect, by propagation of the effective deformation base to the actual sipe base, will fluctuate less.
Conventionally sipe widths in car tires are between 0.4 to 1.0 mm, whereby especially the width of approximately 0.6 mm is used for car tires. Car tires are the preferred application of the invention. Inasmuch as such sipes are used for truck tires, commercial truck tires or even heavy truck tires, the required width increases approximately with the root of the suggested tire pressure and linear with the depth of the tire tread. For heavy truck tires with approximately four times the tire pressure and twice the tread depth, suitable sipe widths are between 1.6 and 4.0 mm, preferably 2.4 mm.
The known suggestions, to provide after a limited deformation travel positive-locking engagement as a function of the width of the sipe, can be divided into three groups.
A first group comprises the suggestions of wave-shaped sipes. In contrast to the aforementioned depressions and projections of the prior art, upon which the inventive design is based, all projections have a line-shaped (linear) highest location, usually referred to as a peak, even more precisely referred to as a crest (BK), and all depressions have a line-shaped (linear) lowest location, usually referred to as a valley, even more precisely referred to as a valley bottom (TS). Such suggestions can be taken from
FIG. 2
of French Patent 791 250, European Patent application 0 564 4 35, German Patent application 44 27 895, Austrian Patent 401 160 and still unpublished German Patent applications 196 50 702.2 and 197 10 400.2 whereby the latter shows crests and valleys that are curvilinear while the others show straight lines or angled lines.
A second group includes suggestions having curved sipes wherein all projections have a line-shaped (linear) highest location and all depressions have a point-shaped lowest location or visa versa. Such a suggestion is disclosed in Great Britain patent 1,150, 295.
A third group includes suggestions having sipes that are curved such that all projections have a point-shaped highest location, referred to as a top (G), and all depressions (
5
) have a point-shaped lowest location, referred to as a crater (K). This is disclosed in published PCT document WO 96/01189. Based on the conventional mounting of the lamellas in the vulcanization mold, such that the produced sipes in the tire tread extend substantially axially and radially, the measuring direction for the height of the projections and the depth of the depressions extends thus substantially parallel to the peripheral surface of the tire tread of the produced vehicle tire. The depth of the depression is to be understood as a negative height. Accordingly, for the deformation height and deformation depth (more precisely the dimple depth) the same reference numeral can be used: Z.
In all suggestions of the prior art the crests or peaks of a sipe, respectively, of a lamella are positioned in a common plane and at the same time all valleys or craters of the same sipe, respectively, of the same lamella are positioned in another common plane whereby both planes extend parallel to one another. At least for the suggestions of the first and third group, it appears to be expedient to define a reference plane between these two planes. The reference plane is used to measure the deformation heights and depths, and it is re
Beckmann Otto
Kleinhoff Klaus
Becker R W
Continental Aktiengesellschaft
Maki Steven D.
R W Becker & Associates
LandOfFree
Lamella of high stability for a vulcanization mold,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lamella of high stability for a vulcanization mold,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lamella of high stability for a vulcanization mold,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3017739