Forming splice joints for elastomeric materials

Details Forming splice joints for elastomeric materials Forming splice joints for elastomeric materials

2001-06-25

2003-07-15

Osele, Mark A. (Department: 1734)

Adhesive bonding and miscellaneous chemical manufacture

Methods

Surface bonding and/or assembly therefor

C156S268000, C156S304100, C156S304500, C156S512000, C083S051000

Reexamination Certificate

active

06592704

ABSTRACT:

TECHNICAL FIELD
This invention relates to forming a segment of elastomeric material to a predetermined length having tacky splicing surfaces at each end of the segment, the segment being formed from a strip of elastomeric material. In particular, the formation of a combination of low angle skived splicing surface with an abutment surface at each end of the segment is taught.
BACKGROUND ART
Elastomeric materials, particularly those used in the manufacture of tires, belts and other such industrial products requiring vulcanization of the elastomer are well known for having tacky surfaces which can readily be stuck together particularly prior to being completely cured or vulcanized. It is this very tacky surface feature that has enabled manufacturers to assemble various elastomeric components together in layers or composites of different shapes or compound materials without requiring additional adhesives or cements.
This pre-assembly of components is most common in the tire industry wherein layers of elongated elastomeric strips are cut to length and cylindrically wound and spliced upon a first stage building drum prior to being toroidally shaped and placed in a vulcanizing curing press.
Often the strips are formed from a homogeneous single elastomeric compound. Alternatively strips of tire components can be formed of multiple layers or composites having differing materials. Often one or more of the strips of tire components may have elastomeric material with reinforcing cords or fibers.
With the need to increase manufacturing efficiency, many of these strips of tire components are now formed as subassemblies or laminates having many components pre-assembled in sheets or strips of material as is described in U.S. Pat. No. 5,762,740. These laminated elastomeric materials when used are cut from elongated strips. In some cases the strips are sufficiently thick to permit the cut ends to be jointed in an abutting relation commonly referred to as butt splicing. Often the strips are cut on a skive angle and the ends are spliced as close as possible along the cut surfaces as is described in U.S. Pat. Nos. 5,746,101 and 5,746,102.
One advantage of butt splices are the cut to length segment has easy to detect ends making it possible to make a splice with no overlapping material. In the manufacture of tires, overlapping ends of material create mass distribution irregularities that can affect the ride and handling performance of the resultant tire. Butt splice's one major drawback is the lack of adhesion at the joint due to the minimal contact area at the joint. Accordingly, butt splices can separate or disjoin at the splice during the shaping or curing of the tire if a sufficient surface area or thickness is not available. In those cases a splicing strip of gum rubber can be overlaid onto the splice joint again creating a mass distribution problem.
Skive cut surfaces or simply very thin strips are often lap spliced. In such a case, the components cut ends overlap slightly to provide increased surface area for joint adhesion. While lap splicing yields very good joint adhesion, the very existence of these joints contribute to tire non-uniformities such as sidewall undulations, uneven tread wear and tire imbalances as discussed above.
One of the most promising solutions to these problems is to provide splicing surfaces of sufficient area to enhance joint adhesion. The most promising solution has been to provide low angle skiving which forms cut angles less than 30 degrees relative to the plane of the material. This technique is particularly useful in strips of material having a moderate to thick cross-section such as the multi-layered laminates or composites. Such a technique of very low angle cutting is disclosed in PCT Application No. PCT/98/10387.
In cutting a non-reinforced tread strip for example it is relatively easy to achieve low skive angle cuts. Alternatively, low angle skive cutting cord reinforced strips or elastomeric composites with at least one layer of parallel cords can be much more difficult requiring special cutting techniques as disclosed in U.S. Pat. Nos. 5,746,101 and 5,746,102.
One of the problems associated with low angle cutting has been that it is not easy to align the cut ends, precisely. Unlike the butt splice, there is no clear indication when the cut ends are aligned. Low skive angle cuts are neither readily observable nor detectable as they are being joined. The one cut end when being attached to the other end obstructs the view. The stitched together joint is either overlapping or slightly underlapping. The very thin tips of the low angle skive cuts are easily deformed and damaged while the interior portion of the cut surface is barely discernable from the uncut surface, for these reasons the tire builder whether a man or an automated machine has a somewhat difficult time achieving a precise strip joint.
As a general rule the strip has a cut length slightly smaller than required which enables the strip to be stretched locally at the joint. This localized stretching can result in non-uniform cord spacing in the resultant tire. An example of splicing an elastomeric joint from a strip of elastomeric material can be found in U.S. Pat. No. 5,273,601. Stretching of strips to make a joint insures that entrapped air and ply or strip wrinkling is avoided. If the strip has parallel cords, as in the example of a radial ply used in the manufacture of a tire, localized stretching can change the cord spacing creating another non-uniformity. It is most important to note that uniformity is generally always desirable and that non-uniformities are almost always something to be avoided or eliminated in the manufacture of a tire splice.
The conventional wisdom in the manufacture of tires for example is that the number of splices should be minimized and if required at all the splices should be staggered around the circumference to minimize localized non-uniformities when multiple splices are circumferentially aligned.
One of the objects of the present invention is to provide a spliced joint that has a strip with ends that are easily and precisely located by employing a method and an apparatus for forming single or multi-component segments of elastomeric material of a predetermined length having ends exhibiting low angle splice surfaces for joint splicing in combination with abutment surfaces that are readily detectable by the tire builder.
Another object of the invention is to provide a method and apparatus that precisely achieves the same uniform joint repeatably and predictably wherein the strip of elastomeric material can be formed of a predetermined length without requiring the necessity of over stretching the strip.
Another object of the invention is to provide the above-mentioned splice joint on strips of material that have variations in cross-sectional thickness across the width of the strip or in flat strips having uniform thickness whether the strip is made of a single elastomeric material or a multi-layered components of different material compounds some of which may contain at least one layer of parallel cords oriented in a similar direction.
DISCLOSURE OF INVENTION
SUMMARY OF THE INVENTION
A method for forming a segment (
10
) of elastomeric material of a predetermined length L
1
having tacking splicing surfaces (
6
) at each end (
12
,
14
) from a strip (
1
) of elastomeric material is disclosed. The strip (
1
) has a length L, a width W, a maximum thickness t as measured across the width of the cross-section, a first side (
2
) and an opposite second side (
4
).
The method has the steps of a) forming a low angle skive surface (
6
) across the width W of the strip (
1
). The low angle skive surface (
6
) extends from a first side (
2
) of the strip (
1
) to a predetermined depth (d), (d) being less than the maximum thickness t of the strip (
1
); b) forming an abutment surface (
8
), the abutment surface (
8
) extending from the opposite second side (
4
) of the strip (
1
) across the width W of the strip (
1
) in a path substantially parallel to the low skive an

Affiliated with

Also associated with

Rating

Forming splice joints for elastomeric materials does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Forming splice joints for elastomeric materials, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Forming splice joints for elastomeric materials will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3035996