Method for producing webs for reinforcement ply of a tire by butt-joining straight-wire strips

Patent metadata

Field	Value
Publication number	US-11420405-B2
Application number	US-201816767243-A
Country	US
Kind code	B2
Filing date	Nov 30, 2018
Priority date	Dec 1, 2017
Publication date	Aug 23, 2022
Grant date	Aug 23, 2022

Abstract

The present invention relates to a method for manufacturing webs (1) that are intended to be involved in the makeup of a reinforcing ply (2) for a pneumatic tyre (20), said method comprising a preparation step (a), during which a plurality of straight-thread strips (7, 107, 207), which are each formed of a plurality of continuous reinforcing threads (4) that are embedded in a layer of rubber (5), are prepared, a butt-joining step (b), during which said straight-thread strips (7, 107, 207) are butt-joined in pairs to form a straight-thread ply (3), then a cutting step (c), during which the straight-thread ply (3) is inserted into a cutter (8) and the straight-thread ply (3) is severed transversely so as to form webs, wherein, in said method, the frontal width (W3) of the straight-thread ply (3) that is produced during the butt-joining step (b) and then inserted into the cutter (8) is equal to or greater than 50%, equal to or greater than 75%, equal to or greater than 80%, or even equal to or greater than 90%, of the cutter inlet width (W8), whereas the widest frontal width (W7, W107, W207) of the straight-thread strips is less than or equal to 50%, less than or equal to 40%, less than or equal to 25%, less than or equal to 10%, or even less than or equal to 5%, of said cutter inlet width (W8).

First claim

What is claimed is:

1. A method for manufacturing webs that are intended to be involved in the makeup of a reinforcing ply for a tire, said method comprises the following steps:
(i) a preparation step (a), during which a plurality of separate reels are prepared, each containing a strip, known as a “straight-thread strip”, which is formed of a plurality of continuous reinforcing threads that are embedded in at least one layer of rubber and extend parallel to one another in a longitudinal direction of said strip, each of said straight-thread strips having, perpendicularly to its reinforcing threads, a predetermined width known as the “frontal width”; then
(ii) a butt-joining step (b), during which the straight-thread strips contained on said plurality of separate reels are unwound simultaneously, and said straight-thread strips are butt-joined in pairs in one and the same common longitudinal direction, so as to combine all of said straight-thread strips into a straight-thread ply, the reinforcing threads of which extend in the common longitudinal direction, and which has, perpendicularly to said reinforcing threads, a straight-thread ply frontal width that is greater than the individual frontal width of each straight-thread strip; then
(iii) a cutting step (c), during which the straight-thread ply is inserted into a cutter that has a given maximum cutting capacity, known as the “cutter inlet width”, which corresponds to the largest frontal width of a straight-thread ply that can be inserted into the inlet of said cutter, then, by means of said cutter, the straight-thread ply is severed transversely, several times over, in a cutting direction that is secant to the direction of the reinforcing threads, so as to form portions of straight-thread ply known as “webs” of predetermined length;

and wherein the frontal width of the straight-thread ply that is produced during the butt-joining step (b) and then inserted into the cutter during the cutting step (c) is equal to or greater than 50% of the cutter inlet width, whereas the widest frontal width of the straight-thread strips that are butt-joined to make said straight-thread ply is less than or equal to 50% of said cutter inlet width.

2. The method according to claim 1 , wherein, during the preparation step (a), a calender is supplied by one or more reinforcing-thread reels that contain as many separate reinforcing threads as necessary to cover a desired frontal width of a straight-thread strip, in that the length of each reinforcing thread initially stored on said reinforcing-thread reel or reels, known as the “nominal storage length”, is identical, with a predetermined tolerance less than or equal to 20%, from one reinforcing thread to another, and in that, during a calendering operation, a continuous straight-thread strip known as a “rough straight-thread strip”, which has the desired frontal width and a length known as the “rough length”, which is equal to at least 80% of the nominal storage length is produced on said calender, from said reinforcing threads, and then said rough straight-thread strip is distributed to a plurality of separate reels of straight-thread strips that are then used jointly during the butt-joining step (b).

3. The method according to claim 2 , wherein, during the preparation step (a), each of the separate reels receives a portion of the rough straight-thread strip with a length of between 5% and 50% of the rough length.

4. The method according to claim 2 , wherein the nominal storage length of each reinforcing thread stored on the reinforcing-thread reel(s) used by the calender is between 200 m and 70 000 m.

5. The method according to claim 1 , wherein each straight-thread strip used has a frontal width of between 5% and 20% of the cutter inlet width.

6. The method according to claim 1 , wherein the straight-thread strips each have a frontal width of between 30 mm and 700 mm.

7. The method according to claim 1 , wherein the cutter inlet width is between 300 mm and 2000 mm.

8. The method according to claim 1 , wherein each reel of the plurality of separate reels that are prepared during the preparation step (a) and that is then used jointly with the other reels during the butt-joining step (b), contains a continuous straight-thread strip, the length of which is between 200 m and 30 000 m.

9. The method according to claim 1 , wherein the total surface area of the webs to be produced, known as the useful web surface area, is generated, during the preparation step (a), by one and the same operation of calendering a rough straight-thread strip, a developed surface area of which is between 100% and 120% of said useful web surface area, and in that said rough straight-thread strip is distributed substantially equally to a predetermined number of separate reels that each receive a corresponding fraction of the developed surface area of said rough straight-thread strip, and then all of said reels are used jointly during the butt-joining step (b).

10. The method according to claim 1 , wherein the cutting direction forms a cutting angle with respect to the common longitudinal direction of the straight-thread ply, and in that, during the initialization of the butt-joining step (b), the straight-thread strips coming from the separate reels are presented in a stepped manner by longitudinally offsetting respective fronts of said straight-thread strips with respect to one another at a longitudinal offset that depends on the value of the cutting angle.

11. The method according to claim 1 , wherein, during the butt-joining step (b), the straight-thread strips are disposed in parallel in pairs, such that said straight-thread strips have respective selvedges facing one another and such that said selvedges are spaced apart from one another and delimit, between one another, a gap known as the “join gap” of predetermined width, and in that said straight-thread strips are butt-joined by injecting into the join gap a malleable filling material of rubber or glue which bonds the selvedge of one of the straight-thread strips to the selvedge of the other straight-thread strip.

12. The method according to claim 11 , wherein, during the preparation step (a) or during the butt-joining step (b), at least one selvedge of said straight-thread strip or, respectively, said straight-thread strips intended to be bonded by the filling material is trimmed by making said straight-thread strip or, respectively, said straight-thread strips run in contact with a knife that bears in a sliding manner against the reinforcing thread that is closest to the selvedge in question, such that the relative movement of the straight-thread strips with respect to the knife makes it possible to eliminate, before butt-joining, any residual width of rubber that covers the reinforcing thread, specifically in order to expose the reinforcing thread along the length of the selvedge in question, such that a lateral limit of said reinforcing thread delimits the join gap that receives the filling material.

13. The method according to claim 12 , wherein at least one of the straight-thread strips contain metallic reinforcing threads, such that, during the preparation step (a) or during the butt-joining step, at least one selvedge of said straight-thread strip or, respectively, said straight-thread strips intended to be bonded by the filling material is trimmed by making said straight-thread strip or, respectively, said straight-thread strips run in contact with the knife that bears in a sliding manner against the metallic reinforcing thread that is closest to the selvedge in question, such that the relative movement of the straight-thread strips with respect to the knife

Assignees

• Michelin & Cie

Inventors

• Lhospitalier Jean-Francois

Classifications

• B29C65/54

  between pre-assembled parts · CPC title

• B29C66/435

  Making large sheets by joining smaller ones or strips together · CPC title

• B29D2030/381

  the inserts incorporating reinforcing parallel cords; manufacture thereof · CPC title

• B29C43/24

  Calendering · CPC title

• B29D2030/422

  Butt joining · CPC title