Method for producing a pneumatic vehicle tire

Abstract

A method for making a vehicle tire wherein the vehicle tire includes a belt having at least one belt layer made of parallel steel cords embedded in rubber. The belt ply is built up on a building drum in order to produce a tire blank. Upon completion of the tire blank, the tire blank is shaped and vulcanized in a vulcanizing press. The method includes applying the belt ply made of parallel, extensible steel cords embedded in rubber to a building drum to build up the belt. After the tire blank is completed, the tire blank is shaped and vulcanized in a vulcanizing press to reduce the extensibility of the steel cords.

Claims

1. A method for making a vehicle tire for a utility vehicle, the vehicle tire including a carcass, a belt defining a circumferential direction U and being built up radially outside the carcass, and a profiled tread built up on the belt, the belt being made of a plurality of belt plies arranged lying one on top the other from a radially inner ply to a radially outer ply, the radially inner ply being a radially inner working ply and the radially outer ply being a radially outer working ply, the radially inner and radially outer working plies being belt plies having mutually parallel reinforcement steel cords having a pregiven elasticity embedded in rubber, the reinforcement steel cords of the radially inner working ply having an angle () in the range of 1024 to the circumferential direction U, the reinforcement steel cords of the radially outer working ply having an angle () in the range of 1024 to the circumferential direction U, the reinforcement steel cords of the radially inner working ply and the radially outer working ply having respective inclinations with respect to the circumferential direction U which are opposite to each other; the method comprising the steps of: applying the inner working ply and the outer working ply as open steel cords embedded in rubber to a building drum for building up the belt so that the belt becomes comprised of the radially inner ply as the radially innermost belt ply, an intermediate belt ply, and the radially outer working ply as the radially outermost belt ply and thereafter completing a tire blank which is an uncured assembly of the carcass, the belt, and the tread; and, after completion of the tire blank, shaping and vulcanizing the tire blank in a vulcanizing press while, at the same time, reducing the extensibility of the steel cords and closing the steel cords to form closed steel cords, wherein the open steel cord is of the type 3+80.35 LL 9/18 mm with a break load of F=3100 N and with an elongation D of D=0.24% at 10% of the breaking load.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described with reference to the drawings wherein:

(2) FIG. 1 shows the cross-sectional view of a pneumatic vehicle tire of radial construction for commercial vehicles;

(3) FIG. 2 shows a plan view of the belt of FIG. 1 in accordance with section II-II of FIG. 1, in which all the other components of the tire are not shown for the sake of simplicity;

(4) FIG. 3 shows a partial cross-sectional view of a pneumatic vehicle tire similar to the view of FIG. 1 with an alternative belt design;

(5) FIG. 4 shows a plan view of the belt of FIG. 3 in accordance with section IV-IV of FIG. 3, in which all the other components of the tire are not shown for the sake of simplicity;

(6) FIG. 5 shows a partial cross-sectional view of a pneumatic vehicle tire similar to the view of FIG. 1 with another alternative configuration of the belt;

(7) FIG. 6 shows a plan view of the belt in FIG. 5 in accordance with section VI-VI of FIG. 5, in which all the other components of the tire are not shown for the sake of simplicity; and,

(8) FIGS. 7A to 7D show a schematic view intended to show the production of the pneumatic vehicle tire in FIGS. 7A to 7D, which represent different method steps.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

(9) FIGS. 1 and 2 show a pneumatic vehicle tire of radial construction for commercial vehicles, having two side walls 2 extending in the radial direction R of the vehicle tire and a crown region 3 formed axially between said walls. The side walls are each formed, at the end of the extension thereof which points inward in the radial direction, with a bead region 1, in which a bead core 4 resistant to tension in the circumferential direction U and extending over the circumference of the tire in the circumferential direction is formed. The bead cores 4 are formed by wound wire embedded in rubber extending in the circumferential direction U of the pneumatic vehicle tire. An apex (bead filler) 6 of triangular cross section and of hard rubber material is formed in a conventional manner on the bead cores 4. The pneumatic vehicle tire is formed with a carcass 5, which, starting from the bead core 4 formed in the left-hand bead region 1 of the pneumatic vehicle tire, extends outward in the radial direction R of the pneumatic vehicle tire, through the left-hand side wall 2, to the crown region 3 and, in the crown region 3, extends in the axial direction A of the pneumatic vehicle tire to the right-hand side wall 2 and, in the right-hand side wall 2 of the pneumatic vehicle tire, extends radially inward to the bead core 4 formed in the bead region 1 of the right-hand side wall 2. In both bead regions 1, the carcass is formed so as to extend in each case along the axial inside of the bead core 4 to the radial inside of the respective bead core 4, then, as an extension, in the axial direction along the radial inside of the bead core 4 to the axial outside of the bead core 4 and then, as an extension, radially outward on the axial outside of the bead core 4 as a turned-up part 7. The turned-up part 7 of the carcass 5 extends along the axial outside of the apex 6 and ends on the axial outside of apex 7. The carcass 5 is formed by a carcass ply extending over the entire circumference of the pneumatic vehicle tire in the circumferential direction U and including parallel cordsfor example steel cordsembedded in rubber which extend substantially in the radial direction R in the region of the side walls 2 and substantially in the axial direction A in the crown region. An inner layer 12 of a rubber material that is particularly impermeable to air extends from the left-hand bead region 1 to the right-hand bead region 1 on the side of the carcass 5 which faces the inside of the tire. An additional bead reinforcing strip 8, which extends over the entire circumference of the pneumatic vehicle tire, is in each case formed in the bead region 1 on the side of the carcass 5 which faces away from the bead core 4. The bead reinforcing strip 8 is, for example, a strip of material consisting of parallel reinforcements of textile or metal construction embedded in rubber.

(10) In the region of the tire crown 3, a belt 9 extending over the entire circumference of the pneumatic vehicle tire in the circumferential direction U and from the left-hand tire shoulder to the right-hand tire shoulder in the axial direction A is formed on the carcass 5 to the outside of the carcass 5 in the radial direction R of the pneumatic vehicle tire, the belt being formed by three belt plies 13, 14 and 15 arranged one above the other and one on top of the other in the radial direction R. A profiled tread 10 extending over the entire circumference of the pneumatic vehicle tire in the circumferential direction U and from the left-hand tire shoulder to the right-hand tire shoulder in the axial direction A is formed on the belt 9, radially to the outside of the belt 9, the tread completely covering the belt 9. A rubber side wall strip 11 is formed in the region of the tire side walls 2, on the side of the carcass 5 which faces axially away from the tire, said strip extending in the radial direction R from the bead region 1 to the profiled tread 10 in the crown region 3.

(11) The radially inner belt ply 13 and the radially outer belt ply 15 are designed as working plies of the tire and each extend in the circumferential direction U over the entire circumference of the pneumatic vehicle tire and from the left-hand tire shoulder to the right-hand tire shoulder in the axial direction A. Working ply 13 is formed by a layer of parallel reinforcements 23 in the form of filaments embedded in rubber which extend substantially in a straight line over the entire width (a), measured in the axial direction A, of belt ply 13 and enclose an angle of inclination of 1024 with the circumferential direction U. Working ply 15 is formed by a layer of parallel reinforcements 25 in the form of filaments embedded in rubber which extend substantially in a straight line over the entire axial width (c) of belt ply 15 and enclose an angle of inclination of 1024 with the circumferential direction U. The direction of inclination of the reinforcements 25 of working plies 15, when viewed in the circumferential direction U, is formed in the opposite axial direction A to the direction of inclination of the reinforcements 23 of working ply 13. The third belt ply 14 formed between the two working plies 15 and 13 extends over the entire circumference of the pneumatic vehicle tire in the circumferential direction U and from the left-hand tire shoulder to the right-hand tire shoulder in the axial direction and is designed as a 0 ply. For this purpose, belt ply 14 is formed by parallel reinforcements in the form of filaments embedded in rubber which extend in a straight line over the entire circumference of the pneumatic vehicle tire, enclosing an angle of 05 with the circumferential direction U, and are thus aligned substantially in the circumferential direction U of the pneumatic vehicle tire. All three belt plies 13, 14 and 15 extend on both axial sides into a position in the respective tire shoulder which is axially to the outside of the ground contact surface, indicated by the axial width T.sub.a of the ground contact surface. Belt ply 14 is in direct physical contact both with working ply 13 arranged underneath it and with working ply 15 arranged above it over its entire axial extent.

(12) The 0 ply 14 extends over an axial width (b) in the axial direction A, the lower working ply 13 extends over an axial width (a) in the axial direction A, and the upper working ply 15 extends over an axial width (c) in the axial direction A in the tire, where a>c>b. In this arrangement, the inner working ply 13 extends beyond the axial position of the respective belt edge of the 0 ply 14 by an axial length of extension (e) on both axial sides of the 0 ply 14. The outer working ply 15 likewise extends beyond the axial position of the respective belt edge of the 0 ply 14, in each case by an axial length of extension (d), in both axial directions. The lengths of extension (e) and (d) of this overlap are governed by e>d. Here, the dimension (d) is given by d10 mm. In the illustrative embodiment, the dimension (e) is given by e60 mm. The two working plies 13 and 15 do not touch one another, even in the region of the overlap.

(13) FIGS. 7A to 7D show the production of belt plies on a belt building drum 28 in a schematic sequence in FIGS. 7A and 7B, while FIG. 7C shows the combination of the fully built belt assembly 33made of the various belt plies built up one on top of the other and the treadwith the toroidal carcass packet 32 produced independently thereof on a carcass building drum 30made of the various carcass plies, the bead cores, the tire inner layer and the side partsto give the tire blank 31, and FIG. 7D shows the final shaping and vulcanizing in a tire vulcanizing press 34.

(14) FIGS. 7A and 7B show the production of the belt plies in the belt assembly 33 using belt ply 23 by way of example. For this purpose, a belt ply building material 13 produced in the form of a strip comprising parallel steel cords 23 embedded in the rubber and used to produce working ply 13 is fed continuously to a belt building drum 28, which is formed with a radially outer cylindrical or contoured building surface 29, concentrically with the axis of rotation of the belt building drum 28. During this process, the belt building drum 28 is driven in rotation about the axis of rotation thereof. As it does so, the belt ply building material 13 in strip form is pulled around the radially outer building surface 29 of the belt building drum 28 until it completely surrounds the circumference of the building surface 29. This state is illustrated in FIG. 7B. Following this, a belt ply building material 14 in strip form for producing belt ply 14 and including the parallel reinforcements 24 formed therein is likewise built upin a manner not shownon belt ply 13, which has already been built up, by rotating the belt building drum 28. In a similar waynot showna belt ply building material 15 produced in strip form and including the parallel reinforcements 25 embedded therein in the rubber is then built up around the belt building ply 14 formed in this way in order to produce working ply 15. Following this, a rubber tread material in strip form is then built up around the outer working ply 15 in order to produce the tread 10.

(15) The reinforcements 23 of the belt ply building material 13 in strip form for building up working ply 13 and the reinforcements 25 of the belt ply building material 15 in strip form for building up working ply 15 are open steel cords which have a breaking load F of F>2500 N when subjected to a tensile load and have an elongation D of D 0.2% at 10% of the breaking load. Open steel cords are steel cords in which the filaments of the steel cord do not have any direct contact with one another in the steel cord. Steel cords of this kind are open steel cords of the type 3+80.35 LL 9/18 mm with a breaking load F=3100 N and with an elongation D of D=0.24% at 10% of the breaking load, for example.

(16) A carcass packet 32 is produced in a conventional manner on a carcass building drum 30. For this purpose, the rubber material in strip form for producing the airtight inner layer of the tire is built up first on the radially outer surfaces of the carcass building drum 30, for example, followed by the carcass plies and, on the carcass plies, the bead cores with apex. To produce the toroidal shape, the bead cores are then moved toward one another in the axial direction of the carcass building drum 30, and the plies formed by the carcass plies and the inner layer are then expanded radially between the bead cores, and the carcass ply sections formed axially outside of the bead cores are folded up to form carcass turnups on the outside along the bead core and the apex. In addition, the rubber assembly strips forming the tire side walls are applied to the carcass plies. The carcass packet 32 is joined to the belt assembly 33 formed on the belt building drum 28 to give a tire blank 31. For this purpose, the belt assembly 33 is pushed onto the carcass packet 32 concentrically with the carcass packet 32, and joined to the latter. This state is shown in FIG. 7C.

(17) The tire blank 31 produced in this way then undergoes shaping and vulcanizing in a tire vulcanizing press 34. For this purpose, the tire blank 31 is inserted into the tire vulcanizing press 34 formed by the two side shells 35 that perform final shaping on the tire side parts and by the tread molding segments 36 acting radially from the outside. The side shells 35 are moved axially into the target position thereof for final shaping of the tire side wall, and the tread molding segments 36 acting radially from the outside are moved into the target position thereof in the radial direction of the tire blank 31 for final shaping of the tread profile. The tire blank 31 is then raised slightly more from the inside, in the radial direction of the tire blank with the aid of hot steam and, if appropriate, with the aid of a heating bellows, thereby implementing the residual elevation, and, during this process, is pressed into the tread molding segments 36 in order to impart the final shape to the tread profile. During this residual elevation and under the action of heat and pressure, the steel cords 23 of working plies 13 and the steel cords 25 of working plies 15 are extended and, in the process, the cord structure thereof is closed, the cord type thereof being modified at the same time. During this process, the tire blank 31 is vulcanized under the action of pressure and temperature into the pneumatic vehicle tire. After the modification to the structure, the steel cords 23 and 25 are closed and, when subjected to a tensile load, have a breaking load F of F=3100 N and an elongation D of D0.2%, e.g. D=0.18%, measured in the tire, at 10% of the breaking load. A closed steel cord is a steel cord in which the outer and inner filaments are in point or linear contact with one another.

(18) In another, alternative embodiment (not shown), the steel cords 23 and 25 used in the building plies 13 and 15 are steel cords of modifiable length of twist with a twist that can be modified by tension having a first length of twist. The first length of twist of the steel cords is designed to be a maximum of 10 mm.

(19) During the residual elevation and vulcanizing in the vulcanizing press, the length of twist of these steel cords is increased owing to the tensile forces that are acting, and they then have a second length of twist higher than the first length of twist. The values are determined by means of the BISFA E6 standard test method for steel cords.

(20) In one embodiment, the reinforcements 24 are steel cords. In another embodiment, the reinforcements 24 are steel cords which are configured as high-elongation cords (HE cords).

(21) High-elongation cords of this kind have an elastic modulus which is lower at an elongation of between 0% and 2% than the elastic modulus thereof at an elongation of more than 2%.

(22) In one illustrative embodiment, =1, =20, =20, d=11 mm and e=15 mm are chosen.

(23) In an alternative embodiment (not shown) of the abovementioned embodiments, the angle of inclination of the reinforcements 23 of the inner working ply 13 is in each case made larger than the angle of inclination of the reinforcements 25 of the outer working ply 15.

(24) In an alternative embodiment (not shown) of the abovementioned embodiments, the angle of inclination of the reinforcements 23 of the inner working ply 13 is in each case made smaller than the angle of inclination of the reinforcements 25 of the outer working ply 15.

(25) FIGS. 3 and 4 show another alternative embodiment of the pneumatic vehicle tire, in which the belt 9 is formed with an additional belt ply 16 on the radial outer side of the outer working ply 15, in addition to the belt plies 13, 14 and 15 illustrated in FIGS. 1 and 2, the additional belt ply 16 extending over the entire circumference of the pneumatic vehicle tire in the circumferential direction U and from the left-hand tire shoulder to the right-hand tire shoulder in the axial direction A of the pneumatic vehicle tire. Belt ply 16 is formed by a layer of parallel reinforcements 26 in filament form embedded in rubber, which extend substantially in a straight line over the entire axial width (f) of belt ply 16 and enclose an angle of inclination of 1545 with the circumferential direction U. Belt ply 16 extends in direct physical contact with working ply 15 over its entire axial extent and ends in an axial position between the closest belt ply edge of the 0 ply 14 and the closest belt ply edge of the radially outer working ply 15 at both of its belt ply edges in the axial direction A, leaving an axial spacing (g) from the belt ply edge of the 0 ply 14 of g<d. The width (f) is the measure of the axial extent of the additional belt ply 16, where b<f<c<a.

(26) In one illustrative embodiment, the reinforcements 26 of belt ply 16 are formed with the same angle of inclination as the reinforcements 25 of working ply 15.

(27) The reinforcements 26 are steel cords.

(28) In another embodiment (not shown), the additional belt ply 16 is designed as a 0 ply and the angle of inclination of the reinforcements 26 thereof, which extend over the entire circumference of the pneumatic vehicle tire, is 05. In forming the additional working ply 16 as a 0 ply, the reinforcements 26 are steel cords of known type in one embodiment. In another embodiment, the reinforcements 26 of the working ply 16 designed as a 0 ply are steel cords which are configured as high-elongation cords (HE cords). High-elongation cords of this kind have an elastic modulus which is lower at an elongation of between 0% and 2% than the elastic modulus thereof at an elongation of more than 2%.

(29) FIGS. 5 and 6 show another alternative illustrative embodiment of the pneumatic vehicle tire, in which, unlike in the illustrative embodiments shown in FIGS. 1 and 2 and described in relation to FIGS. 1 and 2, the belt 9 is additionally formed with a belt ply 17 arranged in a radial position between the radially inner working ply 13 and the carcass 5, the belt ply 17 extending over the entire circumference of the pneumatic vehicle tire in the circumferential direction U and from the left-hand tire shoulder to the right-hand tire shoulder in the axial direction A of the pneumatic vehicle tire. Belt ply 17 is formed by a layer of parallel reinforcements 27 in filament form embedded in rubber, which extend substantially in a straight line over the entire axial width (h) of belt ply 17 and enclose an angle of inclination of 4590, e.g. =50, with the circumferential direction U. Belt ply 17 extends in direct physical contact with working ply 13 over its entire axial extent and ends in an axial position between the closest belt ply edge of the 0 ply 14 and the closest belt ply edge of the radially outer working ply 15 at both of its belt ply edges in the axial direction A, leaving an axial spacing (k) from the belt ply edge of the 0 ply 14 of k<d<e. The width (h) is the measure of the axial extent of the additional belt ply 17, where b<h<c<a.

(30) In one illustrative embodiment, the reinforcements 27 of belt ply 17 are formed with the same direction of inclination as the reinforcements 23 of the radially inner working ply 13.

(31) The reinforcements 27 are steel cords.

(32) In other alternative embodiments (not shown), the additional inner belt ply 17 illustrated in connection with FIGS. 5 and 6 is also formed in the embodiments with an additional belt ply 16 which is illustrated in connection with FIGS. 3 and 4. In this case, the belt 9 is formed by a 5-ply arrangement with the belt plies 17, 13, 14, 15 and 16 arranged one above the other, radially from the inside outward.

(33) It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.

LIST OF REFERENCE SIGNS

(34) (Part of the description)

(35) 1 bead region

(36) 2 side wall

(37) 3 crown region

(38) 4 bead core

(39) 5 carcass

(40) 6 apex (bead filler)

(41) 7 carcass turnup

(42) 8 bead reinforcing strip

(43) 9 belt

(44) 10 profiled tread

(45) 11 rubber side wall strip

(46) 12 inner layer

(47) 13 belt ply (working ply)

(48) 14 belt ply (zero degree ply)

(49) 15 belt ply (working ply)

(50) 16 belt ply

(51) 17 belt ply

(52) 23 reinforcement

(53) 24 reinforcement

(54) 25 reinforcement

(55) 26 reinforcement

(56) 27 reinforcement

(57) 28 building drum

(58) 29 building surface

(59) 30 building drum

(60) 31 tire blank

(61) 32 carcass packet

(62) 33 belt assembly

(63) 34 vulcanizing press

(64) 35 side part

(65) 36 tread profiling segment