CA1121706A - Method and apparatus for manufacturing a pneumatic tire - Google Patents

Abstract

ABSTRACT

A method of preparing blanks for radial-ply tires having a predetermined bead core diameter comprising the steps of: extru-sion coating individual, elongated, reinforcing members aligned in a tubular array with a vulcanizable rubber composition; longitudi-nally moving the coated members aligned in a tubular array in a common direction while circumferentially spaced about an axis ex-tending in the direction; interconnecting the moving members by circumferentially extending deformable connecting means, thereby forming a tube about the axis, the tube having a diameter sustant-ially equal to the bead core diameter; severing the tube into axially consecutive sections; mounting the tube sections on a build-ing drum; incorporating bead rings into the axial terminal portions of the sections; radially expanding the axially central portion of each section while substantially maintaining the diameter of the axially terminal portions of each section, so as to form a toroid-ally shaped tire blank; and the deformable connecting means in the axially central portion being circumferentially deformed during the step of radially expanding so that the circumferential distance of the reinforcing members is increased in the axially central position.

Description

h~2i.7~6 .. . ...... _ _ . . . _ . . ............ . . . ... . .

Method of ~lanufacturing a Pneum;ltic Tire The invent~on relates to a method of manufacturing a pneumatic -tire where, in a first series of operations a tubeless inner plate may, if applieable, be laid on a carcass drum, then a strength bearing fabric is applied to the drum or over the tubeless inner plate where applicable, then the ~trength bearing unit is hammered radi~lly inwards at the axial ends of the carcass drum, then the bead cables are applied to the radially inward pointing segments of -the streangth bearing fabric, then the radially inward edges of the radially inward pointing ~egments of the strength bearing fabric are bent back over the bead cables again radially outwards and are laid o~f on the cylindrical part of the strength bearing fabr~c, then, oYer the thus laid doY~ edges of the strength bearing fabric~ and, where applicable, on the cylindrical segment of the strength bearing fabric, side wall strips~ andv where applica~le, bead reinforcements and Y-strips~ are applied, and where, in a second series o~ operations, on a tread drum (or build-up drum) at least two belts are laid and a tread is laid on top of these two belts, and where, further~ the initial product from the first series o~ operations, i~e, the carcass, i~ transferred from the carcass drum to a cambering drum, and the initial product resulting from the second series of operationst i~e.
the tread pack, is laid on the cambering drum over the axially cen-tral portion of the carcass, and where~ then, by axial retraction of the aambering drum, the carcass is shaped into a t~ru~ and at -the same time is brought into contact against the internal peripheral surface of the trea~n~ pack, and then the rubber mixture of the side wall strips and~ f the tread are overlapped and joined, and ~inally the blank thus produced is removed from the cambering drum and delivered to a ~ulcanizing press.

t70~

In known me~hods of this kind the strength bearing fabric is produced as a flat piece of fabric and is wound around the car-cass drum, or around the tubeless inner plate already present thereonO This results in an overlapping, and hence a poor le~el of unifoxmity in the tire produced therefrom.
The task of the invention is to eliminate the deficiencies of uniformity owning to the design of the stren~thbearing unit. To solve this problem it is proposed, according to the invention, to lay the strength bearing fabric on the carcass drum in tubular form~
The basic idea of preparing the strength bearing fabric in the form of a hose fabric also creates the conditions for simpli-fying the production flow and thereby reducing production costs.
That is to say, one may proceed as follows:
The tubular strength bearing fabric can be produced in a production line coordinated to the carcass drum. The basic strength bearing fabric hose emerging from this production line is immedi-ately drawn, as it com~s from the production line, over the car-cassing drum, and is then cut to the proper length.
In the production line one may start with the threads from which the strength bearing fabric is produced, coating these with rubber mixture in a multiple extruder, and then weaving the threads thus coated into a hose in a circular loom. it is important here for the strength imparting threads to run in the longitudinal direction of the hose and thus ultimately lie in the longitudinal direction on the carcass drum.
The term "threads" used herein applies either to textile threads or to steel cords, as used in full steel tire production ~or the strength bearing fabric. The textile threads may be of an

-2-7(~

elastomeric composition or may be made rom cotton threads spun from short fiber material.

-2a-The rubber mixture used to coat the threads is still suf-ficiently plastic in the finished s-trength bearing fabric hose so that the bead cables can be made to adhere by simply apply;ng pressure.

In the kno~n procedure described above it is customary to extrude or calender the semi-finished .items m~de of rubber mixture, i.e. the side wall strips, tread and, where applicable, the bead reinforcements, V-strips and liner strips, in -their final profiled form, and, a~ter cutting them into correct lengths, to bring them in~o position on the carcass drum or tread drum~ In explanation of the YarioUs terms here, bead reinforcements are strips incorpora-ted in the vicinity of the bead cable in order to reinforce -the bea.d zone; they are used particularly in heavy truck tires. V-strips are ones applied either on the carcass drum in the region intended for subsequent installation on the in5ide of the tread pack~ or on the cambering drum on the already toroidally shaped carcass~ in order to fill up the V-shaped voids between the toroidally shaped carcass and the tread pack. Liner strips are ones which are applied on the carcass drum to -the strength hearing fabric in the region intended for subsequent installation on the inner side of -the tread pack, i.n order to provide a padding between the tread pack and the carcass.

The known manner of producing the semi ~inished items complicates the manufacture of the tire because e~en when the rubber mixture remains constant uneven shrinkage of different parts of strips must be expected, so that when these strips are applied, ad-justment has to be undertaken by hand, so that automation of the manufacture of tires is rendered difficult or impossible. A further purpose of the inventionJ there~ore~ is to bring up the semi-finished items in such a way as to reduce to a minimum or -to eliminate com-pletely the hand-adjustment operations that have hitherto been re-quired, To solve this task i.t is further proposed, according to the inven~ion, that the side wall strips, and~ where applicable 7 also the bead reinforcements and V-strips are applied by coiling '7~
l~

an extrusion strip extruded in the i~lmediate vicinity of the carcass drumin several turns situated side by side and, where applicable, one abo~e the otherj where the carcass drum rotates. Similarly, it i5 also proposed that the tread strip be prepared from an ex trusion strip extruded in the immediate vicinity of the tread drum, by laying this extrusion strip side by side in several turns and, here applicable, one above the other.

The invented manner of presenting the semi-finished items makes it necessary to profile these semi~finished items on the car-cass drum and on the tread drum. For this profiling operation it is proposed that the side wall strips and, where applicable, the bead reinforcements and Y-strips~ after being coiled on their various ex-trusion strip reels should be profiled by means of at least one profiling roll controlled biaxiallyy i.e. controlled in its motion both in the axial direction of the carcass drum and in the radial direction of the feed to the carcass drum, the axial width of said profiling roll being less than the axial width of the finished s;de wall strip, bead reinforcement or V strip as -the case may be, The same applies to the tread, i.e. it is further pro~
posed that the tread should be profiled by means of a profiling roll controlled biaxially, i.e. controlled in its motion both in axial direction of the tread drum and in the radial feed directionO

Taken together, the measures proposed by ~he invention make it possible for the first t,iT.~e to ack.iev~ a rul.]y ~?r!rn(l.lol~
-tire production flow and hence to permit automated production con-trol.

The accompanying figures explain the invention schemati-cally~
Fig. 1 shows a carcass drum arrangement with a device -for the introduction of a bead cable in readiness~

Fig. la shows the carcass drum with a device for applying a tubeless inner platel Fig. lb shows the carcass drum arrangement with a production line for the production o~ a strength bearing fabric hose and its application;

Fig. lc sho~s the carcass drum arrangement with devices for raclially hammering in the ends of the ~trength bearing fabric hose:

Fig. ld shows the carcass drum arrangements wlth devices for applying the bead cables:

Fig~ le shows the carcass drum arrangement with devices for bending back the radial inner ends of the strength bearing fabric hose around the bead cables~

Fig. lf shows the carcass drum arrangement with extruders for extruding on the extruded strips constituting the side wall strips and with profiling rolls for profiling the side ~all strips~

Fig. lg shows the carcass drum arr~ngement with with a transfer arrangement for transferring the finished carcass to a cambering drum;

Fig. 2 shows a tread drum with delivery mechanisms for -the feeding of belts~

Fig. 2a and b show the carcass drum wi-th an extruder for extruding on the tread material over the belts in two different views;

Fig. 2c shows a profiling apparatus for profiling the tread material on the tread drums Fig. 2d shows a plan view of the belt pack partially cut away Fîg. 3 shows an assembling machine comprising a cambering drum, a tread drum and transferring rlng~

Fig. 3a ~s a partial view of the assembling machine with the cambering drum and a carcass partially shaped into a torus~

Fig. 3b shows a profiling apparatus on the camberirlg drum for joining the tread and the side wall strips3 Fig. 4 shows an apparatus for produc;ng the belt material, In Fig. I the number 10 denotes a bearing frame on which a carcass drum 12 is mounted rotatably with the aid of a rotary drive mechanism~ On bearing frame 10 a cable setting device 14 is provided which is in the process of receiving a cable 16 fro~ a cable feed mechanism 18. In Fig. la cable 16 has already been transferred to the cable setting apparatus 14 and is held in readiness there.
A feed drum 20 for the feeding of tubeless inner plate material is also recogni~able in Fig. la. This material 22 is wound onto the radially expanded carcass drum 12 as the latter rotates and is cut off at the end of one full turna Concerning Fig. 1 it should be added that there the carcass drum is radially contracted so as to permit its being overrun by means of the cable feeding device, In Fig, lb the radially expanded carcass drum 12 with tubeless inner plate 22 can again be recogni~ecl. Over tubeless inner plate 22~ the advance end 24 of a strength-bearing fabric hose 26 is drawn, Hose 26 is produced in a production line 28, Produc-tion line 28 comprises a spool rack 30 with a multiplicity of spools of tnread 32. From spools 32 threads 3~ pass through a multiple extrusion apparatus 3~ by which the threads have a plastic mixture of rubber sprayed onto them. The coated threads 38 pass through`
a circular loom 40 in which a fabric hose 26 is woven from them, The latter contains coated threads 38 running in the longitudinal direction. It also contains threads running in the peripheral direction which, during the subsequent cambering of -the caricass on the carcass drum according to Fig. 3a are either elastically ex-tensible in such a way that they can follow the camber, or are de-g~7r~

signed -to be weak enough so as to blfak during the cambering opera-tion. The forward end of hose 26, drawn onto carcass drum 12, is cut off by a severing device 42 in such a way that an edge of the strQngth bearing fabric hose, denoted in Fig. lb by 44~ overhang~
the carcass drum in both axial directions by approxima~ely the same amount.

In Fig. lc~ at carcass drum 12, a folding apparatus can be recognized, comprising two folding rolls 46, 48 which have just folded the oYerhanghg edges 50, 52 of hose section 44 radially inwards and have laid them agains-t the end faces of carcass drum 12. The plasticity of the thread coatings in the fabric hose ensures that the edges thus folded radially inwards retain -this position for the time being.

In Fig. ld, by means of two cable setting devices, i.e.
device 14 already introduced and another cable setting device ~4~
the bead cables, i.e. the already mentioned bead cable l6 and the oppositely situated bead cable 56, are put in pLace. Cable setting device 54 is not fixedly incorporated wi-th drum arrangement 10, but is movable relative -thereto perpendicularly to the axis of the drum in the direc-tion of arrow X, so that this cable setting arrangement with the bead cable ~6 already retained thereon can be brought into alignment with carcass drum 12. Bead cables 16 and 56 are simply pressed onto -the folded sections 50 and 52 of the fabric hose and are retained there owing to the plastici-ty of the rubber compound covering the fabric threads.

Fig. le shows how the radially innermost sections of the rad~ally inwards-folded edges of hos~ 50, 52 are bent back and radially outwards and laid against the perimeter of the drum. This is ac-complished by means of pneumatically inflatable rubber bellows ac commodated inside carcass drum 12 and which are deformed in ~he manner shown in Fig. le when inflated.

The par-ticulars of this -type of folding apparatus are essentially known, ~2~ 0~

In Figure lf the carcass drum arrangement 10 with carcass drum 12 is again recognizable. Two extruders 62, 64 have now been brought up into operating position opposite the carcass drum.
These extruder each extrude a strip 66 or 68, as the case may be, onto carcass drum 12 as the latter turns, so that extruded strips 66, 68 are wound onto the carcass drum, forming side wall strips 70, 72; this results from lateral movement of extruders 62, 64 side by side, and, if applicable, one above the other. Treads sic 70, 72 extend out over the axially inwards-pointing ends of the folded fabric hose edges and beyond.
In Figure lf, profiling rolls 74, 76 are represented, which are intended to impart to side wall strips 70, 72, at first applied in rough form, the desired profile. Profiling rolls 74, 76 are controlled in their lateral advancing and radial feeding motions. After profiling side wall strips 70, 72, the carcass, if bead reinforcements and/or V strips have not yet been applied, is completed. If bead reinforcements or bead strips are applied, this is done in the same manner, i.e. with the aid o~ special extruders and with the aid of suitable proEiling rolls.
In Figure lg a transfer device 71 has been brought into the ready position relative to carca~s drum 12. This transfer apparatus 78 comprises two grappling arms 80 with claws mounted thereon. Claws 82 move in radial direction and engage in the radially inward edges of the carcass, i.e. underneath the bead.
As soon as claws 82 have engaged the beads, carcass drum 12 is contracted from the radially expanded position according to Figure ld into the radially contracted posi~ion according to Figure lh, so that~ as represented in Figure lh, the completed carcass can now be removed from the carcass drum.
In Figure 2a - 2c, production of the tread is explained.
In Figure 2 a tread drum 84 will be recognizedO Onto this tread drum two belts 90; 92 are wound, coming from two feed mechanisms 86, 88. The belts are made of steel cord fabric coated with rubber compound. One layer is wound onto tread drum 84 from each belt 90, 92.

In Figure 2a and 2b we recognize how an extruder 94 applies an extruded strip 96 over the belt. Extruder 94 is again laterally movable sio that on rotation of the tread drum side-by-side turns of the extruded strip are wouncl and produce the tread strip. The tread strip is denoted by 98. The combination of the two belts 90 and 92 and tread strip 98 isi called the tread pack.
Figure 2d shows, in cut-away, the two belts 90 and 92 and tread strip 98, i.e., in combination, tread pack 100.
For the profiling, a profiling roll 102 is shown in Figure 2c which is movable in the axial direction of tread drum 84 and is adjustable radially thereto, axial and radial motions being controlled relative to each other by a program. In the operational step represented in Figure 2c the tread pack is comple~ed and is now combined with the carcass, a]so completed, to form a tire blank. This combining takes place in the assembling machine according to Figure 3.
In Figure 3 one may again recognize the complete carcass which has been transferred by transferring apparatus 78 to a cambering drum 104. Tread drum 84 can also be recognized with the completed tread pack 100. Between cambering drum 104 and tread drum 84 there is another transferring apparatus 106 which is designed 50 that it travels axially past tread drum 84 and can seize the finished tread pack, Eor example by means of suction apparatus. Transferring apparatus 106 brings the completed tread pack over cambering drum 104 in the position shown in Figure 3a.
Cambering drum 104 is designed so that it can grasp the beads of the carcass so as to pull these beads together for pur-poses of cambering the carcass. By comparing Figure 3 and 3a, it will be recognized that the two halves of the cambering drum, which in Figure 3 were a distance apart corresponding to the extended carcass, have moved together in Figure 3a while the carcass is being cambered~ Owing to the cambering of the carcass, the outer perimeter of the cambered carcass has come lnto contact, in Figure 3a, wlth the insiide surface of tread pack 100. In the V-shaped spaces 108 between tread pack 100 and the carcass, V-strips can be inserted, which can be done either on carcass drum 12 or on the cambering drum before tread pack g _ ~.~2~

100 is brought over i-t.

Fig. 3b shows how, after camberino, the rubber compound of tread pack 100 and side wall strips 70 are joined together by means of a profiling roll 110 so that the completed -tire blank is formed. This tire blank can now be introduced in a known manner into the vulcanizing press.

According to Fig. 2d the tread pack includes two belts 90 and 92, which can be produced separately in a traditional manner.
The invention also e~braces a novel production of the belts in co-herent form, and indeed production in a single opera-tion. For more detailed illustration, refer to Fig. 40 In Fig. 4 one recognizes a spool frame 110 from which strands of steel cord 112 are drawn.
Strands 112 are coated with a plastic rubber compound in a multiple extrusion head 114 fed from a multiple extruder 116~ so that a hose comprising separate strands of steel cord~c5ated with compound emerges from multiple extrusion nozzle 114. The ~ is denoted in Fig. 4 by 118. Hose 118 passes be-tween a pair of crushingr rollers 1203 after which it is wound onto a reel 122. Crushing rollers L20 and reel 122 are mounted on a rotor 124 which is rotatable about an axis R and is powered. As a result of -the rotary motion of rot~r 124, hose 118 is already twisted before it enters between the pair of crushing rollers 120~ When the hose is flattened between rollers 120, the individual steel cord strands 112 thus make acute a~gles with the direction of travel, and indeed the strands in the layers formed by the flattening of the hose appear as represented in Fig. 25 the strands of the two layers cohering, of course, at the edges of the flattened two-layer structure, It has been found that the use of such a coherent double belt is acl~antageous compared with the use of separate belts in ac-cordance with Fig. 2d. This is true particularly because the danger of belt edge detachment is thereby reduced.

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of preparing blanks for radial-ply tires having a predetermined bead core diameter comprising the steps of:

(a) extrusion coating individual, elongated, reinforcing members aligned in a tubular array with a vulcanizable rubber composition;

(b) longitudinally moving the coated members aligned in a tubular array in a common direction while circumferentially spaced about an axis extending in said direction;

(c) interconnecting the moving members by circum-ferentially extending deformable connecting means, thereby forming a tube about said axis, said tube having a diameter substantially equal to said bead core diameter;

(d) severing said tube into axially consecutive sections;

(e) mounting the tube sections on a building drum;

(f) incorporating bead rings into the axial terminal portions of said sections; and (g) radially expanding the axially central portion of each section while substantially maintaining the diameter of the axially terminal portions of each section, so as to form a toroidally shaped tire blank;

(h) said deformable connecting means in said axially central portion being circumferentially deformed during said step of radially expanding so that the circumferential distance of said reinforcing members is increased in said axially central portion.

2. Apparatus for preparing blanks for radial-ply tires having a predetermined bead core diameter comprising:

(a) extruding means including a plurality of nozzles for separately extruding from each nozzle a strand of vulcanizable rubber composition, said nozzles being arranged to extrude a plurality of said strands in a tubular array in a common direction and circumferentially spaced about an axis extending in said direction;

(b) feeding means for feeding a plurality of elongated reinforcing members to said nozzles respectively for discharge from said nozzles of respective reinforcing members individually coated with said composition;

(c) textile machinery means for receiving the coated reinforcing members in said tubular array from said extruding means and for interconnecting said members into a continuous elongated tubular structure having a longitudinal axis and a diameter substantially equal to said bead core diameter, said reinforcing members being elongated parallel to said longitudinal axis, said textile machinery means including means for applying circumferentially extending deformable connecting strands about said coated reinforcing members thereby to form said tubular structure;

(d) severing means for axially severing a plurality of sections of said structure from each other;

(e) means for mounting sections of said structure on a building drum;

(f) means for incorporating bead rings into axially terminal portions of said sections;

(g) shaping means for radially expanding the axially central portion of each section while substantially maintaining the diameter of the axially terminal portions of each section so as to form therefrom a toroidally shaped tire blank;

(h) said shaping means operating to circumferentially deform said deformable connecting means in said axially central portion during said step of radially expanding so that the circumferential distance of said reinforcing members is increased in said axially central portion.

3. The method according to Claim 1 wherein said circumferenti-ally extending deformable connecting means comprise thread members wound circumferentially about said reinforcing members.

4. The method according to Claim 3 wherein said thread members comprise elastically deformable members.

5. The method according to Claim 4 wherein said elastically deformable members are formed of an elastomeric composition.

6. The method according to Claim 3 wherein said thread members comprise breakable cotton threads spun from a short fiber material.

7. The method according to Claim 3 wherein said threads are ruptured during said step of radially expanding.