FI66312C - FOERFARANDE FOER FOERNYANDE AV SLITEN SLITYTA PAO LUFT- ELLER HELGUMMIYTTERRING - Google Patents

Description

R3C ^ n M rt «ANNOUNCEMENT Λ o J9a L» J v · 1) utlAggn i ngsskmpt OOOl ^ ^ ^ (SI) K * .lk! /Fcn.CL3 B 29 H 17/37 ENGLISH — FINLAND (21) 7917 * 0 (22) HriMmUplM— MwWfcmmrfm 31.05.79 (23) ΑΜαφβΝ · —Glklghäfsdag 05.10.76 (41) Translator J «tUMfcsl - MMt offantllg 3] g 5 η g

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Patent- oeh registerstyrelaen AmMcm latkfd oeh iicUkrlftM poMIcarad 29.06.8 * 4 (32) (33) (31) Pyydetty «ομιιμμ · —Bogirt pnortt * i o. 10.75 23.0 * 4.76 Federal Republic of Germany Förbunds-republiken Germany (DE) P 25 * 45 * 463.1 P 2617760.6 (71) Bandag Incorporated, Bandag center, Muscatine, Iowa 52761, USA (72) Wilhelm Schelkmann, Witten, Germany Federal Republic of Eastern Förbundsrepubliken Tyskland (DE) (7 **) Leitzinger Oy (5 * 0 Method for retreading a worn pneumatic or solid rubber tire - Förfarande för förnyande av sliten slityta pä luft-eller helgummiytterring (62) Avdelad frln ansökan 762832 (utläggningsskrift 66311)

The invention relates to a method for renewing the tread of a worn pneumatic or solid rubber tire, in which a binding rubber layer is placed on the pretreated carcass of the tire and on it a prefabricated rubber tread in the form of a ring with an inner diameter less than or equal to the outer diameter of the carcass. gaseous inclusions between or away from the overlapping layers and thus the prefabricated ring blank is heated in an autoclave to vulcanize the bonding layer.

In a known method (US 3,738,893), a tread tire is drawn on a circumferential and radially expandable support frame in which the ring is stretched in a polygonal shape. The ring is held coaxially with the carcass already treated and the support frame stretches the ring so that it can be transferred directly to the circumference of the carcass by means of the frame. This method requires the use of a relatively complex device.

It has also been proposed (GB 1 403 441) to use tread tires with a diameter of 666312 larger than the diameter of the carcass. Due to the larger diameter, the ring can be pulled over the carcass. In this case, the tread tires are about 4% longer or larger and this corresponds to an average additional length of about 12 cm in the length of the tire. The larger tread ring is placed in place and its dimensioning is adjusted to the diameter of the carcass. In this case, the tire material is often unevenly distributed on the carcass as a result of undesired tire imbalance as well as additional consumption of the tire material, causing additional costs without improving the quality of the final product.

The object of the invention is to provide an efficient method for renewing the tread of a worn pneumatic or all-rubber tire, by means of which high use value requirements for the tread tire to be treated can be achieved with less and less expensive means.

The object of the invention is based on the improvement of known methods so that the blank can be produced in a simple manner without the previously conventional cover for autoclaving and uncoated in the autoclave to vulcanize the binder layer.

This object is achieved and solved by the method according to the invention in that the tread tire is stretched with such force that the tread ring has a transiently larger inner diameter than the outer diameter of the carcass without stretching devices, and that the tread ring is placed on the carcass without stretching devices.

In the method according to the invention, the tread ring is stretched very strongly immediately before fitting it on the carcass in a simple stretching device so that when the tread ring is removed from the stretching device there is a short free elongation of about 3-4%, which allows in position, in exact position with respect to the circumference of the carcass. For example, about 4% free elongation decreases rapidly up to a residual value of about 1%. In any case, after the stretching step, the available duration of the short-term free elongation is sufficient to fit the tread tire over the 3 6631 2 carcass in a simple manner.

The amount of short-term elongation required for a tread tire depends on various factors, in particular the degree of free elongation desired and the composition of the tread material. In the practical tests performed, a commercially available tread material has used, for example, an elongation of about 100%, in which case the short-term free elongation is about 4%, but even lower degrees of elongation have proved to be sufficient.

Since the elongation and the short-term state of free elongation are applied to all parts of the tread tire, the elongation to the residual value also gradually decreases evenly throughout the circumference of the tire so that no imbalance occurs.

It is preferred that the lower surface of the tread ring has a roughening surface formed by protrusions and recesses forming a network of ducts made and pressed simultaneously with the tread in the compression molding.

Roughening of the tread with roughening machines immediately before it is applied is eliminated, as is the loss of rubber and the time required for roughening work.

The diameter of the unstretched tread tire can be dimensioned to be equal to the diameter of the carcass. In this case, the remaining amount of free elongation, which is only a very small percentage, can be easily compensated by twisting the tread ring placed on it.

However, it is preferred that the diameter of the tread ring before stretching is smaller than the diameter of the carcass, namely at least 1% smaller. As a result, after the cessation of the free elongation, no oversize occurs and the diameters of the tread ring and the carcass are finally equal. Finally, the choice of more than 1% less diameter of the tread ring before stretching results in the tread ring being under tension on the carcass because the diameter of the tread ring after cessation of free elongation is smaller than the outer diameter of the carcass. In this case, the advantage of easy fitting of the tread tire, which is provided with a transiently free elongation, is combined with the further improvement, 6631 2, that the tread ring is located tightly on top of the carcass. In addition, this results in the automatic removal of gaseous substances from the intermediate spaces. Since the tightening of the tread in its cross-section as seen on the convex carcass begins in the middle of the cross-section and continues to the sides, the gaseous substances are pressed to the sides and cannot form inclusions. If pressure is required in addition to this, a pressure strip or net may be used, as mentioned above.

If, when fitting the tread tire, only a small difference between the diameters of the tread ring and the carcass is preferred, it is expedient for the carcass coated with the bonding rubber layer to be provided with a plastic sliding film after the tread is applied to the tread.

Pulling out expediently takes place immediately after fitting the tread tire, before its free elongation is further reduced. The sliding film is applied on top of the horizontally placed carcass like a tablecloth so that the edge areas of the sliding film cover the circumference of the carcass at least up to its center, whereby the sliding film has a central centering hole, to easily center the sliding film. Also in the case where the tread tire is coated with a bonding rubber layer, a sliding film is applied over the carcass.

The method and apparatus according to the invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 schematically shows a stretching device used in the first step of fitting the tread to carcass.

Figure 2 schematically shows a second step in which a stretched tread ring is placed on top of the carcass.

Figure 3 shows a side view of the carcass in the second stage using a sliding film.

Figure 4 is a schematic side view of the carcass in a third stage in which the tread is pressed firmly against the carcass.

5,66312

In the method according to the invention for placing the tread in the form of a ring on the carcass 2, the tread ring 1 with a preformed roughening surface is subjected to an order of magnitude of about 100% (depending on the rubber compound, profiling formation, hydraulically movable roller movable in the direction of arrow 4 and 5 is stretched around a roller 5 suitably moving. In this only short-term stretching, immediately after release, the tread ring 1 acquires in the circumferential direction, for example, about 4% free elongation, which lasts for a short time and which gradually decreases to a residual value up to about 1 * after release of the tread ring 1 under load.

When the inner diameter of the tread ring 1 is exactly equal to or smaller than the circumferential diameter of the carcass 2 coated with the bonding rubber layer 6, namely 1-2% smaller than the diameter of the carcass, the tread ring 1 (cf. Fig. 2) can be easily and effortlessly fitted , whereby due to the transient elongation there is a small distance between the carcass 2 and the tread ring 1. In this case, it is essential that the tread ring 1 is placed on the carcass 2 immediately after the stretching event. Said distance is initially of the same diameters and with the same transient free elongation of 12 cm to about 2 cm, whereby it is possible to fit the tread ring 1 on the unobstructed carcass 2.

Depending on the choice of diameter, the cessation of elongation is rapidly achieved by the step shown in Fig. 4, in which the tread ring 1 rests firmly against the carcass coated with the bonding rubber 6.

Placing on the tread ring 1 can be performed without special aids, and the diameter space immediately after the stretching step makes it possible to place the tread ring 1 relative to the carcass 2, respectively, by moving it to a precisely centered position on the carcass 2. However, expediently so that the tread ring 1 can be fitted on the carcass 2 without special care 6631 2, a sliding film 7 of a very fine, adaptive plastic fabric with a central centering hole 8 (see Fig. 3) is preferably hung on a horizontally arranged carcass. After fitting the tread ring 1, the Liu film 7 is easily removed from the blank.

Yet another essential advantage of the invention is that the same tread size can be used over the entire tolerance range of the tire carcasses, whereby the necessary alignment can be performed by corresponding stretching.

When the third step according to Fig. 4 is reached, the preform thus treated can be subjected to vulcanization of the bonding rubber layer 6 to an overpressure state and heated. If necessary, a vacuum treatment of the desired quality can also be used to remove any gas occlusions between the superimposed layers. Prior to the overpressure heating, it is also possible to firmly and tightly connect the wear surface ring 1 at the outlet points on the sides of the binder layer 6 with carcase 1 by mechanical or chemical action, when the binder layer 6 is flowable immediately before vulcanization.

When the inner diameter of the tread ring is chosen to be smaller than the largest outer diameter of the curved carcass 2, as already described above, the gaseous substances automatically leave the intermediate spaces, because the fibrous ring 1 is tightened against the carcass 2 progressively from the center to the sides. The t.ie hyt network in the preformed roughening surface promotes the exit.

In order to fit on the tread ring 1, the carcass 2 is placed on a centering table with a funnel-shaped receiving or table surface, whereby carcases of different sizes can be coated on the same table. The fiberizing surface ring 1 can slide up to the inclined receiving surface and then always get a centered position with respect to the carcass 2.

Claims (6)

A method for renewing the wear surface of a worn air or full rubber outer surface, wherein the pre-treated body (2) of the ring is placed a bonding rubber layer and thereon an annular, prefabricated rubber wear surface (1), the inner diameter of which is smaller or as large as the body (2). outer diameter, whereby the wear surface is stretched for placement on the body, phase-shaped inclusions in the spaces between the adjacent layers are prevented or diverted therefrom, and the thus-made pre-fabricated ring blank is heated in autoclave to vulcanize the bonding rubber layer, 1) elongation is carried out with such force that the wear ring (1) is short-lived without elongation devices having a larger inner diameter is the outer diameter of the body (2), and that the wear ring is placed on the stonoun without elongation devices. Process according to Claim 1, characterized in that, due to the stretching of the wear ring (1), the subsequent short-lasting free stretching immediately after the stretching is about 3-4%. 3. A method according to claim 1 or 2, characterized in that the diameter of the wear ring (1) before the service is at least 1% smaller is the diameter of the body (2). 4. A method according to any one of claims 1-3, characterized in that the body (2) coated with the adhesive rubber layer prior to the sealing of the wear ring (1) is provided with a plastic sliding membrane (7) which is removed from the on each other's layers. 5. A method according to claim 4, characterized in that the sliding diaphragms (7) are spread on the horizontally positioned body (2) as a tablecloth. the edge regions of the sliding diaphragm (7) covering the casing of the body (2) at least as far as its center, the sliding diaphragms having a centrally located centering heel (8).