CS195734B2 - Method of making the on the whole surface depositable pre-vulcanised ring tread - Google Patents

Description

The present invention relates to a method for manufacturing an entire pre-vulcanized annular tread, section or segment having a molded M-shaped underside at the same time, for bonding capable of retaining rough surfaces from protrusions and depressions forming a network of channels and on top of tread designs , for the rebuilding of a tread of a pneumatic or solid rubber tire, in which a bonding layer of rubber and a pre-fabricated rubber tread are applied to the prepared tire carcass, for large tires with a rough pattern, preferably in the form of individual successive pattern or segment parts, eliminating or gaseous admixtures between the deposited layers and the thus prepared blank is heated in an autoclave to vulcanize the bonding rubber layer.

Plain and pre-cured treads are already known which need to be roughened on the underside to be bonded before being placed on the used vulcanizing sheath. This roughening of the lower edge is necessary both to remove the oxygenated layers that have been formed upon storage on the underside of the tread material and, on the other hand, to form molecules on the underside of the tread to ensure bonding to the bonding material during subsequent vulcanization. rubber layers and skeleton material.

It is also known to be capable of pre-vulcanized treads, the underside of which is intended as a bonding surface, which does not need to be roughened before being deposited on the carcass to be vulcanized and retreaded.

These treads have on their underside a rough surface which is formed simultaneously with the production of the tread itself and whose profile is arranged on the upper side of the pressing block. In order to store such a tread, the rough surface must be sealed to the ambient air. For this reason, a peelable layer of air impermeable material is applied to the rough surface of such tread, which can be deformed to match the surface of the rough surface. In order to achieve better protection against oxidation by ambient air, it is also known to provide a high-pressure foil between the unevenness of the rough surface and the facing side of the filler inside the press mold, which adheres to the later rough surface and exactly matches its unevenness. U.S. Patent No. 3,945,871).

Although the latter treads, in which the outer tread surface and inner rough surface are formed at the same time as the tread production and vulcanization in the press block, have proven to be very perfect, they still have some drawbacks that occur when using high pressure film. , which is applied to the later rough surface during the tread pressing and vulcanization.

The main drawbacks include the fact that when stored for several months the adhesion of the film to the rough surface is reduced, whereby air enters between the film and the rough surface so that the rough surface is oxidized. By this oxidation, the rough surface loses its surface activity, which is required in the later vulcanization to establish a reliable connection between the tread and the carcass. Therefore, even when using a protective film, the tread with an oxygenated rough surface cannot be placed on the carcass to be retreaded. If the tread is still used for retreading even after these deficiencies, the rough surface produced in the press block must be re-specially machined or manually roughened in order to remove the oxygenated layers on the underside and form there to bond a suitable molecule.

However, as a rule, such an additional roughening is not at all possible, or is, as in the case of annular treads or thin treads, for example, associated with considerable difficulties. Although it is possible to grind the oxidized layers on the rough surface of the oxygenated tread, the tread is usually unsuitable for circular retreading because it has oils and other components that the film applied prevents the tread from escaping through the rough surface. By this process, the tread material loses its tear resistance. Material changes also cause the proper connection between the tread and the carcass.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the pre-vulcanized tread of this type so as to prevent oxidation of the rough surface formed in the press block even after storage for several months and to prevent diffusion of the tread material components through the rough surface. In addition, due to improved adhesion and improved tread-to-carcass bonding, vulcanization methods suitable for all tire types should be used. If these methods require a rubber sleeve or rubber sleeve to wrap the workpiece and then apply pressure from the inside and / or from the outside to release gas impurities from the workpiece layers, it can be omitted in the method of the invention.

This object is solved by the invention which consists in that the rough surface formed in the pressing block on the underside of the tread is painted immediately after the tread is removed from the pressing block by a rubber-bonding layer.

This rubber bonding layer may be formed by any rubber coating compound which is applied to the rough surface formed in the molding block when restoring the sheaths used by the bonding solution of the rubber compound. > i ‘· - · '

Conventional solutions of this type are stored and contain unvulcanized natural or artificial rubber, with essentially three main types of solutions known.

The first contains natural or artificial rubber dissolved in petrol, benzene or trichlorethylene with sulfur as a vulcanizing agent.

The second solution is the same as the first solution, but in addition to the sulfur a vulcanization accelerator is added which does not activate at temperatures ¹ below 70 ° C.

The third solution comprises natural or artificial rubber, dissolved in gasoline, benzene or trichlorethylene with very rapid vulcanization but without a sulfur-type vulcanizer.

These solutions may additionally have components comprising bonding strength resins bonding rubber mixtures or oxidation protective agents. ’> ·

As is apparent from the foregoing, it is essential for the process of the present invention that by applying the solution to the rough surface, a film of unvulcanized rubber molecules is formed which, by simply applying petrol or benzol just prior to a later recovery process, is prepared without roughening for bonding.

Due to the application of the bonding rubber solution to the rough surface of the tread formed in the molding block, the rough surface cannot be oxygenated even when stored for more than one year. Compared to the release film, the deposited solution even forms part of the rough surface of the tread material; This completely prevents the release of the thus formed layer and the ingress of air between the layer and the rough surface of the tread, which reliably prevents oxygenation. In addition, the integral integral rough surface layers formed in themselves constitute an effective barrier against tread material diffusing and flowing through the tread material, making it impossible for these particles to leave the tread.

The effect of the layer formed by the rubber bonding layer as well as its formation is very surprising if the bonding rubber layer is applied to the rough surface formed in the press block, which does not need to be produced by mechanical roughing on special roughening machines, thereby only cutting out the contemplated connecting surfaces of substituents and molecules or portions thereof. The internal bonding that occurs after the die is withdrawn and shortly after being taken from the press block to the rough surface of the tread with a layer of unvulcanised bonding rubber compound dissolved in gasoline or benzol, etc., is explained by the solution joining unsaturated molecules in the rough surface. The structure of which is opened after removal of the rough surface from the metal-clean surface of the molding block, thereby realizing a physical non-chemical association. is: ion exchange between H-bridges of sulfite hydryl group. The surface of the coating solution remains activated and may be reactivated, if necessary, immediately before the tread is placed on the carcass.

After application of the solution to the rough surface of the tread, it is expedient to apply a protective film to the rough surface which is removed before the tread is deposited on the carcass. Basically, when using a fabric or the like as a matrix is also possible to reduce a loss in binding of said fiber ^fabric is removed from the rough areas just prior to use of the tread.

In the manufacture of the laminate structure, the bonding rubber layer is preferably applied in a plastic state. In fact, the plasticity imparts to the rubber bonding layer the fluidity necessary to flow into the rough surface. Plasticity is achieved either by using fresh bonding rubber, or by heating bonding rubber, or by adding the appropriate ingredients · Flowing bonding rubber · into the rough surface ensures an intensive connection between the bonding rubber and the tread before vulcanizing. This is an important prerequisite for curing of auxiliary means such as rubber sheath or wrapping etc. during the vulcanization. By treatment with heat and pressure in the autoclave, the bonding rubber flow is terminated.

The tread is applied to the carcass preferably with a ring-bonded rubber bonding layer and preferably under prestressing. There are several preferred processes for preparing the autoclave blank. Thus, it is possible to wrap the tread without the presence of air impurities on the carcass, provided with a layer of rubber bonding, starting from the center and continuing towards the sides so that the air impurities can flow to the side openings and escape there. This drain is favorably influenced by the tread, which is preloaded. Thereafter, the layer exit openings can be tightly closed to prevent re-entry of gaseous impurities into the laminate structure and secondly to provide additional securing of the laminate structure of the blank by sealing the exit openings.

In special cases, for example when applying coarse tread material, in particular in the form of individual sample parts or segments, it is advisable to lay a so-called ready-made tire loosely on the semi-finished product, which must not be confused with the hitherto usual high-quality rubber tire and laterally then seal the tire with vacuum and flood loose tread material. In this procedure, even with a very thin rubber backing layer, the tread material can be cast on the carcass without air impurities. The admixture is discharged by channel networks freely held on the hoop side.

The jacket is then removed and the outlet openings of the layers optionally sealed. .

At the same time, for the removal of air impurities and for attaching the tread to the carcass, the tread laid on the carcass may be surrounded by a flexible rubber or plastic pressure tape, which is advantageously made perforated or by means of a flexible mesh. The cross-section of the clamping band and thus the amount of pressure decreases from the center towards the sides, so that there is a gradual decrease in the pressure for the self-evacuation of the air admixtures to the sides, which is further amplified by the camber. The evacuation of the gaseous admixtures from the blank layers can be further facilitated by removing the admixtures through channels arranged to the sides of the tread, which channels can be made in the rough surface of the tread in the molding block simultaneously with the tread. .

The skeleton would. air pressure should be applied when adjusting, vulcanizing and putting on the rim. This is especially desirable for those types of skeletons that tend to shrink.

In addition to water, hot air, especially humid air and steam, can be used as heating medium in the autoclave. ........

If the carcass to be retreaded is damaged in the bandage, a tread can be used which has an upper and a lower part, the lower part being provided with steel fabric inserts, plastic fabrics, etc. For economical and reliable performance of the method The upper tread part is made as a separate part with rough surfaces on the joined sides in the press block and after insertion of another bonding compound · between these parts the two parts are gradually placed on the carcass.

Whereas the lower part is not extensible by the action of the inserts; it must be smaller when the annular lower part r, and the carcass is laid, or the carcass has to be wrapped around the carcass circumference at several points when the carcass is laid.

The process according to the invention is explained in more detail below in several exemplary embodiments; in conjunction with the drawing part.

Fig. 1 is an axonometric view of a rough tread made in a press block; . · '. · ·. FIG. 2 is an axonometric view. Fig. 3 shows a cross-section of a tread with a rough surface made in a press block on the underside and at the edges, Fig. 3 shows a cross-section of a tread with a rough surface made in a press block; surfaces made in a molding block with a different rough surface pattern,. . '.- · · · ·'. ·. Fig. 8 shows a cross-section of a blank which is lined with a tread composed of a lower and an upper part; Fig. 9 shows a cross-section of a ready-made tire or semi-finished product, with the tread edges under tension in the left half; Fig. 10 is a schematic representation of the carcass as the lower part of the tread is stretched.

The annular tread 1 shown in FIG. 1 has a rough surface 3 on its inner side and a tread 2 on its outer surface. Both of these surfaces were made during the manufacture of the annular tread 1 in a press block. Also, the tread segment 4 shown in FIG. 2 and provided with a rough tread 2 has an inner rough surface 3 and a rough surface 5, B of the gates at the points where the bonding by the bonding rubber is to be established. Depending on the type and shape of the block, it is possible to select the structure of the rough surface 3 and to determine the sizes and distances of the projections 14 and the depressions 15 provided between them (see FIGS. 4 to 7). It is also possible to produce undercut projections as shown in FIG. 6. FIG. 7 shows a rough surface structure 3 which can be produced simply by creating uneven depressions 15 in the upper half of the press block or in the lid of the press block.

It is clear that the described uneven depressions containing the rough surface 3 already form a sufficient network of channels for evacuating gaseous and liquid impurities from the layered structure of the hoop to be formed.

Fig. 8 shows a layered structure of a manufactured tire, the carcass of which is provided with a tread or annular tread having an upper part 1a and a lower part Ib provided with inserts 11. The lower part 1b forms a reinforcement of the carcass 8 whose strips have been damaged and partially ground in preparation of the retreading frame 8. The lower part 1b has rough surfaces on all sides, these rough surfaces being made in a press block. The lower side of the lower part 1b is connected via the rubber bonding layer 10 to the upper side of the carcass 8. Another rubber bonding layer 9, arranged around the lower part 1b and expediently over the lower part 1b, connects the upper part 1a with the lower part 1b and refers to the edges of the annular tread 1, the upper part 1a with the carcass 8. The deposition of the rubber bonding material or strips 12 illustrates how the side exit points 12a are closed on the sides of the laminate before one of the above mentioned methods exerts a negative pressure on the laminate manufactured hoops for evacuating gaseous and / or liquid admixtures.

It can be seen from the left-hand part of FIG. 9 that by placing a rubber bonding tape 12 under the protruding edges of the tread or annular tread 1, a preload can be applied at this point to secure the layered structure to the carcass 8.

It can be seen from the right-hand part of FIG. 9 how the liquid and / or liquid rubber is discharged, particularly in the case of thick profiles with a thin rubber layer, not shown here. gaseous admixtures below the protruding edges when the ready-made tire 13 has been connected to a vacuum, while the annular tread 1 or its upper part 1a is initially only loosely deposited and then rolled from the center towards the sides. Suitably, the ready-made jacket 13 is sealed to the rim 16 by a rim 17 and the admixtures removed laterally pass through a recess 15 formed in front of the projection.

14. Before placing the blank into the autoclave, the ready-made jacket 13 is removed.

FIG. 10 shows only schematically how the circumference of the casing and hence the diameter of the carcass 8 must be reduced if the non-extensible lower part 1b of the annular tread 1 is deposited on the carcass 8, for example. for example in a symmetrical configuration, they are pressed into the carcass 8 along its circumference and thus allow the lower part 1b of the annular tread 1 to be stretched.

Claims (5)

Subject A method of manufacturing a full-surface pre-vulcanized annular tread, section or segment having a molded on the underside at the same time as a molded part for bonding capable of retaining rough surfaces from protrusions and depressions forming a network of channels and Tire reconditioning of a pneumatic or solid rubber tire, in which a bonding layer of rubber and a pre-fabricated rubber tread are applied to the prepared tire carcass, for large coats with a coarse pattern, preferably in the form of individual, successive pattern or segment parts, eliminating or gaseous admixtures between the deposited layers, and the thus prepared preform is heated in an autoclave to vulcanize the bonding rubber layer, characterized in that the rough surface formed in the tread at the bottom of the tread is painted immediately after removal. wipes the tread from the press block bonding the rubber layer. 2. A method according to claim 1, characterized in that a curing reaction, for example silicone, is applied to the surfaces of the molding block or the rough-forming matrix, or directly to the surface of the blank inserted into the molding block. Method according to claim 1 or 2, characterized in that the blank or the filling of the compression molding block for the production of the annular tread is injected into the pressing molding block. Method according to one or more of Claims 1 to 3, characterized in that the channels leading to the sides of the tread are produced in the rough surface simultaneously with it in a pressing block. Method according to one or more of Claims 1 to 4, characterized in that a carcass consisting of an upper and a lower part is placed on the carcass, the lower part having inserts preferably made of steel or a bandage of plastic or textile fabric. Method according to claim 5, characterized in that the lower part and the upper part of the runount are produced as separate parts with rough surfaces on the joined sides in the press block and are gradually deposited on the carcass as the intermediate rubber bonding layer is inserted.