HU197694B - Method for producing tyres - Google Patents

Abstract

The present invention relates to a method for producing pneumatic tires, wherein the pneumatic tires are constructed in the form of a drum or flat assembly technology in the form of a cylinder, an internal variable circumferential ribbed pneumatic template (5) is inserted into the cylinder, and the cylinder (6) is formed into a cylinder. after completion of further forming operations, after the loss of internal pressure is lowered or removed, instead of forming tools at each step of the process, the desired shape is provided by means of an air pressure and diameter defining element suitable for the stress-free equilibrium state of the structure, the bombardment and the diameter. during vulcanization. //; —7—7% Z abra -1-

Description

The present invention relates to a process for making tires.

It is known that wheeled vehicles are diversified technical developments and specialization areas of application between the vehicle and the ground or, more broadly, the vehicle (wheel, mud, mud, sand, snow, ice, water) , etc.) and the need for specialization. As a result, there is a huge need for variations in the structure, shape, dimensions and types of pneumatic tires for vehicle development. This rapidly expanding and diversified technical need cannot be satisfactorily met, either technically or economically, by conventional methods of tire production.

The fact that it usually takes 2-3 years to develop and start a new type of tire is a barrier to technical progress. However, this turnaround time is significantly extended when it comes to special tire types, such as tire sizes that are much larger than normal and / or significantly different in shape and / or specific performance, such as floating and all-terrain tires.

The length of the development work is primarily due to the complexity and geometry of pneumatic tires, whose quality and lifetime are highly dependent on:

the equilibrium shape of the vulcanized tire (that is, the degree to which the tire shape, prior to inflating, approximates that of the tire when fitted and inflated);

the geometric accuracy of the tire and its components;

and the intrinsic strength of the structural members and the bonding strength of the contacting members.

For this reason, special purpose machines, construction machines, vulcanization molds and often vulcanization machines are used for development work and start-up, as well as for small series, essentially for mass production. In the case of Type C tires, the development of tires is often preceded by the development of such complex and large mechanical structures.

New types of tires are extremely expensive just because they are small series in the early stages of development and distribution. This high tire cost also has a disincentive effect on vehicle development. The only solution to this problem is to lease special small-series tires.

Therefore, the process and equipment 2 for producing tires, and in particular for new type special tires, must at the same time satisfy the following complex set of requirements.

First of all, the process must allow the production of any of the large pneumatic tires required for vehicle construction and vehicle operation. Here, the diameter and width of the tires can be up to several meters, in practice the upper limit can be set at five meters. One of the new applications is the development of special vehicles, where the increase in size is usually justified by an increase in load capacity or a reduction in ground pressure.

Another area of application is the fitting of existing vehicles with wider tires, the main advantage of which is that they can reduce the ground pressure and replace dual or triple twin tires with a single tire.

Secondly, it is essential that the process and the equipment for carrying it out allow minor changes in the shape and function of the pneumatic tires to be made. With regard to the shape of the tire, the primary purpose is the possibility to easily change the profile height, the profile width and the profile length, as well as the rim diameter. In particular, internal pressure, load-bearing capacity and off-road capability must be taken into account.

It is also a goal that the tires are produced in exactly the equilibrium form. This means that after fitting and retreading of the finished vulcanized tire, unnecessary and harmful stresses in the tire will not enter. This requires the production process or, where appropriate, the development of equipment which allows the tires, from bombing to curing, to be free from any adverse effects which would impede the formation of equilibrium, so it has been found that a solution look for which eliminates any obstacle in the shape and retention of the tires due to the stiffness or friction of the outside of the tire. In addition, it is obviously necessary to eliminate geometrical distortions of gravity effects caused by the self-weight.

It is also desirable to ensure that the structural members of the tires themselves are of high strength and that the strength between the elements is also perfect. For this, obviously, in addition to the structural materials selected in the usual way, the compactness and continuity of the structural members are required, i.e., no pores or separation in the tire structure.

In order to make experimental products and small batches at a reasonable cost, el-2197694, complicated and expensive construction machines, vulcanisers and vulcanizers need to be eliminated.

The technical and economic reasonableness and importance of the requirements listed is evidenced by the fact that such developments are apparent from numerous patents; however, the solutions so far have only partially met these requirements.

In particular, according to the patent literature, it has been unsuccessful to develop a method and apparatus which allows small variations in shape to be varied within wide limits, to achieve accurate equilibrium shape and geometry, and to eliminate costly mechanical structures.

Of the many patents that reflect these endeavors, only the most representative are referred to below.

Overcoming the difficulties of increasing the size of tires is covered by several patents. U.S. Pat. No. 4,142,930 discloses a method of vulcanizing tires at high profile widths and low profile heights, which are then mounted at low profile widths, which increases the outer diameter of the tires when inflated when mounted. In this way, it is obviously possible to produce large tires, but deformation, in particular changing the profile length of the profile, is in sharp contrast to the requirement of equilibrium and requires conventional, expensive target machines and a form of vulcanization.

The solution disclosed in U.S. Patent No. 4,152,191, although suitable for the production of large, annular bodies, is intended for use only in the manufacture of interchangeable runners, and it is obviously not possible to produce a complete tire.

According to British Patent No. 1,516,553, the tire is manufactured in several steps with a complicated structure and the solution does not provide for the requirement of equilibrium shape and simple deformation.

According to French Patent No. 2,271,920, the equilibrium shape is achieved at some stage of the production, namely, the tire is bombarded freely. However, the suspension due to the vertical arrangement, especially in the case of wide tires, damages the exact geometry of the structure, and during vulcanization after bombardment there is no guarantee of maintaining the exact equilibrium shape.

A sophisticated vulcanization machine and form system is proposed in U.S. Patent No. 21,522,863, so that the process does not involve simple deformation and accurate equilibrium.

Finally, U.S. Patent No. 3,926,711 to vulcanize the tread of large tires in a rotating structure. However, this only applies to retreaded or repaired tires that have a given carcass, that is to say, are already in shape, so that the solution is obviously unsuitable for the production of new tires.

The process and equipment proposed in British Patent No. 1,380,997 are to some extent suitable for the manufacture of tires that can be varied over a relatively wide range, however, even when changing the profile length, some modifications are required here, and the vulcanization after free bombardment is similar in this case. This means that the exact balance is not guaranteed.

In order to provide equilibrium shape, more specifically once formed, relatively simple structures have been proposed in several patents for repairing or retreading used tires. Thus, the aforementioned U.S. Patent No. 3,926,711 discloses the retreading of large tires in a boiler using a relatively simple structure for repairing tires in accordance with U.S. Patent No. 3,895,985. U.S. Patent No. 3,151,027 and U.S. Patent No. 28,163,143 also disclose a simple, non-cured vulcanization process for retreading used carcass tires. However, these processes are completely unsuitable for making new tires.

The pursuit of equilibrium shape and accurate geometry is reflected in the descriptions which see the solution of the problem in vulcanization. For example, U.S. Patent No. 1729,633 discloses that the carcass and / or the carcass and the cushion layer or belt are pre-vulcanized and then cured to provide accurate carcass geometry. This two-step vulcanization is also characterized by the process described in German Patent No. 22 08341. In such a multi-step vulcanization, the exact equilibrium shape can be doubled due to the compelling effect of the vulcanizing forms. A further disadvantage of these processes is the dual mold design. A specific process is directed to British Patent No. 1,471,547, which provides a solution for the precise design of the inner and outer geometry of tires, in particular radial tires, whereby the tires are built up from the outside to the inside in a vulcanized form. However, in this process, too, there is no guarantee of an exact equilibrium shape. Of course, the last three patents do not

-3197694 also fulfills the requirement of easy-changing tire guardianship.

Bombardment without free and inner membrane (balg) is disclosed in U.S. Patent Nos. 4,181,483, 3,917,791, 3,994,559, and 1,430,262, and U.S. Patent 4,400,342. Patent No. 4,268,198. The latter also describes the modification of existing well known membrane vulcanization machines. These processes have the common advantage of solving the curing problems of off-road vulcanization, but have the disadvantage that they do not eliminate the need for a vulcanization mold or machine and therefore do not guarantee equilibrium shape and do not permit the easy manufacture of wide range tires. .

Methods of equilibrium appear to be achieved by the processes described in U.S. Patent Nos. 30,303,822 and 1,929,402. However, these only apply to bombing, and the subsequent vulcanization has the disadvantages (inaccurate equilibrium, heavy deformation) mentioned above.

Several methods are known for increasing the strength of the tires or their structural members and the adhesion between the members. These include trends that increase the internal pressure of molded vulcanized tires.

Obviously, these methods do not automatically provide equilibrium shape and precise geometry, simple deformation, and are extremely expensive. In essence, the same applies to the following procedures, which follow relatively novel paths.

According to U.S. Patent No. 806,458, a mixture of steam and nitrogen gas is used as a heating medium for vulcanization in the form. U.S. Patent No. 859,188 does not relate to tires, but to rubber goods in general, and recommends the use of a vacuum during vulcanization. According to U.S. Patent No. 927,543, the use of molten and aluminum spheres for internal heating of molded tires is preferred. U.S. Patent No. 975,439 proposes a complicated vulcanization process in which tire tires are rotated about a horizontal axis in a vertical plane. Finally, in order to achieve uniform vulcanization, U.S. Patent No. 804,503 proposes to inject the fuel in a radius of various shapes to vulcanize the mold.

In conclusion, the complex system of requirements described above has not yet been satisfactorily met by known processes, in particular the known processes are inadequate in that they do not consistently maintain equilibrium during the forming operations, including vulcanization. making tires of different shapes by simple methods and usually require expensive special purpose machines or vulcanizing tools.

It is an object of the present invention to overcome the disadvantages of the prior art.

In order to accomplish this object, the present invention has been based on the following principles.

In order to obtain arbitrary sizes, especially giant sizes, only reasonable cutting operations and simple structures are used, at most using auxiliary structures which are capable of carrying the unladen weight of the raw tire at larger sizes, but without affecting the equilibrium shape of the tires. It is also accomplished simply by tailoring operations and simple auxiliaries to produce differently shaped tires using essentially the same process and almost identical equipment.

It is an object of the present invention to recognize that the equilibrium shape of the process is achieved and maintained throughout the process solely by the internal pressure of the raw or vulcanized tire, more particularly by the difference between the internal and external pressures. The process of the present invention consists in forming the inner carcass of the pneumatic tires by drum or flat assembly technology, by inserting an inner variable circumferential ribbed pneumatic template into a cylinder and, upon completion of further forming operations, by releasing the internal pressure. lowering or removing until, at each step of the process, the desired shape, which corresponds to the stress-free equilibrium during construction, bombardment and vulcanization, is obtained by means of a tire pressure inside the tire and by means of a diameter penetration element.

Example

In accordance with these principles, the process of the present invention will be described in detail with reference to the following figures:

Figure 1 Construction of tire layers on a flat table top

Figure 2 Variable circumferential ribbed pneumatic template

Figure 3: Further construction of rolled-up raw tire

Figure 4 Tire bombing in final state

Figure 5 A closer look at a non-elastic belt

Figure 6 Free-space vulcanization

In the first step of the process, the profile ribs length-4197694 of the tire to be fabricated are made of the appropriate ply layers in a conventional manner on a rigid or inflatable drum.

However, for larger sizes, it is desirable, as shown in Figure 1, to lay the layers 1 on a flat table top 2 by joining the layers on the rigid table top with a roller 3 and forming the endless roll in a flat form. In order to prevent fractures, auxiliary rolls 4, such as paper rolls, are inserted into the loop-like bends. For this production stage, conventionally prepared rubber mixtures, discs, rubberized cords are used.

The cylindrical tissue body, which has been removed from the drum and then flat, is then internally provided with a variable circumferential ribbed pneumatic template 5 which, in its inflated state, forms a cylinder 6 as shown in Figure 2. The 5-variable-rib ribbed pneumatic template is made of a thin-walled flexible material that does not interfere with further forming operations when lowered; The diameter of the ribbed pneumatic template is adjustable by means of a perforated ribbon 7 which can be threaded along the periphery of the template. The template is inflated using the 8 valves.

The rolled pneumatic template 5, which is cylindrical and has a variable circumferential ribbed pneumatic template, is provided with self-supporting and geometrically high precision end plates 9 (with end discs provided with conventionally made wire rings 10, just like this one

Figure 3 shows.

Then the cylinder 6 formed by the variable circumferential ribbed pneumatic template 5 is lowered by means of a valve 8 which is guided through one of the end discs 9 and the bombing is also started by means of the air introduced through the end disc 9. Inert gas may be used instead of air for this purpose. During the bombardment, due to the virtually frictionless approach of the end discs 9, the sidewalls of the tire are perfectly balanced. The final state of the bombardment is determined by the non-elongated belt 13 shown in Fig. 4 in the circumferential orientation of the cylinder. The placement of the belt 13 is shown in greater detail in Figure 5, where it is shown that the belt 13 is held by the vacuum suction cups 14 in the desired central position. As stated above, the profile length of the tire to be produced is essentially the length of the cylinder and the height of the profile is determined by the circumference of the belt 13. These parameters can thus be varied within arbitrary limits, simply by cutting raw semi-finished products, rubberized cords, or raw composite sheets. The rim diameter of the tires can be varied by changing the size of the locking discs and the locking rings 11 and the pe8 ring rings.

During the bombardment it is important that the proximity of the end discs 9 is frictionless and that the equilibrium shape thus obtained can be recorded. This can be easily accomplished with appropriate simple structures. Such a low-friction solution is, for example, the simple, sliding tubular shaft 15 of FIG. 3, with appropriate bearings.

When the bombardment is complete, the various running layers or ribs are applied.

After the tire is fixed in this equilibrium shape, it is cured. During vulcanization, the position of the rim of the tire and the position of the end plate 9 and the latching belt 11 remain unchanged, and the difference between internal pressure or internal pressure and external pressure is also the same. Otherwise, this internal pressure value should be chosen so as to be equal to or close to the operating pressure of the tire.

There are two ways to cure vulcanization. One method is to vulcanize in the open air as shown in Figure 6 by heating the inner air space 16 of the tire with a heating system 17 introduced through one of the locking discs 9, circulating the warm air with the fan 18 and avoiding heat loss from the outside 19. thermal insulation. In this case, the temperature should not exceed 100 ° C for high strength, compactness and good adhesion. Obviously, this type of vulcanization generally takes longer than conventional tire production processes, but due to other advantages, this time investment is profitable. This vulcanization mode is surprisingly well-cured and results in long-lasting tires in which both the strength of the components and their bonding strength are adequate. This can be explained by the fact that conventional methods are used to increase high strength and cohesiveness by increasing temperature and pressure, thus relatively "expensive" methods, whereas in the process of the present invention, increasing the time factor is used to compensate for the reduced effect of temperature and pressure. rather economically. This outdoor cure is particularly recommended when it comes to relatively large sizes and small series or possibly individual pieces.

In the other vulcanization mode, the fixed-distance end discs 9 place the tire in a heated space such as a boiler and then, by means of a suitable structure, ensure that the internal pressure of the tire during vulcanization is slightly higher than the overpressure.

-5197694 like the pressure in the boiler. In this case, the temperature can of course be increased in proportion to the pressure conditions and thus the cure time is reduced. This process is not particularly bulky and is advantageous for larger series of tire products.

For both types of vulcanization, it may be necessary to use certain auxiliary devices to prevent undesirable deformation caused by the self-weight. This is particularly necessary if the tires are made of technical, economic, thermoplastic materials, such as low molecular weight rubber or low heat-fixed fibrous materials, or have very high wall thickness and low internal pressure during bombing and vulcanization. In this case, the auxiliary devices are intended solely to ensure that the tire is self-supporting even when heated, so that its own weight does not alter its equilibrium shape or geometric accuracy.

Claims (9)

PATENT CLAIMS I. A process for producing pneumatic tires, characterized in that the inner carcass of the pneumatic tires is drum-shaped or flat-assembled, cylindrical, fitted with an inner variable-ribbed pneumatic template (5) and then rolled (6). at the completion of further forming operations, after relieving of internal pressure, is lowered or removed, and at each step of the process, the desired shape of structure, bombardment and during vulcanization. A method according to claim 1, characterized in that the tires are cylindrical 5 carcasses are closed with end plates. Method according to claim 1 or 2, characterized in that the element for limiting the increase in diameter of the cylindrical carcass is the organic part of the tire. 10 forming belts (13) are used. 4. Method according to one of claims 1 to 3, characterized in that the position of the belt (13) is fixed mechanically or by means of vacuum t15 (14) before forming the cylindrical carcass. 5. A method according to any one of claims 1 to 4, characterized in that the tire structure consisting of a cylindrical carcass and belt (13) is formed by gradually increasing the pressure of the air or inert gas introduced across the cylindrical end plates. 6. A method according to any one of the preceding claims, characterized in that the formed tire is pressurized In its 25 state, it is provided with the appropriate components, preferably with elements protecting the sidewall and running and gripping organs. 7. A method according to any one of claims 1 to 3, characterized in that the tires are vulcanized by means of a heating system (17) introduced through the end discs (9). 8. Figures 1-7. A method according to any one of claims 1 to 4, characterized in that the tires to be vulcanized are provided with a suitable insulating jacket on the outside. 9. Figures 1-8. A method according to any one of claims 1 to 4, characterized in that vulcanization is carried out in a pressurized enclosure while the internal pressure of the tires is always maintained above the pressure of the pressurized enclosure.