Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-02-11
2002-06-18
Knable, Geoffrey L. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S111000, C156S128100, C156S130000, C156S130500, C156S133000, C264S502000
Reexamination Certificate
active
06406575
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 199 05 643.9, filed on Feb. 11, 1999, the disclosure of which is expressly incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing a pneumatic tire, e.g., for motor vehicles, that includes a build-up of the tire with an inner liner of a layer that is as air-impermeable as possible, at least one carcass ply provided with strength supports, horn profiles, bead cores, sidewalls, a belt assembly, an optional one-part or multi-part belt bandage, and a tread. The production process is divided into two separate production parts A and B. In production part A, a partial tire is built up and includes at least the carcass body provided with reinforcing plies, bead reinforcements and cores, core fillers and horn profiles, optionally, parts of the belt plies and/or the belt bandage, and the undertread. The partial tire is shaped and then at least partially vulcanized under internal pressure in a vulcanization mold in a first vulcanization procedure, in which a predetermined cross-section contour is imparted to both the surface and the strength support(s). In production part B, the partial tire is built up by adding the remaining tire components, essentially the belt assembly, optionally, the at least single-ply one or more-piece belt bandage, the tread, and the remaining sidewall parts, thereby producing a complete tire. The complete tire undergoes a second vulcanization procedure in a vulcanization mold to bond the partial tire to the remaining tire components, during which, a residual elevation produced by internal pressure is applied, and the complete tire is molded to its final contour.
2. Discussion of Background Information
In a production process for new tires different from the conventional process, the known build-up of the tire carcass is carried out on a first building-up drum and the further build-up to produce the finished green tire is carried out on a second building-up drum that includes a shaping part and on which the carcass is joined with the belt tread packet. It is customary to use a one-step process in which the carcass production and the preparation of the green tire takes place on a single building-up machine with several building-up drums.
The prepared green tire is fully vulcanized in an appropriate vulcanization mold and, thus, receives its final form with a molded-in tread profile.
In this situation, there is always the problem that, during the shaping of the cylindrical preform to produce the torus-shaped tire body and during the vulcanization, in which internal pressure is applied to the preform via a bellows and in which the preform is placed under elevated temperature to receive its “residual elevation,” it must be considered that the geometry of the carcass can change as a result of each expansion procedure and also that the volumes of the superimposed rubber layers, e.g., the volumes of the tread or of the rubber parts of the sidewall, can be displaced. Adjustment for this change in geometry, which is ascertained empirically, must be undertaken in advance to compensate for it. However, such compensation or adjustment holds the dangers that, e.g., in the areas particularly subjected to the expansion, exact dosing of the rubber volumes and exact shaping are difficult.
Thus, generic processes and devices have continually been suggested in which first an at least partly vulcanized green carcass is produced and the outer plies of the tire are subsequently applied onto the green carcass or carcass body whose contour already corresponds essentially to the finished tire. DE-PS 14 80 936 shows a tire in which a vulcanized running ring with a belt-type reinforcement is bonded with an unvulcanized or merely prevulcanized tire body or a tire carcass, after which the total tire is fully vulcanized. However, the disadvantage of this process is that a further layer, which ensures the adhesion of the individual parts to one another, must be inserted as a rule to bond the carcass and the tread.
As in previous processes that suggest a separate production and vulcanization of a carcass body and its subsequent bonding with the remaining tire components in a separate manufacturing procedure, the problem arises that, due to the second shaping required to combine it with the remaining tire components, increased stresses and compressive strains are introduced into the reinforcing plies and, in particular, also into belt plies already present, i.e., by the residual elevation of the already vulcanized and shape-stable carcass. These stresses and strains can have a strong influence on the durability of the tire. An inserted adhesive or bonding layer to reduce the second shaping of the already vulcanized and shape-stable carcass does not fundamentally solve this problem, since this has a disadvantageous effect on the vulcanization process.
In addition, a conflict in aims arises in such a two-part production process. In particular, the individual radially adjustable circumferential segments of a vulcanizing mold customarily designed as a segment mold should, if possible, have only a small displacement or adjustment path in the radial direction for closing the mold. Otherwise, the rubber material is strongly squeezed at the closing segment edges and a flow component occurs that is directed into the closing gap and radially outwardly, which strongly influences tire uniformity and, therefore, requires subsequent work. However, to apply, e.g., the necessary vulcanization pressure among other things, such a small displacement or adjustment path in the radial direction requires a large residual elevation, which, as discussed above, produces the undesirably increased stresses and strains in the carcass components, i.e., in the reinforcing plies and, in particular, also in belt plies already present.
The results of defective tire uniformity are evident in an unsatisfactory running behavior, in increased development of noise, and in a strong load on the bonding areas during operation.
The process disclosed in DE-OS 20 32 636, in which a treadless tire casing, i.e., a carcass body first produced as a partial tire, then provided with a lining and subsequently partly vulcanized, shows precisely the same disadvantages. In this partial vulcanization, the inside of the tire casing is fully vulcanized, while the radially outer surface of the treadless tire casing is not vulcanized. Across its cross-section, therefore, a half-fully vulcanized treadless tire body with a lining is available for further manufacture.
The lining is intended essentially to protect the partial tire, i.e., the part of the tire casing which is not fully vulcanized, from detrimental influences during an intermediate storage period. At a later point in the manufacture, the lining is removed and a tread is applied onto the treadless tire, whereafter the finished tire can then be fully vulcanized under pressure and heat.
DE-PS 17 29 633 describes a process for producing a pneumatic tire in which a carcass is prevulcanized only so that the reinforcing or fabric plies already present are fixed to such an extent that a serious displacement of them during the subsequent full molding of the profile is no longer to be feared. While it is true that the frequently described problem is solved, i.e., that a displacement of the reinforcing plies can also take place during the impressing of the tread profile as a result of the displacements of the volumes in the not yet vulcanized rubber, which has a detrimental effect on the later strength of the tire, the introduction of stresses and strains into the carcass components is not prevented here either, and also this conflict in aims is not resolved.
SUMMARY OF THE INVENTION
The present invention provides a process for producing a pneumatic tire in which an at least partially vulcanized carcass is first produced as a partial tire and the partial tire is built
Baumgarten Rainer
Campsheide Olaf
Fries Volkmar
Jenke Roland
Continental Aktiengesellschaft
Knable Geoffrey L.
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