SE444533B - DEVICE FOR MANUFACTURING ONE OF ATMINSTONE TWO LAYERS OF DIFFERENT MATERIALS CONSISTING HOSE, WHICH WALL THICKNESS IN VARIOUS INTERVALS IS THUNDER AND THICKER - Google Patents

Description

15 20 '25 30 35 8003723-7 The inner liner forms the innermost part of the tire, where the inner hose comes into contact with the tire. In the case of the now common tubeless tires, the innermost layer consists of butyl rubber because this material has about 8 times greater air permeability than natural rubber, while the second layer consists of a natural rubber mixture to ensure a good transition to and best connection with the next up - building layer.

However, it is very difficult to connect butyl rubber mixtures with other elastomer mixtures, especially in the cold state, which is why the inner liner profile of butyl grade is already combined with the transition rubber in advance, and this is done whenever possible when both grades are in the hot state. ; This is currently happening around the world. through a very labor-intensive and costly production process on plates and duplication calendars.

An inner liner of a contemporary type, for example for a small truck tire, is then constructed approximately in accordance with the embodiment shown in Fig. 1 of the drawing.

Since rubber compounds on calendars can only be made with a thickness of up to 1.5 or a maximum of 1.8 mm if they are to be somewhat free of blisters, the upper layer is calendered in a natural rubber mixture (or synthetic transition mixture) in two foils 1.1 and 1.2 (Fig. 1) with a thickness of 1.5 mm, and cut to then be doubled on the doubling calender with the lower layer of butyl rubber, which is also produced in two layers 1.2 and 1.4 (Fig. 1), wherein each foil is 1.8 mm thick.

Already in the production of the foils themselves on the calender, blistering during calendering can not be completely avoided at the material thicknesses chosen. When doubling, however, blistering (air inclusions) always occur between the separate foils and at the overlaps of the finished profile plate. This has a strong negative impact on the quality of the finished tire.

Perhaps the most difficult problem when handling inner liners when building tires on the builder, however, is the so-called the splitting, i.e. the assembly point at the ends of the innerliner profile.

If the inner liner profile is composed of calendered foils, this suitably forms an open strip which is mounted on the builder's drum endlessly as a hose ring. Although the obliquely cut end portions of this flat inner liner profile are made prone to contact either by solvent or by any adhesive solution, before being laid on top of each other, and even if the builder operator pays the most attention and extensive working time to the splicing site, and thus inaccuracies at this assembly site, which mostly results in tearing of the splitting site and scrap.

That tearing occurs is understood if one considers that the inner liner is stretched to double length before it, together with other separate parts, is vulcanized as a built-up deck.

At the same time, the poor propensity of the butyl material to bond with other elastomers should be taken into account, whereby the builder operator has not always succeeded in laying exactly line by line of the same material in the end portions of each other when splitting the inner liner profile on the builder drum.

Another inconvenience with calendered innerliner profiles is the fact that too much material is used sideways, which material could then be saved. The optimal design for an innerliner profile strip could be approximately in accordance with the design according to Fig. 2, from which it is shown with dashed liner which material could be saved in addition to the calendered innerliner. The invention relates to a device for producing such a hose, which device is characterized in that the said means consist of elastic pulsation rings, which are arranged in grooves in the outer disc of the spray head and / or its inner mandrel. , wherein means are provided for more or less expanding the pulsation rings in a controlled manner by supplying gaseous or liquid media in a controlled manner. The basic idea in eliminating these problems is that instead of an open profile band which must be split on the builder, a closed one is used, i.e. endless belt in the form of a hose section, which can be laid or slid over the builder drum by the builder operator in a few seconds. ' The invention will be described in more detail below in the form of exemplary embodiments with reference to the accompanying drawing.

Fig. 3 schematically shows a piece of hose manufactured in accordance with the invention. Fig. 4 shows a double spray head according to the invention, for carrying out the method, and Fig. 5 schematically shows a section of a spray head with means for generating a wave-shaped wall in a hose.

Since the inner liner in the middle along the largest radius of the inner diameter of the tire must be relatively thick (Fig. 2) and laterally tapered towards the smallest inner diameter of the tire where the rim rests, a hose must be extruded, advantageously in a workflow, with two rubber grades which at accurately or precisely controllable and adjustable intervals are thickened and thinned at axially always equal places, whereby these thickenings and thinners must always be radially equally continuous and centric.

Such a hose 2 is shown in Fig. 3 of the drawing. The separate inner requirements are formed by separating the hose sections 2 ', 2?'. etc. at the thinned points 3, 3 "etc. -_- --- 1 10» 15 20 25 30 35 ~ 80037257 When using such closed rings or hose sections, which may, for example, have an inner diameter of 500 mm and a length of 800 mm, the following significant advantages arise: much less work effort both in the production of this inner lining and also on the builder, ie in the construction of the tire; In less energy consumption; large material savings; ~ no splicing work (assembly work) on the builder which means no adhesive solution needs to be applied at section points; the profile strip length becomes uniform at all times, so that profile displacement (eccentricity) can also be avoided and no tearing occurs as there is no assembly point; completely air- and dirt-free connection between the two elastomer layers; end product, minor scrap.

Fig. 4 of the drawing shows a double spray head 4 in which two different plastic masses are extruded simultaneously with two spraying devices and can be formed into a hose with superimposed layers.

The two extruders (not shown) are arranged at an angle of preferably 450 towards the axis of the spray head, so that a good material flow is obtained towards the outlet 5 of the extrusion head 4. The materials flow via two machined sleeves 6 and 6, respectively. 7 with flow direction fins 8 resp. 9 about each other and meet each other around at the end of the intermediate sleeve 6 with great pressure and in a condition that offers the best plasticity to get a good connection. Means are arranged to offer the possibility of varying the wall thickness of the hose to be formed at accurately determinable and controllable time and time intervals, respectively. longitudinal sections also to a precisely determinable extent so that the hose wall will be thinner and thicker with a stretch that runs approximately along a desired road line (see Fig. 3). This change, i.e. pulsation in the material supply is achieved in that perforated rings 12,13 of elastic and heat-resistant material (pulsating rings) are inserted in occupied grooves 10,11 both at the material flow at the outer disc 9 and at the inner mandrel 8 according to Fig. 5, which perforated rings are externally loaded with gaseous or liquid media and thereby can be destroyed resp. is reduced in a controlled manner, so that the material throughput is correspondingly reduced resp. enlarged (see Fig. 5 the dashed lines 14 and 15, respectively) at the pulsation rings 12 and 15, respectively. 13 wherein the outgoing hose at the passage of the clamping point, i.e. the narrowest place between the rings 12,13 becomes thinner. The intervals for the pulsation are controlled by means of units not described in detail, known per se.

However, pulsation can also be achieved by axial displacement of the inner mandrel 8 and / or the outer plate 9, whereby the material flow between the inner mandrel 8 and the intermediate sleeve 6 on the one hand and the outer plate 7 and the intermediate sleeve 6 on the other hand is varied.

The variation of the material flow, i.e. the pulsation, can of course also be achieved by displacing the intermediate sleeve 6 in the axial direction.

Pulsation can also be achieved by changing the worm speed at the extruder (not shown), or by changing the stripping speed.

A further possibility lies in providing pulsation by means of a hydraulic cylinder which provides the material transport through the spray head 4 instead of shells in the extruder, and / or which in addition to the shells acts as a pulsating element and further material occurs directly in the spray head.

On the other hand, the variation of the wall thickness of the hose can be achieved by spraying the inner hose on a correspondingly shaped mold pipe and spraying the outer hose over it. The spraying can take place in a work process with a double spraying head or one after the other in line with separate extrusion devices.

Claims (1)

1. lä? Device for the production of a hose (2) consisting of at least two layers of different materials, the wall thickness of which in thinner intervals is thinner and thicker, which device comprises a spray head (4) with at least two different material supply lines , which leads to an outlet at the hose-forming point of the spray head, and means for effecting a periodically controllable change of the material supply to the hose-forming point, characterized in that said means consist of elastic pulsation rings (12, 13), which are arranged in grooves (10, 11) in the outer disc (9) of the spray head and / or its inner mandrel (8), means being provided for more or less pulsatingly expanding the pulsating rings (12f13) in a controlled manner by supplying gaseous or liquid media. \., .__._ ..