FR2490552A1 - METHOD AND DEVICE FOR APPLYING A LAYER OF RUBBER MATERIAL TO A BASE BODY OF OTHER QUALITY RUBBER MATERIAL - Google Patents

Abstract

THE APPLICATION OF A LAYER OR, IF APPROPRIATE, OF OTHER RUBBER ELEMENTS ON A BASIC RUBBER BODY IS MADE BY FIXING, BY EXTRUSION, USING A DEVICE IN WHICH IT IS PROVIDED, FOR BODY FORMATION BASIC, AN EXTRUDER 1 IN THE EXTRUSION HEAD 2 FROM WHICH OPEN LATERALLY AT LEAST ANOTHER EXTRUDER 4 FOR THE SECOND QUALITY OF RUBBER. THE UNION IS CARRIED OUT IN A SECTOR LIKE 3. THIS PROCESS APPLIES, AMONG OTHERS, TO THE MANUFACTURE OF TIRES.

Description

The present invention relates to a method for applying

  tion of at least one layer or other elements of a rubber material of a first quality determined on a base body made of rubber material of another quality, the use of this method for the application of the layer of

  contact on a tread profile for manufacturing

  tion of tires, as well as a device for carrying out

of the process.

  With the invention, it is in particular the applica-

  tion of the contact layer on a tread profile

  ment, this contact layer is usually referred to as a mattress or "undercushion". The application of this contact layer is still carried out today, all over the world, according to an archaic technique which has been practiced for decades. We can see the reason in the

  fact that the tire industry is extremely conservative

  trice. But we must also consider that new techniques

  which are not always suitable for the manufacture of pneumatic

ticks.

  The contact layer, i.e. the mattress, is applied

  as a bonding layer on the tire carcass, either by means of solvents or by the use of sheets

thin calendered.

  When operating with solvents, there are

  specific problems, such as the preparation phase

  separate to obtain the solution, the dangers to the

  solvents, the production of toxic vapors which require special ventilation systems, as well as problems related to drying, maintaining stocks, etc. In addition, this process is often accompanied by pollution that exceeds the average, cavities are created in the contact layer as a result of the formation of bubbles, depending on the kind of

  solvent it appears important tolerances as for the thickness-

  layer and the lateral guidance of the material is very imprecise.

  With the calendering process, there are difficulties

  similar cultures, in particular in that additional operations must be carried out in the reheating mill, that energy and space are wasted, that there is a poor bond between the contact layer and the profile

  tread due to oxidation and fouling

  air inclusions give rise to the formation

  tion of bubbles and even, where appropriate, to cavities.

  Ordinarily, this process is also accompanied by a waste of material, by the fact that calendering with certain qualities of rubber does not make it possible to descend

  below a predetermined minimum layer thickness.

  It is to eliminate these known problems that it is now-

  holding proposed, according to the invention, a new process in which the two qualities of rubbery material, namely that which is intended for the tread profile and that which is provided for the contact layer or mattress, are laminated separately and after the formation of the base body which is still in the hot state, the contact layer or, where appropriate, other profiled elements which are also still in the hot state, are applied by extrusion

on the base body.

  The application by extrusion of the additional rubbery material to the base body is preferably carried out under high pressure in the Plière of the extrusion head of the main extruder. If a contact layer is applied by extrusion, the thickness of this layer can be adjusted within certain limits by varying the arrival of

  material, i.e. by varying the capacity of the extruder

  god. The method of the invention is particularly suitable for the application of the contact layer, that is to say the

  mattress, on a tread profile for the manufacture-

tion of tires.

  The invention also relates to a device for carrying out the method, which device is characterized by a

  first extruder with an extrusion head for forming

  the base body is made of a first quality rubber material by at least one other extruder which is used for the plasticization of a second quality rubber material from which the contact layer or other profiled elements are manufactured, this or these other extruders opening laterally into the die part of the extrusion head of the first extruder, and finally by

  a sector for the formation of the composite profile, that is to say

  say of the final profile consisting of the base body and the layer or other profiled elements, applied by extrusion

on this body.

  The additional extruders are preferably arranged

  in such a way that they end up laterally in

  the extrusion head at an angle of 452 to 902.

  Thanks to the new process of the invention, according to which the contact layer is applied by extrusion to the rest

  of the profile, the drawbacks observed so far are eliminated.

  Many additional advantages are also derived therefrom, such as the following: The extruders can be supplied cold, which makes it possible to use plate mixing strips from the roller mixer, strips which can be stored without problems. ; The new process requires extremely simple handling. The whole process saves money

  energy, labor and raw materials.

  We achieve the best possible bond between the two qualities of matter, by the fact that it cannot form

  bubbles and, consequently, cavities.

  It is possible without difficulty to delimit with precision

  the contact layer or other elements fixed by extrusion. If a layer is applied by extrusion, layer thicknesses can be produced from

0.2 mm.

  There is no problem of environmental pollution, by the fact that the material can be covered without delay after it leaves the extrusion head, for example by means

  of a thin sheet of synthetic material.

  It should also be mentioned that the method for direct application by extrusion of the contact layer according to the invention can be carried out per se with any already existing tread manufacturing line:

  just add the additional extruder.

  Depending on the structure of the additional device, it is also possible to apply by extrusion, in place of a layer, other profiled elements, for example two angles.

  side (rods) in a second quality of rubber.

  The invention is explained below in a little more detail, using a device for carrying out the method of the invention, shown diagrammatically in the

  drawing, and using two possible composite profiles.

  Fig. 1 is a schematic graphical representation

  of a device for carrying out the method of the invention.

  Figs. 2 and 3 represent two composite profiles

  manufactured by the process according to the invention.

  fig. 1 of the drawings shows a device for

  direct manufacture of a tread profile, used

  used in the manufacture of tires, profile which is provided

  a contact layer, usually called a mattress or "under-

  cushion ". For this purpose we use a main extruder 1

  equipped with an extrusion head 2 and a usual die 3.

  The material for manufacturing the contact layer,

  ie from the mattress, arrives from a top extruder

  4, at an angle of 45 to 900. Under these conditions, the extruder 4 injects this material directly into the flat die 3 of the main extruder, which gives rise to a tread profile 5 provided with a contact layer. Fig. 2 of the drawings shows such a profile 5, which consists of the tread profile proper 6 and the layer 7 applied directly by extrusiot, constituting

the mattress.

  With the same device, it is also possible to fix by extrusion on the main profile 6, instead

  a layer 7, two side angles 8, 9 (see fig. 3).

  In the extrusion head, that is to say between the two extruders and the flat die, the rubber materials of different qualities are subjected to a high pressure, which gives rise, during the formation of the composite profile 5, to an exceptional quality of the union between the two materials; indeed, on the one hand, no bubble can form and, on the other hand, the delimitation or dimensioning of the two

  parts can be adjusted with exceptional precision.

  The main extruder works in the usual way.

  It can for example be supplied cold with a mixture

  plate from the roller mixer and the plastic material

  of the first quality reaches the extrusion head 2.

  The small additional extruder 4 is for example fed

  Tee also cold with a plate mixture from the roller mixer, the plasticized material being injected

  laterally in the flat die part 3 of the extruder head

  sion 2 of the main extruder, at an angle of 452 to 902.

  In the flat die 3 itself, which is constructed in such a way that it can be converted very quickly for the production of composite profiles of different shapes or of different layer thicknesses, the composite profile 5 is formed by the fact that the contact layer 7 or the angles

  8, 9 are fixed by extrusion to the base profile 6.

  Flat dies of this kind are known to the specialist.

  list, except for separate arrivals for second quality material. Appropriate dies can therefore be manufactured by the user's workshop or by any tool manufacturer. It is also possible, in a short time and by only a few operations, to clamp the junction pipe 12 of the extrusion head 13 of the small extruder 4 to the suitable part of the flat die 3

of the extrusion head 2.

  As soon as the tread profile, extruded in the main extruder 1, has started to form and comes out to the exact dimensions, the small extruder is put into service

  for the formation of the contact layer or the angles.

  Under these conditions, it is formed and fixed immediately by extrusion.

  sion, on the base profile, an impeccable contact layer with a flawless connection to the base profile, that is to say without bubbles and without cavities, in a constant position, precisely fixed, without the unwinding of the must

3 be constantly monitored.

  The particularly good bond results from the high pressure in the flat die during the union of the two qualities of material, as well as from a more favorable consistency of the materials and the absence of any oxidation or soiling (no residue of oil or dust from the air), because the union between the two materials takes place in the absolute shelter of the air. It goes without saying that an equally good connection is obtained between the base profile and possibly angles

fixed by extrusion.

  Within the framework of the process according to the invention or thanks to the device according to the invention, it is possible to vary within certain limits the thickness of the contact layer, that is to say the thickness of the mattress, changing speed

  of rotation on the small extruder. 4.

  It is obvious that thanks to the method according to the invention, the manufacture of tread profiles filled with contact layers is made much simpler and safer, compared to the previous methods. By the term "rubber" or * rubbery material "

  used in the foregoing description, it should be understood

  not only natural rubber, but also

  elastomeric synthetic materials.

Claims (5)

  1. Method for applying at least one layer or   very elements of a rubber material of a given quality on a base body made of rubber material of another quality, characterized in that the two qualities of rubber material are plasticized and, after the formation of the base body which is still in the hot state, said layer or the other elements, which are also still in the hot state, are applied by extrusion onto the basic body.   2. Method according to claim 1, characterized in that the application of the additional rubbery material on   the base body is made under high pressure.   Method according to claim 1 for applying an additional layer to the base body, characterized in that the thickness of the layer is adjusted by variation of the arrival of matter.   4. Use of the method according to claim 1 for the application of the contact layer on a strip profile   for the manufacture of tires.   5. Device for carrying out the process according to the claim   cation 1, characterized by a first extruder provided with an extrusion head for the formation of the base body in a rubbery material of a first quality, by at least one other extruder which serves for the plasticization of the rubbery material of a second quality which leads   laterally in the flat die part of the extrusion head   sion of the first extruder, and finally by a flat die   for the formation of the composite profile.   6. Device according to claim 5, characterized in that   that the extruder or additional extruders result in   feels laterally in the extrusion head at an angle from 452 to 909.