MXPA00011293A - A method and apparatus for forming tire components - Google Patents

Abstract

A method of forminga tire component (10) from an unvulcanized elastomeric strip having two or more laterally adjacent distinct compounds is provided. The method includes the step of feeding a first compound into a pair of calender rollers (350, 352), wherein one of the rollers (350) has a forming depression (356). The first compound is formed in a first portion of the forming depression (356). Next, a second compound is fed into the pair of calender rollers (350, 352). The second compound is formed in a second portion of the forming depression (356). The second compound is laterally separated from the first compound by one or more separating means (320) for separating the first and second compounds.

Description

METHOD AND APPARATUS FOR FORMING RIM COMPONENTS TECHNICAL FIELD This invention relates to methods and apparatuses for forming elastomeric components and more specifically said invention relates to methods and apparatuses for forming rim components. BACKGROUND OF THE INVENTION Many components of a rim are produced in extruders. The primary function of an extruder is to heat, plasticize and form mixed rubber to obtain a desired profile. The extruder consists of a feed box, a screw inside a cylinder, and a head that has a die plate. Some extruders also have inserts or flow channels that guide the rubber from the screw to the die opening. The die opening has a shape similar to the desired profile of the rubber extrudate. The process flow of rubber through an extruder begins with the entry of rubber into fibers or pieces in the feed box. The rubber is pulled by the rotating screw in the empty area between the screw and the cylinder. The rubber is transported along the screw and compressed by the rotation of the screw towards the head. When the hydraulic pressure in the rubber is sufficiently high, the rubber is pushed through the die opening which forms an extruded product having approximately the profile of the die opening. In order to facilitate a smooth flow of rubber through the die opening, a "removal band" is used to remove the stretched product from the die. Generally, the removal band stretches the extruded product between 2% and 10%. This situation causes stresses in the extruded rubber product and creates a tendency to shrink. Shrinkage can result in failures of unwanted uniformities in finished tires. The "die-swollen" phenomenon occurs when the extruded product exits the die and expands in a larger cross-sectional area. All extruders have a certain percentage of die swelling that can contribute to faults of unwanted uniformities in the tires. An extruded product can be composed of more than one rubber compound. Extruded products with two different compounds are made with duplex extruders that have two cylinders, and each cylinder has a screw inside. The two cylinders are usually fixed on a common head that holds a die. Inserts or splicing bars and flow channels are formed. This interface is known as the "division". Extruded products of three compounds are made with a triple extruder that has three cylinders with a screw inside each cylinder. Similarly, extruded products of four compounds are made with a quadruple extruder that has four cylinders and screws. Extruded products can be made with any number of compounds using extruders that have the corresponding number of cylinders and screws. Using complex flow channels it is possible to make more than one extruded product simultaneously from the same die plate with several die openings. It is common to extrude 2, 3 or 4 products extruded simultaneously. Some extruders have one or two driven rollers that form part or all of the die opening. This type of extruder is known as roller nose or double roller extruder. In order to extrude a uniform rubber part, the extruded product must be sufficiently resistant to high temperatures so as not to stretch excessively (less than 10%) or to not break. SUMMARY OF THE INVENTION This invention relates to forming a strip of unvulcanized rubber with a desired profile using the "hot formed" technology previously disclosed in a US Patent Application No. 08 / 854,070, now US Patent No. 5,762,740 . The disclosure to which we refer covers the forming and preassembly of frame components of a rim normally formed by an extruder or control calender. This invention goes beyond the disclosure to which we referred to include various rubber compounds formed in the same hot forming calender station and the ability to form and pre-assemble a full range of viscosities and adhesive qualities of rubber polymer. This new technology allows liquid rubbers to be formed and pre-tested on other components. This technology allows one liquid or semi-liquid rubber to be applied to another in a very similar way to the application of roller paint. This new technology makes it possible to use very soft and / or "sticky" rubber that has not previously been processed with extruders or calenders. The use of "plows" 320 or adjustable dividers between soft calender rollers and contour 350, 352 allows the divisions or interfaces between the compounds to be placed precisely in the desired location. The flexibility of the hot forming system allows optimal processing conditions for different types of rubber polymers. As reference to Figure 2, the use of this technology to form the tire rolling component 10A can be used as an example. Although the overall cross-sectional profile of Figure 2 is symmetrical, the profiles of individual compounds are asymmetric.

There is no limitation as to the number and as to the shape of zones of different possible compounds with this technology. The dimensional control for each zone of compound as well as the total component is significantly better than in the case of known extrusion technology. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a perspective view of one embodiment of the apparatus 200 of this invention. Figure 2 is a cross-sectional view of a rim race 10a that can be made by the apparatus 200 of this invention. Figure 3 is a cross-sectional view of a rim sidewall 10B that can be made by the apparatus 200 of this invention. Figure 4 is a top view of a calender 302, a portion of the calender 302 shown in cross section. Figure 5 is a perspective view of the calender 302 showing the forming depressions 356 on the roller 350. DEFINITIONS "Axial" and "axially" refers to lines or directions that are parallel to the axis of rotation of the rim. "frame" means a non-vulcanized rolled product of sheet rim material and other rim components cut to a suitable length for splicing or already spliced into a cylindrical or toroidal shape.Additional components may be added to the frame before its vulcanization to create the molded rim "cover" refers to rim framework and associated rim components excluding rolling. "Circumference" refers to lines or directions that extend along the perimeter of the surface of the annular tread. perpendicular to the axial direction "Equatorial plane (EP)" refers to the plane perpendicular to the axis of rotation of the rim and passing through the center of its rolling. "Lateral" refers to an axial direction. "Radial" and "Radially" refers to directions radially towards the axis of rotation of the rim or away from said axis of rotation. "Rim with Radial Layers" refers to a tire a circumferentially restricted pneumatic wherein the fold cords extending from flange to flange are placed at rope angles between 65 ° and 90 ° relative to the equatorial plane of the rim. "Lateral Wall" refers to the part of the rim between the tread and the rim. "Tread" refers to a rubber or elastomeric component that, when attached to the rim shell, includes the portion of the rim that comes into contact with the road when the rim is normally inflated and under a normal load. DETAILED DESCRIPTION OF THE PREFERRED MODALITY This invention relates to forming a strip of unvulcanized rubber with a desired profile using a "hot forming" technology previously disclosed in a United States of America Patent Application entitled, A METED AND APPARATUS FOR BUILDING TO LAMINATE AND FORMING A CARCASS SUBASSEMBLY FOR A TIRE, and which received the serial number 08 / 854,070. The patent application to which we refer covers the forming and pre-assembly of frame components of a rim normally formed through an extruder or contour calender. This invention goes far beyond the disclosure to which we referred to include many rubber compounds forming in the same hot forming calender station and the ability to form and pre-assemble a full range of adhesive qualities and viscosities of rubber polymers . This new technology allows the formation and pre-assembly of liquid rubbers on other components. This technology allows a liquid or semi-liquid rubber to be painted on another rubber very similar to the application of roller painting. This new technology makes possible the use of very soft and / or "sticky" rubbers, previously improvable with extruders or calenders of contour.

With reference to Figure 1, an exemplary use of the apparatus 200 for forming elastomeric strips 10 suitable for use in a pneumatic rim is shown. The apparatus 200 and alternative methods of using the apparatus 200 are disclosed after a commentary as to the elastomeric strips 10. In one embodiment of the invention, illustrated in Figure 2, the elastomeric strip 10A is a rim bearing (which receives the reference number 10A) formed of several components. Although the overall cross-sectional profile of Figure 2 is symmetrical, the profiles of individual compounds are asymmetric. It is obviously not required for this invention that the individual composite profiles be asymmetric. Compound A would be a highly adhesive base compound with low hysteresis. Compound B would be a compound of good heat dissipation capacity, low hysteresis suitable for the inner side of the rim. Compound C would be specially designed for the center of the footprint. Compound D would be especially suitable for the outer side of the rim. Compounds E and F would be to restrict abrasion for tire tread wear and for better traction on wet and dry roads. In summary, these compounds A, B, C, D, E and F can be formed in various sizes, shapes, colors and can have viscosities, adhesive qualities and other descent characteristics as desired. This offers great design flexibility for tire designers. In another embodiment of the invention, as shown in Figure 3, the elastomeric strip 10 is a rim sidewall (which receives the reference number 10B) also formed of several compounds. Again these various compounds 1, 2, 3, 4, 5, 6 can be formed in various sizes, shapes and colors, adhesive qualities and other characteristics as desired. It will be noted that all compounds are formed into components that are strip of material of substantially the same length. Each compound, illustrated in Figures 2-3, is located precisely laterally relative to another. The elastomeric strip (s) 10 when manufactured (n) as shown in Figure 1 can be made into continuous rolls 210. The elastomeric strip (s) is / are after, in its pre-assembled state, stored in large rolls 21Q that when it is sent to a tire manufacturing station, it is cut into sections of a precise length. The large roll 210, as shown, is driven by a motor 209 to facilitate the winding of the elastomeric strip 10 on the roll 210. Having described the elastomeric strip 10, attention is now paid to Figure 1 for a description of the single apparatus 200. used to form the elastomeric strip 10. The apparatus 200 includes at least one calender assembly station 300 for applying an elastomeric strip 10 on a transport device 204 which may include a conveyor belt 207. Alternatively, the calender assembly 300 can apply an elastomeric strip 10 on an elastomeric strip 10 previously formed already applied on the transport means 204. In this way a rim component (eg the rolling 10A illustrated in Figure 2) can be formed with vertically stacked strips. It will be noted that each vertical strip 10 (which may include several different laterally adjacent compounds) requires a separate calender assembly station 300. Thus, the rolling 10A of the rim 2 requires three separate 300 calender assembly stations. 10 would form the bas4e, made of composite A. The second vertical strip or row (including the three compounds B, C, D) can all be formed in a second calender assembly station 300. Similarly, the upper strip (including the compounds E and F) can be formed in a third of calender assembly station 300. The transport means 204 can have two large rotating drums 204 fixed on a rigid frame 180. The conveyor belt 207 which is preferably non-extensible and preferably made of stainless steel material is wrapped on the drums 205. The output end of the apparatus 200 has a rotating drum 205 driven or by a variable speed motor 205A. The transport means 204 is moved at a predetermined speed beyond the calender assembly station (s) 300. Below the conveyor 207 there is a device 600 for laterally positioning and guiding the conveyor belt 207. The calender assembly station 300 is used either alone or with another calender assembly station (s) 300 to form the elastomeric strip (s) 10 as indicated above. Strips 10, used as rim components, each have a predetermined cross section formed, as shown in Figure 5, by at least one forming depression 356 machined in one of the calender rolls 350, 352. With reference to Figure 4 , a detailed view of a calender assembly 302 is shown. Each calender assembly 302 is functionally the same as the next or the adjacent one with the exception of the pair of calender rolls 350, 352. Each calender assembly 302 includes a means of supply 360 for supplying] (or feeding) processed elastomeric material 25 to the throttle 354 of the calender rolls 350, 352, the throttle 354 being located between the two calender rolls. The administration means 360 as shown is an extruder 360. Each calender assembly 300 includes at least one extruder 360 but could include several extruders 360. For example, to form the middle row of rolling 10a illustrated in FIG. they could employ three extruders 360, one extruder feeding the compound A, the second extruder feeding the compound B and the third extruder feeding the compound C. On the other hand, a single extruder 360 could feed a single calender assembly with two streams of material. conveyed to two different shaped depressions 356 in one of the calender rolls 350, 352. It will be noted that the use of extruders 360 without the need for an extrusion head means that the elastomeric strips 10 can be formed at temperatures much lower than those used in current technology. In order for the extruder 360 to operate automatically, a device 362 is provided to detect and measure the flow of extruded material 25 to the calenders. Referring again to Figure 1, the calender assembly 302 includes lateral positioning means 320 (which are also known as separation means 320) for laterally positioning (and separating when more than one compound is employed) the processed elastomeric material. at a predetermined lateral location above the calender rolls 350, 352. The profile 320 is known as plows 320. At least one pair of plows 320 is laterally positioned at a predetermined location radially above the pair of calender rolls 350, 352 Each plow 320 has two rigid members 324 with a suitable contour to adjust its position above and between the two rollers. The rigid plow member 324 may be positioned laterally adjacent a side end of a forming depression 356 located in one or both of the calender rolls 350, 352. It should be noted, however, that the plows 320 may also be placed in the middle of a forming depression 356. In this case, when a first compound is fed from one side of the plow 320 and a second compound is fed from the first plow 320, as the first compound and the second compound pass through the throttle 354 and beyond the plow 320, the first compound and the second compound are joined laterally before being removed from the rolls. Thus, the use of plows 320, that is to say (or adjustable dividers) between smooth and contoured rolls 350, 352, allows the precise placement of the divisions or interfaces between compounds in the desired location. The plows 320 also secure and provide lateral support while preventing the formation of an overflow of calendered material and its adhesion to the conveying means 204. The lateral position of the component forming depressions 356 are precisely located relative to the belt. conveyor 207. This ensures that each component as formed is aligned and fixed relative to the transport means 204 and in relation to any previously formed and fixed component. The precise lateral positioning ensures that each component is properly positioned and allows for minimum material variation while also reducing the relative size of each component due to tolerance variations that occurred in the prior art assembly method. As shown in figure 4Each calender assembly 302 has two calender rollers 350, 352, one roller being the transfer roller 350, the other being the follower roller 352. Each calender assembly 302 includes a means 304 for supporting the rollers. Each calender assembly 302 has at least one motor, preferably two motors 340, 342. The flexibility of the hot forming method described above allows obtaining optimum processing conditions for different types of rubber polymers. There is no limitation regarding the number or shape of probes of different compounds possible with this technology. The dimensional control for each compound zone as well as the total component is significantly better than with the known extrusion technology. The invention has been described with reference to preferred embodiments. Evidently others can devise modifications and alterations to see and understand this specification. All these modifications and alterations, insofar as they are within the scope of the appended claims or their equivalents, belong to said invention.

Claims (1)

1. CLAIMS A method for forming a rim component, the method is characterized by the steps of: providing a first calender station (300) including a supply means (36) for supplying processed elastomeric material (25), a first pair of calender rollers (350, 352) having an associated throttle (354) therebetween where one of the pair of calender rollers (352) includes at least one forming depression (356), and a first lateral positioning means (320 ) to laterally position the processed elastomeric material at a predetermined lateral location above the pair of calender rolls; using the supply means for feeding a first stream of elastomeric material processed in the constriction where the first stream is formed in a first portion of the forming depression; and using the supply drive to feed a second stream of elastomeric material processed in the throttling, where the second stream is formed in the second portion of the forming depression, the second stream is laterally separated from the first stream by the first medium of lateral positioning; and, where as the first stream and the second stream pass through the constriction beyond the lateral positioning means, the first stream and the second stream are joined laterally before being removed from the roll having the depression formed therein to obtain a first formed strip (10) of elastomeric material. The method according to claim 1, further characterized by the steps of: providing a second current calender assembly station below the first assembly station, the second assembly station includes a second supply means for supplying processed elastomeric material, a second pair of calender rollers having an associated throttling therebetween where one of the second pair of calender rollers includes at least one forming depression, and a second lateral positioning means for laterally positioning the processed elastomeric material at a lateral location predetermined above the second pair of calender rollers; and transporting the first formed strip of the first calender assembly station to the second calender assembly station; forming a second strip formed of elastomeric material in the second assembly station; and apply the second layer on the first layer. The method according to claim 1, wherein the rim component is a rim rolling (10A). A method of forming at least two rim bearings (10A) from unvulcanized elastomeric material characterized by the steps of: feeding a first stream of rolling compound (25) onto a pair of calender rolls (350 , 352) one of the rollers (352) has a first forming depression and a second forming depression (356), the first running compound stream is formed in the first forming depression; and, feeding a second stream of rolling compound in the pair of calender rolls, the second stream of rolling compound is formed in the second forming depression, the second stream formed of rolling compound is laterally separated from the first formed stream of rolling compound by one or several separation means (320) for separating the first stream of rolling compound from the second stream of rolling compound. The method according to claim 4, wherein the first stream and the second stream of rolling compound are supplied to a single supply means (360). A rim component formed by the method according to claim 1, wherein the first stream and the second stream are different elastomeric compounds and wherein the first stream forms a first portion of the component and the second stream forms a second portion of the component. The rim component according to claim 6, wherein the component has a transverse profile and at least one of the first portion or second portion has an asymmetric transverse profile. An apparatus (200) for simultaneously forming at least two rim bearings (10A) from unvulcanized elastomeric material, the apparatus is characterized by: a first and a second calender roller (350, 352) having a throttle ( 354), one of the rollers (352) has a first forming depression and a second forming depression (356) to form a first race and a second race; a supply means (360) for selectively simultaneously supplying a first stream and a second stream of unvulcanized elastomeric material (25) to the first calender roll and second calender roll; a lateral positioning means (320) for positioning the first stream and the second stream of the unvulcanized elastomer material at predetermined lateral locations above the first calender roll and second calender roll such that the first stream and the second stream of the material elastomeric uncured particles penetrate into the first forming depression and the second forming depression, respectively; and, a transport means (204) for transporting the first roll and the second roll away from the first roll and second roll.