EP0020385A1

EP0020385A1 - Removable tread belt and method of recapping same

Info

Publication number: EP0020385A1
Application number: EP79901035A
Authority: EP
Inventors: Charles E. Grawey
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1978-12-21
Filing date: 1980-07-01
Publication date: 1981-01-07
Also published as: IT1124996B; IT7927362A0; WO1980001262A1

Abstract

Dans une structure et une methode de rechappage d'une bande de roulement amovible (10) de pneus de vehicule (12), une nouvelle partie d'une bande de roulement (11) est appliquee sur la surface externe usinee (21') d'une bande de roulement usee (10). La nouvelle partie de la bande de roulement (11) peut-etre appliquee a la surface de la bande usinee au moyen d'une couche adhesive (23) et en appliquant ulterieurement une pression et/ou de la chaleur comme dans un four (24). La bande de roulement appliquee peut se presenter sous forme de sections separees (30) disposees en series annulaires en bout a bout (35) soit directement sur la surface revetue du produit adhesif usinee soit comme une configuration annulaire preformee. En variante, la bande de roulement de remplacement peut etre appliquee sur la surface revetue de l'adhe comme un corps annulaire (37). Le moulage de la configuration de la bande de roulement dans le corps (37) peut etre effectue en utilisant des platines de moulage (38, 39) qui peuvent etre chauffees de maniere appropriee pour effectuer le moulage de la bande de roulement desiree et la liaison du corps (37) sur la bande usee usinee (10). La partie de renforcement (16) de la bande usee (10) est reutilisee dans la bande retravaillee terminee.In a structure and method for retreading a removable tread (10) of vehicle tires (12), a new portion of a tread (11) is applied to the machined outer surface (21') of a worn tread (10). The new part of the tread (11) can be applied to the surface of the machined tread by means of an adhesive layer (23) and subsequently applying pressure and/or heat as in an oven (24 ). The applied tread may be in the form of separate sections (30) arranged in end-to-end annular series (35) either directly on the machined adhesive coated surface or as a preformed annular configuration. Alternatively, the replacement tread may be applied to the coated surface of the adhesive as an annular body (37). Molding of the tread pattern into the body (37) may be accomplished using molding plates (38, 39) which may be suitably heated to effect molding of the desired tread and bonding. of the body (37) on the machined worn strip (10). The reinforcing part (16) of the worn strip (10) is reused in the finished reworked strip.

Description

REMOVABLE TREAD BELT AND METHOD OF RECAPPING SAME

Technical Field This invention relates to retreading and more particularly to the recapping of a removable tread belt for a replaceable tread tire.

Background Art

It has been conventional to recap worn tires by utilizing a new removable belt to replace the worn tread on the tire carcass. It is also conventional to recap the carcass directly by bonding a new tread directly thereto.

Examples of prior art patents which illustrate conventional tire recapping methods include the Elmer J. Wasko United States Letters Patent 3,802,977, issued April 9, 1974, which teaches the retreading of the tire casing by utilization of a previously vulcanized tread which is cemented on the buffed, worn periphery of the casing. Wasko teaches the use of a specially configured bag to cover the precured tread so as to contain steam in heating and vulcanizing the adhesive to permanently cement the tread to the prepared tire casing.

Robert E. Sausaman, in United States Letters Patent 3,839,123, issued October 1, 1974, shows a prevulcanized annular tread section which is similarly applied to the buffed or otherwise prepared worn tire carcass or casing. Sausaman teaches the use of internal pressure in forcing the carcass against the annulus which is structurally adapted to tightly engage the worn carcass prior to the application of pressure thereto. A pressurized fluid heating medium is circulated within the casing so that the tread section is cured thereto in the bonding operation. In United States Letters Patent 3,868,284, issued February 25, 1975, Bernard E. Hogan, Sr. et al teach an apparatus and method of recapping worn tires with a precured tread arranged so as to maintain the sidewalls of the tire carcass relatively cool during the bonding operation. The heat is applied through the precured tread and a mold is utilized to introduce direct fluid pressure onto the outer surface of the tread to provide both pressure for the bonding operation and to provide a portion of the heat transfer means.

Jan-Eric Lennart Wulker, et al, in United States Letters Patent 4,053,265, issued October 11, 1977, show a mold for retreading pneumatic tires which is resilient and has an outer face of a normal unstretched diameter smaller than the outer diameter of the tire tread. A vulcanizable rubber band is provided around the tire carcass and the ring mold is first expanded and then fitted over the thusly applied band. The mold is then allowed to contract and is centered on the body while the tire is being rotated. The entire unit has been heated to a temperature sufficient to fuse the band and permit the ring mold to emboss the tread design onto the band which is concurrently vulcanized and bonded to the tire body.

Disclosure of Invention

The present invention comprehends an improved recapped removable tread belt manufacture.

More specifically, the invention comprehends the utilization of preformed tread sections in recapping a worn tread belt.

The recapped tread belt more specifically includes an annular belt base having an accurately circularly cylindrical machined outer surface, and a plurality of tread sections secured in end-to-end annular relationship to the belt base surface. Adhesive may be provided between the juxtaposed ends of the belt tread sections which may be cured concurrently with the curing of the belt sections to the worn removable tread belt. The machined outer surface..may be disposed closely outwardly of the reinforcing portion of the belt base, as desired.

The invention further comprehends the provision of such a recapped tread belt wherein the tread is applied in the form of a continuous strip tread section secured annularly about the belt base surface.

The invention further comprehends the improved method of reconstructing such removable tire belts having worn tread portions including the steps of arranging the worn belt in a cylindrical configuration with the worn tread portion thereof outermost, removing the worn tread portion to expose an outer cylindrical bonding surface, and bonding a replacement tread portion to the bonding surface. A layer of adhesive may be applied to the bonding surface which is set while the replacement tread portion is in contact therewith to effect the desired manufacture.

The manufacture may include the step of preforming a plurality of replacement tread portion sections and the bonding step may comprise a step of bonding the sections in end-to-end relationship, as well as to the bonding surface.

A pressure force may be applied to the sections to urge the sections forcibly in intimate association with the adhesive coating bonding surface.

The tread may be formed in an unmolded strip applied to the bonding surface concurrently with the bonding of the strip to the machined belt surface. The worn tread may be removed as by machining, buffing, trimming, etc., as desired. The worn belt may be mounted on a radially outwardly acting mandrel during the bonding step. The mandrel may be rotated during the bonding step to provide further improved manufacture of the recapped belt. Thus, the invention comprehends an improved structure for use in recapping a tire having a worn tread belt previously mounted on a tire carcass and an improved method of effecting the retread manufacture.

Brief Description of Drawings FIGURE 1 is a fragmentary transverse section of a replaceable tread tire;

FIGURE 1a is a perspective view of a tire illustrating a worn tread belt portion thereof;

FIGURE 2 is a fragmentary transverse section of a tire having a worn tread belt;

FIGURE 2a is a section taken substantially along the line 2a-2a of Figure 2;

FIGURE 3 is a fragmentary section illustrating the step of removing the worn portion of the tread belt; FIGURE 4 is a fragmentary transverse section illustrating the application of adhesive to the partially prepared tread belt;

FIGURE 5 is a fragmentary transverse section illustrating the provision of the replacement tread on the adhesively bonded, partially prepared tread belt;

FIGURE 6 is a fragmentary section illustrating the step of heating the assembly of Figure 5 to effect a bonding of the recapping tread to the tread belt;

FIGURE 7a is a fragmentary perspective view of one form of tread for use in the recapping of the tread belt;

FIGURE 7b is a fragmentary perspective view of another form of tread for such use;

FIGURE 7c is a fragmentary perspective view of still another form of tread for such use; FIGURE 8 is a perspective view of an annular arrangement of the recapping tread elemens suitable for installation on the partially prepared tread belt;

FIGURE 9 is a side elevation of a recapping belt in extended arrangement made up of preformed tread sections disposed in end-to-end relationship;

FIGURE 10 is a perspective view of the completed annular tread belt; and

FIGURE 11 is a fragmentary perspective view illustrating a step in forming the tread in situ on the reworked belt by means of tread-forming elements engaging the annular periphery thereof.

Best Mode for Carrying Out the Invention

In the illustrated embodiment, a structure for use in recapping a worn tread belt and method of forming the same are shown wherein a removable belt 10 is recapped with a new tread portion 11 so as to permit renewal of tread material in a worn replaceable tread tire, such as tire 12 shown in Figure la. One conventional form of tire includes an inner annular carcass portion 13, as seen in Figure 1, having a removable belt 10 mounted on an outer surface 14 thereof. The tread portion 15 of the belt may become worn, such as illustrated in Figure 2. Conventionally, when the belt has become so worn, the belt has been removed and replaced with a new belt. Heretofore, the worn belts have been scrapped.

The present invention comprehends an improved manufacture wherein the worn removable belt is recapped, thereby providing a substantial economy and improved utilization of natural resources by permitting the reuse of a substantial part of the worn removable belt including the reinforcing portion 16 as a base, as shown in Figure 3.

As shown in Figure 2, in carrying out the manufacture of the present invention, the worn belt 10 may be placed on a suitable mandrel 18 during the reworking operation after having been removed from the tire carcass 13 in the conventional manner well known to those skilled in the art. Mandrel 18 may comprise an annular mandrel supporting the belt circumferentially, as illustrated in

Figure 2, so as to permit facilitated handling of the worn belt in the recapping operation.

As shown in Figures 2 and 2a, the mandrel may be provided with a grooved outer surface 19 for receiving the radially inwardly projecting annular ribs 20 of the replaceable belt for facilitated handling of the removable belt in the recapping operation.

As shown in Figure 3, the worn belt 10 may have the outer worn portion 21 thereof removed by machining or similar operation to define an accurate annular outer surface 21' for receiving the new tread portion 11. In the illustrated embodiment, the worn tread portion 21 is removed by a grinding operation, such as by application of grind wheel 22 to the outer surface portion. In the illustrated embodiment of Figure 4, a layer of adhesive 23 is applied to the machined outer surface 21' of the removable belt, and as shown in Figure 5, the new tread portions 11 may be secured to the surface 21' by the adhesive 23. The adhesive may comprise a rubber adhesive.

As shown in Figure 6, the completion of the bonding of the new tread portion to the reworked worn tread belt may be effected by heating the assembly on the mandrel 18 in a suitable apparatus, such as oven 24, defining a heating chamber 25 which may be heated by any suitable means, such as electric heating coil 26. Chamber 25 may, if desired, be placed under a positive pressure so as to firmly urge the new tread portions against the adhesive 23 and, thus, assure a positive bond to the reworked belt surface 21'. Referring to Figures 7a, 7b and 7c, different tread configurations may be utilized as desired in the recapping of the belt. Thus, as shown in Figure 7a, a first tread configuration 27 may be utilized, as shown in Figure 7b, a different tread configuration 28 may be utilized, and as shown in Figure 7c, a still different tread configuration 29 may be utilized, it being understood that the tread configurations illustrated are exemplary only and that the invention comprehends the utilization of any desired tread configuration in recapping the belt.

The tread portion may be formed of a plurality of segmental sections, such as sections 30. The invention comprehends the selective bonding of the tread sections" to the prepared worn belt portion by either placing the individual sections on the adhesive coated surface

21' individually, or by firstly forming them into an annular arrangement and applying the annulus to the adhesive coated annular surface 21'. Thus, as shown in Figure 9, the individual sections may be laid out in a series, having the confronting ends 31 and 32 secured as by suitable adhesive. As illustrated in Figure 9, the complete replacement tread length may be laid out in a rectilinear series which, as shown in Figure 8, may then be brought to an annular configuration with the opposite ends 33 and 34 of the series being joined adhesively to complete the annular arrangement 35.

The completed annular retreaded belt 36 is illustrated in Figure 10 showing the secured assembly of the new tread portion 11 to the removable belt 10. The reworked belt 36 may now be utilized as a replacement for the original worn belt of the tire 12 by the mounting thereof to the original tire carcass 13 in the conventional manner. Referring now to Figure 11, a modified method of providing the new tread on the belt is shown to include the step of providing the tread configuration in an annular body 37 mounted about the machined, reworked belt portion. Annular body 37 may comprise an uncured rubber tread portion which may have the tread configuration molded therein concurrently with the bonding of the material to the machined belt portion by means of molding platens 38 and 39 movable against the moldable body 37 in diametrically opposed directions, as shown in Figure 11. Thus, the formation of the desired tread configuration and the securing of the new tread to the reworked worn belt portion may be concurrently effected for further facilitated economy and simplicity in manufacture. As will be obvious to those skilled in the art, the tread body 37 may be comprised of conventional unvulcanized rubber or any other suitable tread material, as desired. As shown in Figure 11, the interior of the machined worn belt portion may be supported on a suitable mandrel 40 during the tread forming and bonding operation.

Thus, the invention comprehends the removal of the worn tread of a removable tire belt by suitable means, such as buffing or machining, and the replacement of the worn tread portion with a new tread portion. The replacement may be effected selectively by providing a plurality of individual tread sections about the circumference of the reworked belt outer surface, by the placement of an annular molded tread element thereabout, or by forming the tread on a tread body placed about the reworked belt portion by concurrently forming the tread configuration and bonding the tread means to the reworked belt portion. The bonding and forming operations may be performed in a suitable autoclave or by suitable heating and pressure-applying means as are conventionally utilized in the tire-forming art.

By utilizing the removable belt base portion, a substantial saving in the provision of new tread material for the belt is effected as not only is the requirement for rubber material minimized, but also the wire reinforcing portion. of the belt may be reutilized. Industrial Applicability

The invention may be utilized in conjunction with all forms of vehicle tires and the like utilizing removable belts. By minimizing the amount of new material necessary to effect the recapping of the worn tread belt, a substantial economy and energy saving is obtained. The invention has been found to be highly efficacious in connection with the recapping of removable tread belts for earthworking vehicle tires which are of relatively large size and wherein the retreading thereof by replacement of the removable belts is very expensive. The use of the present invention realizes a substantial economy in particular in connection with tread belts for such large size vehicle tires. Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims. The foregoing disclosure of specific embodiments is illustrative of the broad inventive concepts comprehended by the invention.

Claims

1. Recapping structure for use in recapping a worn removable tread belt tire (12), said recapping structure comprising: an annular worn belt (10) constructed to be installed on the tire (12) provided with a base (16) having an accurately circularly cylindrical machined outer surface (21'); and a replacement tread (11) secured in annular relationship about said belt base surface to define a retreaded tread belt (36).

2. The recapping structure of Claim 1 wherein said surface (21') is provided with a layer of adhesive (23) defining means for providing a bond of said replacement tread (11) to said surface.

3. The recapping structure of Claim 1 wherein said replacement tread (11) is defined by a plurality of sections (30) in end-to-end relationship and adhesive (23) is provided between juxtaposed ends (31,32) of the tread sections, said adhesive defining means providing for a cured bond between said tread section ends.

4. The recapping structure of Claim 1 wherein said belt base includes an annular reinforcing portion (16) and said machined outer surface (21') is disposed closely outwardly of said reinforcing portion.

5. Recapping structure for use in recapping a worn removable tread belt tire (12), said recapping structure comprising: an annular worn belt (10) constructed to be installed on the tire (12) provided with a base (16) having an accurately circularly cylindrical machined outer surface (21'); and a continuous strip tread section (35) secured annularly about said belt base surface (21').

6. The"recapping structure of Claim 5 wherein said surface (21') is provided with a layer of adhesive (23) providing for a cured bond of said continuous strip tread section (35) to said surface (21').

7. A method of reconstructing removable tire belts (10) having a worn tread portion (21) comprising the steps of: arranging the worn belt (10) in an annular configuration with the worn tread portion (21) thereof outermost;, removing the worn tread portion to expose an outer cylindrical bonding surface (21'); and bonding a replacement tread portion (11) to said bonding surface (21').

8. The method of reconstructing removable tire belts of Claim 7 further including the steps of applying a layer of adhesive (23) to said bonding surface (21') and setting the adhesive with the replacement tread portion (11) in contact therewith to effect said bonding.

9. The method of reconstructing removable tire belts of Claim 7 further including the step of preforming a plurality of replacement tread portion sections (30) and said bonding step comprises a step of bonding said sections (30) in end-to-end relationship to said bonding surface (21').

10. The method of reconstructing removable tire belts of Claim 7 further including the step of preforming a plurality of replacement tread portion sections (30) and said bonding step comprises a step of bonding said sections (30) to each other in end-to-end relationship and to said bonding surface (21').

11. The method of reconstructing removable tire belts of Claim 7 further including the step of preforming a plurality of replacement tread portion sections (30). and said bonding step comprises a step of bonding said sections (30) in end-to-end relationship to said bonding surface (21') while applying a pressure force to said sections urging the sections forcibly into intimate association with the adhesive coated bonding surface.

12. The method of reconstructing removable tire belts of Claim 7 wherein the strip (37) of curable tread-forming material is applied to said bonding surface (21') and the bonding step comprises a step of curing the strip while applying a tread configuration mold (37,38) thereto to bond the strip to said bonding surface and concurrently form a desired outer replacement tread portion configuration (27,28,29, etc.).

13. The method of reconstructing removable tire belts of Claim 7 further including the steps of applying a layer of curable adhesive (23) to said bonding surface (21'), applying a strip of curable tread-forming material (37) to the adhesive-coated bonding surface (21'), and concurrently curing the adhesive and the strip while applying a tread configuration mold (37,38) thereto to bond the strip to said bonding surface and concurrently form a desired outer replacement tread portion configuration (27,28,29, 35c).

14. The method of reconstructing removable tire belts of Claim 7 wherein the step of removing the worn tread portion (21) comprises a step of machining the belt.

15. The method of reconstructing removable tire belts of Claim 14 wherein said machining step comprises a step of buffing the worn tread (21) from the belt (10).

16. The method of reconstructing removable tire belts of Claim 14 wherein said machining step comprises a step of trimming the worn tread (21) from the belt (10).

17. The method of reconstructing removable tire belts of Claim 7 wherein the step of arranging the belt in a cylindrical configuration comprises the step of removing the worn belt (10) from the tire carcass (13) and mounting the worn belt (10) on a radially outwardly expandable mandrel (18) prior to the worn tread removing step, said mandrel (18) being urged outwardly during said bonding step.

18. The method of reconstructing removable tire belts of Claim 7 wherein the step of arranging the belt in a cylindrical configuration comprises the step of removing the worn belt (10) from the tire carcass (13), and mounting the worn belt (10) on a radially outwardly expandable rotatable mandrel (18) prior to the worn tread removing step, said mandrel being rotated during said worn tread removing step.