REMOVABLE TREAD BELT AND METHOD OF RECAPPING SAME

Abstract: Structure and method for recapping removable tread belt (10) vehicle tires (12) wherein a new tread portion (11) is applied to a machined outer surface (21') of a worn tread belt (10). The new tread portion (11) may be applied to the machined belt surface by means of an adhesive layer (23) and subsequent application of 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 adhesively coated surface or in the form of a preformed annular configuration. Alternatively, the replacement tread may be applied to the adhesively bonded surface as an annular body (37). The molding of the tread configuration in the body (37) may be effected by use of molding platens (38, 39) which may be suitably heated to effect the molding of the desired tread and the bonding of the body (37) to the machined worn belt (10). The reinforcing portion (16) of the worn belt (10) is reused in the completed reworked belt (36).

Description: - - 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 -che 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 pre- vulcanized 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 circu¬ lated within the casing so that the tread section is cured thereto in the bonding operation. In United Sta ' tes 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 opera— tion and to provide a portion of the heat transfer means. Jan-Eric Lennar 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 in¬ cludes an annular belt base having an accurately circu¬ larly cylindrical machined outer surface, and a plural¬ ity of tread sections secured in end-to-end annular relationship to the belt base surface. O PI Adhesive may be provided between the juxta¬ posed 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 ap— plied 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 arrang- ing the worn belt in a cylindrical configuration with • the worn tread portion thereof outermost, removing the worn tread portion to expose an outer cylindrical bond¬ ing surface, and bonding a replacement tread portion to the bonding surface. A layer of adhesive may be applied to the bond¬ ing 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 pre- forming a plurality of replacement tread portion sec¬ tions 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 sec- tions to urge the sections forcibly in intimate asso¬ ciation 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. OMPI -4- The worn belt may be mounted on a radially out¬ wardly acting mandrel during the bonding step. The man¬ drel 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 tixe; FIGURE la is a perspective view of a tire illus trating 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 alon the line 2a-2a of Piguxe 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; OMPI 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 sec¬ tions 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. Convention¬ ally, 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 util- ization 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 manu- facture of the present invention, the worn belt 10 may be placed on a suitable mandrel 18 during the reworking oper¬ ation 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 sup- porting 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 surf ce 19 for receiving the radially inwardly projecting annular ribs 20 of the re¬ placeable belt for facilitated handling of the removable belt in the recapping operation. As shown in " Figure 3, the wprn belt 10 may have the outer worn portion 21 thereof removed by machining or similar operation to define an accurate annular outer sur¬ face 21' for receiving the new tread portion 11. In the illustrated embodiment, the worn tread portion 21 is remove 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 sur¬ face 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 rub- ber 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, de- fining a heating chamber 25 which may be heated by any suit able 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 ad¬ hesive 23 and, thus, assure a positive bond to the reworked belt surface 21*. O PI 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 util¬ ized, 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 inven¬ tion comprehends the selective bonding of the tread sec¬ tions" 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 annu¬ lar 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, hav- ing the confronting ends 31 and 32 secured as by suitable adhesive. As illustrated in Figure 9, the complete re¬ placement 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 illus¬ trated in Figure 10 showing the secured assembly of the new tread portion 11 to theremovable belt 10. The reworked belt 36 may now be utilized as a replacement for the orig¬ inal 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 por¬ tion which may have the tread configuration molded there¬ in 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 for¬ mation 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 sup- ported 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 replace¬ ment 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 portio by concurrently forming the tread configuration and bond¬ ing the tread means to the reworked belt portion. The bond ing 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 reinforc¬ ing portion.of the belt may be reutilized. ■ 5MEA^~ O PI 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 con¬ nection 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 par¬ ticular in connection with tread belts for such large size vehicle tires. Other aspects, objects and advantages of this invention can be obtained f om 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. OMPI

Claims: Clai s 1. Recapping structure for use in recapping a worn removable tread belt tire (12) , said recapping struc¬ ture comprising: an annular worn belt (10) constructed to be installed on the tire (12) provided with a base (16) hav¬ ing an accurately circularly cylindrical machined outer surface (21'); and a replacement tread (11) secured in annular relation¬ ship 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 replace¬ ment 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 struc¬ ture 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 -- SLEAl OMPI IPO outer surface (21'); and a continuous strip tread section (35) secured annu- larly 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 bel (10) in an annular configur¬ ation 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 por¬ tion (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 asso¬ ciation 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 configura¬ tion (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 C37) to the adhesive-coated bonding surface (21'), and concurrently curing the adhesive and the strip while ap¬ plying 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. Th 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. OMPI 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 re- moving the worn belt (10) from the tire carcass (13) and mounting the worn belt (10) on a radially " outwardly expand¬ able mandrel (18) prior to the worn tread removing step, said mandrel (18) being -urged outwardly during said bond¬ ing 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 re¬ moving the worn belt (10) from the tire carcass (13) , and mounting the worn belt (10) on a radially outwardly expand- able rotatable mandrel (18) prior to the worn tread removing step, said mandrel being rotated during said worn tread removing step. OMPI WIPO

Inventors: GRAWEY C
Applicants: CATERPILLAR TRACTOR CO, GRAWEY C
Application year: 1978
Main classification: B29H17
IPC codes: B29D30