BEAD SEAL RING UNIT

Abstract: This invention is directed to the retreading of radial tires (10) by use of a bead sealing ring (24) unit that provides positive mechanical pressure for sealing the curing envelope (12) between the bead sealing ring unit and the bead area (16) of the tire by a radial force. In its relaxed or initial condition, the bead sealing ring unit has a diameter smaller than the bead diameter of the tire. The bead sealing ring unit is placed into sealing position and then expanded by a locking device secured to a metal band which is part of the bead sealing ring unit.

Description: BACKGROUND OF THE INVENTION This invention relates to a retreading system for curing radial constructed tires and refers particularly to a bead seal ring unit assembly used in retreading of radial tires in a precured tread system with a curing envelope, comprising a metal ring, mechanical locking means secured to said metal ring, said locking means having a retracted position and an expanded position, said radial tire having a bead member with an axial bead surface forming a circumference with a bead diameter, said metal ring having an initial diameter when said locking means is in its retracted position and an expanded diameter when in its expanded position. The invention relates also to a method of retreading a radial tire casing according to the preamble of claim 11. It is conventional in retreading to seal the curing envelope between the sidewall or side surface of the tire. Examples of sealing systems used in retreading systems are described in detail in US-Patents 2,966,936, 3,236,709, 3,802,978, 3,884,740, 3,895,985, 3,966,535, 4,129,474, 4,175,991, 4,242,169, 4,274,897 and 4,309,234. These references disclose various concepts of sealing the curing envelope between a mechanical structure and the sidewall or side surface of the tire casing. One known invention attempting to seal in the radial direction was disclosed in the United Kingdom. Application GB 2,032,858A corresponds to FR-A-2437928, upon which the preambles of claims 1 and 11 are based, and is one of two references which are considered in regard to the present invention. The other reference is FR-A-2319483. When a bead seal ring unit assembly as known from the aforesaid document and having the features as stated above in the beginning is used for sealing a curing envelope at the bead member of the radial tire the locking means are operated such that it leaves the retracted position and reaches the expanded position. In this position the metal ring is opened up along a certain distance close to the locking means. A gap occurs between both ends of the metal ring where no pressure is exerted to the axial bead surface and the envelope in this area. Furthermore this known bead seal unit assembly cannot compensate in accuracies of the diameter of the tires because the rigid metal ring provides only one definite sealing diameter in the expanded position of the locking means. SUMMARY OF THE INVENTION In the system of retreading according to the invention the curing envelope is sealed by expanding a rubber ring in the radial direction causing the seal to take place in the radial direction on the axial bead surface. This sealing system permits easy positioning of the bead seal ring unit because the diameter is smaller than the diameter of the tire's bead member when it is in the relaxed position, and in the expanded position there is a positive sealing action between the ring unit and the bead member of the tire securely sealing the curing envelope. The present invention provides a positive sealing method using a bead seal unit assembly to be located in a sealing position and expanded in the radial direction to provide positive sealing action along the axial surface of the tire bead member. This is accomplished by the bead seal unit assembly having a rubber ring which has a diameter smaller than the diameter of the tire bead and is expandable in the radial direction sealing the curing envelope between the rubber ring and the axial surface of the tire bead member. In the preferred embodiment there is a uniform and constant pressure provided by the rubber ring when sealing the curing envelope. In a preferred embodiment the positive sealing feature provides accommodation for variations in tire brands and constructions due to its positive mechanical expandability capabilities of the resilient surface of the rubber ring. In the preferred embodiment the rubber ring of the bead seal unit assembly has ridges which allow good sealing and gripping of the curing envelope to provide positive sealing. This permits testing of the curing envelope to assure that there are no leaks in the envelope before running a retreaded tire casing through the curing operation. In the preferred embodiment the bead seal unit assembly provides replaceability of the rubber rings when necessary in an easy and fast manner to provide for economic operation of the unit assembly by conserving cost and time for replacement and installation of a new rubber ring. In the preferred embodiment the bead seal unit assembly's locking mechanism assembly provides positive indication of sealing pressure by the unit assembly during the sealing operation. This gives visual notice to the operator if the rubber ring member of the bead seal unit assembly must be replaced. The locking mechanism assembly is designed to provide an over center locking feature. The locking mechanism latches in a manner to force positive sealing. When in its locked condition, if any additional forces act on it, these forces tend to move the locking mechanism into the locking position and not to the unlocked position, which would eliminate the sealing pressure. DETAILED DESCRIPTION The invention will be further understood from the following more detailed description taken with the drawings in which: Figure 1 is a side view of a standard radial tire; Figure 2 is a side view of a standard radial tire as viewed in Figure 1 that has been prepared for retreading and has a curing envelope in place, Figure 3 is a cross-section of the tire assembly as illustrated in Figure 2 taken along line 3-3 of Figure 2; Figure 4 is a cross-sectional view of a tire assembly similar to Figure 3 with the bead seal ring unit assemblies in place for curing, Figure 5 is an enlarged version of the bead area of the tire assembly shown in Figure 3, illustrating the relationship between the curing envelope and the bead member; Figure 6 is a view similar to Figure 5 showing the bead seal unit assembly in a sealing position before it had expanded into sealing contact; Figure 7 is a view similar to Figure 6 showing the bead seal unit assembly in the expanded condition with the rubber ring sealing the curing envelope between itself and the axial surface of the bead member; Figure 8 is a side elevation view of the tire assembly in condition for curing with the bead seal unit assemblies in place; Figure 9 is similar to Figure 8 showing the tire assembly ready for curing and being supported by a chain hanger system; Figure 10 is a cross-sectional view of a rubber ring showing its configuration; Figure 11 is similar to Figure 10 showing a metal band in position with the rubber ring when assembled; Figure 12 is a side view of a metal band without the locking mechanism or the rubber ring; Figure 13 is a perspective view of the bead seal ring unit assembly with the rubber ring and the locking mechanism in place; Figure 14 is an exploded perspective view of the locking mechanism in conjunction with the metal band; Figure 15 is a side sectional view of the locking mechanism in the locked or expanded position ; and Figure 16 is a side sectional view of a locking mechanism in the unlocked or retracted position. Referring to Figure 1, there is illustrated a radial tire generally by number 10. After the radial tire has been prepared for retreading, it is covered with a curing envelope 12, as shown in Figure 2. This is typical for many retreading operations with the possible exception that the curing envelope is more fully skirted or extends further toward the center of the tire. Referring generally to Figure 3, we have the radial tire 10 with a crown area 14 and bead member areas 16 and 18. The crown area 14 connects the bead areas 16 and 18 by sidewall sections 19 and 20. The curing envelope 12 extends around the tire 10 and past the bead areas 16 and 18. Referring to Figure 4, bead seal ring unit assemblies 24 have been placed in sealing position and were expanded mechanically in the radial direction to make positive sealing contacts with the bead areas 16 and 18. This view illustrates the principles of the present invention. Figure 13 shows the bead seal ring unit assembly 24 in partial cross-section showing the rubber ring 26 positioned around the metal band 27. Metal band 27, as shown in Figure 12, has overlapping ends to complete its circular embodiment. The inside end is identified as 28 and the outside end is identified as 29. The locking mechanism 30 is connected to the outside end 29 and the inside 28. The locking mechanism 30 is so constructed that the metal band 27 will be in its small diameter position when the locking mechanism 30 is in the unlocked position and in the expanded position when the locking mechanism 30 is in the locked position. This will be explained in detail below. Referring to Figure 5, we have an enlarged view of the bead area 16 which has a bead toe 32 and an axial bead surface 34 and a bead side surface 36. The envelope 12 extends alongside of the bead area and out of contact with it before the bead seal ring unit assemblies 24 are placed in sealing position. The curing envelope 12 is flexible but exhibits a stiff characteristic before being moved into sealing position. Referring to Figure 10, we have a cross-sectional view of the rubber ring 26. The rubber ring has a position flange 38 and a hook flange 40. The flanges 38 and 40 are connected by sealing surface 42 at their upper side. The sealing surface in the preferred embodiment, as shown in Figure 10, has a series of sealing ribs 44. At the lower surface, the flanges 38 and 40 are connected by a receiving groove 46. In the preferred embodiment, the receiving groove 46 has slanted side surfaces 47 so that they can receive the metal band 27 and hold it in place, as illustrated in Figure 11. When the rubber ring 26 is moved into sealing position, it will contact the curing envelope 12 and move it between the axial bead surface 34 and the sealing surface 42 of the rubber ring 26, als illustrated in Figure 6. At this time, the locking mechanism 30 is in the unlocked position and the metal band is in its smallest diameter position. The rubber ring 26 has a diameter smaller than the bead area diameter so that sealing contact is not made at this time. After the rubber ring 26 is in sealing position, the locking mechanism 30 is moved to the locked position, by expanding the diameter of the rubber ring 26 so that the curing envelope is sealed between the axial bead surface 34 and the sealing surface 42 of the rubber ring 26. The sealing ribs provide multiple gripping contacts so that the curing envelope is firmly held in place. The bead area 16 is rigid and a sufficient amount of pressure can be placed between the bead seal ring unit assembly 24, in the expanded position, and the bead member 16 so that the curing envelope 12 is securely sealed. This sealing is important to give proper cure and also it provides an opportunity for the retreading shop to inflate the curing envelope to ensure there is no leakage in the sealing or in the envelope before the expense of running the tire through the retreading operation. Figure 8 illustrates a radial tire after it has been enveloped and sealed and is ready to be placed into a curing chamber. When the bead seal ring unit assembly 24 is moved into sealing position and then expanded in sealing contact, there must be some flexibility in the system because various tire manufacturers have different configurations in reference to the bead area structure. The axial bead surface 34 is at a slight angle in reference to the axis of the tire. Typical angles would be 15° - 19°. As the rubber ring 26 is expanded, the hook flange 40 will wrap the end of the curing envelope 12 past the inside of the bead toe 32, as seen in Figure 6. The hook 40 prevents the rubber ring 26 from moving out past the bead toe 32 when in the expanded condition. The positioning flange 38 prevents the bead seal ring unit assembly 24 from extending past the bead side surface 36. The metal band 27 and the rubber ring 26 are positioned together to form the bead seal ring unit assembly. After a period of time, the rubber ring can lose its resilience, thus affecting its sealing capabilities, and will have to be replaced. The replacement is easily made by putting the metal band 27 in the unlocked position and removing the rubber ring 26 from the metal band. The resiliency of the rubber ring 26 can be monitored visually by the locking mechanism as will be explained in more detail below. Referring to Figure 14, there is an exploded view of the locking mechanism 30. The locking mechanism is connected to and operates the metal band 27. The locking mechanism 30 has four major elements. These include a band bracket 48, a slide bracket 50, a spring assembly 52, and a handle bracket 54. The band bracket 48 has two side plates 62 connected to a securing plate 61 and provides the connection to the inside end 28 of the metal band 27 for the locking mechanism 30. Near the back of the side plates 62, there are provided holes to receive a guide pin 64 and a spring pin 66. The bracket 48 is secured to the inside end 28 of the metal band 27 by connecting rivets 68. Slide bracket 50 has two slide plates 72 connected to support plate 71. The slide plates 72 are provided with undercuts 74, the function of which will be explained later. The side slide plates 72 are provided with guide slots 75. The guide pin 64 and spring pin 66 pass through the guide slots 75. The side plates 72 at their front end, are provided with openings to receive pivot pin 76, which extend across the support plate 71 and are secured in the slide plates 72. The slide bracket 50 is secured to the outside end 29 of the metal band 27 by connecting rivets 78. The side slide plates 72 are positioned outside the side plates 62 of the band bracket 48 when the unit is assembled. The undercuts 74 permit the slide bracket 50 to be moved in relation to the band bracket 48 without making contact with the inside end 28 of metal band 27 until in the fully unlocked position. Spring assembly 52 has a spring shaft member 81 with a yoke member 82 positioned on one end. The yoke member 82 has a yoke plate 84 that is connected to the shaft member 81 and connects to two side members 86. The two side members 86 have openings which receive the spring pin 66. On the other end of the shaft member 81, is a pivot block 88. The pivot block 88 has an opening permitting the shaft 81 to pass through the pivot block 88 and a control cap 90 is secured to the end of the shaft 81. On the side of the pivot block 88 are pivot studs 92. A spring 94 is positioned around the shaft 81 and applies force to the yoke plate 84 and to the pivot block 88. When under normal conditions, the spring will exert pressure between these members causing the control cap 90 to make contact with the pivot block 88. The handle bracket 54 has side plates 101 that are connected by connection plate 102. A handle arm 104 is secured to the connection plate 102 at one end and has a handle 105 at the other end. Above the connection plate 102, the handle arm has a control edge 107. The side plates 101 have control flanges 108 extending up from the side plates. The side plates 101 have openings identified as pivot stud openings 111 which receive the pivot studs 92. Near the front end of the side plates 101 are provided openings which permit the pivot pin 76 to pass through. Referring to Figure 16, we show the locking mechanism in the relaxed or unlocked position. The inside end 28 and the outside end 29 of the metal band 27 are overlapped at their maximum amount when the handle is fully moved into the unlocked position. This is a condition in which the locking mechanism 30 is in when the bead seal ring unit assembly 24 is placed into sealing position. Sealing contact is then secured by moving the handle in a counter-clockwise direction, as viewed in Figures 15 and 16, to its maximum locked position as illustrated in Figure 15. The handle bracket 54 is rotated about the pivot pin 76. This moves the pivot block 88 so that it tends to compress spring 94. This exerts force on the spring pin 66 moving to band bracket 48 away from the support plate 71 of the slide bracket 50, causing the metal band to expand its circumference and its diameter. After the rubber ring 26 makes sealing contact with the bead area and the resilience of the rubber ring 26 is compressed, additional force will be taken up by the pivot block 88 moving along the spring shaft member 81. This moves the control cap 90 away from contact with the pivot block 88, as viewed in Figure 15. In this position, the center line of pivot studs 92 is positioned below a line running from the center line of spring pin 66 and pivot pin 76. This provides an over-center self-locking feature. Any pressure applied to the metal ring 27 to compress it will force the locking mechanism 30 to be driven towards the locked position and away from the unlocked position. During operating conditions after a period of time, as mentioned above, the resiliency of the rubber ring will have been lost. At that time, a new rubber ring 26 should be put in place. The operator can identify when there is need for a new rubber ring 26 when the control cap 90 is not positioned away from the pivot block 88 when in the locked position. This is a visual inspection that can be easily made, preventing curing tires when proper sealing has not been engaged. Referring to Figures 8 and 9, Figure 8 shows the tire 10 after it has been prepared for retreading and the curing envelope 12 placed on the tire 10 and the bead seal ring unit assemblies 24 positioned in sealing contact with the bead member of the radial tire 10 and the curing envelope 12. It should be noted that the locking mechanisms 30 are lined up with one another. This is not a precise line-up, but should be close as an operator can easily position them. After the tire 10 is in this condition, it is ready to be cured. At this time, the tire 10 will be supported by a chain hanger 120. The chain hanger 120 is connected to a monorail system well-known in the art by the monorail rollers. Connecting rods hang down from the monorail rollers to a carrier member. At each end of the carrier member, support chains 122 are suspended and then connected to a support member 124. The support member 124 will act on the locking mechanism 30 between the control edge 107 and the control flanges 108. They will support the tire assembly on the upper edges of the side slide plates 72. The chain hanger 120 will provide support during the curing without causing any damage to the curing envelope 12 and the bead sealing units. This system maintains a constant pressure by means of the spring assembly in the locking mechanism 30. This also provides a system to accommodate variations in tire constructions by various tire manufacturers. The system provides a mechanism that is lightweight, easily handled by one individual, and reduces the time of placement and removal of the sealing devices while providing positive, effective sealing features. While illustrating one embodiment of the sealing surface, outer embodiments could be employed. For example, in Figure 13 we illustrate a smooth surface which would also be utilized in this type of sealing. The sealing ribs are preferred in our embodiment because they allow better sealing and gripping of the curing envelope.

Claims: Bead seal ring unit assembly used in retreading of radial tires (10) in a precured tread system with a curing envelope (12), comprising: a) a metal ring, b) mechanical locking means (30) secured to said metal ring, c) said locking means (30) having a retracted position and an expanded position, d) said radial tire (10) having a bead member (16, 18) with an axial bead surface (34) forming a circumference with a bead diameter, e) said metal ring having an initial diameter when said locking means (30) is in its retracted position and an expanded diameter when in its expanded position, characterized by that f) said metal ring is a metal band (27), g) said metal band (27) having overlapping inside and outside ends (28, 29), h) said inside and outside ends (28, 29) are moved towards each other when said metal band (27) is in the form of the initial diameter, i) said inside and outside ends (28, 29) are moved away from each other when said metal band (27) is in the form of the expanded diameter, and j) that an outer rubber ring (26) is mounted on said metal band (27). A bead seal ring unit assembly as in claim 1, including: a) a hook flange (40) on the inside of the rubber ring (26) extending around the rubber ring (26), b) a positioning flange (38) on the outside of the rubber ring (26) and extending around the rubber ring (26), c) a sealing surface (42) extending across the outer surface of the rubber ring (26) and connecting the said hook and positioning flanges, (40; 38) and d) said sealing surface (42) having an angle of 10° in reference to the center line of said ring unit (26; 27). A bead seal ring unit assembly as in claim 2, including: a) said sealing surface (42) having a series of sealing ribs (44). A bead seal ring unit assembly as in claim 3, including: a) a receiving groove (46) extending across the inner surface of said rubber ring (26) and connecting the said hook and positioning flanges (40; 38), b) said receiving groove (46) having slanted side surfaces (47), and c) said slanted side surfaces (47) of the groove secure said rubber ring (26) to said metal band.(27) A bead seal ring unit assembly as in claim 1, including: a) said locking means being a locking mechanism, (30) b) a band bracket (48) connecting said locking mechanism (30) to the inside end (28) of said metal band, (27) c) a slide bracket (50) connecting said locking mechanism (30) to the outside end (29) of said metal band, (27) d) said slide bracket (50) extends around said band bracket, (48) e) a spring assembly (52) rotatably connected at one end to said band bracket (48) and between the sides of said band and slide brackets, (48; 50) f) a handle bracket (54) rotatably connected at one end to said slide bracket, (50) g) a pivot block (88) rotatably connected to the sides of said handle bracket (54) having a predetermined position from said connection to said handle bracket, (54) h) said spring assembly (52) having a spring shaft member (81) with a yoke member (82) that connects to said band bracket (48) and at the other end said shaft (81) passes through said pivot block (88) and has a control cap (90) secured on its other end, and i) said spring assembly (52) having a spring (94) acting around the shaft (81) and applying force on the yoke member (82) and the pivot block (88). A bead seal ring unit assembly as in claim 5, including: a) said locking mechanism (30) having a sealing position when said metal band (27) is in the form of a sealing diameter, b) said sealing diameter is substantially equal to said bead diameter, and c) said sealing diameter is smaller than said expanded diameter. A bead seal ring unit assembly as in claim 6, including: a) said spring (94) being compressed between said yoke member (82) and said pivot block (88) when said ring unit (26; 27) is sealing said curing envelope (12) between said sealing surface (42) and said axial bead surface (34), and said metal band (27) is in the form of said sealing diameter, and b) said control cap (90) moves away from said pivot block (88) to disclose the sealing force of a predetermined spring. A bead seal ring unit assembly as in claim 7, including: a) a hook flange (40) on the inside of the rubber ring (26) extending around the rubber ring (26), b) a positioning flange (38) on the outside of the rubber ring (26) and extending around the rubber ring (26), c) a sealing surface (42) extending across the outer surface of the rubber ring (26) and connecting the said hook and positioning flanges (40; 38), and d) said sealing surface (42) having an angle of 10° in reference to the center line of said ring unit (26; 27). A bead seal ring-unit assembly as in claim 8, including: a) said sealing surface (42) having a series of sealing ribs (44). A bead seal ring unit assembly as in claim 9 including: a) a receiving groove (46) extending across the inner surface of said rubber ring (26) and connecting the said hook and positioning flanges (40; 38), b) said receiving groove (46) having slanted side surfaces (47), and c) said slanted side surfaces (47) of said groove (46) secure said rubber ring (26) to said metal band (27). Method of retreading a radial tire casing which includes the steps of preparing the tire casing for retreading, covering the prepared tire casing (10) with a curing envelope (12), applying an expandable bead seal ring unit (26; 27) for expanding the bead seal ring unit (26; 27) in the radial direction making positive sealing contact with the curing envelope (12) and the axial bead surface (34) of the bead member (16;18), characterized by: a) placing the bead seal ring unit (26; 27) against the curing envelope (12) which extends alongside of the bead area and out of contact with it before the bead seal ring unit (26;27) is placed in sealing position, b) moving the curing envelope (12) by pushing the bead seal ring unit (26;27) into alignment between an axial bead surface (34) of a tire bead member (16; 18) and a sealing surface (42) of the bead seal ring unit (26; 27), and c) then sealing the curing envelope (12) between the axial bead surface (34) and the sealing surface of the bead seal ring unit (26; 27) by expanding this unit. A method as in claim 11, comprising: a) compressing the spring (94) of said locking mechanism (30), and b) disclosing visually the positive force from the bead seal ring unit (26; 27) when in its sealing contact position.

Inventors: BREWER, DONALDEE, NIEDERGESES, THOMAS JOHN, SEILER, RONALD RAY
Applicants: BANDAG LICENSING CORPORATION
Application year: 1986
Main classification: B29D30
IPC codes: B29D30