Flexible mold segment for forming a tire with a sipe element having protrusions

Abstract

A mold segment (10) for forming a tire is provided. The mold segment has a tread element (14) having a first end and a second end. A first side (20) and a second side (22) are oppositely disposed in a width direction, and a bottom and a top are oppositely disposed in a height direction. The tread element has a protrusion (30) extending from the first side. There is a mold segment base (32) made of a material more flexible than the material forming the tread element (14). The mold segment base receives the tread element such that the bottom of the tread element is located inside the mold segment base and the top of the tread element is located outside the mold segment base. The mold segment base defines a cavity (34), and the protrusion (30) is located inside the cavity (34). The mold segment (10) is for forming a production mold segment (68) that will ultimately mold a green tire into a cured tire (12).

Description

Technical Field

[0001] The present invention generally relates to a flexible die segment for forming a tire. More specifically, the present application relates to a flexible die segment characterized by a siping element having protrusions for insertion into mating cavities of the flexible die segment. Background Art

[0002] The production of a tire includes the step of placing an uncured tire within a mold, at which time heat and pressure are applied to the uncured tire in order to change its state to a cured condition. During the curing process, the uncured tire is placed inside a metal mold that surrounds the exterior of the uncured tire. When the uncured tire is within the mold, an inflatable rubber bladder is positioned within the uncured tire and inflated to apply pressure to the inner surface of the uncured tire. The pressure applied by the inflatable bladder forces the uncured tire against the mold such that the uncured tire is subjected to pressure. Heat may be applied simultaneously, and the combination of heat and pressure applied for a specific period of time effectuates the curing process. The cured tire may then be removed from the mold and transported downstream for further processing.

[0003] The inflatable bladder forces the crown portion of the tire against accessories of the mold when inflated and applying force, and the accessories include a series of features for forming tire grooves, siping, and tread blocks so as to form the tread design of the tire. The accessories may be made of two or more multi-sections arranged in a circle, and these production die segments are used to form the architecture of the tread. In order to form the siping of the tread, a series of siping sections are present in the production die segment. Additional siping elements may be included to form siping that may be V-shaped, Y-shaped, or alternative shapes and may extend in the longitudinal direction, transverse direction, or both longitudinal and transverse directions.

[0004] To form the production die segment, a casting process employs a plaster / stucco casting segment that includes a siping element. To form the plaster casting segment, a flexible casting segment is used and the siping element is inserted into the flexible casting segment, and the siping element is ultimately transferred to the production die segment. The flexible casting segment may be referred to as a flexible die segment or simply as a die segment. The siping element may be made of steel or other metal, while the flexible casting segment base is made of rubber or some other more flexible material. To form the flexible casting segment, a master / positive segment is formed, which may have preliminary siping forming elements therein, and the negative image of the preliminary siping forming elements is transferred to the flexible casting segment. In the flexible casting segment, the siping element may need to be forced into the flexible base of the flexible casting segment, and doing so may result in difficulty in precisely aligning the siping element with other features of the flexible base. Due to the flexibility of the flexible base, the positioning of the siping element may change during subsequent stages of the development of the production die.

[0005] To maintain the positioning of the siping elements within the flexible mold, it is known to incorporate locking features between the siping elements that constrain one siping element relative to another contacting siping element. This connection between two steel siping elements occurs at the ends of the two siping elements or, in other configurations, between the end of one siping element and the face of a second siping element. Although the connection of multiple siping elements fixes their positions relative to one another to some extent, this connection does not constrain the positioning of the siping elements to the flexible base itself, and the siping elements can still move out of position relative to the flexible base. Thus, there remains room for change and improvement in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The full and enabling disclosure of the invention, including its best mode, for one of ordinary skill in the art is set forth more particularly in the remainder of the specification, which makes reference to the accompanying drawings, in which:

[0007] Figure 1 is a perspective view of a tire having siping adjacent to the grooves.

[0008] Figure 2 is a perspective view of the main mold base.

[0009] Figure 3 is a perspective view of the flexible mold segment.

[0010] Figure 4 is a perspective view of the plaster casting segment.

[0011] Figure 5 is an exploded perspective view of the mold.

[0012] Figure 6 is a top view of the accessory.

[0013] Figure 7 is a side view of a siping element having a protrusion with a length greater than the height.

[0014] Figure 8 is Figure 7 a top view of the siping element.

[0015] Figure 9 is a perspective view of the mold segment base.

[0016] Figure 10 is along Figure 3 a cross-sectional view taken along line 10-10 of

[0017] Figure 11 is a side view of a siping element having a protrusion with a height greater than the length.

[0018] Figure 12 is Figure 11 a top view of a siping element.

[0019] Figure 13 is a perspective view of the siping element.

[0020] Figure 14 is a top cross-sectional view of a die segment base configured to receive Figure 13 the siping element.

[0021] Figure 15 is a perspective view of the die segment base and the siping element with a flanged protrusion.

[0022] Figure 16 is a top cross-sectional view of the siping element inserted into Figure 15 the die segment base.

[0023] Figure 17 is a perspective view of a flexible die segment with a siping element disposed adjacent a bead of the die segment base.

[0024] Figure 18 is a cross-sectional view taken along line Figure 17 18 - 18.

[0025] Figure 19 is a perspective view of a portion of a tire finally formed by Figure 17 and Figure 18 the flexible die segment.

[0026] Figure 20 is a perspective view of a master die base with preliminary siping having preliminary siping protrusions for forming cavities in the flexible die segment.

[0027] The repeated use of reference numerals in this specification and the drawings is intended to represent the same or similar features or elements of the present invention. Detailed Description

[0028] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention and is not meant as a limitation of the invention. For example, features shown or described as part of one embodiment can be used with another embodiment to yield a third embodiment. The invention is intended to include these and other modifications and variations.

[0029] Provided is a die section 10 having a siping element 14 that includes a first side 20 and a second side 22 and has a protrusion 30 on the first side 20. The die section 10 is a flexible die section 10 for forming a production die section 68 that will ultimately mold a green tire into a cured tire 12. The die section 10 also includes a die section base 32 made of a more flexible material such as polysulfide castable mold rubber than the siping element 14. The die section base 32 includes a cavity 34 that is within the die section base 32 and is large enough to receive the protrusion 30. The siping element 14 is pushed into the softer material of the die section base 32 in a desired location, and in doing so, the protrusion 30 is received within the cavity 34. This reception enhances the stability and positioning of the siping element 14 within the die section base 32, which ultimately results in a more known and accurate positioning of the siping patterns 74, 82 formed by the siping element 14 when the tire 12 cures. The size and shape of the cavity 34 are set such that when the protrusion 30 is received within the cavity 34, the cavity provides some holding force to the protrusion 30.

[0030] Reference Figure 1 , shows the tire 12 in perspective, which has a central axis 72 that serves as the axis of rotation of the tire 12. The central axis 72 extends through the center of the tire 12 and is aligned in the axial direction 76. The radial direction 78 of the tire 12 extends outward from the central axis 72 and is perpendicular to the central axis 72. The tire 12 also has a circumferential direction 80 that extends around the circumference of the tire 12 and encircles the central axis 72. The circumferential direction 80 can be at any distance from the central axis 72 in the radial direction 78 of the tire 12 and does not need to be located only at the tread 84 or the outermost portion of the tire 12 in the radial direction 78.

[0031] The tire 12 has a tread 84 that has different tire architectures such as tread blocks, grooves, sipes, and ribs. Other tire 12 architectures of the illustrated tread 84 include V-shaped sipes 74 that are located in two of three zones formed by a shoulder edge of the tread 84 and two grooves 90 that extend completely around the tire 12 in the circumferential direction 80. Circumferential sipes 82 extend completely around the tire 12 in the circumferential direction 80 and are adjacent to and slightly spaced from the circumferential grooves 90. In some embodiments, the spacing can be 1 millimeter, 2 millimeters, 3 millimeters, 4 millimeters, or 5 to 10 millimeters in the axial direction 76 and can be consistent along the entire length of the circumferential sipes 82 and circumferential grooves 90 in the circumferential direction 80, or can vary at different locations along their lengths. The sipes 74, 82 are defined as grooves in the tread 84 that have a width of 2 millimeters or less at the tread surface. Thus, the grooves in the tread 84 can be grooves having a width greater than 2 millimeters. The widths of the sipes 74, 82 can be measured at the surface of the tread 84 when the tread 84 is new and unworn, because in some instances, the teardrop portions (if any) of the sipes 74, 82 can actually be greater than 2 millimeters. The sipes 74, 82 and grooves 90 can be of any shape and extend in any direction, such as angled, curved, or serrated. The sipes 74 are V-shaped because they have two legs that are angled with respect to each other and a vertex at the point where the two legs intersect. A pair of sidewalls extends from the crown of the tire 12 toward the center of the radial direction 78 on either side of the axial direction 76. Depending on the geometry of the tire 12, some features of the tread 84, such as the lateral sipes 74 and grooves, can also extend into the sidewalls.

[0032] To cure the tire 12, the uncured tire 12 is placed into a mold 92 having a production mold segment 68. To construct the protrusion mold segment 68, a number of initial and intermediate mold segments need to be produced first. First, the designer can create an initial design of the tire 12 in a computer program and then transfer the design to the master mold 52 via a CNC machining operation. The master mold 52 is in Figure 2is shown and includes a main mold base 54, which is milled from a block of material and is a positive image of the tire 12 to be produced. As a milled component, the main mold base 54 is made of a hard, non-flexible material, but not so hard that it cannot be cut and shaped during the milling process. To form smaller features, such as tread grooves 74, 82, in the tire 12, preliminary tread grooves 56 are set into the main mold base 54. The preliminary tread grooves 56 are made of metal and can be placed by the user by hand into cavities in the main mold base 54. The preliminary tread grooves 56 are placed in the areas where the tread grooves 74, 82 are ultimately desired to be located in the tire 12. Due to the rigidity of the main mold base 54, the positions where the preliminary tread grooves 56 are inserted are fixed and at known locations with little variation.

[0033] After the main mold 52 is completed, the next step in the production process is to form the flexible mold segment 10, an example of which is referenced Figure 3 shown. Here, a polysulfide castable mold rubber can be poured over the main mold 52 and allowed to harden. It should be understood that this is just one material, and other materials are possible when forming the flexible mold segment 10. Silastene can be one of the materials that make up the flexible mold segment 10. Once fully hardened, the user can peel the polysulfide castable mold rubber from the main mold 52 to expose the negative image of the tire 12 in the flexible mold segment 10. The preliminary tread grooves 56 are not transferred into the flexible mold segment 10 but remain within the main mold 52, but the preliminary tread grooves 56 form complementary voids at the locations where the tread grooves 74, 82 are desired in the flexible mold segment 10. The flexible mold segment 10 has a mold segment base 32, which is made of polysulfide castable mold rubber and shows the negative image of the tread 84. Tread groove elements 14 are provided, which are made of steel or aluminum or other materials harder than the material that makes up the mold segment base 32. Then, the user will take these different tread groove elements 14 (one of which is shown in Figure 3 ), and push them into the softer material of the mold segment base 32. The mold segment base 32 will have voids in which the tread groove elements 14 are located, but the dimensions of the tread groove elements 14 can be slightly larger than these voids, such that the tread groove elements 14 are forced into and held within the softer material of the mold segment base 32 because the material will push back and act to hold the tread groove elements 14. However, this type of placement can cause the tread groove elements 14 to move away from their desired positions, or subsequent steps in the mold forming process can cause these tread groove elements 14 to move or change orientation, thereby reducing the quality of the ultimately molded desired tire 14.

[0034] The flexible mold segment 10 is used to manufacture, for example, Figure 4The plaster casting section 66 shown. Plaster can be poured onto the flexible mold section 10, or the flexible mold section can be brought into contact with the plaster in other ways. Once the plaster has solidified and hardened, the plaster casting section 66 forms a positive image of the tire 12 being produced. Then, the user can peel the flexible mold section 10 from the plaster casting section 66 to expose the mold section as shown in Figure 4 the mold section. The tread elements 14 are embedded and held within the plaster casting section 66, and the peeling of the mold section base 32 causes the mold section base 32 to become disengaged from the different tread elements 14, thereby causing the tread elements 14 to transfer from the flexible mold section 10 to the plaster casting section 66. The plaster casting section 66 has different features imparted into the production mold section 68, such as grooves, ribs, and shoulder features. To form the production mold section 68, hot liquid aluminum is poured onto the plaster casting section 66, and then the hot liquid aluminum hardens and takes on the features of the plaster casting section 66, and exposed parts such as the tread elements 14 are embedded into the production mold section 68. The hot liquid aluminum thus forms the production mold section base 70 into which the tread elements 14 are installed. The plaster is cut or machined away in order to remove it from the production mold section 68 while leaving the tread elements 14 within the production mold section 68. In this regard, the tread elements 14 transfer from the plaster casting section 66 to the production mold section base 70 of the production mold section 68.

[0035] Figure 5A mold 92 for curing a tire 12 is shown. The tire 12 made of uncured rubber is placed in the mold 92 and cured via heat and pressure applied by the mold 92. The mold 92 can be constructed in a variety of ways. In the illustrated embodiment, the mold 92 includes an attachment 94 having a series of production mold segments 68 that engage the tire 12 to form the tread 84 of the tire 12. The mold 92 also includes a top mold zone 86 and a bottom mold zone 88 that engage the sidewalls of the tire 12 and form the sidewall portions. In other arrangements, additional top mold zones 86 and bottom mold zones 88 may be included, and thus a plurality of other components may be present in the mold 92 for forming the tire 12. The green / unmolded tire 12 can be placed inside the attachment 94, and the top mold zone 86 and the bottom mold zone 88 can be moved into engagement with the attachment 94. An inflatable bladder is placed through one of the zones 86, 88 and placed inside the tire 12 and inflated so as to press the tire 12 against the tread production elements of the production mold segments 68 (which can be, for example, the sipe elements 14 that form the sipes 74 and 82) and against the interiors of the top mold zone 86 and the bottom mold zone 88. Heating elements can be located within the different production mold segments 68, or they can be heated in other ways to transfer heat into the tire 12 within the mold 92. In this way, the mold 92 is capable of applying heat and pressure to the tire 12 within the mold 92. Although described as all being movable, it is possible that some of the production mold segments 68 are immovable while other production mold segments are actually movable to open and close the mold 92. The production mold segments 68 can be movable because they move relative to the ground on which the mold 92 rests.

[0036] The bladder can be inflated with air, steam, liquid, nitrogen, or any other fluid to cause it to expand, thereby forcing the tire 12 against the tread-forming portion and the sidewall-forming portion of the mold 92. After applying sufficient heat and pressure to the tire 12 for a sufficient length of time, the bladder can be deflated, and the top mold zone 86 and / or the bottom mold zone 88 can be moved away from the attachment 94 to allow the cured tire 12 to be removed for further processing.

[0037] Reference Figure 6, the accessory 94 of the mold 92 is made of a plurality of production mold segments 68 that extend 360 degrees around the axis. The production mold segments 68 can be joined to each other, or there can be small spaces between the production mold segments 68. In some arrangements, the production mold segments 68 can move radially towards the central axis during curing to further apply pressure to the tire 12. In other instances, the production mold segments 68 are stationary and do not move radially. The production mold segments 68 can be the same size as each other, or the sizes can be different from each other. Although eight production mold segments 68 are shown, it should be understood that in other arrangements, the accessory 94 can include any number of production mold segments 68. For example, in other types of molds 92, the accessory 94 can include 9 to 12 production mold segments 68. Thus, the production mold segments 68 engage the tire 12 during formation and include different tread elements 14 that are used to form the treads 74, 82 of the tire 12 when molded by the mold 92.

[0038] The present invention mainly relates to the flexible mold segment 10, which is a stage in the production process of manufacturing the production mold 92 that actually molds the tire 12. Thus, the flexible mold segment 10 is not the production mold 92, and the mold segment base 32 is not the production mold segment base 70 and thus does not engage the tire 12 at any point. As described above, the flexible mold segment 10 includes a series of tread elements 14 that are ultimately transferred to the production mold 92 and thus become part of the production mold 92. An example of the tread element 14 is referenced in Figure 7 and Figure 8is shown. The lug element 14 has a first end 16 and an oppositely disposed second end 18 that are spaced apart from each other in the longitudinal direction 42 of the lug element 14. The ends 14, 16 can be the terminals of the lug element 14 such that these portions of the lug element 14 are at the two extremes in the longitudinal direction 42. The ends 14, 16 are shown as being parallel to each other, but need not be parallel in other arrangements. The length of the lug element 14 in the longitudinal direction 42 is the longest breadth of the lug element 14. The lug element 14 has a bottom 26 and an oppositely disposed top 28 in the height direction 44 of the lug element 14. The height direction 44 is parallel to the longitudinal direction 42, and the height of the lug element 14 can be the distance from the bottom 26 to the top 28, and the distance of the height of the lug element 14 is less than the length of the lug element 14 in the longitudinal direction 42. The bottom 26 is the portion of the lug element 14 that is inserted into and covered by the mold segment base 32, while the top 28 is exposed. The bottom 26 is shown as having a pair of triangular-shaped recesses that have lips that facilitate gripping the rubber of the mold segment base when being pushed into the mold segment base 32. The width direction 24 of the lug element 14 is perpendicular to both the longitudinal direction 42 and the height direction 44, and the lug element 14 is shorter in the width direction 24 than it is in the longitudinal direction 42 or the height direction 44. The lug element 14 has a first side 20 and an oppositely disposed second side 22, and the sides 20, 22 are separated from each other in the width direction 24. The sides 20, 22 are shown as being planar as illustrated, but need not be planar in other embodiments as they can be angled, wavy, curved, or of different shapes.

[0039] The lug element 14 further includes a series of protrusions 30 extending from the first side 20 in the width direction 24. The protrusions 30 may extend in the width direction 24 a length that is longer than the distance between the sides 20, 22 in the width direction 24. The protrusions 30 are identical to each other in terms of their shape and size and are spaced the same amount from successive protrusions 30. The protrusions 30 extend a greater distance in the length direction 42 than they do in the height direction 44. Although the protrusions 30 may be located at any position along the height of the first side 20 in the height direction 44, they are located at a point along the lower half of the first side 20 in the height direction 44 such that they are closer to the bottom 26 than to the top 28 in the height direction 44. In some embodiments, the protrusions 30 may be made of the same material as the remainder of the lug element 14 and may be integrally formed with the remainder of the lug element 14, but not in other embodiments. The lug element 14 may be formed by casting, additive manufacturing, or by any other process. Additive manufacturing allows the protrusions 30 to be formed on the first side 20 of the lug element 14. The additive manufacturing process may have limitations regarding the amount of undercut available in the formation of the protrusions 30 and the lug element 14. A laser trimming process may also be employed to form the lug element 14 with the protrusions 30.

[0040] Figure 9is a perspective view of a die segment base 32 of the flexible die segment 10 as previously discussed in accordance with various exemplary embodiments, the flexible die segment being made of polysulfide castable die rubber or Silastic. The die segment base 32 has an upper surface 38 and an oppositely disposed lower surface 40 in a die segment base height direction 36. The die segment base 32 is a negative image of the tire 12 and has features of the upper surface 38 that are negative images of elements of the tire 12. For example, a bead 60 is present on the upper surface 38 and will be used in subsequent steps to form a groove 90 for the tread 84. The die segment base 32 includes a series of cavities 34 that are located within the die segment base 32 such that they are spaced from both the upper surface 38 and the lower surface 40 in the die segment base height direction 36. The shape of the cavities 34 is complementary to the shape of the protrusions 30 and, in some instances, may be identical to the shape of the protrusions 30. The cavities 34 may have the same dimensions as the protrusions 30. In other embodiments, the dimensions of the cavities 34 are sized to be less than or greater than the protrusions 30. The amount by which the cavities 34 are spaced from each other is the same as that of the protrusions 30 such that they can receive the corresponding protrusions 30 therein. A recess 33 is present and is a void in the die segment base 32. The recess 33 may open at the upper surface 38 and may communicate with all of the cavities 34 that receive a particular siping element 14 of the protrusions 30. The recess 33 may be present to aid in forming the cavities 34 within the die segment base 32. The recess 33 may also be present to aid a user in determining where the siping elements 14 should be inserted into the die segment base 32. It should be understood that in other embodiments, the recess 33 need not be present and the cavities 34 may be hidden from view when the user initially receives the die segment base 32.

[0041] To assemble the flexible die segment 10, a user will take a siping element 14 and push it into the die segment base 32, and this assembly is referenced Figure 3 and Figure 10 shown, Figure 10 is along Figure 3Cross-sectional view taken along line 10-10. The user can insert the tread element 14 into the recess 33 such that the bottom 26 is pushed into the interior of the die segment base 32. The depth of the recess 33 in the die segment base height direction 36 can be shorter than the desired depth into which the tread element 14 is to be inserted into the flexible die segment 10. In these instances, the tread element 14 can be forced into the softer material of the die segment base 32, and the bottom 26 is pushed in the die segment base height direction 36 to a level below the lowest point of the recess 33. The gripping force of the die segment base 32 can hold the tread element 14 therein. The flexible die segment 10 includes protrusions 30 that are located within the cavities 34 when the tread element 14 is inserted. As shown, some of the cavities in the cavity 34 are within the bead 60 of the die segment base 32. This interaction serves to further hold the tread element 14 within the die segment base 32 and maintain the position of the tread element 14 at the desired site without displacement during the forming process. The material of the die segment base 32 can be directly above and below the protrusions 30 in the die segment base height direction 36, and if the top and bottom of the protrusions 30 are joined by this material, the material can serve to squeeze the protrusions 30 and hold the protrusions and the rest of the tread element 14 in place. The depth of the cavity in the width direction 24 can be the same as the extent of the protrusions 30 in the width direction 24, or can be longer. Even if the cavity 34 is larger in size than the protrusions 30, the placement of the protrusions within the cavity will still serve to hold the tread element 14 in place because movement of the protrusions 30 will cause them to impact the material of the die segment base 32 that defines the cavity 34 and stop further movement.

[0042] When the protrusions 30 are located within the recess 33 and are larger than the recess 33, the placement of the tread element 14 within the die segment base 32 can cause the recess 33 to open. The flexibility of the material forming the die segment base 32 allows this deformation. Once the protrusions 30 are aligned with the cavities 34, the material will spring back into place to relieve this deformation of the recess 33. Although shown as having the same shape as the protrusions 30, in other embodiments, the cavities 34 can have a different shape than the protrusions 30. The cavity 34 is shown as rectangular, but can be of a different shape in other embodiments. The placement of the protrusions 30 within the cavities 34 causes the tread element 14 to interlock with the die segment base 32. It should be understood that the protrusions 30 and the tread element 14 can be shaped differently according to different exemplary embodiments and need not have a rectangular and planar shape in other types of flexible die segments 10.

[0043] Figure 11 and Figure 12 An alternative embodiment of the tread element 14 is shown, where the protrusions 30 are with Figure 7 and Figure 8The embodiments are different. Here, the length of the protrusions 30 in the height direction 44 is longer than their length in the length direction 42. The extent of the protrusions 30 in the width direction 24 is longer than the length between the first side 20 and the second side 22 in the width direction 24. Although all the protrusions 30 have the same size and shape, this need not be the case in other embodiments, in which different protrusions among the protrusions 30 of the lug element 14 have different sizes and shapes from other protrusions among the protrusions 30. Further, although shown as only present on the first side 20 and not on the second side 22, in other embodiments, one or more of the protrusions 30 may be present on the first side 20 while one or more of the protrusions 30 are on the second side 22. Thus, there are various configurations of the protrusions 30 on the lug element 14. Based on the establishment of the protrusions 30 on the lug element 14, the cavities 34 are constructed in the die segment base 32 in a suitable manner.

[0044] Another exemplary embodiment of the lug element 14 and the die segment base 32 are shown respectively in Figure 13 and Figure 14 In Figure 13 the lug element 14 is curved along the length direction 42 and thus has a first side 20 that has both a curved portion and a planar portion. The protrusions 30 are all likewise positioned along the first side 20 and there are no protrusions on the second side 22. The protrusions 30 have a narrow portion that engages the first side 20 and extends from the first side in the width direction 24. A semi-circular section is positioned at the end of the narrow portion, which represents the end of the protrusion 30 and is the portion of the protrusion 30 that is furthest from the first side 20 in the width direction 24. The die segment base 32 has cavities 34 that are shaped to be complementary to the shape of the protrusions 30 and are oriented within the die segment base 32 to match the positioning of the protrusions 30 when the protrusions 30 are inserted into the die segment base. The narrow portion and the semi-circular portion function to lock the protrusions 30 into the cavities 34, where there will also be material between the semi-circular portion and the first side 20 in addition to material existing above and below in the height direction 44. To insert the protrusions 30 into the cavities 34, sufficient force is applied to push the semi-circular portion through the narrow portion of the cavities 34. Depressions 33 are present to assist the user in positioning the lug element 14, and the depressions 33 communicate with all the cavities 34.

[0045] Figure 15 and Figure 16 show another exemplary embodiment of the flexible die segment 10, in which the protrusions 30 include additional locking features to further attach the protrusions to the flexible die segment base 32. Figure 15 shows the lug element 14 detached from the die segment base 32 but to be inserted into the die segment base 32, whileFigure 16 is a top cross-sectional view of die segment 10, where the tread element 14 is actually inserted into die segment base 32 such that the protrusion 30 is disposed within cavity 34. The protrusion 30 extends from a first side 20 in a width direction 24 and is shaped to define a lip 46 at one end in a longitudinal direction. An empty space 48 is defined from the lip 46 to the first side 20 in the width direction 24. In a complementary configuration, the cavity 34 has a lip receiving portion 50 shaped and sized to receive the lip 46. The lip receiving portion 50 is in turn formed by an incision-shaped protrusion of the material forming the die segment base 32. The cavity 34 is also shaped and sized to receive the remainder of the protrusion 30, and when the protrusion 30 is inserted into the cavity 34, the lip 46 is disposed within the lip receiving portion 50. The material forming the die segment base 32 is bendable to allow insertion of the lip 46, and in some instances, the tread element 14 can slide in a length direction 42 such that the lip 46 can be inserted into the lip receiving portion 50 without deforming or significantly deforming the material forming the die segment base 32. When inserted, the lip 46 has the material of the die segment base 32 between it and the first side 20, which serves to further lock the protrusion 30 within the cavity 34 and in turn hold the tread element 14 in place within the die segment base 32.

[0046] Figure 17 and Figure 18Shows another exemplary embodiment of the flexible die segment 10, where the siping element 14 is provided adjacent to the bead 60 of the die segment base 32. The bead 60 is provided to form a groove 90 in the tread 84, and the groove 90 can be a circumferential groove that extends completely around the tire 12 by 360 degrees in the circumferential direction 80, or a groove that is not a circumferential groove, and / or a groove that does not extend completely around the tire 12 by 369 degrees. The siping element 14 is placed in a position in the die segment base 32 to be parallel to the bead 60. In this regard, the bead 60 has a bead sidewall 64 that extends over at least a portion of the bead length in the length direction 42. The siping element 14 engages the bead sidewall 64, and in some embodiments, the cavity 34 can extend into the sidewall 64, and the protrusion 30 can then enter the sidewall 64 via the cavity 34. In other arrangements, the cavity 34 is positioned below the sidewall 64 in the die segment base height direction 36, and the protrusion 30 is also below the sidewall in this direction 36. The front side 20 engages the sidewall 64 and also does not contact the sidewall 64 along a portion of its length and height. The siping element 14 can be bent in the width direction 24 at its top region to achieve this separation, or the material forming the die segment base 32 and the sidewall 64 can extend away from the siping element 14 at this location, resulting in a space. According to different exemplary embodiments, the siping element 14 can be spaced from the bead 60 by 0.5 mm, 1.0 mm, 1.5 mm, or a distance from 0.01 to 2 mm at its top, thereby forming a siping 82 parallel and adjacent to the groove 90.

[0047] Figure 17 and Figure 18 The flexible die segment 10 arranged as set in is configured to produce a production die 92 capable of forming Figure 19 the tread 84 shown. It should be understood that Figure 19 only a portion of the tread 84 is shown, and includes a circumferential groove 90 formed by Figure 17 and Figure 18 the bead 60. The circumferential siping 82 is positioned adjacent to the circumferential groove 90 and is formed by the siping element 14. The arrangement including the protrusion 30 and the cavity 34 allows the siping element 14 to be stabilized within the die segment base 32, such that the circumferential siping 82 can actually be precisely positioned adjacent to and parallel to the circumferential groove 90. The siping 82 has a width that can be two millimeters or less. The circumferential siping 82 can be parallel to the circumferential groove 90 along the entire circumferential length of the circumferential groove 90, or can be parallel to the circumferential groove only along a portion of the circumferential length of the circumferential groove 90.

[0048] Figure 20Shows a portion of the master mold 52 according to an exemplary embodiment. The master mold 52 also includes the preliminary tread pattern 56 placed in the master mold base 54 as previously discussed. However, the preliminary tread pattern 56 has preliminary tread pattern protrusions 58 extending from its face. The preliminary tread pattern protrusions 58 are used to form the cavity 34 of the mold segment base 32. In this regard, a material constituting the flexible mold segment 10, such as polysulfide castable mold rubber or Silastic, is poured over the preliminary tread pattern 56 and the master mold base 54. When the hardened mold segment base 32 is peeled from the master mold 52, the presence of the preliminary tread pattern protrusions 58 forms the cavity 34 in the mold segment base 32. It should be understood that this method is only one way of manufacturing the cavity 34, and according to other exemplary embodiments, other methods are possible. In other arrangements, the recess 33 need not be present either. The tread pattern element 14 is made of a material harder than the material constituting the mold segment base 32. The master mold 52 can be formed via a variety of different methods, and in some instances, the preliminary tread pattern 56 is a separate piece inserted into the master mold base 54. In other instances, the preliminary tread pattern 56 and the master mold base 54 are formed by stereolithography techniques such that the master mold base 54, the preliminary tread pattern 56 with the preliminary tread pattern protrusions 58 are all formed as a single component without the need to be assembled together.

[0049] Although the invention has been described in connection with certain preferred embodiments, it should be understood that the subject matter covered by the invention is not limited to those particular embodiments. On the contrary, it is intended that the subject matter of the invention include all alternatives, modifications, and equivalents that may be included within the spirit and scope of the appended claims.

Claims

1. A die segment for forming a tire, comprising: a tread element having a first end and a second end, wherein the tread element has a first side and an oppositely disposed second side in a width direction of the tread element, wherein the tread element has a bottom and an oppositely disposed top in a height direction of the tread element, and wherein the tread element has a plurality of protrusions extending from the first side such that the second side does not have any of the protrusions located thereon; and a die segment base made of a material more flexible than the material forming the tread element, wherein the die segment base receives the tread element such that the bottom of the tread element is located inside the die segment base and the top of the tread element is located outside the die segment base, wherein the die segment base defines a plurality of cavities, and wherein the protrusions are located inside the cavities, wherein the die segment base is for producing a plaster casting segment for forming the tire, and wherein the die segment base is not a production die segment base; wherein the die segment base is a flexible die segment base and not a plaster casting, and the plurality of protrusions are located within the flexible die segment base and not within the plaster casting or the production die segment base.

2. The die segment according to claim 1, wherein the die segment base is made of polysulfide castable mold rubber, and wherein the tread element is forced into the polysulfide castable mold rubber to be received therein.

3. The die segment according to claim 1, wherein the die segment base has a die segment base height direction, wherein the die segment base has an upper surface and an oppositely disposed lower surface in the die segment base height direction, and wherein the cavities are located inside the die segment base so as to be spaced apart from both the upper surface and the lower surface in the die segment base height direction; wherein the cavities are located inside the die segment base such that the material forming the die segment base is directly above and directly below the cavities in the die segment base height direction and at least partially defines the cavities.

4. The die segment according to claim 1, wherein the tread element has a length direction extending from the first end to the second end, wherein the protrusions are spaced apart from both the first end and the second end in the length direction such that the protrusions are not located at the first end or the second end, and wherein the protrusions are spaced apart from both the top and the bottom in the height direction such that the protrusions are not located at the top or the bottom.

5. The die segment according to claim 4, wherein the protrusions are longer in the length direction than in the height direction.

6. The die segment according to claim 4, wherein the protrusions are longer in the height direction than in the length direction.

7. The die segment according to claim 1, wherein the cavity has the same shape as the protrusion.

8. The die segment according to claim 1, wherein the cavity is dimensioned relative to the protrusion such that an interference fit is formed when the protrusion is inserted into the cavity, and wherein the die segment base engages the protrusion at opposite ends of the protrusion in the height direction.

9. The die segment according to claim 1, wherein the protrusion has a lip that defines a space in the width direction between the first side and the lip, and wherein the cavity has a lip receiving portion that receives the lip such that the lip engages the material constituting the die segment base on opposite sides of the lip in the width direction.

10. The die segment according to claim 1, further comprising a master die that includes a master die base and a primary tread having primary tread protrusions, wherein the die segment base is cast on and formed from the master die such that the primary tread protrusions form one of the cavities in the die segment base.

11. The die segment according to claim 10, wherein the master die base and the primary tread having the primary tread protrusions are all formed by stereolithography such that the master die base and the primary tread having the primary tread protrusions are all formed as a single component without being assembled together.

12. The die segment according to claim 1, wherein the tread element having the protrusion is formed by additive manufacturing.

13. The die segment according to claim 1, wherein the die segment base has a bead that forms a groove for the tire, and wherein the bead has a sidewall, and wherein the tread element engages the sidewall of the bead.

14. The die segment according to claim 13, wherein the first side engages the sidewall of the bead along the length direction of the tread element, and wherein the cavity is located in the sidewall of the bead.

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