Bimetallic build drum for non-pneumatic tire component

Abstract

A method is provided that incorporates a build drum that has a base that is made of a first metal, and an expansion member that is made of a second metal. The second metal has a higher coefficient of thermal expansion than does the first metal such that the second metal expands at a higher rate than does the first metal. An uncured non-pneumatic tire component is built on a build surface of the expansion member. The build drum and the built non-pneumatic tire component are placed into a mold that has a plurality of mold sectors. Heat is applied to the build drum to cause the expansion member to expand and apply force to the non-pneumatic tire component outward in the radial direction. The plurality of mold sectors engage the nonpneumatic tire component, and the non-pneumatic tire component is cured in the mold.

Description

DescriptionTitle of Invention: BIMETALLIC BUILD DRUM FOR NON-PNEUMATIC TIRE COMPONENTFIELD OF THE INVENTION

[0001] The present invention relates generally to a bimetallic build drum for use in the construction of non-pneumatic tire components such as a shear bands and treads. More particularly, the present application involves a method of using a bimetallic build drum to build, cure, and extract a non-pneumatic tire component that features two metals having different coefficients of thermal expansion.BACKGROUND OF THE INVENTION

[0002] Airless tires, often called non-pneumatic tires, are tires that lack an inflation cavity and instead rely on spokes, a web or other solid structure for support. A typical design of a non-pneumatic tire may include a central hub from which a series of spokes extend radially outward. The ends of these spokes engage the inner surface of a shear beam component of the non-pneumatic tire, and a tread that is designed for engaging the ground is located on this shear beam. To manufacture components of a non- pneumatic tire, it is known to form them at least partially of rubber and then cure them using a press. A preferred press for molding a non-pneumatic tire component does not incorporate an inflation bladder in the interior of the mold that applies pressure radially outward to the non-pneumatic tire component during the curing process. Instead, a press of this type includes a solid core that is surrounded by the non-pneumatic tire component, and mold sectors push inward in the radial direction to apply force to the non-pneumatic tire component during the curing process. This method of formation misses out on pressure development during the early stages of the curing process because there is no outward radial force being applied to the non-pneumatic tire component. Uniformity issues may result from the lack of an outward radial force being applied to the non-pneumatic tire component during the curing phase.

[0003] The uncured non-pneumatic tire component is first built upon a segmented build drum, after which time it is removed and placed into the mold for curing. The segmented build drum is a cylindrical component that is made of three to twenty segments positioned 360 degrees about a central axis. The use of a segmented build surface causes the resulting non-pneumatic tire component to likewise have steps formed in its construction due to the unevenness of the various build segments. These steps in the non-pneumatic tire component can likewise lead to uniformity issues in the final product. Various methods of curing the non-pneumatic tire component involve removing it from the build drum and then transporting just the uncured non-pneumatic tire component to the curing press. These methods require the extra step of removal from the build drum and then reapplication of the uncured non-pneumatic tire component to a solid core of the curing press. These various steps increase the time it takes to build the non-pneumatic tire component and increases the complexity of the process. Although ways of building non-pneumatic tire components are known, there remains room for variation and improvement within the art.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, which makes reference to the appended Figs, in which: [Fig 1]

[0005] [Fig.1] is a side view of a build drum that is being rotated and having a non- pneumatic tire component built thereon.[Fig 2]

[0006] [Fig.2] is a cross-sectional view taken along line 2-2 of [Fig.l].[Fig 3]

[0007] [Fig.3] is a side view of a build drum with a non-pneumatic tire component built thereon after building but before curing.[Fig 4]

[0008] [Fig.4] is an exploded perspective view of a mold.[Fig 5]

[0009] [Fig.5] is a top view of a portion of the mold with the build drum and non-pneumatic tire component disposed therein.[Fig 6]

[0010] [Fig.6] is a cross-sectional view of a mold with the build drum and non-pneumatic tire component located therein without heat applied and with the expansion member unexpanded.[Fig 7]

[0011] [Fig.7] is a cross-sectional view of a mold with the build drum and non-pneumatic tire component located therein with heat applied and with the expansion member expanded.[Fig 8]

[0012] [Fig.8] is a cross-sectional view of a portion of a build drum and non-pneumatic tire component arranged in an alternate configuration with the expansion member unexpanded.[Fig 9]

[0013] [Fig-9] is a cross-sectional view of a portion of a build drum and non-pneumatic tire component arranged in an alternate configuration with the expansion member expanded.[Fig 10]

[0014] [Fig.10] is a side view of a non-pneumatic tire that includes the formed nonpneumatic tire component.

[0015] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a third embodiment. It is intended that the present invention include these and other modifications and variations.

[0017] A method for forming a non-pneumatic tire component 18 is provided that utilizes a build drum 10 and a mold 28. The build drum 10 has a base 12 that is made of a first metal, and an expansion member 14 that is made of a second metal. The second metal has a higher coefficient of thermal expansion than does the first metal so that the second metal expands at a higher rate than does the first metal. An uncured non- pneumatic tire component 18 is build upon a build surface 16 of the expansion member 14, and this building may include rotating the build drum 10. Once built, the uncured non-pneumatic tire component 18 is retained on the build drum 10 and this assembly is moved into a mold 28 that has a plurality of mold sectors 30. Heat is applied to the build drum 10 to cause the expansion member 14 to expand outward in the radial direction 26 and in turn apply force to the interior of the non-pneumatic tire component 18 outwards in the radial direction 26. The base 12 provides strength to the build drum 10 and prevents it from deforming due to the curing forces applied to the build drum 10 during curing. Once cured, the build drum 10 with the now cured non-pneumatic tire component 18 can be removed from the mold 28 and moved to a cooling station as a complete assembly. Cooling and consequential shrinkage of the expansion member 14 may allow for the cured non-pneumatic tire component 18 to be more easily removed from the build drum 10.

[0018] With reference to [Fig.l], a non-pneumatic tire component 18 is wound onto a build drum 10. The non-pneumatic tire component 18 is uncured and can be a component of a non-pneumatic tire 44 such as a shear beam 32. The shear beam 32 could be a single layer of material, or can be multiple layers of material that are built upon one another.For example, the shear beam 32 could include multiple layers of rubber disposed between layers of chords. There may be 8 layers of chords in some embodiments. The build drum 10 is rotated in the counterclockwise direction 46 in the circumferential direction 24 about its central axis 20, and the uncured non-pneumatic tire component 18 is wound onto the build drum 10. Although not shown in [Fig.l], the non-pneumatic tire component 18 could also include tread rubber 34 that is applied on top of the shear beam 32 at this stage of the process such that the tread rubber 34 is built on top of the shear beam 32 as a single layer or as multiple layers. The non-pneumatic tire component 18 can be made of any number of layers laid on top of one another, or may be a single layer, and may be made of a variety of materials including uncured rubber.

[0019] With reference to both Figs. 1 and 2, a holding device 50 is inserted into the build drum 10 and has five grasping arms 48 that are extended outward in the radial direction 26 until they come into engagement with the inside of the build drum 10. Upon engagement, the build drum 10 can be securely held by the grasping arms 48, and the holding device 50 can rotate in the counterclockwise direction 46 to in turn cause the held build drum 10 to likewise rotate in the counterclockwise direction 46. This rotation of the build drum 10 in the circumferential direction 24 causes the non-pneumatic tire component 18 to be wound onto the build drum 10. As shown in [Fig.2], a shaft of the holding device 50 is coaxial with the central axis 20 of the build drum 10 and the grasping arms 48 are positioned in the axial direction 22 so as to be at the axial midpoint of the build drum 10. These grasping arms 48 could alternatively be at different positions in the axial direction 22 so as to grasp the build drum 10 at a different axial position from that illustrated. The build drum 10 is ring shape and extends 360 degrees about its central axis 20. Although 5 grasping arms 48 are shown, it is to be understood that any number of grasping arms 48 can be present in other exemplary embodiments. For example, 6 grasping arms 48 could be present, and in fact from 3 to 24 grasping arms could be present in yet other embodiments.

[0020] The build drum 10 has a base 12 that extends 360 degrees about the central axis 20 and is made of a first metal that can be steel in some instances. The first metal should be strong enough to prevent deformation of the build drum 10 when the build drum 10 is subjected to curing forces when in a mold 28. The base 12 extends the entire length of the build drum 10 in the axial direction 22 and has a first flange 36 and a second flange 38. The two flanges 36, 38 are separated from one another in the axial direction 22, and are both spaced inward in the axial direction 22 so that neither of them are located at the terminal ends of the base 12 in the axial direction 22. Both flanges 36, 38 extend completely 360 degrees about the central axis 20 in the circumferential direction 24. The first flange 36 extends outward in the radial direction 26 and terminates at a first outer surface 40 that is the farthest outward extent of thefirst flange 36 in the radial direction 26 from the central axis 20. The second flange 38 terminates at a second outer surface 42 that is the farthest portion of the second flange 38 from the central axis 20 in the radial direction 26. The outer surfaces 40, 42 extend completely 360 degrees about the central axis 20 in the circumferential direction 24. The first outer surface 40 and the second outer surface 42 are both located the same distance from the central axis 20 in the radial direction 26 and are the portions of the base 12 that are farthest from the central axis 20 in the radial direction 26.

[0021] The build drum 10 includes an expansion member 14 that is made of a second metal, and this second metal is different from the first metal in that the second metal has a higher coefficient of thermal expansion than does the first metal so that the second metal expands at a higher rate than does the first metal. The second metal can be aluminum in some embodiments. The expansion member 14 is located in the axial direction 22 so that it is not at either of the axial terminal end of the build drum 10. The expansion member 14 extends completely 360 degrees about the central axis 20 in the circumferential direction 24. The expansion member 14 is not in an expanded configuration as shown in Figs. 1 and 2, and in the non-expanded state the expansion member 14 engages the first and second flanges 36 and 38. In the non-expanded state, the expansion member 14 is sized in the radial direction 26 so as to extend up to the position of the first and second outer surfaces 40, 42. In this regard, the outer surface of the expansion member 14 is a build surface 16 that has a position in the radial direction 26 that is the same as the radial position of the first and second outer surfaces 40, 42. The expansion member 14 in the non-expanded configuration completely fills the pocket formed by the flanges 36, 38. The build surface 16 is continuous 360 degrees in the circumferential direction 24 about the central axis 20, and there is no space or discontinuity at any portion of the build surface 16 about its circumferential length. The build surface 16 may be non-segmented so that the expansion member 14 and the build surface 16 are made of a single piece of material and are not multiple sections placed against one another 360 degrees about the central axis 20. In this regard, the expansion member 14 and the build surface 16 may be described as being non-segmented.

[0022] The build surface 16 is aligned with the first and second outer surfaces 40, 42 so that all of these surfaces 16, 40, 42 are positioned the same distance from the central axis 20 in the radial direction 26 when the expansion member 14 is in the non-expanded configuration. However, this need not be the case in other configurations of the build drum 10. The non-pneumatic tire component 18 is wound onto the build surface 16 and engages the build surface 16 in the embodiment of Figs. 1 and 2. The non-pneumatic tire component 18 does not engage the flanges 36, 38 or any other portion of the base 12. In this regard, the only component that the non-pneumatic tire component 18engages is the expansion member 14 of the build drum 10 and no other portion of it or of any other element. The non-pneumatic tire component 18 in this embodiment is a shear beam 32 and any desired number of layers of the shear beam 32 can be wound onto the build surface 16.

[0023] Once the non-pneumatic tire component 18 is built to a desired height / thickness, it can be cut and stuck onto itself. This may be accomplished by the tackiness of the material making up the uncured non-pneumatic tire component 18, or can be made through adhesion or via a piece of sticky rubber applied to the cut portion of the non- pneumatic tire component 18. Once the uncured non-pneumatic tire component 18 is built, it is moved as an assembly with the build drum 10 to a mold 28. [Fig.3] shows the build drum 10 with the built non-pneumatic tire component 18 thereon as it would look after the building stage. In this embodiment, the non-pneumatic tire component 18 was built upon the build drum 10 as a shear beam 32 with tread rubber 34 engaging and radially outward from the shear beam 32. The tread rubber 34 can be a single layer of rubber laid onto the shear beam 32 during building, or the tread rubber 34 can be multiple layers of rubber that are wound onto one another and the shear beam 32 during formation. The tread rubber 34 is a type of rubber that can function as the tread of the non-pneumatic tire 44 when constructed and is a type of rubber that is selected to engage the road surface. In the building stage, the tread rubber 34 does not have any architectural features such as grooves, tread blocks, ribs, sipes, or stone ejectors formed therein, but has a smooth outer surface. The tread rubber 34 is built directly on top of the shear beam 32 and does not engage any portion of the build drum 10, but only engages the shear beam 32.

[0024] [Fig.4] shows a mold 28 for curing a non-pneumatic tire 44, or a portion of a non- pneumatic tire 44. The build drum 10 with the built non-pneumatic tire component 18 may be placed into the mold 28 for curing at which time heat and pressure are applied to cure the uncured non-pneumatic tire component 18. The mold 28 can be configured in a variety of ways. In the embodiment illustrated, the mold 28 includes a garniture that has a series of mold sectors 30 that engage the non-pneumatic tire component 18 to form the tread of the non-pneumatic tire 44. The mold 28 includes a mold top 52 and a mold bottom 54 that may engage portions of the non-pneumatic tire component 18 to impart architecture and mold these components. For example, the mold top 52 and mold bottom 54 may engage part of the tread rubber 34 and / or the shear beam 32 to form these portions of the non-pneumatic tire 44. In other arrangements, the mold top 52 and mold bottom 54 do not engage the tread rubber 34 or the shear beam 32 and do not function to impart architecture to these component during cure of the non-pneumatic tire component 18. In the disclosed embodiment, there are eight mold sectors 30, although two of these mold sectors 30 are not shown in [Fig.4] for purposesof clarity. In other embodiments, any number of mold sectors 30 can be present in the mold 28. In some embodiments, there are 31 mold sectors 30. Other embodiments are possible in which there are from 3 to 75 mold sectors 30. The mold sectors 30 on their interior surfaces have a tread pattern 56 that is sized and shaped to provide a desired tread pattern into the tread rubber 34 during curing of the non-pneumatic tire component 18. This tread pattern 56 can be variously shaped and can be used to impart grooves, ribs, sacrificial ribs, blocks, sips, stone ejectors, wear bars, and another desired architecture into the tread rubber 34 of the non-pneumatic tire 44. In other embodiments of the method, a single mold sector is employed instead of multiple mold sectors 30.

[0025] In the next step in the method, the build drum 10 with the built non-pneumatic tire component 18 is placed inside of the mold sectors 30, and the mold top 52 and mold bottom 54 can be positioned against the non-pneumatic tire component 18. The non- pneumatic tire component 18 thus does not have to be removed from the build drum 10 before curing after building, but can instead remain on the build drum 10 during the curing phase of the process. If the mold top 52 and mold bottom 54 are not designed to engage the non-pneumatic tire component 18, they can be placed adjacent the build drum 10 and / or the mold sectors 30. [Fig.5] shows the mold 28 with the mold top 52 not shown for clarity. The interior of the mold 28 includes eight heating elements 58 that are disposed radially inward from the build drum 10, and the build drum 10 surrounds these heating elements 58. The mold 28 does not include an inflatable bladder. Instead, the heating elements 58 also function as a base for the build drum 10 as the interior of the build drum 10 engages the outer surfaces of the heating elements 58. The heating elements 58 will not apply an outward radial force that is transferred to the non-pneumatic tire component 18, but will instead resist compressive forces that are applied to the non-pneumatic tire component 18 radially inward. As such, with the solid build drum 10, the mold 28 does not apply curing forces outward onto the interior surfaces of the non-pneumatic tire component 18, but instead applies them, if at all, inward in the radial direction 26 from the exterior of the non-pneumatic tire component 18. Any radially outward force application to the non-pneumatic tire component 10 is applied via expansion of the expansion member 14. The heating elements 58 apply heat to the build drum 10 which in turn is transferred into the carried non-pneumatic tire component 18. The mold 28 receives the same exact build drum 10 that was used to build the non-pneumatic tire component 18 thereon so that both elements 10, 18 are inserted into the mold 28 after the building step with no removal of the non-pneumatic tire component 18 from the build drum 10.

[0026] The mold sectors 30 are positioned radially outward from the non-pneumatic tire component 18 such that the non-pneumatic tire component 18 and the build drum10 are located radially between the heating elements 58 and the mold sectors 30. In some arrangements the mold sectors 30 move radially inward to apply pressure to the non-pneumatic tire component 18 to cause curing. Additionally, the mold sectors 30 can include their own heating elements that generate heat that is transferred into the non-pneumatic tire component 18 during curing. As such, the process employs a radially expanding expansion member 14, and mold sectors 30 that may or may not apply a radially compressive force to the non-pneumatic tire component 18. In some arrangements the mold sectors 30 do not apply heat to the non-pneumatic tire component 18. [Fig.6] shows the mold 28 with the build drum 10 inserted therein before heating of the non-pneumatic tire component 18. As shown, an inflatable bladder is not used. Instead, the base 12 engages the radially outward surfaces of the heating elements 58. The heating elements 58 do not move radially inward or outward during cure. The expansion member 14 is in an unexpanded configuration in [Fig.6]. The tread rubber 34 and the shear beam 32 rest within a pocket defined by the mold sectors 30 and the expansion member 14, and the tread rubber 34 is adjacent the tread pattern 56 of the mold sectors 30 but is not within the tread pattern 56. The mold top 52 and the mold bottom 54 are closed in position, but they do not engage the non- pneumatic tire component 18. The mold 28 includes a brace 60 through which the central axis 20 extends, and this brace 60 is used to resist crushing forces from the curing that would be directed radially inward. This brace 60 could extend the entire height of the mold 28 in other embodiments so that it engages both the mold top 52 and the mold bottom 54, or alternatively this brace 60 need not be present in other arrangements of the mold 28.

[0027] The application of heat by the heating elements 58 causes the build drum 10 and the non-pneumatic tire component 18 to become hotter. This heat results in the expansion member 14 enlarging at a faster rate than the base 12 due to the second metal of the expansion member 14 having a higher coefficient of thermal expansion than the first metal that makes up the base 12. The mold 28 and associated components are shown as being heated with reference to [Fig.7] . Here, the expansion member 14 expands from the state shown in [Fig.6] so that it expands outward in the radial direction 26. The first metal of the base 12 does not expand at a rate as fast as that of the expansion member 14 and the expansion member 14 expands at a rate faster than it and radially outward relative to the base 12. The flanges 36, 38 prevent the expansion member 14 from expanding in the axial direction 22 so that its expansion is confined to only the radial direction 26. The mold sectors 30 do not expand at a rate as fast as the expansion member 14. In the expanded configuration, the expansion member 14 pushes the non-pneumatic tire component 18 outwards in the radial direction 26 so that the tread rubber 34 is pushed into the tread pattern 56. This force on the non-pneumatic tirecomponent 18 in combination with the heat applied by the heating elements 58 cures the non-pneumatic tire component 18 so long as they are applied for a sufficient amount of time. In some embodiments, the mold sectors 30 can also apply a force to the non-pneumatic tire component 18 as they are forced inwards in the radial direction 26 and act against the radial outward force of the expansion member 14 to squeeze the non-pneumatic tire component 18 therebetween. As such, the force applied during molding may come solely from expansion of the expansion member 14, or may come from both expansion of the expansion member 14 and some other mold 28 component such as the mold sectors 30. The tread rubber 34 is pushed into the tread pattern 56 so that architectural elements such as grooves, blocks, sipes, stone ejectors, ribs, wear bars, sacrificial ribs and others can be imparted into the tread rubber 34 and formed into the non-pneumatic tire 44.

[0028] The second metal has a higher coefficient of thermal expansion than does the first metal and will expand at a greater rate for the same temperature increase. The coefficients of thermal expansion of the first metal and of the second metal can be measured using ASTM E831-14 Standard Test Method for Linear Thermal Expansion of Solid Materials by Thermomechanical Analysis that is in effect as of June 1, 2024. When the first metal is steel, its coefficient of thermal expansion may be 11 X 10A-6 / °C. The second metal can be aluminum and its coefficient of thermal expansion can be 23 X 10A-6 / °C.

[0029] The temperature in the mold 28 during curing may be from 130 degrees Centigrade to 170 degrees Centigrade. The pressures developed during curing may be from 30 bar to 140 bar. The base 12 should be made of a material that is strong enough to withstand these crushing forces and these temperatures. The first metal making up the base 12 can be steel in accordance with some exemplary embodiments. The first metal can have a higher yield strength than the second metal. The yield strength is the point at which the material permanently deforms under a stress. Steel can withstand greater force before it begins bending out of shape. The yield strength of the first and second metals may be measured using ASTM E8 / E8M-22 Standard Test Methods for Tension Testing of Metallic Materials that is in effect as of June 1, 2024. The first metal may also have a higher modulus of elasticity than the second metal. The modulus of elasticity of a metal is a property of its stress to strain. A higher modulus of elasticity means that the material deforms less for a given amount of stress. The first metal can have a higher modulus of elasticity than the second metal. The modulus of elasticity of the first metal and the second metal are measured using ASTM E2769-22 Standard Test Method for Elastic Modulus by Thermomechanical Analysis Using Three-Point Bending and Controlled Rate of Loading that is in effect as of June 1,2024. Making the base 12 out of steel will cause the base 12 to deform less for a given amount of pressure applied in the mold 28.

[0030] The second metal can be selected so that it has a higher thermal conductivity than that of the first metal. This property will increase the speed of heat transfer since the second metal will be in contact with the non-pneumatic tire component 18. This will result in good rubber quality since the rubber will not be overcured in the press 28. The thermal conductivity of the first metal and the second metal can be measured using ASTM El 225-20 Standard Test Method for Thermal Conductivity of Solids Using the Guarded-Comparative-Longitudinal Heat Flow Technique that is in effect as of June 1, 2024. The first metal when provided as steel can have a thermal conductivity of 50 Watts / meter X degree Kelvin. The second metal when provided as aluminum can have a thermal conductivity of 237 Watts / meter X degree Kelvin.

[0031] After the non-pneumatic tire component 18 has been cured in the mold 28, the mold 28 is opened and the build drum 10 with the cured non-pneumatic tire component 18 are removed as a unit from the mold 28. The build drum 10 and the carried non- pneumatic tire component 18 are moved to a cooling station which may cool these components, or which may simply allow them to cool at room temperature away from the heat of the mold 28. Although described as being cured, it is to be understood that the heat in the build drum 10 itself may still function to cure the non-pneumatic tire component 18 when removed from the mold 28, so that the non-pneumatic tire component 18 undergoes some degree of curing even when removed from the mold 28 and placed into the cooling station. The cooling station need not be any particular object, but could just be a place for the build drum 10 / non-pneumatic tire component 18 to cool. Upon cooling, the expansion member 14 will shrink from the position shown in [Fig.7] to the position as originally illustrated in [Fig.6] in the non-expanded configuration. This shrinkage will reduce holding force on the non-pneumatic tire component 18 so that it will be easier for the non-pneumatic tire component 18 to be removed from the build drum 10. The same build drum 10 and non-pneumatic tire component 18 are thus present at the building of the non-pneumatic tire component 18, curing, and then finally cool down after which time the non-pneumatic tire component 18 is removed from the build drum 10. The higher coefficient of thermal expansion of the second metal allows the expansion member 14 to shrink faster than the base 12 during the cooling and allows the non-pneumatic tire component 18 to be removed from the build drum 10. Shrinkage of the expansion member 14 creates a gap as compared to the size of the cured non-pneumatic tire component 18 to allow it to be separated.

[0032] After removal from the build drum 10, the cured shear beam 32 and tread rubber 34 can have spokes 62 attached to the inner surface of the shear beam 32, and a hub64 may be attached to the ends of the spokes 62 at the radial center to form a nonpneumatic tire 44 as shown for example in [Fig.10]. Any number of spokes 62 can be employed and they can be variously configured. The spokes 62 may be attached to the shear beam via adhesion. Alternatively, the spokes 62 may have installed at their outer radial ends a ring that is in turn subsequently attached to the inner surface of the shear beam 32. The non-pneumatic tire component 18 that is constructed can be just the shear beam 32, just the tread rubber 34, both the shear beam 32 and tread rubber 34, or any other portion of a non-pneumatic tire 44 as desired.

[0033] The build drum 10 may be designed in a variety of manners. With reference to [Fig.8], a portion of the build drum 10 is shown in cross-section in accordance with another embodiment. The expansion member 14 is in a non-expanded configuration and has a build surface 16 that is not at the same radial position as the outer surfaces 40, 42. Instead, the build surface 16 is located radially inward from the outer surface 40, 42. The non-pneumatic tire component 18 is disposed on the build surface 16 and engages both of the flanges 36, 38. The non-pneumatic tire component 18 extends in the radial direction so that its outermost surface is at the same radial position as the outer surfaces 40, 42 upon completion of building of the non-pneumatic tire component 18. When heat is applied to the build drum 10, the expansion member 14 expands into the position shown with reference to [Fig.9]. Here, the expansion member 14 expands only in the radial direction 26 and not in the axial direction 22 due to the presence of the flanges 36, 38 which constrain and prevent expansion in the axial direction 22. The non-pneumatic tire component 18 is pushed outwards in the radial direction 26 and above / radially outward of the outer surfaces 40, 42. The maximum expansion of the expansion member 14 causes the build surface 16 to still not extend in the radial direction 26 to the outer surfaces 40, 42 but instead still be positioned inward of the outer surfaces 40, 42 in the radial direction 26. Although shown as employing a pair of flanges 36, 38, it is to be understood that they are only present in some embodiments, and one or both of the flanges 36, 38 can be absent in other embodiments of the method. Also, although shown as expanding only in the radial direction 26, the expansion member 14 may in addition expand in both the axial direction 22 and radial direction 26 in other embodiments. This expansion in the axial direction 22 may be constrained to expansion in just one axial direction 22, or the expansion member 14 may be free to expand in both axial directions 22 such that it can expand both left and right with reference to [Fig.9].

[0034] The build drum 10 functions so that the increased expandability during heating of the expansion member 14 causes force to be applied radially outward to the non-pneumatic tire component 18 during curing. The strength provided by the metal making up the base 12 prevents the build drum 10 from being crushed or otherwise deformed duringcuring when in the press 28. Although the first metal has been described as being steel, and the second metal has been described as being aluminum, it is to be understood that the selection of these materials is only exemplary and that the first and / or second metal can be different than steel and aluminum in other embodiments. In some instances, both the first metal and the second metal are made of steel, but of different types of steel so that the steel making up the second metal has a higher coefficient of thermal expansion than does the steel making up the first metal.

[0035] Once the non-pneumatic tire component 18 has cooled sufficiently at the cooling station and has been removed from the build drum 10, it can be incorporated with other components into the formation of a non-pneumatic tire 44. [Fig.10] shows one example of how the non-pneumatic tire 44 can be configured. Spokes 62 are attached to the radially inner surface of the non-pneumatic tire component 18 and extend completely around the central axis of the non-pneumatic tire 44. The spokes 62 are attached to the inner surface of the shear beam 32 in this regard. The opposite ends of the spokes 62 are attached to a hub 64 that is the radially inward most component of the non- pneumatic tire 44. This hub 64 can be mounted onto a wheel of a vehicle, and the tread rubber 34 with the molded in architectural features can engage the ground onto which the non-pneumatic tire 44 rolls. Although shown as employing spokes 62, it is to be understood that this portion of the non-pneumatic tire 44 can be variously configured and need not include spokes 62 in other embodiments and may instead be a web structure, a plate structure, a honeycomb support structure, or otherwise configured.

[0036] While the present invention has been described in connection with certain preferred embodiments, it is to be understood that the subject matter encompassed by way of the present invention is not to be limited to those specific embodiments. On the contrary, it is intended for the subject matter of the invention to include all alternatives, modifications and equivalents as can be included within the spirit and scope of the following claims.

Claims

Claims

1. A method, comprising: providing a build drum that has a central axis that extends in an axial direction, wherein the build drum has a circumferential direction and a radial direction, wherein the build drum has a base that is made of a first metal, wherein the build drum has an expansion member that is made of a second metal, wherein the expansion member is located in the radial direction outward from at least a portion of the base, wherein the expansion member has a build surface, and wherein the second metal has a higher coefficient of thermal expansion than does the first metal such that the second metal expands at a higher rate than does the first metal; building a non-pneumatic tire component on the build surface, wherein the expansion member is located between the nonpneumatic tire component and at least a portion of the base, and wherein the non-pneumatic tire component is located outward in the radial direction from the expansion member, wherein the non-pneumatic tire component is uncured when built on the build surface; placing the build drum with the built non-pneumatic tire component into a mold that has a plurality of mold sectors; applying heat to the build drum to cause the expansion member to expand and apply force to the non-pneumatic tire component outward in the radial direction, wherein the plurality of mold sectors engage the non-pneumatic tire component, and wherein the non-pneumatic tire component is cured in the mold.

2. The method of claim 1, wherein the non-pneumatic tire component is cured in the mold without use of a bladder.

3. The method of claim 1 or 2, wherein the non-pneumatic tire component is a shear beam.

4. The method as set forth in any one of claims 1 to 3, wherein the non-pneumatic tire component has tread rubber, and wherein the plurality of mold sectors impart a tread pattern onto the tread rubber when the non-pneumatic tire component is cured in the mold.

5. The method as set forth in any one of claim 1 to 4, wherein the coefficient of thermal expansion of the first metal and of thesecond metal are measured using ASTM E831-14 Standard Test Method for Linear Thermal Expansion of Solid Materials by Thermomechanical Analysis that is in effect as of June 1, 2024.

6. The method as set forth in any one of claims 1 to 5, wherein the second metal has a higher thermal conductivity than the first metal, and wherein the thermal conductivities of the first metal and of the second metal are measured using ASTM E1225-20 Standard Test Method for Thermal Conductivity of Solids Using the Guarded-Comparative-Longitudinal Heat Flow Technique that is in effect as of June 1, 2024.

7. The method as set forth in any one of claims 1 to 6, wherein the first metal has a higher modulus of elasticity than the second metal, and wherein the modulus of elasticity of the first metal and the second metal are measured using ASTM E2769-22 Standard Test Method for Elastic Modulus by Thermomechanical Analysis Using Three-Point Bending and Controlled Rate of Loading that is in effect as of June 1, 2024; wherein the first metal has a higher yield strength than the second metal, and wherein the yield strength of the first metal and the second metal are measured using ASTM E8 / E8M-22 Standard Test Methods for Tension Testing of Metallic Materials that is in effect as of June 1, 2024.

8. The method as set forth in any one of claims 1 to 7, further comprising: removing the build drum with the non-pneumatic tire component disposed thereon from the mold after cure; and cooling the non-pneumatic tire component as the non-pneumatic tire component is disposed on the build drum after removal from the mold.

9. The method as set forth in any one of claim 1 to 8, wherein the build surface is non- segmented and is a continuous surface that extends continuously 360 degrees in the circumferential direction about the central axis.

10. The method as set forth in any one of claim 1 to 9, wherein the building of the non-pneumatic tire component on the build surface comprising rotating the build drum about the central axis to wind the non-pneumatic tire component onto the build surface.

11. The method as set forth in any one of claims 1 to 10, wherein the base has a first flange and a second flange that extend therefrom in the radial direction, wherein the expansion member is located between the first flange and the second flange in the axial direction, and wherein the expansion member engages the first flange and the second flange during the building of the nonpneumatic tire component on the build surface.

12. The method as set forth in claim 11, wherein the first flange has a first outer surface and wherein the second flange has a second outer surface, wherein the first outer surface, the second outer surface, and the build surface are all located at the same distance from the central axis in the radial direction during building of the non-pneumatic tire component on the build surface.

13. The method as set forth in claim 1, wherein the mold sectors do not apply any force to the non-pneumatic tire component when the non-pneumatic tire component is cured in the mold, and wherein all of the force applied to the non-pneumatic tire component when the non-pneumatic tire component is cured in the mold is from the expansion member.

14. The method as set forth in any one of the preceding claims, wherein the first metal is steel, and wherein the second metal is aluminum.

15. The method as set forth in any one of the preceding claims, wherein expansion of the expandable member is only in the radial direction and is not in the axial direction.

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