WO2023018964A1

WO2023018964A1 - Multi-gate molten feedbox system

Info

Publication number: WO2023018964A1
Application number: PCT/US2022/040212
Authority: WO
Inventors: Henry L. RENEGAR; Suresh B. GOVINDASWAMY; Miguel SANZHEZ-ARAIZA
Original assignee: Superior Industries International Inc.
Priority date: 2021-08-12
Filing date: 2022-08-12
Publication date: 2023-02-16
Also published as: WO2023018964A8

Abstract

A system for manufacturing a cast alloy wheel includes a mold defining a die cavity being configured to form the alloy wheel that includes a face portion and a. rim portion. A furnace heats the alloy to maintain the alloy in a molten state. A feeder box interconnects the furnace to the mold providing molten alloy to the die cavity. The feeder box defines a gate system with a central axial runner for providing molten alloy to the face portion of the die cavity. A plurality of rim runners provides the molten alloy to the rim portion of the die cavity.

Description

MULTI-GATE MOLTEN FEEDBOX SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63/232,359, filed August 12, 2021, the contents of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

[0002] The present disclosure relates generally toward a feed system for manufacturing an alloy vehicle wheel. More specifically, the present disclosure relates to an improved delivery of molten alloy material to a wheel cavity of a die.

BACKGROUND

[0003] C ast alloy wheels have been in use for automotive vehicles for many years. These types of wheels provide the ability to reduce mass of an automotive vehicle due to the lower weight alloy when compared to older conventional steel wheels that are covered with hubcaps. However, casting molten alloy into a vehicle wheel is a complex, energy consuming process that has made cast alloy wheels more expensive than steel alternatives. Furthermore, with the advent of electric vehicles and ever-increasing improved fuel efficiency standards, it is becoming increasingly important to manufacture a more economical alloy wheel that also provides reduced mass.

[0004] Reducing the cost to manufacture an alloy wheel has proven elusive. Furthermore, reducing mass of a cast alloy wheel has required extreme mechanical design features, or the use of exotic alloys that further drive cost of the cast alloy wheel. Therefore, it would be desirable to develop a manufacturing system that is capable of both reducing manufacturing cost while simultaneously providing the abil ity' to reduce mass of the cast alloy wheel without use of exotic alloys. SUMMARY

[0005] A system for manufacturing a cast alloy wheel includes a mold defining a die cavity being configured to form the alloy wheel that includes a face portion and a rim portion. A furnace heats the alloy to a molten state. A feeder box, or heater box, interconnects the furnace to the mold providing molten alloy to the die cavity. The feeder box defines a system to direct the molten alloy material received from the furnace to the die cavity at multiple gate locations. A plurality of runners provides the molten alloy to the rim portion of the die cavity.

[0006] The system of the present disclosure provides the ability to convert existing furnace technology from a single central runner and a single gate configuration to a multi-gates configuration, via multiple runners branched from a single inlet, without substantial investment. The adoption of the feeder box between the wheel mold and the furnace enables redirection of the molten alloy into multiple portions of the wheel die cavity that increase efficiency and improve mechanical characteristics of the wheel. In addition, the heater box is configured to include heating elements to maintain consistent temperature of the molten alloy while casting the alloy wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Other advantages of the present disclosure will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0008] Figure 1 shows an illustrative perspective view of a cast wheel formed from a die casting system of the present disclosure;

[0009] Figure 2 shows a schematic cross-sectional view' of a die casting system of the present disclosure, including a low-pressure furnace, a feeder box, and a die assembly;

[0010] Figure 3 shows a top perspective view of a feeder box of the present disclosure;

[0011 ] Figure 4 shows a side sectional view of the feeder box, taken along line 4-4 of

Figure 3;

[0012] Figure 5 shows a bottom view of the feeder box of Figure 3; and

[0013] Figure 6 shows a side sectional view of the feeder box through a runner system, taken along line 6-6 of Figure 3. DETAILED DESCRIPTION

[00141 Referring to Figure I, an exemplary’ wheel is shown at 10. The wheel 10 is formed from a die casting system shown at 110 in Figure 2. As will be explained in more detail below, the wheel 10 is formed by injecting molten alloy material into a cavity 156 of a die assembly 152 of the die casting system 110 at a low pressure. The alloy includes, but is not limited to aluminum alloys, Magnesium alloys and the like that are suitable for manufacturing vehicle wheels.

[0015] Referring again to Figure 1 , the wheel 10 may be a cast wheel of the type used for a vehicle. The wheel 10 includes a rim element 12 and a hub 14 radially surrounding an axis A. The hub 14 is generally cylindrical and configured to be operatively attached to the vehicle, e.g., attached to a rotor of the vehicle. The rim element 12 is configured to support a vehicle tire (not shown) relative to the hub. The rim element 12 and the hub 14 are radially spaced from one another. A plurality’ of spokes 22 interconnect the rim element 12 to the hub 14.

[0016| A plurality of connecting elements 22 (e.g., spokes), radially extend between the rim element 12 and the hub 14. The rim element 12 defines a drop surface 16 (or annular wall) that extends between a distal bead 18 and a proximal bead 20 at a location that is disposed radially inwardly from the two beads 18, 20. It should be understood by those of ordinary skill in the art that the proximal bead 18 is located outboard of a motor vehicle (not shown) and the distal bead 20 is located inboard of the vehicle. Furthermore, the drop surface 16 is defined as a cylindrical surface circumscribing the axis A in a known manner.

[0017] The spokes 22 may be configured to define a plurality of openings 26 therebetween.

As explained in more detail below, the die casting system 110 of the present disclosure is configured to form die cast wheels 10 having enhanced stiffness, with reduced mass (unsprung) and a lower inertia, i.e., wheels with most of the weight distributed close to a center (axis A) of the wheel 10. Tn this manner, since there are typically four wheels on a vehicle, the ability to reduce the mass (unsprung) of a wheel 10, while enhancing stiffness and reducing the inertia of is realized at each wheel 10 on the vehicle. It is believed that the improved die casting system 110 achieves all of these performance benefits without the use of exotic alloys while also improving manufacturing efficiency. The die casting system 1 10 provides a more efficient flow of molten alloy into the cavity 156 even though a serpentine flow path is required to meet structural and mass requirements.

[0018] Referring again to Figure 2, the die casting system 1 10 includes a low-pressure furnace 112, a feeder box 132 (i.e., a heater box), and a die assembly 152. The furnace 112 defines a furnace chamber 114 from which a riser 116 extends upwardly. The furnace 1 12 functions in a known manner so that the chamber 1 14 is configured to retain and the alloy at a molten state. The riser 1 16 extends upwardly from the furnace chamber 114 and is fluidly connected to a coupling bushing 120. The coupling bushing 120 is sealed to the riser 1 16 at a first bushing end 122 with a first gasket 124. In one embodiment, the first gasket 124 is formed from ceramic fibers. However, any gasket material sufficient to withstand the rigors of an alloy casting process will suffice. A second bushing end 126 interconnects with a feeder box frame 128. A second gasket 130 seals the second bushing end 126 to the box frame 132. As explained in more detail below, upon an application of pneumatic pressure within the chamber 1 14, to the molten alloy material flows upward through the riser 1 16 to enter the feeder box 132.

[0019] The feeder box 132 is configured as a universal adapter to control the distribution of molten ahoy materia] received from the furnace 112 to the cavity 156 of the die assembly 152. More specifically, the feeder box 132 is configured to receive molten alloy material from the riser 116 of the furnace 112 and deliver the molten alloy material to the cavity 156 defined by the die assembly 152 through multiple gates 135, 148, As such, during low pressure die casting (LPDC), the feeder box 132 allows the cavity' 156 of the corresponding die assembly 152 to be filled more uniformly⁷ and quickly than would be achieved by filling from a single central gate. By filling the cavity' 156 via multiple gates 135, 148, the entire cavity 156 is filled more at a more even rate than is possible from a single gate, while also maintaining a lower pressure. Low pressure, and thus low velocity, prevents the oxide formation on the alloy and air entrapment that is typically associated with high pressure systems. [0020] Referring between Figures 2, 3, and 6, the feeder box 132 includes a frame 128 extending between an upper box surface 146 and a lower box surface 147. In one nonlimiting embodiment, the feeder box 132 is formed from ceramic material that is durable enough to withstand the heat associated with the molten alloy material. Alternatively, the feeder box 132 is formed from a metal alloy with a higher melt temperature than the alloy used to form the wheel 10. The feeder box 132 defines a molten metal distribution or runner system 136 (as used interchangeably throughout) having a generally candelabra shape that extends between the upper box surface 146 and the lower box surface 147. More specifically, the distribution system 136 defines a fluid connection between an intake or inlet opening 155 defined in the lower box surface 147 and a plurality of outlet openings 144, 148 (e.g., a central outlet opening 144 and a pair of side outlet openings 148) defines in the upper box surface 146. The feeder box 132 is configured to receive the molten alloy material from the riser 116 at the intake opening 155, and deliver the molten alloy material to the cavity⁷ 156 of the die assembly 152 via the respective outlet openings 144, 148

[0021] The distribution system 136 includes a central runner 138 and a pair of side runners 142 that branch away from the central runner 138. The central runner 138, which is illustrated as extending linearly between the intake opening 155 in the lower box surface 147 and the central outlet opening 144 in the upper box surface 146. Likewise, the pair of side runners 142 branch upwardly away from central runner 138, at an angle, to define an intersection 154. The side runners 142 define a first section 143 and a second section 145 interconnected by an elbow 141. More specifically, the first section 143 extends between the central runner 138 and the elbow 141. The first section 143 of each side runner 142 extends from the central runner 138 defining a V-shaped angle with the central runner 138. The elbows 141 are configured to change a direction of the side runners 142, such that the second section 145 of each side runner 142 and the central runner 138 extend in generally spaced and parallel relationship to one another. The first sections 143 of the side runners 142 are oriented at the V-shaped angles relative to the central runner 138 to minimize an exposed free surface of the molten alloy. Minimizing the exposed free surface of molten alloy minimizes formation of oxides in the molten alloy as it flows through the feeder box 132. [0022] The feeder box 132 is configured to connect to the riser 116, at the intake opening 155, via a coupling conduit 140 defined by a coupling bushing 120. In an alternative embodiment, the coupling conduit 140 takes the form of a tubular sleave that is received by the coupling bushing 120. In either embodiment, the coupling bushing 120 enables the feeder box 132 to be interchanged with a conventional furnace 112 without modification of the furnace.

[0023] The die assembly 152 defines at least one cavity 156 configured for receiving molten alloy material from the furnace 112, via the heater box 132. More specifically, the die casting assembly 152 includes a mold 134a (e.g., a wheel mold and the like). The mold 134a includes a top core 134b and a face core 134c that combine to define at least one cavity 156 therebetween. The face core 134c defines a plurality of gates 135, 148. As illustrated in Figure 2, the exemplary die assembly 152 includes two side gates 135 radially disposed relative to the central gate 148 at axis A. Each gate 44 opens to the cavity 156 of the mold 134a. Each gate 135, 148 is oriented to fluidly couple with the corresponding one of the outlet openings 144, 148 defined in the upper box surface 146 of the feeder box 132.

[0024] The die casting system 1 10 is configured to perform low pressure die casting (LPDC) while still increasing flow rate of molten alloy between the furnace 112 and the die for die cavity 156. LPDC involves filling the die casting assembly 152 with molten alloy material (e.g., molten alloy metal and the like) in an upwardly direction into the cavity 156 of the die assembly 152 while maintaining low feed pressure. In one non-limiting embodiment, the pressure is less than 1 atmosphere (atm) of pressure. The LPDC process generates improved alloy solidification due to continuous filling of the die cavity during wheel formation (i.e., shrinking phase) with reduced oxide formation and porosity while providing more uniform and even parallel alloy dendrite formation throughout the wheel. [0025] As known to those of skill in the art, pressure is adjusted over time in multiple stages, e.g., a first pressure stage, a second pressure stage, and a third pressure stage. The pressure at each pressure stage is maintained below 1 atm. As pneumatic pressure is initially applied into the furnace chamber 114 at the first pressure stage, molten alloy material is pushed up through the riser 116, through the conduit 140 of the feeder box 132 into the inlet opening 155. Once the material has reached the inlet opening 155, the pressure is decreased at the second pressure stage to minimize or otherwise prevent turbulent flow of the molten alloy material flowing through the distribution system 136, between the inlet opening 155 and each of the outlet openings 144, 148, and throughout the die cavity' 156. More specifically, pressure at the second pressure stage is maintained to prevent turbulence inside the die cavity 156 until the cavity 156 is filled with molten alloy material. Once the die cavity 156 is filled, the pressure may be again increased during the third pressure stage to hold the alloy material in place within the die cavity 156 of the mold 134a during solidification.

[0026] It should be understood by those of skill in the art that two, three, or more side runners 142 may be included to provide desired flow rate of molten alloy into the wheel cavity 156. It should also be understood by those of skill in the art that the diameter of the side runners 142 and the central runner 138 may be individually adjusted, either increased or decreased, as necessary' to control the inlet velocity and flow rate of the molten alloy metal into various portions of the cavity' 156. The side runners 142 do not have to match the size of the central runner 138, and the side runners 142 may' each have a different diameter if necessary. Diameters of each of the runners 138, 142 are determined to provide an optimal velocity and flow rate of molten alloy to the different areas of the wheel cavity 156 defined by the die assembly 152.

[0027] The gates 135 that are interconnected with the side runners 142 and the central runner 138 to provide a flow of molten alloy to a ri m cavity 158 of the wheel cavity 156. As such, the side gates 144 are spaced radially outwardly from the central gate 148. The central gate 148 provides molten alloy to a face cavity 160 of the wheel cavity 156. Therefore, a flow of molten alloy is simultaneously injected into both the rim cavity' 158 and the face cavity⁷ 158. Significantly, the rim element 12 and the hub 14 of the wheel 10 are formed simultaneously by way of the inventive runners 138, 142 of the present application allowing for more consistent dendrite formation throughout the wheel, something not previously achievable.

[0028] With reference to Figure 3-6, the feeder box 132 includes a base 162 that is affixed to the support frame 128 using fasteners received through fastener apertures 166. The feeder box 132 includes opposing side walls 168 and opposing end walls 170. A plurality of heating elements 172 extend inside the feeder box 132 to maintain consistent temperature of the molten alloy flowing through the runner system 136 into the wheel cavity 156. Heating element connectors 174 protrade through the end walls 170 and are interconnected with a heating system to continuously provide heat to the feeder box 132. Therefore, consistent heat is provided to the feeder box 132. The heating elements 172 may be either fluidic or electrical. Still further, the heating elements 172 may take the form of thermal rods adapted to radiate heat. Therefore, in a further embodiment, the heating element 172 takes the form of a thermal rod or plurality⁷ of thermal rods that radiate heat into the feeder box 132. In similar manner, the heater rods maintain constant temperature of the molten alloy inside the distribution system 136 and also prevent the molten alloy from solidifying should the system 110 become dormant by transfer of heat through the ceramic to the distribution system 136.

[0029] In one embodiment, the feeder box 132 includes a control system with a thermocouple, or a plurality of thermocouples located proximate the runner system 136 to monitor temperature of the molten alloy. Further, the thermocouples may be in contact with the distribution system 136. In either embodiment the thermocouples provide temperature measurement to a controller that adjusts the temperature of the heating elements 172 for maintaining temperature of the molten alloy within a tightly controlled range further improving quality' of a resultant vehicle wheel. [0030] In one embodiment, the feeder box 132 is removably affixed to the wheel die assembly 152 so that wheels 10 having a same or similar rim diameter may be cast implementing the same feeder box 132, In this example, the face cavity 160 may take a different configuration for an alternative wheel appearance while the rim cavity 158 remains substantially the same. Alternatively, each feeder box 132 is unique to accommodate different size wheel molds 134a according to specific wheel rim sizes (i.e., 16", 17", 18", 19", 20", 22” etc.) and the feeder box 132 and wheel mold 134a can be independently removed from the low-pressure furnace. Therefore, it should be understood that the die assembly 152, in one embodiment is removable without removing the feeder box 132 from the furnace 1 12. Alternatively, the feeder box 132 is paired with a particular die assembly 152 so that the die assembly 152 and the feeder box 132 are simultaneously removed from the furnace 1 12 merely by disconnecting the feeder box 132 from the furnace 1 12.

[0031 ] As set forth herein above, in one embodiment, the feeder box 132 is formed from a metallic containment structure with ceramic material disposed inside the metallic structure to withstand the heat generated inside the furnace chamber 114, The runner system 136 is defined by a castable or otherwise formable ceramic. Alternatively, the runner system 136 is formed of heat resistant tubing and encased in castable ceramic material. In a similar manner, the heating elements 172 may also be encased in ceramic. In one embodiment, the feeder box 132 is 3D printed to form the internal channels defining the runner system 136 and the heating elements 172. Alternatively, the feeder box 132 is formed by casting a castable ceramic material. Still further, the ceramic material may be formed in blocks or bricks that encase and hold the runner system 136 and the heating elements 172. Still further, the heating elements may take the form of an electric heating blanket encasing the feeder box 132.

[0032] As alluded to above, consistent heating and improved flow rate of the molten alloy, in addition to the ability to deliver molten metal directly to the ends of the wheel spokes, also provides significant improvements to the mechanical properties of the vehicle wheels formed using the system 1 10 of the present disclosure. For example, prior art systems that feed molten alloy directly from a furnace through a single central runner 142 results in radial flow of alloy through the face cavity to the rim cavity⁷. This results in inconsistent cooling of the alloy and non-directional dendrite formation, which is known to diminish mechanical properties of an alloy casting. The system 1 10 of the present disclosure provide rapid fill of, for example, the rim cavity 158 when the molten alloy is at a desirable temperature and flow properties providing enhanced and optimal dendrite formation that is disposed in a consistent orientation, i.e., a linear grain orientation throughout and particularly in the wheel spokes 22. This optimal formation provides improved mechanical properties allowing for decreased wheel 10 thickness, particularly in the wheel spokes.

[0033] Additional mechanical improvements are realized in the spokes of the wheel 10. Because molten alloy need not flow⁷ through the spokes 22 to the rim element 12, the molten alloy forming the spokes 22 can be solidified in a more rapid and consistent manner providing the enhanced dendritic formation. Further, an increased solidification rate is realized in the spokes 22 and hub 14 because the face cavity 160 is not being used as a primary conduit for transfer of molten alloy to the rim cavity⁷ 158.

[0034] Thus, forced cooling can be added to the spoke portion of the face cavity⁷ 160 to further accelerate solidification. Therefore, thickness of the spokes 22 may also be reduced taking advantage of the improved mechanical properties reducing overall mass of the wheel 10 through improved mechanical properties.

[0035] Additional improvements are realized in cycle time. Through improved and more uniform flow of molten alloy into the rim cavity 158, time required to fill the entire wheel cavity 156, and the time to solidify the wheel casting, is reduced significantly. It is believed that production rate is increased by between 150% to 100% over conventional wheel casting techniques, all while significantly improving quality.

[0036] The disclosure has been described in an illustrative manner; many modifications and variations of the present disclosure are possible, including removal of impurities from the molten metal. It is therefore to be understood that within the specification, the reference numerals are merely for convenience, and are not to be in any way limiting, and that the disclosure may be practiced otherwise than is specifically described. Therefore, the disclosure can be practiced otherwise than is specifically described within the scope of the stated claims following this first disclosed embodiment.

Claims

CLAIMS What is claimed is:

1. A system for manufacturing a cast alloy wheel, comprising: a mold defining a die cavity being configured to form the alloy wheel including a face portion and a rim portion; a furnace for heating and maintaining the alloy material at a molten state; and a feeder box interconnecting said furnace to said mold thereby providing molten alloy to said die cavity and said feeder box defining a gate system with a central runner for providing molten alloy to said face portion of said die cavity' and a plurality of side runners for providing a molten alloy to said rim portion of said die cavity.

2. The system set forth in claim 1 , wherein said side runners include side outlet openings for transferring molten alloy directly into said rim portion of said die cavity.

3. The system set forth in claim 1 , wherein said feeder box includes a heating element for maintaining temperature of said molten alloy within a predetermined range thereby maintain consistent flow rate of the molten alloy into said die cavity.

4. The system set forth in claim 1, wherein said feeder box comprises a castable, or formable ceramic thereby forming a monolithic feedbox and gate system.

5. The system set forth in claim 1 , wherein said feeder box is removably interconnected to said mold and said furnace thereby being interchangeable with at least one of said mold and said furnace.

6. The system set forth in claim 1, wherein said heating elements comprises a plurality of heat members extending through said feeder box on opposing sides of said gate system.

7. The system set forth in claim 1, wherein said central runner and said plurality of side runners are configured for providing substantially equivalent flow rates of molten alloy to said die cavity' at different locations of said die cavity.

8. The system set forth in claim 1, wherein said central runner and said plurality of side runners receive molten alloy⁷ material through a feed connecter being coaxial with said central runner.

9. The system set forth in claim 1, wherein each of said plurality of side runners is disposed radially outwardly of said die cavity.

10. The system set forth in claim 1 , wherein said feeder box is interconnected to a mold frame being releasably engaged with said mold.

1 1. A feeder box connection between a die assembly defining a cavity to form an alloy wheel and a furnace for delivering a molten alloy⁷ material, the feeder box comprising: a frame extending between an upper surface and a lower surface; a distribution system opening between an inlet opening in the lower surface and a plurality⁷ of outlet openings in the upper surface to provide fluid communication between the inlet opening and each of the outlet openings; wherein the inlet opening is configured for attachment to a riser of the furnace and each of the outlet openings are configured to be fluidly connected to a respective gate of the die cavity; wherein the feeder box is configured to receive the molten alloy material from the riser at the intake opening and deliver the molten allow material to the cavity⁷ of the die assembly via the respective outlet openings.

12. The feeder box of claim 1 1 wherein the distribution system includes a central runner and a pair of side runners extending in branched relationship from the central runner.

13. The feeder box of claim 12, wherein the distribution system presents a generally candelabra shape.

14. The feeder box of claim 1 1 , wherein the central runner extends linearly between the intake opening in the lower surface and the central outlet opening in the upper box surface; and wherein each of said side runners include a first section, a second section, and an elbow defined therebetween; and wherein said central runner and said second sections of each of said second runners extend in spaced and generally parallel relationship to one another.

15. The feeder box of claim 11, wherein said feeder box includes a heating element for maintaining temperature of the molten alloy material within a predetermined range to thereby maintain consistent flow rate of the molten alloy into said die cavity.

16. The feeder box of claim 11 , wherein said feeder box comprises a castable ceramic thereby forming a monolithic feedbox and gate system.

17. The feeder box of claim 11, wherein said feeder box is configured to be removably linked to said die assembly and said furnace thereby being interchangeable with at least one of said die assembly and said furnace.

18. The feeder box of claim 11, wherein said heating elements comprise a plurality of heating elements extending through said feeder box on opposing sides of said distribution system.

19. The feeder box of claim 1 1 , wherein said central axial runner and said plural ity' of side runners are configured for providing substantially equivalent flow rates of molten alloy to said die cavity.

20. The feeder fox of claim 11 , wherein said central runner and said pair of side runners are configured to receive molten alloy material through a feed connecter being coaxial with the central runner.