System and method for making a crankshaft from a replacement material

Abstract

A crankshaft for an internal combustion engine is provided. The crankshaft includes at least four main journals aligned on a crankshaft rotation axis defining a centerline. The crankshaft further includes at least three pin journals. Each pin journal is disposed about a respective pin journal axis and positioned between the main journals. Each of the pin journals is coupled to a pair of crank arms. Each pair of crank arms is coupled to a respective main journal. Each of the main journals, pin journals, and crank arms is made of a first metallic material. Each crank arm has an overmolded counterweight metallurgically bonded thereto. Each counterweight is disposed opposite the respective pin journal relative to the centerline to achieve balance and stability. Each counterweight is made of a second metallic material. The crankshaft has a weight ratio of the second metallic material to the first metallic material between 0.20 to 0.50.

Description

Technical Field

[0001] This disclosure relates to crankshafts, and more specifically to systems and methods for manufacturing crankshafts with alternative materials for use in vehicles. Background Technology

[0002] A crankshaft is a vehicle component that enables the conversion between reciprocating and rotary motion. Crankshafts can be manufactured in various ways, such as by forming from blanks, forging, and casting. Currently, improvements in crankshaft manufacturing can lead to quality efficiency and cost savings. Summary of the Invention

[0003] Therefore, while current crankshafts achieve their intended purpose, a new and improved system and method are needed for manufacturing vehicle crankshafts. Based on the embodiments and examples discussed herein, this disclosure provides a system and method for manufacturing vehicle crankshafts with alternative materials, resulting in quality efficiency and weight savings. Furthermore, it achieves manufacturing cost savings.

[0004] According to one aspect of this disclosure, a crankshaft for an internal combustion engine is provided. The crankshaft includes at least four main journals aligned on a crankshaft rotation axis defining a centerline. The crankshaft further includes at least three pivot journals.

[0005] In this respect, each journal pin is disposed and positioned between the main journals around its respective journal pin axis. Furthermore, each of the respective journal pin axes is oriented parallel to and radially spaced from the crankshaft axis. Additionally, each journal pin is coupled to a pair of crank arms for force transmission between the journal pin and the pair of crank arms. Further, each pair of crank arms is coupled to a corresponding main journal for torque transmission between the pair of crank arms and the main journal. Moreover, each of the main journals, journal pins, and crank arms is made of a first metallic material.

[0006] Furthermore, each crank arm has a metallurgically bonded, molded counterweight. Additionally, each counterweight is positioned relative to the centerline and the corresponding journal pin to achieve balance and stability. Furthermore, each counterweight is made of a second metal material. The second metal material is denser than the first metal material to achieve mass efficiency. Moreover, the crankshaft has a weight ratio of the second metal material to the first metal material between 0.20 and 0.50.

[0007] In one embodiment, the first metallic material comprises a ductile iron alloy and a steel alloy, and the second metallic material comprises a steel alloy and tungsten. In another embodiment, the weight ratio of the second metallic material to the first metallic material is 0.36.

[0008] In another embodiment, for each counterweight positioned relative to the centerline and the corresponding journal, the crank arm has a counterweight-to-crank arm weight ratio between 2.0 and 3.0. In yet another embodiment, each overmolded counterweight includes one of a full counterweight and a partial counterweight. The full counterweight has more mass than the partial counterweight. In yet another embodiment, the overmolded counterweight includes a full counterweight-to-partial counterweight weight ratio between 1.5 and 1.7.

[0009] In one embodiment, the ductile iron alloy comprises 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), and 0 to 0.002 wt% cerium (Ce).

[0010] In another embodiment, the ductile iron alloy has a spheroidization rate greater than 85%. In this embodiment, the ductile iron alloy has a Young's modulus in the range of 175 to 195 GPa. Furthermore, the ductile iron alloy has a casting ultimate tensile strength in the range of 750 to 950 MPa.

[0011] In yet another embodiment, the crankshaft further includes an outer coating composed of one of a nickel (Ni) and a copper (Cu) compound to promote metallurgical bonding between the first and second metallic materials. In one embodiment, the outer coating has a thickness of 1 micrometer to 10 micrometers.

[0012] According to another aspect of this disclosure, a system for manufacturing a crankshaft having an alternative material is provided. The system includes a molding unit arranged to form a reverse sand casting mold for the crankshaft. The mold includes at least one molding cavity with a pattern having dimensions of the crankshaft.

[0013] In this respect, the crankshaft is arranged or designed to include at least four main journals and at least three pin journals aligned on a crankshaft rotation axis defining a centerline. Each pin journal is disposed about a corresponding pin journal axis and positioned between the main journals. Furthermore, each of the corresponding pin journal axes is oriented parallel to and radially spaced from the crankshaft axis. Additionally, each of the pin journals is coupled to a pair of crank arms for force transmission between the pin journal and the pair of crank arms. Further, each pair of crank arms is coupled to a corresponding main journal for torque transmission between the pair of crank arms and the main journal. Additionally, each of the main journals, pin journals, and crank arms is arranged to be made of a first metallic material.

[0014] In this respect, at least one of the crank arms is arranged to have a molded counterweight. The molded counterweight is arranged to be molded by and metallurgically bonded to at least one of the crank arms. Furthermore, each molded counterweight is arranged to be positioned relative to the centerline and opposite to the corresponding journal pin to achieve balance and stability. Further, each molded counterweight is arranged to be made of a second metal material. The second metal material is arranged to be denser than the first metal material to achieve mass efficiency. Additionally, the molded counterweight is disposed in at least one molded cavity.

[0015] The system further includes a furnace for melting a first metallic material between 1400°C and 1600°C to define the molten metallic material. Furthermore, the system further includes a gating mechanism for pouring the molten metallic material into a sand casting mold between 1350°C and 1450°C, such that at least one overmolded counterweight is overmolded by the molten metallic material. Additionally, the system further includes a cooling zone for solidifying the molten metallic material in the sand casting mold, such that at least one of the crank arms forms an overmolded counterweight. The at least one overmolded counterweight is arranged to metallurgically bond to at least one of the crank arms defining the crankshaft at approximately 450°C.

[0016] In this respect, the system further includes a separation unit for separating the crankshaft from the anti-sand casting mold. Furthermore, the crankshaft has a weight ratio of a second metal material to a first metal material between 0.20 and 0.50. Additionally, the system includes a controller that communicates with the molding unit, the furnace, the gating mechanism, and the separation unit. Furthermore, the controller is configured to control the molding unit, the furnace, the gating mechanism, and the separation unit. Additionally, the system includes a power source configured to provide power to the molding unit, the furnace, the gating mechanism, the separation unit, and the controller.

[0017] In one embodiment, the first metallic material comprises a ductile iron alloy and a steel alloy, and the second metallic material comprises a steel alloy and tungsten. In another embodiment, for each counterweight disposed opposite to the corresponding pin journal relative to the centerline, the crank arm has a counterweight-to-crank arm weight ratio of 2.5. In yet another embodiment, the overmolded counterweight comprises a full counterweight and a partial counterweight. The full counterweight has more mass than the partial counterweight, and the overmolded counterweight comprises a full counterweight-to-partial counterweight weight ratio of 1.6.

[0018] In another embodiment, the ductile iron alloy comprises 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), and 0 to 0.002 wt% cerium (Ce).

[0019] In yet another embodiment, the ductile iron alloy has a spheroidization rate of greater than 85%, a Young's modulus in the range of 175 to 195 GPa, and a casting ultimate tensile strength in the range of 750 to 950 MPa.

[0020] According to another aspect of this disclosure, a method for manufacturing a crankshaft having an alternative material is provided. In this aspect, the method includes providing a reverse sand casting mold for the crankshaft. The crankshaft includes at least four main journals aligned on a crankshaft rotation axis defining a centerline. The crankshaft further includes at least three pin journals.

[0021] In this respect, each journal pin is disposed and positioned between the main journals around its respective journal pin axis. Furthermore, each of the respective journal pin axes is oriented parallel to and radially spaced from the crankshaft axis. Additionally, each journal pin is coupled to a pair of crank arms for force transmission between the journal pin and the pair of crank arms. Further, each pair of crank arms is coupled to a corresponding main journal for torque transmission between the pair of crank arms and the main journal. Moreover, each of the main journals, journal pins, and crank arms is arranged to be made of a first metallic material.

[0022] In this respect, at least one of the crank arms is arranged to have a molded counterweight. Furthermore, the molded counterweight is arranged to be molded by and metallurgically bonded to at least one of the crank arms. Each molded counterweight is arranged to be positioned relative to the centerline and opposite to the corresponding journal pin to achieve balance and stability. Further, each molded counterweight is arranged to be made of a second metal material. The second metal material is arranged to be denser than the first metal material to achieve mass efficiency.

[0023] In this respect, the method further includes placing at least one overmolded counterweight in a crankshaft mold and melting a first metallic material to define the molten metallic material. The method further includes pouring the molten metallic material into a reverse sand casting mold such that at least one overmolded counterweight is overmolded by the molten metallic material.

[0024] In this respect, the method further includes solidifying the molten metal material in the anti-sand casting mold, such that at least one of the crank arms is formed as an overmolded counterweight. The at least one overmolded counterweight is metallurgically bonded to at least one of the crank arms defining the crankshaft. The method further includes separating the crankshaft from the anti-sand casting mold. The crankshaft has a weight ratio of a second metal material to a first metal material between 0.20 and 0.50.

[0025] In one example, the first metallic material comprises a ductile iron alloy and a steel alloy, and the second metallic material comprises a steel alloy and tungsten. In another example, the weight ratio of the second metallic material to the first metallic material is 0.36.

[0026] In another example, the ductile iron alloy comprises 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), and 0 to 0.002 wt% cerium (Ce).

[0027] Other applicable areas will become apparent from the description provided herein. It should be understood that the descriptions and specific examples are intended for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0028] The present invention also includes the following technical solutions.

[0029] Technical Solution 1. A crankshaft for an internal combustion engine, the crankshaft comprising:

[0030] At least four main journals aligned on the crankshaft rotation axis defining the center line; and

[0031] At least three journals are provided, each journal being disposed around a corresponding journal axis and positioned between main journals. Each of the corresponding journal axes is oriented parallel to and radially spaced from the crankshaft axis. Each journal is connected to a pair of crank arms for force transmission between the journal and the pair of crank arms. Each pair of crank arms is connected to a corresponding main journal for torque transmission between the pair of crank arms and the main journal. Each of the main journals, journals, and crank arms is made of a first metallic material.

[0032] Each crank arm has a metallurgically bonded, molded counterweight, each counterweight being positioned relative to the centerline and the corresponding journal pin to achieve balance and stability, each counterweight being made of a second metal material that is denser than the first metal material to achieve mass efficiency, and the crankshaft having a weight ratio of the second metal material to the first metal material between 0.20 and 0.50.

[0033] Technical Solution 2. The crankshaft according to Technical Solution 1, wherein the first metallic material comprises ductile iron alloy and steel alloy, and wherein the second metallic material comprises steel alloy and tungsten.

[0034] Technical Solution 3. The crankshaft according to Technical Solution 1, wherein the weight ratio of the second metal material to the first metal material is 0.36.

[0035] Technical Solution 4. The crankshaft according to Technical Solution 1, wherein, for each counterweight disposed relative to the centerline and the corresponding journal, the crank arm has a counterweight to crank arm weight ratio between 2.0 and 3.0.

[0036] Technical Solution 5. The crankshaft according to Technical Solution 1, wherein each molded counterweight includes one of a complete counterweight and a partial counterweight, wherein the complete counterweight has more mass than the partial counterweight.

[0037] Technical Solution 6. The crankshaft according to Technical Solution 5, wherein the overmolded counterweight comprises a full counterweight to partial counterweight weight ratio between 1.5 and 1.7.

[0038] Technical Solution 7. The crankshaft according to Technical Solution 1, wherein the ductile iron alloy comprises 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), and 0 to 0.002 wt% cerium (Ce).

[0039] Technical Solution 8. The crankshaft according to Technical Solution 2, wherein the ductile iron alloy has a spheroidization rate of greater than 85%, a Young's modulus in the range of 175 to 195 GPa, and a casting ultimate tensile strength in the range of 750 to 950 MPa.

[0040] Technical Solution 9. The crankshaft according to Technical Solution 2, wherein the crankshaft further comprises an outer coating composed of one of nickel (Ni) and copper (Cu) compounds to promote metallurgical bonding between the first metal material and the second metal material.

[0041] Technical Solution 10. The crankshaft according to Technical Solution 9, wherein the outer coating has a thickness of 1 micrometer to 10 micrometers.

[0042] Technical Solution 11. A system for manufacturing crankshafts with alternative materials, the system comprising:

[0043] A molding unit arranged to form a reverse sand casting mold for a crankshaft, the mold comprising at least one molding cavity having a pattern having dimensions of a crankshaft, the crankshaft comprising:

[0044] At least four main journals aligned on the crankshaft rotation axis defining the center line; and

[0045] At least three journals are provided, each journal being disposed around a corresponding journal axis and positioned between main journals. Each of the corresponding journal axes is oriented parallel to and radially spaced from the crankshaft axis. Each journal is connected to a pair of crank arms for force transmission between the journal and the pair of crank arms. Each pair of crank arms is connected to a corresponding main journal for torque transmission between the pair of crank arms and the main journal. Each of the main journals, journals, and crank arms is arranged to be made of a first metallic material.

[0046] At least one of the crank arms is arranged to have a molded counterweight, the molded counterweight being arranged to be molded and metallurgically bonded to the at least one of the crank arms, each molded counterweight being arranged to be positioned relative to the centerline and opposite to the corresponding journal pin for balance and stability, each molded counterweight being made of a second metal material, the second metal material being arranged to be denser than the first metal material for mass efficiency.

[0047] The molded counterweight is placed in at least one molded cavity;

[0048] A furnace for melting a first metallic material between 1400 degrees Celsius (°C) and 1600 degrees Celsius to define the molten metallic material;

[0049] A gating mechanism for pouring molten metal material into a reverse sand casting mold between 1350°C and 1450°C, such that at least one overmolded counterweight is overmolded by the molten metal material.

[0050] A cooling zone for solidifying molten metal material in a reverse sand casting mold, such that at least one of the crank arms is formed as an overmolded counterweight, the at least one overmolded counterweight being metallurgically bonded to at least one of the crank arms defining the crankshaft at about 450°C.

[0051] A separation unit for separating the crankshaft from the reverse sand casting mold, wherein the crankshaft has a weight ratio of a second metal material to a first metal material between 0.20 and 0.50;

[0052] A controller that communicates with the molding unit, furnace, casting mechanism, and slitting unit, the controller being configured to control the molding unit, furnace, casting mechanism, and slitting unit; and

[0053] A power source configured to provide power to the molding unit, furnace, casting mechanism, separation unit, and controller.

[0054] Technical Solution 12. The system according to Technical Solution 11, wherein the first metallic material comprises ductile iron alloy and steel alloy, and wherein the second metallic material comprises steel alloy and tungsten.

[0055] Technical Solution 13. The system according to Technical Solution 11, wherein, for each counterweight disposed relative to the centerline and the corresponding pin journal, the crank arm has a counterweight to crank arm weight ratio of 2.5.

[0056] Technical Solution 14. The system according to Technical Solution 11, wherein the overmolded counterweight includes one of a complete counterweight and a partial counterweight, wherein the complete counterweight has more mass than the partial counterweight, and wherein the overmolded counterweight includes a weight ratio of 1.6 between the complete counterweight and the partial counterweight.

[0057] Technical Solution 15. The system according to Technical Solution 11, wherein the ductile iron alloy comprises 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), and 0 to 0.002 wt% cerium (Ce).

[0058] Technical Solution 16. The system according to Technical Solution 12, wherein the ductile iron alloy has a spheroidization rate greater than 85%, a Young's modulus in the range of 175 to 195 GPa, and a casting ultimate tensile strength in the range of 750 to 950 MPa.

[0059] Technical Solution 17. A method for manufacturing a crankshaft with an alternative material, the method comprising:

[0060] A reverse sand casting mold is provided for a crankshaft, the crankshaft comprising:

[0061] At least four main journals aligned on the crankshaft rotation axis defining the center line; and

[0062] At least three journals are provided, each journal being disposed around a corresponding journal axis and positioned between main journals. Each of the corresponding journal axes is oriented parallel to and radially spaced from the crankshaft axis. Each journal is connected to a pair of crank arms for force transmission between the journal and the pair of crank arms. Each pair of crank arms is connected to a corresponding main journal for torque transmission between the pair of crank arms and the main journal. Each of the main journals, journals, and crank arms is arranged to be made of a first metallic material.

[0063] At least one of the crank arms is arranged to have a molded counterweight, the molded counterweight being arranged to be molded by and metallurgically bonded to the at least one of the crank arms, each molded counterweight being arranged to be positioned relative to the centerline and opposite to the corresponding journal to achieve balance and stability, each molded counterweight being arranged to be made of a second metal material, the second metal material being arranged to be denser than the first metal material to achieve mass efficiency;

[0064] At least one overmolded counterweight is placed in the crankshaft's reverse mold;

[0065] The first metallic material is melted between 1400 degrees Celsius (°C) and 1600 degrees Celsius to define the molten metallic material;

[0066] Molten metal material is poured into a reverse sand casting mold between 1350°C and 1450°C, such that at least one overmolded counterweight is overmolded by the molten metal material.

[0067] The molten metal material in the reverse sand casting mold is solidified, such that at least one of the crank arms is formed as an overmolded counterweight, the at least one overmolded counterweight being metallurgically bonded to at least one of the crank arms defining the crankshaft; and

[0068] The crankshaft is separated from the reverse sand casting mold, and the crankshaft has a weight ratio of second metal material to first metal material between 0.20 and 0.50.

[0069] Technical Solution 18. The crankshaft according to Technical Solution 17, wherein the first metallic material comprises ductile iron alloy and steel alloy, and wherein the second metallic material comprises steel alloy and tungsten.

[0070] Technical Solution 19. The crankshaft according to Technical Solution 17, wherein the weight ratio of the second metal material to the first metal material is 0.36.

[0071] Technical Solution 20. The method according to Technical Solution 18, wherein the ductile iron alloy comprises 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), and 0 to 0.002 wt% cerium (Ce). Attached Figure Description

[0072] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way.

[0073] Figure 1 This is a schematic diagram of a system for manufacturing a crankshaft with alternative materials according to an embodiment of the present disclosure.

[0074] Figure 2A According to one embodiment Figure 1 A perspective view of the crankshaft made by the system.

[0075] Figure 2B yes Figure 2A An enlarged view of the crankshaft.

[0076] Figure 2C This is a perspective view of a counterweight molded according to another embodiment of the present disclosure.

[0077] Figure 2D yes Figure 2C The counterweight is molded and shaped along a 2D-2D cross-sectional view.

[0078] Figure 3A According to another embodiment Figure 1 A perspective view of the crankshaft made by the system.

[0079] Figure 3B yes Figure 3A A cross-sectional view of the crankshaft taken along line 3B-3B.

[0080] Figure 3C yes Figure 3A A cross-sectional view of the crankshaft taken along line 3C-3C.

[0081] Figure 4 This is based on an example of the disclosure. Figure 1 A flowchart of the system's method for manufacturing crankshafts. Detailed Implementation

[0082] The following description is exemplary in nature and is not intended to limit this disclosure, application, or use.

[0083] Figure 1 A system 10 for manufacturing a crankshaft with alternative materials according to one embodiment of the present disclosure is illustrated. As shown, system 10 includes a molding unit 12 arranged to form a reverse sand casting mold for the crankshaft. The mold includes at least one molding cavity, preferably multiple molding cavities, to define the crankshaft to be cast. The molding unit 12 is arranged to form a mold with a pattern (not shown) having dimensions of the crankshaft. In one example, the mold has a pattern made of virgin sand or chemically bonded sand. A core assembly can then be placed within the mold to further define the size or structure of the pattern. It should be understood that the mold can be made by any other suitable means without departing from the spirit or scope of the present disclosure.

[0084] refer to Figure 2A and Figure 2BAs an example, the crankshaft 110 is designed or arranged to include at least four main journals 112 (here, five main journals) and at least three pin journals 120 (here, four pin journals) aligned on a crankshaft rotation axis 114 defining a centerline 116. In this embodiment, each pin journal 120 is solid and is disposed and positioned between the main journals 112 about a corresponding pin journal axis 122. Furthermore, each pin journal axis 122 is oriented parallel to and radially spaced from the crankshaft axis 114. Additionally, each of the pin journals 120 is coupled to a pair of crank arms 124 for force transmission between the pin journal 120 and the pair of crank arms 124. Further, each pair of crank arms 124 is coupled to a corresponding main journal 112 for transmitting torque between the pair of crank arms 124 and the main journal 112. Additionally, each of the main journals 112, pin journals 120, and crank arms 124 is made of a first metallic material.

[0085] like Figure 2A and Figure 2B As illustrated by way of example, at least one of the crank arms 124 is arranged to have a molded counterweight 130. During the manufacture of the crankshaft 110, the molded counterweight 130 is molded and metallurgically bonded to at least one of the crank arms 124. Figure 2B As shown, each counterweight 130 includes a recessed portion from which locking mechanisms 132 or more locking mechanisms (such as studs) extend. Since each counterweight 130 is overmolded and metallurgically bonded to at least one of the crank arms, the locking mechanism provides further attachment to the crank arm.

[0086] Furthermore, each overmolded counterweight 130 is positioned relative to the centerline 116 and the corresponding pivot journal 120 to achieve balance and stability. Further, each overmolded counterweight 130 is made of a second metal material. The second metal material is denser than the first metal material to achieve mass efficiency. As will be discussed in more detail below, during the manufacture of the crankshaft 110 with the alternative material, the overmolded counterweight 130 is placed in at least one molding cavity of the anti-sand casting mold during the realization of system 10.

[0087] In one embodiment, the first metallic material comprises a ductile iron alloy and a steel alloy, and the second metallic material comprises a steel alloy and tungsten. In this embodiment, for each counterweight positioned relative to the centerline and the corresponding journal, the crank arm 124 has a counterweight-to-crank arm weight ratio of 2.5. Preferably, the ductile iron alloy has a spheroidization rate greater than 85%, a Young's modulus in the range of 175 to 195 GPa, and a casting ultimate tensile strength in the range of 750 to 950 MPa.

[0088] In one embodiment, the overmolded weight 130 may include one of a full weight 134 and a partial weight 136. In this embodiment, the full weight 134 has more mass than the partial weight 136, and the overmolded weight comprises a full weight to partial weight weight ratio of 1.6.

[0089] Figure 2C and Figure 2D The illustration shows an overmolded counterweight 140, according to another embodiment of the present disclosure, which is overmolded from a first metallic material during the casting or molding of the crankshaft. During crankshaft manufacturing, the overmolded counterweight 140 is overmolded from at least one of the crank arms and metallurgically bonded thereto. Figure 2C and Figure 2D As shown, each counterweight 140 includes a recessed portion thereon, on which an open cavity 142 is formed. When each counterweight 140 is overmolded and metallurgically attached to at least one of the crank arms, the open cavity can act as a locking mechanism. Thus, the locking mechanism provides further attachment to the crank arm.

[0090] Come back for reference Figure 1 The system 10 further includes a furnace 14 for melting a first metallic material (e.g., a ductile iron alloy) between 1400 degrees Celsius (°C) and 1600 degrees Celsius to define the molten metallic material. In one embodiment, the furnace 14 may contain a ductile iron alloy. The furnace 14 may be an electric arc furnace, an induction furnace, or any other suitable furnace without departing from the spirit or scope of this disclosure.

[0091] Furthermore, system 10 further includes a gating mechanism 16 for pouring molten metal material into a reverse sand casting mold between 1350°C and 1450°C, such that at least one overmolded counterweight is overmolded by the molten metal material, thereby defining the dimensions of the crankshaft 110 to be cast. In one example, the gating mechanism 16 may be a ladle. In this example, the ladle receives molten metal material (e.g., ductile iron alloy) to pour the molten metal material into the reverse sand casting mold. The mold can then be closed or sealed with chemically bonded sand.

[0092] Subsequently, the molten metal material is allowed to be cooled to approximately 450°C in a designated cooling zone (discussed below) to allow the molten metal material (in the multiple molding cavities of the mold) to solidify to form the target part with the dimensions of a crankshaft. Preferably, the crankshaft is made of ductile iron alloy, which comprises: 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), 0 to 0.002 wt% cerium (Ce), and the balance iron (Fe).

[0093] Additionally, system 10 further includes a cooling zone 17 for solidifying molten metal material in the anti-sand casting mold, such that at least one of the crank arms is formed as an overmolded counterweight. The at least one overmolded counterweight is arranged to be metallurgically integrated into at least one of the crank arms.

[0094] In this respect, system 10 further includes a separation unit 18 for separating the target component of the crankshaft from a reverse sand casting mold having multiple molding cavities, thereby defining the crankshaft. In one embodiment, the crankshaft has a weight ratio of a second metal material to a first metal material between 0.20 and 0.50, and preferably 0.36. It should be understood that, if desired, the weight ratio of the second metal material to the first metal material can be before the machining step. In another embodiment, the weight ratio of the second metal material to the first metal material can be after machining without departing from the scope or spirit of this disclosure.

[0095] In one embodiment, the separation unit 18 is arranged to shake off or remove a mold comprising chemically bonded sand from a target part. To achieve removal of the mold from the target part, an automated unit can be used to break the mold and obtain the target part therefrom. For example, a vibrating unit or a workbench with a bottom-collecting screen for receiving mold particles from the mold can be used. It should be understood that any other suitable means can be used to break the mold without departing from the spirit or scope of this disclosure.

[0096] In this embodiment, the separation unit 18 is further arranged to gate the target part after the mold has been removed from the target part. As is known in the art, gatening the target part may involve removing portions of the bonding sand used to fill the mold during casting and closure.

[0097] In one embodiment, the separation unit 18 is further arranged to clean the target component after the gate is opened. In one example, a shot peening machine can be used to apply or spray beads (e.g., metal beads) onto the surface of the target component. To meet alloy design expectations, the separation unit 18 may also include an inspection area in which the mechanical dimensions, mechanical properties, chemical composition, and microstructure of the target component are inspected. In one example, a computerized system such as a coordinate measuring machine (CMM) can be used to measure the mechanical dimensions of the target component, thereby defining the crankshaft 110. Any suitable method and apparatus can be used to evaluate the dimensions, mechanical properties, chemical composition, and microstructure of the crankshaft without departing from the spirit or scope of this disclosure.

[0098] As shown in the figure, system 10 further includes at least one controller 20 that communicates with molding unit 12, furnace 14, casting mechanism 16, and separation unit 18. Controller 20 is configured to control molding unit 12, furnace 14, casting mechanism 16, and separation unit 18. Furthermore, system 10 includes a power source 22 configured to provide power to molding unit 12, furnace 14, casting mechanism 16, separation unit 18, and controller 20.

[0099] According to another embodiment of this disclosure, Figures 3A-3C The illustration shows a crankshaft 210 for an internal combustion engine. As in a previous embodiment, the crankshaft 210 of this embodiment includes at least four main journals 212 (here, five main journals) aligned on a crankshaft rotation axis 214 defining a centerline 216. The crankshaft 210 further includes at least three pin journals 220 (here, four pin journals). Furthermore, each pin journal 220 is disposed and positioned between the main journals 212 about a corresponding pin journal axis 222. Further, each of the corresponding pin journal axes 222 is oriented parallel to and radially spaced from the crankshaft axis 214.

[0100] In this embodiment, each journal 220 is hollow and has a pin hole 224 formed therethrough, adjacent to its corresponding journal axis 222. The pin hole 224 serves to reduce the mass of the journal, thereby reducing the mass of the overmolded counterweight (discussed below). Consequently, the crankshaft 210 has a relatively small total weight, resulting in its mass efficiency.

[0101] Additionally, each of the pin journals 220 is connected to a pair of crank arms 226 for force transmission between the pin journal 220 and the pair of crank arms 226. Furthermore, each pair of crank arms 226 is connected to a corresponding main journal 212 for torque transmission between the pair of crank arms 226 and the main journal 212. Additionally, each of the main journal 212, pin journals 220, and crank arms 226 is made of a first metallic material.

[0102] Furthermore, each crank arm 226 has a metallurgically bonded, molded counterweight 230. Additionally, each counterweight 230 is positioned relative to the centerline 216 and a corresponding pivot journal 220 to achieve balance and stability. Figures 3B-3C As shown, each overmolded counterweight 230 is further attached to its corresponding crank arm 226 by a fastening mechanism 232, such as a bolt. In this embodiment, each bolt is threaded and disposed through a bolt hole 234 formed through the counterweight 230. The threads are arranged to thread through the corresponding crank arm, which has a female threaded hole 236 formed therethrough. Thus, the fastening mechanism 232 provides reinforced fastening of the counterweight to the crank arm.

[0103] As in the previous example discussed above, each counterweight is made of a second metallic material. The second metallic material is denser than the first metallic material to achieve mass efficiency. Furthermore, the crankshaft has a weight ratio of the second metallic material to the first metallic material between 0.20 and 0.50, and preferably 0.36. In one embodiment, the first metallic material comprises a ductile iron alloy and a steel alloy, and the second metallic material comprises a steel alloy and tungsten. In this embodiment, for each counterweight positioned relative to the centerline and opposite the corresponding journal, the crank arm has a weight ratio of counterweight to crank arm between 2.0 and 3.0.

[0104] Each overmolded weight 230 may include one of a full weight 238 and a partial weight 240. In this embodiment, the full weight 238 has more mass than the partial weight 240. For example, the overmolded weight includes a full weight to partial weight weight ratio between 1.5 and 1.7.

[0105] In addition, the cladding-molded counterweight can be composed of a ductile iron alloy having the following composition: 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), 0 to 0.002 wt% cerium (Ce), and the balance iron (Fe). Preferably, the ductile iron alloy has a spheroidization rate of greater than 85%, a Young's modulus in the range of 175 to 195 GPa, and a casting ultimate tensile strength in the range of 750 to 950 MPa.

[0106] like Figure 3AAs shown, the crankshaft 210 may further include an outer coating 242 composed of one of a nickel (Ni) compound and a copper (Cu) compound (or an alloy thereof) to promote metallurgical bonding between the first and second metallic materials. In one embodiment, the outer coating 242 has a thickness of 1 micrometer to 10 micrometers, and preferably 3 micrometers to 5 micrometers. The outer coating 242 may be disposed wholly or partially around the crankshaft 210 without departing from the spirit or scope of this disclosure.

[0107] Figure 4 A method 310 for manufacturing a crankshaft with an alternative material is illustrated according to an example of this disclosure. In this example, method 310 can be achieved by... Figure 1 The system implementation. As shown in the figure, method 310 includes a reverse sand casting mold for providing the crankshaft in block 312. As discussed above and as... Figures 2A-2B As shown, the crankshaft includes at least four main journals aligned on the crankshaft rotation axis that defines a centerline. The crankshaft further includes at least three pivot journals.

[0108] As described above, each journal pin is disposed and positioned between the main journals around its respective journal pin axis. Furthermore, each of the respective journal pin axes is oriented parallel to and radially spaced from the crankshaft axis. Additionally, each journal pin is coupled to a pair of crank arms for force transmission between the journal pin and the pair of crank arms. Further, each pair of crank arms is coupled to a corresponding main journal for torque transmission between the pair of crank arms and the main journal. Moreover, each of the main journals, journal pins, and crank arms is arranged to be made of a first metallic material.

[0109] like Figures 2A-2B In this design, at least one of the crank arms is arranged to have a molded counterweight. Furthermore, the molded counterweight is arranged to be molded by and metallurgically bonded to at least one of the crank arms. Each molded counterweight is arranged to be positioned relative to a centerline and a corresponding journal to achieve balance and stability. Further, each molded counterweight is made of a second metal material. The second metal material is arranged to be denser than the first metal material to achieve mass efficiency.

[0110] In this example, method 310 further includes, in block 314, placing at least one overmolded counterweight in the crankshaft's anti-mold. The overmolded counterweight may be formed by machining, casting, billet forming, forging, or any other suitable means without departing from the spirit or scope of this disclosure.

[0111] In this example, method 310 further includes melting a first metallic material in block 316 to define a molten metallic material. In one example, the first metallic material can be melted using the furnace described above. The furnace can be an electric arc furnace, an induction furnace, or any other suitable furnace without departing from the spirit or scope of this disclosure.

[0112] Method 310 further includes, in block 318, pouring molten metal material into an inverted sand casting mold such that at least one overmolded counterweight is overmolded by the molten metal material. In one example, the pouring step can be implemented Figure 1 The system includes a gating mechanism and a ladle. In this example, the ladle receives molten metal material and then pours the molten metal material into a mold. The mold can then be closed or sealed with chemically bonded sand.

[0113] In this respect, method 310 further includes, in frame 320, solidifying molten metal material in a reverse sand casting mold such that at least one of the crank arms is formed as an overmolded counterweight. The at least one overmolded counterweight is metallurgically bonded to at least one of the crank arms defining the crankshaft.

[0114] The solidification step may involve allowing the molten metal material to cool to approximately 450°C. Cooling can be carried out in a designated cooling zone or within a mold to solidify the molten metal material (within multiple molded cavities of the mold) to form the target crankshaft casting.

[0115] Method 310 further includes, in block 322, separating the crankshaft from the anti-sand casting mold. The crankshaft has a weight ratio of a second metal material to a first metal material between 0.20 and 0.50. In one example, the separation step includes shaking off or removing the mold containing chemically bonded sand from the cast crankshaft. Figure 1 In System 10, to remove the mold from the cast crankshaft, an automated unit is used to destroy the mold and obtain the cast crankshaft therefrom. For example, a vibrating unit or a worktable with a bottom collecting screen for receiving mold particles from the mold can be used. It should be understood that mold destruction can be achieved by any suitable means, such as a vibrating unit, without departing from the spirit or scope of this disclosure.

[0116] In this example, the separation step may include gate-gating the target crankshaft casting after removing the mold from the crankshaft, and cleaning the target crankshaft casting after gate-gating. Figure 1In system 10, a shot peening machine can be used to apply or spray metal beads onto the surface of the target crankshaft casting. To meet design expectations, the separation unit may also include an inspection area where the dimensions, mechanical properties, chemical composition, and microstructure of the target crankshaft casting are inspected. For example, a computerized system such as a CMM can be used to measure the mechanical dimensions of the target crankshaft, thereby defining the crankshaft of this disclosure. Any suitable method and apparatus can be implemented to evaluate the mechanical dimensions, mechanical properties, chemical composition, and microstructure of the crankshaft without departing from the spirit or scope of this disclosure.

[0117] In one example, the first metallic material comprises a ductile iron alloy and a steel alloy, and the second metallic material comprises a steel alloy and tungsten. Preferably, the weight ratio of the second metallic material to the first metallic material is 0.36.

[0118] In another example, the ductile iron alloy comprises 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), and 0 to 0.002 wt% cerium (Ce).

[0119] The description in this disclosure is exemplary in nature only, and variations thereof that do not depart from the spirit and scope of this disclosure are intended to fall within its scope. Such variations should not be considered as departing from the spirit and scope of this disclosure.

Claims

1. A system for manufacturing a crankshaft having an alternative material, the system comprising: A molding unit arranged to form a reverse sand casting mold for a crankshaft, the mold comprising at least one molding cavity having a pattern having dimensions of a crankshaft, the crankshaft comprising: At least four main journals aligned on the crankshaft rotation axis defining the center line; and At least three journals are provided, each journal being disposed around a corresponding journal axis and positioned between main journals. Each of the corresponding journal axes is oriented parallel to and radially spaced from the crankshaft axis. Each journal is connected to a pair of crank arms for force transmission between the journal and the pair of crank arms. Each pair of crank arms is connected to a corresponding main journal for torque transmission between the pair of crank arms and the main journal. Each of the main journals, journals, and crank arms is arranged to be made of a first metallic material. At least one of the crank arms is arranged to have a molded counterweight, the molded counterweight being arranged to be molded and metallurgically bonded to the at least one of the crank arms, each molded counterweight being arranged to be positioned relative to the centerline and opposite to the corresponding journal pin for balance and stability, each molded counterweight being made of a second metal material, the second metal material being arranged to be denser than the first metal material for mass efficiency. The molded counterweight is placed in at least one molded cavity; A furnace for melting a first metallic material between 1400 degrees Celsius (°C) and 1600 degrees Celsius to define the molten metallic material; A gating mechanism for pouring molten metal material into a reverse sand casting mold between 1350°C and 1450°C, such that at least one overmolded counterweight is overmolded by the molten metal material. A cooling zone for solidifying molten metal material in a reverse sand casting mold, such that at least one of the crank arms is formed as an overmolded counterweight, the at least one overmolded counterweight being metallurgically bonded to at least one of the crank arms defining the crankshaft at about 450°C. A separation unit for separating the crankshaft from the reverse sand casting mold, wherein the crankshaft has a weight ratio of a second metal material to a first metal material between 0.20 and 0.50; A controller that communicates with the molding unit, furnace, casting mechanism, and slitting unit, the controller being configured to control the molding unit, furnace, casting mechanism, and slitting unit; and A power source configured to provide power to the molding unit, furnace, casting mechanism, separation unit, and controller.

2. The system according to claim 1, wherein, The first metallic material includes ductile iron alloy and steel alloy, and the second metallic material includes steel alloy and tungsten.

3. The system according to claim 1, wherein, For each counterweight positioned relative to the centerline and the corresponding journal, the crank arm has a counterweight to crank arm weight ratio of 2.

5.

4. The system according to claim 1, wherein, Overmolded weights include either full weights or partial weights, with the full weights having more mass than the partial weights, and the overmolded weights having a weight ratio of 1.6 between the full weights and the partial weights.

5. The system according to claim 1, wherein, The ductile iron alloy comprises 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), and 0 to 0.002 wt% cerium (Ce).

6. The system according to claim 2, wherein, Ductile iron alloys have a spheroidization rate of more than 85%, a Young's modulus in the range of 175 to 195 GPa, and a casting ultimate tensile strength in the range of 750 to 950 MPa.

7. A method for manufacturing a crankshaft having a substitute material, the method comprising: A reverse sand casting mold is provided for a crankshaft, the crankshaft comprising: At least four main journals aligned on the crankshaft rotation axis defining the center line; and At least three journals are provided, each journal being disposed around a corresponding journal axis and positioned between main journals. Each of the corresponding journal axes is oriented parallel to and radially spaced from the crankshaft axis. Each journal is connected to a pair of crank arms for force transmission between the journal and the pair of crank arms. Each pair of crank arms is connected to a corresponding main journal for torque transmission between the pair of crank arms and the main journal. Each of the main journals, journals, and crank arms is arranged to be made of a first metallic material. At least one of the crank arms is arranged to have a molded counterweight, the molded counterweight being arranged to be molded by and metallurgically bonded to the at least one of the crank arms, each molded counterweight being arranged to be positioned relative to the centerline and opposite to the corresponding journal to achieve balance and stability, each molded counterweight being arranged to be made of a second metal material, the second metal material being arranged to be denser than the first metal material to achieve mass efficiency; At least one overmolded counterweight is placed in the crankshaft's reverse mold; The first metallic material is melted between 1400 degrees Celsius (°C) and 1600 degrees Celsius to define the molten metallic material; Molten metal material is poured into a reverse sand casting mold between 1350°C and 1450°C, such that at least one overmolded counterweight is overmolded by the molten metal material. The molten metal material in the reverse sand casting mold is solidified, such that at least one of the crank arms is formed as an overmolded counterweight, the at least one overmolded counterweight being metallurgically bonded to at least one of the crank arms defining the crankshaft; and The crankshaft is separated from the reverse sand casting mold, and the crankshaft has a weight ratio of second metal material to first metal material between 0.20 and 0.

50.

8. The method according to claim 7, wherein, The first metallic material includes ductile iron alloy and steel alloy, and the second metallic material includes steel alloy and tungsten.

9. The method according to claim 7, wherein, The weight ratio of the second metallic material to the first metallic material is 0.

36.

10. The method according to claim 8, wherein, The ductile iron alloy comprises 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), and 0 to 0.002 wt% cerium (Ce).

11. A crankshaft manufactured using the system of any one of claims 1 to 6 or the method of any one of claims 7 to 10, the crankshaft comprising: At least four main journals aligned on the crankshaft rotation axis that defines the center line; as well as At least three journals are provided, each journal being disposed around a corresponding journal axis and positioned between main journals. Each of the corresponding journal axes is oriented parallel to and radially spaced from the crankshaft axis. Each journal is connected to a pair of crank arms for force transmission between the journal and the pair of crank arms. Each pair of crank arms is connected to a corresponding main journal for torque transmission between the pair of crank arms and the main journal. Each of the main journals, journals, and crank arms is made of a first metallic material. Each crank arm has a metallurgically bonded, molded counterweight, each counterweight being positioned relative to the centerline and the corresponding journal pin to achieve balance and stability, each counterweight being made of a second metal material that is denser than the first metal material to achieve mass efficiency, and the crankshaft having a weight ratio of the second metal material to the first metal material between 0.20 and 0.

50.

12. The crankshaft according to claim 11, wherein, The first metallic material includes ductile iron alloy and steel alloy, and the second metallic material includes steel alloy and tungsten.

13. The crankshaft according to claim 11, wherein, The weight ratio of the second metallic material to the first metallic material is 0.

36.

14. The crankshaft according to claim 11, wherein, For each counterweight positioned relative to the centerline and the corresponding journal, the crank arm has a counterweight-to-crank arm weight ratio between 2.0 and 3.

0.

15. The crankshaft according to claim 11, wherein, Each encapsulated molded weight includes either a full weight or a partial weight, with the full weight having more mass than the partial weight.

16. The crankshaft according to claim 15, wherein, Overmolded counterweights include a full counterweight to partial counterweight weight ratio between 1.5 and 1.

7.

17. The crankshaft according to claim 11, wherein, The ductile iron alloy comprises 2.2 to 3.2 wt% carbon (C), 1.7 to 2.3 wt% silicon (Si), 0.2 to 0.6 wt% manganese (Mn), 0 to 0.03 wt% phosphorus (P), 0 to 0.02 wt% sulfur (S), 0.2 to 0.6 wt% copper (Cu), 0.1 to 0.4 wt% chromium (Cr), 0.4 to 0.8 wt% nickel (Ni), 0.15 to 0.45 wt% molybdenum (Mo), 0.2 to 1.0 wt% cobalt (Co), 0.02 to 0.06 wt% magnesium (Mg), and 0 to 0.002 wt% cerium (Ce).

18. The crankshaft according to claim 12, wherein, Ductile iron alloys have a spheroidization rate of more than 85%, a Young's modulus in the range of 175 to 195 GPa, and a casting ultimate tensile strength in the range of 750 to 950 MPa.

19. The crankshaft of claim 12, further comprising an outer coating composed of a nickel (Ni) and a copper (Cu) compound to promote metallurgical bonding between the first metallic material and the second metallic material.

20. The crankshaft according to claim 19, wherein, The outer coating has a thickness of 1 micrometer to 10 micrometers.

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