CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This PCT Patent Application claims the benefit of U.S. Provisional Patent

Application Serial Number 62/296,231 filed on February 17, 2016 entitled "Die Casting Die With Removable Inserts," the entire disclosure of the application being considered part of the disclosure of this application and hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0002] The invention relates generally to a die casting apparatus for manufacturing metal parts, such as parts for automotive applications, a method for manufacturing the die casting apparatus, and a method for manufacturing metal parts using the die casting apparatus.

2. Related Art

[0003] Die casting is oftentimes used to form metal parts having various shapes, for example parts used in automotive vehicle applications, such as pillars, headers, rails, twist axles, spring links, control arms, bumpers, beams, side panels, or any other type of strength driven chassis component, body in white component, or safety-related component. The die casting process includes forcing molten metal into a mold cavity under high pressure. The mold cavity is located between an upper die and a lower die which are typically formed of hardened tool steel. Each die presents a forming surface having a shape depending on the geometry of the part to be formed.

[0004] Over time, the forming surfaces of the dies can experience significant erosion and wear due to the high temperatures and harsh conditions of the casting process. Certain areas of the forming surfaces are more prone to wear, depending on the process conditions and geometry of the part being formed. Typically, both dies must be replaced after about 60,000 to 70,000 casting cycles due to wear and erosion along the forming surfaces, which increases production time and costs.

SUMMARY

[0005] The invention provides a die casting apparatus for manufacturing metal parts, such as parts used in automotive vehicle applications. The die casting apparatus includes an upper die and a lower die providing a mold cavity therebetween, and each of the dies presents a forming surface. At least one of the dies includes at least one insert and at least one sub-insert each presenting a portion of the forming surface. The at least one insert and the at least one sub-insert are removable from the dies and replaceable. The at least one insert and sub-insert are typically disposed in locations prone to wear. Since the inserts and sub-inserts can be removed and replaced after significant wear, it is no longer necessary to replace the entire die during high volume production. Thus, the least one insert and sub- insert improve service life of the die casting apparatus and reduce production time and costs.

[0006] Another aspect of the invention is a method of manufacturing a die casting apparatus for manufacturing metal parts. The method includes providing an upper die and a lower die with a mold cavity therebetween, wherein each of the dies present a forming surface. The method further includes disposing at least one insert and at least one sub-insert in at least one of the dies, wherein the at least one insert and the at least one sub-insert present a portion of the forming surface. The method also includes removing the at least one insert and/or the at least one sub-insert from the dies after about 60,000 casting cycles; and replacing the at least one insert and/or the at least one sub-insert after removing from the dies. [0007] Yet another aspect of the invention provides a method of manufacturing metal parts. The method includes casting a plurality of metal parts in a die casting apparatus, wherein the die casting apparatus includes an upper die and a lower die providing a mold cavity therebetween, each of the dies present a forming surface, and at least one of the dies includes at least one insert and at least one sub-insert each presenting a portion of the forming surface. The method also includes removing the at least one insert and/or the at least one sub-insert from the dies after about 60,000 casting cycles; and replacing the at least one insert and/or the at least one sub-insert after removing the at least one insert and/or the at least one sub-insert from the dies.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Other advantages of the present invention 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:

[0009] Figure 1 is a side cross-section view of a die casting apparatus according to an example embodiment;

[0010] Figure 2 illustrates a rear rail casting die including a replaceable insert and two sub-inserts according to an example embodiment;

[0011] Figure 3 illustrates a perspective view of the rear rail casting die of Figure 2 and including a cross-section of the replaceable insert and sub-inserts;

[0012] Figure 4 is a side view of the first sub-insert of Figure 2 showing cooling lines formed therein;

[0013] Figure 5 is a perspective view of the insert and the first sub-insert of Figure

2; and

[0014] Figure 6 is a perspective view of the rear rail casting die of Figure 2 showing cooling lines formed in the insert. DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0015] The invention provides a die casting apparatus 10 for manufacturing metal parts having various shapes, such as parts used in automotive vehicle applications.

Examples of parts that can be formed using the die casting apparatus 10 include pillars, headers, rails, twist axles, spring links, control arms, bumpers, beams, side panels, strength driven chassis components, body in white components, and safety-related components. The die casting apparatus 10 includes an upper die 12 and a lower die 14 each having a forming surface 16, 18 to provide a mold cavity 20 therebetween. The forming surfaces 16, 18 can have various different shapes, depending on the part to be formed. Figures 2, 3, 5, and 6 illustrate the lower casting die 14 according to an example embodiment which is designed to form a rear rail of an automotive vehicle.

[0016] At least one of the casting dies 12, 14 of the die casting apparatus 10 includes at least one replaceable insert 22. The insert 22 provides at least a portion of the forming surface 18 which shapes the molten metal into the geometry of the part to be formed. The replaceable insert 22 is typically located in an area prone to wear and/or erosion during the casting process. Thus, the shape and size of the insert 22 typically vary in each case. The replaceable insert 22 has a surface area along the forming surface 18 and also a thickness extending from the forming surface 18 into the die 12, 14. In the example embodiment shown in the Figures, the lower die 14 includes one insert 22 providing a significant portion of the forming surface 18. The insert 22 can be formed of the same material used to form the casting die 14, for example steel, or a different material, such as another metal.

[0017] At least one of the casting dies 12, 14 of the die casting apparatus 10 can also include at least one sub-insert 24, 26. Each sub-insert 24, 26 is located along the insert 22 or along another sub-insert 24, 26. The sub-inserts 24, 26 also provide a portion of the forming surface 16, 18. The sub-inserts 24, 26 are typically located in areas even more prone to wear and/or erosion during the casting process than the inserts 22. Thus, the shape and size of the sub-inserts 24, 26 typically vary in each case. The sub-inserts 24, 26 have a surface area along the forming surface 18 and also a thickness extending from the forming surface 18 into the die 12, 14. In the example embodiment shown in the Figures, two sub- inserts 24, 26, are located along the insert 22 and are surrounded by the insert 22. The first sub-insert 24 extends longitudinally though a center portion of the insert 22 to an edge of the insert 22. The surface area of the first sub-insert 24 is less than the surface area of the insert 22. The second sub-insert 26 is disposed along a small region of the first sub-insert 24, and the surface area of the second sub-insert 26 has a triangular shape. The surface area of the second sub-insert 26 is less than the surface area of the first sub-insert 24. In the example embodiment, the total surface area provided by the sub-inserts 24, 26 is less than the surface area provided by the one insert 22. The total surface area of all of the sub- inserts 24, 26 is typically less than the total surface area of all of the inserts 22 in the dies 12, 14. The sub-inserts 24, 26 can be formed of the same material used to form the casting die 14 and/or the inserts 22 for example steel, or a different material, such as another metal.

[0018] As mentioned above, the forming surfaces 16, 18 of the casting dies 12, 14 are typically subject to significant wear and/or erosion during high volume production. Comparative casting dies are typically replaced after about 60,000 to 70,000 casting cycles due to such wear and erosion. However, in the present case, only inserts 22 and sub-inserts 24, 26 located in the areas most prone to wear need to be replaced. The inserts 22 and sub- inserts 24, 26 can be easily removed and replaced without having to replace the entire die 14. This leads to reduced cycle time, reduced production costs, and increased quality of the parts formed, particularly during high volume production. [0019] Optionally, a wear and/or heat resistant coating can be applied to the inserts

22 and/or sub-inserts 24, 26 to further increase service life to 150,000 casting cycles or more. The inserts 22 and sub-inserts 24, 26 allow access to tight areas in the die casting apparatus 10 for the coating process and also a weld process. The coating can be formed of various different compositions and by various difference processes. For example, the coating can be applied by nitriding or nitrocarburizing. According to one example embodiment, a nitride coating or a coating applied by a surface treatment sold under the trade name DY A-BLUE ^® is applied to the inserts 22 and/or sub-inserts 24, 26. The surface treatment sold under the trade name DYNA-BLUE ^® is a low temperature ferritic nitrocarburizing surface treatment typically at 950°-1060°F. The DYNA-BLUE ^® surface treatment yields two, distinct metallurgical characteristics, including a compound layer of 1880 Vickers (75+ Rockwell C) .0005"-.002", and a nitrogen enriched diffusion zone which is .002 - .010 inch deep to support the compound zone.

[0020] To enhance cooling of the die 12, 14 in critical areas, at least one of the inserts 22 and/or at least one of the sub-inserts 24, 26 can have a self-contained cooling system, such as cooling channels 28, 30 extending therethrough. The cooling channels 28, 30 could have various different shapes and be located in various different locations, depending on the locations of the die 12, 14 prone to heat. In the example embodiments, the insert 22 and the first sub-insert 24 include a plurality of the cooling channels 28, 30 having a cylindrical shape and extending traverse or perpendicular to the forming surfaces 16, 18 for conveying water or another cooling fluid therethrough. Figure 4 illustrates the cooling channels 28 formed in the first sub-insert 24, and Figure 6 illustrates the cooling channels 30 formed in the insert 22 according to the example embodiment. The cooling channels 28, 30 reduce the temperature of the casting die 12, 14 during production, which improves cycle time and thus quality of the parts formed. [0021] Another aspect of the invention provides a method of manufacturing the die casting apparatus 10 described above. The method includes providing the upper die 12 and the lower die 14 which form the mold cavity 20 therebetween. At least one of the dies 12, 14 includes at least one insert 22 and/or at least one sub-insert 24, 26. The inserts 22 and sub-inserts 24, 26 form portions of the forming surfaces 16, 18 of the dies 12, 14. The method can also include providing the cooling channels 28, 30 in the inserts 22 and/or sub- inserts 24, 26. The method can optionally include applying the wear and/or heat resistant coating to the inserts 22 and/or sub-inserts 24, 26.

[0022] Yet another aspect of the invention provides a method of manufacturing the metal parts, for examples parts used in automotive vehicle applications, using the die casting apparatus 10 described above. The method includes closing the upper die 12 and the lower die 14 to provide the mold cavity 20 therebetween, forcing molten metal into the mold cavity 20 under high pressure, and allowing the molten metal to solidify in the mold cavity 30 to form the metal part. Once the molten metal solidifies, the method includes opening the dies 12, 14 and removing the metal part. These steps can be repeated thousands of times for high volume production. When the inserts 22 or sub-inserts 24, 26 become worn or eroded due to the high temperatures and harsh conditions of the casting process, for example after about 60,000 casting cycles, the inserts 22 and/or sub-inserts 24, 26 can be removed and replaced with new or different inserts 22 and/or sub-inserts 24, 26 to improve the quality of the forming surface 16, 18 used to shape the molten metal. It is no longer necessary to replace the entire die 12, 14, as in prior processes. Thus, the production time and costs is significantly reduced. After replacing the inserts 22 and/or sub-inserts 24, 26, the die casting apparatus 10 can continue casting the metal parts. [0023] Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described with within the scope of the invention.