Chill assembly

A chill assembly for chilling a molten material during formation of a part is disclosed. The chill assembly includes an upper platform and a mold platform for receiving a mold package to be filled with the molten material to form the part. The upper platform has a first platen moveable in a vertical direction relative to the molding platform. A plurality of chills are moveably supported by the first platen for quenching the molten material. Each of the chills are moveable between a pre-chill position and a post-chill position. An alignment sub-assembly engages the chills and aligns the chills in the pre-chill position. The alignment sub-assembly re-aligns the chills after the chills have quenched the molten material and moved to the post-chill position. The alignment sub-assembly is capable of precisely aligning and re-aligning the chills after each successive quenching of the molten material.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention provides a chill assembly for chilling a molten material during formation of a part.

2. Description of the Related Art

Various related art assemblies disclose a chill for chilling, or quenching, a part during formation. These assemblies include a first platen driven by a lift to raise and lower the first platen. A mold package is positioned underneath the first platen and a liquid metal or other molten material is introduced into the package to form the part. The material is injected into the package and takes the form of the part. A chill extending from the first platen is brought into contact with the mold package and the liquid metal or molten material

Related art assemblies generally disclose the chill as a rod extending the length of the first platen or the length of the mold package. The chill contacts the molten material in the mold package and begins to quench the molten material to form the part. The quenching of the part improves the properties of the part in the areas surrounding the chill.

However, when the molten material is chilled, the part shrinks inward from the ends toward a center of the part. These various assemblies do not allow for movement of the chills with the shrinkage of the part during cooling. Since the rod is fixed to the first platen, the chill becomes wet with the liquid metal. By wet it is meant that the chill becomes fixed to the part and must be removed from the first platen and travels with the part until it can be removed. This causes the process of forming the part to be very slow since the chill cannot be collected until after the part has finished processing. Alternately, these related art assemblies require that multiple chills be available to reattach to the first platen for the next successive part, while the previous chill is fixed in the part and prior to reclaiming it.

Therefore, it would be advantageous to provide an assembly that allowed for quenching of a molten material with a chill that was recoverable prior to completion of the part. Further, it would be advantageous to provide the assembly with a plurality of chills that are moveable to compensate for the shrinkage of the part during quenching and having a re-alignment mechanism to reposition the chills in a pre-chill position after quenching.

BRIEF SUMMARY OF THE INVENTION AND ADVANTAGES

The subject invention provides a chill assembly for chilling a molten material during formation of a part. The assembly includes a mold platform for receiving a mold to be filled with a molten material to form a part and a first platen moveable in a vertical direction relative to the molding platform. A plurality of chills are moveably supported by the first platen for quenching the molten material. Each of the chills are moveable between a pre-chill position prior to quenching and a post-chill position after quenching. An alignment sub-assembly engages the chills and aligns the chills in the pre-chill position after the chills have quenched the molten material and the chills have moved to the post-chill position.

The subject invention further provides a method of forming the part from molten material. The method comprises the steps of disposing the mold for the part on the mold platform adjacent the first platen. The plurality of chills are supported by the second platen and positioned in a pre-chill position relative to the mold. The molten material is injected into the mold and the first platen is moved into contact with the mold such that the chills quench the molten material as the molten material begins to cool to form the part. The plurality of chills moved along the X-direction simultaneously with a shrinkage occurring in the part as the molten material cools such that the chills end in a post-chill position. The first platen is then moved out of contact with the mold to remove the chills from the molten material and the plurality of chills are re-aligned from the post-chill position to the pre-chill position.

The subject invention overcomes the inadequacies that characterize the related art assemblies. Specifically, the subject invention provides an assembly that has a plurality of chills that are moveable between a pre-chill position and a post-chill position to compensate for shrinkage of the part during formation. Further, the subject invention provides an alignment sub-assembly for re-aligning the chills in the pre-chill position in preparation for molding the next part. One improved characteristic of the part formed according to the subject invention is increased strength in the desired area where the chill remains in contact with the part while shrinking.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the figures, wherein like numerals indicate like or corresponding parts throughout the several views, a chill assembly for chilling a molten material during formation of a part15is shown generally at10inFIG. 1. The chill assembly10includes an upper platform12and a mold platform14for receiving a mold package16to be filled with the molten material to form the part15. The mold package16is preferably a sand package; however, other packages may be used as is known by those skilled in the art. The mold package16has a material inlet (not shown) for receiving a molten, or fluidized, material, such as a liquid metal, which forms the part15. It is to be appreciated that other types of material may be used with the subject invention, however, in one embodiment the material is molten aluminum. Typical parts15formed from the mold package16include engine blocks, cylinder heads, and any other parts15that require reinforced areas having improved strength.

The upper platform12has a first platen18moveable in a vertical direction relative to the molding platform. A lift20is in engagement with the first platen18for driving the first platen18upward and downward in the vertical direction. Preferably, the lift20is a hydraulic lift. However, it is to be appreciated, that other lifts are capable of use with the subject invention. The lift20may be supported on or adjacent the upper platform12.

Referring toFIG. 2, a plurality of chills22are moveably supported by the first platen18for quenching the molten material. Each of the chills22is moveable between a pre-chill position24and a post-chill position26. The pre-chill position24is the position of the chills22prior to quenching the molten material as illustrated inFIGS. 2,3, and6. The post-chill position26is the position of the chills22after the part15has been quenched as illustrated inFIGS. 4 and 5. Each of the chills22is moveable along a X-direction28between the pre-chill22and the post-chill positions26. When the chills22contact the molten material and begin to quench the molten material, the part15shrinks inward from each of the ends toward the center of the part15. When the molten material is aluminum, the part15shrinks at a rate of about one-eighth of an inch per foot (⅛ inch per foot). Therefore, the rate of shrinkage at the center of the part15is less than the rate of shrinkage at the ends of the part15. The inward shrinking of the molten material is defined as along the X-direction28and the chills22are able to move at the same rate that the part15is shrinking. Since the rate of shrinkage is different throughout the part15, each of the chills22may move more or less depending upon the respective position in the part15. For example, the chills22nearer the center of the part15will move very little, whereas the chills22nearer the ends of the part15will move more.

The chill22has a quenching surface30for engaging the molten material. The quenching surface30, i.e., the surface that contacts the part15being cooled, includes the outer edge and surface, the inner walls, and the inner top surface of the chills22. As should be appreciated, the quenching surface30of the present invention is inserted into the part15being cooled to cool a greater area than traditional techniques. The surface may be generally U-shaped as illustrated in the Figures. The portion of the part15being cooled, when contacted by this surface, has an increased strength compared to the rest of the part15. Since the chills22can move in the X-direction28, the chills22remain in contact with the surface longer so that the part15has increased strength over a larger area. The larger area, for the embodiment shown with a U-shaped quenching surface30, radiates outward from the quenching surface30into the part15.

To improve the quenching of the chills22, each of the plurality of chills22has a cooling fluid inlet32and a cooling fluid outlet34for circulating a fluid (not shown) through the chill22. The chill22can be any shape depending upon the type of part15to be formed. The cooling fluid lowers the temperature of the chills22and quenches the molten material. The cooling fluid may be any fluid capable of cooling the chills22and absorbing heat from the molten materials, such as, but not limited to, water.

An alignment sub-assembly36engages the chills22and aligns the chills22in the pre-chill position24. The alignment sub-assembly36re-aligns the chills22after the chills22have quenched the molten material and have moved to the post-chill position26. The alignment sub-assembly36must be capable of precisely aligning and re-aligning the chills22after each successive quenching of the molten material. Further, the alignment sub-assembly36must repeatedly position the chills22in the same pre-chill position24to ensure that the parts15are uniform and acceptable. In order to repeat the alignment and re-alignment, the alignment sub-assembly36includes a locator bar38supported by the first platen18. The locator bar38defines a plurality of detents40corresponding to the pre-chill position24. A pair of end caps42is disposed between the locator bar38and the first platen18to support the locator bar38. A plurality of locators44are supported by the chills22such that the locators44engage the detents40to re-align the chills22in the pre-chill position24.

In order to engage the locators44and the detents40, the alignment sub-assembly36further comprises a second platen46moveable in the vertical direction independent of the first platen18. The second platen46may be driven in the vertical direction by any known methods such as a motor or the lift20. The second platen46supports the chills22and brings the locators44into engagement with the detents40for re-aligning the chills22. The chills22are mounted to the second platen46by brackets48. The chills22are slideably supported on a chill rod50that interconnects the chills22to the brackets48. The chill rod50is at a lower end52of the brackets48. The chills22are slideably supported on the chill rod50such that the chills22are capable of sliding in the X-direction28. The X-direction28is preferably defined from the end of the part15towards a center of the part15when the part15is cooled such that the chills22on the outer ends of the chill rod50slide toward the chills22in the middle of the chill rod50.

A bracket rod54is mounted to the second platen46and supports the brackets48at an upper end56. Spacer posts58are mounted between the inner most brackets48maintain a distance therebetween. The brackets48move in unison with the second platen46to move the chills22vertical relative to the locator bar38. The brackets48have slots60between the upper end56and the lower end52to allow for vertical movement about the locator bar38, such that the locator bar38rides within the slots60and remains stationary relative to the brackets48. The alignment sub-assembly36also includes a spring assembly62between the locator bar38and the first platen18. The spring assembly62biases the locator bar38in a downward direction. The spring assembly62allows the locator bar38to flex when contacted by the locators44. The flexing of the locator bar38reduces wear of both the locator bar38and the locators44. In the preferred embodiment, the spring assembly62is mounted to at least one of the end caps42.

The plurality of chills22are moved vertically by the vertical movement of the second platen46and the brackets48. The locators44contact the locator bar38and re-align the chills22to the pre-chill position24, while forcing the locator bar38against the downward force. This moves the individual chills22back to the pre-chill or original starting position after the shrinking of the part15moved them towards the center of the part15to the post-chill position26.

The locator bar38flexes to prevent any damage to the detents40and the locators44. Since the locator bar38is spring loaded, when the locators44engage the detents40, the locator bar38is able to flex with vertical movement of the chills22. This prevents the locator bar38from becoming damaged or from damaging the chills22. If the locator bar38or chills22where damaged, or misaligned, then the part15to be formed may not meet the desired tolerances or specifications as a result of the chills22not being precisely aligned in the pre-chill position24.

The subject invention further includes a mold package locator64mounted to the mold platform14for locating the mold relative to the first platen18. The mold package16is positioned on the mold platform14using the mold package locator64to ensure that the mold package16will receive the chills22in the pre-chill position24for each one of the parts15to be formed. The mold package16may have wheels66for moving the mold package16onto the mold platform14prior to positioning with the mold package locator64. However, the mold package16may be delivered to the mold platform14by other methods known to those skilled in the art.

The subject invention provides a method of forming the part15from molten material. Referring toFIG. 3, the method includes the steps of disposing the mold for the part15on the mold platform14adjacent the first platen18. The plurality of chills22are supported by the second platen46and positioned in the pre-chill position24relative to the mold. When in the pre-chill position24, the chills22are spaced from one another by a predetermined spacing. The first platen18is then moved into contact with the mold such that the chills22are positioned to quench the molten material as the molten material begins to cool to form the part15. The molten material is injected into the mold and the material begins to flow into the mold package16and contacts the chills. The part15forms about the chills22as illustrated.

With reference toFIG. 4, the quenching action of the chills22causes the material forming the part15to shrink inwards from the ends towards the center of the part15. This shrinkage moves the chills22from the pre-chill position24towards the center of the mold package16from each end. As illustrated, the chill22in the center of the part15moves little if at all. The chills22that are next adjacent the center moved toward the chill22in the center. The chills22farthest from the center moves the most toward the center. The predetermined spaced is reduced in the post-chill position26.

Because the chills22can move with the shrinkage of the part15, the area that is cooled on the part15radiates to a larger area and has increased strength characteristics. Those skilled in the art may recognize that since the chills22are able to move with the shrinkage of the part15, the chills22remain in contact for a longer period of time. Without intending to be bound, it is believed that it is the longer period of time that increases the cooling and increases the strength. Also, because the chill22can move with the shrinkage of the part15, the chills22are less likely to become wet with the material and can therefore be removed when the quenching is complete and before the part15has finished processing. As the chills22remain in contact with the molten material, the cooling fluid is being pumped through the chills22to increase the quenching.

As shown inFIG. 5, once quenching is complete, the chills22end in the post-chill position26set inwards from the ends of the part15and the first platen18is moved out of contact with the mold to remove the chills22from the molten material. It is to be appreciated that the chills22may be removed from the part15as soon as the part15attains a semi-solid state. The semi-solid state may be have a solid skin formed about the part such that interior portions of the part may remain in the molten state. The part15does not have to be completely formed prior to removing the chills22. Moreover, after the chills22are removed, the semi-solid part may be subject to a spraying with a fluid to further quench the part15. The fluid may be water, air, or any other fluid capable of dissipating heat from the semi-solid part15. The spraying rapidly forms the part15and further improves the physical characteristics of the part15.

Next, the chills22are re-aligned from the post-chill position26to the pre-chill position24. The re-alignment is done automatically upon removing the chills22from the mold. Therefore, little or no user intervention is required and the chills22are precisely aligned for each successive part15to be formed. InFIG. 6, the second platen46is moved independent of the first platen18in the upward direction causing the locators44to move toward the detents40of the locator bar38. The locators44are shown being received in the detents40inFIG. 6. The locator bar38engages the locators44mounted to the chills22which slides the chills22outward to the pre-chill position24, which is the position the chills22were in before the shrinkage of the part15moved them inwards to the post-chill position26. The chills22are then re-aligned from the post-chill position26to the pre-chill position24. When the locators44engage the locating bar, the locator bar38flexes to overcome the biasing force of the spring assembly62to prevent wear and damage.