COVER DIE HOLDER BLOCK FOR HIGH-PRESSURE DIE CASTING APPARATUS

Abstract

A cover die holder block for a high-pressure die casting apparatus includes: a first cover die holder block component having defined therein at least a portion of a cover die holder block pocket surface configured to accommodate at least one die insert defining a mold surface, and at least portions of two opposing lock faces adjacent the cover die holder block pocket surface; and a second cover die holder block component, the second cover die holder block component having two projections extending therefrom, each projection being accommodated in a corresponding recess defined in the first cover die holder block component behind a respective lock face, in a direction of largest stress applied to the lock face during operation. The first and second cover die holder block components are separately fabricated and are connected to yield the cover die holder block.

Claims

1. A cover die holder block for a high-pressure die casting apparatus, the cover die holder block comprising: a first cover die holder block component having defined therein at least a portion of a cover die holder block pocket surface configured to accommodate at least one die insert defining a mold surface, and at least portions of two opposing lock faces adjacent the cover die holder block pocket surface; and a second cover die holder block component, the second cover die holder block component having two projections extending therefrom, each projection being accommodated in a corresponding recess defined in the first cover die holder block component behind a respective lock face, in a direction of largest stress applied to the lock face during operation, the first and second cover die holder block components being separately fabricated and being connected to yield the cover die holder block.

2. The cover die holder block of claim 1, wherein each of the first cover die holder block component and the second cover die holder block component is fabricated from a respective, single piece of material.

3. The cover die holder block of claim 1, wherein the first cover die holder block component and the second cover die holder block component are connected by bolts.

4. The cover die holder block of claim 3, wherein at least one of the bolts comprises a multi-jackbolt tensioner.

5. The cover die holder block of claim 3, wherein at least one of the bolts extends through the projection and the recess.

6. The cover die holder block of claim 1, wherein the second cover die holder block component has defined therein: an additional portion of the cover die holder block pocket surface.

7. The cover die holder block of claim 1, wherein the second cover die holder block component has defined therein: additional portions of the two opposing lock faces.

8. The cover die holder block of claim 1, wherein each said portion of the lock face defined in the first cover die holder block component comprises greater than 50 percent of a total area of the lock face.

9. The cover die holder block of claim 1, wherein each said portion of the lock face defined in the first cover die holder block component comprises greater than 60 percent of a total area of the lock face.

10. The cover die holder block of claim 1, wherein each said portion of the lock face defined in the first cover die holder block component comprises greater than 70 percent of a total area of the lock face.

11. The cover die holder block of claim 1, wherein each said portion of the lock face defined in the first cover die holder block component comprises greater than 80 percent of a total area of the lock face.

12. A cover die holder block for a high-pressure die casting apparatus, the cover die holder block comprising: a first cover die holder block component having defined therein at least a portion of a cover die holder block pocket surface configured to accommodate at least one die insert defining a mold surface, one or more surfaces of said at least a portion of the cover die holder block pocket surface facing a parting plane of the cover die holder block, and at least portions of two opposing lock faces adjacent the cover die holder block pocket surface; and a second cover die holder block component, the first and second cover die holder block components being separately fabricated and being connected to yield the cover die holder block.

13. The cover die holder block of claim 12, wherein each of the first cover die holder block component and the second cover die holder block component is fabricated from a respective, single piece of material.

14. The cover die holder block of claim 12, wherein the first cover die holder block component and the second cover die holder block component are connected by bolts.

15. The cover die holder block of claim 14, wherein at least one of the bolts comprises a multi-jackbolt tensioner.

16. The cover die holder block of claim 12, wherein the first cover die holder block component comprises a recess that is shaped to receive a projection extending from the second cover die holder block component.

17. The cover die holder block of claim 16, wherein the projection and recess are located behind the lock face in a direction of largest stress applied to the lock face during operation.

18. The cover die holder block of claim 12, wherein the second cover die holder block component has defined therein: an additional portion of the cover die holder block pocket surface.

19. The cover die holder block of claim 12, wherein the second cover die holder block component has defined therein: additional portions of the two opposing lock faces.

20. The cover die holder block of claim 12, wherein each said portion of the lock face defined in the first cover die holder block component comprises greater than 60 percent of a total area of the lock face.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Embodiments will now be described more fully with reference to the accompanying drawings in which:

[0021] FIG. 1 is a perspective view of a cover die holder block forming part of a die assembly of a high-pressure die casting apparatus;

[0022] FIG. 2 is a sectional side view of cover die holder block of FIG. 1, taken along the indicated section line;

[0023] FIG. 3 is a perspective view of another embodiment of a cover die holder block;

[0024] FIG. 4 is an exploded perspective view of the cover die holder block of FIG. 3;

[0025] FIG. 5 is another perspective view of the cover die holder block of FIG. 3, with internal surfaces formed in a portion thereof shown as hidden lines;

[0026] FIG. 6 is another perspective view of the cover die holder block of FIG. 4, with internal surfaces formed in a portion thereof shown as hidden lines;

[0027] FIG. 7 is a side view of a multi-jackbolt tensioner for use with the cover die holder block of FIG. 3;

[0028] FIG. 8 is a front view of the multi-jackbolt tensioner of FIG. 7;

[0029] FIGS. 9A and 9B are sectional side views of an exemplary die assembly, in intermediate and closed configurations, respectively, showing calculated deformation experienced by the exemplary die assembly during operation, in accordance with an example;

[0030] FIGS. 10A,10B and 10C are perspective views of exemplary cover die holder blocks, in accordance with another example;

[0031] FIG. 11 is an enlarged perspective view of the exemplary cover die holder block of FIG. 10B;

[0032] FIGS. 12A and 12B are perspective views of a first cover die holder block component and a portion of a second cover die holder block component, respectively, forming part of the exemplary cover die holder block of FIG. 11;

[0033] FIG. 13 is an enlarged perspective view of the exemplary cover die holder block of FIG. 10C;

[0034] FIG. 14 is a perspective view of a portion of the exemplary cover die holder block of FIG. 13;

[0035] FIGS. 15A, 15B and 15C are views of the exemplary cover die holder blocks of FIGS. 10A,10B and 10C, respectively, showing calculated deformation experienced by the cover die holder blocks during operation; and

[0036] FIGS. 16A, 16B and 16C are views of the exemplary cover die holder blocks of FIGS. 10A,10B and 10C, respectively, showing calculated stress experienced by the cover die holder blocks during operation.

DETAILED DESCRIPTION OF EMBODIMENTS

[0037] The foregoing summary, as well as the following detailed description of embodiments will be better understood when read in conjunction with the appended drawings. As used herein, an element or feature introduced in the singular and preceded by the word a or an should be understood as not necessarily excluding the plural of the elements or features. Further, references to one example or one embodiment are not intended to be interpreted as excluding the existence of additional examples or embodiments that also incorporate the described elements or features. Reference herein to example means that one or more feature, structure, element, component, characteristic and/or operational step described in connection with the example is included in at least one embodiment and/or implementation of the subject matter according to the subject disclosure. Thus, the phrases an example, another example, and similar language throughout the subject disclosure may, but do not necessarily, refer to the same example. Further, the subject matter characterizing any one example may, but does not necessarily, include the subject matter characterizing any other example.

[0038] Unless explicitly stated to the contrary, examples or embodiments comprising or having or including an element or feature or a plurality of elements or features having a particular property may include additional elements or features not having that property. Also, it will be appreciated that the terms comprises, has, includes means including but not limited to and the terms comprising, having and including have equivalent meanings.

[0039] As used herein, the term and/or can include any and all combinations of one or more of the associated listed elements or features.

[0040] It will be understood that when an element or feature is referred to as being on, attached to, affixed to, connected to, coupled with, contacting, etc. another element or feature, that element or feature can be directly on, attached to, connected to, coupled with or contacting the other element or feature or intervening elements may also be present. In contrast, when an element or feature is referred to as being, for example, directly on, directly attached to, directly affixed to, directly connected to, directly coupled with or directly contacting another element of feature, there are no intervening elements or features present.

[0041] It will be understood that spatially relative terms, such as under, below, lower, over, above, upper, front, back and the like, may be used herein for ease of description to describe the relationship of an element or feature to another element or feature as illustrated in the figures. The spatially relative terms can however, encompass different orientations in use or operation in addition to the orientation depicted in the figures.

[0042] Reference herein to configured denotes an actual state of configuration that fundamentally ties the element or feature to the physical characteristics of the element or feature preceding the phrase configured to.

[0043] Unless otherwise indicated, the terms first, second, etc. are used herein merely as labels, and are not intended to impose ordinal, positional, or hierarchical requirements on the items to which these terms refer. Moreover, reference to a second item does not require or preclude the existence of a lower-numbered item (e.g., a first item) and/or a higher-numbered item (e.g., a third item).

[0044] As used herein, the terms approximately and about represent an amount close to the stated amount that still performs the desired function or achieves the desired result. For example, the terms approximately and about may refer to an amount that is within engineering tolerances that would be readily appreciated by a person skilled in the art.

[0045] Turning now to FIGS. 1 and 2, a cover die holder block for a high-pressure die casting apparatus is shown and is generally indicated by reference numeral 20. Cover die holder block 20 forms part of a die assembly (not shown) of the high-pressure die casting apparatus. The cover die holder block 20 forms part of a cover die (not shown), which is stationary in use and which is used with an opposing, movable ejector die (not shown) and one or more other moveable dies (not shown), such as slide dies, that together form the die assembly. When the dies of the die assembly are brought into a closed configuration, they define a mold cavity for forming a metal casting (not shown). Once the metal casting has been formed, the moveable dies are moved generally away from the cover die holder block 20 to bring the die assembly into an open configuration, to allow the metal casting to be removed. In the example shown, the cover die holder block 20 is sized and shaped to form a casting in the shape of a large automotive structural component, however it will be understood that the cover die holder block 20 may alternatively be configured to form large castings of other shapes.

[0046] The cover die holder block 20 has a unitary construction and is fabricated from a single piece of material and, in this embodiment the cover die holder block 20 is fabricated by machining a single block of steel. In the example shown, and with reference to the coordinate axes x, y and z defining the cartesian coordinate space xyz, the cover die holder block 20 has a length of about 3.7 m that extends in the x direction, a width of about 2.9 m that extends in the y direction, a height of about 1.0 m that extends in the z direction, and a mass of about 138,000 pounds. The cover die holder block 20 is fabricated from a single block of steel having a mass of about 182,000 pounds.

[0047] The cover die holder block 20, which has a parting plane parallel to the xy plane, has a mold-facing surface 30 formed therein by machining. The mold-facing surface 30 comprises a cover die holder block pocket surface 32 in which recesses, commonly referred to as pockets, are defined for accommodating one or more replaceable die inserts (not shown). As will be understood, the die inserts define a portion of the surface of the mold cavity. A bore hole 34 is formed through the cover die holder block 20 and defines an aperture on the die-facing surface 30. The bore hole 34 is sized to accommodate a shot sleeve (not shown) through which a volume of liquid metal is pushed into the mold cavity during operation.

[0048] The mold-facing surface 30 also comprises two (2) generally opposing lateral surfaces, namely lock faces 50 (sometimes referred to as slide lock surfaces or cover lock surfaces). The lock faces 50 experience particularly high stresses in the lateral direction (namely, in a direction along the x axis) during operation. As will be understood, the high stresses result from lateral forces applied by moveable slide dies (not shown), which are positioned against these areas of the mold-facing surface 30 during operation and are forced against the lock faces 50 upon high-pressure injection of liquid metal into the mold cavity. Additionally, due to greater thermal expansion experienced by the moveable slide dies relative to the cover die during operation, the high stresses experienced at the lock faces 50 tend to increase with successive casting cycles.

[0049] As will be understood, although advantageously being capable of forming a large automotive structural component in a single casting step, the large size and mass of the cover die holder block 20 present several engineering issues.

[0050] First, because the holder block 20 has a unitary construction and is fabricated from a single piece of material, namely steel, the ability to manufacture the cover die holder block 20 depends on availability of a suitably sized block of steel. Due to its large size, there are currently few suppliers of steel raw material globally capable of supplying such a suitably sized block. As a result, the lead time (namely, the time between placement of the order and delivery) for the raw material necessary to manufacture the cover die holder block 20 can be unacceptably long.

[0051] Second, the dimensions and weight of the steel block from which the cover die holder block 20 is fabricated require special machining equipment to carry out the fabrication. Machining equipment capable of machining a single item having the large dimensional area of the steel block, while simultaneously supporting the large weight of the steel block, can be difficult to obtain.

[0052] Third, the large weight of the cover die holder block 20 exceeds the general weight limit of 45,000 pounds for road transportation by conventional tractor-trailer truck. This renders transportation of the cover die holder block 20, such as from a die manufacturer to an end user, difficult and costly. Additionally, the large weight of the cover die holder block 20 requires special handling equipment, such as special heavy-lift cranes, etc., at both the manufacturing facility and the end user's facility, which can be difficult, impractical and costly to obtain if not already available.

[0053] To overcome at least these engineering issues, there is provided a cover die holder block for a high-pressure die casting apparatus that has a generally modular construction, and consists of a plurality of smaller cover die holder block components that are fabricated separately and are subsequently connected to yield the assembled cover die holder block. As will be appreciated, owing to their smaller size, the cover die holder block components can advantageously be manufactured and transported separately, and hence more easily and at lower cost than the single, large cover die holder block 20. Additionally, and as will be appreciated, owing to their smaller size, the cover die holder block components can each advantageously be manufactured from steel block of smaller size, which is more readily available and hence has shorter lead time than the single, large steel block required for manufacture of the cover die holder block 20.

[0054] At the same time, although being fabricated from a plurality of smaller components, the multi-component cover die holder block is advantageously capable of forming the same large, single casting as the cover die holder block 20.

[0055] FIGS. 3 to 6 show a cover die holder block for a high-pressure die casting apparatus, and which is generally indicated by reference numeral 120. Similar to cover die holder block 20 described above, cover die holder block 120 forms part of a cover die (not shown) of a die assembly (not shown) of the high-pressure die casting apparatus. In the example shown, the cover die holder block 120 is sized and shaped to form a casting in the shape of a large automotive structural component, however it will be understood that the cover die holder block 120 may alternatively be configured to form castings of other shapes.

[0056] The cover die holder block 120 comprises two (2) cover die holder block components, namely a first cover die holder block component 122 and a second cover die holder block component 124, which when connected yield the assembled cover die holder block 120. In the example shown, the first cover die holder block component 122 is smaller in size than the second cover die holder block component 124.

[0057] Each of the first cover die holder block component 122 and the second cover die holder block component 124 is fabricated from a respective, single piece of material, and in this embodiment each of the cover die holder block components 122 and 124 is fabricated by machining a single block of steel. In the example shown, the cover die holder block 120 has the same dimensions as the cover die holder block 20 described above. With reference to the coordinate axes x, y and z defining the cartesian coordinate space xyz, the cover die holder block 120 has a length of about 3.7 m that extends in the x direction, a width of about 2.9 m that extends in the y direction, a height of about 1.0 m that extends in the z direction, and an assembled mass of about 138,000 pounds.

[0058] The cover die holder block 120, which has a parting plane parallel to the xy plane, has a mold-facing surface 130 formed therein by machining. The mold-facing surface 130 comprises a cover die holder block pocket surface 132 in which recesses, commonly referred to as pockets, are defined for accommodating one or more replaceable die inserts (not shown). As will be understood, the die inserts define a portion of the surface of the mold cavity. A bore hole 134 is formed through one or both of cover die holder block components 122 and 124 and defines an aperture on the die-facing surface 30. The bore hole 134 is sized to accommodate a shot sleeve 136 through which a volume of liquid metal is pushed into the mold cavity during operation. In this embodiment, the bore hole is formed through the first cover die holder block component 122.

[0059] In the example shown, each of the cover die holder block components 122 and 124 has a portion of the cover die holder block pocket surface 132 defined therein. Specifically, the first cover die holder block component 122 has a first cover die holder block pocket surface portion 142 formed therein, and the second cover die holder block component 124 has a second cover die holder block pocket surface portion 144 formed therein. The first and second cover die holder block pocket surface portions 142 and 144 face the parting plane, and together define the cover die holder block pocket surface 132 of the cover die holder block 120. In the example shown, the first and second cover die holder block pocket surface portions 142 and 144 are parallel to the parting plane. The first cover die holder block pocket surface portion 142 is greater than 50 percent of the total area of the cover die holder block pocket surface 132, and preferably the first cover die holder block pocket surface portion 142 is greater than 60 percent of the total area of the cover die holder block pocket surface 132, more preferably greater than 70 percent, still more preferably greater than 80 percent of the total area of the cover die holder block pocket surface 132.

[0060] The mold-facing surface 130 also comprises two (2) generally opposing lateral surfaces, namely lock faces 150 (sometimes referred to as slide lock surfaces or cover lock surfaces). The lock faces 150 experience particularly high stresses in the lateral direction (namely, in a direction along the x axis) during operation. As will be understood, the high stresses result from lateral forces applied by moveable slide dies (not shown), which are positioned against these areas of the mold-facing surface 130 during operation and are forced against the lock faces 150 upon high-pressure injection of liquid metal into the mold cavity. Additionally, due to greater thermal expansion experienced by the moveable slide dies relative to the cover die during operation, the high stresses experienced at the lock faces 150 tend to increase with successive casting cycles.

[0061] In the example shown, each of the cover die holder block components 122 and 124 has a portion of each lock face 150 defined therein. Specifically, the first cover die holder block component 122 has two (2) generally opposing primary lock face portions 152 formed therein, and the second cover die holder block component 124 has two (2) generally opposing secondary lock face portions 154 formed therein. Each lock face 150 of the cover die holder block 120 is defined by one (1) primary lock face portion 152 and one (1) secondary lock face portion 154, with the primary lock face portion 152 and the secondary lock face portion 154 being discontinuous and non-coplanar. Each primary lock face portion 152 is greater than 50 percent of the total area of the lock face 150, and preferably each primary lock face portion 152 is greater than 60 percent of the total area of the lock face 150, more preferably greater than 70 percent, still more preferably greater than 80 percent, and most preferably greater than 85 percent of the total area of the lock face 150, as in the example shown in FIGS. 3 to 6. In the example shown, two (2) replaceable primary lock wear plates 156a are positioned against the primary lock face portions 152, and two (2) replaceable secondary lock wear plates 156b are positioned against the secondary lock face portions 154.

[0062] The first cover die holder block component 122 and the second cover die holder block component 124 are connected by a plurality of bolts 160 extending therebetween, so as to form a bolted joint 158. The cover die holder block components 122 and 124 are sized and shaped such that the surface of the joint 158 extends in generally linearly across the mold-facing surface 130, and then contains a jog to extend through the volume of material behind the primary lock face portions 152, as described further below.

[0063] In the example shown, the first cover die holder block component 122 and the second cover die holder block component 124 are connected by thirteen (13) bolts 160 extending therebetween, with each bolt 160 comprising a multi-jackbolt tensioner 162.

[0064] The multi-jackbolt tensioner 162 may be better seen in FIGS. 7 and 8. The multi-jackbolt tensioner 162 comprises an annular body 164, and a plurality of smaller bolts 166 each comprising a commensurately sized head 168 and each extending through the body 164 and abutting a washer 172 fabricated of a hardened material. As will be understood, although the diameter of bolt 160 is relatively large, the multi-jackbolt tensioner 162 can be secured using a conventional hand tool, such as a torque wrench, to tighten the heads 168 of the bolts 166, which enables the multi-jackbolt tensioner 162 to apply significantly high torque to the bolt 160 in a facile manner. The multi-jackbolt tensioner 162 may be, for example, a SuperBolt tensioner, manufactured by Superbolt Incorporated of Pennsylvania, U.S.A.

[0065] Turning again to FIGS. 3 to 6, the second cover die holder block component 124 has two (2) projections 180 protruding therefrom and, in the example shown, each projection 180 has a generally L-shaped profile in the xz plane. The first cover die holder block component 122 has two (2) correspondingly shaped recesses 182 formed therein, each of which is sized and shaped to receive a projection 180. As will be understood, when the cover die holder block components 122 and 124 are connected to form the assembled cover die holder block 120, the projections 180 matingly engage the recesses 182 and provide resistance to the high lateral stresses that exist in the volume of the first cover die holder block component 122 behind the primary lock face portions 152.

[0066] Further, the cover die holder block components 122 and 124 are configured such that at least some of the bolts 160 extend through second apertures 186 defined in the second cover die holder block component 124, across the joint 158 near and directly behind the lock faces 150 in a direction along the x axis, and into first apertures 188 defined in the first cover die holder block component 122, to provide resistance to the high lateral stresses that exist in the volume of the first cover die holder block component 122 behind the primary lock face portions 152.

[0067] Additionally, the cover die holder block components 122 and 124 are configured such that the joint 158 defines only a single, normal surface 190 oriented normally (namely, perpendicularly) to the direction of the laterally applied stresses experienced at the lock faces 150 (namely, in a direction along the x axis) along any line parallel to the x axis passing through any surface of the lock face 150, on either half of the cover die holder block 120. In particular, the normal surface 190 is located directly behind the lock face 150, and specifically behind a portion of the primary lock face portion 152, in a direction along the x axis. Further, the area of each normal surface 190 is small relative to the area of the primary lock face portion 152, and each normal surface 190 is offset in a direction parallel to the normal surface (namely, in a direction along the y axis) far from the point P, which is the point where the geometric center of the primary lock face portion 152 is projected onto the parting plane, and which experiences the greatest deformation during operation (see, for example, FIG. 15A).

[0068] As will be appreciated, this configuration of the cover die holder block components 122 and 124 and joint 158 advantageously allows deformation of the first cover die holder block component 122 near the lock faces 150 during operation to be reduced, and/or to be of equal magnitude to deformation experienced by a single piece cover die holder block, such as the single piece cover die holder block 20.

[0069] Further, the cover die holder block components 122 and 124 are configured such that the portion of the joint 158 extending across the cover die holder block pocket surface 132 is parallel to the direction of the laterally applied stresses experienced at the lock faces 150. As a result, any likelihood of separation of the cover die holder block components 122 and 124 during operation is reduced or eliminated.

[0070] In use, the cover die holder block 120 is assembled by connecting the first cover die holder block component 122 and the second cover die holder block component 124 with bolts 160. The cover die holder block 120 may be assembled in situ on the high-pressure die casting apparatus, or generally near the location of the high-pressure die casting apparatus, such that significant transportation of the assembled cover die holder block 120 for installation at the high-pressure die casting apparatus is not required.

[0071] As will be appreciated, the cover die holder block 120 is configured such that i) a majority of the cover die holder block pocket surface 130, and ii) a majority of each lock face 150, are entirely defined in the first cover die holder block component 122, which is fabricated from the same, single piece of material. Additionally, and as will be appreciated, the joint 158 defines only a single, normal surface 190 oriented perpendicularly to the direction of the laterally applied stress experienced at the lock face 150 (namely, in a direction along the x axis) along any line parallel to the x axis passing through the lock face 150, on either half of the cover die holder block 120. The are of the normal surface 190 is small relative to the area of the primary lock face portion 152, and is distal from the point P, which is the point where the geometric center of the primary lock face portion 152 is projected onto the parting plane. By virtue of this construction, the cover die holder block 120 is advantageously immune to i) unacceptable joint separation, and ii) unacceptable deformation, that would otherwise occur due to the high stresses experienced during operation, in particular when the die assembly is in the closed configuration.

[0072] The configuration of the cover die holder block 120 is not limited to the embodiment described above. For example, although in the embodiment described above, the cover die holder block 120 comprises two (2) cover die holder block components, namely the first cover die holder block component 122 and the second cover die holder block component 124, in other embodiments, the cover die holder block may comprise more than two (2) cover die holder block components.

[0073] Although in the embodiment described above, each of the cover die holder block components 122 and 124 has a portion of the cover die holder block pocket surface 132 of the cover die holder block 120 defined therein, in other embodiments, only one of the cover die holder block components may alternatively have the entirety of the cover die holder block pocket surface of the cover die holder block defined therein.

[0074] Although in the embodiment described above, each of the cover die holder block components 122 and 124 has a portion of each lock face 150 of the cover die holder block 120 defined therein, in other embodiments, only one of the cover die holder block components may alternatively have the entirety of each lock face defined therein.

[0075] Although in the embodiment described above, the first cover die holder block component 122 and the second cover die holder block component 124 are connected by thirteen (13) bolts 160 extending therebetween, in other embodiments, the first cover die holder block component and the second cover die holder block component may alternatively be connected by fewer than thirteen (13) bolts or greater than thirteen (13) bolts.

[0076] Although in the embodiment described above, the second cover die holder block component 124 has two (2) projections 180 protruding therefrom and the first cover die holder block component 122 has two (2) correspondingly shaped recesses 182 formed therein, each of which is sized and shaped to receive a projection 180, in other embodiments, the second cover die holder block component may alternatively have more than two (2) projections protruding therefrom and the first cover die holder block component may alternatively have more than two (2) correspondingly shaped recesses formed therein.

[0077] Although in the embodiment described above, each of the projections 180 protruding from the second cover die holder block component 124 has a generally L-shaped profile, in other embodiments, each of the projections may alternatively be differently shaped.

[0078] The following examples illustrate application of, and experimental test data obtained during development of, one or more of the above-described embodiments.

EXAMPLE 1

[0079] In this example, deformation experienced by an exemplary die assembly comprising a single-piece cover die holder block during operation was calculated using finite element analysis (FEA).

[0080] FIG. 9A shows the exemplary die assembly, which is generally indicated by reference numeral 218. The exemplary die assembly 218 is shown in FIG. 9A in an intermediate configuration of the casting cycle, namely a configuration that is between the open configuration and the closed configuration, and before any clamping force has been applied thereto and prior to injection of liquid metal.

[0081] The die assembly 218 comprises two opposing main dies, namely a fixed cover die comprising a cover die holder block 220, and a movable ejector die comprising a moveable ejector die holder block 222. The die assembly 218 further comprises two (2) movable slide dies 224.

[0082] The cover die holder block 220 is generally similar to the cover die holder block 20 described above and with reference to FIGS. 1 and 2, and has a unitary construction and is fabricated from a single piece of material, namely steel, and has a cover die holder block pocket surface 232 formed therein by machining. The cover die holder block pocket surface 232 has recesses or pockets defined therein for accommodating replaceable die inserts 234, 236 and 238. As will be understood, the die inserts 234, 236 and 238 define a portion of the surface of the mold cavity defined by the die assembly 218. The cover die holder block pocket surface 232 has two (2) lock faces 250 defined therein. In the example shown, two (2) replaceable lock wear plates 252 are positioned against the lock faces 250. Each slide die 226 also has a corresponding replaceable wear plate installed thereon in the form of a slide wear plate 256, which is configured to abut a respective lock wear plate 252 during operation.

[0083] FIG. 9B shows the die assembly 218 in the closed configuration. As will be understood, in the closed configuration, a clamping force is applied generally along the z axis to clamp the ejector die holder block 222 and the cover die holder block 220 together, with the slide dies 224 positioned therebetween. Once the clamping force has been applied, a volume of liquid metal is injected under high pressure into the mold cavity to form a metal casting.

[0084] The calculated deformation experienced by the die assembly 218 in the closed configuration is shown in FIG. 9B, as indicated by the color scale. In the cover die holder block 220, the lock faces 250, and the volumes of material behind the lock faces 250, experience greater deformation than other portions of the cover die holder block 220, with the highest amounts of deformation on the lock faces 250 being adjacent the parting plane. In addition to the color scale, the calculated deformation experienced by the die assembly 218 is visible (although exaggerated) by comparing the shape outlines of the components of the die assembly 218 in FIGS. 9A and 9B. As can be seen, in the cover die holder block 220, the greatest amount of deformation is observed on the outer surfaces of the cover die holder block 220 behind the lock faces 250 and at the parting plane, which results from the high stresses along the x axis experienced by the cover die holder block 220 in the closed configuration.

EXAMPLE 2

[0085] In this example, stress and deformation experienced by three (3) exemplary cover die holder blocks during operation were calculated using FEA.

[0086] FIGS. 10A to 10C show the three (3) exemplary cover die holder blocks used in this example, namely cover die holder block 20, cover die holder block 320, and cover die holder block 420, respectively.

[0087] The cover die holder block 20, which has been described above and with reference to FIGS. 1 and 2, has a unitary construction and is fabricated from a single piece of material, namely steel.

[0088] The cover die holder block 320 may be better seen in FIGS. 11, 12A and 12B. Cover die holder block 320 has a modular construction and comprises three (3) cover die holder block components, namely a first cover die holder block component 322, a second cover die holder block component 324 and a third cover die holder block component 326, which when connected yield the assembled cover die holder block 320. In the example shown, the first and third cover die holder block components 322 and 326 have generally the same dimensions, and are smaller in size than the second cover die holder block component 324.

[0089] Each of the first cover die holder block component 322, the second cover die holder block component 324 and the third cover die holder block component 326 is fabricated from a respective, single piece of material, and in the example shown, each of the cover die holder block components 322, 324 and 326 is fabricated by machining a respective single block of steel. The assembled cover die holder block 320 has the same dimensions as the cover die holder block 20 described above.

[0090] The cover die holder block 320 has a mold-facing surface 330 formed therein by machining. The mold-facing surface 330 comprises a cover die holder block pocket surface 332 in which recesses, commonly referred to as pockets, are defined for accommodating one or more replaceable die inserts (not shown). In the example shown, the second cover die holder block component 324 has the entirety of the cover die holder block pocket surface 332 defined therein. A bore hole 334 is formed through the second cover die holder block component 324.

[0091] The mold-facing surface 330 also comprises (2) generally opposing lateral surfaces, namely lock faces 350 (sometimes referred to as slide lock surfaces or cover lock surfaces). In the example shown, each of the first and third cover die holder block components 322 and 326 has an entire lock face 350 defined therein.

[0092] The first cover die holder block component 322, the second cover die holder block component 324 and the third cover die holder block component 326 are connected by a plurality of bolts 360. In particular, the first cover die holder block component 322 and the second cover die holder block component 324 are connected by a first plurality of bolts 360 extending therebetween, to form a bolted joint 362 between the first cover die holder block component 322 and the second cover die holder block component 324. Although not shown, the third cover die holder block component 326 and the second cover die holder block component 324 are connected by a second plurality of bolts 360 extending therebetween, to form a bolted joint 364 between the second cover die holder block component 324 and the third cover die holder block component 326. The cover die holder block components 322, 324 and 326 are sized and shaped such that the bolted joints 362 and 364 extend in a direction that is generally parallel to the lock faces 350.

[0093] In the example shown, the first cover die holder block component 322 and the second cover die holder block component 324 are connected by five (5) bolts 360 extending therebetween, with each bolt 360 comprising a multi-jackbolt tensioner 368. The multi-jackbolt tensioner 368 may for example be a SuperBolt tensioner, manufactured by Superbolt Incorporated of Pennsylvania, U.S.A.

[0094] As can be seen from FIGS. 12A and 12B, the first cover die holder block component 322 and the second cover die holder block component 324 are configured such that the five (5) bolts 360 connecting the cover die holder block components 322 and 324 extend in a direction that is generally parallel to a direction of applied force against the lock face 350. As will be appreciated, this configuration allows the tensile force provided by the bolts 360 to directly oppose the force applied against the lock face 350. Further, the cover die holder block components 322, 324 and 326 are configured such that each joint 362 and 364 is located near a respective lock face 350. Although not shown in FIGS. 12A and 12B, the third cover die holder block component 326 and the second cover die holder block component 324, and the joint 364 therebetween, are configured analogously.

[0095] Turning now to FIGS. 13 and 14, the cover die holder block 420 is shown in greater detail. Cover die holder block 420 has a modular construction and comprises four (4) cover die holder block components, namely a first cover die holder block component 422, a second cover die holder block component 424, a third cover die holder block component 426 and a fourth cover die holder block component 428, which when connected yield the assembled cover die holder block 420.

[0096] Each of the first cover die holder block component 422, the second cover die holder block component 424, the third cover die holder block component 426 and the fourth cover die holder block component 428 is fabricated from a respective, single piece of material, and in the example shown, each of the cover die holder block components 422, 424, 426 and 428 is fabricated by machining a respective single block of steel. The assembled cover die holder block 420 has generally the same dimensions as the cover die holder block 20 described above.

[0097] The cover die holder block 420 has a mold-facing surface 430 formed therein by machining. The mold-facing surface 430 comprises a cover die holder block pocket surface 432 in which recesses, commonly referred to as pockets, are defined for accommodating one or more replaceable die inserts (not shown). In the example shown, each of the third and fourth cover die holder block components 426 and 428 has a portion of the cover die holder block pocket surface 432 defined therein. A bore hole 434 is formed through cover die holder block components 424, 426 and 428. The bore hole 434 is sized to accommodate a shot sleeve 436 through which a volume of liquid metal is pushed into the mold cavity during operation.

[0098] The mold-facing surface 430 also comprises (2) generally opposing lateral surfaces, namely lock faces 450 (sometimes referred to as slide lock surfaces or cover lock surfaces). In the example shown, each of the third and fourth cover die holder block components 426 and 428 has an entire lock face 450 defined therein.

[0099] The third cover die holder block component 426 and the fourth cover die holder block component 428 are connected by two (2) bolts 460 extending therebetween, so as to form a bolted joint 462 therebetween. The third and fourth cover die holder block components 426 and 428 are sized and shaped such that the bolted joint 462 extends in a direction that is generally parallel to the lock faces 450. Each bolt 460 comprises a multi-jackbolt tensioner 468. The multi-jackbolt tensioner 468 may for example be a SuperBolt tensioner, manufactured by Superbolt Incorporated of Pennsylvania, U.S.A.

[0100] The first and second cover die holder block components 422 and 424 and 428 are connected by a plurality of conventional bolts (not shown) extending therebetween. Although not shown, the first and second cover die holder block components 422 and 424 and the third and fourth cover die holder block components 426 and 428 are connected by a further plurality of conventional bolts (not shown).

[0101] When connected, the first and second cover die holder block components 422 and 424 are configured to effectively serve as a backing plate that provides resistance to lateral stresses experienced by the third and fourth cover die holder block components 426 and 428. As shown in FIG. 14, each of the cover die holder block components 422, 424, 426 and 428 has interlocking features integrally formed therein that enable the first and second cover die holder block components 422 and 424 to engage the third and fourth cover die holder block components 426 and 428 to provide resistance to lateral stresses. In particular, the first cover die holder block component 422 has: i) first corner tabs 472 protruding therefrom, which are sized and shaped to be received in a corresponding pocket (not shown) formed in the underside of the third cover die holder block component 426 and the fourth cover die holder block component 428; ii) a first longitudinal side channel 474 formed therein, which is sized and shaped to receive a corresponding first longitudinal tab 476 protruding from the underside of each of the third cover die holder block component 426 and the fourth cover die holder block component 428; and iii) corresponding first transverse side tabs 478 protruding therefrom, which are sized and shaped to be received in corresponding transverse channels (not shown) formed in the underside of the third cover die holder block component 426 and the fourth cover die holder block component 428.

[0102] The second cover die holder block component 424 has: i) first traverse side tabs 482 protruding therefrom, which are sized and shaped to be received in corresponding transverse channels (not shown) formed in the underside of the third cover die holder block component 426 and the fourth cover die holder block component 428; and ii) a second longitudinal side channel 484 formed therein, which is sized and shaped to receive a corresponding second longitudinal tab 486 protruding from the underside of each of the third cover die holder block component 426 and the fourth cover die holder block component 428.

[0103] For simplicity, the two (2) bolts 460 extending therebetween the third and fourth cover die holder block components 426 and 428 are not shown in FIG. 14.

[0104] FIGS. 15A to 15C show the calculated deformation experienced by each of the cover die holder blocks 20, 320 and 420 when the die assembly is in the closed configuration, and upon high pressure injection of liquid metal. FIGS. 16A to 16C show the calculated stress experienced by each of the cover die holder blocks 20, 320 and 420 when the die assembly is in the closed configuration, and upon high pressure injection of liquid metal.

[0105] As can be seen in FIG. 15A, the single-piece cover die holder block 20 experienced high deformation in the volume of material behind the lock face 50. The amount of deformation is still within acceptable operational tolerances for the die assembly. (Although not shown, the other half of the cover die holder block 20 would be expected to exhibit analogous, symmetric behavior).

[0106] The three (3)-piece cover die holder block 320, shown in FIG. 15B, experienced severe deformation in the first cover die holder block component 322, and in particular in the volume of material behind the lock face 350. Further, the cover die holder block 320 experienced separation between the first and second cover die holder block components 322 and 324, resulting in formation of a gap at the joint 362. The amount of deformation, and the existence of a gap, are both outside of acceptable operational tolerances for the die assembly, and as a result the design of the cover die holder block 320 is a failure. (Although not shown, the other half of the cover die holder block 320 would be expected to exhibit analogous, symmetric behavior).

[0107] The four (4)-piece cover die holder block 420, shown in FIG. 15C, experienced severe deformation in the third and fourth cover die holder block components 426 and 428, and in particular in the volume of material behind each of the lock faces 450. Further, the cover die holder block 420 experienced separation between the third and fourth cover die holder block components 426 and 428, resulting in formation of a gap at the joint 462. The amount of deformation, and the existence of a gap, are both outside of acceptable operational tolerances for the die assembly, and as a result the design of the cover die holder block 420 is a failure.

[0108] Although embodiments have been described above with reference to the accompanying drawings, those of skill in the art will appreciate that variations and modifications may be made without departing from the scope thereof as defined by the appended claims.