BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a sectional view of a die casting system in which single-piece cooling blocks of the present invention are used.
FIG. 2 shows a perspective view of two joined single-piece cooling blocks, a sprue block and a runner block, of the present invention.
FIG. 3A shows a front view of the single-piece sprue block of FIG. 2.
FIG. 3B shows a sectional view of the sprue block of FIG. 3A taken along section 3B-3B.
FIG. 3C shows a partially cut-away sectional view of the sprue block of FIG. 3A taken along section 3C-3C.
FIG. 3D shows a front view of the single-piece spreader block of FIG. 2.
FIG. 3E shows a sectional view of the spreader block of FIG. 3D taken along section 3E-3E.
FIG. 4 shows a sectional view of the cooling blocks of FIG. 2 taken along section 4-4.
FIG. 5 shows a sectional view of the cooling blocks of FIG. 2 taken along section 5-5.
DETAILED DESCRIPTION
FIG. 1 shows a sectional view of die casting system 10 in which the present invention is used. The invention is typically used in zinc or magnesium hot chamber die casting operations, and the invention is hereinafter described in reference to die casting. In other embodiments, however, the present invention can also be used in cold chamber die casting operations, or injection molding applications. Die casting system 10 includes stationary die half 12 and moving die half 14. Stationary die half 12 and moving die half 14 together comprise mold cavity 16, which has the shape of an object that can be molded with die casting system 10. Die casting system 10 also includes cooling blocks 18A and 18B (collectively referred to as cooling block 18 when assembled), which are used to control the flow of molten metal into die cavity 16. Molten metal from crucible 20 is injected with piston 22 into die casting system 10 through nozzle 24 and sprue 26 of cooling block 18A. As molten metal enters cooling block 18A through sprue 26, sprue post 28 of cooling block 18B directs the flow of the molten metal into runner 30. Runner 30 directs flow of molten metal to outlet 32, into die runner 34 and into mold cavity 16. Cooling blocks 18A and 18B, movable die half 14 and stationary die half 12 also include additional channels (not shown) for circulating cooling fluid, such as water, through cooling blocks 18A and 18B in order to control the temperature of the molten metal and, hence, its flow and cooling characteristics. Cooling blocks 18A and 18B provide improved heat dissipation for the injected metal as it enters die cavity 16, which accordingly reduces the cycle time required to cool the injected molten metal when creating articles of manufacture in die cavity 16. Once the molten metal is fully injected into die cavity 16 and properly cooled, movable die half 14 is pulled away from stationary die half 12 so that the cooled molten metal having the shape of die cavity 16 can be removed using ejectors 36.
FIG. 2 shows a perspective view of cooling block 18, including cooling blocks 18A and 18B of the present invention. Cooling block 18B comprises spreader block 40 and cooling block 18A comprises sprue block 38, which includes mounting holes 48A-48D that are used to couple sprue block 38 to stationary die half 12 with, for example, threaded fasteners. Sprue block 38 and spreader block 40 each include a system of cooling fluid channels for controlling the temperature of molten metal, or some other such manufacturing material, entering cooling block 18. Molten metal enters cooling block 18A at sprue 26 through runner 30 and exits at outlet 32. Sprue block 38 includes a sprue block cooling system comprising a pattern of bores arranged into the surfaces of sprue block 38, of which channels 44A, 44B and 44C, and are visible in FIG. 2. Additionally, cooling bores 45A-45H are arranged around sprue 26. Spreader block 40 also includes a spreader block cooling system comprising a plurality of bores arranged into the surfaces of spreader block 40, including spreader fluid cooling channels 46A, 46B and 46C.
The cooling channels, including channels 44A-44C, channels 46A-46C and bores 45A-45H, are machined or otherwise fabricated into sprue block 38 and spreader block 40 such that sprue block 38 and spreader block 40 each can be fabricated from a single piece of material. Having sprue block 38 and spreader block 40 made from single solid pieces of material simplifies the manufacture and improves the performance of cooling block 18. For example, cooling block 18A is made from a single cast piece, rather than the typical four required to form the sprue and appropriately placed cooling channels, which saves time required for casting and machining four pieces. Solid blocks also increase the heat transfer efficiency of cooling block 18 by eliminating braze lines and other discontinuities. Also, unitary, single-piece blocks eliminate the risk of ruptures or failures of joined pieces, particularly brazed joints, caused by high pressures in casting system 10. Additionally, cooling features for runner 30 can be easily incorporated into cooling block 18B without the need of additional pieces. FIG. 2 shows cutting plane lines 4 and 5 for sectional views of cooling blocks used in FIGS. 4 and 5, in which cooling fluid channels of the present invention are further described. Cooling fluid channels, including channels 44A-44C, channels 46A-46C and bores 45A-45H are described in greater detail in FIGS. 3A-3D.
FIG. 3A shows a front view of sprue block 38 showing cooling channels 44A-44G in hidden lines and cooling bores 45A-45H. Sprue block 38 includes sprue 26, sprue block cooling channels 44A-44G, cooling bores 45A-45H, and sprue block mounting holes 48A-44D. Sprue 26 is a channel running through the center of sprue block 38 between its opposing front and rear faces through which molten metal from crucible 20 flows en route to entering die cavity 16. Sprue 26 includes nozzle seat 50, which is a beveled ring surrounding the entrance to sprue 26 and is used to facilitate connection of cooling block 18 with nozzle 24 of die casting system 10 or another source of molten metal. Sprue block cooling channels 44A-44G are used to circulate a cooling fluid, such as water, around sprue 26 in order to control heat transfer between sprue block 38 and molten metal being passed through sprue 26. Bores 45A-45H distribute cooling fluid lengthwise along sprue 26. Sprue block mounting holes 48A-48D are used to couple sprue block 38 to stationary die half 12 with threaded fasteners, or in some such similar fashion, and are typically placed in the corners of spreader block 40.
Sprue block water channels 44A-44G are machined, or otherwise fabricated, into sprue block 38 in a pattern that allows cooling fluid to circulate around sprue 26. Generally, cooling channels need not be laid out in any particular pattern, but are laid out such that cooling fluid can be distributed around a substantial portion of sprue 26 within a close proximity of sprue 26 to efficiently transfer heat, and can be systematically plugged to facilitate one-way circulation. Cooling channels 44A-44G are close enough to sprue 26 to transfer heat, but do not impart any undue stresses into block 38. In one embodiment, cooling channels 44A-44G are approximately one inch from the center of sprue 26 at their closest point. Cooling channels 44A-44G are formed into sprue block 38 such that they comprise an intersecting loop around sprue 26, and thus transfer heat from around the circumference of sprue 26. In the embodiment shown seven cooling channels are used, but in other embodiments any number of channels can be used to connect a circuit around sprue 26. As such, a plurality of the cooling channels can be plugged such that a closed-circuit for circulating cooling fluid is formed.
Cooling bores 45A-45H are drilled, or otherwise fabricated, into sprue block 38 such that each one intersects at least one of cooling channels 44A-44G. Cooling bores 45A-45H include baffles such that water circulating in cooling channels 44A-44G is deflected transversely to the flow pattern of cooling channels 44A-44G. As such, cooling fluid is directed along the length of sprue 26. Cooling bores 45A-45G are formed into the front face of sprue block 38 on the same face that sprue 26 receives material from crucible 20, the same face on which seat 50 is located. Cooling bores 45A-45H are typically distributed evenly around sprue 26 in a circular pattern. In the embodiment shown, eight cooling bores are spaced approximately forty-five degrees apart around sprue 26, and comprise approximately 7/16 inch bores spaced about one inch from the center of sprue 26. Cooling bores 45A-45H are arranged such that a line formed by the two cooling bores closest to each side of sprue block 38 is parallel to that side. For example, cooling bores 45A and 45H formaline parallel to side 52 of sprue block 38, and cooling bores 45B and 45C form a line parallel to side 54. This type of arrangement allows cooling channels 44A-44G to be formed such that they easily and simply intersect cooling bores 45A-45H.
Cooling channel 44B is formed perpendicularly into side 54 of sprue block 38 such that it intersects bore 45B. Cooling channel 44A is formed perpendicularly into side 52 such that it intersects channel 44A at bore 45B. Cooling channel 44G is formed perpendicularly into side 56 of sprue block 38 such that it intersects both bores 45A and 45H, and continues through to connect with cooling channel 44A. Cooling channel 44G is therefore perpendicular to cooling channel 44A and parallel to cooling channel 44B. Cooling channel 44E is formed perpendicularly into side 58 of sprue block 38 such that it intersects both bores 45F and 45G, and continues through to connect with cooling channel 45G. Cooling channel 44D is also formed perpendicularly into side 58 such that it intersects bore 45C and channel 44C. Cooling channel 44F is formed perpendicularly into side 56 such that it intersects both bores 45E and 45D and connects cooling channels 44E and 44D. Finally, cooling channel 44C is formed perpendicularly into side 54 of sprue block 38 such that is intersects cooling channel 44D at bore 45C. As such cooling channels 44A-44G form a loop around sprue 26 and, in conjunction with a plurality of plugs, form a one way circuit around sprue 26.
Cooling fluid can be directed into sprue block 38 at channel 44B, such as indicated with arrow A, and is able to continue into cooling channel 44A. Plug 60A is placed into the opening of channel 44A at side 52 to prevent cooling fluid from exiting sprue block 38 at side 52, and to direct the cooling fluid into cooling channel 44G. Plug 60B is placed into the opening of channel 44G at side 56 to prevent cooling fluid from exiting sprue block 38 at side 52, and to direct the cooling fluid into cooling channel 44E. Plugs 60C and 60D are placed into channels 44F and 44E, respectively, to prevent cooling fluid from exiting sprue block 38 at side 56 and side 58, and to direct cooling fluid into cooling channel 44F such that it is routed toward cooling channel 44D. Plug 60E prevents cooling fluid from exiting block 38 at side 58 and directs the cooling fluid to channel 44C. Cooling channel 44C remains unplugged whereby the cooling fluid is permitted to exit sprue block 38, as indicated by arrow B. Thus, cooling channels 44A-44G and plugs 60A-60E form a one-way circuit around sprue 26. The cooling fluid can therefore be circulated through sprue block 38 in order to cool sprue 26 around nearly its entire circumference. Sprue 26 can further be cooled along its length through cooling bores 45A-45G.
FIG. 3B shows a sectional view of sprue block 38 taken along section 3B-3B of FIG. 3A. Sprue block 38 includes cooling bores 45A-45G, of which bores 45H and 45E are seen in hidden lines. Cooling channels 44G, 44F and 44E are shown in hidden lines in FIG. 3B. Cooling bores 45A-45G extend into sprue block 38 near sprue 26, and are close enough to sprue 26 to allow for efficient heat transfer, but so as not to induce any structural stresses into block 38. In one embodiment, the centers of bores 45A-45G are approximately one inch from the center of sprue 26. Thus, bores 45A-45G extend into block 38 such that they provide heat transfer along the length of sprue 26. In one embodiment, bores 45A-45G extend approximately 1ΒΌ inch into block 38.
FIG. 3C shows a partial section view of sprue block 38 taken along section 3C-3C of FIG. 3A. Sprue block 3C includes cooling bores 45A and 45E, in which are positioned baffles 62A and 62B, respectively. Additionally, cooling bores 45B-45D and 45F-45H include baffles. Baffles 62A and 62B extend into bores 45A and 45E such that they extend past channels 44G and 44F, respectively, and extend nearly the length of bores 45A and 45E. Baffles 62A and 62B catch cooling fluid as it passes through cooling channels 44G and 44H, respectively, and direct the cooling fluid along the length of cooling bores 45A and 45E. Thus, the cooling fluid is directed along the length of sprue 26 and heat can be transferred away from sprue block 38 and the manufacturing material along the length of sprue 26. Baffles 62A and 62B also seal cooling bores 45A and 45E at the front face of sprue block 38 such that cooling fluid does not escape sprue block 38 at bores 45A and 45, but is continuously rerouted into cooling channels 44A-44G.
In other embodiments of sprue block 38, cascade type cooling can be used. In which case, a cascade water junction is placed into cooling bores 45A-45H and cooling fluid is injected directly into cooling bores 45A-45H through the water junction. The cooling fluid enters through an entrance at the water junction and empties through an exit inside the baffle. Cooling fluid enters and exits the interior of sprue block 38 and additional cross channels are optional. Cascade type cooling functions to cool down or otherwise control the temperature of sprue 26 and sprue block 38 in order to assist in regulating the temperature of molten metal flowing through sprue block 38, similar to regular baffle type cooling.
The cooling system of the present invention allows for simpler manufacturing and improved performance of cooling blocks. For example, since each block is comprised of a single piece, complete with cooling channels, no brazing is required to form a part with intricate cooling channels. Thus, the overall strength of each cooling block is increased and the risk of bursting a joint between joined parts is eliminated.
FIG. 3D shows a front view of spreader block 40 showing cooling channels 46A-46C in hidden lines. FIG. 3 E shows a sectional view of spreader block 40 taken along section 3-3 of FIG. 2 and showing cooling channels 46A-46C in hidden lines. FIGS. 3D and 3E are discussed concurrently. Spreader block 40 includes, sprue post 28, runner 30, outlet 32, spreader block cooling channels 46A-46C, spreader block mounting holes 64A-64D and baffle channel 66. Sprue post 28 is a conventional sprue post type and is used to direct molten metal into the runner system of die casting system 10.
Runner 30 is a small channel that is machined out of spreader block 40 that is positioned along runner portion 67 of spreader block 40 and allows material to flow to die cavity 16. Spreader block water channel 46A and baffle channel 54 are used to circulate cooling water through spreader block 40 in order to control heat transfer between sprue post 28 and the molten metal traveling through runner 30. Spreader block mounting holes 64A-64D are used to couple spreader block 40 to moving die half 14 with threaded fasteners, or in some such similar fashion. Mounting holes 46A-46D are typically placed in the corners of spreader block 40.
Runner portion 67 has a length I that allows runner 30 to extend from sprue post 28 to the runner system of a mold or die, such as runner 34. Runner 30 begins at the tip of sprue post 28 and terminates at outlet 32. Sprue post receives material from nozzle 24 through sprue 26, thus allowing material to flow directly from sprue post 28 into runner 34 of the die halves 12 and 14. No additional components or pieces are necessary to connect sprue block 38 and spreader block 40 with runner 34.
In order to keep spreader block 40 and the material at a desired temperature, sprue post 28 and runner 30 are temperature controlled using cooling channels 46A-46C, baffle channel 66 and baffle 68.
Cooling channel 46A is positioned so that it passes through spreader block 40 adjacent sprue post 28. Cooling channel 46A intersects baffle channel 66, which enters spreader block 40 on a face opposite the face on which sprue post 28 is located, and is positioned directly opposite of sprue post 28. Cooling fluid is passed through cooling channel 46A and baffle 68, similar to baffles 62A and 62B of sprue block 38, and deflects the cooling fluid into baffle channel 66 such that sprue post 28 can be temperature controlled. The cooling of spreader 28 also assists in dissipating heat from the injected material flowing through sprue 26 and thus assists in controlling temperatures and cycle times in system 10. Additionally, cooling channels 46B and 46C extend along runner portion 67 of spreader block 40 to assist in cooling runner 30. Runner portion 67 extends far enough to reach die halves 12 and 14 so that additional runner extensions are eliminated. In order to optimize temperature control in cooling block 18 along runner 30, additional cooling channels are required. However, the number and position of cooling channels included in block 40 varies depending on the size, number and positioning of runners fabricated into spreader block 40. Spreader block 40 may include additional runners extending from sprue post 28 to die halves 12 and 14. As such, additional cooling channels can be positioned along spreader block 40 to cool each additional runner.
In other embodiments of spreader block 40, cascade type cooling can be used similar to that which was described in conjunction with sprue block 38 in FIG. 3C. In which case, a cascade water junction is placed into baffle channel 66 and cooling channel 46A is not used and is sealed up at both ends or omitted from spreader block 40. Cooling fluid is directed into cooling channel 66 through the water junction and empties back through the baffle, whereby the cooling fluid cools down spreader post 28 in order to assists in regulating the temperature of material flowing through spreader block 40.
FIG. 4 shows a sectional view of assembled cooling blocks 18A and 18B taken along section 3-3 of FIG. 2. FIG. 5 shows a sectional view of assembled cooling blocks 18A and 18B taken along section 3-3 of FIG. 2. Cooling block 18A comprises sprue block 38, and cooling block 18B comprises spreader block 40. Spreader block 40 is coupled with sprue block 38 inside die casting system 10 such that sprue post 28 is concentrically located inside sprue 26. During operation of die casting system 10, bushing block 38 and spreader block 40 open and close along interface I. There is a small gap between sprue post 28 and sprue 26 of sprue bushing 42, which is not visible in FIGS. 3A-5. In one embodiment, the gap is approximately 0.030 inches. Additionally, there is also an approximately a 0.030 inch gap between sprue block 38 and spreader block 40. Runner 30 is machined into sprue post 28 and spreader block 40. Runner 30 is used to connect manufacturing material flowing from runner sprue 26 with die runner 34 of FIG. 1. The specific size, depth and location of runner 30 depends on the specific needs as dictated by the requirements of the die and die cavity. Additional runners can also be used. When closed, manufacturing material enters cooling blocks 18A and 18B through sprue 26 and then fills runner 30. The material exits cooling blocks 18A and 18B through outlet 32 and enters die runner 34 of die casting system 10. Spreader block 40 and sprue block 38 absorb heat from the molten metal flowing through sprue 26. This heat is then absorbed by cooling fluid circulating through cooling channels 44A-44G, cooling bores 45A-45H and cooling channels 46A-46C. The rate of heat transfer between cooling blocks 18A and 18B and the circulating cooling fluid is proportional to the product of the temperature difference and the exposed surface area of the cooling channels. As such the size of the cooling channels can be adjusted as needed for specific casting or molding systems. Injected material flowing out of cooling blocks 18A and 18B through outlet 32 can be set to an optimal temperature for flowing through die runner 34 and then rapidly cooling inside die cavity 16 by controlling the temperature of the cooling water. This accordingly reduces the time required for the injected metal to solidify in die cavity 16, which increases efficiency in the die casting system. After a die cast article is molded in die chamber 16, spreader block 40 is pulled away from sprue block 38 along interface I when movable die half 14 is pulled away from stationary die half 12. Ejectors 36 (shown in FIG. 1) remove the cast or molded article from die cavity 16 and hardened molten metal remaining in runner 30 and die runner 34.
The relative sizes of cooling blocks 18A and 18B shown in FIGS. 1-5 are exemplary only. Sprue block 38 and spreader block 40, including sprue 26, sprue post 28, and the collective cooling channels, can be made having various dimensions for use in smaller or larger die casting or injection molding operations. Smaller dimensioned cooling blocks 18 are suitable for a double mold systems, where two cooling blocks 18 are disposed next to each other in the die. This allows the cooling of two streams of metal to be injected into a mold, either simultaneously or sequentially. Larger runner cooling blocks can be used for dies requiring a higher throughput of molten metal.
Both sprue block 38 and spreader block 40 can be manufactured from materials with high thermal conductivities, such as tool steels, heat-treated steels, copper, beryllium and/or beryllium-free materials, and combinations thereof In one embodiment, sprue block 38 and spreader block 40 are made of heat treated AISI H-13 steel.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
Patent Application
20080041552
