DESC:FIELD OF INVENTION
This invention relates to a die design for pressure die casting process and more particularly it is related to multi cavity type die design for pressure die casting process.
CROSS REFERENCE TO RELATED INVENTION
This invention takes priority from an earlier filed provisional patent application no. 201921011388 filed on March 25, 2019; which is incorporated herein as reference.
BACKGROUND
A pressure die casting process is well-known process for manufacturing cast components of various metal for example aluminum alloy etc. Normally the dies are having single cavity for pressure die casting process. Many times two or more cavity dies are used to increase the productivity. In multi cavity type die design, part cavities are mostly placed in balance position with respect to metal flow and it’s time to travel from filler to runner gate. In multi cavity die, two different shaped cavities are placed in die. During metal travel in these concepts, metal flow may get disturbed, if runner gate flow balance (distance and time) is not maintained. And if hydraulic sliding cores are present in the die, it further worsens the situation and very difficult to achieve metal balance in runner-gate system. This produces casting flow defects and porosity. A US patent no 6499529 disclose multi cavity die ceramic rotating mold. Here a molten metal is filled in cavities by centrifugal force and is solidified while mold is rotating. This reduces shrinkage problem during solidification of metal. But the rotating mold has disadvantages like bulky, requires more infrastructure, and limitations to provide side cores.
Conventionally in any multi cavity die which has got sliding cores, cavities are placed in one parting plane, in such a way that, sliding core mechanism operation is given preference in die design over runner and gate balance. Hence metal flow is jeopardized causing casting defects mentioned above. Proving the die design with this concept is always a challenge and takes considerable time and efforts. And if proven, it needs very close control in pressure die casting parameters.

OBJECT OF THE INVENTION
The object of the present invention is to overcome the above mentioned worries and to design a multi cavity die for pressure die casting process which is fast, reliable and produce defect free die cast parts.
SUMMARY OF THE INVENTION
With this object in view, the present invention provides a multi cavity die (40, 60, 70) for pressure die casting process comprises; plurality of cavities (41, 42, 61, 62, 71, 72) each having its parting plane (Z1, Z2), at least a filler (45, 69, 79), each cavity has runner (47, 49, 63, 64, 73, 74) and runner gate (43, 44, 65, 66, 75, 76),
wherein; each cavity (41, 42, 61, 62, 71, 72) has at least one sliding core (51, 52, 53, 54, 77, 78) and wherein said parting plane (Z1, Z2) are located in different plane while maintaining substantially same metal flow rate for each cavity.
Preferably the said multi cavity die (60) comprises runners (63, 64) and gates (65, 66) for cavities (61, 62) respectively wherein; distance between filler (69) and gate (65) is not equal to distance between filler 69 and gate 66 and wherein; the shape and size of each runner (63, 64) is optimized to maintain substantially same metal flow rate for each cavity (61, 62).
Preferably the said multi cavity die (40) comprises runners (47, 49) and gates (43, 44) for cavities (41, 42) respectively wherein; distance between filler 45 and gate 43 is equal to distance between filler 45 and gate 44 to maintain substantially same metal flow rate for each cavity (41, 42).

Preferably the said multi cavity die (40, 60) wherein; the orientation of gates (43, 44, 65, 66) are so arranged to keep minimum restriction to flow of molten metal in the runners (47, 49, 63, 64).
Preferably the said multi cavity die (40, 60) wherein gates (43, 44, 65, 66) are so arranged to have minimum bends and no sharp bends in flow path (48, 50, 67, 68) of molten metal for cavities (41, 42, 61, 62).
Preferably the said multi cavity die (40, 60) wherein; at least two parting planes Z1 and Z2 are parallel to each other.
Preferably the said multi cavity die 40 comprise; a metal flow passages (47, 49) for cavities (41, 42) wherein;
at least two metal flow passages (47, 49) are of same shape and size.
Preferably the said multi cavity die (40, 60) comprise; sliding core (51, 52, 53, 54) for cavities (41, 42, 61, 62) respectively wherein;
cavities (41, 42, 61, 62) are not parallel to each other and at least two sliding core (51and 52 ; 53 and 54) are moving parallel to each other during operation.
Preferably the said multi cavity die (70) comprise; sliding core (77, 78) for cavities (71, 72) respectively wherein;
cavities (71, and 72) are parallel to each other and at least two sliding core (77 and 78) are not moving parallel to each other during operation.
Preferably the said multi cavity die (40, 60, 70) wherein; the pressure die casting process is of the type of high pressure die casting process.
DESCRIPTION OF DRAWINGS
Figure1 is a schematic view of single cavity die according to one of the prior art pressure die casting process;

Figure 2 is a schematic view of twin cavity die according to another prior art pressure die casting process;
Figure 3 is a schematic view of multi cavity die according to the present invention pressure die casting process;
Figure 4 is another schematic view of figure 3;
Figure 5 is a schematic top view of figure 3;
Figure 6 is a schematic side view of figure 3;
Figure 7 is a schematic view of multi cavity die according to another embodiment of the present invention pressure die casting process;
Figure 8 is schematic top view of figure 7;
Figure 9 is schematic side view of figure 7;
Figures 10a to 10d are schematic views of multi cavity die according to yet another embodiment of the present invention pressure die casting process.
DESCRIPTION OF THE INVENTION
A known single cavity die 10 as shown in figure 1 comprise a runner gate 11, slider 2, overflow/ air escape passages 13 and filler 14. A known twin cavity die 20 as shown in figure 2 comprise first cavity 26, second cavity 27, filler 28, runner gates 21, 22 and overflow/ air escape passages 25. Both the cavities 26 and 27 are in the same die 20 and place in one parting plane. Both the cavities 26 and 27 cannot be placed in the same or identical orientation with respect to location of filler 28 due to limitations posed due to accommodating side cores 23, 24 of side cores and overflow/ air escape passages 25. For example the overflow/ air escape passages 25 and side cores 23,24 of both the cavities may create hindrance to each other. A molten metal is pressurized through common filler 28 and flows to runner gate 21 of first cavity 26 through passage 29 as shown by a flow path 30. At the same time molten metal also flows to runner gate 22 of second cavity 27 through passage 31 as shown by a flow path 32. The metal flow passage 29 for first cavity 26 is different (in terms of shape, size and location with respect to filler 28) than the metal flow passage 31 of second cavity 27. Due to this the metal flow balance (in terms of distance and time) cannot be maintained for both the cavities. This produces flow defects in the casted parts. Also in this arrangement direction of side core 23 for first cavity 26 is different than direction of side core 24 for second cavity 27. Due to different directions, separate sliders (mechanical or hydraulic cylinders) are to be provided for each core. This will increase the cost and consume more space.
Now a preferred embodiment of the present invention is explained below referring to figures 3, 4, 5 & 6.
A multi cavity die 40 for pressure die casting process comprise a first cavity 41, a second cavity 42, runner gate 43 for first cavity 41, runner gate 44 for second cavity 42, filler or biscuit 45 for filling a molten metal in cavities 41, 42 through main runner 45a & runner gates 43, 44 and overflow/ air escape passages 46. Both the cavities 41 and 42 are in the same die 40 but placed in different parting plane. The parting plane Z1 of first cavity 41 is different than the parting plane Z2 of second cavity 42. The parting planes Z1 and Z2 are parallel to each other. Due to this both the cavities 41 and 42 can be placed in the same or identical orientation with respect to location of runner gates 43 and 44 respectively. A molten metal is pressurized through common filler 45 and flows to runner gate 43 of first cavity 41 through passage 47 as shown by a flow path 48. At the same time molten metal also flows to runner gate 44 of second cavity 42 through passage 49 as shown by a flow path 50. The metal flow passage or runner 47 for first cavity 41 is same or identical (in terms of shape and size) as the metal flow passage or runner 49 of second cavity 42. Both the runner gates 43 and 44 are at equal distance from filler 45. Due to this the metal flow balance (in terms of distance and time) can be maintained for both the cavities. This avoids flow defects in the casted parts. Also in this arrangement direction of sliding core 51 for first cavity 41 is same as direction of sliding core 52 for second cavity 42. Both the sliding cores 51 and 52 are moving parallel to each other. Due to this same direction, only one slider (mechanical or hydraulic cylinder) can be provided for both cores. This will reduce the cost and consume less space. Also due to providing the two cavities 41 and 42 in different planes, these cavities can be placed in the same or identical orientation with respect to filler 45 without any limitations to accommodate side cores 51, 52 of side cores and overflow/ air escape passages 46, for example the overflow/ air escape passages of both the cavities do not create hindrance to each other.
In another embodiment of the present invention, a multi cavity die 60 for pressure die casting process comprise at least two cavities 61, 62. Refer figures 7, 8 and 9. Gates (65, 66) are provided to each cavity (61. 62) for filling molten metal in the cavity through a common filler 69. Distance between filler 69 and gate 65 is not equal to distance between filler 69 and gate 66. Runners 63, 64 for the cavities 61, 62 may be of different shape and size. The shape and size of each runner 63, 64 is optimized to maintain substantially same metal flow rate for each cavity (61, 62), so that the molten metal reach to gates (65, 66) of cavities (61, 62) at the same instant.(For example length of runner (64) is 270mm which is more than length of runner (63) 245mm. Here due to more length of runner (64) the molten metal will reach to cavity (62) later than to cavity (61). Hence the shape and size of runner (64) is optimized by reducing its section area to 750 square mm as compared with section area of runner 63 is 880 square mm. Due to less section area, the flow of molten metal in runner 64 will increase and the molten metal will reach to cavity 62 fast and at the same instant that of cavity 61).
The orientation of gates (65, 66) is optimizes to keep minimum restriction to flow of molten metal in the runners (63, 64). The flow path (67, 68) of molten metal for cavities (61, 62) have minimum bends and no sharp bends so that the flow of molten metal in the runners (63, 64) is smooth and have minimum restrictions.
Further each cavity 61, 62 may have two or more sliding cores including bottom cores (53, 54) which are moving parallel to each other.
Referring to figure 10a, 10b, 10c and 10d, an another embodiment of the present invention, a multi cavity die 70 for pressure die casting process comprise at least two cavities 71, 72. Both the cavities 71 and 72 are in the same die 70 but may not parallel to each other. The parting plane Z1 of first cavity 71 is different than the parting plane Z2 of second cavity 72. The parting planes Z1 and Z2 are parallel to each other. Gates (75, 76) are provided to each cavity (71. 72) for filling molten metal in the cavity through a common filler 79 and runners (73, 74). In this arrangement, the orientation of both the cavities (71, 72) with respect to each other is so arranged that the runners (73, 74) of both cavities are symmetrical in shape, size and length. Both the runner gates 75 and 76 are at equal distance from filler 79. Due to this the metal flow balance (in terms of distance and time) can be maintained for both the cavities (71, 72). This avoids flow defects in the casted parts. Each cavity (71, 72) may have two or more sliding cores (77, 78) which may not moving parallel to each other.
In yet another embodiment of the present invention, the above multi cavity die casting process may be applied to gravity die casing method.
With the above process, the casting quality of each die will be same and consistent. A defect free casting can be produced with higher productivity with this process.
All variations and modifications obvious to the skilled persons are within the scope of the invention.
,CLAIMS:1. A multi cavity die (40, 60, 70) for pressure die casting process comprises; a plurality of cavities (41, 42, 61, 62, 71, 72) each having its parting plane (Z1, Z2), at least a filler (45, 69, 79), each cavity has runner (47, 49, 63, 64, 73, 74) and runner gate (43, 44, 65, 66, 75, 76),
wherein; each cavity (41, 42, 61, 62, 71, 72) has at least one sliding core (51, 52, 53, 54, 77, 78) and said parting plane (Z1, Z2) are located in different plane while maintaining substantially same metal flow rate for each cavity.

2. A multi cavity die (60) as claimed in claim 1, comprises runners (63, 64) and gates (65, 66) for cavities (61, 62) respectively wherein; distance between filler (69) and gate (65) is not equal to distance between filler 69 and gate 66 and shape and size of each runner (63, 64) is optimized to maintain substantially same metal flow rate for each cavity (61, 62).

3. A multi cavity die (40) as claimed in claim 1, comprises runners (47, 49) and gates (43, 44) for cavities (41, 42) respectively, wherein distance between filler 45 and gate 43 is equal to distance between filler 45 and gate 44 to maintain substantially same metal flow rate for each cavity (41, 42).

4. A multi cavity die (40, 60) as claimed in claim 2 and 3, wherein the orientation of gates (43, 44, 65, 66) are so arranged to keep minimum restriction to flow of molten metal in the runners (47, 49, 63, 64).

5. A multi cavity die (40, 60) as claimed in claim 4, wherein gates (43, 44, 65, 66) are so arranged to have minimum bends and no sharp bends in flow path (48, 50, 67, 68) of molten metal for cavities (41, 42, 61, 62).

6. A multi cavity die (40, 60) as claimed in claim 1, wherein at least two parting planes Z1 and Z2 are parallel to each other.

7. A multi cavity die 40 as claimed in claim 3, comprises a metal flow passages (47, 49) for cavities (41, 42), wherein
at least two metal flow passages (47, 49) are of same shape and size.

8. A multi cavity die (40, 60) as claimed in claim 1, comprises sliding core (51, 52, 53, 54) for cavities (41, 42, 61, 62) respectively, wherein
cavities (41 and 42 ; 61 and 62) are parallel to each other and at least two sliding core (51and 52 ; 53 and 54) are moving parallel to each other during operation.
9. A multi cavity die (70) as claimed in claim 1, comprises sliding core (77, 78) for cavities (71, 72) respectively, wherein
cavities (71, 72) are not parallel to each other and two sliding core (77, 78) are not moving parallel to each other during operation.
10. A multi cavity die (40, 60) as claimed in any of the above claims, wherein the pressure die casting process is of the type of high pressure die casting process.