DIE FOR DIE CASTING AND METHOD OF MANUFACTURING CAST PRODUCT

Abstract

According to one embodiment, a die includes a stationary die and a movable die. Between the stationary die and the movable die, a product section which includes a main product section, and a protrusion part protruding from the main product section toward a side of the biscuit section, a first runner configured to guide molten metal toward the main product section, and a second runner configured to guide molten metal toward the protrusion part are formed. The second runner is provided at a position deviated from the first runner three-dimensionally, and overpasses the first runner.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2008-050568, filed Feb. 29, 2008, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Field

One embodiment of the invention relates to a technique associated with die casting.

2. Description of the Related Art

A die-casting die of the cold-chamber die casting system comprises a biscuit section for receiving molten metal from an injection apparatus of a casting machine, a product section that is a space in which a product is to be cast, a main runner for guiding molten metal from the biscuit section toward the product section, and a main gate provided between the main runner and the product section, for accelerating the flow speed of the molten metal by sharply reducing the thickness.

Here, the solidification time of molten metal of, for example, a magnesium alloy or the like is very short, and hence in a die-casting die having a small flow cross-sectional area (i.e., a cross-sectional area of a space through which molten metal flows), the product section is not filled with the molten metal up to every corner thereof, and deficient filling occurs in some cases. For this reason, some of the die-casting dies liable to suffer deficient filling are provided with a sub-runner and a sub-gate for performing flow-rate support from the lateral side of the product section in addition to the main runner and the main gate.

In Jpn. Pat. Appln. KOKAI Publication No. 2002-45956, a die structure provided with a sub-runner branching off from a main runner is disclosed. The sub-runner extends to the side of the product section, and communicates with the side-edge part of the product section.

In Jpn. Pat. Appln. KOKAI Publication No. 2002-263820, a die for casting a display cover is disclosed This display cover has a support wall formed by injecting a magnesium alloy into a space of a die. This support wall includes a lower edge section and an upper edge section located on the opposite side of the lower edge section. At a central part of the lower edge section, a cutout part cut out to face the upper edge section is provided. The gate of the die is connected to the cutout part.

Incidentally, for example, in a cast product such as the display cover described in the Jpn. Pat. Appln. KOKAI Publication No. 2002-263820, a protrusion section is present at the edge part thereof. A product section of a die for casting such a cast product includes a main product section in which a main part of the cast product situated off the protrusion section is to be cast, and a protrusion part which protrudes from the product section, and in which the protrusion section is to be cast. Further, the protrusion part is arranged on the biscuit section side of the main product section in some cases.

In such a die, when the main gate is connected to the main product section, the protrusion part is positioned on the upstream side of the molten metal filling port of the main gate with respect to the molten metal flow. Molten metal of a magnesium alloy or the like becomes a flow having high directivity because of the inertia, and hence the protrusion part is hardly filled with molten metal. For this reason, there is the possibility of defective casting such as deficient strength or the like being caused at the protrusion part.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.

FIG. 1 is an exemplary exploded perspective view of a die according to one embodiment of the present invention;

FIG. 2 is an exemplary perspective view of a cast product according to the embodiment of the present invention;

FIG. 3 is an exemplary view schematically showing the structure of an internal space of the die shown in FIG. 1;

FIG. 4 is an exemplary perspective view showing a region of the structure of the internal space of the die shown in FIG. 3 encircled by a line F4 in an enlarging manner;

FIG. 5 is an exemplary view showing an example of a structure of an internal space of a die;

FIG. 6 is an exemplary view showing another example of a structure of an internal space of a die; and

FIG. 7 is an exemplary view showing a further example of a structure of an internal space of a die.

DETAILED DESCRIPTION

Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, a die for die casting comprises: a stationary die; and a movable die to be combined with the stationary die. When the movable die is combined with the stationary die, a biscuit section, a product section, a first runner, a first gate, a second runner, and a second gate are formed between the stationary die and the movable die. The biscuit section is a section into which molten metal is to be injected. The product section comprises a main product section, and a protrusion part which protrudes from the main product section toward a side of the biscuit section. The first runner is configured to guide the molten metal injected into the biscuit section toward the main product section. The first gate is provided between the first runner and the main product section at a position on a downstream side of the protrusion part in a stream direction of the molten metal. The second runner is configured to guide the molten metal injected into the biscuit section toward the protrusion part. The second gate is provided between the second runner and the protrusion part. The second runner is provided at a position deviated from the first runner three-dimensionally, and overpasses the first runner.

According to one embodiment of the invention, a method of manufacturing a cast product by die casting according to the present invention comprises: preparing a die which comprises a stationary die, and a movable die to be combined with the stationary die, and in which when the movable die is combined with the stationary die, a biscuit section, a product section, a first runner, a first gate, a second runner, and a second gate are formed between the stationary die and the movable die, (i) the biscuit section being a section into which molten metal is to be injected, (ii) the product section comprising a main product section, and a protrusion part which protrudes from the main product section toward a side of the biscuit section, (iii) the first runner configured to guide the molten metal injected into the biscuit section toward the main product section, (iv) the first gate being provided between the first runner and the main product section at a position on a downstream side of the protrusion part in a stream direction of the molten metal, (v) the second runner configured to guide the molten metal injected into the biscuit section toward the protrusion part, (vi) the second gate being provided between the second runner and the protrusion part, and (vii) the second runner being provided at a position deviated from the first runner three-dimensionally and overpassing the first runner; combining the movable die with the stationary die; and injecting molten metal into the biscuit section.

A die 1, and a method of manufacturing a cast product 2 according to one embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 shows a die 1 according to this embodiment.

The die 1 is used for die casting of, for example, the cold-chamber die casting system. For example, a magnesium alloy, aluminum alloy, or zinc ally is injected into this die 1 as molten metal by pressure. Incidentally, the die according to the present invention is not limited to the above materials, and can be widely used for die casting in which various materials are used as molten metal.

FIG. 2 shows an example of a cast product 2 which is a product cast by using the die 1. The cast product 2 is, for example, a component constituting a part of a main body housing of an electronic apparatus such as a portable computer, or a part of a housing of a display unit of an electronic apparatus. A housing base constituting a bottom part of an apparatus body, a display cover for protecting a back surface of a display apparatus, and the like correspond to the more detailed specific examples. Incidentally, cast products to which the present invention can be applied are not limited to the above examples, and various other products may be produced.

As shown in FIG. 2, the cast product 2 comprises, for example, a rectangular bottom wall 11, and a vertical wall 12 rising from a peripheral edge part of the bottom wall 11, thereby having a box-like shape opened on one side thereof. The cast product 2 further comprises a first end part 13, a second end part 14 positioned on the opposite side of the first end part 13 in the cast product 2, and side edge sections 15 and 16 each extending between first and second end parts 13 and 14. The first and second end parts 13 and 14 extend in, for example, the longitudinal direction of the cast product 2. A cutout part 17 cut out toward the second end part 14 is provided at a central part of the first end part 13.

This cutout part 17 is provided to form, for example, a power supply unit insertion section to which, for example, a battery is detachably attached, or a display unit foot section to which hinges are attached. Incidentally, the purposes of providing the cutout part 17 are not limited to the above examples, and a cutout part provided for various uses corresponds to the cutout part mentioned in the present invention.

As shown in FIG. 2, the cast product 2 comprises the cutout part 17, and thus comprises a pair of protrusion sections 22a and 22b protruding from corner parts defined by the first end part 13, and the side edge sections 15 and 16 toward the opposite side of the second end part 14. That is, the cast product 2 comprises a main part 21, and the protrusion sections 22a and 22b. The main part 21 is the remaining part of the cast product 2 excluding the protrusion sections 22a and 22b.

The protrusion sections 22a and 22b are provided separately from each other at both end parts of, for example, the first end part 13 in the longitudinal direction. The cutout part 17 is provided relatively large to occupy a large part of, for example, the first end part 13, and is formed larger than, for example, the total of the protrusion sections 22a and 22b. An example of the cast product 2 is a thin-walled product having a fundamental thickness of, for example, 0.6 mm or less. Incidentally, “fundamental thickness” implies a standard thickness of the product, and a thickness which is adopted most widely throughout the product. Incidentally, the die according to the present invention may also be used for casting exceeding 0.6 mm in the fundamental thickness.

As shown in FIG. 1, the die 1 comprises a stationary die 31, and a movable die 32 to be combined with the stationary die 31. The stationary die 31 is fixed to a stationary platen not shown. The stationary die 31 comprises a stationary die plate 33, a cavity member 34, and an inlet member 35.

The stationary die plate 33 is fixed to the stationary platen, and comprises a recess part (not shown) on a surface opposed to the movable die 32. The cavity member 34 is attached to the recess part, and is opposed to the movable die 32. The cavity member 34 comprises a die surface for forming, for example, an outer surface of the cast product 2. The inlet member 35 comprises a through-hole into which an injection plunger of the casting machine is inserted, and is a cylindrical shape.

On the other hand, the movable die 32 comprises a movable die plate 36, a core member 37, and a dividing piece 38. The movable die 32 is fixed to a movable platen (not shown), and is to be advanced and retreated between a die closed position in which the movable die is combined with the stationary die 31, and a die opened position in which the movable 32 is separated from the stationary die 31.

The movable die plate 36 is fixed to the movable platen, and comprises a recess part 36a on a surface opposed to the stationary die 31. The core member 37 is attached to the recess part 36a, and is opposed to the stationary die 31. The core member 37 comprises a die surface for forming, for example, an inner surface of the cast product 2.

When the movable die 32 is combined with the stationary die 31 as shown in FIG. 3, an internal space 41 into which molten metal is pressed is formed between the stationary die 31 and the movable die 32. FIG. 3 is a view obtained by viewing the internal space 41 as a plane for convenience of explanation. In FIG. 3, molten metal flows from above to below in the figure. Incidentally, in this description, when the term “upstream side” is simply used, it implies the upstream side with respect to the molten metal mainstream flow, and when the term “downstream side” is simply used, it implies the downstream side with respect to the molten metal mainstream flow. Here, the molten metal mainstream implies the molten metal flowing through the main gate, to be described later.

As shown in FIG. 3, the internal space 41 in the die 1 comprises a biscuit section 42, a product section 43, a fan gate 44, a first side gate 45a, 45b, a second side gate 46a, 46b, an overflow section 47, and a chillvent section 48. To be more specific, the fan gate 44 comprises a main runner 51, and a main gate 52. Each of the first side gate 45a, 45b comprises a first sub-runner 53, and a first sub-gate 54. Each of the second side gate 46a, 46b comprises a second sub-runner 55, and a second sub-gate 56.

The biscuit section 42 is formed inside the inlet member 35, and is a part which receives the high temperature molten metal from the injection apparatus of the casting machine at a high speed. That is, the biscuit section 42 is a section in to which molten metal is to be injected. The product section 43 is an internal space in which the cast product 2 is to be cast, and comprises a dug-down surface corresponding to the shape of the cast product 2. As shown in FIG. 3, the product section 43 comprises first to fourth edge sections 61, 62, 63, and 64 corresponding to the four sides of the cast product 2.

The first edge section 61 is an example of the main edge section mentioned in the present invention. The first edge section 61 is located the most upstream in the product section 43, and corresponds to the first end part 13 of the cast product 2. The first edge section 61 is connected to the main gate 52. The second edge section 62 is located the most downstream in the product section 43, and corresponds to the second end part 14 of the cast product 2. The third and fourth edge sections 63 and 64 are each examples of the side edge section mentioned in the present invention. The third and fourth edge sections 63 and 64 extend from the end part of the first edge section 61 in the stream direction of the molten metal (i.e., the stream direction of the molten metal mainstream), and correspond to the side edge sections 15 and 16 of the cast product 2.

As shown in FIG. 3, the product section 43 comprises a main product section 66, and a pair of protrusion parts 67a and 67b. The main product section 66 is a space in which the main part 21 of the cast product 2 is to be cast. The protrusion parts 67a and 67b protrude from the main product section 66 toward the side of the biscuit section 42, and are spaces in which the protrusion sections 22a and 22b of the cast product 2 are to be cast.

The first edge section 61 of the product section 43 is cut out toward the second edge section 62. As a result of this, the corner sections defined by the first edge section 61, and the third and fourth edge sections 63 and 64 comprise a pair of protrusion parts 67a and 67b protruding toward the opposite side (i.e., the upstream side) of the second edge section 62. As shown in FIG. 3, the protrusion parts 67a and 67b are arranged on the biscuit section 42 side (i.e., on the upstream side) of the main product section 66.

The paired protrusion parts 67a and 67b are formed separately from each other at both end parts of, for example, the first edge section 61. The first edge section 61 comprises a first section 61a, which is a central part situated off the protrusion parts 67a and 67b, and second sections 61b and 61c in which the protrusion parts 67a and 67b are provided, respectively.

As shown in FIG. 3, the fan gate 44 is a flow path for guiding the mainstream of the molten metal to the product section 43. The fan gate 44 comprises, as described above, the main runner 51, and the main gate 52. The main runner 51 is continuous with the biscuit section 42, and is configured to guide the molten metal injected into the biscuit section 42 from biscuit section 42 toward the first section 61a (i.e., the main product section 66) of the first edge section 61 of the product section 43. The main runner 51 comprises an upstream section 51a connected to the biscuit section 42, and a downstream section 51b connected to the main gate 52. The downstream section 51b of the main runner 51 is largely widened as compared with the upstream section 51a such that the molten metal is to be guided toward substantially the entire part of the first section 61a of the first edge section 61.

As shown in FIG. 3, the main gate 52 is provided between the main runner 51 and the first section 61a of the first edge section 61 of the product section 43. The thickness of the main gate 52 is made smaller than that of the main runner 51. The thickness of the main gate 52 is sharply reduced at a position thereof closer to the product section 43, whereby the flow of the molten metal is accelerated toward the product section 43. The main gate 52 has, for example, a thickness substantially equal to the fundamental thickness (for example, 0.6 mm) of the cast product 2 at the minimum cross-sectional part of the main gate 52. The main gate 52 is provided on the extension of, for example, the part in which the bottom wall 11 of the cast product 2 is to be formed.

The border between the main gate 52 and the first section 61a of the first edge section 61 of the product section 43 becomes a filling port 71 of the molten metal mainstream for the product section 43. That is, the main gate 52 communicates with the product section 43 at a position on the downstream side of the protrusion parts 67a and 67b.

As shown in FIG. 3, the first side gate 45a, 45b is an auxiliary flow path for performing flow-rate support for the product section 43. Each of the first side gates 45a, 45b comprises, as described above, the first sub-runner 53, and the first sub-gate 54. The first sub-runner 53 is an example of the first runner mentioned in the present invention. The first sub-gate 54 is an example of the first gate mentioned in the present invention. Incidentally, the first side gate 45a, 45b may be provided only on one side, i.e., on one of the right and left sides depending on the shape of the product.

As shown in FIG. 3, the first sub-runners 53 branch off from both sides of the main runner 51, and pass around the product section 43, and extend on both sides of the product section 43 along the third and fourth edge sections 63 and 64. The first sub-runner 53 is configured to guide the molten metal injected into the biscuit section 42 toward the third and fourth edge sections 63 and 64 of the main product section 66.

The first sub-gates 54 are provided between the first sub-runners 53 and the third and fourth edge sections 63 and 64 (i.e., the main product section 66) of the product section 43, and supply the molten metal to the main product section 66 from the sides. The thickness of the first sub-gate 54 is made smaller than that of the first sub-runner 53.

To be more specific, the first sub-gates 54 are connected to, for example, the third and fourth edge sections 63 and 64 at the end parts on the filling end side of the product section 43. The boundary between each of the first sub-gates 54 and each of the third and fourth edge sections 63 and 64 becomes the filling port 72 of the molten metal for the product section 43. That is, the first sub-gate 54 communicates with the product section 43 at a position on the downstream side of the protrusion part 67a, 67b in the stream direction of the molten metal.

As shown in FIG. 3, the second side gate 46a, 46b is an auxiliary flow path for performing flow-rate support for the protrusion part 67a, 67b of the product section 43. Each of the second side gate 46a, 46b comprises, as described above, the second sub-runner 55, and the second sub-gate 56. The second sub-runner 55 is an example of the second runner mentioned in the present invention. The second sub-gate 56 is an example of the second gate mentioned in the present invention.

The second sub-runners 55 branch off from both sides of the main runner 51 at positions on the upstream side of the first sub-runners 53 in the stream direction of the molten metal, and extend toward the protrusion parts 67a and 67b of the product section 43. The second sub-runner 55 is configured to guide the molten metal injected into the biscuit section 42 toward the protrusion part 67a, 67b of the product section 43.

FIG. 4 shows the sub-runner 55 of the one second side gate 45a in detail. Incidentally, the other second side gate 45b also has substantially the same configuration. As shown in FIG. 4, the second sub-runner 55 comprises a first section 81, a second section 82, and a third section 83. The first section 81 branches off from the main runner 51, and extends in parallel with, for example, the first sub-runner 53.

Here, as shown in FIG. 4, the first sub-runner 53 is provided at a position deviated from the main gate 52 three-dimensionally. Incidentally, the expression “deviated three-dimensionally” implies deviation in the thickness direction of the die 1. The first section 81 of the second sub-runner 55 is provided on the same plane as the first sub-runner 53.

The second section 82 of the second sub-runner 55 is provided on the downstream side of the first section 81. The second section 82 is provided at a position deviated from the first section 81 three-dimensionally. The second section 82 extends perpendicularly to, for example, the first section 81, and crosses the first sub-runner 53.

This second section 82 is provided at a position deviated from the first sub-runner 53 three-dimensionally in order to avoid the first sub-runner 53, and hence the second section 82 overpasses the first sub-runner 53. To be more specific, the first sub-runner 53 is engraved in, for example, the core member 37 of the movable die 32. The second sub-runner 55 is engraved in, for example, the cavity member 34 of the stationary die 31. That is, the first and second sub-runners 53 and 55 extend in directions different from each other with the parting line of the die 1 as a boundary between the first and second sub-runners 53 and 55. The parting line is the boundary surface between the stationary die 31 and movable die 32. The first and second sub-runners 53 and 55 are in contact with each other at the crossing part.

The first section 81 comprises an extension section 81a extending from a part at which the second section 82 branches off from the first section 81. This extension section 81a functions as a shock absorption for absorbing the shock of the molten metal flow. The third section 83 extends in a direction perpendicular to, for example, the second section 82.

As shown in FIG. 3, the second sub-gate 56 is provided between the second sub-runner 55 and the protrusion part 67a, 67b of the product section 43, and directly supplies molten metal to the protrusion part 67a, 67b. The thickness of the second sub-gate 56 is made smaller than that of the second sub-runner 55.

As shown in FIG. 3, the overflow section 47 and the chillvent section 48 are provided on the downstream side of the product section 43. The overflow section 47 is a section for receiving air inside the product section 43 pushed out by the molten metal. The overflow section 47 is a section for reducing the filling resistance of the molten metal in the product section 43, and pushing out deteriorated molten metal at a flow tip to the outside of the product section 43. The chillvent section 48 is a section having a function of preventing the deteriorated molten metal from running out of the die 1.

Next, an example of a method of manufacturing the cast product 2 using the die 1 will be described below.

First, the die 1 described above is prepared, and the die 1 is set on the casting machine. Further, a raw material (for example, a magnesium alloy) is melted to obtain molten metal. Subsequently, the casting cycle is started. First, the movable die 32 is moved to be combined with the stationary die 31, and then the die 1 is clamped. Then, the molten metal is poured into a sleeve coupled to the inlet member 35, the injection plunger is forced out at a high speed, and the molten metal is injected into the biscuit section 42 of the die 1.

When the solidification of the cast product 2 is advanced to a certain degree, the movable die 32 moves to open the die 1, and the cast product 2 is taken out of the die 1 by ejecting pins. As a result of this, one cycle of the die casting is completed. The cast product 2 taken out of the die 1 is subjected to removal processing of a surplus part, thereby obtaining a cast product 2 having the desired shape.

Next, the function of the die 1 will be described below.

The molten metal forced into the biscuit section 42 is first filled into the main runner 51 having a relatively large flow cross-sectional area. Then, the molten metal flows into the first and second sub-runners 53 and 54 also having a relatively large flow cross-sectional area. The molten metal flowing through the main runner 51 is filled into the main product section 66 of the product section 43 through the main gate 52 directly connected to the main runner 51. Further, the molten metal flowing through the second sub-runners 55 is filled into the protrusion parts 67a and 67b of the product section 43 through the second sub-gates 56. Further, the molten metal flowing through the first sub-runners 53 is filled from the third and fourth edge sections 63 and 64 of the product section 43 through the first sub-gates 54.

At this time, the second sub-runner 55 overpasses the first sub-runner 53, and hence the molten metal flowing through the second sub-runner 55 hardly interferes with the molten metal flowing through the first sub-runner 53. That is, the molten metal flowing through the second sub-runner 55 is filled into the protrusion parts 67a and 67b of the product section 43 without causing much pressure loss.

According to the die 1 configured as described above, and the method of manufacturing the cast product 2, it is possible to reduce defective casting. FIG. 5 shows a die 91 which is not provided with a second sub-runner 55 and a second sub-gate 56. Here, the flow of molten metal of a magnesium alloy or the like has a high directivity because of the inertia. For this reason, when the die 91 described above is used, the upstream side corner parts 92 (hatched parts in FIG. 5) of the product section 43 comprising the protrusion parts 67a and 67b are not sufficiently filled with molten metal in many cases. That is, there is the possibility of the upstream side corner parts 92 being brought into a rough/fine filled state, causing defective casting problems such as deficient strength.

FIG. 6 shows a die 91 in which a second sub-gate 56 is provided in a middle part of the sub-runner 53 for performing flow-rate support for the main product section 66. Even when the die 91 described above is used, the molten metal has high directivity, and hence the molten metal flowing through the first sub-runner 53 passes through the entrance 93 of the second sub-gate 56 having a small flow cross-sectional area, and flows toward the distal end of the first sub-runner 53. For this reason, there is the possibility of the filling of the molten metal from the second sub-gate 56 into the protrusion part 67a, 67b being not sufficient, and the deficient filling being not solved. Further, it is after the completion of filling of the first sub-runner 53 having a relatively large flow cross-sectional area that the molten metal flows into the protrusion parts 67a and 67b through the second sub-gate 56, and hence the filling start timing of the filling from the second sub-gate 56 is delayed compared with the filling start timing of the filling from the main gate 52. For this reason, air is liable to be left inside the product section 43, thus there is the possibility of the defective casting being caused by gas inclusion and the like.

FIG. 7 shows a die 91 provided with a second sub-runner 55 and a second sub-gate 56. As shown in FIG. 7, the first and second sub-runners 53 and 55 are provided on the same plane, and intersect each other on the same plane. When such a die 91 is used, the molten metal flowing through the first sub-runner 53, and the molten metal flowing through the second sub-runner 55 interfere with each other at the intersection of the sub-runners 53 and 55, thereby causing a pressure loss. Thus, there is the possibility of the molten metal being not sufficiently supplied to the protrusion parts 67a and 67b from the second sub-gates 56. Further, there is also the possibility of gas inclusion or turbulent flow caused by the interference inducing a casting defect such as a molten metal wrinkle and the like.

On the other hand, as in the die 1 according to this embodiment, when the second runner 55 for guiding molten metal to the protrusion part 67a, 67b is provided separately from the first runner 53 for guiding molten metal to the main product section 56, and this second runner 55 overpasses the first runner 53 three-dimensionally, the molten metal flowing through the second runner 55 hardly interfere with the molten metal flowing through the first runner 53, and pressure loss is hardly caused. Accordingly, it is possible to supply sufficient molten metal to the protrusion part 67a, 67b into which molten metal cannot be easily filled, and prevent defective casting from occurring due to deficient filling. Further, if the molten metal flowing through the second runner 55 and the molten metal flowing through the first runner 53 hardly interfere with each other, it is possible to prevent defective casting such as a molten metal wrinkle and the like incidental to the interference from occurring.

In the case where the second sub-runner 55 for guiding molten metal to the protrusion part 67a, 57b is provided separately from the first sub-runner 53 for guiding molten metal to the main product section 66, it is possible to start filling from the second sub-gate 56 without waiting for the filling of the first sub-runner 53. That is, it is even possible to make the filling start timing at which filling is started from the second sub-gate 56 earlier than the die 91 shown in FIG. 6, and thus it becomes possible to perform filling in such a manner that air is hardly left inside the product section 43.

In the case where the first and second sub-runners 53 and 55 extend in directions different from each other with the parting line of the die 1 as the boundary, it is possible to realize a cubic interchange of the two runners with relative ease without providing a relative complicated shape on the die surface of the die 1.

In the case where the second sub-runner 55 branches off from the main runner 51 at a position on the upstream side of the first sub-runner 53, it becomes easier to supply molten metal sufficiently to the first sub-runner 53 requiring more molten metal than the second sub-runner 55. This contributes to reduction in defective casting.

The die 1 and the casting method of the cast product 2 according to one embodiment have been described above. However, the present invention is not limited to the above embodiment. At the implementation stage of the present invention, the constituent elements may be modified and embodied within the scope not deviating from the gist of the invention.

Although in the above embodiment two second side gates are provided, one side gate may be used, depending on the product shape. Incidentally, in the above embodiment, the first sub-runner is the first runner mentioned in the present invention, and the first sub-gate is the first gate mentioned in the present invention. However, instead, the main runner may be the first runner of the present invention, and the main gate may be the first gate of the present invention. In this case, the second runner overpasses the main runner three-dimensionally.

While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

Claims

1. A die for die casting comprising:

a stationary die; and

a movable die to be combined with the stationary die, wherein

when the movable die is combined with the stationary die, a biscuit section, a product section, a first runner, a first gate, a second runner, and a second gate are formed between the stationary die and the movable die,

the biscuit section being a section into which molten metal is to be injected,

the product section comprising a main product section, and a protrusion part which protrudes from the main product section toward a side of the biscuit section,

the first runner configured to guide the molten metal injected into the biscuit section toward the main product section,

the first gate being provided between the first runner and the main product section at a position on a downstream side of the protrusion part in a stream direction of the molten metal,

the second runner configured to guide the molten metal injected into the biscuit section toward the protrusion part, and

the second gate being provided between the second runner and the protrusion part, and

the second runner is provided at a position deviated from the first runner three-dimensionally, and overpasses the first runner.

2. The die according of claim 1, wherein

a main runner and a main gate are formed between the stationary die and the movable die,

the main runner configured to guide the molten metal from the biscuit section toward the main product section, and

the main gate being provided between the main runner and the main product section,

the product section comprises a main edge section connected to the main gate, and a side edge section extending from an end part of the main edge section in the stream direction of the molten metal,

the first runner is a first sub-runner branching off from the main runner, extending along the side edge section of the product section, and configured to guide the molten metal toward the side edge section, and

the second runner is a second sub-runner branching off from the main runner, and configured to guide the molten metal toward the protrusion part of the product section.

3. The die according of claim 2, wherein

the first runner and the second runner extend in directions different from each other with a parting line of the die as a boundary.

4. The die according of claim 3, wherein

the second runner branches off from the main runner at a position on an upstream side of the first runner in the stream direction of the molten metal.

5. A method of manufacturing a cast product by die casting, comprising:

preparing a die which comprises a stationary die, and a movable die to be combined with the stationary die, and in which when the movable die is combined with the stationary die, a biscuit section, a product section, a first runner, a first gate, a second runner, and a second gate are formed between the stationary die and the movable die, (i) the biscuit section being a section into which molten metal is to be injected, (ii) the product section comprising a main product section, and a protrusion part which protrudes from the main product section toward a side of the biscuit section, (iii) the first runner configured to guide the molten metal injected into the biscuit section toward the main product section, (iv) the first gate being provided between the first runner and the main product section at a position on a downstream side of the protrusion part in a stream direction of the molten metal, (v) the second runner configured to guide the molten metal injected into the biscuit section toward the protrusion part, (vi) the second gate being provided between the second runner and the protrusion part, and (vii) the second runner being provided at a position deviated from the first runner three-dimensionally and overpassing the first runner;

combining the movable die with the stationary die; and

injecting molten metal into the biscuit section.