INSTALLATION STRUCTURE FOR DIE CASTING SLEEVE, AND DIE CASTING SLEEVE

Abstract

A die casting sleeve, supported horizontally on a die casting device such that a cylinder portion front end communicates with a cavity and a plunger tip is inserted from a cylinder portion rear end, is configured such that the cylinder portion has a double structure in which an inner cylinder is fitted into an outer cylinder, the inner cylinder is made of a composite material of titanium or a titanium alloy and ceramic in at least a molten metal receiving region under an inlet port, a first planar portion is formed on the outer cylinder in the molten metal receiving region, and a cooling device including a tubular portion for letting a cooling medium flow in a jacket main body as a metal block having a second planar portion is mounted on the outer cylinder in a state where the second planar portion abuts against the first planar portion.

Claims

1. An installation structure for a die casting sleeve in which the die casting sleeve including a cylinder portion having a cylindrical shape and an inlet port penetrating through a part of a side peripheral wall of the cylinder portion is supported on a die casting device such that a cylinder portion front end communicates with a cavity and a plunger tip is inserted from a cylinder portion rear end in a state where a center axis of the cylinder portion is substantially horizontal and the inlet port is opened upward, wherein the cylinder portion has an outer cylinder and an inner cylinder fitted into the outer cylinder, the inner cylinder is formed by a sintered body made of a composite material of titanium or a titanium alloy and ceramic in at least a molten metal receiving region as a portion for receiving molten metal supplied through the inlet port in the cylinder portion, a first planar portion is formed on the outer cylinder in the molten metal receiving region, and a cooling device including a tubular portion for letting a cooling medium flow in a jacket main body as a metal block having a second planar portion is mounted on the outer cylinder in a state where the second planar portion directly abuts against the first planar portion or a state where the second planar portion indirectly abuts against the first planar portion with either of a graphite sheet or a metal foil interposed.

2. The installation structure for the die casting sleeve according to claim 1, wherein the cooling device is mounted on the outer cylinder in a state where the graphite sheet is interposed between the second planar portion and the first planar portion.

3. The installation structure for the die casting sleeve according to claim 1, wherein the cooling device is provided at a position deviating to one side such that an angle formed by a line connecting a center line of the cooling device and the center axis of the cylinder portion and a vertical line from a center of the inlet port is 10 degrees to 60 degrees to an opposite side to a ladle for supplying the molten metal to the inlet port on a cross section orthogonal to the center axis of the cylinder portion.

4. A die casting sleeve including a cylinder portion having a cylindrical shape and an inlet port penetrating through a part of a side peripheral wall of the cylinder portion, wherein the cylinder portion has an outer cylinder and an inner cylinder fitted into the outer cylinder, the inner cylinder is formed by a sintered body made of a composite material of titanium or a titanium alloy and ceramic in at least a molten metal receiving region including a portion facing the inlet port in the cylinder portion, a first planar portion is formed on the outer cylinder in the molten metal receiving region, and a cooling device including a tubular portion for letting a cooling medium flow in a jacket main body as a metal block having a second planar portion is mounted on the outer cylinder in a state where the second planar portion directly abuts against the first planar portion or a state where the second planar portion indirectly abuts against the first planar portion with either of a graphite sheet or a metal foil interposed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1A is a cross-sectional view when a sleeve as an embodiment of the present invention is cut at the center in the direction of a center axis, FIG. 1B is a bottom view of the sleeve, FIG. 1C is a cross-sectional view of the sleeve when cut along line A-A, and FIG. 1D is a perspective view of the sleeve when viewed from the bottom surface side.

[0039] FIG. 2A and FIG. 2B are views for explaining manufacturing of the sleeve in FIG. 1A to 1D.

[0040] FIG. 3 is a configuration view illustrating a main part of a general die casting device.

[0041] FIG. 4 is a view schematically illustrating supply of molten metal to a sleeve from a ladle in the general die casting device.

[0042] FIG. 5A is a perspective view of a cooling jacket that is compared with the present invention, and FIG. 5B is a cross-sectional view in a state where the cooling jacket in FIG. 5A is mounted on a conventional sleeve.

DESCRIPTION OF THE EMBODIMENTS

[0043] Hereinafter, a specific embodiment of the present invention will be described with reference to the drawings. A sleeve S1 includes a cylinder portion 1 having a cylindrical shape and an inlet port 30 penetrating through a part of a side peripheral wall of the cylinder portion 1. As illustrated in FIG. 3, the sleeve S1 is supported in a cold chamber die casting device DM in a state where a center axis X of the cylinder portion 1 is substantially horizontal and the inlet port 30 is opened upward. A cylinder portion front end El of the sleeve S1 communicates with a cavity 110 formed between a fixed mold 111 and a movable mold 112, and a plunger tip 70 is inserted from a cylinder portion rear end E2. Molten metal stored in a holding furnace is supplied to the inlet port 30 through a ladle 130.

[0044] As illustrated in Fig. lA to FIG. 1D, the cylinder portion 1 of the sleeve S1 has an outer cylinder 20 and an inner cylinder 10 fitted into the outer cylinder 20. A molten metal receiving region is a region for receiving the molten metal supplied through the inlet port 30. The inner cylinder 10 is made of a TC composite material (sintered body made of a composite material of titanium or a titanium alloy and ceramic) in at least the molten metal receiving region. In the embodiment, the whole inner cylinder 10 including the molten metal receiving region is made of the TC composite material. The TC composite material is manufactured by powder metallurgy and can be provided by sintering, under a non-oxidizing atmosphere, a molded green body molded using a raw material obtained by mixing titanium powder and silicon carbide powder. The raw material of the TC composite material can contain powder of another metal such as nickel.

[0045] The molten metal receiving region is a region that is increased in temperature when the molten metal is supplied through the inlet port 30. As illustrated in FIG. 1A, the molten metal receiving region in the direction parallel with the center axis X can be a range L from the cylinder portion rear end E2 to the length of twice the diameter of the inlet port 30. As illustrated in FIG. 10, the molten metal receiving region on the cross section orthogonal to the center axis X can be a range R1 indicated by a circular arc having a center angle a of 60 degrees to each of both sides from a vertical line Z from the center of the inlet port 30.

[0046] As illustrated in FIG. 2A and FIG. 2B, the outer cylinder 20 has a planar portion 20s formed in the molten metal receiving region, and a cooling device 40 is mounted on the planar portion 20s. The cooling device 40 is configured by providing a tubular portion 45 for letting a cooling medium flow in a jacket main body 41 as a metal block such as copper and aluminum having high heat conductivity. The jacket main body 41 has a flat substantially rectangular parallelepiped shape, and one of a pair of planar portions 41a having the largest areas abuts against the planar portion 20s of the outer cylinder 20. The tubular portion 45 has a substantially U shape, and both ends thereof respectively reach a pair of side surface portions 41b perpendicular to the pair of planar portions 41a to form openings 46. The cooling medium supplied through one of the openings 46 flows through the inside of the tubular portion 45 and is discharged through the other of the openings 46. With heat exchange of the cooling medium flowing through the inside of the tubular portion 45 with the outer cylinder 20 increased in temperature, the outer cylinder 20 is cooled and the inner cylinder 10 is indirectly cooled. Water, the air, or oil can be used as the cooling medium. The planar portion 20s of the outer cylinder 20 corresponds to a “first planar portion” according to the present invention, and the planar portion 41a of the cooling device 40 corresponds to a “second planar portion” according to the present invention.

[0047] The tubular portion 45 can be formed into not the substantially U shape as described above but a zigzag shape or a linear shape.

[0048] FIG. 1A to 1D illustrate the case where the cooling device 40 is mounted on the outer cylinder 20 in a state where the planar portion 41a directly abuts against the planar portion 20s of the outer cylinder 20. Preferable adhesion is provided because the planar portions (the planar portion 41a and the planar portion 20s) abut against each other, so that the cooling device 40 can cool the outer cylinder 20 efficiently, and eventually, can indirectly cool the inner cylinder 10 efficiently.

[0049] A graphite sheet 50 may be interposed between the planar portion 41a of the cooling device 40 and the planar portion 20s of the outer cylinder 20, as illustrated in FIG. 2B. Since the graphite sheet 50 has flexibility and softness, the graphite sheet is brought into close contact with each of the planar portions 20s and 41a even if the planar portion 20s and the planar portion 41a are not smooth surfaces like mirror-polished surfaces. The cooling device 40 and the outer cylinder 20 can be brought into close contact with each other by heat conduction through the graphite sheet excellent in heat conductivity interposed therebetween.

[0050] The cooling device 40 can be mounted on the outer cylinder 20 in the molten metal receiving region not at a position just under the inlet port 30 but at a position deviating to one side from the vertical line Z from the center of the inlet port 30. The mounting manner is based on the finding that the portion of the inner surface of the cylinder portion, which is damaged due to supply of the molten metal to the sleeve, not only is located just under the inlet port as considered by those skilled in the art so far but also reaches the position deviating to one side.

[0051] As a reason for this, as illustrated in FIG. 3, a position at which the inlet port 30 is opened in the general die casting device DM is considered to be in the vicinity of a fixing platen 121 supporting the fixed mold 111 configuring a metal mold, a frame 122 for supporting a drive device (not illustrated) for driving the plunger tip 70 on the fixing platen 121, and the like. A device (not illustrated) moving the ladle 130 for pouring the molten metal to the inlet port 30 therefore interferes with the fixing platen 121 and the frame 122. Accordingly, it is difficult to move the ladle 130 to the position just above the inlet port 30, and as schematically illustrated in FIG. 4, the molten metal is poured to the inlet port 30 from the obliquely upper side with tilting of the ladle 130. As a result, the temperature of the inner surface of the cylinder portion 1 is the highest at not the position just under the inlet port 30 but the portion deviating to one side from the vertical line Z, and the portion tends to be damaged.

[0052] In consideration of this, the position of the cooling device 40 can be set such that an angle β formed by a line connecting a center line C of the cooling device 40 and the center axis X of the cylinder portion 1 and the vertical line Z from the inlet port 30 is 0 degrees to 60 degrees to one side on a cross section orthogonal to the center axis X, as illustrated in FIG. 4. More desirably, the center line of the cooling device 40 is set in a range R2 where the angle β is 0 degrees to 60 degrees to one side.

[0053] With the sleeve S1 in the embodiment, the material of the inner cylinder 10 is set to the TC composite material in at least the molten metal receiving region increased in temperature when the molten metal is supplied, and the cooling device 40 cools the outer cylinder 20 in the molten metal receiving region, that is, the inner cylinder 10 made of the TC composite material having low heat conductivity is indirectly cooled from the outer side to thereby cool the TC composite material to some extent that the temperature of the molten metal is not lowered. Therefore, damage of the inner cylinder can be effectively suppressed while suppressing generation of solidified pieces, thereby increasing the durability of the sleeve.

[0054] The cooling device 40 is mounted on the planar portion 20s formed on the outer cylinder 20, so that the cooling device 40 can be prevented from largely projecting from the cylinder portion 1 to achieve a compact structure reduced in weight. Furthermore, the jacket main body 41 as the metal block has the flat rectangular parallelepiped shape including the pair of planar portions 41a. Therefore, processing is easier than that in the case of a jacket main body having a circular arc-shaped cross section so as to externally surround the cylinder portion 1, and processing of providing the tubular portion 45 in the jacket main body 41 is also easy.

[0055] Moreover, the outer cylinder 20 and the cooling device 40 make contact with each other with abutment between the planar portion 20s and the planar portion 41a, thereby easily enhancing the adhesion and increasing the cooling efficiency of the outer cylinder 20 by the cooling device 40. In addition, when the graphite sheet 50 is interposed between the planar portion 20s and the planar portion 41a, the planar portion 20s and the planar portion 41a can be brought into close contact with each other by heat conduction through the graphite sheet 50 interposed therebetween even if the smoothness of the planar portion 20s and the planar portion 41a is not so high, and the cooling device 40 can cool the outer cylinder 20 more efficiently. The cooling device 40 can cool the outer cylinder 20 efficiently, so that the inner cylinder 10 can be indirectly cooled from the outer side effectively.

[0056] Furthermore, the planar portion 20s is formed on the outer cylinder 20, and the cooling device 40 is externally mounted thereon. With this configuration, the sleeve S1 can include the cooling device 40 with no problem even when the thickness of the outer cylinder 20 is small unlike the case where the tubular portion is provided in the outer cylinder.

[0057] Hereinbefore, the present invention has been explained using the preferred embodiment. The present invention is not however limited to the above-mentioned embodiment, and various improvements and changes in design can be made in a range without departing from the aspect of the present invention, as will be described below.

[0058] For example, a surface treatment layer by surface treatment such as nitriding treatment, carbonization treatment, and boride treatment can be provided on the inner surface of the inner cylinder 10.

[0059] Silicon carbide (SiC) is exemplified as the ceramic as the raw material of the TC composite material in the above description. The ceramic is however not limited thereto, and nitride-based ceramic such as Si.sub.3N.sub.4, TiN, and ALN, carbide-based ceramic such as TiC, B.sub.4C, and Crc.sub.2, boride-based ceramic such as ZrB.sub.2 and TiB.sub.2, oxide-based ceramic such as Cr.sub.2O.sub.3, Tio.sub.2, ZrO.sub.2, MgO, and Y.sub.2O.sub.3, or sialon can be used alone or some of them can be mixed and used.

[0060] Furthermore, the entire inner cylinder 10 is made of the TC composite material as the example in the above description. A peripheral edge portion of the inlet port 30 in the inner cylinder 10 can be made of steel. When the molten metal receiving region is extremely increased in temperature when the molten metal is supplied through the inlet port 30 whereas the liquid level of the molten metal does not reach an upper portion of the inner surface of the inner cylinder at a time point when the molten metal is supplied through the inlet port. Therefore, the peripheral edge portion of the inlet port is not so increased in temperature. As a result, the molten metal receiving region extremely increased in temperature thermally expands largely and extends largely also in the axial direction of the cylinder portion whereas the facing peripheral edge portion of the inlet port thermally expands to a small degree and less extends in the axial direction. An end portion of the sleeve on the inlet port side therefore tends to be deformed so as to warp upward.

[0061] In consideration thereof, thermal expansion in the molten metal receiving region and thermal expansion in the peripheral edge portion of the inlet port can be balanced more effectively by mounting the cooling device 40 on the outer cylinder 20 to cool the molten metal receiving region and forming the peripheral edge portion of the inlet port with steel having high heat conductivity, thereby suppressing deformation of upward warpage of the end portion on the inlet port side more effectively.