US20170008079A1

US20170008079A1 - Cast molding method and devices thereof

Info

Publication number: US20170008079A1
Application number: US14/793,906
Authority: US
Inventors: Tien-Ken Liang; Chun-Yung Huang; Ming-Chia Tsai; Weidong Xing; Ning Zhang
Original assignee: HER CHANG TECHNOLOGY Co Ltd
Current assignee: HER CHANG TECHNOLOGY Co Ltd
Priority date: 2015-07-08
Filing date: 2015-07-08
Publication date: 2017-01-12

Abstract

A cast molding method accomplishes the cast molding by a smelting chamber, a casting chamber, a hinge press system and a vacuum system. First, a metallic die is assembled in the casting chamber and then a metallic material is put in the smelting chamber. Next, the metallic material is heated up in a vacuum state and the casting chamber is pre-heated at a same time. After the metallic material in the smelting chamber has been melted down and the casting chamber has been vacuumized, the melted metallic material is filled into the metallic die, and then the hinge press system is turned on to cast mold the metallic die, resulting in a semi-solid product. After the semi-solid product has been cooled down, the product of cast molding is accomplished according to the present invention.

Description

BACKGROUND OF THE INVENTION

a) Field of the Invention

The present invention relates to a cast molding method and devices thereof, and more particularly to a cast molding method and devices thereof, which combine a casting process with a forging and stamping process for a metal to implement the metal forming once and for all, thereby shortening the forming process considerably and reducing the production cost.

b) Description of the Prior Art

A conventional small metal fitting, such as sport equipment (Golf head, striking surface), a housing structure (housing of an electronic part, housing of a watch), a small hardware fitting or an automobile part, will be manufactured by a technology of precision casting or precision die forging. For the precision casting, a casting mold is prepared first. The casting mold is provided with a mold cavity in a pre-determined specification of a product. Next, liquid wax is poured into the mold cavity of the casting mold to form a wax mold. The wax mold is then taken out of the mold cavity and submerged in a loam to form a polymer loam shell mold. After that, the shell mold is heated up to melt down the wax mold. The wax mold flows out of the ceramic shell mold, and a melted liquid metal is poured into the ceramic shell mold to form an embryo. Finally, the embryo is undergone with a few times of surface machining and then the product in the pre-determined specification can be made.
In the precision casting process, the production cycle of the shell mold is long and the technology is complicated. Furthermore, a loose and heavy resultant (α-Ti) will be created on the metal surface after casting. Therefore, the metal will have a poor mechanical strength and the shell mold can be used only once.
On the other hand, for the precision die forging process, a metal block made of carbon steel or alloy steel is first chosen for forging. The metal block is then undergone with a few times of forging and stamping process in a few forging dies. In the forging process, as the mold cavity of each forging die changes the shape orderly in a series, the outline of the metal block can be forged and stamped gradually and simultaneously into the embryo in the corresponding shape. Finally, the embryo is undergone with a few times of surface machining, and then the product in the pre-determined specification can be made.
Although the product of the forging formation is provided with the advantages of uniformity and high structural strength, as too many forging dies are used in the forging process, it can easily result in the shortcomings that the cost of die sinking and manufacturing can be too high, the forging process is not suitable for mass production, it is not easy to make complex shapes and the forging dies need to be replaced frequently due to deformation by pressure.

SUMMARY OF THE INVENTION

To solve this issue, the present invention provides a technical means which is able to combine the casting process with the forging and stamping process for a metal to implement the metal forming once and for all, thereby shortening the forming process considerably and reducing the production cost.
To achieve the abovementioned object, the present invention discloses a cast molding method which accomplishes the cast molding by a smelting chamber, a casting chamber, a hinge press system and a vacuum system. First, a metallic die is assembled in the casting chamber and then a metallic material is put in the smelting chamber. Next, the metallic material is heated up in a vacuum state and the casting chamber is pre-heated at a same time. After the metallic material in the smelting chamber has been melted down and the casting chamber has been vacuumized, the melted metallic material is filled into the metallic die, and then the hinge press system is turned on to cast mold the metallic die, resulting in a semi-solid product. After the semi-solid product has been cooled down, the product of cast molding is accomplished according to the present invention.
To achieve the abovementioned object, the present invention also discloses the devices of cast molding, including a smelting chamber, a casting chamber, a hinge press system and a vacuum system. The smelting chamber is provided with a roof, a crucible and a first heating unit. The first heating unit heats up the crucible and the roof is covered on a top of the smelting chamber. The casting chamber is disposed at a side of the smelting chamber and is provided with a holding space to accommodate the metallic die. The casting chamber is also provided with a guide tube which is connected to the crucible and the holding space. The hinge press system is disposed at a side of the casting chamber and is provided with a control unit, a second piping, a power unit and a hinge press bar. The second piping is connected respectively to the control unit and the power unit. The hinge press bar is connected with the power unit which provides power to the hinge press bar to move toward the holding space. The vacuum system vacuumizes respectively the smelting chamber and the casting chamber, and is provided with at least a vacuum pump.
To enable a further understanding of the said objectives and the technological methods of the invention herein, the brief description of the drawings below is followed by the detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of structures of devices of cast molding, according to the present invention.

FIG. 2 shows a block diagram of steps in the cast molding method, according to the present invention.

FIG. 3 shows a schematic view of metallographic structures of a product made of the cast molding method, according to the present invention.

FIG. 4 shows a schematic view of metallographic structures of a product made of the conventional precision casting process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, it shows a schematic view of structures of devices of the cast molding method, according to the present invention. The cast molding method accomplishes the cast molding with the cast molding devices including a smelting chamber 1, a casting chamber 2, a gas supply system 3, a hinge press system 4 and a vacuum system 5.
The smelting chamber 1 is provided with a roof 11, a crucible 12 and a first heating unit 13. The first heating unit 13 heats up the crucible 12 and the roof 11 is covered on a top of the smelting chamber 1 to seal the crucible 12. The first heating unit 13 can be a heating coil and is wrapped outside of the crucible 12.
The casting chamber 2 is disposed at a side of the smelting chamber 1. In the embodiment as shown in the drawing, the casting chamber 2 is located below the smelting chamber 1. The casting chamber 2 is provided with a holding space 21 to accommodate a metallic die 6, and a guide tube 22 which is connected to the crucible 12 and the holding space 21. The casting chamber 2 is further provided with a second heating unit (not shown in the drawing) to heat up the casting chamber 2. The second heating unit can be a heating coil or heating resistor.
The gas supply system 3 is disposed at a side of the smelting chamber 1 and is provided with a storage tank 31 and a first piping 32. The first piping 32 is connected to the storage tank 31 and the smelting chamber 1 to supply an anaerobic gas into the crucible 12, and the anaerobic gas is argon or nitrogen.
The hinge press system 4 is disposed at a side of the casting chamber 2 and is provided with a control unit 41, a second piping 42, a power unit 43 and a hinge press bar 44. The second piping 42 is connected respectively to the control unit 41 and the power unit 43; whereas, the hinge press bar 44 is connected to the power unit 43. The power unit 43 provides power to the hinge press bar 44 to move toward the holding space 21. The hinge press system 4 can be a hydraulic oil pressure system and the power unit 43 is a hydraulic pressure boosting cylinder. Moreover, in the embodiment as shown in the drawing, the hinge press bar 44 is located below the holding space 21. Naturally, the hinge press bar 44 can be also located next to the holding space 21.
The vacuum system 5 vacuumizes respectively the smelting chamber 1 and the casting chamber 2, and the vacuum system 5 is provided with at least a vacuum pump. In the embodiment as shown in the drawing, the vacuum system 5 is provided with a first vacuum pump 51 and a second vacuum pump 52. The first vacuum pump 51 is a mechanical pump and can form low vacuum in the smelting chamber 1 and the casting chamber 2. The second vacuum pump 52 is a Root's pump and can form high vacuum in the smelting chamber 1 and the casting chamber 2. By serially connecting the first vacuum pump 51 with the second vacuum pump 52, a system of large gas exhaust rate and high vacuum degree can be achieved.
Referring to FIG. 2, the cast molding method of the present invention includes following steps:
The metallic die 6 is provided and assembled into the holding space 21 of the casting chamber 2.
The crucible 21 is provided and assembled into the smelting chamber 1. A metallic material (not shown in the drawing) is loaded into the crucible 12 and the roof 11 is covered on the top of the smelting chamber 1 to seal the crucible 12. The crucible 12 is then vacuumized by the vacuum system 5 to the vacuum degree of 0.3×10⁻¹Pa˜1.0×10⁻¹Pa. The present invention utilizes at least a vacuum pump (such as mechanical pump and Root's pump) and can combine the vacuumizing abilities of different vacuum pumps to achieve the requirement of high vacuum or low vacuum. On the other hand, the metallic material that is loaded into the crucible 12 can be Titanium, Titanium alloy (such as Ti-6Al-4V), aluminum alloy or stainless steel.
The metallic die 6 is heated up to 40° C. to 500° C. by the second heating unit.
When the vacuum degree in the crucible 12 reaches 0.3×10⁻¹Pa˜1.0×10⁻¹Pa, the vaccumizing to the crucible 12 by the vacuum system 5 is stopped.
The gas supply system 3 supplies an anaerobic gas into the crucible 12. At this time, when the crucible 12 reaches the vacuum degree of 0.3×10⁻¹Pa˜1.0×10⁻¹Pa, the crucible 12 is filled with the anaerobic gas (can be argon or nitrogen) and an anoxic environment is formed inside the crucible 12. Therefore, in the subsequent heating step, the metallic material in the crucible 12 can be prevented from oxidation.
The crucible 12 is heated up to the melting point of the metallic material by the first heating unit 13 to melt down the metallic material. For example, if the metallic material that is put in the crucible 12 is Titanium alloy, then the heating temperature should reach 1600° C. to 1800° C. that the metallic material can be melted down completely.
The metallic die 6 in the casting chamber 2 is vacuumized to the vacuum degree of 0.3×10⁻¹Pa˜1.0×10⁻¹Pa by the vacuum system 5, forming an anoxic environment inside the metallic die 6.
The melted metallic material in the crucible 12 is filled into the metallic die 6 through the guide tube 22. At this time, the melted metallic material is at higher temperature (if the metallic material is Titanium alloy, then the temperature will reach about 1600° C. to 1800° C.), and as the metallic die 6 is at temperature of 40° C. to 500° C., it is equipped with a cooling function; therefore, after the melted metallic material has been filled into the metallic die 6, a semi-solid state can be formed to the metallic material, thereby accomplishing the casting procedure.
After that, the hinge press system 4 is turned on to forge the metallic die 6. By using the control unit 41 to control the power unit 43, the hinge press bar 44 will move toward the metallic die 6 and provide pressure to accomplish the semi-solid product. The control unit 41 can control and adjust the setting of pressure and time that the power unit 43 provides.
The product is accomplished after the semi-solid product has been cooled down. The product to which the present invention applies includes sport equipment (Gold head, striking surface), a housing structure (housing of an electronic part, housing of a watch), a small hardware fitting and an automobile part. By the forming method and the devices of the present invention, an anoxic environment is provided when the metallic material is melted and cooled down in the casting procedure, and an anoxic environment is also provided during forging formation. Therefore, it can assure that the metallic material will not be oxidized in the casting and forging procedures, so that the product will not form a loose resultant easily by oxidation, thereby improving the mechanical strength and extensibility of the product.
Referring to FIG. 3, it shows a schematic view of metallographic structures of a product made of the cast molding method, according to the present invention; whereas, FIG. 4 shows a schematic view of metallographic structures of a product made of the conventional precision casting process. The product of cast molding of the present invention is constituted by complex structures which are all formed by non-isometric columnar crystal structures 71 and isometric crystal structures 73. On the other hand, in the product of the conventional precision casting process, the distribution area of the resultants (α-Ti) 72 that are all made of the isometric crystal structures 73 is larger and heavier. In addition, the product of the cast molding of the present invention and the product of the conventional precision casting process are tested for tensile strength, yield strength and strain respectively. The results of test are shown in the following table.

TABLE 1

Tensile Strength	Yield Strength	Strain
(RmMPa)	(Rp0.2 MPa)	A(%)

Product of Cast	983.3	866	11.83
Molding of the
Present
Invention
Product of	951.6	848.3	7.67
Conventional
Precision
Casting Process
Rate of Increase	+3.3%	+2.1%	+54.2%

From the test results in Table 1, it is known that in comparison with the product of the conventional precision casting process, the tensile strength, yield strength and strain are all improved for the product of the cast molding of the present invention.
It is of course to be understood that the embodiments described herein is merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

What is claimed is:

1. A cast molding method accomplishing the cast molding by a smelting chamber, a casting chamber, a hinge press system and a vacuum system, and the cast molding method comprising following steps:

providing a metallic die and assembling the metallic die in the casting chamber;

providing a crucible and assembling the crucible in the smelting chamber, then loading a metallic material in the crucible and vacuumizing the smelting chamber using the vacuum system;

heating up the metallic die to 40° C. to 500° C.;

heating up the crucible to the melting point of the metallic material to melt down the metallic material;

vacuumizing the metallic die in the casting chamber using the vacuum system;

filling the metallic die with the melted metallic material in the crucible;

turning on the hinge press system to forge the metallic die, accomplishing a semi-solid product; and

accomplishing the product after the semi-solid product has been cooled down.

2. The cast molding method according to claim 1, further including a gas supply system to provide an anaerobic gas into the crucible.

3. The cast molding method according to claim 2, wherein the anaerobic gas supplied by the gas supply system is argon or nitrogen.

4. The cast molding method according to claim 1, wherein the vacuum system vacuumizes the crucible to a vacuum degree of 0.3×10⁻¹Pa˜1.0×10⁻¹Pa.

5. The cast molding method according to claim 1, wherein the vacuum system vacuumizes the metallic die to a vacuum degree of 0.3×10⁻¹Pa˜1.0×10 ⁻¹Pa.

6. The cast molding method according to claim 4, wherein the vacuum system is provided with at least a vacuum pump.

7. The cast molding method according to claim 6, wherein the vacuum system is provided with a first vacuum pump and a second vacuum pump.

8. The cast molding method according to claim 7, wherein the first vacuum pump is a mechanical pump which forms low vacuum in the smelting chamber and the casting chamber.

9. The cast molding method according to claim 7, wherein the second vacuum pump is a Root's pump which forms high vacuum in the smelting chamber and the casting chamber.

10. The cast molding method according to claim 1, wherein the metallic material is Titanium, Titanium alloy, aluminum alloy or stainless steel.

11. The cast molding method according to claim 1, wherein the metallic material is Titanium alloy and the crucible is heated up until the Titanium alloy reaches 1600° C. to 1800° C.

12. Devices of the cast molding method, comprising:

a smelting chamber, the smelting chamber being provided with a roof, a crucible and a first heating unit, with the first heating unit heating up the crucible and the roof being covered on a top of the smelting chamber;

a casting chamber, the casting chamber being disposed at a side of the smelting chamber and being provided with a holding space to accommodate the metallic die, with the casting chamber also being provided with a guide tube connecting the crucible and the holding space;

a hinge press system, the hinge press system being disposed at a side of the casting chamber and being provided with a control unit, a second piping, a power unit and a hinge press bar, with the second piping being connected respectively to the control unit and the power unit, the hinge press bar being connected with the power unit to provide power to the hinge press bar to move toward the holding space; and

a vacuum system, the vacuum system vacuumizing the smelting chamber and the casting chamber respectively, and being provided with at least a vacuum pump.

13. The devices of the cast molding method according to claim 12, further including a gas supply system, with the gas supply system being disposed at a side of the smelting chamber and being provided with a storage tank and a first piping, with the first piping being connected to the storage tank and the smelting chamber to supply an anaerobic gas into the crucible.

14. The devices of the cast molding method according to claim 12, wherein the vacuum system is provided with a first vacuum pump and a second vacuum pump.

15. The devices of the cast molding method according to claim 14, wherein the first vacuum pump is a mechanical pump which forms low vacuum in the smelting chamber and the casting chamber.

16. The devices of the cast molding method according to claim 14, wherein the second vacuum pump is a Root's pump which forms high vacuum in the smelting chamber and the casting chamber.

17. The devices of the cast molding method according to claim 12, wherein the hinge press system is a hydraulic oil pressure system.

18. The devices of the cast molding method according to claim 12, wherein the power unit is a hydraulic pressure boosting cylinder.

19. The devices of the cast molding method according to claim 12, wherein the casting chamber further includes a second heating unit.

20. The devices of the cast molding method according to claim 19, wherein the second heating unit is a heating coil or heating resistor.

21. The devices of the cast molding method according to claim 12, wherein the first heating unit is a heating coil and is wrapped outside of the crucible.

22. The devices of the cast molding method according to claim 12, wherein the hinge press bar is disposed below the holding space or is disposed next to the holding space.