Multiple pressure casting mold and molded product manufacturing method using same

Abstract

A multiple pressure casting mold includes a mold part having upper and lower molds, each having molten metal injection ports and the molded product accommodating parts for accommodating the molten metal for the molded product, a rotating unit for rotating the mold part so as to allow the molten metal injected through the molten metal injection ports to flow into the molded product accommodating parts, and a molten metal injection control unit having upper and lower pressing parts for pressing the molten metal injected through the molten metal injection ports so as to allow the molten metal to flow into the molded product accommodating parts with the rotating unit.

Claims

1. A multiple pressure casting mold comprising: a mold part including upper and lower molds, each having molten metal injection ports and molded product accommodating parts for accommodating molten metal for a molded product; a rotary unit including a rotary body supporting the mold part on a bottom side of the mold part and configured to rotate the mold part so as to allow the molten metal injected through the molten metal injection ports to flow into the molded product accommodating parts; and a molten metal injection control unit for pressurizing the molten metal injected through the molten metal injection ports so as to allow the molten metal to flow into the molded product accommodating parts, together with the rotary unit, the molten metal injection control unit including a sub-frame disposed on and extending upward from the upper mold, upper and lower pressurizing cylinders, and upper and lower pressurizing parts, wherein the upper pressurizing cylinder is fixedly attached to the sub-frame such that the upper pressurizing cylinder rotates along with the upper mold, and the lower pressurizing cylinder is fixedly attached to the rotary body of the rotary unit such that the lower pressurizing cylinder rotates along with the rotary body, and wherein the upper pressurizing part is attached to a cylinder rod of the upper pressurizing cylinder, and the lower pressurizing part is attached to a cylinder rod of the lower second pressurizing cylinder.

2. The multiple pressure casting mold according to claim 1, wherein the upper and lower pressurizing parts of the molten metal injection control unit are configured to move up and down in the molten metal injection ports, respectively, so as to connect or disconnect the molten metal injection ports and the molded product accommodating parts.

3. The multiple pressure casting mold according to claim 1, wherein the upper and lower pressurizing parts of the molten metal injection control unit are configured to move up and down in the molten metal injection ports, respectively, so as to open or close a riser between the molten metal injection ports and the molded product accommodating parts.

4. The multiple pressure casting mold according to claim 1, wherein the mold part further includes a sleeve attached to the molten metal injection ports and through which the molten metal is able to be injected, wherein the sleeve is provided with an electromagnetic field transmission part through which an electromagnetic field is transmitted.

5. The multiple pressure casting mold according to claim 4, wherein the sleeve is formed from an electromagnetic field-shielding material having a hollow cylindrical shape whose upper and lower parts are opened, wherein the electromagnetic field transmission part is provided with a plurality of holes perforated at regular intervals along the sleeve, and a plurality of filler parts formed from an electromagnetic field transmitting material and filling the plurality of holes.

6. The multiple pressure casting mold according to claim 4, wherein the sleeve is made from any one of SKD61 and STD61, and the filler parts are formed from silicone.

7. The multiple pressure casting mold according to claim 4, wherein an electromagnet module is disposed around the sleeve.

8. The multiple pressure casting mold according to claim 1, wherein the molten metal injection ports include first and second molten metal injection ports passing along a central rotary axis of the upper and lower molds, respectively, wherein the upper mold is provided, on a bottom surface thereof, with one or more first casting grooves and one or more first molten metal distribution passages respectively connecting the first casting grooves and the first molten metal injection port, wherein the lower mold is provided, on a top surface thereof, with one or more second casting grooves and one or more second molten metal distribution passages respectively connecting the second casting grooves and the second molten metal injection port, such that the first and second casting grooves and the first and second molten metal distribution passages are respectively formed to correspond to each other, and wherein, when the upper and lower molds are engaged, the first and second casting grooves facing each other form the molded product accommodating parts, and the first and second molten metal distribution passages facing each other form risers.

9. The multiple pressure casting mold according to claim 8, wherein first and second inner cores are respectively attached to the first and second casting grooves.

10. The multiple pressure casting mold according to claim 1, wherein the upper and lower pressurizing parts are disposed such that the upper and lower pressurizing parts are able to move in and out of the first and second molten metal injection ports along a central rotary axis of the upper and lower molds without interfering with rotation of the rotary unit.

11. A molded product manufacturing method using the multiple pressure casting mold according to claim 1, the method comprising: engaging the upper and lower molds such that first and second casting grooves face each other to form the molded product accommodating parts and first and second molten metal distribution passages face each other to form risers, wherein the risers connect the molten metal injection ports and the molded product accommodating parts; moving up the lower pressurizing part in the molten metal injection ports such that the lower pressurizing part closes off the risers from the molten metal injection ports; injecting the molten metal into the molten metal injection ports; moving down the upper pressurizing part in the molten metal injection ports while rotating the mold part such that with the lower pressurizing part being moved down, the molten metal is introduced into the molded product accommodating parts through the risers; and after the molten metal is solidified in the molded product accommodating parts, disengaging the upper mold from the lower mold.

12. The molded product manufacturing method according to claim 11, wherein when moving down the upper pressurizing part in the molten metal injection ports, a bottom surface of the upper pressurizing part coincides with a surface of the molten metal.

13. The molded product manufacturing method according to claim 11, wherein when moving down the upper pressurizing part in the molten metal injection, the lower pressurizing part is moved down until a top surface of the lower pressurizing part coincides with a position corresponding to a bottom edge of the risers.

14. The molded product manufacturing method according to claim 13, wherein when the top surface of the lower pressurizing part coincides with the bottom edge of the risers, the lower and upper pressurizing parts pressurize the molten metal at the same pressure.

15. A molded product manufacturing method using the multiple pressure casting mold according to claim 1, the method comprising: engaging the upper and lower molds such that first and second casting grooves face each other to form the molded product accommodating parts and first and second molten metal distribution passages face each other to form risers, wherein the risers connect the molten metal injection ports and the molded product accommodating parts; moving down the lower pressurizing part in the molten metal injection ports such that a top surface of the lower pressurizing part is positioned below a bottom edge of the risers; injecting the molten metal into the molten metal injection ports such that the molten metal is disposed between the top surface of the lower pressurizing part and the bottom edge of the risers; moving down the upper pressurizing part in the molten metal injection ports such that the upper pressurizing part closes off the risers from the molten metal injection ports; moving up the lower pressurizing part in the molten metal injection ports while rotating the mold part such that with the upper pressurizing part being moved up, the molten metal is introduced into the molded product accommodating parts through the risers; and after the molten metal is solidified in the molded product accommodating parts, disengaging the upper mold from the lower mold.

16. The molded product manufacturing method according to claim 15, wherein when moving up the lower pressurizing part in the molten metal injection, the upper pressurizing part is moved up until a bottom surface of the upper pressurizing part coincides with a position corresponding to a top edge of the risers.

17. The molded product manufacturing method according to claim 16, wherein when the bottom surface of the upper pressurizing part coincides with the top edge of the risers, the lower and upper pressurizing parts pressurize the molten metal at the same pressure.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a cross-sectional view schematically illustrating a multiple pressure casting mold according to embodiments of the present invention;

(2) FIG. 2 is an enlarged cross-sectional view illustrating the multiple pressure casting mold of FIG. 1;

(3) FIG. 3 is a perspective view illustrating a sleeve shown in FIG. 1;

(4) FIG. 4 is a process diagram illustrating a first embodiment of a molded product manufacturing method using the multiple pressure casting mold of FIG. 1;

(5) FIG. 5 is a process diagram illustrating a second embodiment of a molded product manufacturing method using the multiple pressure casting mold of FIG. 1;

(6) FIG. 6 is a process diagram illustrating a third embodiment of a molded product manufacturing method using the multiple pressure casting mold of FIG. 1; and

(7) FIG. 7 illustrates the comparison of simulation results between molten metal flows according to the present multiple pressure casting and a conventional centrifugal casting, and the comparison between motor rotors actually manufactured by the both methods.

BEST MODE

(8) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like parts are designated as like reference numerals throughout the drawings. Further, details of known functions and configurations that may make the gist of the present invention unnecessarily unclear will be omitted.

(9) FIGS. 1 and 2 show a multiple pressure casting mold according to embodiments of the present invention, which includes a mold part 110 having one or more cavities 120 therein, and a molten metal injection control unit 130 that provides molten metal injected into the mold part 110 with centrifugal force and pressure during casting and allows the molten metal to flow into the cavities 120.

(10) The mold part 110 includes upper and lower molds 112a and 112b disposed in a vertical direction.

(11) When engaged (assembled), the upper and lower molds 112a and 112b define one or more molded product accommodating parts (also referred to as cavities) 120 in which a molded product is casted. To this end, the upper and lower molds 112a and 112b are respectively provided with first and second molten metal injection ports 114a and 114b passing along a central rotary axis CL. In addition, the upper mold 112a is provided, on a lower surface thereof, with one or more first casting grooves 116a and first molten metal distribution passages 118a respectively connecting the first casting grooves 116a and the first molten metal injection port 114a. Similarly, the lower mold 112b is provided, on an upper surface thereof, with one or more second casting grooves 116b and second molten metal distribution passages 118b respectively connecting the second casting grooves 116b and the second molten metal injection port 114b, such that the first and second casting grooves 116a and 116b and the first and second molten metal distribution passages 118a and 118b are respectively formed to correspond to each other.

(12) When the upper and lower molds 112a and 112b are engaged, the first and second casting grooves 116a and 116b facing each other form the cavities 120, and the first and second molten metal distribution passages 118a and 118b facing each other form the risers 122.

(13) That is, the molten metal is supplied into and fills the first and second molten metal injection ports 114a and 114b from an upper portion of the first molten metal injection port 114a when the upper and lower molds 112a and 112b are engaged, molten metal, or otherwise is injected into the second molten metal injection port 114b from an upper portion of the second molten metal injection port 114b and then fills the second molten metal injection port 114b when the upper mold 112a is engaged with the lower mold 112b. During casting, the filled molten metal is distributed and injected into the cavities 120 via the risers 122 connected to the cavities with the operation of a molten metal injection unit 130.

(14) Here, respective risers 122 connected to the cavities 120 are passages diverging from inlets thereof connected to the first and second molten metal injection ports 114a and 114b towards outlets thereof connected to the cavities 120 in order for easy injection of the molten metal.

(15) The first and second casting grooves 116a and 116b are respectively surface-coated with first and second inner cores 124a and 124b formed from ceramics or the like in order to protect the cavities 120 from high temperature molten metal when the upper and lower molds 112a and 112b are engaged.

(16) The electromagnet module 150 is provided around the first molten metal injection port 114a formed in the upper mold 112a so as to generate an electromagnetic field from an external power source, and a sleeve 152 (see FIG. 3) is provided in the first molten metal injection port 114a, without interfering with the injection of the molten metal, so as to allow the electromagnetic field generated from the electromagnet module 150 to be collected in the first molten metal injection port 114a.

(17) As shown in FIG. 3, the sleeve 152 has a hollow cylindrical shape having upper and lower openings. The sleeve 152 is formed from hot-worked mold steel such as SKD61, STD61, or the like that is an electromagnetic field-shielding material. Here, the sleeve 152 has an electromagnetic field passage part 154 through which an electromagnetic field generated from the electromagnet module 150 is guided towards the first molten metal injection port 114a.

(18) The electromagnetic field passage part 154 is provided with a plurality of holes 156 perforated at regular intervals along the sleeve 152, and a plurality of filler parts 158 formed from an electromagnetic field transmitting, heat-resistant material, such as silicone, and that fill the plurality of holes 156.

(19) Like this, the sleeve 152 and electromagnet module 150 disposed around the first molten metal injection port 114a apply an electromagnetic field to the molten metal so as to change the molten metal to a semi-solidified metal while controlling the state of the molten metal (breakage of a dendritic microstructure, or grain refining by control of nucleation density and growth rate). Since the semi-solidified molten metal becomes solidified directly after being introduced into the cavities 120, a casting time can be shortened.

(20) In addition, the application of the electromagnetic field to the injected molten metal reduces defects that may occur in a molded product and the grain refining may improve a variety of mechanical properties, thereby increasing the degree of freedom in designing a molded product (casting).

(21) The mold part 110 further includes a mold coupler 126 that can connect or disconnect the upper and lower molds 112a and 112b.

(22) The mold coupler 126 may have a variety of configurations. In an embodiment of the present invention shown in FIG. 1, the mold coupler 126 comprises an hydraulic cylinder device that is mounted to a rotary body 132 of a rotary section 131 in a molten metal injection control unit 130, which will be described later, so as to connect or disconnect the upper mold 112a to or from the lower mold 112b by moving up and down the upper mold 112a. However, it will apparent to those skilled in the art that the mold coupler 126 is not limited to the above-mentioned hydraulic cylinder device.

(23) That is, any configuration may be employed if it is able to connect or disconnect the upper mold 112a to or from the lower mold 112b without interfering with the operation of the molten metal injection control unit 130.

(24) The molten metal injection control unit 130 includes a rotary section 131 having a rotary body 132 to rotate the mold part 110 and allow the molten metal injected into the mold part 110 to be introduced into the cavities 120 during casting, and upper and lower pressurizing parts 136a and 136b pressurizing and introducing the molten metal in the mold part 110 towards the cavities 120 during casting. Here, the upper and lower pressurizing parts 136a and 136b may be a conventional plunger.

(25) As shown, the rotary body 132 is disposed below the mold part 110. The rotary body 132 is rotatably supported by a frame F1 fixed to the ground or the like, and the lower mold 112b of the mold part 110 is detachably mounted to the rotary body 132 by a conventional clamping unit (not shown). Although the clamping unit is not illustrated in FIGS. 1 and 2, the clamping unit may have any configuration if it is able to detachably attach the lower mold 112b to the rotary body 132. Thus, the present invention does not limit the clamping unit to a specified configuration.

(26) Further, the rotary body 132 is driven and rotated by a drive motor 134 supported by the frame F1 via a conventional power transmission, such as a belt and pulley, a sprocket and chain, a gear, or the like.

(27) The upper and lower pressurizing parts 136a and 136b are disposed such that they can move in and out of the first and second molten metal injection ports 114a and 114b along a central rotary axis (CL) of the upper and lower molds 112a and 112b without interfering with the rotation of the rotary body 132. To this end, the upper pressurizing part 136a is attached to a first cylinder rod 140a of a first pressurizing cylinder 138a disposed upwards from the upper mold 112a, and the lower pressurizing part 136b is attached to a second cylinder rod 140b of a second pressurizing cylinder 138b disposed downwards from the lower mold 112b.

(28) Here, the first pressurizing cylinder 138a is fixedly attached to a sub-frame F2 extending upwards from the upper mold 112a such that the first pressurizing cylinder can rotate together with the mold part 110 while pressurizing the molten metal, without contacting the first molten metal injection port 114a, and the second pressurizing cylinder 138b is fixedly attached to the inside of the rotary body 132 such that the second pressurizing cylinder can rotate together with the mold part 110.

(29) The upper and lower pressurizing parts 136a and 136b attached to the first and second pressurizing cylinders 138a and 138b serve to pressurize and introduce the molten metal in the first and second molten metal injection ports 114a and 114b into the cavities 120 with the operation of the first and second pressurizing cylinders 138a and 138b during casting.

(30) That is, the molten metal injected into the mold part 110 is introduced into the cavities 120 by a combination of operations of the rotary body 132 and the upper and lower pressurizing parts 136a and 136b during casting.

(31) Hereinafter, a molded product manufacturing method using the multiple pressure casting mold 100 having the above-mentioned configuration will be described.

(32) FIG. 4 is a process diagram illustrating a first embodiment of the molded product manufacturing method using the multiple pressure casting mold of FIG. 1. The manufacturing method using the mold 100 includes engaging (assembling) the upper and lower molds 112a and 112b (S11).

(33) The engagement of the upper and lower molds 112a and 112b is performed by attaching the lower mold 112b to the rotary body 132 and then moving down the upper mold 112a towards the lower mold 112b. That is, the upper mold 112a is engaged with the lower mold 112b by activating the mold coupler 126 attached to the upper mold 112a in a moving-down direction.

(34) Here, the engagement of the upper and lower molds 112a and 112b is performed in a state in which the first and second inner cores 124a and 124b are attached to the first and second casting grooves 116a and 116b.

(35) When the upper and lower molds 112a and 112b are engaged (S11), the lower pressurizing part 136b is moved upwards so as to prevent molten metal from flowing into the risers 122 connected to the first and second molten metal injection ports 114a and 114b (S12). Then, after a liquefied molten metal is injected towards the upper portion of the lower pressurizing part 136b (S13), the upper pressurizing part 136a is moved down into the first molten metal injection port 114a such that a lower surface of the upper pressurizing part 136a contacts a surface of the molten metal (S14).

(36) Here, the molten metal in Stage S13 is injected into and fills the first molten metal injection port 114a, and then is changed into a semi-solidified molten metal by being electromagnetically stirred by the electromagnet module 150 while being cooled.

(37) As described above, when the lower surface of the upper pressurizing part 136a coincides with the surface of the molten metal (S14), the upper pressurizing part 136a is moved down such that the molten metal is introduced towards the riser 122 closed by the lower pressurizing part 136b, and the upper and lower molds 112a and 112b, which are engaged, are rotated at high speed, such that the molten metal filling the inside of the first molten metal injection port 114a is solidified while being introduced into the cavities 120 (S15).

(38) In S15, an upper surface of the lower pressurizing part 136b is moved down up to and fixed to a position corresponding to the bottom of the riser 122 by the upper pressurizing part 136a that is moving down while pressurizing the molten metal, and then the molten metal is solidified while being introduced into the cavities 120 along the riser 122 by the upper pressurizing part 136a that is continuously moving down.

(39) In the meantime, in S15, when the upper surface of the lower pressurizing part 136b coincides with the bottom of the riser 122 by the action of the upper pressurizing part 136a that is moving down while pressurizing the molten metal, or otherwise the lower surface of the moving-down upper pressurizing part 136a coincides with an upper surface of the riser 122, the lower and upper pressurizing parts 136b and 136a pressurize the molten metal at the same pressure.

(40) That is, the molten metal filling the mold part 110 is solidified while being injected towards the cavities 120 by centrifugal force provided during rotation of the rotary body 132 and pressurizing force applied between the upper and lower pressurizing parts 136a and 136b.

(41) When the molten metal is introduced into the cavities 120 and is solidified as described above (S15), the upper mold 112a is disengaged from the lower mold 112b and then a solidified molded product is removed from the lower mold 112b, thereby completing the manufacture of the molded product (S16).

(42) According to the first embodiment of the molded product manufacturing method using the multiple pressure casting mold as described before, since the molten metal is introduced towards the cavities 120 with the combined action of centrifugal force generated during the operation of the rotary section 131 and pressurizing force of the upper pressurizing part 136a pressurizing the molten metal during casting, the molten metal can be introduced towards the cavities 120 in a continuous, uniform manner and a molten metal-filling rate can be increased as well, thereby manufacturing a high quality molded product.

(43) FIG. 5 is a process diagram illustrating a second embodiment of the molded product manufacturing method using the multiple pressure casting mold of FIG. 1. The manufacturing method using the mold 100 includes engaging (assembling) the upper and lower molds 112a and 112b (S21).

(44) The engagement of the upper and lower molds 112a and 112b is the same as that in S11 of the first embodiment, so a detailed description thereof will be omitted.

(45) When the upper and lower molds 112a and 112b are engaged (S21), the lower pressurizing part 136b is moved down such that the upper surface thereof is disposed below the riser 122 (S22), and then a liquefied molten metal is injected between the upper surface of the lower pressurizing part 136b and a lower section of the riser 122 (S23). Then, after the molten metal is completely injected (S23), the upper pressurizing part 136a is moved down into the first molten metal injection port 114a such that the lower surface thereof coincides with the surface of the molten metal while preventing the molten metal from being introduced into the riser 122 (S24).

(46) As described above, when the lower surface of the upper pressurizing part 136a coincides with the surface of the molten metal (S24), the lower pressurizing part 136b is moved up such that the molten metal is introduced towards the riser 122 closed by the upper pressurizing part 136a, and the upper and lower molds 112a and 112b, which are engaged, are rotated at high speed, such that the molten metal filling the inside of the second molten metal injection port 114b is solidified while being introduced into the cavities 120 (S25).

(47) In S25, the lower surface of the upper pressurizing part 136a is moved up and fixed to a position corresponding to the upper surface of the riser 122 by the lower pressurizing part 136b that is moving up while pressurizing the molten metal, and then the molten metal is solidified while being introduced into the cavities 120 along the riser 122 by the lower pressurizing part 136b that is continuously moving up.

(48) In the meantime, in S25, when the lower surface of the upper pressurizing part 136a coincides with the upper surface of the riser 122 by the action of the lower pressurizing part 136b that is moving up while pressurizing the molten metal, or otherwise the upper surface of the moving-up lower pressurizing part 136b coincides with the bottom of the riser 122, the lower and upper pressurizing parts 136b and 136a pressurize the molten metal at the same pressure.

(49) When the molten metal is introduced into the cavities 120 and is solidified as described above (S25), the upper mold 112a is disengaged from the lower mold 112b and then a solidified molded product is removed from the lower mold 112b, thereby completing the manufacture of the molded product (S26).

(50) According to the second embodiment of the molded product manufacturing method using the multiple pressure casting mold as described before, since the molten metal is introduced towards the cavities 120 with the combined action of centrifugal force generated during the operation of the rotary section 131 and pressurizing force of the lower pressurizing part 136b of the molten metal injection control unit 130 pressurizing the molten metal during casting, the molten metal can be introduced towards the cavities 120 in a continuous, uniform manner and a molten metal-filling rate can be increased as well, thereby manufacturing a high quality molded product.

(51) FIG. 6 is a process diagram illustrating a third embodiment of the molded product manufacturing method using the multiple pressure casting mold of FIG. 1. The manufacturing method using the mold 100 includes the lower pressurizing part 136b that is moved down such that the upper surface thereof is disposed below the riser 122 (S31), and then a liquefied molten metal is injected between the upper surface of the lower pressurizing part 136b and a lower section of the riser 122 (S32).

(52) After the molten metal is completely injected as described above (S32), the upper mold 112a is engaged with the lower mold 112b (S33), and then the upper pressurizing part 136a is moved down into the first molten metal injection port 114a such that the lower surface thereof coincides with the surface of the molten metal while preventing the molten metal from being introduced into the riser 122 (S34).

(53) S33 is the same as S11 of the first embodiment, so a detailed description thereof will be omitted.

(54) As described above, when the lower surface of the upper pressurizing part 136a coincides with the surface of the molten metal (S34), the lower pressurizing part 136b is moved up such that the molten metal is introduced towards the riser 122 closed by the upper pressurizing part 136a, and the upper and lower molds 112a and 112b, which are engaged, are rotated at high speed, such that the molten metal filling the inside of the second molten metal injection port 114b is solidified while being introduced into the cavities 120 (S35).

(55) In S35, the lower surface of the upper pressurizing part 136a is moved up and fixed to a position corresponding to the upper surface of the riser 122 by the lower pressurizing part 136b that is moving up while pressurizing the molten metal, and then the molten metal is solidified while being introduced into the cavities 120 along the riser 122 by the lower pressurizing part 136b that are continuously moving up.

(56) In the meantime, in S35, when the lower surface of the upper pressurizing part 136a coincides with the upper surface of the riser 122 by the action of the lower pressurizing part 136b that is moving up while pressurizing the molten metal, or otherwise the upper surface of the moving-up lower pressurizing part 136b coincides with the bottom of the riser 122, the lower and upper pressurizing parts 136b and 136a pressurize the molten metal at the same pressure.

(57) When the molten metal is introduced into the cavities 120 and is solidified as described above (S35), the upper mold 112a is disengaged from the lower mold 112b and then a solidified molded product is removed from the lower mold 112b, thereby completing the manufacture of the molded product (S36).

(58) According to the second embodiment of the molded product manufacturing method using the multiple pressure casting mold as described before, since the molten metal is introduced towards the cavities 120 with the combined action of centrifugal force generated during the operation of the rotary section 131 and pressurizing force of the lower pressurizing part 136b of the molten metal injection control unit 130 pressurizing the molten metal during casting, the molten metal can be introduced towards the cavities 120 in a continuous, uniform manner and a molten metal-filling rate can be increased as well, thereby manufacturing a high quality molded product.

(59) FIG. 7 shows simulation results of flowing of molten metal according to the multiple pressure casting method and a conventional centrifugal casting method. It could be seen that in the conventional centrifugal casting method, the molten metal does not uniformly fill the cavities since the filling is performed simply using a gravity force. On the contrary, according to the present casting method using the multiple pressure casting mold 100, it could be seen that, since the molten metal is pressurized by the molten metal injection control unit 130, the molten metal is injected into cavities 120 in a continuous, uniform manner. Further, it could be seen that the present casting method using the multiple pressure casting mold 100 shows a higher molten metal filling rate per a unit volume, compared to the conventional centrifugal casting method. As a result of an actual experiment, the present invention showed a molten metal filling rate that is increased by 5% to 10% or more, compared to the conventional centrifugal casting method.

(60) The aforementioned multiple pressure casting mold and the molded product manufacturing method using the same are not limited to configurations and operating manners of the aforementioned embodiments. The embodiments may also be implemented into a variety of modifications through a selective combination of all or some of the embodiments.

DESCRIPTION OF THE REFERENCE NUMERALS IN THE DRAWINGS

(61) 100: Multiple pressure casting mold 110: Mold part 112a: Upper mold 112b: Lower mold 114a: 1.sup.st molten metal injection port 114b: 2.sup.nd molten metal injection port 116a: 1.sup.st casting groove 116b: 2.sup.nd casting groove 118a: 1st molten metal distribution passage 118b: 2.sup.nd molten metal distribution passage 120: Molded product accommodating part (or Cavity) 122: Riser 124a: 1.sup.st inner core 124b: 2.sup.nd inner core 130: Molten metal injection control unit 132: Rotary body 134: Drive motor 136a: Upper pressurizing part 136b: Lower pressurizing part 138a: 1.sup.st pressurizing cylinder 138b: 2.sup.nd pressurizing cylinder 140a: 1.sup.st cylinder rod 140b: 2.sup.nd cylinder rod