Indian Patents. 253712:WIRE MESH FILTER FOR CASTING MACHINE

Title of Invention	WIRE MESH FILTER FOR CASTING MACHINE
Abstract	A filter body (35) is provided in the shape of a brimmed hat formed with a brim section (38) around the entire circumference of a hat body section (37) . Downward extensions (36) are provided extending downwardly from the peripheral portion of the filter body (35) . An annular concave section (39) is formed between the peripheral edge of the brim section 38 and the hat body section (37) .

Full Text	Specification WIRE MESH FILTER FOR CASTING MACHINE Field of the Invention [0001] This invention relates to a wire mesh filter mounted in a pouring gate of a casting machine for low pressure casting. Background Art [0002] Conventionally, the cylinder head of an engine for a motorcycle, for example, has been cast using a low pressure casting process . As a casting machine for low pressure casting, a system has been disclosed, for example, in JP-A-Hei 11-57979. The casting machine disclosed in Patent Document 1 is configured such that a crucible is disposed below a die made up of a lower and an upper die, molten metal stored in the crucible is pressurized and pushed up through a stalk and a pouring gate cup so as to be supplied to the pouring gate of the lower die. [0003] This type of casting machine has a wire mesh filter mounted in the pouring gate, as shown in FIG. 5, to prevent oxides produced in the crucible and the stalk or foreign matters in molten metal from flowing into the die together with the molten metal. FIG. 5 is a sectional view, showing an enlarged pouring gate section of a casting machine with a conventional filter mounted therein. In FIG. 5, reference numeral 1 designates a lower die, reference numeral 2 a lower die support member, reference numeral 3 a pouring gate cup, reference numeral 4 a filter, and reference numeral 5 molten metal already solidified in the die. [0004] The lower die 1 is formed such that its cavity 6 opens upwardly, and secured on a base plate (not shown) through the lower die support member 2. The cavity 6 is defined by the lower die and upper die (not shown) , and formed, at the lower end, with a runner 7. The runner 7 is formed in the lower die 1 such that it is recessed downwardly of a product part 8 shown in a double dot 1 and dash line in FIG. 5. A pouring gate 9 opens into the runner 7 at the bottom thereof. [0005] The pouring gate 9 is connected to the pouring gate cup 3 held in the lower die support member 2. The pouring gate cup 3 is connected, at its lower end, to a stalk, though not shown in the figure, and in communication with the crucible through the stalk. That is, in this casting machine, molten metal passing through the stalk is pushed up to the pouring gate cup 3, and supplied into the cavity 6 (runner 7) from the pouring gate cup 3 through the pouring gate 9. [0006] The pouring gate 9 is formed so as to gradually increase its opening diameter upwardly, and a filter 4 is mounted in the middle. The filter 4 is made from wire mesh into the shape of a bottomed cylinder by press forming. The filter 4 is formed integrally with a vertical extension 4a fitted in the pouring gate 9 and extending vertically, and a disc-like filter body 4b disposed, partitioning the pouring gate 9 in the vertical direction, at the upper end of the vertical extension 4a. The filter 4 is inserted and press-fitted in the pouring gate 9 from the side of the cavity 6 while pressed and elastically deformed by an worker. [0007] In this conventional casting machine, molten metal is supplied into the cavity 6 through the filter 4. When the cavity 6 is filled with the molten metal and the molten metal is solidified near the pouring gate 9, pressurization of the molten metal is stopped in the crucible. This stopping of pressurization causes unsolidified portion of the molten metal to flow down to the crucible, with solidified portion (molten metal 5) to be left in the die. In the conventional casting machine, pressurization time is set such that the filter 4 is in the solidified portion in an embedded relation with a cast product (see FIG. 5). Therefore, the filter 4 is removed from the pouring gate 9 together with the cast product when the cast 2 product is separated upwardly from the lower die 4 after casting process. Disclosure of the invention Problem to be Solved by the Invention [0008] In such a conventional casting machine as described above, the filter 4 is attached to the pouring gate 9 by an worker and the force applied to the filter 4 when it is press-fitted in the pouring gate 9 is different for each worker, so that there is the possibility of the filter 4 being attached in an inappropriate position. For example, when the filter 4 is mounted relatively near the runner 7 (upwardly in the figure), the force by which the filter 4 is secured inside the pouring gate 9 becomes smaller. In this case, there is the possibility of the filter 4 being pressed by molten metal during casting, to thereby slip off from the pouring gate 9 toward the runner 7 and enters the region of the product part 8. If the filter 4 enters the region of the product part 8, the cast product becomes defective. [0009] On the other hand, when the filter 4 is mounted at a position relatively near the pouring cup 3 (downwardly in the figure) , there is a possibility of failing to take the filter 4 into the solidified portion 5 of molten metal. In this case, the filter 4 remains in the pouring gate 9 after separation of the cast product from the die. Therefore, the casting machine must be stopped to remove the filter 4 before the next casting, preventing continuous operation of the casting machine. In the conventional casting machine, to avoid such a trouble, molten metal is pressurized until solidification of the molten metal reaches the bottom of the pouring gate 9, for the filter 4 not to remain in the pouring gate 9. Therefore, the use of the conventional wire mesh filter for a casting machine raises a problem that time needed for one casting operation (cycle time) is prolonged. [0010] 3 In order to solve the foregoing problems, an object of this invention is to provide a wire mesh filter for a casting machine in which slipping off of a filter from a pouring gate by the pressure of molten metal is prevented and the filter is allowed to be taken into the cast product even if the pressurization time of the molten metal is short. Means for Solving the Problem [0011] To achieve the foregoing object, this invention is directed to a wire mesh filter adapted to be fitted and mounted in a pouring gate of a casting machine for low pressure casting from the side of a runner, comprising: a filter body, in the shape of a brimmed hat, formed with a brim section around the entire circumference of the lower part of an upwardly convex hat body section; downward extensions extending downwardly from the peripheral portion of the filter body; and an annular concave section formed between the peripheral edge of said brim section and said hat body section. Effects of the Invention [0012] According to the invention, since the filter body having a bent portion acts as a spring capable of substantial elastic deformation in the radial direction, the spring force of the filter body in press contact with the inside wall of the pouring gate can be increased while the filter body is pressed in the pouring gate. Therefore, since the filter can be held firmly in the pouring gate, slipping off of the filter from the pouring gate by the pressure of molten metal during casting can be prevented reliably, improving the yield. [0013] In addition, since the hat body section of the filter body is protruded upwardly from the brim section fitted in the pouring gate, the hat body section can be adapted to extend at the upper end into the solidified portion of molten metal even when the filter body is located in the pouring gate at a relatively lower 4 part. Therefore, since part (hat) of the filter is in the solidified portion without need of waiting until the molten metal is solidified up to the region of the lower part of the pouring gate, time needed for one casting operation (cycle time) can be shortened. In addition, the filter can be removed reliably from the die together with a casting, preventing stopping an operation of the casting machine only for the removal of the filter from the die. Therefore, this is combined with shortening the cycle time described above, providing further improvement in productivity. [0014] According to the invention of Claim 2, the filter body can be positioned in the pouring gate at the runner-side opening edge using the brim section of the filter body as a reference. According to this invention, therefore, the filter body can be located at a constant position at all times such that the hat body section of the filter body extends into the runner, in spite of alternation of an worker who mounts the filter. Therefore, since pressurization of molten metal can be stopped when the molten metal is solidified in the runner, the timing at which pressurization of molten metal is stopped, can be advanced, compared with the timing at which the pressurization of the molten metal is stopped after solidification of the molten metal has reached the pouring gate. As a result, the cycle time can be shortened even further to improve production efficiency. [0015] According to the invention of Claim 3, resistance produced when the molten metal passes through the wire mesh filter can be minimized, and foreign matters in the molten metal can be reliably removed with the wire mesh filter. Brief Description of Drawings [0016] FIG. 1 is a sectional view of a casting machine for low pressure casting with a filter according to this invention. FIG. 2 is a plan view of a lower die. Fig. 3 is an enlarged sectional view, showing an essential 5 part. FIG. 4 is a perspective view of the filter. FIG. 5 is an enlarged sectional view, showing a pouring gate section of a casting machine having a conventional filter mounted thereon. Best Mode for Carrying Out the Invention [0017] Now, an embodiment of this invention is described with reference to the drawings. In FIGs . 1 through 4, designated by reference numeral 11 is a casting machine for low pressure casting of this embodiment. The casting machine 11 is one for casting a cylinder head (not shown) of an engine for a motorcycle by low pressure casting, and as has been well known, a die 13 is disposed above a furnace 12. [0018] The furnace 12 is composed of a body 14 formed in the shape of an upwardly opening box, a cover 15 for closing the upper opening section of the body 14, a crucible 17 for storing molten metal 16, a stalk 18 attached to the cover 15 and submerged at the lower end in the molten metal 16, and others. The body 14 of the furnace 12 contains a heater (not shown) for heating the molten metal 16 in the crucible 17 at a given temperature and is connected to a pressurization device (not shown). The pressurization device has a function of supplying inert gas into the body 14 during casting to pressurize the upper surface of the molten metal 16 and push up the molten metal 16 into the stalk 18, and a gas pipe (not shown) is connected to a connection port 14a formed in the body 14. [0019] Casting by the casting machine 11 is performed, as in the conventional casting machine, by pressurizing the interior of the body 14 of the furnace 12 by the pressurization device, with the die 13 clamped. During casting, the molten metal 16 is fed upward from the crucible 17 through the stalk 18 and supplied into the dies 13 located above them. 6 The dies 13 is composed of an upper die 21 and a lower die 22 and supported by a driving device 23. The upper die 21 is formed with a downwardly opening cavity 24, and attached to a platen 25 of the driving device 23. The platen 25 is supported on a base plate 26 of the driving device 23 through tie bars 27 for up and down movement and adapted to be moved vertically by a vertical feed motor (not shown). [0020] The lower die 22 is formed with an upwardly opening cavity 28, and secured on the base plate 26 through a support member 29. The lower die 22 and upper die 21 are each provided with a heater (not shown) for preheating the die to a casting temperature, and a water-cooling type cooling device (not shown) for keeping the die temperature constant during casting. In the bottom of the cavity 28 of the lower die 22 is formed a runner 30 extending from one side of the cavity 28 to the other side and a pouring gate 31 is formed extending downwardly from the bottom of the runner 30, as shown in FIG. 2 and FIG. 3. [0021] The pouring gate 31 formed in the bottom of the lower die 22 has an oval shape, as viewed from above in FIG. 2 . The diameter of the pouring gate 31 is gradually increased toward the upper end to form a draft as shown in FIG. 3. In the opening of the pouring gate 31 at the upper end is mounted a filter 32 (described later). To the lower end of the pouring gate 31 is connected the upper end of a pouring gate cup 33 provided in the lower die support member 29. The pouring gate cup 33, as shown in FIG. 1, penetrates the support member 29 in the vertical direction. The molten metal 16 is supplied into the pouring gate cup 33 from the upper end of the stalk 18 in abutment against the lower surface of the support member 29. That is, during casting, the molten metal 16 flows into the pouring gate 31 from the stalk 18 through the pouring gate cup 33, then into the runner 30 from the pouring gate 31 through the filter 32, to be supplied to cavities 24, 28. [0022] 7 The molten metal 16 which has filled up the cavities 24, 28, begins solidifying at the product part 34 (see FIG. 3) within the cavities 24, 28. Solidification of the molten metal 16 advances with time from inside the runner 30 to the pouring gate 31. The casting machine 11 of this embodiment stops pressurization by the pressurization device when solidification advances up to a region near the boundary between the runner 30 and pouring gate 31, causing an unsolidified portion of the molten metal 16 to flow down to the crucible 17. In this embodiment, the timing at which the pressurization is stopped, is determined based on the temperature of the molten metal 16 near the boundary detected by a temperature sensor (not shown) mounted on the lower die 22. [0023] The filter 32, as shown in FIG. 3 and FIG. 4, includes a filter body 35 in the shape of a brimmed hat, downward extensions 36 extending downwardly from the periphery of the filter body 35, and an annular concave section 39 (described later). The filter 32 of this embodiment is manufactured from a zinc-plated wire mesh, made of steel, being shaped by a pressurization-forming device (not shown). Although numerous auxiliary lines are depicted in FIG. 4 for easy understanding of the shape of the filter 32, the mesh of the filter 32 is formed from wire mesh woven in the directions different from those of the auxiliary lines. The experiment showed that using a wire mesh of a 4 through 12-inch mesh for the filter 32 can minimize the resistance produced when the molten metal passes therethrough and assure removal of foreign matters in the molten metal. Specifically, it was revealed that using a wire mesh of an 8-inch mesh for the filter 32 ensures the most effective removal of foreign matters. [0024] The filter body 35 has a hat body section 37 formed in the shape of an upwardly convex, bottomed cylinder, and a brim section 38 formed continuously around the entire circumference of the lower part of the hat body section 37, and has the shape 8 of a brimmed hat as a whole. The brim section 38 has the peripheral edge 38a connected to the downward extensions 36. The annular concave section 39 described above is formed between the peripheral edge 38a and the hat body section 37. The annular concave section 39 is open upward. [0025] In this embodiment, the peripheral edge 38a of the brim section 38 is curved gradually downwardly toward the outer end in the radial direction and smoothly connected to the upper end of the downward extensions 36. As described above, since the brim section 38 is curved at the peripheral edge 38a and the annular concave section 39 is located radially inwardly of the peripheral edge 38a, the brim section 38 is formed in the shape of a letter S in section by the annular concave section 39 located on the inside circumferential side and an annular convex section 40 located on the outside circumferential side. The brim section 38 has an outside diameter a little larger than the inside diameter of the runner-side opening edge of the pouring gate 31. The downward extensions 36 are portions corresponding to the four corners of a wire mesh before shaping the filter 32 by pressure forming, each extending downwardly from the respective four locations in the peripheral portion of the filter body 35. The downward extensions 36, as shown in FIG. 3, are formed to be inclined along the tapered surface of the pouring gate 31. [0026] The filter 32 having a configuration as described above is mounted in the pouring gate 31 by press-fitting into the pouring gate 31 such that the peripheral edge 38a of the brim section 38 is located approximately level with the runner-side opening edge (downstream end) of the pouring gate 31, as shown in FIG. 3 . Press-fitting of the filter 32 into the pouring gate 31 is performed by a worker at each casting operation. The fitting operation is performed by inserting the downward extensions 36 of the filter 32 into the pouring gate 31 from 9 the side of the cavity 28 of the lower die 22 and pressing the filter body 35 downwardly (into the pouring gate 31), with the peripheral edge 38a in contact, throughout the circumference thereof, with the inside wall of the pouring gate 31. As a result of the filter body 35 being pressed downward as described above, the annular concave section 39 and annular convex section 40 forming the brim section 38, and the base end of the hat body section 37 are elastically deformed and the filter 35 is compressed radially. That is, the filter body 35 having a bent portion acts as a spring capable of substantial elastic deformation in the radial direction. [0027] Therefore, since the filter body 35 is pressed against the inside wall of the pouring gate 31 by its own elasticity when press-fitted in the pouring gate 31, the filter 32 can be held firmly in the pouring gate 31. The spring force is remarkably large compared with conventional filters without the annular concave section 39 and annular convex section 40. The filter 32 of this embodiment is pressed upwardly by the molten metal 16 passing therethrough during casting. However, since the filter 32 is pressed against the inside wall of the pouring gate 31 by a spring force larger than that of the conventional filter, the filter is prevented from slipping off from the pouring gate 31 and entering the product part 34 even if oxides and foreign matters in the molten metal 16 are collectedby the filter 32 to increase the pressing force exerted on the filter 32. [0028] In addition, since the hat body section 37 of the filter body 35 is protruded upwardly from the brim section 38 fitted in the pouring gate 31, the upper end of the hat body section 37 is adapted to be in the solidified portion of the molten metal 16 even if the filter 35 is pressed down against the lower part of the pouring gate 31. Therefore, since the hat body section 37 is in the solidified portion without need of waiting for stoppage of pressurization until the molten metal 16 has been 10 solidified at the lower part of the pouring gate 31, time needed for one casting operation (cycle time) can be shortened. Therefore, although pressurization of the molten metal 16 must be continued until solidification spreads to a position shown in FIG. 3 by double dot and dash line A, in the casting machine 11 according to this embodiment, pressurization can be stopped some tens of seconds earlier than in the conventional casting machine. [0029] Further, since the hat body 37 is protruded upwardly and adapted to be in the solidified portion of the molten metal 16, the filter 32 can be removed from the die 13 together with the casting. That is, since there is no need of stopping the casting machine 11 only for the removal of the filter 32 from the die 13, this is combined with the shortening of the cycle time described above, providing even further improvement in productivity. [0030] The filter body 35 of the filter 32 of this embodiment is press-fitted into the pouring gate 31 such that the peripheral edge 38a of the brim section 38 is located approximately level with the runner-side opening edge of the pouring gate 31. In other words, when the filter 32 is mounted in the pouring gate 31, the filter body 35 can be positioned level with the runner-side opening edge of the pouring gate 31 using the brim section 38 as a reference. [0031] Therefore, in the filter 32, in spite of alternation of the worker who mounts the filter 32, the filter body 35 can be located at a constant position at all times such that the hat body section 37 of the filter body 35 extends into the runner 30. Therefore, since pressurization of the molten metal 16 can be stopped when the molten metal 16 is solidified in the runner 30, the pressurization of the molten metal 16 can be stopped earlier, compared with when the pressurization of the molten 11 metal 16 is stopped after solidification has reached inside the pouring gate 31. As a result, the cycle time can be shortened even further to improve production efficiency. Industrial Applicability [0032] The wire mesh filter for a casting machine according to the present invention can be applied to a filter for a low pressure casting machine for casing parts, such as cylinder heads of vehicle engines, marine engines or other general-purpose engines. 12 Claims [1] A wire mesh filter adapted to be fitted and mounted in a pouring gate of a casting machine for low pressure casting from the side of a runner, comprising: a filter body, in the shape of a brimmed hat, formed with a brim section around the entire circumference of the lower part of an upwardly convex hat body section; downward extensions extending downwardly from the peripheral portion of the filter body; and an annular concave section formed between the peripheral edge of said brim section and said hat body section. [2] The wire mesh filter for a casting machine as set forth in claim 1, wherein said filter is press-fitted in the pouring gate such that the peripheral edge of the brim section of the filter body is located approximately level with the runner-side opening edge of the pouring gate. 13 [3] The wire mesh filter for a casting machine as set forth in claim 1, wherein said filter is formed from a wire mesh of a 4 through 12-inch mesh. A filter body (35) is provided in the shape of a brimmed hat formed with a brim section (38) around the entire circumference of a hat body section (37) . Downward extensions (36) are provided extending downwardly from the peripheral portion of the filter body (35) . An annular concave section (39) is formed between the peripheral edge of the brim section 38 and the hat body section (37) .

Full Text

Specification
WIRE MESH FILTER FOR CASTING MACHINE Field of the Invention [0001]
This invention relates to a wire mesh filter mounted in a pouring gate of a casting machine for low pressure casting. Background Art [0002]
Conventionally, the cylinder head of an engine for a motorcycle, for example, has been cast using a low pressure casting process . As a casting machine for low pressure casting, a system has been disclosed, for example, in JP-A-Hei 11-57979. The casting machine disclosed in Patent Document 1 is configured such that a crucible is disposed below a die made up of a lower and an upper die, molten metal stored in the crucible is pressurized and pushed up through a stalk and a pouring gate cup so as to be supplied to the pouring gate of the lower die. [0003]
This type of casting machine has a wire mesh filter mounted in the pouring gate, as shown in FIG. 5, to prevent oxides produced in the crucible and the stalk or foreign matters in molten metal from flowing into the die together with the molten metal.
FIG. 5 is a sectional view, showing an enlarged pouring gate section of a casting machine with a conventional filter mounted therein. In FIG. 5, reference numeral 1 designates a lower die, reference numeral 2 a lower die support member, reference numeral 3 a pouring gate cup, reference numeral 4 a filter, and reference numeral 5 molten metal already solidified in the die. [0004]
The lower die 1 is formed such that its cavity 6 opens upwardly, and secured on a base plate (not shown) through the lower die support member 2. The cavity 6 is defined by the lower die and upper die (not shown) , and formed, at the lower end, with a runner 7. The runner 7 is formed in the lower die 1 such that it is recessed downwardly of a product part 8 shown in a double dot
1

and dash line in FIG. 5. A pouring gate 9 opens into the runner 7 at the bottom thereof. [0005]
The pouring gate 9 is connected to the pouring gate cup 3 held in the lower die support member 2. The pouring gate cup 3 is connected, at its lower end, to a stalk, though not shown in the figure, and in communication with the crucible through the stalk. That is, in this casting machine, molten metal passing through the stalk is pushed up to the pouring gate cup 3, and supplied into the cavity 6 (runner 7) from the pouring gate cup 3 through the pouring gate 9. [0006]
The pouring gate 9 is formed so as to gradually increase its opening diameter upwardly, and a filter 4 is mounted in the middle. The filter 4 is made from wire mesh into the shape of a bottomed cylinder by press forming. The filter 4 is formed integrally with a vertical extension 4a fitted in the pouring gate 9 and extending vertically, and a disc-like filter body 4b disposed, partitioning the pouring gate 9 in the vertical direction, at the upper end of the vertical extension 4a. The filter 4 is inserted and press-fitted in the pouring gate 9 from the side of the cavity 6 while pressed and elastically deformed by an worker.
[0007]
In this conventional casting machine, molten metal is supplied into the cavity 6 through the filter 4. When the cavity 6 is filled with the molten metal and the molten metal is solidified near the pouring gate 9, pressurization of the molten metal is stopped in the crucible. This stopping of pressurization causes unsolidified portion of the molten metal to flow down to the crucible, with solidified portion (molten metal 5) to be left in the die. In the conventional casting machine, pressurization time is set such that the filter 4 is in the solidified portion in an embedded relation with a cast product (see FIG. 5). Therefore, the filter 4 is removed from the pouring gate 9 together with the cast product when the cast
2

product is separated upwardly from the lower die 4 after casting process.
Disclosure of the invention Problem to be Solved by the Invention [0008]
In such a conventional casting machine as described above, the filter 4 is attached to the pouring gate 9 by an worker and the force applied to the filter 4 when it is press-fitted in the pouring gate 9 is different for each worker, so that there is the possibility of the filter 4 being attached in an inappropriate position. For example, when the filter 4 is mounted relatively near the runner 7 (upwardly in the figure), the force by which the filter 4 is secured inside the pouring gate 9 becomes smaller. In this case, there is the possibility of the filter 4 being pressed by molten metal during casting, to thereby slip off from the pouring gate 9 toward the runner 7 and enters the region of the product part 8. If the filter 4 enters the region of the product part 8, the cast product becomes defective. [0009]
On the other hand, when the filter 4 is mounted at a position relatively near the pouring cup 3 (downwardly in the figure) , there is a possibility of failing to take the filter 4 into the solidified portion 5 of molten metal. In this case, the filter 4 remains in the pouring gate 9 after separation of the cast product from the die. Therefore, the casting machine must be stopped to remove the filter 4 before the next casting, preventing continuous operation of the casting machine. In the conventional casting machine, to avoid such a trouble, molten metal is pressurized until solidification of the molten metal reaches the bottom of the pouring gate 9, for the filter 4 not to remain in the pouring gate 9. Therefore, the use of the conventional wire mesh filter for a casting machine raises a problem that time needed for one casting operation (cycle time) is prolonged.
[0010]
3

In order to solve the foregoing problems, an object of this invention is to provide a wire mesh filter for a casting machine in which slipping off of a filter from a pouring gate by the pressure of molten metal is prevented and the filter is allowed to be taken into the cast product even if the pressurization time of the molten metal is short. Means for Solving the Problem [0011]
To achieve the foregoing object, this invention is directed to a wire mesh filter adapted to be fitted and mounted in a pouring gate of a casting machine for low pressure casting from the side of a runner, comprising: a filter body, in the shape of a brimmed hat, formed with a brim section around the entire circumference of the lower part of an upwardly convex hat body section; downward extensions extending downwardly from the peripheral portion of the filter body; and an annular concave section formed between the peripheral edge of said brim section and said hat body section. Effects of the Invention [0012]
According to the invention, since the filter body having a bent portion acts as a spring capable of substantial elastic deformation in the radial direction, the spring force of the filter body in press contact with the inside wall of the pouring gate can be increased while the filter body is pressed in the pouring gate.
Therefore, since the filter can be held firmly in the pouring gate, slipping off of the filter from the pouring gate by the pressure of molten metal during casting can be prevented reliably, improving the yield. [0013]
In addition, since the hat body section of the filter body is protruded upwardly from the brim section fitted in the pouring gate, the hat body section can be adapted to extend at the upper end into the solidified portion of molten metal even when the filter body is located in the pouring gate at a relatively lower
4

part. Therefore, since part (hat) of the filter is in the solidified portion without need of waiting until the molten metal is solidified up to the region of the lower part of the pouring gate, time needed for one casting operation (cycle time) can be shortened. In addition, the filter can be removed reliably from the die together with a casting, preventing stopping an operation of the casting machine only for the removal of the filter from the die. Therefore, this is combined with shortening the cycle time described above, providing further improvement in productivity. [0014]
According to the invention of Claim 2, the filter body can be positioned in the pouring gate at the runner-side opening edge using the brim section of the filter body as a reference. According to this invention, therefore, the filter body can be located at a constant position at all times such that the hat body section of the filter body extends into the runner, in spite of alternation of an worker who mounts the filter. Therefore, since pressurization of molten metal can be stopped when the molten metal is solidified in the runner, the timing at which pressurization of molten metal is stopped, can be advanced, compared with the timing at which the pressurization of the molten metal is stopped after solidification of the molten metal has reached the pouring gate. As a result, the cycle time can be shortened even further to improve production efficiency. [0015]
According to the invention of Claim 3, resistance produced when the molten metal passes through the wire mesh filter can be minimized, and foreign matters in the molten metal can be reliably removed with the wire mesh filter. Brief Description of Drawings [0016]
FIG. 1 is a sectional view of a casting machine for low pressure casting with a filter according to this invention. FIG. 2 is a plan view of a lower die. Fig. 3 is an enlarged sectional view, showing an essential
5

part.
FIG. 4 is a perspective view of the filter.
FIG. 5 is an enlarged sectional view, showing a pouring gate section of a casting machine having a conventional filter mounted thereon.
Best Mode for Carrying Out the Invention [0017]
Now, an embodiment of this invention is described with reference to the drawings.
In FIGs . 1 through 4, designated by reference numeral 11 is a casting machine for low pressure casting of this embodiment. The casting machine 11 is one for casting a cylinder head (not shown) of an engine for a motorcycle by low pressure casting, and as has been well known, a die 13 is disposed above a furnace 12.
[0018]
The furnace 12 is composed of a body 14 formed in the shape of an upwardly opening box, a cover 15 for closing the upper opening section of the body 14, a crucible 17 for storing molten metal 16, a stalk 18 attached to the cover 15 and submerged at the lower end in the molten metal 16, and others. The body 14 of the furnace 12 contains a heater (not shown) for heating the molten metal 16 in the crucible 17 at a given temperature and is connected to a pressurization device (not shown). The pressurization device has a function of supplying inert gas into the body 14 during casting to pressurize the upper surface of the molten metal 16 and push up the molten metal 16 into the stalk 18, and a gas pipe (not shown) is connected to a connection port 14a formed in the body 14.
[0019]
Casting by the casting machine 11 is performed, as in the conventional casting machine, by pressurizing the interior of the body 14 of the furnace 12 by the pressurization device, with the die 13 clamped. During casting, the molten metal 16 is fed upward from the crucible 17 through the stalk 18 and supplied into the dies 13 located above them.
6

The dies 13 is composed of an upper die 21 and a lower die 22 and supported by a driving device 23. The upper die 21 is formed with a downwardly opening cavity 24, and attached to a platen 25 of the driving device 23. The platen 25 is supported on a base plate 26 of the driving device 23 through tie bars 27 for up and down movement and adapted to be moved vertically by a vertical feed motor (not shown).
[0020] The lower die 22 is formed with an upwardly opening cavity
28, and secured on the base plate 26 through a support member
29. The lower die 22 and upper die 21 are each provided with
a heater (not shown) for preheating the die to a casting
temperature, and a water-cooling type cooling device (not shown)
for keeping the die temperature constant during casting.
In the bottom of the cavity 28 of the lower die 22 is formed a runner 30 extending from one side of the cavity 28 to the other side and a pouring gate 31 is formed extending downwardly from the bottom of the runner 30, as shown in FIG. 2 and FIG. 3.
[0021]
The pouring gate 31 formed in the bottom of the lower die 22 has an oval shape, as viewed from above in FIG. 2 . The diameter of the pouring gate 31 is gradually increased toward the upper end to form a draft as shown in FIG. 3. In the opening of the pouring gate 31 at the upper end is mounted a filter 32 (described later). To the lower end of the pouring gate 31 is connected the upper end of a pouring gate cup 33 provided in the lower die support member 29. The pouring gate cup 33, as shown in FIG. 1, penetrates the support member 29 in the vertical direction. The molten metal 16 is supplied into the pouring gate cup 33 from the upper end of the stalk 18 in abutment against the lower surface of the support member 29. That is, during casting, the molten metal 16 flows into the pouring gate 31 from the stalk 18 through the pouring gate cup 33, then into the runner 30 from the pouring gate 31 through the filter 32, to be supplied to cavities 24, 28.
[0022]
7

The molten metal 16 which has filled up the cavities 24, 28,
begins solidifying at the product part 34 (see FIG. 3) within
the cavities 24, 28. Solidification of the molten metal 16
advances with time from inside the runner 30 to the pouring gate
31. The casting machine 11 of this embodiment stops
pressurization by the pressurization device when
solidification advances up to a region near the boundary between
the runner 30 and pouring gate 31, causing an unsolidified
portion of the molten metal 16 to flow down to the crucible 17.
In this embodiment, the timing at which the pressurization is
stopped, is determined based on the temperature of the molten
metal 16 near the boundary detected by a temperature sensor (not
shown) mounted on the lower die 22.
[0023]
The filter 32, as shown in FIG. 3 and FIG. 4, includes a filter body 35 in the shape of a brimmed hat, downward extensions 36 extending downwardly from the periphery of the filter body 35, and an annular concave section 39 (described later). The filter 32 of this embodiment is manufactured from a zinc-plated wire mesh, made of steel, being shaped by a pressurization-forming device (not shown). Although numerous auxiliary lines are depicted in FIG. 4 for easy understanding of the shape of the filter 32, the mesh of the filter 32 is formed from wire mesh woven in the directions different from those of the auxiliary lines. The experiment showed that using a wire mesh of a 4 through 12-inch mesh for the filter 32 can minimize the resistance produced when the molten metal passes therethrough and assure removal of foreign matters in the molten metal. Specifically, it was revealed that using a wire mesh of an 8-inch mesh for the filter 32 ensures the most effective removal of foreign matters.
[0024]
The filter body 35 has a hat body section 37 formed in the shape of an upwardly convex, bottomed cylinder, and a brim section 38 formed continuously around the entire circumference of the lower part of the hat body section 37, and has the shape
8

of a brimmed hat as a whole.
The brim section 38 has the peripheral edge 38a connected to the downward extensions 36. The annular concave section 39 described above is formed between the peripheral edge 38a and the hat body section 37. The annular concave section 39 is open upward.
[0025]
In this embodiment, the peripheral edge 38a of the brim section 38 is curved gradually downwardly toward the outer end in the radial direction and smoothly connected to the upper end of the downward extensions 36. As described above, since the brim section 38 is curved at the peripheral edge 38a and the annular concave section 39 is located radially inwardly of the peripheral edge 38a, the brim section 38 is formed in the shape of a letter S in section by the annular concave section 39 located on the inside circumferential side and an annular convex section 40 located on the outside circumferential side. The brim section 38 has an outside diameter a little larger than the inside diameter of the runner-side opening edge of the pouring gate 31.
The downward extensions 36 are portions corresponding to the four corners of a wire mesh before shaping the filter 32 by pressure forming, each extending downwardly from the respective four locations in the peripheral portion of the filter body 35. The downward extensions 36, as shown in FIG. 3, are formed to be inclined along the tapered surface of the pouring gate 31.
[0026]
The filter 32 having a configuration as described above is mounted in the pouring gate 31 by press-fitting into the pouring gate 31 such that the peripheral edge 38a of the brim section 38 is located approximately level with the runner-side opening edge (downstream end) of the pouring gate 31, as shown in FIG. 3 . Press-fitting of the filter 32 into the pouring gate 31 is performed by a worker at each casting operation. The fitting operation is performed by inserting the downward extensions 36 of the filter 32 into the pouring gate 31 from
9

the side of the cavity 28 of the lower die 22 and pressing the filter body 35 downwardly (into the pouring gate 31), with the peripheral edge 38a in contact, throughout the circumference thereof, with the inside wall of the pouring gate 31. As a result of the filter body 35 being pressed downward as described above, the annular concave section 39 and annular convex section 40 forming the brim section 38, and the base end of the hat body section 37 are elastically deformed and the filter 35 is compressed radially. That is, the filter body 35 having a bent portion acts as a spring capable of substantial elastic deformation in the radial direction. [0027]
Therefore, since the filter body 35 is pressed against the inside wall of the pouring gate 31 by its own elasticity when press-fitted in the pouring gate 31, the filter 32 can be held firmly in the pouring gate 31. The spring force is remarkably large compared with conventional filters without the annular concave section 39 and annular convex section 40.
The filter 32 of this embodiment is pressed upwardly by the molten metal 16 passing therethrough during casting. However, since the filter 32 is pressed against the inside wall of the pouring gate 31 by a spring force larger than that of the conventional filter, the filter is prevented from slipping off from the pouring gate 31 and entering the product part 34 even if oxides and foreign matters in the molten metal 16 are collectedby the filter 32 to increase the pressing force exerted on the filter 32. [0028]
In addition, since the hat body section 37 of the filter body 35 is protruded upwardly from the brim section 38 fitted in the pouring gate 31, the upper end of the hat body section 37 is adapted to be in the solidified portion of the molten metal 16 even if the filter 35 is pressed down against the lower part of the pouring gate 31. Therefore, since the hat body section 37 is in the solidified portion without need of waiting for stoppage of pressurization until the molten metal 16 has been
10

solidified at the lower part of the pouring gate 31, time needed for one casting operation (cycle time) can be shortened. Therefore, although pressurization of the molten metal 16 must be continued until solidification spreads to a position shown in FIG. 3 by double dot and dash line A, in the casting machine 11 according to this embodiment, pressurization can be stopped some tens of seconds earlier than in the conventional casting machine.
[0029]
Further, since the hat body 37 is protruded upwardly and adapted to be in the solidified portion of the molten metal 16, the filter 32 can be removed from the die 13 together with the casting. That is, since there is no need of stopping the casting machine 11 only for the removal of the filter 32 from the die 13, this is combined with the shortening of the cycle time described above, providing even further improvement in productivity.
[0030]
The filter body 35 of the filter 32 of this embodiment is press-fitted into the pouring gate 31 such that the peripheral edge 38a of the brim section 38 is located approximately level with the runner-side opening edge of the pouring gate 31. In other words, when the filter 32 is mounted in the pouring gate 31, the filter body 35 can be positioned level with the runner-side opening edge of the pouring gate 31 using the brim section 38 as a reference.
[0031]
Therefore, in the filter 32, in spite of alternation of the worker who mounts the filter 32, the filter body 35 can be located at a constant position at all times such that the hat body section 37 of the filter body 35 extends into the runner 30.
Therefore, since pressurization of the molten metal 16 can be stopped when the molten metal 16 is solidified in the runner 30, the pressurization of the molten metal 16 can be stopped earlier, compared with when the pressurization of the molten
11

metal 16 is stopped after solidification has reached inside the pouring gate 31. As a result, the cycle time can be shortened even further to improve production efficiency. Industrial Applicability
[0032]
The wire mesh filter for a casting machine according to the present invention can be applied to a filter for a low pressure casting machine for casing parts, such as cylinder heads of vehicle engines, marine engines or other general-purpose engines.
12

Claims
[1] A wire mesh filter adapted to be fitted and mounted in a pouring gate of a casting machine for low pressure casting from the side of a runner, comprising: a filter body, in the shape of a brimmed hat, formed with a brim section around the entire circumference of the lower part of an upwardly convex hat body section; downward extensions extending downwardly from the peripheral portion of the filter body; and an annular concave section formed between the peripheral edge of said brim section and said hat body section.
[2] The wire mesh filter for a casting machine as set forth in claim 1, wherein said filter is press-fitted in the pouring gate such that the peripheral edge of the brim section of the filter body is located approximately level with the runner-side opening edge of the pouring gate.
13
[3] The wire mesh filter for a casting machine as set forth in claim 1, wherein said filter is formed from a wire mesh of a 4 through 12-inch mesh.

A filter body (35) is provided in the shape of a brimmed hat formed with a brim section (38) around the entire circumference of a hat body section (37) . Downward extensions (36) are provided extending downwardly from the peripheral portion of the filter body (35) . An annular concave section (39) is formed between the peripheral edge of the brim section 38 and the hat body section (37) .

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Patent Number

253712

Indian Patent Application Number

1950/KOLNP/2006

PG Journal Number

33/2012

Publication Date

17-Aug-2012

Grant Date

14-Aug-2012

Date of Filing

12-Jul-2006

Name of Patentee

YAMAHA HATSUDOKI KABUSHIKI KAISHA

Applicant Address

2500 SHINGAI, IWATA-SHI,SHI SHIZUOKA 4388501

Inventors:

#	Inventor's Name	Inventor's Address
1	HIROSHI YOSHII	C/O YAMHA HATSUDOKI KABUSHIKI KAISHA 2500 SHINGAI, IWATA-SHI SHIZUOKA 4388501
2	TAKASHI ODA	2500 SHINGAI, IWATA-SHI SHIZUOKA 4388501

PCT International Classification Number

B22D18/04; B22C9/08

PCT International Application Number

PCT/JP 05/000683

PCT International Filing date

2005-01-20

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2004-012869	2004-01-21	Japan