A casting device for a mine car wheel hub

Abstract

The present invention discloses a casting device for a mine wheel hub, belonging to the technical field of metal casting, including a lower mold, an upper mold, a middle mold and a partition mold. A casting forming cavity is formed between the lower mold, the upper mold, the middle mold and the partition mold. The lower mold includes a bottom support and a pouring shell, and the pouring shell is fixed at the central position inside the bottom support. In the present invention, the pouring shell guides the molten metal to enter from a large-range pouring groove in the bottom layer area of the casting forming cavity, and the exposed air vents discharge the accumulated gas generated by the molten metal entering from below upwards. After the molten metal fills the casting forming cavity, the profiling sand core is pushed by the molten metal to rotate inside the upper mold, disturbing the molten metal in the upper layer area of the casting forming cavity to adjust the state of the molten metal, and at the same time squeezing and treating the accumulated gas dissipated in the upper half area of the casting forming cavity, treating the non-dissipated gas and gas film in each area of the metal mold, and eliminating the exposed air holes on the surface of the mine wheel hub casting.

Description

Technical Field

[0001] The invention relates to the technical field of metal casting, and in particular to a casting device for a mine wheel hub. Background Art

[0002] The wheel hub of the mine wheel is mass-produced by metal casting. The molten metal is injected into the metal mold that matches the shape of the mine wheel hub through the pouring gate. The molten metal gradually fills the molding cavity inside the mold from bottom to top. The molten metal is cooled and shaped in the molding cavity to form a mine wheel hub casting. The high-temperature molten metal is directly poured into the metal mold. The high-temperature molten metal continuously flushes the inner wall of the metal mold in the molding cavity, so that the gas generated by the molten metal does not have time to overflow from the metal mold, resulting in exposed pores on the surface of the mine wheel hub casting. The invention patent with announcement number CN104907535B discloses an aluminum alloy wheel hub casting mold, which transfers bubbles through exhaust lines and air collecting blind holes to reduce pores on the surface of the molded casting. In addition, there are also measures in the prior art to increase the exhaust channel to strengthen the air entrainment during the pouring process and eliminate the pores in the end face area of the hub casting. However, during the molten metal pouring process, the gas generated by the first pouring of the molten metal has a long time to escape, while the gas generated by the later pouring of the molten metal has insufficient time to escape, so that the later generated gas is still in the upper area of the molding cavity, and the accumulated gas and the un-escaped gas in the upper area of the molding cavity cannot be effectively treated, so that the gas accumulates in the ribs and outer edge of the upper half of the wheel hub casting, and the accumulated gas and the generated gas film are easily dispersed into the surface shell of the mine wheel hub casting that has not been fully solidified, thereby failing to effectively eliminate the exposed pores on the surface of the mine wheel hub casting, affecting the casting effect of the mine wheel hub. Summary of the invention

[0003] In order to overcome the above-mentioned defects of the prior art, the present invention provides a casting device for a mine wheel hub, which guides the molten metal to enter from a large-scale pouring groove in the bottom area of the casting molding cavity by arranging a pouring shell, and the exposed air permeable groove discharges the accumulated gas generated by the molten metal entering from the bottom upward, thereby expanding the runner and the exhaust channel, and at the same time increasing the auxiliary exhaust channel. After the molten metal fills the casting molding cavity, part of the poured molten metal is diverted to the temporary storage space on the outer edge sand core, and the contoured sand core is pushed by the molten metal to rotate on the inner side of the upper mold, thereby disturbing the molten metal in the upper area of the casting molding cavity to adjust the state of the molten metal, and at the same time squeezing and processing the accumulated gas dissipated in the upper half of the casting molding cavity, processing the non-dissipated gas and gas film in various areas of the metal casting mold, and eliminating the exposed pores on the surface of the mine wheel hub casting, so as to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A casting device for a mine car hub, comprising a lower mold, an upper mold, a middle mold and a partition mold. A casting forming cavity is formed between the lower mold, the upper mold, the middle mold and the partition mold. The lower mold includes a bottom support and a pouring shell. The pouring shell is fixed at the central position inside the bottom support. The upper mold is closed on the top of the bottom support through the pouring shell. Pouring grooves communicating with each other are formed in the bottom support and the pouring shell. The middle mold includes an outer edge sand core, a guiding ring, a profiling sand core, a pressing-down sand core and splicing blocks. The outer edge sand core and the guiding ring are positioned on the inner wall of the upper mold from top to bottom through the pressing-down sand core. The profiling sand core is closed inside the outer edge sand core, the guiding ring and the pressing-down sand core and clamps and positions the four splicing blocks inside the upper mold. The splicing blocks are separated from the inner side wall of the profiling sand core to discharge upward the accumulated gas generated by the molten metal entering the inside of the casting forming cavity from below. The profiling sand core is pushed by the molten metal to rotate inside the upper mold to process the accumulated gas dissipated in the upper half area of the casting forming cavity. The number of the partition molds is six, and the six partition molds are fixedly arranged in a ring on the inner side wall of the bottom support.

[0006] Further, the upper mold is snap-fitted and connected to the outside of the pouring shell, and the bottom of the upper mold is clamped on the top of the bottom support.

[0007] Further, the outer edge sand core is fixedly connected to the bottom of the pressing-down sand core, the guiding ring is fixedly connected to the bottom of the outer edge sand core, the profiling sand core is clamped on the inner side walls of the outer edge sand core, the guiding ring and the pressing-down sand core. The bottom of the guiding ring is clamped on the top of the bottom support, and the top of the pressing-down sand core is clamped on the inner wall of the upper mold.

[0008] Further, a docking block is fixedly connected to the bottom edge part of the outer side wall of the profiling sand core. The docking block is slidably connected inside the guiding ring. A baffle is fixedly connected inside the outer edge sand core. The baffle is located behind the docking block, and the bottom end of the baffle is fixedly connected inside the guiding ring.

[0009] Further, two connecting blocks are fixedly connected to the outer side wall of the splicing block. The connecting blocks are snap-fitted and connected inside the profiling sand core.

[0010] Further, four air-permeable grooves corresponding to the splicing blocks are formed in the profiling sand core. The splicing blocks are snap-fitted and connected to the inner side wall of the profiling sand core.

[0011] Further, four perforated air-permeable blocks corresponding to the splicing blocks are fixedly connected inside the upper mold. The perforated air-permeable blocks are snap-fitted and connected inside the pressing-down sand core. The bottom ends of the perforated air-permeable blocks communicate with the corresponding air-permeable grooves.

[0012] Furthermore, a shunt pipe is fixedly connected to the top of the upper mold, the input end of the shunt pipe is plugged into the casting shell, a temporary storage space corresponding to the shunt pipe is opened inside the outer edge sand core, and the output end of the shunt pipe is plugged into the temporary storage space.

[0013] Furthermore, the top of the casting shell is located above the upper mold, and a clearance groove is provided on the casting shell, and the clearance groove is connected to the pouring groove to ensure that the molten metal is poured into the casting molding cavity.

[0014] Furthermore, a column is fixedly connected inside the partition mold, the top end of the column is closely attached to the inner wall of the contoured sand core, and the bottom end of the column is closely attached to the inner wall of the base.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention provides a combined lower mold, an upper mold, a middle mold and a plurality of partition molds, and after the molds are closed in sequence, a casting molding cavity adapted to the shape of a mine wheel hub is formed, the molten metal is guided by a pouring shell, and enters the inside of the casting molding cavity through a large-scale pouring groove in the bottom area of the casting molding cavity, the splicing block is separated from the inner side wall of the profiling sand core, and the air permeable groove at the corresponding position is exposed to discharge upward the accumulated gas generated by the molten metal entering from the bottom, thereby expanding the runner and the exhaust channel, and at the same time increasing the auxiliary exhaust channel, reducing the accumulation of gas in the edge area of each layer of the casting molding cavity, and the molten metal is discharged in the casting molding cavity. The rise in the cavity can push the splicing block to return to the contoured sand core. After the molten metal fills the casting molding cavity, part of the poured molten metal is diverted to the temporary storage space on the outer edge sand core. The contoured sand core is pushed by the molten metal to rotate on the inner side of the upper mold, which can disturb the molten metal in the upper area of the casting molding cavity to adjust the state of the molten metal, and at the same time squeeze and process the accumulated gas dissipated in the upper half of the casting molding cavity, so as to achieve the effect of processing the undissipated gas and gas film in various areas of the metal casting mold, and eliminate the exposed pores on the surface of the mine wheel hub casting, thereby improving the casting effect and efficiency of the mine wheel hub. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution in the embodiment, the drawings in the embodiment are briefly introduced below.

[0018] Figure 1 It is a product schematic diagram of an existing mine wheel hub;

[0019] Figure 2 It is a structural schematic diagram of the present invention;

[0020] Figure 3 It is a schematic cross-sectional structure diagram of the present invention;

[0021] Figure 4 It is a schematic diagram of the cross-sectional structure of the present invention in the mold closing state;

[0022] Figure 5 This is a schematic structural view of the decomposition state of the present invention.

[0023] In the figure: 1, lower mold; 11, bottom support; 12, casting shell; 121, relief groove; 13, pouring groove; 2, upper mold; 21, perforated air-permeable block; 22, shunt pipe; 3, middle mold; 31, outer edge sand core; 311, baffle; 32, guiding ring; 33, profiling sand core; 331, docking block; 332, air-permeable groove; 34, downward pressing sand core; 35, splicing block; 351, connecting block; 36, temporary storage space; 4, partition mold; 41, column; 5, casting forming cavity. Specific embodiments

[0024] The following combines the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Regarding the specific mechanical structure of the present invention, it will be clearly presented in the following detailed description of the structure. The structural contents mentioned in the following embodiments are all referenced to the accompanying drawings of the specification. Figures 1 to 5 In the detailed description of the structure, it will be clearly presented. The structural contents mentioned in the following embodiments are all referenced to the accompanying drawings of the specification.

[0025] Please refer to Figures 1 - 5 , in the embodiments of the present invention, a casting device for a mine wheel hub includes a lower mold 1, an upper mold 2, a middle mold 3, and a partition mold 4. A casting forming cavity 5 is formed between the lower mold 1, the upper mold 2, the middle mold 3, and the partition mold 4. The lower mold 1 includes a bottom support 11 and a casting shell 12. The casting shell 12 is fixed at the central position inside the bottom support 11. The upper mold 2 is closed on the top of the bottom support 11 through the casting shell 12. Pouring grooves 13 communicating with each other are provided on the bottom support 11 and the casting shell 12. The middle mold 3 includes an outer edge sand core 31, a guiding ring 32, a profiling sand core 33, a downward pressing sand core 34, and a splicing block 35. The outer edge sand core 31 and the guiding ring 32 are positioned on the inner wall of the upper mold 2 from top to bottom through the downward pressing sand core 34. The profiling sand core 33 is closed inside the outer edge sand core 31, the guiding ring 32, and the downward pressing sand core 34, and four splicing blocks 35 are clamped and positioned inside the upper mold 2. The splicing block 35 is separated from the inner side wall of the profiling sand core 33 to discharge the accumulated gas generated by the molten metal entering the inside of the casting forming cavity 5 from below. The profiling sand core 33 is pushed by the molten metal to rotate inside the upper mold 2 to process the accumulated gas dissipated in the upper half area of the casting forming cavity 5. The number of partition molds 4 is six, and the six partition molds 4 are fixedly arranged in a ring on the inner side wall of the bottom support 11.

[0026] The middle mold 3 for mold clamping is inside the upper mold 2. Six partition molds 4 are arranged equidistantly in a ring inside the lower mold 1. The upper mold 2 clamps the middle mold 3 together and closes the mold to the top of the lower mold 1, so that the lower mold 1, the upper mold 2, the middle mold 3 and the six partition molds 4 cooperate to form a metal mold adapted to the shape of the mine wheel hub. A casting cavity 5 matching the shape of the mine wheel hub is formed between the lower mold 1, the upper mold 2, the middle mold 3 and the partition mold 4. The molten metal enters the inside of the casting cavity 5 to cast the mine wheel hub inside the casting cavity 5.

[0027] The lower mold 1 is composed of a bottom tray 11 and a pouring shell 12. The pouring shell 12 is fixedly connected to the inner center position of the bottom tray 11, so that the pouring shell 12 extends upward to the outside of the bottom tray 11. When the upper mold 2 approaches the lower mold 1 from above, the upper mold 2 can be clamped to the outside of the pouring shell 12 and move vertically downward along the surface of the pouring shell 12, so that the bottom of the upper mold 2 is tightly clamped on the top of the bottom tray 11 to effectively complete the fixed-point mold clamping operation of the upper mold 2 to the top of the lower mold 1. After the upper mold 2 is clamped to the top of the lower mold 1, the top of the pouring shell 12 is located above the upper mold 2, so that the molten metal can be poured in from the gate at the top of the pouring shell 12. Pouring grooves 13 communicating with each other are provided on the bottom tray 11 and the pouring shell 12. Guided by the pouring shell 12, the molten metal can enter the inside of the casting cavity 5 through the large-range communicating pouring grooves 13 to effectively guide and pour the molten metal into the casting cavity 5. A relief groove 121 is provided on the pouring shell 12, and the relief groove 121 communicates with the pouring groove 13 to ensure that the molten metal is smoothly poured into the casting cavity 5. A column 41 is fixedly connected inside the partition mold 4. The top of the column 41 is closely attached to the inner side wall of the profiling core 33, and the bottom of the column 41 is closely attached to the inner side wall of the bottom tray 11, which can effectively position and connect the partition mold 4 at a specified position inside the lower mold 1.

[0028] The middle mold 3 is composed of an outer-edge core 31, a guiding ring 32, a profiling core 33, a lower pressing core 34, and splicing blocks 35. The outer-edge core 31 is fixedly connected to the bottom of the lower pressing core 34. The guiding ring 32 is fixedly connected to the bottom of the outer-edge core 31. The profiling core 33 is clamped on the inner side walls of the outer-edge core 31, the guiding ring 32, and the lower pressing core 34, positioning the profiling core 33 inside the outer-edge core 31, the guiding ring 32, and the lower pressing core 34. The top of the lower pressing core 34 is clamped on the inner wall of the upper mold 2, facilitating the combination of the middle mold 3 inside the upper mold 2. The bottom of the guiding ring 32 is clamped on the top of the bottom support 11, stably clamping the middle mold 3 together with the upper mold 2 on the top of the lower mold 1. The number of splicing blocks 35 is four. Two connecting blocks 351 are fixedly connected to the outer side wall of the splicing block 35. The connecting blocks 351 are snap-connected inside the profiling core 33, capable of clamping and positioning the four splicing blocks 35 inside the profiling core 33, to position the four splicing blocks 35 inside the upper mold 2. Four air-permeable grooves 332 corresponding to the splicing blocks 35 are provided on the profiling core 33. Four perforated air-permeable blocks 21 corresponding to the splicing blocks 35 are fixedly connected inside the upper mold 2. The perforated air-permeable blocks 21 are snap-connected inside the lower pressing core 34. The bottom end of the perforated air-permeable block 21 communicates with the corresponding air-permeable groove 332. Through the air-permeable groove 332 and the perforated air-permeable block 21, the gas inside the casting forming cavity 5 can be assisted in discharging. On the inner side wall of the profiling core 33, there is a profiling accommodating groove corresponding to the splicing block 35. The splicing block 35 is pushed by the rising molten metal and can be clamped upward inside the corresponding profiling accommodating groove on the inner side wall of the profiling core 33, effectively restoring and matching the casting forming cavity 5 of the ore wheel hub casting, ensuring the forming of the ore wheel hub casting inside the casting forming cavity 5.

[0029] A shunt pipe 22 is fixedly connected to the top of the upper mold 2. The input end of the shunt pipe 22 is inserted inside the pouring shell 12. A temporary storage space 36 corresponding to the shunt pipe 22 is provided inside the outer-edge core 31. The output end of the shunt pipe 22 is inserted inside the temporary storage space 36, enabling part of the molten metal to be guided into the temporary storage space 36 on the outer-edge core 31 through the shunt pipe 22. A docking block 331 is fixedly connected to the bottom edge part of the outer side wall of the profiling core 33. The docking block 331 is slidably connected inside the guiding ring 32. A baffle 311 is fixedly connected inside the outer-edge core 31. The baffle 311 is located behind the docking block 331. The bottom end of the baffle 311 is fixedly connected inside the guiding ring 32. The molten metal enters the temporary storage space 36 and gradually fills the temporary storage space 36. The molten metal impacts the docking block 331, enabling the docking block 331 to move along the inner wall of the guiding ring 32 inside the guiding ring 32, causing the profiling core 33 to rotate along the inner side walls of the outer-edge core 31, the guiding ring 32, and the lower pressing core 34, realizing the movement of the profiling core 33.

[0030] The combined lower die 1, upper die 2, middle die 3 and six partition dies 4 form a casting cavity 5 adapted to the shape of the mine wheel hub after being closed in sequence. The molten metal is guided by the pouring shell 12 and enters the interior of the casting cavity 5 through a large-range pouring groove 13 located in the bottom layer area of the casting cavity 5, and gradually rises inside the casting cavity 5 to form the mine wheel hub casting through the casting cavity 5. The splicing block 35 is separated from the inner side wall of the profiling core 33, exposing the air vents 332 at the corresponding positions to discharge the accumulated gas generated by the molten metal entering from below upwards, expanding the runner and the exhaust passage, and at the same time increasing the auxiliary exhaust passage, which can improve the dissipation effect and efficiency of the gas to the outside and reduce the accumulation of gas in the edge areas of each layer of the casting cavity 5. The rising of the molten metal in the casting cavity 5 can push the splicing block 35 back to the profiling core 33. After the casting cavity 5 is filled with the molten metal, a part of the poured molten metal is diverted into the temporary storage space 36 on the outer edge core 31. The profiling core 33 is pushed by the molten metal to rotate inside the upper die 2, which can disturb the molten metal in the upper layer area of the casting cavity 5 to adjust the state of the molten metal and improve the mixing effect of the molten metal entering successively. At the same time, the profiling core 33 can squeeze and process the accumulated gas dissipated in the upper half area of the casting cavity 5, avoiding the formation of a gas film between the upper half of the mine wheel hub casting and the metal mold due to the failure of the gas to dissipate, achieving the effect of processing the un-dissipated gas in each area of the metal mold and eliminating the exposed air holes on the surface of the mine wheel hub casting, and improving the casting effect and casting efficiency of the mine wheel hub.

[0031] The working principle of the present invention is as follows: The lower die 1, upper die 2, middle die 3 and six partition dies 4 are closed in sequence to form a metal mold adapted to the shape of the mine wheel hub. A casting cavity 5 adapted to the shape of the mine wheel hub is formed inside the metal mold. The molten metal is poured into the pouring gate at the top of the pouring shell 12, and the pouring shell 12 guides the molten metal to enter the interior of the casting cavity 5 downward through a large-range pouring groove 13 located in the bottom layer area of the casting cavity 5. The molten metal gradually rises inside the casting cavity 5, and the accumulated gas generated by the molten metal inside the casting cavity 5 is discharged upward from the exposed air vents 332 to assist the exhaust of the accumulated gas. The rising of the molten metal in the casting cavity 5 pushes the splicing block 35 back to the profiling core 33. After the casting cavity 5 is filled with the molten metal, a part of the poured molten metal is diverted into the temporary storage space 36 on the outer edge core 31. The profiling core 33 is pushed by the molten metal to rotate inside the upper die 2, disturbing the molten metal in the upper layer area of the casting cavity 5 to adjust the mixing state of the molten metal. At the same time, the profiling core 33 squeezes and processes the accumulated gas dissipated in the upper half area of the casting cavity 5, processes the un-dissipated gas and the gas film formed due to the failure of the gas to dissipate, and eliminates the exposed air holes on the surface of the mine wheel hub casting.

[0032] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A casting device for a mine wheel hub, characterized in that, It includes a lower mold (1), an upper mold (2), a middle mold (3) and a partition mold (4). A casting forming cavity (5) is formed among the lower mold (1), the upper mold (2), the middle mold (3) and the partition mold (4). The lower mold (1) includes a bottom support (11) and a pouring shell (12). The pouring shell (12) is fixed at the central position inside the bottom support (11). The upper mold (2) is clamped on the top of the bottom support (11) through the pouring shell (12). Pouring grooves (13) which are communicated with each other are formed on the bottom support (11) and the pouring shell (12). The middle mold (3) includes an outer edge core (31), a guiding ring (32), a profiling core (33), a pressing-down core (34) and a splicing block (35). The outer edge core (31) and the guiding ring (32) are positioned on the inner wall of the upper mold (2) from top to bottom through the pressing-down core (34). The profiling core (33) is clamped inside the outer edge core (31), the guiding ring (32) and the pressing-down core (34), and four splicing blocks (35) are clamped and positioned inside the upper mold (2). The splicing block (35) is separated from the inner side wall of the profiling core (33) to discharge upward the accumulated gas generated by the molten metal entering the inside of the casting forming cavity (5) from below. The profiling core (33) is pushed by the molten metal to rotate inside the upper mold (2) to handle the accumulated gas dissipated in the upper half area of the casting forming cavity (5). The number of the partition molds (4) is six, and the six partition molds (4) are fixedly arranged in a ring on the inner side wall of the bottom support (11).

2. The casting device for a mine wheel hub according to claim 1, characterized in that, The upper mold (2) is clamped and connected to the outside of the pouring shell (12), and the bottom of the upper mold (2) is clamped on the top of the bottom support (11).

3. The casting device for a mine wheel hub according to claim 1, characterized in that, The outer edge core (31) is fixedly connected to the bottom of the pressing-down core (34), the guiding ring (32) is fixedly connected to the bottom of the outer edge core (31). The profiling core (33) is clamped on the inner side walls of the outer edge core (31), the guiding ring (32) and the pressing-down core (34). The bottom of the guiding ring (32) is clamped on the top of the bottom support (11), and the top of the pressing-down core (34) is clamped on the inner wall of the upper mold (2).

4. A casting device for a mine wheel hub according to claim 1, characterized in that, A butt joint block (331) is fixedly connected to the bottom edge part of the outer side wall of the profiling core (33). The butt joint block (331) is slidably connected inside the guiding ring (32). A baffle (311) is fixedly connected inside the outer edge core (31). The baffle (311) is located behind the butt joint block (331), and the bottom end of the baffle (311) is fixedly connected inside the guiding ring (32).

5. The casting device for a mine wheel hub according to claim 1, characterized in that, Two connecting blocks (351) are fixedly connected to the outer side wall of the splicing block (35). The connecting blocks (351) are clamped and connected inside the profiling core (33).

6. The casting device for a mine wheel hub according to claim 1, characterized in that, Four air vent grooves (332) corresponding to the splicing blocks (35) are formed on the profiling core (33). The splicing blocks (35) are clamped and connected to the inner side wall of the profiling core (33).

7. The casting device for a mine wheel hub according to claim 6, characterized in that, Four perforated air-permeable blocks (21) corresponding to the splicing blocks (35) are fixedly connected inside the upper mold (2); the perforated air-permeable blocks (21) are snap-fitted and connected inside the lower pressing sand core (34); and the bottom ends of the perforated air-permeable blocks (21) are connected to the corresponding air-permeable grooves (332).

8. The casting device for a mine wheel hub according to claim 1, characterized in that, A shunt pipe (22) is fixedly connected to the top of the upper mold (2), the input end of the shunt pipe (22) is plugged into the inside of the casting shell (12), a temporary storage space (36) corresponding to the shunt pipe (22) is opened inside the outer edge sand core (31), and the output end of the shunt pipe (22) is plugged into the inside of the temporary storage space (36).

9. The casting device of a mine car wheel hub according to claim 1, characterized in that, The top end of the casting shell (12) is located above the upper mold (2), and a clearance groove (121) is provided on the casting shell (12), wherein the clearance groove (121) is connected to the pouring groove (13) to ensure that the molten metal is poured into the casting molding cavity (5).

10. A casting device for a mine wheel hub according to claim 1, characterized in that, A column (41) is fixedly connected inside the partition mold (4), the top end of the column (41) is closely attached to the inner wall of the contoured sand core (33), and the bottom end of the column (41) is closely attached to the inner wall of the base (11).

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