A low-pressure casting mold for an aluminum gear housing

Abstract

A low-pressure casting mold for an aluminum gear housing comprises a metal mold mold composed of an upper mold and a lower mold, a gear inner cavity sand core, an upper mold cavity of the upper mold and a lower mold cavity of the lower mold forming a metal mold model cavity, the lower part of the gear inner cavity sand core is placed in the lower mold cavity of the lower mold, a casting cavity is formed between the upper surface of the gear inner cavity sand core and the upper mold cavity surface of the upper mold, two sets of pouring systems are connected to the casting cavity, the pouring system comprises a straight runner and a cross runner, the cross runner comprises a horizontal cross runner section and a vertical cross runner section, one end of the vertical cross runner section is connected to the inner end of the horizontal cross runner section, the other end of the vertical cross runner section is connected to the gear shrinkage feed runner, and the gear shrinkage feed runner is connected to the cavity located at the far end of the middle of the casting cavity for forming a gear inner cavity boss. The overall design of the mold conforms to the solidification temperature field gradient of the casting, and can prevent the casting from being retained in the mold, reduce deformation, and the pouring system has a wide shrinkage coverage and good shrinkage effect.

Description

Technical Field

[0001] The invention relates to an aluminum gear chamber casting mold and belongs to the field of casting equipment. Background Art

[0002] As one of the key parts of automobile engines, the gear chamber is installed between the cylinder block and the flywheel housing, and is connected to the cylinder head, starter, and oil pan. It has a built-in gear assembly, which plays the role of connecting the engine body and the carrier. The gear chamber is generally divided into gray iron or aluminum alloy, but aluminum alloy is more suitable for lightweight development requirements due to its light weight, so the market demand is increasing. With the continuous improvement of the integrated development of engine design, the aluminum gear chamber has a complex shape and large size, and has a concave structure. It is a large aluminum alloy thin-walled part. At present, this type of concave aluminum gear chamber usually adopts gravity casting process, but due to the large heat node of the gear inner cavity boss, the shrinkage compensation effect is poor, the product shrinkage is large, the aluminum liquid output rate is low, and the oxidation slag is seriously generated. Summary of the invention

[0003] The purpose of the present invention is to provide a low-pressure casting mold for an aluminum gear chamber, which meets the requirements of a low-pressure casting mold for an aluminum gear chamber with higher strength and rigidity and a complex shape.

[0004] In order to achieve the above-mentioned purpose of the invention, the technical solution of the present invention is: it includes a metal mold composed of an upper mold and a lower mold, a gear inner cavity sand core located in the metal mold model cavity, the upper cavity of the upper mold and the lower cavity of the lower mold constitute the metal mold model cavity, the lower part of the gear inner cavity sand core is placed in the lower cavity of the lower mold, and a casting cavity is formed between the upper surface of the gear inner cavity sand core and the upper cavity surface of the upper mold, two sets of pouring systems are connected to the casting cavity, the pouring system includes a straight runner and a cross runner, the cross runner includes a horizontal cross runner section and a vertical cross runner section overlapping the end face of the casting cavity, one end of the vertical cross runner section is connected to the inner end of the horizontal cross runner section, and the other end of the vertical cross runner section is connected to the gear shrinkage runner, and the gear shrinkage runner is connected to the cavity located at the far end of the middle of the casting cavity for forming a gear inner cavity boss.

[0005] The sprue is composed of a middle sprue located at the bottom of the gear inner cavity sand core and a lower sprue located on the lower mold. The upper mold corresponding to the sprue outlet is provided with a sprue nest, and the sprue inlet is connected to a riser pipe.

[0006] The gear shrinkage compensation runner is arranged on the gear inner cavity sand core, and a sand core positioning hole is also provided on the gear inner cavity sand core. The lower mold is provided with a positioning pin that cooperates with the sand core positioning hole for positioning, and the upper mold is provided with two runner nests. The outer end of the horizontal cross runner section is connected with the side of each middle straight runner, the upper part of the middle straight runner is connected with the runner nest, the lower part of the middle straight runner is connected with the lower straight runner, and the entrance of the lower straight runner is connected to the ceramic riser pipe.

[0007] The casting is a gear chamber, and the overlap length between the inner end of the horizontal runner section and the end face of the casting cavity exceeds the thermal node of the lower mounting surface of the gear chamber; after pouring, the outer surface of the casting cavity forms a joint surface with the engine cylinder block, and after pouring, the end face of the casting cavity forms the lower mounting surface of the gear chamber, and the lower mounting surface of the gear chamber is connected to the connecting surface of the flywheel housing.

[0008] The width L of the horizontal runner section is 2-3 times the overlap length between the inner end of the horizontal runner section and the end surface of the casting cavity, and the height difference H between the bottom surface of the horizontal runner section and the end surface of the casting cavity is at least 5 mm.

[0009] The upper mold is equipped with an upper mold insert connected by a screw, and a draw block with clearance fit is arranged in the upper mold insert; the draw block has a positioning flange that matches the side of the upper mold, and the inner end of the draw block forms a pit shape on the cylinder head surface. The function of the upper mold insert is to facilitate mold processing. If the upper mold insert can be processed separately, if the upper mold insert is not designed, the mold needs to dig a matching hole with the draw block, and the overall mold is not convenient to process. There is a hole on the upper mold insert that matches the draw block.

[0010] The positioning pin is arranged at the bottom of the lower cavity of the lower mold.

[0011] A filter screen is placed at the junction of the sprue and the cross runner and pressed between the sand core in the gear cavity and the lower mold.

[0012] The overall design of the mold conforms to the solidification temperature field gradient of the casting, and can prevent the casting from being retained in the mold and reduce deformation. The mold of the present invention has a high yield rate for low-pressure casting, and the gating system is easy to remove. The gating system has a wide shrinkage compensation coverage, good shrinkage compensation effect, and good slag avoidance effect.

[0013] During low-pressure casting, the lower mounting surface of the gear chamber faces downward, and two gating systems are set on the side and opposite side of the cylinder head surface, namely, double-gate low-pressure casting. A single gating system includes a casting cavity, a circular sprue, and a square runner. The square runner overlaps the lower mounting surface of the gear chamber, and the overlapping length mainly covers the thermal node of the lower mounting surface. The width L of the horizontal runner section is 2-3 times the end face width of the casting cavity. All the thermal nodes of the gear chamber can be compensated by adding a shrinkage channel on the sand core to compensate for the thick and large gear inner cavity boss to ensure its good quality. The gating system has a wide coverage and good effect. The filter screen is pressed by the gear inner cavity sand core and cannot move. The truncated cone-shaped sprue is small at the bottom and large at the top. A semi-spherical runner nest is provided on the upper part of the sprue. The riser nest can better buffer the aluminum liquid and reduce the generation of slag inclusions. One side of the gear inner cavity sand core forms the gear inner cavity shape, and the other side of the gear inner cavity sand core is provided with a gear shrinkage runner connected to the vertical runner section. A filter is placed at the junction of the sprue and the runner. The filter can be laid flat, and it will not move under the sand core, with a 100% filtering effect and good slag avoidance effect. This pouring system will not cause the aluminum liquid to be emptied, which can better ensure the product quality and improve the product qualification rate. The height difference H between the top surface of the horizontal runner section and the lower mounting surface of the gear chamber is at least 5mm, and the pouring system is very convenient to remove. During casting production, first place the filter at the circular sprue mouth of the bottom mold, then place the gear inner cavity sand core on the bottom mold, assemble the metal mold, and then perform low-pressure casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described in detail below with reference to the embodiments provided in the accompanying drawings;

[0015] Figure 1 It is a front view of the structural schematic diagram of the present invention;

[0016] Figure 2 It is a cross-sectional view of a schematic structural diagram of the present invention;

[0017] Figure 3 It is a schematic diagram of the structure of the pouring system of the present invention;

[0018] In the figure, 1, upper mold, 2, gear inner cavity sand core, 3, filter screen, 4, ceramic riser, 5, insulation furnace, 6, lower mold, 7, runner nest, 8, straight runner, 9, gear chamber casting, 10, cross runner, 11, gear shrinkage feed runner, 12, screw one, 13, upper mold insert, 14, puller block, 15, sand core positioning hole, 16, screw two, 17, lower mold cylindrical pin, 18, positioning flange, 19, gear inner cavity boss. DETAILED DESCRIPTION

[0019] Figure 1 , 2, 3, the present invention comprises a metal mold composed of an upper mold 1 and a lower mold 6, and a gear inner cavity sand core 2 located in the metal mold model cavity. The lower mold 6 is provided with two lower sprues, a lower mold cylindrical pin (i.e., positioning pin) 17 that cooperates with the sand core positioning hole 15 for positioning, the lower part of the lower mold cylindrical pin 17 is fixed to the lower mold 6 by screw 2 16, and the lower sprue inlet is connected to the ceramic riser pipe 4. The lower part of the gear inner cavity sand core is provided with a middle sprue, a cross runner 10 and a gear shrinkage feeder 11. The cross runner 10 includes a horizontal cross runner section and a vertical cross runner section, and the cross sections of the horizontal cross runner section and the vertical cross runner section are square. One side of the gear inner cavity sand core 2 forms the gear inner cavity shape of the flywheel housing joint surface, and the other side of the gear inner cavity sand core 2 is provided with a gear shrinkage feeder 11 connected to the gear inner cavity boss 19 and a positioning hole that cooperates with the lower mold cylindrical pin 17. The upper mold 1 forms the inner cavity shape of the cylinder joint surface. The upper mold is matched with an upper mold insert 13 connected by a screw 12. A draw block 14 with a clearance fit is provided in the upper mold insert 13. The draw block 14 has a positioning flange 18 that matches the side of the upper mold 1, forming a pit shape on the cylinder head surface to avoid the installation of the gear. The middle sprue located at the bottom of the sand core 2 in the inner cavity of the gear and the lower sprue located on the lower mold 6 form two sprues 8. The sprue 8 is truncated, small at the bottom and large at the top. The upper mold 1 is provided with a runner cavity 7 corresponding to the lower sprue on the lower mold. The area of ​​the filter screen 3 is larger than the area of ​​the sprue 8. During operation, the filter screen 3 is first laid flat to cover the two sprues 8 (gates) of the lower mold, and then the sand core is placed on the filter screen 3 through the positioning fit of the lower mold 6, and then the upper mold 1 is closed. The upper mold 1 presses the sand core 2 in the inner cavity of the gear to prevent it from running during the pouring process. Finally, push the block positioning flange 18 of the block 14 to be flush with the side of the upper mold. During operation, the aluminum liquid in the holding furnace 5 enters the sprue 8 from the ceramic riser 4, and the aluminum liquid passes through the filter 3 from the sprue 8 into the runner cavity 7, and then enters the horizontal runner 10 of the gear inner cavity sand core 2, and enters the casting cavity from the horizontal runner 10 to form the gear chamber casting 9. When removing the parts, first open the upper mold 1, then remove the block 14, and after the block is pulled out, it must be separated from the gear chamber casting 9, so that the gear chamber casting 9 can be taken out.

[0020] Figure 1 In the embodiment, the runner 10 can cover the heat sink on the flywheel housing joint surface of the aluminum gear chamber, and a gear feeding runner 11 connected to the runner 10 is provided on the middle distal gear inner cavity boss 19.

[0021] Figure 2 In the process, the sand core 2 is placed on the surface of the filter screen 3 and directly pressed, and the filter screen 3 can be laid flat and pressed underneath by the sand core without moving, with a 100% filtering effect and a good slag avoidance effect.

[0022] Figure 3In the figure, the bottom surface of the runner 10 exceeds the lower mounting surface of the gear chamber of the aluminum gear chamber casting 9 and is higher than the lower mounting surface of the gear chamber. When cutting from the lower mounting surface of the gear chamber, i.e., the flywheel housing connecting surface, the cutting area of ​​the exceeding surface is reduced, and the entire casting system can be removed, which is very convenient.

Claims

1. A low-pressure casting mold for an aluminum gear housing, characterized in that: The invention comprises a metal mold composed of an upper mold (1) and a lower mold (6), and a gear inner cavity sand core (2) located in the metal mold model cavity. The upper mold cavity of the upper mold (1) and the lower mold cavity of the lower mold (6) form the metal mold model cavity. The lower part of the gear inner cavity sand core (2) is placed in the lower mold cavity of the lower mold (6). The upper surface of the gear inner cavity sand core (2) and the upper mold cavity surface of the upper mold (1) form a casting cavity. Two sets of pouring systems are connected to the casting cavity. The pouring system comprises a straight runner (8) and a horizontal runner (10). The horizontal runner (10) comprises a horizontal runner section and a vertical runner section overlapped with the end surface of the casting cavity. One end of the vertical runner section is connected to the inner end of the horizontal runner section, and the other end of the vertical runner section is connected to the gear shrinkage feed runner (11). The gear shrinkage feed runner (11) is connected to the cavity located at the far end of the middle of the casting cavity for forming a gear inner cavity boss (19). During low-pressure casting, the lower mounting surface of the gear chamber faces downward, and two gating systems, namely, double-gate low-pressure casting, are set on the side and opposite side of the cylinder head surface; The sprue (8) is composed of a middle sprue located at the bottom of the gear inner cavity sand core (2) and a lower sprue located on the lower mold (6); a sprue pocket (7) is provided on the upper mold (1) corresponding to the sprue outlet, and the sprue inlet is connected to a liquid riser (4); The gear shrinkage compensation runner (11) is arranged on the gear inner cavity sand core (2), and the gear inner cavity sand core (2) is also provided with a sand core positioning hole (15), the lower mold (6) is provided with a positioning pin that cooperates with the sand core positioning hole for positioning, the upper mold (1) is provided with two runner pockets (7), the outer end of the horizontal cross runner section is connected to the side of each middle straight runner, the upper part of the middle straight runner is connected to the runner pocket (7), the lower part of the middle straight runner is connected to the lower straight runner, and the inlet of the lower straight runner is connected to the riser pipe (4); The casting is a gear chamber, and the overlap length between the inner end of the horizontal runner section and the end face of the casting cavity exceeds the thermal node of the lower mounting surface of the gear chamber; after pouring, the outer surface of the casting cavity forms a joint surface with the engine cylinder block, and after pouring, the end face of the casting cavity forms the lower mounting surface of the gear chamber, and the lower mounting surface of the gear chamber is connected to the connecting surface of the flywheel housing.

2. The aluminum gear housing low-pressure casting mold according to claim 1, characterized in that: The width L of the horizontal runner section is 2-3 times the overlap length between the inner end of the horizontal runner section and the end surface of the casting cavity, and the height difference H between the top surface of the horizontal runner section and the end surface of the casting cavity is at least 5 mm.

3. The aluminum gear housing low-pressure casting mold according to claim 1, characterized in that: The upper die (1) is matched with an upper die insert (13) connected by a screw (12), and a drawer block (14) with clearance fit is arranged in the upper die insert (13); the drawer block (14) has a positioning flange (18) matched with the side surface of the upper die, and the inner end of the drawer block (14) forms a concave shape on the cylinder head surface.

4. The aluminum gear housing low pressure casting mold according to claim 1, characterized in that: The positioning pin is arranged at the bottom of the lower cavity of the lower mold (6).

5. The aluminum gear housing low pressure casting mold according to claim 1, characterized in that: A filter screen (3) is placed at the junction of the sprue and the cross runner and pressed between the sand core (2) in the inner cavity of the gear and the lower mold (6).

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