Large excavator counterweight casting system

Abstract

A gating system for large excavator counterweight castings includes a rectangular gating system surrounding the outer periphery of the casting cavity. This rectangular gating system comprises: a horizontal gating system suspended in a slot on one side of the casting cavity; an inner gating system connected to both sides of the horizontal gating system; auxiliary gating systems located between the two wings of the casting cavity and in slots on the other side of the casting cavity; a sprue positioned on the horizontal gating system and connected to the pouring cup; two vented risers on each wing of the casting cavity; an auxiliary venting riser located between the two vented risers; and the bottoms of the three risers connected to form a connecting tie. This invention solves the problems of difficulty in filling and feeding in conventional V-process casting systems for large excavator counterweights, while significantly reducing defects such as dimensional deformation, surface expansion, and casting bending.

Description

Technical Field

[0001] This invention belongs to the field of casting technology, specifically relating to a casting system for a large excavator counterweight. Background Technology

[0002] When using the V-process to produce large excavator counterweight castings with complex structures, the traditional mold design, based on the U-shaped shape of these castings and the bottom-pouring gating system (with a static pressure height of 1145mm), often results in significant dimensional deformation and weight deviation due to sand grain movement under the static pressure of the molten iron. Furthermore, existing gating structures are difficult to fill completely, lack proper shrinkage compensation, and have low yields. Additionally, the uneven wall thickness and complex shape of the excavator counterweight castings, along with the tendency for structures extending beyond the body at all four ends to deform, coupled with the lack of anti-deformation measures in existing gating systems, lead to defects such as dimensional deformation, surface bulging, and bending. This results in a large number of castings requiring repair or even scrapping, resulting in low production efficiency. Summary of the Invention

[0003] In view of the above problems, the technical problem to be solved by the present invention is to provide a casting system for large excavator counterweight castings, which solves the problems of difficulty in filling and feeding in conventional V-process casting systems for large excavator counterweight castings, while significantly reducing the problem of defective products due to casting deformation and improving the yield.

[0004] According to the technical solution of the present invention, a casting system for a large excavator counterweight casting is provided, comprising a casting unit: a rectangular gating system arranged around the outer periphery of the casting cavity, the rectangular gating system comprising: a horizontal gating system suspended at a slot on one side of the casting cavity, an inner gating system connected to both sides of the horizontal gating system, and an auxiliary gating system arranged in the middle of the two wings of the casting cavity and at a slot on the other side of the casting cavity; a feeding unit: a sprue arranged on the horizontal gating system, the sprue being connected to the pouring cup; and a feeding unit: two lead-out risers are respectively arranged on the two wings on each side of the casting cavity, an auxiliary venting riser is added between the two lead-out risers, and the bottoms of the three risers are connected to form a connecting tie.

[0005] Furthermore, the height of the direct sprue is 597mm.

[0006] Furthermore, the cross-sectional area ratio of the straight runner, the horizontal runner, and the ingate is S_straight:S_horizontal:S_ingate = 1.0:1.4~1.6:1.08~1.10.

[0007] Furthermore, the inner gating system is in the form of a thick sheet, with a thickness of 70 mm and a width of 100 mm, and is introduced horizontally in the same direction.

[0008] Furthermore, a filter system is installed on the horizontal runner.

[0009] Furthermore, the filter system uses a 120mm*120mm*20mm foam ceramic filter screen.

[0010] Furthermore, the feeding unit also includes a direct venting riser located at the central protrusion of the casting cavity.

[0011] Furthermore, the rectangular gating system is arranged in close proximity to the sand mold surrounding the casting cavity.

[0012] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0013] 1. This invention modifies the sprue in a conventional bottom-pouring gating system into a detachable design, forming a top-pouring gating system. After solidification, the gating unit acts as a reinforcing rib, effectively reducing product deformation. It can also reduce the static pressure of product pouring, making the pouring temperature gradient more reasonable, facilitating shrinkage compensation, and further increasing the process yield.

[0014] 2. This invention moves the riser location in the conventional gating system to the two wings of the casting, which facilitates the subsequent cleaning process. At the same time, the bottoms of the risers are connected together to form an outer tie rod, which restrains the tension on both sides of the casting and reduces the tendency to deform. Inner runners are installed on both wings of the casting, which can serve as both runners and tie rods, reducing the inward bending deformation of the two wings.

[0015] 3. The casting system of the present invention is suitable for casting excavator-type castings with thin walls, complex shapes, and large dimensions. It can solve defects such as casting expansion, deformation, and overweight, and can increase the product qualification rate to over 95%. It can also save time for finishing, repair, and grinding operations and improve production efficiency. Attached Figure Description

[0016] Figure 1 : A schematic diagram of an embodiment of the casting system for the counterweight of a large excavator according to the present invention.

[0017] Figure 2 : Figure 1 A partial structural disassembly diagram of the embodiment shown. Detailed Implementation

[0018] like Figure 1As shown, this is an embodiment of the large excavator counterweight casting system of the present invention, mainly composed of a feeding unit, a casting unit, and a feeding unit. The casting unit includes a rectangular gating system surrounding the outer circumference of the casting cavity. The rectangular gating system further includes a horizontal gating 1 located in a slot on one side of the casting cavity 10, an inner gating 2 connected to both sides of the horizontal gating 1, and auxiliary gating systems 3 located in the middle of the two wings of the casting cavity 10 and in a slot on the other side of the casting cavity 10. The feeding unit includes a sprue 4 and a pouring cup. The sprue 4 is located on the horizontal gating 1 and is connected to the pouring cup (not shown in the figure). This invention places the gating system at the top, forming a top-pouring casting system, increasing the gap with the casting cavity, reducing the risk of sand mold deformation due to decreased sand mold hardness during casting, and improving the casting system's resistance to molten iron erosion.

[0019] On another front, compared to traditional casting systems where the sprue and runner are fixed within the sand mold, their distribution and connection characteristics limit their ability to provide reinforcement. This invention positions the sprue and runner at slots within the casting cavity and elevates them, allowing them to be directly carried out with the sand mold after completion and removed from the side. Figure 2 As shown, the sprue and gating system form a "detachable" design. Meanwhile, the sprue 4, gating 1, and ingate 2, arranged around the outer periphery of the casting cavity, combine to form an integral tie, which can reduce stress on both sides of the casting. In particular, the ingates located on the two wings of the casting can reduce the probability of inward bending deformation of the wings.

[0020] In addition, in this embodiment, the height of the sprue 4 is set to 597mm, which significantly shortens the height of the sand mold. Compared with the traditional casting system, the static pressure of the molten iron is significantly reduced, ensuring that the first casting cools first and eliminating the deformation of the sand mold caused by the decrease in hardness during casting.

[0021] A filter system can also be installed on the horizontal runner 1. In this embodiment, a 120mm*120mm*20mm foam ceramic filter screen is selected, which can effectively remove or reduce inclusions in the molten metal, improve the purity of the molten metal, make the cast products smooth, uniform in structure, and strong, and reduce the slag porosity of the castings.

[0022] After passing through the filter screen system, the molten iron enters the ingate 2 along the horizontal sprue 1. The ingate 2 is arranged close to the sand mold (not shown in the figure). The ingate 2 can be in the form of a thick sheet, such as 70 mm thick and 100 mm wide, and is introduced horizontally in the same direction to facilitate the molten iron to enter the casting cavity 10 faster. At the same time, the auxiliary sprue 3 set between the two wings of the casting cavity 10 can also increase the filling speed.

[0023] As shown in the figure, the feeding unit in this embodiment includes two lead-out risers 51 respectively provided on the two wings of each side of the casting cavity 10. The bottoms of the two risers are connected to discharge the gas released from the cavity, as well as the molten metal and slag that filled the cavity beforehand. An auxiliary venting riser 52 is added between the two lead-out risers 51 to discharge the gas generated after the molten iron convection, avoiding the explosion caused by the inability to discharge the gas from the cavity. At the same time, the bottoms of these three risers are connected to form a connecting tie, which can restrain the tension on both sides of the casting and reduce the tendency to deform.

[0024] In this embodiment, two direct-vent risers 53 are provided at the middle protrusion of the casting cavity 10 to exhaust the gas generated inside the cavity.

[0025] Compared to the original casting system, this invention sets the cross-sectional area ratio of the sprue, grate, and ingate to S_sprue:S_grate:S_ingate = 1.0:1.4~1.6:1.08~1.10, so that the molten metal can flow in fully during the entire filling process and enter a sequential solidification state. This ensures that when the molten iron is filled and distributed, the part far from the riser solidifies first, the part near the riser solidifies later, and the riser itself solidifies last.

Claims

1. A casting system for a large excavator counterweight, characterized in that, include: Gating unit: A rectangular gating system is set around the outer periphery of the casting cavity. The rectangular gating system includes: a horizontal gating system that is suspended in a slot on one side of the casting cavity, an inner gating system that is connected to both sides of the horizontal gating system, and an auxiliary gating system that is set in the middle of the two wings of the casting cavity and in a slot on the other side of the casting cavity. Feeding unit: A sprue is provided on the horizontal runner, and the sprue is connected to the pouring cup; Feeding unit: Two lead-out risers are set on each of the two wings on each side of the casting cavity. An auxiliary venting riser is added between the two lead-out risers, and the bottoms of the three risers are connected to form a connecting tie. The height of the sprue is 597 mm; The cross-sectional area ratio of the straight runner, horizontal runner, and ingate is S_straight:S_horizontal:S_ingate = 1.0:1.4~1.6:1.08~1.10; The ingate is made of a thick sheet, 70mm thick and 100mm wide, and is introduced horizontally in the same direction.

2. The casting system for large excavator counterweights as described in claim 1, characterized in that, A filter system is installed on the horizontal runner.

3. The casting system for large excavator counterweights as described in claim 2, characterized in that, The filter system uses a 120mm*120mm*20mm foam ceramic filter screen.

4. The casting system for large excavator counterweights as described in claim 1, characterized in that, The feeding unit also includes a direct venting riser located at the center protrusion of the casting cavity.

5. The casting system for large excavator counterweights as described in claim 1, characterized in that, The rectangular gating system is arranged in close proximity to the sand mold around the casting cavity.

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