A piston centrifugal casting mold and equipment

Abstract

This utility model discloses a piston centrifugal casting mold and equipment, relating to the field of engine component manufacturing technology. The piston centrifugal casting mold includes: a rotating base connected to a reducer, the reducer driving the rotating base to rotate on a fixed axis; a plug sand mold fixedly connected to the rotating base; a piston sand mold with an internal cavity, the piston sand mold and the plug sand mold cooperating to form a preset cavity, the upper surface of the piston sand mold having a pouring port and a riser, both communicating with the preset cavity; and a piston gating sand mold with a pouring channel on its surface, fixedly connected to the piston sand mold, the pouring channel communicating with the pouring port. The piston centrifugal casting mold and equipment provided in this application, through the reducer driving the rotating base, plug sand mold, piston sand mold, and piston gating sand mold to centrifugally rotate, allows impurities in the molten iron within the preset cavity to move to the riser, resulting in a low impurity content in the main body of the blank, improving the quality of the finished product, and thus significantly reducing the scrap rate.

Description

Technical Field

[0001] This utility model relates to the field of engine component manufacturing technology, and more specifically, to a piston centrifugal casting mold. Furthermore, this utility model also relates to equipment including the aforementioned piston centrifugal casting mold. Background Technology

[0002] The piston in an automobile engine is one of its core components. Currently, the mainstream pistons for passenger cars are lightweight aluminum alloy pistons. Due to their complex shape, aluminum alloy pistons are generally cast using low-pressure casting, while high-performance or high-load engine pistons are cast using extrusion casting. Cast iron pistons have better heat resistance than aluminum alloys, are less prone to deformation at high temperatures, and also have the advantages of good wear resistance and low cost, making them advantageous in low-speed, high-torque diesel engines and some older gasoline engines (such as those in commercial trucks). Cast steel pistons, due to their ultra-high strength, heat resistance, excellent wear resistance, and low coefficient of thermal expansion, are used in marine low-speed diesel engines, large construction machinery, and high-strength military engines. Cast iron pistons are mainly produced by sand casting, which is low-cost but has poor quality stability, with major defects including porosity, shrinkage cavities, and sand holes. Cast steel pistons rely on sand casting or investment casting, with high cost and high scrap rate being the main bottlenecks, and major defects including shrinkage cavities, hot cracks, and inclusions.

[0003] Centrifugal casting is a process that uses centrifugal force to force molten metal to adhere tightly to the mold cavity, making it particularly suitable for cylindrical, ring-shaped, or symmetrical parts (such as piston rings, cylinder liners, and pipes). Because the molten metal is forced against the outer wall of the mold during rotation, centrifugal casting effectively reduces defects such as porosity and shrinkage, resulting in a dense microstructure. Furthermore, the centrifugal force provides excellent feeding, generally eliminating the need for separate risers. However, centrifugal casting is generally only suitable for parts with rotational symmetry; it cannot produce complex, irregularly shaped parts. Therefore, centrifugal casting is generally not used for piston casting.

[0004] With the development of technology, some methods and corresponding equipment for producing pistons using centrifugal casting have gradually emerged. However, these methods cannot effectively remove impurities present in the molten iron and steel, resulting in the centrifugal casting process failing to effectively reduce casting defects, improve casting quality, and lower scrap rates.

[0005] In conclusion, how to reduce the scrap rate in centrifugal casting production is a problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0006] In view of this, the purpose of this utility model is to provide a piston centrifugal casting mold, which drives the plug sand mold, piston sand mold and piston gate sand mold to rotate on a fixed shaft through a reducer, and discharges impurities in the molten iron from the riser through centrifugal means, so as to reduce the scrap rate.

[0007] Another objective of this invention is to provide an apparatus including the aforementioned piston centrifugal casting mold.

[0008] To achieve the above objectives, this utility model provides the following technical solution:

[0009] A piston centrifugal casting mold includes:

[0010] A rotating base is connected to a reducer, which drives the rotating base to rotate on a fixed axis.

[0011] The plug mold is fixedly connected to the rotating base;

[0012] A piston sand mold with an internal cavity is provided. The piston sand mold and the plug sand mold are fitted together to form a preset cavity. The upper surface of the piston sand mold is provided with a pouring port and a riser. The pouring port and the riser are both connected to the preset cavity.

[0013] A piston-gating sand mold has a pouring channel on its surface. The piston-gating sand mold is fixedly connected to the piston sand mold, and the pouring channel is connected to the pouring port.

[0014] Preferably, a recess is provided at the center of the upper surface of the rotating base, and a boss matching the recess is provided at the center of the lower surface of the plug sand mold.

[0015] Preferably, the piston gate sand mold has a cap-shaped structure, and the edge of the piston gate sand mold is provided with a first annular protrusion, the edge of the plug sand mold is provided with a second annular protrusion, the piston gate sand mold and the edge of the piston sand mold are connected by glue, and the edge of the piston sand mold and the plug sand mold are connected by glue.

[0016] Preferably, the inner diameter of the first annular protrusion is the same as the inner diameter of the second annular protrusion, and both are the same as the outer diameter of the piston sand mold.

[0017] Preferably, the pouring channel includes a vertical runner and a horizontal runner. A third annular protrusion is provided at the center of the side surface of the piston gate sand mold opposite to the piston sand mold. The vertical runner is located inside the third annular protrusion, and the horizontal runner is located inside the piston gate sand mold. The two ends of the horizontal runner are respectively connected to the vertical runner and the pouring gate.

[0018] Preferably, the piston gate sand mold has a rectangular hole on the side surface facing away from the piston sand mold, and the rectangular hole communicates with the riser.

[0019] Preferably, the pouring gate and the riser are arranged in pairs, and the two pouring gates and risers in the pair are symmetrically arranged about the center point of the upper surface of the piston sand mold.

[0020] Preferably, the lower surface of the rotating base is provided with a tubular structure, which is used to connect the reducer.

[0021] Preferably, the cavity of the piston sand mold is provided with an irregular structure, and the upper surface of the plug sand mold is provided with an arc-shaped protrusion.

[0022] An apparatus comprising a piston centrifugal casting mold, wherein the piston centrifugal casting mold is any of the piston centrifugal casting molds described above.

[0023] This utility model provides a piston centrifugal casting mold, comprising a rotating base, a plug sand mold, a piston sand mold, and a piston gate sand mold connected in sequence. The rotating base is connected to a reducer, which drives the rotating base to rotate on a fixed axis. Since the rotating base, plug sand mold, piston sand mold, and piston gate sand mold are fixedly connected in sequence, the reducer can simultaneously drive the rotating base, plug sand mold, piston sand mold, and piston gate sand mold. A preset cavity can be formed between the plug sand mold and the piston sand mold. A casting channel communicating with the casting port is provided on the piston gate sand mold. The pouring channel pours molten iron into the plug sand mold and piston sand mold. With the rotation of the reducer, the uppermost part of the pouring gate is higher than the riser due to the setting of the piston pouring sand mold. As the reducer rotates, due to the centrifugal force, the pressure is greater where the diameter is larger and less where the diameter is smaller. Impurities will drift towards the smaller diameter areas. During the entire pouring process, impurities in the molten iron can drift towards the areas of lower pressure. Under the action of gravity, the impurities will move to the riser, so that the impurity content is extremely low after the casting cools, thereby reducing the scrap rate. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a front view of the piston centrifugal casting mold provided by this utility model;

[0026] Figure 2 for Figure 1 Cross-sectional view at position AA;

[0027] Figure 3 This is an exploded view of the piston centrifugal casting mold provided by this utility model.

[0028] Figure label:

[0029] 1-Rotating base; 101-Recess; 2-Plug sand mold; 201-Boss; 202-Second annular protrusion; 3-Piston sand mold; 301-Gating gate; 302-Riser; 4-Piston gate sand mold; 401-Gating channel; 4011-Vertical runner; 4012-Horizontal runner; 402-First annular protrusion; 403-Third annular protrusion; 404-Rectangular hole. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] The core of this utility model is to provide a piston centrifugal casting mold, which can be driven by a reducer to rotate centrifugally, so that impurities in the molten iron can flow to the riser, thereby reducing impurities in the main blank, improving the quality of the finished product, and reducing the scrap rate.

[0032] Another core aspect of this invention is to provide an apparatus that includes the aforementioned piston centrifugal casting mold.

[0033] It should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", "front", and "rear" is based on the orientation or positional relationship shown in the accompanying drawings and is only for the purpose of facilitating the description of this application and simplifying the description. It is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0034] This application provides a piston centrifugal casting mold, comprising:

[0035] Among them, the rotating base 1, the plug sand mold 2, the piston sand mold 3, and the piston gate sand mold 4;

[0036] The rotating base 1 is connected to the reducer, which is used to drive the rotating base 1 to rotate on a fixed axis.

[0037] The plug sand mold 2 is fixedly connected to the rotating base 1;

[0038] The piston sand mold 3 has a built-in cavity. The piston sand mold 3 and the plug sand mold 2 cooperate to form a preset cavity. The upper surface of the piston sand mold 3 is provided with a pouring port 301 and a riser 302. The pouring port 301 and the riser 302 are both connected to the preset cavity.

[0039] The surface of the piston gate sand mold 4 is provided with a pouring channel 401. The piston gate sand mold is fixedly connected to the piston sand mold 3 so that the pouring channel 401 is connected to the pouring port 301.

[0040] For details, please refer to the appendix. Figure 1 The overall structure, from bottom to top, consists of a rotating base 1, a plug sand mold 2, a piston sand mold 3, and a piston gating sand mold 4. These components are sequentially and fixedly connected. A reducer is connected to the center of the lower part of the rotating base 1. During rotation, the reducer drives the entire casting mold in a centrifugal motion. The plug sand mold 2 and the piston sand mold 3 form a pre-set cavity. The piston gating sand mold 4 is located at the upper end of the piston sand mold 3. The piston sand mold 3 has a pouring port 301 and a riser 302. The piston sand mold 4 has a pouring channel 401 connected to the pouring port 301. After molten iron is poured into the pouring channel 401, it flows along the pouring channel 401 and the pouring port 301 into the pre-set cavity. As the reducer operates, the entire casting mold enters a centrifugal state. In the liquid state, impurities... The density of the molten iron is less than that of the molten iron, so impurities will drift towards areas of lower pressure. The molten iron level at the pouring gate 301 is higher than that at the riser 302, and under the influence of gravity, impurities drift towards the riser 302. Due to centrifugal force, the pressure is higher where the diameter is larger and lower where the diameter is smaller, so impurities will drift towards areas of smaller diameter. Except for the pouring gate 301 and riser 302, other areas form a closed cavity. The molten iron level at the pouring gate 301 is always the highest, and the molten iron pressure is higher than that at the riser 302. The molten iron can only drift towards the riser 302 after filling the cavity. Therefore, the riser 302 is the final location where the molten iron arrives. The excess molten iron has two functions: to carry out impurities and to provide feeding during solidification. The main body of the formed blank has a low impurity content, which improves the quality of the finished product and thus significantly reduces the scrap rate.

[0041] Based on the above embodiment, a recess 101 is provided at the center of the upper surface of the rotating base 1, and a boss 201 matching the recess 101 is provided at the center of the lower surface of the plug sand mold 2.

[0042] Specifically, a recess 101 is provided at the center of the upper surface of the rotating base 1. The shape of the recess 101 is not limited; it can be a circular recess, a square recess, or a rectangular recess. A boss 201 is provided on the lower surface of the plug sand mold 2. The shape and size of the boss 201 match the recess 101, so that the plug sand mold 2 can rotate centrifugally synchronously with the rotating base 1, eliminating eccentricity during rotation.

[0043] Based on the above embodiment, the piston gate sand mold 4 has a cap-shaped structure, and the edge of the piston gate sand mold 4 is provided with a first annular protrusion 402, and the edge of the plug sand mold 2 is provided with a second annular protrusion 202. The edges of the piston gate sand mold 4 and the piston sand mold 3 are connected by glue, and the edges of the piston sand mold 3 and the plug sand mold 2 are connected by glue.

[0044] For details, please refer to the appendix. Figure 2 With appendix Figure 3 The piston sand mold 3 has a cylindrical structure on the outside, and the piston gate sand mold 4 has a cap-like structure that can be fastened on top of the piston sand mold 3. The upper surface edge of the plug sand mold 2 is provided with a second annular protrusion 202, and the lower surface edge of the piston gate sand mold 4 is provided with a first annular protrusion 402. The edges of the piston gate sand mold 4 and the piston sand mold 3 are connected by glue, and the edges of the piston sand mold 3 and the plug sand mold 2 are connected by glue to prevent the plug sand mold 2, the piston sand mold 3 and the piston gate sand mold 4 from spinning freely.

[0045] Based on the above embodiments, the inner diameter of the first annular protrusion 402 is the same as the inner diameter of the second annular protrusion 202, and both are the same as the outer diameter of the piston sand mold 3.

[0046] Specifically, the inner diameters of the first annular protrusion 402 and the second annular protrusion 202 are the same, and both are the same as the outer diameter of the piston sand mold 3, so that the three can fit together tightly, and the tiny gaps are sealed with glue to prevent molten iron from leaving the preset cavity and improve the safety factor.

[0047] Based on the above embodiment, the pouring channel 401 includes a vertical runner 4011 and a horizontal runner 4012. A third annular protrusion 403 is provided at the center of the side surface of the piston gate sand mold 4 away from the piston sand mold 3. The vertical runner 4011 is located inside the third annular protrusion 403, and the horizontal runner 4012 is located inside the piston gate sand mold 4. The two ends of the horizontal runner 4012 are connected to the vertical runner 4011 and the pouring port 301, respectively.

[0048] For details, please refer to the appendix. Figure 2 With appendix Figure 3 The pouring channel 401 includes a vertical gating channel 4011 arranged in a vertical direction and a horizontal gating channel 4012 arranged in a horizontal direction. The horizontal gating channel 4012 is connected to the vertical gating channel 4011. The other end of the horizontal gating channel 4012 is connected to the pouring port 301. A third annular protrusion 403 is provided on the upper surface of the piston gating sand mold 4. The vertical gating channel 4011 is located inside the third annular protrusion 403. When pouring molten iron, the molten iron can pass through the vertical gating channel 4011 and the horizontal gating channel 4012 in sequence, and then flow into the preset cavity from the pouring port 301.

[0049] Based on the above embodiment, the piston gate sand mold 4 is also provided with a rectangular hole 404 on the side surface opposite to the piston sand mold 3, and the rectangular hole 404 is connected to the riser 302.

[0050] Specifically, an open rectangular hole 404 is provided on the piston gate sand mold 4. The rectangular hole 404 is connected to the riser 302 to prevent molten iron and impurities from splashing out from the riser 302 during centrifugation. It can also serve as a heat dissipation hole to dissipate heat.

[0051] Based on the above embodiment, the pouring port 301 and the riser 302 are arranged in pairs, and the two pouring ports 301 and risers 302 in the pair are symmetrically arranged about the center point of the upper surface of the piston sand mold 3.

[0052] For details, please refer to the appendix. Figure 2 There are two pouring gates 301, which are symmetrically arranged about the center of the upper surface of the piston sand mold 3. There are two horizontal runners 4012, and both horizontal runners 4012 are connected to the vertical runner 4011. The two horizontal runners 4012 are connected to the two pouring gates 301 respectively to improve the pouring efficiency. The riser 302 is arranged at intervals with the pouring gate 301. There are also two risers 302, which can fully accommodate the impurities discharged by the centrifugation of molten iron.

[0053] Based on the above embodiment, the lower surface of the rotating base 1 is provided with a tubular structure, which is used to connect the reducer.

[0054] For details, please refer to the appendix. Figure 2 The lower surface of the rotating base 1 is provided with a tubular structure. The output end of the reducer can be inserted into the tubular structure and fixedly connected to the bottom of the rotating base 1, so that the rotation of the output end of the reducer can drive the rotating base 1 to rotate synchronously centrifugally.

[0055] Based on the above embodiments, the cavity of the piston sand mold 3 is provided with an irregular structure, and the upper surface of the plug sand mold 2 is provided with an arc-shaped protrusion.

[0056] Specifically, in some existing technologies, the cavity of the piston head is located at the top, which makes the density and strength of the head of the piston, which needs to withstand high temperature and high pressure, lower than other parts. However, the upper side of the cavity of the piston sand mold 3 has an irregular structure, and the upper surface of the plug sand mold 2 has an arc-shaped protrusion, so that the cavity of the piston head is located at the bottom, which improves the density of the structure.

[0057] When casting cast iron pistons, taking QT600 as an example, the composition ratio is as follows: C: 3.5-3.9%, Si: 2.5-3.0%, S≤0.02%, P≤0.03%, Mn: 0.55-0.65%, Cu: 0.3-0.5%, Sn: 0.01-0.03%.

[0058] Regarding the casting process:

[0059] 1. After the molten iron is melted, it is heated to 1480-1520℃ and held in a holding furnace;

[0060] 2. Add 0.9%-1.1% spheroidizing agent to the ladle, and add 1.2%-1.4% inoculant to cover the spheroidizing agent. Pour the molten iron into the transfer ladle and wait 3-5 minutes for spheroidizing to be completed.

[0061] 3. Pour the molten iron into the pouring port 301 in the middle of the piston pouring sand mold 4. At this time, the reducer driven by the motor drives the rotating base 1 to rotate at a speed of 40-100 revolutions per minute. After the internal cavity of the piston is filled, the excess molten iron, along with impurities, overflows from the two risers 302 located above the piston sand mold 3.

[0062] After pouring, the rotation speed was reduced to 20 rpm, and the casting was completely solidified after rotating for another 20 minutes.

[0063] 4. When the temperature reaches 550-650℃, remove the workpiece and place it in an insulated box for strengthening treatment for 3 hours. After treatment, let it cool completely, remove the impurity structure at riser 302, and obtain a qualified blank after shot blasting.

[0064] When casting cast steel pistons, taking 42CrMoA as an example, the composition ratio is as follows: C: 0.38-0.46%, S: ≤0.02%, P≤0.025%, Si: 0.8-1%, Mn: 1.15-1.35%, Cr: 0.1-0.2%, Mo: 0.2-0.3%, Ni: 0.2-0.3%.

[0065] Regarding the casting process:

[0066] 1. Molten steel with qualified composition is heated to 1620-1670℃ in a holding furnace;

[0067] 2. When tapping, add 0.15%-0.2% deoxidizer to the ladle. After the ladle is filled with molten steel, add 0.05%-0.1% deoxidizer to the surface of the molten steel, stir and remove slag, add 200g-300g slag-collecting agent to cover the surface of the molten steel, and then pour the molten steel.

[0068] Deoxidizers deoxidize molten steel, while covering agents prevent the molten steel from directly contacting air and causing oxidation.

[0069] 3. Pour the molten steel into the pouring port 301 in the middle of the piston sand mold 4. At this time, the reducer driven by the motor drives the rotating base 1 to rotate at a speed of 20-80 revolutions per minute. After the internal cavity of the piston is filled, the excess molten steel, along with impurities, overflows from the two risers 302 located above the piston sand mold 3. After pouring, continue to rotate for 20 minutes until the casting is completely solidified and the temperature reaches 550-650℃.

[0070] 4. Remove the workpiece, place it in the blank frame, and after it has completely cooled, remove the structure at riser 302 and perform shot blasting.

[0071] 5. The steel piston blank is normalized by heating to 860-890℃ and holding for 3-4 hours. After being taken out of the furnace, it is air-cooled.

[0072] Advantages of cast steel pistons: The use of gravity and centrifugal force allows impurities in the steel piston blank to quickly float out during solidification, solving the problem of slag inclusions in steel pistons; the use of a covering agent to isolate air prevents oxidation of molten steel during pre-casting transport. This facilitates multi-station, automated production, improving efficiency and reducing costs.

[0073] In addition to the piston centrifugal casting mold described above, this utility model also provides a device that includes the piston centrifugal casting mold disclosed in the above embodiments. For the structure of other parts of the device, please refer to the prior art, which will not be repeated here.

[0074] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0075] The present invention provides a detailed description of a piston centrifugal casting mold and equipment. Specific examples have been used to illustrate the principle and implementation of the present invention. The descriptions of these embodiments are merely for the purpose of helping to understand the method and core idea of ​​the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A piston centrifugal casting mold, characterized in that, include: A rotating base (1) is connected to a reducer, which is used to drive the rotating base (1) to rotate on a fixed axis. The plug sand mold (2) is fixedly connected to the rotating base (1); Piston sand mold (3) with built-in cavity. The piston sand mold (3) and the plug sand mold (2) cooperate to form a preset cavity. The upper surface of the piston sand mold (3) is provided with a pouring port (301) and a riser (302). The pouring port (301) and the riser (302) are both connected to the preset cavity. The piston gate sand mold (4) has a pouring channel (401) on its surface. The piston gate sand mold is fixedly connected to the piston sand mold (3) so that the pouring channel (401) is connected to the pouring port (301).

2. The piston centrifugal casting mold according to claim 1, characterized in that, A recess (101) is provided at the center of the upper surface of the rotating base (1), and a boss (201) matching the recess (101) is provided at the center of the lower surface of the plug sand mold (2).

3. The piston centrifugal casting mold according to claim 1, characterized in that, The piston gate sand mold (4) has a cap-shaped structure, and the edge of the piston gate sand mold (4) is provided with a first annular protrusion (402), and the edge of the plug sand mold (2) is provided with a second annular protrusion (202). The edges of the piston gate sand mold (4) and the piston sand mold (3) are connected by glue, and the edges of the piston sand mold (3) and the plug sand mold (2) are connected by glue.

4. The piston centrifugal casting mold according to claim 3, characterized in that, The inner diameter of the first annular protrusion (402) is the same as the inner diameter of the second annular protrusion (202), and both are the same as the outer diameter of the piston sand mold (3).

5. The piston centrifugal casting mold according to claim 1, characterized in that, The pouring channel (401) includes a vertical runner (4011) and a horizontal runner (4012). A third annular protrusion (403) is provided at the center of the side surface of the piston gate sand mold (4) away from the piston sand mold (3). The vertical runner (4011) is located inside the third annular protrusion (403). The horizontal runner (4012) is located inside the piston gate sand mold (4). The two ends of the horizontal runner (4012) are respectively connected to the vertical runner (4011) and the pouring gate (301).

6. The piston centrifugal casting mold according to claim 5, characterized in that, The piston gate sand mold (4) is provided with a rectangular hole (404) on the side surface away from the piston sand mold (3), and the rectangular hole (404) is connected to the riser (302).

7. The piston centrifugal casting mold according to claim 1, characterized in that, The pouring port (301) and the riser (302) are respectively arranged in pairs, and the two pouring ports (301) and the riser (302) in the pair are symmetrically arranged about the center point of the upper surface of the piston sand mold (3).

8. The piston centrifugal casting mold according to claim 1, characterized in that, The lower surface of the rotating base (1) is provided with a tubular structure, which is used to connect the reducer.

9. The piston centrifugal casting mold according to any one of claims 1 to 8, characterized in that, The piston sand mold (3) has an irregular structure inside its cavity, and the upper surface of the plug sand mold (2) has an arc-shaped protrusion.

10. An apparatus comprising a piston centrifugal casting mold, characterized in that, The piston centrifugal casting mold is the piston centrifugal casting mold as described in any one of claims 1 to 9.

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