Casting method for large diesel engine cylinder block

Abstract

A casting method for a large diesel engine cylinder block is provided. By sequentially optimizing the design of the parting surface, the pouring system, the riser, the air outlet, the chiller, and the lock box, the convenience of pounding sand and the accuracy of box assembly are ensured, oxidation inclusion defects caused by turbulence are reduced, the occurrence of porosity defects is reduced, the solidification speed of thick and large parts is fast, the position of the sand box is stable and reliable, and the problems of large shrinkage tendency and frequent porosity defects of the cylinder block are effectively solved. The production of large cylinder block castings is stabilized, and the process assurance is high and the casting quality is stable.

Description

Technical Field

[0001] The invention belongs to the technical field of diesel engine cylinder block casting, and in particular relates to a casting method for a large diesel engine cylinder block. Background Art

[0002] As a key component of diesel engines, large diesel engine cylinder blocks must possess high quality and precision. A certain diesel engine cylinder block is made of HT250 material, has a gross weight of 34.5 tons, a primary wall thickness of 60 to 80 mm, and dimensions of approximately 4100 mm × 2065 mm × 2170 mm. Its liquid weight reaches 40.5 tons. It utilizes an open bottom-pouring, rain-shower pouring system with a filter, with the lower plane facing upward. Fourteen Φ280 insulated top risers are used. Chills, 60 to 80 mm thick and made of HT200, are installed on the cylinder bore surface and the bushing box. Sand cores are installed on the top surface of each bolt hole and stuffing box core for ventilation. However, due to the large and uneven wall thickness, complex structure, and large variations in solidification time between different areas, as well as the high sensitivity of specific areas of gray cast iron, shrinkage defects exist on the lower plane. Porosity often appears on the lower plane and along the window edges, containing small amounts of slag, seriously affecting the surface quality of the casting. Therefore, improvements are necessary to address these issues. Summary of the Invention

[0003] The technical problem solved by the present invention is as follows: A casting method for a large diesel engine cylinder block is provided, which ensures the convenience of sand pounding and the accuracy of box assembling by sequentially optimizing the design of the parting surface, the optimization design of the pouring system, the optimization design of the riser, the optimization design of the air outlet, the optimization design of the chiller and the optimization design of the lock box, reduces the oxidation slag defects caused by turbulence, reduces the generation of air hole defects, accelerates the solidification speed of thick and large parts, and stabilizes and reliably positions the sand box, effectively solves the problems of large shrinkage tendency and frequent air hole defects of the cylinder block, stabilizes the production of large cylinder block castings, and has high process assurance and stable casting quality.

[0004] The technical solution adopted by the present invention is a large diesel engine cylinder block casting method, and the specific optimization steps are as follows:

[0005] 1) Parting surface design: A four-opening mold with the lower plane facing upward and including parting surface 1, parting surface 2 and parting surface 3;

[0006] 2) Gating System Design: An open bottom-pouring, rain-shower gating system with a filter is employed. The sprues on both sides of the mold utilize Φ100mm ceramic tubes. The runners connected to the sprues are rectangular cross-sections surrounding the cylinder block. Several filters are installed on the runners, and the ingates connected to the runners through the filters utilize Φ40mm porcelain tubes. The sprues act as flow-blocking sections, allowing molten iron to flow from the sprues to the runners, then through the filters and dispersedly introduced from the lowest surface of the mold cavity. Combined with the open ingates, this ensures a steady rise in the molten iron level.

[0007] 3) Riser Design: Multiple 280mm Φ insulation risers are located at the highest point of the mold's upper surface and distributed on the lower planes of the air inlet and exhaust sides, as well as the lower planes of the free end. Each riser is elevated. Two cavity vents are located on each rib and stuffing box hole on the mold's upper surface. Sand core vent hole 1 runs centrally through the stuffing box hole. Each sand core vent hole 1 serves as a 130mm Φ through-hole exhaust channel for enlarged core venting. Sand core vent hole 2 runs centrally through the bolt hole core.

[0008] 4) Chill design: Chills are placed on the surface of the cylinder body in the cavity where the wall thickness is greater than 100 mm. The thickness of the chill is designed to be 2 / 3 of the wall thickness of the cooled part. Chills include flat chills and contoured chills.

[0009] 5) Weight Arrangement: Eight casting weights are used to hold down the flask. These eight weights are arranged in two groups of four, with the spacing between adjacent weights no greater than 1000mm. Two weights are located in the middle of the flask to prevent the molten iron from floating, centered along the length of the mold. The other two weights are located at the edges of the mold.

[0010] 6) Sand box locking design: Use a locking device to fix the corresponding casting weights at the upper and lower positions and lock the box, and fix the angle irons used to tighten the corners of the sand box on the side where the casting weights face the sand box;

[0011] 7) Pouring cup design: Two 5T quantitative pouring cups and two 20T ladles are used for simultaneous pouring from both sides of the sand box. During pouring, the weight and temperature of the molten iron in the two ladles are ensured to be basically the same, so as to ensure that the molten iron in the two ladles will not form defects such as cold shut due to the temperature difference of the molten iron when they meet at the bottom of the cavity.

[0012] In the above step 3), there are fourteen thermal insulation risers in total, six of which are provided on the air inlet side and the exhaust side of the lower plane, and two are provided on the free end.

[0013] Furthermore, the heat-insulating riser is raised by 150 mm on the basis of the original height, the diameter of the cavity air outlet is Φ20 mm, the diameter of the sand core air outlet hole 1 is Φ130 mm, and the diameter of the sand core air outlet hole 2 is Φ20 mm.

[0014] In the above step 4), the size of the chill is 200 mm×100 mm, and the gap between the chills is between 20 and 30 mm.

[0015] In the above step 5), the specifications of the casting weight are 4700mm×300mm×300mm, and the weight of a single casting weight is about 3T.

[0016] In the above step 6), the locking device is a latch, and four of the latches connect two corresponding casting weights at upper and lower positions.

[0017] The advantages of the present invention compared with the prior art are:

[0018] 1. This technical solution optimizes the design of the parting surface and the pouring system, adopts a three-parting-surface four-opening method, improves the convenience of sand pounding and the accuracy of box closing, ensures the stable rise of the molten iron level, and helps reduce the oxidation slag defects caused by turbulence;

[0019] 2. This technical solution increases the shrinkage feeding capacity of the molten iron during the solidification of the casting and reduces the shrinkage tendency of the gray iron cylinder body through the optimized design of the riser, the optimized design of the chill, and the optimized design of the gas outlet. The more exhaust channels can make the cavity exhaust smooth, reduce the occurrence of porosity defects, and accelerate the solidification speed of thick and large parts;

[0020] 3. This technical solution ensures the stable and reliable position of the flask by optimizing the layout of the iron weights and the design of the lock box, effectively eliminating the risk of casting fire caused by lifting the flask when the molten iron is lifted. It also fixes the casting in the length and width directions to avoid deformation of the casting.

[0021] 4. This technical solution is rationally designed and effectively solves the problems of large shrinkage tendency and frequent porosity defects in cylinder blocks, stabilizes the production of large cylinder block castings, and has high process assurance and stable casting quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the design principle of the parting surface of the present invention;

[0023] Figure 2 This is a schematic structural diagram of the pouring system of the present invention;

[0024] Figure 3 This is the front view of the riser gas outlet design of the present invention;

[0025] Figure 4This is a side cross-sectional view of the riser outlet of the present invention;

[0026] Figure 5 This is a schematic diagram of the chiller distribution of the cylinder block of the present invention;

[0027] Figure 6 This is a front view of the cylinder block casting weight arrangement of the present invention;

[0028] Figure 7 This is a left side view of the cylinder block casting weight arrangement of the present invention;

[0029] Figure 8 This is a simplified structural diagram of the cylinder block pouring cup arrangement scheme of the present invention. DETAILED DESCRIPTION

[0030] The following is a combination of the embodiments of the present invention Figure 1-8 The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] It should be noted that, in this document, unless otherwise stated, it should be understood that the terms "center," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate positions or relationships based on those shown in the accompanying drawings. These are intended only to facilitate the description of the present invention and simplify the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] As used herein, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, the phrase "comprising a..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the elements.

[0033] The casting method of large diesel engine cylinder block, the specific optimization steps are as follows:

[0034] 1) Parting surface design: A four-opening mold with the lower plane facing upward is adopted, including parting surface 1, parting surface 2 and parting surface 3. The selection of the three parting surfaces fully considers the convenience of pounding sand and the accuracy of box assembly. Figure 1 As shown;

[0035] 2) Casting system design: such as Figure 2 As shown, an open bottom pouring rain gating system with a filter 4 is used. The sprues 5 on both sides of the mold are made of Φ100mm ceramic tubes. The runners 6 connected to the sprues 5 are of a rectangular cross-section arranged around the cylinder body. Several filters 4 are provided on the runners 6, and the ingates 7 connected to the runners 6 through the filters 4 are made of Φ40mm porcelain tubes. The sprues 5 serve as a flow-blocking section. The molten iron flows from the sprues 5 to the ingates 6, and then passes through the filters 4 and is dispersedly introduced from the lowest surface of the cavity. In combination with the open ingates, the molten iron level rises steadily, which helps to reduce the oxidation slag defects caused by turbulence.

[0036] 3) Riser design: Figure 3-4 As shown, a plurality of Φ280mm insulation risers 8 are provided at the highest point of the upper plane of the mold and distributed on the lower plane of the air inlet side 9, the lower plane of the exhaust side 10 and the lower plane of the free end 11. Each insulation riser 8 is heightened to increase the shrinkage-feeding capacity of the molten iron during the solidification of the casting and reduce the shrinkage tendency of the gray iron cylinder body; two cavity air outlets 14 are distributed on each rib 12 and stuffing box hole 13 on the upper plane of the mold; a sand core air outlet hole 16 is provided in the center of the stuffing box hole core 15, and each sand core air outlet hole 16 is a Φ130mm through-exhaust channel for enlarging the core exhaust; a sand core air outlet hole 2 18 is provided in the center of the bolt hole core 17, and more exhaust channels can be To ensure smooth cavity exhaust and reduce the occurrence of pore defects; specifically, there are fourteen insulation risers 8, of which six are provided on the air inlet side 9 and the exhaust side 10 of the lower plane, and two are provided on the free end 11; specifically, the insulation riser 8 is raised by 150mm on the basis of the original height, wherein the original height of the insulation riser 8 is 400mm, the diameter of the cavity air outlet 14 is Φ20mm, the diameter of the sand core air outlet 16 is Φ130mm, and the diameter of the sand core air outlet 2 18 is Φ20mm, thereby increasing the exhaust of the core; wherein, there are twelve cavity air outlet holes 14, and the diameter of the cavity air outlet hole 14 is designed to be Φ20mm. If it is too large, a thermal node will be formed, causing shrinkage;

[0037] 4) Cold iron design: Figure 5As shown, a chill 19 is arranged on the surface of the cylinder body wall in the cavity where the wall thickness is greater than 100 mm, and the thickness of the chill 19 is designed to be 2 / 3 of the wall thickness of the cooled area. The chill 19 includes a flat chill and a form-fitting chill. Specifically, the dimensions of the chill 19 are 200 mm × 100 mm × 70 mm, and the gap between the chills 19 is between 20 and 30 mm. This design is used to accelerate the solidification rate of these thick areas, mainly including the inside of the stuffing box hole, the inside and upper plane of the cylinder bore, and the exhaust side.

[0038] 5) Iron weight arrangement plan: Figure 6 As shown, there are eight casting weights 21 for compacting the flask 20, and the eight casting weights 21 are distributed in two groups of four, with the spacing between adjacent casting weights 21 not exceeding 1000 mm. Two casting weights 21 in the middle of the flask 20 are centered along the length of the mold 22 to prevent the molten iron from floating; the other two casting weights 21 are located at the edges of the mold 22. Specifically, the specifications of the casting weights 21 are 4700 mm × 300 mm × 300 mm, and the weight of a single casting weight 21 is about 3 tons.

[0039] 6) Sand box locking design: such as Figure 7 As shown, a locking device is used to fix the casting weights 21 corresponding to the upper and lower positions to the rear lock box, and the angle iron 24 used to tightly fix the corners of the flask 20 is fixed on the casting weight 21 toward the side of the flask 20; specifically, the locking device is a latch 23, and the four latches 23 connect the two casting weights 21 corresponding to the upper and lower positions. The evenly distributed two layers of casting weights 21 are used in conjunction with the latch 23 to effectively prevent the flask 20 from lifting, which can effectively eliminate the risk of casting fire caused by lifting the molten iron box, and fix the casting in the length and width directions to avoid deformation of the casting.

[0040] 7) Pour cup design: such as Figure 8 As shown, two 5T quantitative pouring cups 25 and two 20T ladles 26 are used for simultaneous pouring from both sides of the sand box 20. During pouring, it is ensured that the weight and temperature of the molten iron in the two ladles 26 are basically the same, so as to ensure that after the molten iron in the two ladles 26 meet at the bottom of the cavity, there will be no defects such as cold shut due to the temperature difference of the molten iron, thereby ensuring the quality of the molten iron meeting at the bottom of the cavity.

[0041] Melting process:

[0042] Charge ratio: pig iron 20%, scrap steel 60%, recycled material 20%;

[0043] Chemical composition of molten iron (%): C: 3.1-3.2; Si: 1.3-1.4; Mn: 0.8-0.9; P < 0.1; S: 0.06-0.07;

[0044] Pouring temperature: pouring cup temperature 1300 ~ 1320 ℃

[0045] The molten iron is allowed to stand at high temperature before being taken out of the furnace to fully melt the alloy elements. The temperature is 1520-1530℃ and it is allowed to stand for 5-10 minutes. This can effectively improve the intrinsic quality of the casting and avoid shrinkage and cold shut defects.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0047] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A large diesel engine cylinder block casting method, characterized in that The specific optimization steps are as follows: 1) Parting surface design: a four-opening mold with the lower plane facing upward and including parting surface one (1), parting surface two (2) and parting surface three (3); 2) Design of pouring system: an open bottom pouring rain pouring system with a filter (4) is adopted, the sprues (5) on both sides of the mold adopt Φ100mm ceramic tubes, the runner (6) connected to the sprue (5) is a rectangular cross section arranged around the cylinder body, a plurality of filters (4) are provided on the runner (6), and the ingrown (7) connected to the runner (6) through the filter (4) is a Φ40mm porcelain tube; the sprue (5) serves as a flow-blocking section, the molten iron flows from the sprue (5) to the ingrown (6), and then passes through the filter (4) and is dispersedly introduced from the lowest surface of the cavity, and cooperates with the open ingrown gate to make the molten iron liquid level rise steadily; 3) Riser design: multiple Φ280mm heat-insulating risers (8) are provided at the highest point of the upper plane of the mold and distributed on the lower plane of the air inlet side (9), the lower plane of the exhaust side (10) and the lower plane of the free end (11), and each heat-insulating riser (8) is heightened; two cavity air outlet holes (14) are distributed on each rib (12) and stuffing box hole (13) of the upper plane of the mold; wherein a sand core air outlet hole (16) is provided in the center of the stuffing box hole core (15), and each sand core air outlet hole (16) is a Φ130mm through-going exhaust channel for enlarged core exhaust; a sand core air outlet hole (18) is provided in the center of the bolt hole core (17); 4) Chill design: Chill (19) is arranged on the surface of the cylinder body with a wall thickness greater than 100 mm in the cavity, and the thickness of the chill (19) is designed according to 2 / 3 of the wall thickness of the cooled part, wherein the chill (19) includes a flat chill and a contoured chill; 5) Iron weight arrangement scheme: There are eight casting iron weights (21) for pressing the sand box (20), and the eight casting iron weights (21) are distributed in two groups of four in each group. The distance between adjacent casting iron weights (21) is not more than 1000 mm. Two casting iron weights (21) in the middle of the sand box (20) are used to prevent the molten iron from floating up and are distributed in the middle along the length direction of the casting mold (22); the other two casting iron weights (21) are distributed at the edge of the casting mold (22); 6) Sand box locking design: A locking device is used to fix the corresponding casting weights (21) at the upper and lower positions to the rear locking box, and an angle iron (24) is fixed on the side of the casting weights (21) facing the sand box (20) to tightly fix the edges and corners of the sand box (20); 7) Design of pouring cup: Two 5T quantitative pouring cups (25) and two 20T ladles (26) are used to pour from both sides of the sand box (20) at the same time. During pouring, it is ensured that the weight and temperature of the molten iron in the two ladles (26) are basically the same, so as to ensure that the molten iron in the two ladles (26) will not form defects such as cold shut due to the temperature difference of the molten iron after meeting at the bottom of the cavity.

2. The large diesel engine cylinder block casting method according to claim 1, characterized in that: In the above step 3), there are fourteen thermal insulation risers (8), of which six are provided on the air inlet side (9) and the exhaust side (10) of the lower plane, and two are provided on the free end (11).

3. The large diesel engine cylinder block casting method according to claim 2, characterized in that: The heat-insulating riser (8) is raised by 150 mm on the basis of the original height, the diameter of the cavity air outlet (14) is Φ20 mm, the diameter of the sand core air outlet hole 1 (16) is Φ130 mm, and the diameter of the sand core air outlet hole 2 (18) is Φ20 mm.

4. The large diesel engine cylinder block casting method according to claim 1, characterized in that: In the above step 4), the size of the cold iron (19) is 200mm×100mm, and the gap of the cold iron (19) is between 20 and 30mm.

5. The large diesel engine cylinder block casting method according to claim 1, characterized in that: In the above step 5), the specification of the casting weight (21) is 4700mm×300mm×300mm, and the weight of a single casting weight (21) is about 3T.

6. The large diesel engine cylinder block casting method according to claim 1, characterized in that: In the above step 6), the locking device is a latch (23), and four latches (23) connect two corresponding casting weights (21) at upper and lower positions.

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