Casting forming method for cylinder block of large diesel engine

Abstract

According to the large diesel engine cylinder block casting forming method, through optimal design of a parting surface, an optimal design of a pouring system, an optimal design of a dead head, an optimal design of gas outlet, an optimal design of a chilling block and an optimal design of a lock box in sequence, sand pounding convenience and box closing accuracy are ensured, the oxidation slag inclusion defect caused by turbulent flow is reduced, and the service life of the cylinder block is prolonged. The air hole defect is reduced, the solidification speed of the thick and large part is high, the position of the sand box is stable and reliable, the problems that the air cylinder body is large in shrinkage porosity tendency and frequent in air hole defect are effectively solved, the production of large air cylinder body castings is stabilized, the process guarantee is high, and the casting quality is stable.

Description

Technical Field

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

[0002] As one of the key components of diesel engines, the cylinder block of a large diesel engine must have high quality and high precision. The material grade of a certain type of diesel engine cylinder block is HT250, with a gross weight of 34.5t, a main wall thickness of 60-80mm, a size of approximately 4100mm×2065mm×2170mm, and a liquid weight of 40.5t. It adopts an open bottom pouring rain pouring system with a filter facing up, with 14 Φ280 insulation top risers, and sets cold irons on the cylinder bore surface, sleeve box and other parts. The cold iron thickness is 60-80mm, and the cold iron material is HT200. Sand cores are set on the top surface of each bolt hole core and stuffing box hole core to vent; However, due to the large and uneven wall thickness of the cylinder block, complex structure, large differences in solidification time in different areas, and the high sensitivity of special areas of gray cast iron, shrinkage defects exist on the lower plane; pores often appear on the lower plane and the edge of the window, and the pores contain a small amount of slag, which seriously affects the surface quality of the casting. Therefore, it is necessary to improve the above problems. 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 pounding sand and the accuracy of box assembly by optimizing the design of the parting surface, the pouring system, the riser, the air outlet, the cold iron and the lock box in sequence, reduces the oxidation slag defects caused by turbulence, reduces the generation of pore defects, and has a fast solidification speed in thick and large parts, and the position of the sand box is stable and reliable, which effectively solves the problems of large shrinkage tendency and frequent pore 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 casting method for a large diesel engine cylinder block, 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) Design of pouring system: an open bottom pouring rain pouring system with a filter is adopted. The sprues on both sides of the mold adopt Φ100mm ceramic tubes. The runners connected to the sprues are rectangular sections arranged around the cylinder body. Several filters are arranged on the runners and the entgates connected to the entrants through the filters are Φ40mm porcelain tubes. The sprues serve as flow-blocking sections. The molten iron flows from the sprues to the entrants and then dispersedly introduced from the lowest surface of the cavity through the filters. With the open entrants, the molten iron level rises steadily.

[0007] 3) Riser design: multiple Φ280mm insulation risers are used, which are located at the highest point of the upper plane of the mold and distributed on the lower plane of the air inlet side, the lower plane of the exhaust side and the lower plane of the free end. Each insulation riser is heightened; two cavity air outlets are distributed at each rib and stuffing box hole on the upper plane of the mold; a sand core air outlet hole 1 is provided in the center of the stuffing box hole core, and each sand core air outlet hole 1 is a Φ130mm through-exhaust channel for enlarged core exhaust; a sand core air outlet hole 2 is provided in the center of the bolt hole core;

[0008] 4) Chill design: Chill is arranged on the surface of the cylinder body with a wall thickness greater than 100mm in the cavity, and the thickness of the chill is designed according to 2 / 3 of the wall thickness of the cooled part. The chill includes flat chill and conformal chill;

[0009] 5) Iron weight arrangement plan: There are eight casting iron weights for pressing the sand box, and the eight casting iron weights are distributed in two groups of four in each group. The distance between adjacent casting iron weights is not more than 1000mm. The two casting iron weights in the middle of the sand box to prevent the molten iron from floating are distributed in the middle along the length direction of the mold; the other two casting iron weights are distributed at the edge 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 then lock the box, and fix the angle irons used to tightly fix the edges and 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, ensure that the weight and temperature of the molten iron in the two ladles are basically consistent, so as to ensure that after the molten iron in the two ladles meets at the bottom of the cavity, there will be no defects such as cold shut due to the temperature difference of the molten iron.

[0012] In the above step 3), there are fourteen thermal insulation risers in total, of which six are arranged on the air inlet side and the exhaust side of the lower plane, and two are arranged 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 cold iron is 200 mm×100 mm, and the gap of the cold iron is between 20 and 30 mm.

[0015] In the above step 5), the specification of the casting weight is 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, and adopts a three-parting surface and four-opening method to improve the convenience of pounding sand and the accuracy of closing the box, ensuring that the molten iron level rises steadily, which is conducive to reducing the oxidation slag defects caused by turbulence;

[0019] 2. This technical solution increases the shrinkage-compensation 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 chiller and the optimized design of the gas outlet. More exhaust channels can make the cavity exhaust unobstructed, reduce the generation of pore defects, and accelerate the solidification speed of thick and large parts;

[0020] 3. This technical solution ensures the stable and reliable position of the sand box by optimizing the layout of the iron pressure and the design of the lock box, which can effectively eliminate the quality risk of casting fire caused by lifting the iron liquid box, and fix the casting in the length and width direction to avoid deformation of the casting;

[0021] 4. This technical solution is reasonably designed, which 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 It is a schematic diagram of the pouring system structure of the present invention;

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

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

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

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

[0028] Figure 7 It is a left view of the arrangement of the casting weights for the cylinder block of the present invention;

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

[0030] The following will be combined with 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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", "inside", "outside", etc., indicating positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc., are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0032] In this document, the terms "comprises", "comprising" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further limitations. The elements defined by the sentence "comprising a ..." do not exclude the presence of other identical elements in the process, method, article or device comprising 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 a 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: Figure 2 As shown, an open bottom pouring rain gating system with a filter 4 is adopted, the sprue 5 on both sides of the mold adopts a Φ100mm ceramic tube, the runner 6 connected with the sprue 5 is a rectangular section arranged around the cylinder body, a plurality of filters 4 are arranged on the runner 6, and the ingates 7 connected with the runner 6 through the filters 4 are Φ40mm porcelain tubes; the sprue 5 is used as a flow-blocking section, and the molten iron flows from the sprue 5 to the ingates 6, and then dispersedly introduced from the lowest surface of the cavity through the filter 4, and cooperates with the open ingates to make the molten iron level rise steadily, which is conducive to reducing the oxidation slag defects caused by turbulence;

[0036] 3) Riser design: Figure 3-4 As shown, a plurality of 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. Each heat-insulating riser 8 is heightened to increase the shrinkage compensation 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 at each rib 12 and stuffing box hole 13 on the upper plane of the mold; wherein the stuffing box hole core 15 is centrally penetrated with a sand core air outlet hole 16, 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 centrally penetrated on the bolt hole core 17, and more exhaust channels can be Make the cavity venting smooth and reduce the generation of pore defects; specifically, the insulation riser 8 has a total of fourteen, among which the air inlet side 9 and the exhaust side 10 of the lower plane are each provided with six, and the free end 11 is provided with two; specifically, the insulation riser 8 is increased 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 vent hole 14 is Φ20mm, the diameter of the sand core vent hole 16 is Φ130mm, and the diameter of the sand core vent hole 2 18 is Φ20mm, and the venting of the core is increased; wherein, the cavity vent hole 14 is provided with twelve, and the diameter of the cavity vent hole 14 is designed to be Φ20mm. If it is too large, a heat node will be formed to cause 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 thickness is greater than 100 mm, 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 plane chill and a conforming chill; specifically, the size of the chill 19 is 200 mm×100 mm×70 mm, and the gap of the chill 19 is between 20 and 30 mm. This design is used to accelerate the solidification speed of these thick parts, mainly including the inner side of the stuffing box hole, the inner side and upper plane of the cylinder hole, the exhaust side, etc.;

[0038] 5) Iron weight arrangement plan: Figure 6 As shown, there are eight casting weights 21 for pressing the sand box 20, and the eight casting weights 21 are distributed in two groups, four in each group, and the distance between adjacent casting weights 21 is no more than 1000mm. Two casting weights 21 in the middle of the sand box 20 are used to prevent the molten iron from floating and are distributed in the middle along the length direction of the casting mold 22; the other two casting weights 21 are distributed at the edge of the casting mold 22; specifically, the specifications of the casting weights 21 are 4700mm×300mm×300mm, and the weight of a single casting weight 21 is about 3T;

[0039] 6) Sand box locking design: Figure 7 As shown, a locking device is used to fix the casting weights 21 corresponding to the upper and lower positions and connect the rear lock box, and an angle iron 24 used to tightly fix the edges and corners of the sand box 20 is fixed on the casting weight 21 facing the sand box 20; specifically, the locking device is a latch 23, and four of the 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 latches 23 to effectively prevent the sand box 20 from lifting up, and can effectively eliminate the risk of casting fire quality caused by lifting the iron liquid box, and the casting is fixed in the length and width directions to avoid deformation of the casting;

[0040] 7) Pour cup design: 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 consistent, 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: 20% pig iron, 60% scrap steel, 20% recycled materials;

[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, which 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 invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0047] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description 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 may also be appropriately combined to form other implementation modes 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 box mold is designed with the lower plane facing upward and includes a parting surface 1 (1), a parting surface 2 (2) and a parting surface 3 (3); 2) Design of pouring system: an open bottom pouring rain pouring system with a filter (4) is adopted, the sprue (5) on both sides of the mold adopts a Φ100 mm ceramic tube, the cross runner (6) connected to the sprue (5) is a rectangular cross section arranged around the cylinder body, a plurality of filters (4) are arranged on the cross runner (6), and the inner runner (7) connected to the cross runner (6) through the filter (4) is a Φ40 mm ceramic tube; the sprue (5) serves as a flow-blocking section, and the molten iron flows from the sprue (5) to the cross runner (6), and then passes through the filter (4) and is dispersedly introduced from the lowest surface of the cavity, and cooperates with the open inner gate to make the molten iron level rise steadily; 3) Riser design: multiple Φ280 mm 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 at 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 Φ130 mm 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: a chill (19) is arranged on the surface of the cylinder body in the cavity where the wall thickness is greater than 100 mm, 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: A total of eight casting iron weights (21) are provided for pressing the sand box (20), and the eight casting iron weights (21) are distributed in two groups, with four iron weights in each group, and the distance between adjacent casting iron weights (21) is not greater than 1000 mm. Two casting iron weights (21) in the middle of the sand box (20) for preventing the molten iron from floating are centrally distributed 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 casting weights (21) corresponding to the upper and lower positions to lock the box, and an angle iron (24) is fixed on the casting weight (21) facing the sand box (20) to tightly fix the edges and corners of the sand box (20); 7) Pouring cup design: 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 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.

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 distributed positions.

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