Molten iron filling system for marine medium-speed diesel engine body

Abstract

The invention provides a marine medium-speed diesel engine body molten iron mold filling system, and belongs to the technical field of diesel engine production. When the diesel engine body is subjected to mold filling, the surface of a casting mold cylinder faces downwards, and the diesel engine body molten iron mold filling system is an open bottom pouring type molten iron mold filling system and comprises a pouring cup, a straight pouring gate, a transverse pouring gate and an inner pouring gate which are connected in sequence; the ingate is connected with a flow gate, and the flow gate is arranged at the edge position of a downward air cylinder hole in the casting mold and is communicated with an inner cavity of the casting mold; the sectional area ratio of three units of a straight pouring gate, a transverse pouring gate and an inner pouring gate is 1: 2: 2, and the flow speed of molten iron in the inner pouring gate is controlled to be smaller than or equal to 100 cm / s by combining the mold filling time and the liquid level rising speed; the pouring cup is a quantitative pouring cup with a plug pulling mechanism. According to the method, molten iron mold filling is stable, molten iron turbulence is reduced, self-feeding of the ductile iron casting is facilitated, the phenomena of shrinkage porosity, sand inclusion, slag inclusion and the like of machine body shrinkage cavities are reduced, and the inclusion defects of similar diesel engine bodies on cylinder hole surfaces, crankshaft holes and cam shaft holes are overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of diesel engine production, and in particular relates to a liquid iron filling system for a medium-speed marine diesel engine body. Background Art

[0002] Marine medium-speed diesel engines are mainly used for the main power or auxiliary power generation of ships. They are also used for emergency power generation of nuclear power units, fixed power generation on land, and mobile power stations.

[0003] The diesel engine is one of the important components of the ship. The performance of the diesel engine directly affects the performance and safety of the ship. The fuselage, as the main component of the diesel engine, is the premise for ensuring the normal operation of the diesel engine. The diesel engine fuselage is mostly a casting, and the quality requirements are very high. There are thick and large hot spots in the cylinder hole, main bearing bolt hole, main bearing shell surface, transverse bolt hole, cylinder head bolt hole, bottom plate and other parts of the fuselage, which are prone to casting shrinkage holes and shrinkage defects, affecting the assembly and use of the diesel engine. Therefore, a more reasonable casting process must be designed during the casting process, and the molten iron filling system plays a very important role in casting production.

[0004] The molten iron filling system is a general term for a series of channels that guide the liquid metal into the mold cavity. It is a series of channels opened in the mold to fill the mold cavity and the riser. The filling capacity of the liquid metal is affected by factors such as the fluidity of the metal, the properties of the mold, the pouring conditions, and the structure of the casting. It is a comprehensive reflection of various factors. Under certain pouring conditions, the filling capacity of the molten metal is closely related to its average flow velocity v in the mold cavity and the time t from when it enters the mold cavity until it stops flowing. Appropriate flow velocity v and pouring time t are the basic conditions to ensure good filling of the mold. Therefore, in the process design, it is necessary to comprehensively consider the comprehensive influence of the fluidity of the metal, the properties of the mold, the pouring conditions and the structure of the casting, and then make a reasonable design of the molten iron filling system.

[0005] Generally, the design of the iron filling system for medium-speed diesel engine fuselages varies greatly according to the structure and complexity of the fuselage castings. For inline fuselages, vertical and horizontal solutions are generally used; while for V-type fuselages, bottom pouring and stepped pouring are generally used. A reasonable iron filling system will ensure that the molten metal has enough energy to overcome the various resistances encountered during the filling process and minimize the heat loss of the molten metal before entering the mold cavity. Therefore, in the casting process of the diesel engine fuselage, the design of the iron filling system has a great influence on the quality of the casting, and the iron filling system is an important link in the mold filling system.

[0006] For different diesel engine bodies, the design of the molten iron filling system has a key impact on the quality of the body. Improper settings of the molten iron filling system directly lead to various casting defects such as sand blasting, sand inclusion, slag inclusion in the expansion tube hole, and inclusion in key parts of the body, such as the camshaft hole, the bottom edge of the cylinder hole, and the crankshaft hole, which will seriously cause the casting to be scrapped. Therefore, a more reasonable molten iron filling system must be designed according to the body structure and technical requirements, which is of great significance to improving the quality of castings and reducing production costs.

[0007] Now, based on the development and production tasks of the X52 project, it is necessary to realize the localization of the MPV diesel engine body. The body of this type of diesel engine has a compact outline, thin overall wall thickness, a large difference in local wall thickness, a complex internal and external structure, and a pouring weight of about 8 tons. The body density requirements are high, and key parts need to be inspected by radiography. Casting defects are not allowed on the crankshaft, camshaft, and cylinder bore surface. During the pouring process, it is necessary to ensure that the molten iron is filled steadily and the filling time is avoided to be too long. The casting process design is relatively strict, especially the design of the molten iron filling system is very important. However, the existing similar diesel engine bodies are not fully and reasonably designed. The molten iron filling is not stable enough, there are problems such as air entrainment and sand flushing, and there are often mixed defects on the lower edge of the lower cylinder hole of the body, the main bearing hole, and the camshaft hole. In order to ensure the quality of this type of diesel engine body, on the basis of fully understanding and mastering the general laws of the molten iron filling system, according to the specific conditions of the MPV body, it is necessary to propose a new molten iron filling system for the MPV diesel engine body. Summary of the invention

[0008] The technical problem solved by the present invention is as follows: a molten iron filling system for a medium-speed marine diesel engine body is provided. The purpose of the present invention is to overcome the problems in the prior art and to propose a new design for an MPV diesel engine body. The smoothness of molten iron filling is improved by the reasonable introduction position and size of the inner runner, and the risk of secondary oxidation slag inclusion caused by turbulence is reduced. The quality of the molten iron is improved by the design of a controllable closed quantitative pouring cup and a slag-avoiding molten iron filling system, and the inclusion defects in key parts of the body are reduced. The inclusion defects that existed in the cylinder bore surface, crankshaft hole, and camshaft hole of the diesel engine body in the past are solved, so as to ensure the successful development of this type of body and provide a certain basis for the design and improvement of subsequent molten iron filling systems for diesel engine bodies.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A marine medium-speed diesel engine fuselage iron liquid filling system, wherein the diesel engine fuselage is filled with the casting cylinder facing downward, and the diesel engine fuselage iron liquid filling system adopts an open bottom injection iron liquid filling system, including a pouring cup, a sprue, a runner, and an ingates connected in sequence;

[0011] The ingates are connected to the ingates, which are arranged at the edge of the cylinder bore facing downwards on the casting mold and communicate with the inner cavity of the casting mold;

[0012] The cross-sectional area ratio of the three units of the sprue, runner and ingates is ∑F 直 :∑F 横 :∑F 内 =1:2:2, combined with the filling time and the liquid level rising speed, the molten iron flow rate in the ingrate is controlled at ≤100cm / s;

[0013] The pouring cup is a quantitative pouring cup with a plug-pulling mechanism.

[0014] To further limit the above solution, the cross-sectional area calculation formula of the sprue is:

[0015]

[0016] Among them, G is the pouring weight.

[0017] μ—flow rate coefficient, take 0.46

[0018] Pouring time t Where s1 is the coefficient, which is 1.9, and δ is the wall thickness of the main part of the casting;

[0019] Review of metal liquid level rising speed:

[0020] V 上升 =C / t, C is the casting height, t is the pouring time;

[0021] To meet the requirements of molten iron rising speed, V 上升 10~20mm / s;

[0022] Average static head Where C is the height of the casting, and H0 is the static pressure head of the molten metal;

[0023] The cross-sectional areas of the runner and the ingates are calculated based on the proportional relationship of the cross-sectional areas of the three units.

[0024] As a further limitation of the above solution, the inlet of the ingrowth is overlapped at a lower middle position in the height direction of the cross runner.

[0025] As a further limitation of the above solution, the straight runner adopts a variable diameter straight runner.

[0026] To further limit the above scheme, the pouring cup includes a pouring cup body, a liquid outlet is provided at the bottom of the pouring cup body, a plug for closing and opening the liquid outlet is provided inside the pouring cup body, and the lower end of the plug is a spherical structure.

[0027] As a further limitation of the above scheme, the sprue, runner and inner runner are all made of ceramic tubes of corresponding specifications.

[0028] As a further limitation of the above scheme, the diesel engine body is an MPV type diesel engine body.

[0029] The advantages of the present invention compared with the prior art are:

[0030] 1. The casting process of this scheme adopts a bottom-pouring iron liquid filling system with the cylinder facing downward. By arranging the structure of the filling system and controlling the speed of the metal liquid filling the mold and the time required to fill the mold, the iron liquid can be filled smoothly, with little impact on the mold and core, little metal oxidation, and is conducive to the discharge of gas in the mold cavity; the turbulence of the iron liquid is reduced, turbulence and scouring of the mold are avoided, which is conducive to the self-compensation of the ductile iron parts, and reduces the shrinkage of the fuselage, sand and slag inclusions, etc.

[0031] 2. This solution can ensure that the linear speed of the molten metal will not be too high when it enters the mold cavity, avoiding splashing, scouring the mold wall or sand mold; ensuring that the metal liquid level in the mold has a sufficient rising speed to avoid defects such as sand inclusion scars, wrinkles, cold shut, etc.

[0032] 3. This solution uses the first slag avoidance function in the quantitative pouring cup and designs a variable diameter sprue with slag avoidance capability at the connection part with the pouring cup. The sprue diameter controls the flow rate and flow of the molten metal to achieve stable filling and control the flow rate of the inner runner outlet, thus realizing the second slag avoidance of the sprue, thereby effectively preventing slag from entering the casting mold to cause slag inclusion defects.

[0033] 4. This solution can control the temperature distribution of the casting during solidification, reducing or eliminating defects such as shrinkage cavities, shrinkage, cracks and deformation of the casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A structural diagram of the diesel engine body iron liquid filling system provided by the present invention;

[0035] Figure 2 The bottom structure diagram of the diesel engine body molten iron filling system provided by the present invention;

[0036] Figure 3 It is a schematic diagram of the structure of the overlap between the ingates and runners in the present invention;

[0037] Figure 4 It is a schematic diagram of the structure of the pouring cup in the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0039] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0040] See also Figure 1-4 , details of the embodiments of the present invention.

[0041] Embodiment: A molten iron filling system for a medium-speed marine diesel engine body. In this embodiment, the diesel engine body is an MPV diesel engine body. The cylinder of the diesel engine body faces downward during the filling process. The molten iron filling system for the diesel engine body adopts an open bottom-injection molten iron filling system, including a pouring cup 1, a sprue 2, a runner 3, and an inner runner 4 connected in sequence. Figure 1 shown.

[0042] 1. Molten iron introduction position

[0043] In order to smoothly introduce molten iron into the mold cavity, a bottom pouring ingrate is used. Because the ingrate is submerged during mold filling, the molten metal in the mold flows smoothly, without splashing, and metal oxidation is less, which can avoid the formation of recycled slag during the pouring process. At the same time, in order to avoid the formation of contact heat nodes due to the large difference in thickness between the ingrate and the casting wall, according to the structural characteristics of the fuselage, refer to Figure 2 As shown, the inner gate is set at the edge of the cylinder bore facing downward on the casting mold and is connected to the inner cavity of the casting mold; the scheme introduced from the edge of the cylinder bore has a vertical upward wall thickness around the cylinder bore, which is conducive to the rise of molten iron and reduces the occurrence of defects.

[0044] 2. This system adopts an open bottom pouring molten iron filling system. The straight runner 2 adopts a variable diameter straight runner. The straight runner is a flow-blocking section, and the cross runner has the largest cross-sectional area. While meeting the large-capacity transportation of molten iron, it can ensure that the molten iron is filled smoothly and that the slag in the molten iron fully floats in the cross runner to avoid entering the mold cavity.

[0045] The cross-sectional area ratio of the three units of the sprue 2, the runner 3 and the ingrate 4 is ∑F直 :∑F 横 :∑F 内 =1:2:2, combined with the filling time and the liquid level rising speed, the molten iron flow rate of the ingrate 4 is controlled to be ≤100cm / s. In this embodiment:

[0046] a. The cross-sectional area calculation formula of sprue 2 is:

[0047]

[0048] Where, G is the weight of the cast iron liquid, where G = 8000 kg;

[0049] μ—flow rate coefficient, take 0.46

[0050] Pouring time t: Among them, s1 is the coefficient, which is 1.9; δ is the wall thickness of the main part of the casting, which is 10mm;

[0051] Review of metal liquid level rising speed:

[0052] V 上升 =C / t=1120÷82≈13.7 (mm / s), where C is the casting height and t is the pouring time;

[0053] Meet the requirements of molten iron rising speed, V 上升 10~20mm / s;

[0054] Average static head Where C is the height of the casting, and H0 is the static pressure head of the molten metal;

[0055]

[0056] If there are 2 sprues, the single cross-sectional area is:

[0057] Two φ70 sprues are actually selected, with a single cross-sectional area of ​​38.5cm 2 .

[0058] b. Cross-sectional area of ​​​​the ingate

[0059] According to the proportion of each unit in the molten iron filling system:

[0060] ∑F 内 =38.5×2×2=154cm 2

[0061] Actually, 22 ingates are used.

[0062] The cross-sectional area of ​​a single φ30 gate is 7.07 cm 2

[0063] ∑F 内 =22×7.07=155.54cm 2

[0064] Average flow velocity verification of ingate outlet:

[0065]

[0066] According to practical experience, the flow rate of molten iron at the pouring gate outlet is controlled at ≤100cm / s.

[0067] To further increase the skimming capacity of the hot metal filling system, refer to Figure 3 As shown, the inlet of the inner runner 4 overlaps the middle lower position in the height direction of the runner 3. The advantage is that it can ensure that the dirty molten iron at the beginning of pouring enters the mold cavity, and prevent the slag in the subsequent molten iron from entering the mold cavity.

[0068] c. Cross-sectional area of ​​runner

[0069] According to the proportion of each unit in the molten iron filling system:

[0070] ∑F 横 =75.1×2=150.2cm 2

[0071] The actual cross-sectional size is φ100 circular runner, and the cross-sectional area of ​​a single runner is 78.5cm 2 There are two runners in total, with a cross-sectional area of ​​78.5×2=157cm 2 .

[0072] 3. The pouring cup 1 is a quantitative pouring cup with a plug-pulling mechanism.

[0073] See also Figure 4 As shown, the pouring cup 1 includes a pouring cup body 1-1, a liquid outlet 1-2 is provided at the bottom of the pouring cup body 1-1, a plug 1-3 for closing and opening the liquid outlet 1-2 is provided inside the pouring cup body 1-1, and the lower end of the plug 1-3 is a spherical structure.

[0074] This embodiment adopts a quantitative pouring cup with a plug-pulling mechanism. When pouring, first pour 10T of molten iron into the pouring cup. After the slag fully floats, the plug-pulling mechanism is controlled to open the plug. Since there is a high liquid level in the pouring cup, the slag always floats on the surface and is not easy to enter the cavity. After the cavity is filled with pouring, the plug is used to close it, so that the remaining inclusions in the pouring cup remain in the pouring cup.

[0075] In this embodiment, the sprue 2, the runner 3, and the inner runner 4 are made of φ30, φ70, φ100 tubular ceramic tubes that can be purchased on the market.

[0076] The technical solution of the present invention has the following key advantages:

[0077] 1. High flow, low flow rate and stable ingrate design

[0078] Through calculation and filling simulation, a turbulence-free structure with smooth filling and uniform ingates is designed. At the same time, the molten iron flow rate in the ingates is controlled to be less than 100 mm / s in combination with the filling time and the liquid level rising speed.

[0079] 2. Variable diameter straight runner design

[0080] A variable diameter sprue with slag avoidance capability is designed at the connection with the pouring cup. The sprue diameter is used to control the velocity and flow rate of the molten metal, thereby achieving smooth filling, controlling the entrapment outlet velocity, and realizing the second slag avoidance of the sprue.

[0081] 3. Design of controllable quantitative pouring cup with plug-pulling mechanism

[0082] Combined with the self-feeding ability of ductile iron, according to the size, wall thickness and pouring weight of this type of diesel engine body, a multiple-feeding process is designed to give full play to the graphitization expansion of ductile iron and improve the density of thick and large parts of the body. Combined with the requirements of multiple-feeding process, a quantitative pouring cup with a plug-pulling mechanism is designed to achieve the first slag avoidance function in the pouring cup.

[0083] In summary, the molten iron filling system of the present invention is used in the actual production process, has strong operability, the molten iron fills the mold smoothly during the pouring process, the shrinkage compensation is sufficient, and the casting quality is greatly improved. This molten iron filling system is used in the casting process of the fuselage of medium and high-speed marine diesel engines, realizes stable molten iron filling, reduces molten iron turbulence, is conducive to the self-shrinkage compensation of ductile iron parts, and reduces shrinkage cavities, shrinkage, sand and slag inclusions, etc.

[0084] 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.

[0085] 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 can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. Iron liquid filling system for medium speed marine diesel engine body, Features: The cylinder face of the diesel engine body faces downward when the diesel engine body is filled, and the diesel engine body molten iron filling system adopts an open bottom injection type molten iron filling system, comprising a pouring cup (1), a sprue (2), a horizontal runner (3), and an inner runner (4) connected in sequence; The ingates (4) are connected to an ingates, and the ingates are arranged at the edge of the cylinder bore facing downward on the casting mold and are connected to the inner cavity of the casting mold; The cross-sectional area ratio of the three units of the sprue (2), the runner (3) and the ingrate (4) is ∑F 直 :∑F 横 :∑F 内 =1:2:2, combined with the filling time and the liquid level rising speed, the molten iron flow rate of the ingrate (4) is controlled to be ≤100cm / s; The pouring cup (1) is a quantitative pouring cup with a plug-pulling mechanism.

2. The molten iron filling system for a medium-speed marine diesel engine according to claim 1, Features: The cross-sectional area calculation formula of the sprue (2) is: Where, G is the weight of the cast iron liquid. μ—flow rate coefficient, take 0.46 Pouring time t: where s 1 is the coefficient, taken as 1.9, and δ is the wall thickness of the main part of the casting; Review of metal liquid level rising speed: V 上升 =C / t, C is the casting height, t is the pouring time; To meet the requirements of molten iron rising speed, V 上升 10~20mm / s; Average static head Where C is the height of the casting, H 0 It is the static pressure head of the molten metal. The cross-sectional areas of the runner (3) and the inner runner (4) are calculated based on the proportional relationship of the cross-sectional areas of the three units.

3. The molten iron filling system for a medium-speed marine diesel engine according to claim 1, Features: The inlet of the inner runner (4) overlaps the middle lower position of the horizontal runner (3) in the height direction.

4. The molten iron filling system for a medium-speed marine diesel engine according to claim 1, Features: The sprue (2) is a variable diameter sprue.

5. The molten iron filling system for medium-speed marine diesel engine body according to claim 1, Features: The pouring cup (1) comprises a pouring cup body (1-1), a liquid outlet (1-2) is provided at the bottom of the pouring cup body (1-1), a plug (1-3) for closing and opening the liquid outlet (1-2) is provided inside the pouring cup body (1-1), and the lower end of the plug (1-3) is a spherical structure.

6. The molten iron filling system for medium-speed marine diesel engine body according to claim 1, Features: The sprue (2), runner (3) and inner runner (4) are all made of ceramic tubes of corresponding specifications.

7. The molten iron filling system for medium-speed marine diesel engine body according to claim 1, Features: The diesel engine body is an MPV type diesel engine body.

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