A method for casting a crankshaft of a marine diesel engine

Abstract

The present invention relates to a method for casting a marine diesel engine crankshaft, comprising the following casting steps: starting an exhaust hole plugging machine assembly to plug the exhaust hole, filling molding sand into an upper mold and a lower mold, arranging the molding sand using a crankshaft pattern, taking out the crankshaft pattern for mold closing and then pouring molten iron, closing the exhaust hole and fitting a heat dissipation assembly to a thick-walled part of the crankshaft for heat dissipation, and balancing the cooling speed of the thick wall and thin wall of the crankshaft. The present invention arranges a mold with an exhaust hole between the molding sand and the mold box, and forms an exhaust cavity between the mold and the mold box, which can guide the gas generated from the upper and lower surfaces of the crankshaft casting upward and downward, ensuring that the cooling speed of the upper and lower surfaces of the crankshaft casting is consistent. In addition, when the exhaust hole on the mold is opened, the heat dissipation assembly can be driven to fit the mold, accelerating the cooling speed of the thick-walled part of the crankshaft, making it consistent with the cooling speed of the thin-walled part of the crankshaft, and achieving the effects of consistent quality of various parts of the crankshaft and not easy to break.

Description

Technical Field

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

[0002] The crankshaft is the most important part of the engine. It bears the force from the connecting rod and converts it into torque, which is output through the crankshaft and drives other accessories on the engine. The crankshaft is subjected to the combined effects of the centrifugal force of the rotating mass, the periodically changing gas inertia force and the reciprocating inertia force, which makes the crankshaft subject to bending and torsion loads. Therefore, the crankshaft is required to have sufficient strength and rigidity, the journal surface needs to be wear-resistant, work evenly and have good balance, so it is generally cast with ductile iron.

[0003] When the diesel engine crankshaft is cast with ductile iron, after casting, the different thicknesses of various parts of the crankshaft cause different cooling rates of the crankshaft parts, which easily form shrinkage cavities and shrinkage at the locations where the thickness of the crankshaft changes suddenly, reducing the strength of the crankshaft and concentrating the internal stress of the crankshaft, affecting the service life of the crankshaft. In addition, in the prior art, the exhaust holes are generally arranged in the molding sand in the upper mold box. When exhausting, the gas generated at the top and bottom of the crankshaft casting is discharged unevenly, which also leads to different cooling rates on the upper and lower surfaces, resulting in uneven surface quality and reduced crankshaft strength. Summary of the invention

[0004] The object of the present invention is to provide a method for casting a crankshaft of a marine diesel engine in order to solve the above-mentioned problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A method for casting a crankshaft of a marine diesel engine, comprising the following casting steps:

[0007] S1, suspending and fixing the upper mold and the lower mold with exhaust holes on the surface in the upper mold box and the lower mold box respectively, and starting the exhaust hole plugging machine assembly to plug the exhaust holes;

[0008] S2, filling the upper mold and the lower mold with molding sand, arranging the molding sand using the crankshaft pattern, taking out the crankshaft pattern and closing the mold;

[0009] S3, pouring the molten iron after inoculation treatment into the cavity formed by the upper mold box and the lower mold box, starting the exhaust hole plugging machine component to open the exhaust hole, and fitting the heat dissipation component to the thick wall part of the crankshaft for heat dissipation, balancing the cooling speed of the thick wall and thin wall of the crankshaft;

[0010] S4. After casting, the mold is opened to take out the crankshaft casting, and after cooling, it is cleaned, polished, tempered and tested in sequence to obtain the finished crankshaft.

[0011] As a further optimization scheme of the present invention, an exhaust cavity is arranged between the top of the upper mold and the upper mold box, and between the bottom of the lower mold and the lower mold box. Exhaust pipes are connected to the side walls of the upper mold box and the lower mold box corresponding to both sides of the exhaust cavity for discharging the gas discharged from the exhaust hole.

[0012] As a further optimization scheme of the present invention, a pouring tube is fixedly provided on the upper mold, the bottom end of the pouring tube penetrates the molding sand and extends to the lower surface of the molding sand, and the top end of the pouring tube penetrates the upper surface of the upper mold box and forms a pouring port on the upper surface of the upper mold box.

[0013] As a further optimization scheme of the present invention, in step S2, before closing the mold, the heating components in the upper mold, the lower mold and the crankshaft mold are started to preheat the molding sand to a certain temperature before taking out the crankshaft mold; the heating component includes a heating tube and a preheating system connected to the heating tube, and the upper mold, the lower mold and the crankshaft mold are all made of aluminum alloy material.

[0014] As a further optimization scheme of the present invention, the exhaust hole plugging machine assembly is connected to the heat dissipation assembly via a linkage mechanism. When the linkage mechanism drives the exhaust hole plugging machine assembly to open the exhaust port, it simultaneously drives the heat dissipation assembly to fit the thick wall portion of the crankshaft.

[0015] As a further optimization scheme of the present invention, the exhaust hole plugging machine assembly includes an electric push rod, a cross bar, an insertion rod, and a plugging head. The bottom of the cross bar is connected to the electric push rod, and the top is connected to a plurality of insertion rods. The plugging head fixedly connected to the top of each insertion rod is inserted into the exhaust hole.

[0016] As a further optimization scheme of the present invention, the heat dissipation assembly includes a connecting rod, a plurality of heat-conducting rods fixed on the connecting rod, and a heat-conducting plate fixed to one end of the heat-conducting rod. The connecting rod, the heat-conducting rod and the heat-conducting plate are all made of aluminum alloy material, and one end of the heat-conducting rod away from the heat-conducting plate passes through the upper mold box / lower mold box.

[0017] As a further optimization scheme of the present invention, the linkage mechanism is arranged between the connecting rod and the cross rod, and the linkage mechanism includes a long board, a rotating shaft and a support seat. The middle part of the long board is rotatably connected to the support seat at the bottom through the rotating shaft.

[0018] As a further optimization scheme of the present invention, the interior of the heat-conducting rod and the connecting rod are both hollow, and the two ends of the hollow inner cavity are connected to the liquid cooling system through a liquid inlet hose and a liquid outlet hose. The liquid cooling system outputs the circulating coolant to the heat dissipation component, and the heat is dissipated to the thick-walled part of the crankshaft through the heat dissipation component, the mold and the molding sand, thereby accelerating the cooling speed of the thick-walled part of the crankshaft.

[0019] The beneficial effects of the present invention are:

[0020] 1) The present invention arranges a mold between the molding sand and the mold box, forms an exhaust cavity between the mold and the mold box, and opens an exhaust hole on the mold, which can discharge the gas generated by the upper and lower surfaces of the crankshaft casting upward and downward, ensuring that the cooling speed of the upper and lower surfaces of the crankshaft casting is consistent. In addition, when the exhaust hole on the mold is opened, the heat dissipation component can be driven to fit the mold, thereby accelerating the cooling speed of the thick-walled part of the crankshaft to make it consistent with the cooling speed of the thin-walled part of the crankshaft, thereby achieving the effects of consistent quality of various parts of the crankshaft and not easy to break;

[0021] 2) The present invention provides an exhaust hole on the mold, and the exhaust hole is blocked or opened by the exhaust hole blocking assembly, so that the pouring pipe is fixedly connected to the upper mold as a whole. When in use, it only needs to cover the molding sand, and there is no need to open a pouring hole or an exhaust hole separately. Compared with the prior art, when making the sand box, the exhaust hole and the pouring hole need to be set separately. The present invention simplifies the sand box manufacturing steps, is quick and convenient to operate, and greatly improves the production efficiency;

[0022] 3) The present invention utilizes the mold to isolate the molding sand, the vent plugging component, and the heat dissipation component, and arranges a heating component in the mold, so that the advantages of the molding sand can still be utilized during the casting molding process, the amount of molding sand can be reduced, and the mold can also be used to preheat and keep the casting warm, and to dissipate heat during the molding process, and the vent plugging component and the heat dissipation component can be isolated and protected, so that the entire casting device can be repeatedly recycled and mass-produced crankshaft castings;

[0023] 4) The present invention adopts a linkage mechanism to connect the exhaust hole plugging machine component and the heat dissipation component, which can dissipate heat to the thick wall part of the crankshaft while opening the exhaust hole. It has a simple structure and saves energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall cross-sectional structure of the present invention during preheating before pouring.

[0025] Figure 2 The present invention Figure 1 Schematic diagram of the structure of part A.

[0026] Figure 3 It is a schematic diagram of the overall cross-sectional structure of the present invention during pouring.

[0027] Figure 4 It is a schematic diagram of the linkage mechanism structure of the present invention.

[0028] In the figure: 1. upper mold box; 2. lower mold box; 3. upper mold; 4. lower mold; 5. exhaust hole; 6. exhaust hole plugging machine assembly; 61. electric push rod; 62. cross bar; 63. insert rod; 64. plugging head; 7. exhaust chamber; 8. linkage mechanism; 81. long plate; 82. rotating shaft; 83. support seat; 9. heat dissipation assembly; 91. connecting rod; 92. heat conducting rod; 93. heat conducting sheet; 10. heating assembly; 11. casting tube; 12. liquid cooling system; 13. exhaust pipe. DETAILED DESCRIPTION

[0029] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0030] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 a limitation on the present invention; in the description of the present invention, unless otherwise specified, "multiple" and "several" mean two or more.

[0031] Example 1

[0032] like Figure 1-3 As shown, a method for casting a crankshaft for a marine diesel engine comprises the following casting steps:

[0033] S1, suspending and fixing the upper mold 3 and the lower mold 4 with exhaust holes 5 on the surface in the upper mold box 1 and the lower mold box 2 respectively, and starting the exhaust hole plugging machine assembly 6 to plug the exhaust hole 5;

[0034] S2, fill the molding sand into the upper mold 3 and the lower mold 4, arrange the molding sand using the crankshaft pattern, start the upper mold 3, the lower mold 4 and the heating component 10 in the crankshaft pattern, preheat the molding sand to above 500° C., then take out the crankshaft pattern, and close the mold. After closing the mold, the heating component 10 in the mold continues to heat to ensure the high temperature in the mold cavity, which is conducive to the smooth entry of molten iron without solidification;

[0035] S3, pouring the molten iron after inoculation treatment into the cavity formed by the upper mold box 1 and the lower mold box 2, starting the exhaust hole plugging machine component 6 to open the exhaust hole 5, and fitting the heat dissipation component 9 to the thick wall part of the crankshaft to dissipate heat, balancing the cooling speed of the thick wall and thin wall of the crankshaft;

[0036] S4. After casting, the mold is opened to take out the crankshaft casting, and after cooling, it is cleaned, polished, tempered and tested in sequence to obtain the finished crankshaft.

[0037] in,

[0038] An exhaust cavity 7 is provided between the top of the upper mold 3 and the upper mold box 1 and between the bottom of the lower mold 4 and the lower mold box 2. Exhaust pipes 13 are connected to the side walls of the upper mold box 1 and the lower mold box 2 corresponding to both sides of the exhaust cavity 7 to discharge the gas discharged from the exhaust hole 5.

[0039] A pouring pipe 11 is fixedly provided on the upper mold 3 , the bottom end of the pouring pipe 11 penetrates the molding sand and extends to the lower surface of the molding sand, and the top end of the pouring pipe 11 penetrates the upper surface of the upper mold box 1 and forms a pouring port on the upper surface of the upper mold box 1 .

[0040] The heating assembly 10 includes a heating tube and a preheating system connected to the heating tube. The preheating system can be a hot air furnace. The heating tubes are evenly distributed in the upper mold 3, the lower mold 4 and the crankshaft mold and are connected to the external hot air furnace. The hose connected to the heating tube in the crankshaft mold can be connected to the external hot air furnace through the pouring pipe 11. High-temperature gas exceeding 500°C is passed into the heating tube for preheating. The upper mold 3, the lower mold 4 and the crankshaft mold are all made of aluminum alloy.

[0041] It should be noted that the entire crankshaft casting method of the present invention improves the sand box in the prior art, arranges an aluminum alloy mold between the molding sand and the mold box, and opens an exhaust hole 5 on the mold. In the casting molding process, the advantages of the molding sand are still utilized, and the amount of molding sand can be reduced. The mold is used to preheat and insulate the casting and to dissipate heat during the molding process. The exhaust holes 5 on the mold are used to exhaust evenly up and down, and there is no need to process the exhaust holes 5, pouring holes, etc. separately. The entire casting device has a simple structure, can mass-produce crankshaft castings, and the quality of each part of the cast crankshaft is consistent;

[0042] The present invention utilizes the exhaust cavity 7 formed between the upper mold 3, the lower mold 4 and the mold box, and the exhaust holes 5 are arranged on the upper mold 3 and the lower mold 4. The molding sand can exhaust the gas generated at the top and bottom of the crankshaft casting to the exhaust hole 5, and then to the exhaust cavity 7, and finally to the exhaust pipe 13. This design can make the top and bottom of the crankshaft casting evenly exhausted, does not affect the cooling speed of the top and bottom of the casting, and makes its surface quality consistent;

[0043] By fixing the pouring tube 11 and the upper mold 3 together, it only needs to cover the molding sand during use, and there is no need to open a separate pouring hole. The mold is provided with a vent hole 5 and connected to the exhaust cavity 7, and there is no need to open a separate vent hole 5. Compared with the prior art in which the vent hole 5 and the pouring hole need to be set separately when making the sand box, the present invention simplifies the sand box manufacturing steps, is quick and convenient to operate, and greatly improves production efficiency.

[0044] like Figure 3-4 As shown, the exhaust hole plugging machine assembly 6 and the heat dissipation assembly 9 are connected via a linkage mechanism 8. When the linkage mechanism 8 drives the exhaust hole plugging machine assembly 6 to open the exhaust port, it simultaneously drives the heat dissipation assembly 9 to fit the thick wall portion of the crankshaft.

[0045] The exhaust hole plugging machine assembly 6 includes an electric push rod 61, a cross bar 62, an insertion rod 63, and a plugging head 64. The bottom of the cross bar 62 is connected to the electric push rod 61, and the top is connected to a plurality of insertion rods 63. The plugging head 64 fixedly connected to the top of each insertion rod 63 is inserted into the exhaust hole 5.

[0046] The heat dissipation assembly 9 includes a connecting rod 91, a plurality of heat-conducting rods 92 fixed on the connecting rod 91, and a heat-conducting plate 93 fixed to one end of the heat-conducting rod 92. The connecting rod 91, the heat-conducting rod 92, and the heat-conducting plate 93 are all made of aluminum alloy material. The end of the heat-conducting rod 92 away from the heat-conducting plate 93 passes through the upper mold box 1 / lower mold box 2.

[0047] The linkage mechanism 8 is disposed between the connecting rod 91 and the cross rod 62 . The linkage mechanism 8 includes a long plate 81 , a rotating shaft 82 and a supporting seat 83 . The middle portion of the long plate 81 is rotatably connected to the supporting seat 83 at the bottom via the rotating shaft 82 .

[0048] It should be noted that before the molding sand covers the mold, the electric push rod 61 pushes the plugging head 64 at the end of the plugging rod 63 through the cross bar 62 to insert into the exhaust hole 5, blocking the exhaust hole 5 to prevent the molding sand from falling into the exhaust hole 5 and the exhaust cavity 7. After the molding sand solidifies and before pouring, the electric push rod 61 drives the plugging head 64 to separate from the exhaust hole 5 through the cross bar 62 and the plugging rod 63, so as to facilitate the discharge of gas from the molding sand during the pouring process. At the same time, the downwardly moved cross bar 62 will drive one end of the long plate 81 to move downward, and the middle part of the long plate 81 will drive the rotating shaft 82 to rotate. , so that the other end of the long plate 81 is tilted, and the tilted end of the long plate 81 lifts the connecting rod 91, and the connecting rod 91 drives the heat-conducting rod 92 and the heat-conducting sheet 93 to move up and fit the mold surface, and the molding sand conducts the heat of the thick-walled part of the crankshaft casting to the aluminum alloy mold, and then conducts it to the outside of the sand box through the aluminum alloy heat-conducting sheet 93 and the heat-conducting rod 92 in turn, and contacts with the air, thereby realizing rapid heat dissipation and cooling of the thick-walled part of the crankshaft casting, thereby balancing the cooling speed of the thick wall and the thin wall, avoiding the formation of shrinkage cavities and shrinkage at the part where the thickness of the crankshaft suddenly changes, and reducing the strength of the crankshaft;

[0049] In addition, when the molding sand is subsequently removed, the electric push rod 61 can be started to push the insertion rod 63 and the plugging head 64 at its end through the cross bar 62 to insert out of the exhaust hole 5, so that the molding sand can be easily ejected to the outside of the mold;

[0050] like Figure 1-3 As shown, the interior of the heat-conducting rod 92 and the connecting rod 91 are both hollow, and the two ends of the hollow inner cavity are connected to the liquid cooling system 12 through a liquid inlet hose and a liquid outlet hose. The liquid cooling system 12 outputs the circulating coolant to the heat dissipation component 9, and the heat is dissipated to the thick-walled part of the crankshaft through the heat dissipation component 9, the mold and the molding sand, so that the cooling speed of the thick-walled part of the crankshaft is accelerated.

[0051] It should be noted that, in order to ensure that the cooling speed of the thick wall and the thin wall is consistent, a temperature sensor can be set in the corresponding mold to monitor the temperature, and the cooling temperature of the coolant is controlled by the liquid cooling system 12 according to the monitored temperature, so that the cooling speed of the thick wall and the thin wall is consistent;

[0052] The entire heat dissipation component 9 is arranged in the exhaust cavity 7 and does not contact the molding sand. When the sand box is reused, only the molding sand needs to be operated, and the molding sand will not affect the heat dissipation component 9. The heat dissipation component 9 can be reused many times like the mold. The entire casting device is easy to operate and has a long service life.

[0053] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for casting a crankshaft for a marine diesel engine, characterized in that: The casting steps include: S1, suspending and fixing the upper mold and the lower mold with exhaust holes on the surface in the upper mold box and the lower mold box respectively, and starting the exhaust hole plugging machine assembly to plug the exhaust holes; The exhaust hole plugging machine assembly is connected to the heat dissipation assembly through a linkage mechanism. When the linkage mechanism drives the exhaust hole plugging machine assembly to open the exhaust port, the heat dissipation assembly is simultaneously driven to fit the thick-walled part of the crankshaft; the exhaust hole plugging machine assembly comprises an electric push rod, a cross bar, an insertion rod, and a plugging head. The bottom of the cross bar is connected to the electric push rod, and the top is connected to a plurality of insertion rods. The plugging head fixedly connected to the top of each insertion rod is inserted into the exhaust hole; the heat dissipation assembly comprises a connecting rod, a plurality of heat-conducting rods fixed on the connecting rod, and a heat-conducting sheet fixed to one end of the heat-conducting rod. The connecting rod, the heat-conducting rod, and the heat-conducting sheet are all made of aluminum alloy material, and the end of the heat-conducting rod away from the heat-conducting sheet passes through the upper mold box / lower mold box; the linkage mechanism is arranged between the connecting rod and the cross bar; S2, filling the upper mold and the lower mold with molding sand, arranging the molding sand using the crankshaft pattern, taking out the crankshaft pattern and closing the mold; S3, pouring the molten iron after inoculation treatment into the cavity formed by the upper mold box and the lower mold box, starting the exhaust hole plugging machine component to open the exhaust hole, and fitting the heat dissipation component to the thick wall part of the crankshaft for heat dissipation, balancing the cooling speed of the thick wall and thin wall of the crankshaft; S4. After casting, the mold is opened to take out the crankshaft casting, and after cooling, it is cleaned, polished, tempered and tested in sequence to obtain the finished crankshaft.

2. A marine diesel engine crankshaft casting method according to claim 1, characterized in that: An exhaust cavity is provided between the top of the upper mold and the upper mold box, and between the bottom of the lower mold and the lower mold box. Exhaust pipes are connected to the side walls of the upper mold box and the lower mold box corresponding to both sides of the exhaust cavity to discharge the gas discharged from the exhaust hole.

3. A marine diesel engine crankshaft casting method according to claim 1, characterized in that: A pouring pipe is fixedly provided on the upper mold, the bottom end of the pouring pipe penetrates the molding sand and extends to the lower surface of the molding sand, and the top end of the pouring pipe penetrates the upper surface of the upper mold box and forms a pouring port on the upper surface of the upper mold box.

4. A method for casting a marine diesel engine crankshaft according to claim 1, characterized in that: In step S2, before closing the mold, the heating components in the upper mold, the lower mold and the crankshaft mold are started to preheat the molding sand to a certain temperature before taking out the crankshaft mold; the heating components include a heating tube and a preheating system connected to the heating tube, and the upper mold, the lower mold and the crankshaft mold are all made of aluminum alloy material.

5. A marine diesel engine crankshaft casting method according to claim 1, characterized in that: The linkage mechanism comprises a long board, a rotating shaft and a supporting seat, and the middle part of the long board is rotatably connected to the supporting seat at the bottom through the rotating shaft.

6. A marine diesel engine crankshaft casting method according to claim 1, characterized in that: The interior of the heat-conducting rod and the connecting rod are both hollow, and the two ends of the hollow inner cavity are connected to the liquid cooling system through a liquid inlet hose and a liquid outlet hose. The liquid cooling system outputs circulating coolant to the heat dissipation component, which dissipates heat to the thick-walled parts of the crankshaft through the heat dissipation component, the mold and the molding sand, thereby accelerating the cooling speed of the thick-walled parts of the crankshaft.

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