A method for casting a ductile iron engine body of an in-line high-speed high-power internal combustion engine

Abstract

The present invention discloses a casting method for a ductile iron engine body of an in-line high-speed and high-power internal combustion engine, comprising the following steps: (1) Casting process design: the engine body cylinder top surface and the oil pan joint surface are divided into a bottom mold, a middle mold and an upper mold, the pouring position adopts vertical pouring with the cylinder hole downward, the position of the inner runner on the casting adopts bottom pouring and side pouring, risers are arranged on the main bearing seat surface of the engine body and the top of the pouring position, and conformal cold irons are placed in thick and large places such as the cylinder hole, the main bearing hole, the bolt hole of the side pull part and the oil channel part; (2) Molds are made according to the designed casting process: molds are made according to the above casting process and engine body drawings. The casting method of the ductile iron engine body of an in-line high-speed and high-power internal combustion engine can effectively avoid shrinkage defects of the ductile iron engine body, ensure the stable working performance of the internal combustion engine, simple operation, low cost, and suitable for popularization and use.

Description

Technical Field

[0001] The invention relates to the technical field of internal combustion engines, in particular to a method for casting a ductile iron engine body of an in-line high-speed and high-power internal combustion engine. Background Art

[0002] The engine block is the skeleton of the internal combustion engine and is used to install almost all parts of the internal combustion engine. It is one of the most important parts of the internal combustion engine and bears a variety of loads. It must have good strength and rigidity and no casting defects such as shrinkage cavities, shrinkage porosity, air holes, and cracks are allowed.

[0003] Internal combustion engine bodies have a large difference in wall thickness and complex structure. They are generally made of gray cast iron and ductile iron. Ductile iron is often used for high-speed and high-power internal combustion engine bodies. When ductile iron solidifies, it has a wide crystallization temperature range and exhibits obvious paste-like solidification characteristics, which makes it easy to produce shrinkage defects. Severe defects will cause the body to be scrapped. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the existing defects and provide a casting method for the ductile iron body of an in-line high-speed and high-power internal combustion engine, which can effectively avoid shrinkage defects in the ductile iron body, ensure the stable working performance of the internal combustion engine, and effectively solve the problems in the background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a casting method for a ductile iron body of an in-line high-speed high-power internal combustion engine, comprising the following steps:

[0006] (1) Casting process design

[0007] The top surface of the cylinder and the joint surface of the oil pan are divided into bottom type, middle type and upper type. The pouring position adopts vertical pouring with the cylinder hole downward, and the position of the entrant on the casting adopts bottom pouring and side pouring. Riser is set on the main bearing seat surface of the body and the top of the pouring position, and the conformal chill is placed in the thick and large places such as the cylinder hole, main bearing hole, bolt hole of the side pull part and the oil channel part.

[0008] (2) Make the mold according to the designed casting process

[0009] According to the above casting process and the machine body drawings, the molds are made. The molds made mainly include: bottom mold, upper mold, front core box, rear core box, 1# cylinder core box, 2#~5# cylinder core boxes, 6# cylinder core box, four side wall core boxes, and strong magnets are installed at the corresponding parts of the mold where the cold iron is placed;

[0010] (3) Modeling and core making

[0011] Insert the upper and lower sand boxes into the bottom mold and upper mold according to the corresponding pin hole positions, and place the sprue and oil pan riser sleeve according to the casting process requirements, then fill in the prepared resin sand, tamp and flatten it. After the resin sand hardens, separate the upper and lower sand boxes from the bottom mold and upper mold to form the bottom mold and upper mold. Fill the prepared resin sand into the core box and tamp it. During the operation, place the accompanying chill, air outlet rope, core bone, and hook, and continue to fill in the prepared resin sand and tamp and flatten it. After the resin sand hardens, take the sand core out of the core box. After the upper and lower molds and sand cores have hardened for 24 hours, apply refractory coating;

[0012] (4) Core assembly

[0013] According to the position of the cylinder core head on the bottom mold, put the 1#, 2#, 3#, 4#, 5#, and 6# cylinder sand cores in turn, and place the 7# and 8# side wall cores of the bottom layer according to the positioning groove position on the bottom mold. Place the 9# and 10# upper side wall cores on the bottom side wall cores. With the side wall core head as a reference, place the front end core and the rear end core on the outside of the 1# and 6# cylinder cores in turn, and put the middle sand box on the bottom mold;

[0014] (5) Box closing

[0015] Fill the prepared resin sand between the middle sand box and the completed core assembly, tamp and flatten it, and close the upper mold. Place a pouring cup on the top surface of the upper mold, surround the vent hole on the top surface of the upper mold with resin sand or sealing mud strips to form an air outlet ring higher than the mold surface, and place the iron weight;

[0016] (6) Melting and pouring

[0017] The molten metal is melted in an induction furnace and spheroidized by the injection method. The temperature of the molten metal out of the furnace is 1450-1490℃, the pouring temperature is 1330-1370℃, and the flow inoculation is carried out during pouring;

[0018] (7) Blank cleaning

[0019] After pouring, the machine body is sanded off, the pouring head is removed, artificial aging is performed, shot blasting is performed, and cleaning and polishing are performed;

[0020] (8) Inspection

[0021] Test the mechanical properties of test pieces, metallographic structure, body hardness and appearance;

[0022] (9)Painting.

[0023] As a preferred technical solution of the present invention, when the cylinder hole is cast vertically downward in step (1), a core head with positioning and supporting functions is designed at the cylinder hole of the cylinder sand core.

[0024] As a preferred technical solution of the present invention, in step (2), the front end core box, the rear end core box and the side wall core box main frame are surrounded by detachable movable blocks.

[0025] As a preferred technical solution of the present invention, the specific materials used to make the mold in step (2) are red pine, resin and metal.

[0026] As a preferred technical solution of the present invention, in step (4), the positioning pins at both ends of the ruler rod are inserted into the positioning pin holes at both ends of the medium sand box, and the core head positions at the oil pans of the 1#, 2#, 3#, 4#, 5#, and 6# cylinder cores are adjusted according to the engraved lines on the ruler rod, and the ruler rod is removed after the adjustment is completed.

[0027] As a preferred technical solution of the present invention, in step (5), the prepared resin sand is filled between the middle sand box and the completed core assembly, compacted and leveled, and the upper mold is closed.

[0028] Compared with the prior art, the invention has the following beneficial effects: the casting method of the ductile iron engine body of the in-line high-speed high-power internal combustion engine is based on the solidification characteristics of ductile iron. In order to ensure the density of the key parts of the engine body and facilitate the shrinkage compensation of molten iron, the parting position is divided into three types: lower, middle and upper types at the top surface of the engine cylinder and the joint surface of the oil pan, the pouring position adopts the downward vertical pouring of the cylinder hole, the position of the inner runner on the casting adopts the bottom pouring side pouring, risers are arranged on the main bearing seat surface of the engine body and the top of the pouring position, resin sand is used to make the mold and core, and after the core is assembled, a middle box is put on the bottom mold, and the prepared resin sand is filled between the middle box and the core assembly and compacted, thereby ensuring the rigidity of the casting mold and increasing the self-shrinkage compensation ability during the solidification process, so that the quality of the produced engine body is stable and the qualified rate is high, which is suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the casting assembly of the present invention;

[0030] Figure 2 It is a schematic diagram of the cylinder core and bottom type;

[0031] Figure 3 It is a schematic diagram of the lower core of the bottom side wall core;

[0032] Figure 4 It is a schematic diagram of the upper sidewall core and the lower core;

[0033] Figure 5 This is a schematic diagram of the end core and the lower core;

[0034] Figure 6 This is a schematic diagram of the ruler rod detecting the cylinder core position;

[0035] Figure 7 This is a schematic diagram of filling the medium sand box with sand;

[0036] Figure 8 This is a diagram after closing the box.

[0037] In the figure: 1 engine body, 2 main bearing seat bolt saddle cold iron, 3 oil pan riser sleeve, 4 air outlet, 5 air outlet ring, 6 side pull bolt saddle cold iron, 7 main bearing seat riser, 8 main oil channel cold iron, 9 cylinder hole lower side cold iron, 10 cylinder hole bolt saddle cold iron, 11 inner gate, 12 horizontal runner, 13 lower sand box, 14 bottom mold, 15 1# cylinder core, 16 2# cylinder core, 17 3# cylinder core, 18 4# cylinder core, 19 5# cylinder core, 20 6# cylinder core, 21 positioning groove, 22 7# bottom side wall core, 23 8# bottom side wall core, 24 9# upper side wall core, 25 10# upper side wall core, 26 front end core, 27 rear end core, 28 cross runner overlap, 29 straight hole ceramic filter, 30 middle sand box, 31 positioning pin, 32 ruler rod, 33 middle type, 34 straight runner, 35 upper sand box, 36 upper type, 37 pouring cup, 38 pressure iron. 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] See also Figure 1-8 The present invention provides a technical solution: a casting method for a ductile iron body of an in-line high-speed high-power internal combustion engine, comprising the following steps:

[0040] (1) Casting process design

[0041] The top surface of the cylinder of the engine body 1 and the joint surface of the oil pan are divided into a bottom mold 14, a middle mold 33 and an upper mold 36. The pouring position adopts vertical pouring with the cylinder hole downward, and the position of the inner runner on the casting adopts bottom pouring and side pouring. A main bearing seat riser 7 is set on the main bearing seat surface of the engine body, and an oil pan riser sleeve 3 is set on the top of the pouring position. The main bearing seat bolt support chill 2, the side pull bolt support chill 6, the main oil channel chill 8, the cylinder hole lower side chill 9 and the cylinder hole bolt support chill 10 are placed in the thick and large parts such as the cylinder hole, the main bearing hole, the bolt hole of the side pull part and the oil channel part, which is conducive to ensuring the quality of the thick and large parts such as the cylinder hole and the main bearing hole bolt. When the cylinder hole is poured vertically downward, a core head with positioning and supporting functions is designed at the cylinder hole of the cylinder sand core;

[0042] (2) Make the mold according to the designed casting process

[0043] According to the above casting process and the machine body drawings, the molds are made. The molds mainly include: bottom mold, upper mold, front end core box, rear end core box, 1# cylinder core box, 2# cylinder core box, 3# cylinder core box, 4# cylinder core box, 5# cylinder core box, 6# cylinder core box, 7# bottom side wall core box, 8# bottom side wall core box, 9# upper side wall core box and 10# upper side wall core box. The front end core box, the rear end core box, the front end core box, the rear end core box and the four side wall core boxes are surrounded by detachable blocks to reduce the draft angle of the mating surface to ensure the core assembly accuracy, and strong magnets are installed at the corresponding positions of the mold where the conformal cold iron is placed.

[0044] (3) Modeling and core making

[0045] On the bottom mold and the upper mold, the upper sand box 35 and the lower sand box 13 are respectively inserted according to the corresponding pin hole positions, and the straight runner 34 and the oil pan riser sleeve 3 are placed according to the casting process requirements, and then the prepared resin sand is filled and tamped and scraped. After the resin sand hardens, the upper sand box 35 and the lower sand box 13 are separated from the bottom mold and the upper mold to form a bottom mold 14 and an upper mold 36. The prepared resin sand is placed in the core box and tamped. During the operation, the accompanying chill, air outlet rope, core bone, and hook are placed, and the prepared resin sand is continued to be filled and tamped and scraped. After the resin sand hardens, the sand core is taken out from the core box, and the refractory coating is applied after the casting mold and sand core are hardened for 24 hours.

[0046] (4) Core assembly

[0047] According to the position of the cylinder core head on the bottom mold 14, the 1# cylinder core 15, 2# cylinder core 16, 3# cylinder core 17, 4# cylinder core 18, 5# cylinder core 19, and 6# cylinder core 20 are placed in sequence, and the 7# bottom layer side wall core 22 and 8# bottom layer side wall core 23 are placed with reference to the position of the positioning groove 21 on the bottom mold 14, and the 9# upper layer side wall core 24 and 10# upper layer side wall core 25 are placed on the bottom layer side wall core. With the side wall core head as a reference, the front end core 26 and the rear end core 27 are placed in sequence outside the 1# cylinder core box 15 and the 6# cylinder core box 20. Put the middle sand box 30 on the bottom mold, insert the positioning pins 31 at both ends of the ruler rod 32 into the positioning pin holes at both ends of the middle sand box 30, and adjust the core head positions of the 1# cylinder core 15, 2# cylinder core 16, 3# cylinder core 17, 4# cylinder core 18, 5# cylinder core 19, and 6# cylinder core 20 at the oil pan according to the engraved lines on the ruler rod 32 respectively. After the adjustment is completed, remove the ruler rod 32 to ensure the position accuracy of the cylinder core.

[0048] (5) Box closing

[0049] Fill the prepared resin sand between the middle sand box 30 and the completed core assembly, tamp and flatten to form a middle mold 33, close the upper mold 36, place a pouring cup 37 on the top surface of the upper mold 36, surround the vent hole 4 on the top surface of the upper mold 36 with resin sand or sealing mud strips to form an air outlet ring 5 higher than the mold surface, and place the iron weight 38;

[0050] (6) Melting and pouring

[0051] The molten metal is melted in an induction furnace and spheroidized by the injection method. The temperature of the molten metal out of the furnace is 1450-1490℃, the pouring temperature is 1330-1370℃, and the flow inoculation is carried out during pouring;

[0052] (7) Blank cleaning

[0053] After the casting, the machine body is placed for 72 hours before sand removal, removal of pouring heads, artificial aging, shot blasting and grinding.

[0054] (8) Inspection

[0055] Test the mechanical properties of test pieces, metallographic structure, body hardness and appearance;

[0056] (1)Painting.

[0057] Apply anti-rust primer as required.

[0058] The upper mold 36 is provided with an air outlet 4, and the bottom mold 14 also includes a straight hole ceramic filter 29, which is located in the cross runner overlap portion 28. The molten metal sequentially passes through the pouring cup 37, the sprue 34, the cross runner overlap portion 28, the straight hole ceramic filter 29, the cross runner 12, the inner gate 11, the machine body 1, the main bearing seat riser 7, the oil pan riser sleeve 3, and the air outlet 4. The pouring system is open, the impact of the molten iron on the machine body cavity is small, the filling is stable, and the gas in the cavity is easy to be discharged in sequence. The use of cold iron and risers can achieve overall sequential solidification and local simultaneous solidification.

[0059] The invention has the advantages of simple operation, wide application range, low investment, universal sand boxes when the machine body models are different but the external dimensions are not much different, convenient production organization, stable quality and high qualified rate of the machine body produced by the invention, no shrinkage defects, and is suitable for large-scale promotion and application.

[0060] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for casting a ductile iron body of an in-line high-speed high-power internal combustion engine, characterized in that: The following steps are involved: (1) Casting process design The top surface of the cylinder and the joint surface of the oil pan are divided into bottom type, middle type and upper type. The pouring position adopts vertical pouring with the cylinder hole downward, and the position of the entrant on the casting adopts bottom pouring and side pouring. Riser is set on the main bearing seat surface of the body and the top of the pouring position, and the conformal chill is placed in the thick and large places such as the cylinder hole, main bearing hole, bolt hole of the side pull part and the oil channel part. (2) Make the mold according to the designed casting process According to the above casting process and the machine body drawings, the molds are made. The molds made mainly include: bottom mold, The upper mold, the front core box, the rear core box, the 1# cylinder core box, the 2# to 5# cylinder core boxes, the 6# cylinder core box, the four side wall core boxes, install strong magnets at the corresponding positions where the conformal chill is placed on the mold; (3) Modeling and core making On the bottom mold and the upper mold, insert the upper and lower sand boxes according to the corresponding pin hole positions, place the sprue and riser sleeve according to the casting process requirements, fill in the prepared resin sand, tamp and scrape it flat. After the resin sand hardens, separate the upper and lower sand boxes from the bottom mold and the upper mold to form a bottom mold and an upper mold. Fill the prepared resin sand in the core box and tamp it. During the operation, place the accompanying chill, air outlet rope, core bone, and hook, and continue to fill in the prepared resin sand and tamp and scrape it flat. After the resin sand hardens, take the sand core out of the core box, and apply refractory paint after the upper and lower molds and sand cores harden for 24 hours; (4) Core assembly According to the position of the cylinder core head on the bottom mold, put the 1#, 2#, 3#, 4#, 5#, and 6# cylinder sand cores in turn, and place the 7# and 8# side wall cores of the bottom layer according to the positioning groove position on the bottom mold. Place the 9# and 10# upper side wall cores on the bottom side wall cores. With the side wall core head as a reference, place the front end core and the rear end core on the outside of the 1# and 6# cylinder cores in turn, and put the middle sand box on the bottom mold; (5) Packing Fill the prepared resin sand between the middle sand box and the completed core assembly, and close the upper mold; (6) Melting and pouring The molten metal is melted in an induction furnace and spheroidized by the injection method. The temperature of the molten metal out of the furnace is 1450-1490℃, the pouring temperature is 1330-1370℃, and the flow inoculation is carried out during pouring; (7) Cleaning of blanks After pouring, the machine body is sanded off, the pouring head is removed, artificial aging is performed, shot blasting is performed, and cleaning and polishing are performed; (8) Inspection Test the mechanical properties of test pieces, metallographic structure, body hardness and appearance; (9) Painting.

2. The casting method of a ductile iron body of an in-line high-speed high-power internal combustion engine according to claim 1, characterized in that: In step 1, when the cylinder hole is poured vertically downward, a core head with positioning and supporting functions is designed at the cylinder hole of the cylinder sand core.

3. The casting method of a ductile iron body of an in-line high-speed high-power internal combustion engine according to claim 1, characterized in that: In step 2, the front end core box, the rear end core box, and the side wall core box main frame are surrounded by detachable movable blocks.

4. The casting method of a ductile iron body of an in-line high-speed high-power internal combustion engine according to claim 1, characterized in that: The specific materials for making the mold in step 2 are red pine, resin and metal.

5. The casting method of a ductile iron body of an in-line high-speed high-power internal combustion engine according to claim 1, characterized in that: In step 4, insert the locating pins at both ends of the ruler rod into the locating pin holes at both ends of the medium sand box, and adjust the core head position at the oil pan of 1#, 2#, 3#, 4#, 5#, and 6# cylinder cores according to the engraved lines on the ruler rod. After the adjustment is completed, remove the ruler rod.

6. The method for casting a ductile iron body of an in-line high-speed and high-power internal combustion engine according to claim 1, characterized in that: Step 5: Fill the prepared resin sand between the medium sand box and the completed core assembly, tamp and smooth it, and close the upper mold.

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