A casting method

Abstract

The present invention relates to the field of casting technology, and in particular to a casting method for a cylinder casting, including calculating and designing a special inner chiller for the thick and large parts of the casting, and manufacturing the special inner chiller, wherein the special inner chiller is provided with an air vent and the air vent can be connected to a compressed air pipeline; during the core making process, a chiller auxiliary core is prepared to cooperate with the use of the special inner chiller, wherein the chiller auxiliary core is provided with an auxiliary channel and the auxiliary channel is connected to the air vent; when assembling the core, the special inner chiller is installed on the main sand core of the cylinder casting, and then the chiller auxiliary core is arranged on the special inner chiller; before pouring, the compressed air pipeline and the air vent are connected and compressed air is introduced. The present invention effectively solves the casting defects of looseness or shrinkage cavity of the casting, improves the quality of the casting, and avoids the problem of leakage of the casting.

Description

Technical Field

[0001] The invention relates to the technical field of casting, in particular to a casting method of a cylinder casting. Background Art

[0002] Compression cylinder castings are mainly used in natural gas booster compressor devices. They are used to withstand large impact loads of natural gas, oil, and water. The most important structure is that the hollow inner wall body formed after the compression cylinder is processed has no quality problems. Casting defects such as looseness or shrinkage directly affect the service life and energy efficiency of the natural gas booster compressor. At present, most domestic and international production of compression cylinder castings are produced by gray iron or low-grade ductile iron casting. The compression cylinder is cast with high-grade ductile iron. The middle part of the cylinder is thick and large, which is prone to looseness and shrinkage. Conventional casting methods cannot meet customer requirements. This series of compression cylinders have looseness or shrinkage defects during the casting process, resulting in casting leakage, and the resulting scrap rate is as high as 60% or more. Summary of the invention

[0003] The present invention overcomes the problem that the method of the prior art that only uses a high and large riser and a large-scale forming chiller cannot completely solve the casting defects of looseness or shrinkage, and provides a casting method that can effectively prevent the problems of looseness and shrinkage in thick and large parts of the cylinder casting body, achieves no casting defects in the thick and large parts of the body, solves the casting scrapping caused by casting leakage quality problems, and improves production efficiency.

[0004] The present invention discloses a casting method, which comprises the following steps: calculating the thick and large parts of cylinder castings, designing and manufacturing a special inner chiller, wherein the special inner chiller is provided with an air vent which can be connected to a compressed air pipeline;

[0005] During the core making process, a chiller auxiliary core is prepared for use with the special inner chiller, an auxiliary channel is provided on the chiller auxiliary core and the auxiliary channel is connected with the vent hole; when assembling the core, the special inner chiller is installed on the main sand core of the casting, and then the chiller auxiliary core is arranged on the special inner chiller; before pouring, the compressed air pipeline and the vent hole are connected and compressed air is introduced.

[0006] In one of the embodiments, the dedicated inner chiller includes a chiller body; a fixed end is provided at one end of the chiller body, and a positioning end is provided at the other end; and anti-rotation reinforcement bars are provided on both sides of the chiller body.

[0007] In one of the embodiments, the chiller body is designed as a cylinder, a thread is arranged on the outer wall of the chiller body, and the size of the chiller body is 50mm-250mm in diameter and 100mm-300mm in height.

[0008] In one embodiment, the cold iron auxiliary core is a square or round pressing core head.

[0009] In one of the embodiments, the vent hole is processed in the axial middle part of the special inner chiller, and a threaded pipe mouth is also processed at one end of the vent hole.

[0010] In one of the embodiments, the compressed air pipeline is inserted into the auxiliary channel and connected to the threaded pipe opening.

[0011] In one embodiment, the main body sand core includes a first main body sand core and a second main body sand core, and the dedicated inner chiller is provided on the first main body sand core or the second main body sand core.

[0012] In one of the embodiments, the wind pressure during ventilation is maintained at 5MPa-6MPa.

[0013] In one embodiment, the ventilation process is kept after the pouring is completed and the ventilation time is controlled to be stopped 2 hours after the pouring is completed.

[0014] The casting method provided by the present invention is applied to the castings of a series of compression cylinders of a certain company, and successfully solves the quality problem of looseness or shrinkage of the hollow inner wall body formed after the compression cylinder is processed. The batch castings of compression cylinders produced by this method have no looseness or shrinkage quality problems found in the casting UT inspection, and no leakage quality problems are found during processing and use. The method of the present invention has been successfully applied to other castings of the same type and products of different materials. The present invention effectively solves the casting defects of looseness or shrinkage, improves the quality of castings, and effectively solves the problem of leakage of castings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of a special inner chiller used in an embodiment of the present invention;

[0016] Figure 2 Schematic diagram of the use of the dedicated inner cooling iron in the embodiment of the present invention in the sand core;

[0017] Figure 3 is a schematic diagram of placing a casting in a casting mold in an embodiment of the present invention;

[0018] Figure 4 It is a schematic diagram of a box assembly in an embodiment of the present invention.

[0019] 100-dedicated inner chiller; 110-chiller body; 120-fixed end; 130-positioning end; 140-anti-rotation tie rod, 150-vent; 200-main body sand core; 210-first main body sand core; 300-chiller auxiliary core; 400-compressed air pipeline DETAILED DESCRIPTION

[0020] In order to more clearly illustrate the technical solution of the present invention, the present invention is further described in detail below in conjunction with specific embodiments. Please note that the embodiments described below are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0021] A casting method is provided in an embodiment of the present invention, which is mainly designed for a casting process method of a compression cylinder casting, and specifically comprises the following steps:

[0022] The first step is to analyze the 2D drawings, calculate the size of the key thick parts of the compression cylinder products, perform bare simulation defect analysis through 3D digital model, design a special inner chiller 100 for the thick structure in the middle of the compression cylinder casting, perform solidification and filling simulation again until the defects are eliminated, and modify the size of the special inner chiller according to the simulation results. Figure 1 , specifically explain the special inner chiller 100, the special inner chiller 100 is designed as a cylinder, and a thread is set on the outer wall of the special inner chiller 100. The thread design increases the special inner chiller to quickly merge with the liquid iron during the pouring process, preventing the formation of a liquid film gap between the main body and the body, resulting in leakage risks. The special inner chiller 100 includes a chiller body 110, a cylindrical structure, and the size of the chiller body 110 is controlled to be 50mm-250mm in diameter and 100mm-300mm in height. If the design of the chiller body is too large, the final shrinkage compensation effect cannot be achieved. The specific size is designed and corrected according to the simulation method in the above steps.

[0023] Furthermore, the special inner chiller 100 also includes a fixed end 120 and a positioning end 130, so as to be used for positioning and fixing the special inner chiller in the sand core. Specifically, the fixed end 120 and the positioning end 130 are core heads, wherein the fixed end 120 is a core pressing head with a length of 30mm-50mm, and the positioning end 130 is a lower core positioning core head with a length of 100mm-150mm. This design facilitates the lower core positioning of the special inner chiller and ensures that the special inner chiller is prevented from tilting and shifting after the core is lowered, thereby reducing the chilling effect of the chiller. At the same time, the special inner chiller is accurately fixed, which facilitates the effective fusion of the special inner chiller. Among them, in this embodiment, the fixed end 120 and the positioning end 130 are set at the middle part of the core head along the axial ends of the inner chiller body 110, the length of the fixed end 120 is 30mm, and the length of the positioning end 130 is 100mm.

[0024] Furthermore, in order to achieve better fixation and fusion effects, anti-rotation tie bars 140 are designed on the special inner chiller 100. Specifically, the anti-rotation tie bars 140 are arranged on both sides of the outer wall of the chiller body 110 and are symmetrically arranged. The anti-rotation tie bars 140 can prevent the special inner chiller 100 from rotating in the casting mold and facilitate the fixation and fusion of the casting body under high-temperature pouring, which can further solve the problem of casting leakage.

[0025] In order to achieve the technical effect of the present invention, the special inner chiller 100 provided by the present invention is also provided with a vent hole 150. The vent hole 150 in this embodiment is designed as a vent hole 150 with a diameter of 10 mm that penetrates the fixed end 120, the chiller body 110 and the positioning end 130. The vent hole 150 can be a through hole with a diameter of 10 mm-12 mm processed in the middle of the special inner chiller for the later introduction of compressed air. Therefore, a threaded pipe mouth is processed at one end of the vent hole 150, and the threaded pipe mouth is used to connect the compressed air pipeline. The specific function of the vent hole is that the vent hole forms a hollow channel. During the pouring process, the high-pressure wind, that is, the flow of compressed air, in the hollow channel of the special inner chiller accelerates the rapid cooling of the special inner chiller. The chilling effect is 3 to 4 times greater than that of conventional chillers, shortening the solidification time of the casting from liquid to solid, resulting in rapid molding of the casting shell, and the shrinkage is successfully completed according to the shrinkage compensation channel. At the same time, it also has the effect of discharging the gas inside the sand core.

[0026] The second step is to make the special inner chiller designed in the first step, and prepare the chiller auxiliary core 300 used in conjunction with the special inner chiller. Specifically, the chiller auxiliary core 300 is a core pressing head, which can be a square or round core pressing head. The chiller auxiliary core 300 is used to fix the special inner chiller 100. At the same time, an auxiliary channel is opened on the chiller auxiliary core 300, which can be combined with Figure 3 First, the cold iron auxiliary core 300 is arranged on the dedicated inner cold iron 100, so as to fix the dedicated inner cold iron and prevent it from rotating and moving. The auxiliary channel arranged on the cold iron auxiliary core 300 can be connected with the vent hole 150, and the compressed air pipe 400 can be inserted into the auxiliary channel. Figure 2 As can be seen in the figure, a compressed air pipe 400 is inserted into the auxiliary channel provided on the cold iron auxiliary core 300, thereby realizing the connection between the external compressed air pipe 400 and the vent hole 150. In this embodiment, a circular core pressing head is provided as the cold iron auxiliary core 300.

[0027] Furthermore, during the core assembly process, the above-mentioned special inner chiller is combined with the main body sand core to form a whole. Specifically, the main body sand core 200 in this embodiment includes a first main body sand core 210 and a second main body sand core, that is, the main body sand core is vertically divided into two parts, the first main body sand core and the second main body sand core. The special inner chiller can be set in any part. In this embodiment, the special inner chiller is combined with the first main body sand core 210 to form a whole. Figure 2 , install the special inner chiller 100 on the first main body sand core 210, and then install the chiller auxiliary core 300 to press the special inner chiller 100 to prevent rotation. The auxiliary channel on the chiller auxiliary core 300 after core assembly is connected with the vent hole 150 of the special inner chiller. After core assembly, the first main body sand core with the special inner chiller and the second main body sand core are combined to form an independent casting mold with the special inner chiller and the main body sand core.

[0028] It is further explained that the steps of the core assembly and box assembly process can be repeated. During the core assembly process, the main sand core and the special inner cooling iron are combined repeatedly, and four independent castings are combined to form a complete core package. After the four complete independent core packages are formed, they are placed in the tooling sand box for pouring. Figure 4 It can be seen that multiple main sand cores can be combined and multiple special internal cooling irons can be set accordingly. During the box assembly process, up to 12 main sand cores can be assembled in one tooling sand box to form a complete independent core package for casting.

[0029] In the pouring step, before pouring, Figure 3 , a compressed air pipe 400 is inserted into the auxiliary channel of the cold iron auxiliary core 300. Since the special inner cold iron 100 is provided with a hollow through hole 150, the connecting pipe port thereon is connected to the connecting pipe of the compressed air pipe 400, and the connecting port is hollow and connected with the special inner cold iron 100. Before pouring, the high-pressure air valve is opened, and the high-pressure air in the special inner cold iron 100 is continuously unobstructed. During the pouring process, the high-pressure air flows in the channel of the special inner cold iron 100, which accelerates the rapid cooling of the special inner cold iron. The chilling effect is 3 to 4 times greater than that of conventional cold iron, shortening the solidification time of the casting from liquid to solid, resulting in rapid molding of the casting shell, and the shrinkage is completed smoothly according to the shrinkage channel, and the gas inside the sand core is discharged. During the pouring process, the wind pressure of the compressed air is maintained at 5MPa-6MPa. The ventilation is stopped 2 hours after the pouring is completed. The hollow inner wall of the casting has a large hot section with shrinkage and cooling has been completed, solving the shrinkage cavity and loose defects. The method provided by the present invention can produce cylinder castings without shrinkage holes and shrinkage problems, and the special inner cooling iron is well integrated with the casting body, thereby preventing the casting body from leaking.

[0030] 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 casting method, characterized in that: For cylinder castings, the method comprises the following steps: Calculate and design a special inner chiller for the thick and large parts of the casting, and produce a vent hole on the special inner chiller, and the vent hole can be connected to a compressed air pipeline; During the core making process, a cold iron auxiliary core is prepared to be used in conjunction with the special inner cold iron, and an auxiliary channel is provided on the cold iron auxiliary core and the auxiliary channel is connected to the vent hole; When assembling the core, the special inner chiller is installed on the main sand core of the casting, and then the chiller auxiliary core is arranged on the special inner chiller; Before pouring, the compressed air pipeline and the vent hole are connected and compressed air is introduced; The special inner chiller comprises a chiller body; a fixed end is arranged at one end of the chiller body, and a positioning end is arranged at the other end; anti-rotation lacing bars are arranged on both sides of the chiller body; the chiller auxiliary core is a square or round core pressing head; The vent hole is processed in the axial middle part of the special inner chiller, and one end of the vent hole is also processed with a threaded pipe mouth; The compressed air pipeline is inserted into the auxiliary channel and connected to the threaded pipe opening.

2. A casting method according to claim 1, characterized in that: The cold iron body is designed as a cylinder, and a thread is arranged on the outer wall of the cold iron body. The size of the cold iron body is 50mm-250mm in diameter and 100mm-300mm in height.

3. A casting method according to claim 1, characterized in that: The main body sand core comprises a first main body sand core and a second main body sand core, and the dedicated inner chiller is arranged on the first main body sand core or the second main body sand core.

4. A casting method according to claim 1, characterized in that: The wind pressure during ventilation is maintained at 5MPa-6MPa.

5. A casting method according to claim 1, characterized in that: The ventilation process is maintained after the pouring is completed, and the ventilation stop time is controlled to be 2 hours after the pouring is completed.

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