Casting system and method of CT machine stator for low-pressure casting

Abstract

The invention relates to a casting system and method of a CT machine stator for low-pressure casting. The casting system is characterized by comprising a sprue, a cross gate, an inner ring vertical gate and an outer ring vertical gate, according to the invention, CT machine stator casting molding is carried out in an inverted low-pressure liquid rising casting molding mode; the weight of the casting system is reduced by more than 50%, and the casting yield is improved; meanwhile, the process of removing a dead head in machining is omitted, the machining efficiency is improved by 50% or above, real low-pressure casting and pressure solidification are achieved, the feeding effect is good, and the compactness of a casting structure is improved; the positions of the inner and outer runners are arranged, so that the punching effect of the product is better, and a hot spot is easy to eliminate; the surface of a cavity of the casting mold is coated with a refractory material layer, so that molten aluminum cannot enter a sand mold to generate gas at high temperature during long-time pressurization and pressure maintaining, and the shrinkage porosity phenomenon is avoided.

Description

Technical Field

[0001] The invention relates to the field of CT machine stator casting systems, and in particular to a casting system and method for a CT machine stator used for low-pressure casting. Background Art

[0002] At present, the commonly used casting method for CT machine stators in the world is low-pressure casting with a mold with a riser and not closed. The shrinkage compensation of the casting is achieved through the riser, which is usually called open low-pressure casting. This process has certain defects: a. A casting system with a large-diameter riser is used. The gate is designed on the side of the mold away from the connecting ribs, and several risers are set on the side with the connecting ribs for exhaust and shrinkage compensation. The metal liquid process yield is low and there are many machining processes; b. The setting of the riser makes it only use low pressure for filling the mold, and it is impossible to use the process of pressurized crystallization. It is not a true low-pressure casting, the shrinkage compensation effect is slightly poor, and the density of the casting structure is affected to a certain extent; c. The casting system uses the riser structure in traditional gravity casting as the gate, and the gate is flat. The hot node is not easy to eliminate, and there are shrinkage and holes. Therefore, when using this process to produce CT machine stators, high requirements are placed on both the process and equipment. When the above-mentioned low-pressure filling process is used to produce this product in China, the qualified rate of castings is very low. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a casting system for a CT machine stator used for low-pressure casting, which can solve the problems of high molten metal yield, long processing cycle and low casting structure fatalness in general CT machine stator casting.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: a casting system for a CT machine stator for low-pressure casting, the innovation of which is: comprising a gate, a horizontal runner, an inner ring vertical runner and an outer ring vertical runner; The bottom end of the gate is connected to the output end of the crucible furnace, and the top end of the gate is provided with a plurality of horizontal runners in a divergent shape along the four sides, and each horizontal runner is provided with an inner circle vertical runner and an outer circle vertical runner corresponding to the inner circle position of the CT machine and the outer circle position of the CT machine, respectively.

[0005] The cross sections of the gate, the runner, the inner ring vertical runner and the outer ring vertical runner are all wedge-shaped structures.

[0006] A casting method for a CT machine stator for low-pressure casting, the innovation of which is: the specific casting process is as follows: S1: Use resin sand to shape and make cores according to the shape of the CT machine stator; S2: Brushing refractory coating on the surface of the mold cavity and igniting it; S3: Drying and mold closing of the mold: After the mold enters the drying box, it is heated to 150℃-170℃ and kept at a constant temperature for 2-4 hours; then the core is placed, and a 30mm thick inner ring chill and a 15mm thick outer ring chill are densely placed in the thick part of the inner and outer rings, and finally the box is closed; at the same time, several exhaust cooling pins are added in the area where the variable-section chill is not set; S4: After the box is assembled, it is placed on a cast iron crucible furnace for low-pressure pouring. The pouring temperature is between 700℃ and 750℃, the filling speed is 5-20cm / s, and the filling time is 70-90s. The boost pressure is 1-1.2 kPa, the holding pressure is 1-1.5 kPa, and the holding time is 10-30s. The pressure must be released slowly, and it must not be released quickly. Unpacking and cleaning: The workpiece can be unpacked after it has cooled naturally for 2 hours, and the blank can be taken out.

[0007] The advantages of the present invention are: 1) The inverted low-pressure liquid rising casting method of the present invention is used to cast the stator of the CT machine; the weight of the casting system is reduced by more than 50%, and the casting yield is improved; at the same time, the process of removing the riser in machining is omitted, and the machining efficiency is improved by more than 50%, realizing true low-pressure casting, pressure solidification, good shrinkage compensation effect, and improved density of the casting structure; the position setting of the inner and outer runners makes the product's punching effect better and the hot node is easy to eliminate; the surface of the mold cavity is coated with a refractory material layer to ensure that during long-term pressurization and pressure maintenance, the aluminum liquid will not enter the sand mold to generate high-temperature gas, thereby avoiding shrinkage. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0009] Figure 1 The present invention is a structural diagram of a casting system for a CT machine stator used for low-pressure casting. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0011] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0012] like Figure 1 The casting system of a CT machine stator for low-pressure casting shown in the figure comprises a gate 1, a runner 2, an inner ring vertical runner 3 and an outer ring vertical runner 4.

[0013] The bottom end of the gate 1 is connected to the output end of the crucible furnace, and the top of the gate 1 is provided with a plurality of horizontal runners 2 in a divergent shape along the four sides, and each horizontal runner 2 is provided with an inner circle vertical runner 3 and an outer circle vertical runner 4 corresponding to the inner circle position of the CT machine and the outer circle position of the CT machine, respectively.

[0014] The gate 1, the runner 2, the inner ring vertical runner 3 and the outer ring vertical runner 4 all have wedge-shaped surface structures in cross section.

[0015] A casting method for a CT machine stator for low-pressure casting, the specific casting process is as follows: S1: Use resin sand to shape and make cores according to the shape of the CT machine stator; S2: Brushing refractory coating on the surface of the mold cavity and igniting it; S3: Drying and mold closing of the mold: After the mold enters the drying oven, it is heated to 150℃-170℃ and kept at a constant temperature for 2-4 hours; then the core is placed, and a 30mm thick inner ring chiller and a 15mm thick outer ring chiller are densely placed in the thick part of the inner and outer rings, so that the inner ring is cooled and compensated for shrinkage first to reduce shrinkage holes and shrinkage on the inner ring processing surface, and finally the box is closed; at the same time, a number of exhaust cooling pins are added in the area where the variable-section chiller is not set; S4: After the box is assembled, it is placed on a cast iron crucible furnace for low-pressure pouring. The pouring temperature is between 700℃ and 750℃, the filling speed is 5-20cm / s, and the filling time is 70-90s. The boost pressure is 1-1.2 kPa, the holding pressure is 1-1.5 kPa, and the holding time is 10-30s. The pressure must be released slowly, and it must not be released quickly. Unpacking and cleaning: The workpiece can be unpacked after it has cooled naturally for 2 hours, and the blank can be taken out.

[0016] Those skilled in the art should understand that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, and these changes and improvements shall all fall within the scope of the present invention claimed for protection.

Claims

1. A casting system for a CT machine stator for low-pressure casting, characterized in that: Including gate, runner, inner ring vertical runner and outer ring vertical runner; The bottom end of the gate is connected to the output end of the crucible furnace, and the top end of the gate is provided with a plurality of horizontal runners in a divergent shape along the four sides, and each horizontal runner is provided with an inner circle vertical runner and an outer circle vertical runner corresponding to the inner circle position of the CT machine and the outer circle position of the CT machine, respectively.

2. The casting system for low-pressure casting of a CT machine stator according to claim 1, characterized in that: The cross sections of the gate, the runner, the inner ring vertical runner and the outer ring vertical runner are all wedge-shaped structures.

3. A casting method for a CT machine stator for low-pressure casting, characterized in that: The specific casting process is as follows: S1: Use resin sand to shape and make cores according to the shape of the CT machine stator; S2: Brushing refractory coating on the surface of the mold cavity and igniting it; S3: Drying and mold closing of the mold: After the mold enters the drying box, it is heated to 150℃-170℃ and kept at a constant temperature for 2-4 hours; then the core is placed, and a 30mm thick inner ring chill and a 15mm thick outer ring chill are densely placed in the thick part of the inner and outer rings, and finally the box is closed; at the same time, several exhaust cooling pins are added in the area where the variable-section chill is not set; S4: After the box is assembled, it is placed on a cast iron crucible furnace for low-pressure pouring. The pouring temperature is between 700℃ and 750℃, the filling speed is 5-20cm / s, and the filling time is 70-90s. The boost pressure is 1-1.2 kPa, the holding pressure is 1-1.5 kPa, and the holding time is 10-30s. The pressure must be released slowly, and it must not be released quickly. Unpacking and cleaning: The workpiece can be unpacked after it has cooled naturally for 2 hours, and the blank can be taken out.

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