Twin screw compressor housing casting model

Abstract

A kind of double screw compressor shell casting model, including model body, main sprue, a pair of branch sprues, a pair of gates, a pair of first risers and multiple second risers.Model body is identical with double screw compressor shell shape;Model body includes air inlet end face and exhaust end face opposite to each other, and 8-shaped hole extending along the axial direction of model body, 8-shaped hole includes male rotor hole and female rotor hole.Main sprue is connected with the top of a pair of gates respectively through a pair of branch sprues, at least a part of a pair of gates respectively extends into male rotor hole and female rotor hole from the side of air inlet end face of model body, a pair of first risers are connected with the bottom of a pair of gates respectively;Each gate has first side face and second side face opposite to each other, first side face and second side face are connected with the hole wall of corresponding rotor hole respectively;Multiple second risers are connected with exhaust end face respectively, and surround around 8-shaped hole.This utility model can reduce casting defects of casting product.

Description

Technical Field

[0001] This utility model relates to the field of compressor technology, and in particular to the casting technology of twin-screw compressor housing. Background Technology

[0002] The casing material of the screw compressor is a martensitic stainless steel casting. This martensitic stainless steel casting has the characteristics of high melting point, easy oxidation and poor fluidity. During the casting process, defects such as cracks, shrinkage cavities, shrinkage porosity and deformation are prone to occur, thus affecting the quality of the casting.

[0003] To prevent the aforementioned defects, risers are typically placed at different locations during the molding and casting process, depending on the specific structure and shape of the casting. Riseres primarily serve four functions: 1. Feeding: Because risers store a certain amount of molten steel, they continuously replenish the molten steel during the final solidification stage of the casting, preventing shrinkage cavities and porosity; 2. Slag removal: Risers are usually designed in higher and thicker sections, allowing lighter slag and non-metallic inclusions to float into the riser, reducing inclusions, porosity, and sand holes; 3. Venting: Open risers act as large vents during casting, allowing gases released from the sand mold and molten steel to escape; 4. Assessing casting conditions: The rising of molten steel within the riser allows observation of the casting status, enabling control of the casting speed and time.

[0004] Figure 1 and Figure 2 A schematic diagram of a casting model of an existing twin-screw compressor housing is shown. (As shown) Figure 1 As shown, the casting model uses side casting, with an exposed riser 43a designed on the side and a concealed riser 44a designed inside the casting model. During casting, molten steel flows into the sand mold through the gating system 3a, and slag inclusions and gases are discharged through the riser. After cooling and heat preservation, the gating system and riser are removed to obtain the casting blank. In subsequent processing, numerous defects are frequently found in the figure-eight holes and two end faces inside the twin-screw compressor housing. The interior of the twin-screw compressor housing typically exhibits defects such as cracks and shrinkage cavities, while the end faces typically exhibit defects such as shrinkage porosity, gas porosity, and slag inclusions. Based on the design function of the riser, the inventors believe that the unreasonable design of the riser structure in the prior art leads to casting defects. In the prior art, the exposed riser 43a is located at the top of the side of the casting model, resulting in poor slag removal and venting performance on the side during casting, leading to shrinkage porosity and slag inclusions at the machined area of ​​the cylinder face. The number and size of the hidden risers 44a inside the figure-eight hole are unreasonable. During the solidification process of the casting, the hidden risers 44a cannot fully provide internal feeding and heat to allow the casting to cool slowly, resulting in the shrinkage of the casting blank during cooling and the generation of cold cracks. Summary of the Invention

[0005] The technical problem to be solved by this utility model is to provide a casting model for a twin-screw compressor housing, which can reduce casting defects and improve the quality of casting products.

[0006] This utility model provides a casting model of a twin-screw compressor housing, including a model body with the same shape as the twin-screw compressor housing. The model body includes an intake end face and an exhaust end face opposite to each other, and a figure-eight hole extending axially along the model body and penetrating the intake end face and the exhaust end face. The figure-eight hole includes a male rotor hole and a female rotor hole. The model is characterized in that it includes a main runner, a pair of branch runners, a pair of gates, a pair of first risers, and multiple second risers. The main runner is connected to the top of the pair of gates via the pair of branch runners. At least a portion of the pair of gates extends from the intake end face of the model body into the male rotor hole and the female rotor hole, respectively. The pair of first risers are connected to the bottom of the pair of gates. Each gate has a first side face and a second side face opposite to each other, and the first side face and the second side face are connected to the hole wall of the corresponding rotor hole. The multiple second risers are connected to the exhaust end face and surround the figure-eight hole.

[0007] This utility model has at least the following advantages and features:

[0008] 1. In this embodiment of the utility model, a pair of first risers are respectively set at the bottom of a pair of gates, and multiple second risers are respectively set at the vent end face. Since the risers are not set at the junction of thick and thin sections, stress concentration is reduced and crack defects are avoided in the casting product during the cooling process.

[0009] 2. In this embodiment of the invention, the second riser is located on the venting plane that requires machining, making it easy to clean; while the exposed riser of the existing casting model is located on the outer curved rib plate, which increases the difficulty of cleaning the riser.

[0010] 3. In this embodiment of the utility model, most of the pair of gates are located inside the figure-eight holes, so that they do not directly impact the sand mold body during casting, thus reducing the risk of sand inclusion defects caused by high-temperature molten steel impacting the sand mold.

[0011] 4. In this embodiment of the invention, a first riser is provided at the bottom of each pair of gates, which improves the feeding efficiency and allows for sufficient feeding during the solidification process of the casting, preventing defects such as shrinkage cavities.

[0012] 5. In this embodiment of the utility model, the pair of gates and the first riser are of large size. The large-sized riser plays a role in heat preservation and slow cooling during the cooling process, preventing defects such as cold cracks and shrinkage porosity from occurring when the casting is cooled. Attached Figure Description

[0013] Figure 1A schematic diagram of the appearance of a casting model of an existing twin-screw compressor housing is shown.

[0014] Figure 2 A cross-sectional schematic diagram of a casting model of an existing twin-screw compressor housing is shown.

[0015] Figures 3 to 6 The diagrams show the structural schematics of a casting model of a twin-screw compressor housing according to an embodiment of the present invention from different angles. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] Figures 3 to 6 A casting model of a twin-screw compressor housing according to an embodiment of the present invention is shown. Please refer to... Figures 3 to 6 According to an embodiment of the present invention, the casting model of a twin-screw compressor housing includes a model body 1, a main gating system 21, a pair of branch gating systems 22, a pair of gating gates 3, a pair of first risers 41, and a plurality of second risers.

[0018] The model body 1 has the same shape as the housing of a twin-screw compressor. The model body 1 includes an intake end face 11 and an exhaust end face 12 that are opposite to each other, and an 8-shaped hole 10 that extends along the axial direction of the model body 1 and passes through the intake end face 11 and the exhaust end face 12. The 8-shaped hole 10 includes a male rotor hole 101 and a female rotor hole 102.

[0019] The model body 1 includes a main body 1c and an intake flange 1a and an exhaust flange 1b located at both axial ends of the main body 1c. The sides of the main body 1c are provided with multiple axially spaced reinforcing ribs 14c, each extending along the axial direction of the main body 1c, with both ends connected to the intake flange 1a and the exhaust flange 1b, respectively. Between each pair of adjacent axially spaced reinforcing ribs 14c are multiple axially spaced arc-shaped reinforcing ribs 15c, each extending along the circumferential direction of the main body 1c and connected to the side of the main body 1c, with both ends connected to the axially spaced reinforcing ribs 14c.

[0020] Preferably, the model body 1 is a martensitic stainless steel casting, and its material is ZG15Cr13.

[0021] The main runner 21 is connected to the top of a pair of gates 3 via a pair of branch runners 22. At least a portion of the pair of gates 3 extends from the air intake end face of the model body 1 into the male rotor hole 101 and the female rotor hole 102 respectively. A pair of first risers 41 are connected to the bottom of the pair of gates 3 respectively.

[0022] In this embodiment, the main runner 21 is inverted L-shaped and includes a first vertical runner 211 and a first horizontal runner 212. The first vertical runner 211 is located on the outside of the model body 1. The top end of the first vertical runner 211 is connected to the first end of the first horizontal runner 212, and the second end of the first horizontal runner 212 is connected to a pair of branch runners 22. The branch runners 22 are inverted L-shaped and include a second vertical runner 221 and a second horizontal runner 222. The first end of the second horizontal runner 222 is connected to the second end of the first horizontal runner 212, the second end of the second horizontal runner 222 is connected to the top end of the second vertical runner 221, and the bottom end of the second vertical runner 221 is connected to the top of the corresponding gate.

[0023] Each gate 3 has a first side 31 and a second side 32 facing each other, and the first side 31 and the second side 32 are respectively connected to the bore wall of the corresponding rotor hole. In this embodiment, a pair of gates 3 partially extend into the figure-eight hole 10. The pair of gates 3 are identical in shape and size, and the length of each gate 3 is half the axial length of the figure-eight hole 10. In other embodiments, the entire pair of gates 3 extend into the figure-eight hole 10.

[0024] In this embodiment, the pair of first risers 41 are identical in shape and size. Each first riser 41 has a circular cross-section, and its length is 1.2 times its outer diameter. The length of the first riser 41 refers to its axial length.

[0025] Multiple second risers are connected to the vent end face 12 and surround the figure-eight hole 10. In this embodiment, there are six second risers. Two of the second risers 42a and 42b have circular cross-sectional shapes. The two second risers 42a and 42b with circular cross-sections are identical in shape and size, and the length of each second riser with a circular cross-section is 1.2 times its outer diameter. The remaining four second risers 42c, 42d, 42e, and 42f have waist-shaped cross-sections (the outline of the waist-shaped section includes two parallel straight line segments of equal length and two semicircular arcs connected to the ends of the two straight line segments). Three of these waist-shaped second risers, 42d, 42e, and 42f, have the same shape and size. The remaining waist-shaped second riser has a larger semicircular diameter than the other three waist-shaped risers 42d, 42e, and 42f, and the length of each waist-shaped second riser is 1.2 times its own semicircular diameter. Two circular second risers 42a and 42b are located directly on either side of the second riser 42c, which has the largest semicircular diameter. The aforementioned semicircular diameter refers to the diameter of the semicircular arc of the waist-shaped section.

[0026] In some specific implementations, the outer diameters of the two second risers 42a and 42b are equal to the semicircular diameters of the waist-shaped second risers 42d, 42e and 42f.

[0027] In the example shown in the figure, the tops of each first riser and each second riser are tapered in size. In other embodiments, the tops of each first riser and each second riser may also be completely consistent with the shape of the main body, that is, adopt a standard cylindrical or waist-shaped column.

[0028] When casting the twin-screw compressor housing using the casting model of this utility model embodiment, vertical bottom casting (bottom casting) is adopted. A sufficient number of chills are set on the bottom surface of the sand mold for forced cooling. The solidification sequence of the molten steel is controlled to ensure that the casting solidifies towards the riser. The solidification time of the riser is longer than that of the casting, and the casting as a whole receives sufficient feeding.

[0029] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. A casting model of a twin-screw compressor housing, comprising a model body having the same shape as the twin-screw compressor housing; the model body comprising an inlet end face and an exhaust end face opposite to each other, and an 8-shaped hole extending axially along the model body and penetrating the inlet end face and the exhaust end face, the 8-shaped hole comprising a male rotor hole and a female rotor hole; characterized in that, The twin-screw compressor housing casting model includes a main runner, a pair of branch runners, a pair of gates, a pair of first risers, and multiple second risers; The main runner is connected to the top of a pair of gates via a pair of branch runners. At least a portion of the pair of gates extends from the air intake end face of the model body into the male rotor hole and the female rotor hole, respectively. The pair of first risers are connected to the bottom of the pair of gates. Each gate has a first side and a second side opposite to each other. The first side and the second side are connected to the hole wall of the corresponding rotor hole, respectively. The plurality of second risers are respectively connected to the exhaust end face and surround the figure-eight hole.

2. The twin-screw compressor housing casting model according to claim 1, characterized in that, The main gating system is inverted L-shaped, including a first vertical gating system and a first horizontal gating system; The first vertical sprue is located on the outside of the model body. The top end of the first vertical sprue is connected to the first end of the first horizontal sprue, and the second end of the first horizontal sprue is connected to the pair of branch sprues respectively.

3. The twin-screw compressor housing casting model according to claim 2, characterized in that, Each of the branch runners is inverted L-shaped, including a second vertical runner and a second horizontal runner; The first end of the second horizontal sprue is connected to the second end of the first horizontal sprue, the second end of the second horizontal sprue is connected to the top end of the second vertical sprue, and the bottom end of the second vertical sprue is connected to the top of the corresponding gate.

4. The twin-screw compressor housing casting model according to claim 1, characterized in that, The pair of gates are identical in shape and size.

5. The twin-screw compressor housing casting model according to claim 1 or 4, characterized in that, The length of each gate is half the axial length of the figure-eight hole.

6. The twin-screw compressor housing casting model according to claim 1, characterized in that, The pair of first risers are identical in shape and size.

7. The twin-screw compressor housing casting model according to claim 1 or 6, characterized in that, The cross-sectional shape of each first riser is circular, and the length of each first riser is 1.2 times the outer diameter of the first riser.

8. The twin-screw compressor housing casting model according to claim 1, characterized in that, The number of the second riser is six.

9. The twin-screw compressor housing casting model according to claim 8, characterized in that, Two of the second risers have circular cross-sectional shapes. The two second risers with circular cross-sections are identical in shape and size, and the length of each second riser with a circular cross-section is 1.2 times its outer diameter. The remaining four second risers have an oblong cross-section. Three of the oblong second risers have the same shape and size. The diameter of the oblong semicircle of the remaining oblong second riser is larger than the diameter of the oblong semicircle of the three oblong second risers. The length of each oblong second riser is 1.2 times the diameter of its own oblong semicircle. Two second risers with circular cross-sections are located directly on either side of the second riser with the largest diameter in the waist-shaped semicircle.

10. The twin-screw compressor housing casting model according to claim 1, characterized in that, The model body includes a main body and an air inlet flange and an exhaust flange located at both axial ends of the main body; The side of the main body is provided with multiple axial reinforcing ribs that are spaced apart in the circumferential direction. Each axial reinforcing rib extends along the axial direction of the main body, and both ends of each axial reinforcing rib are connected to the air inlet flange and the exhaust flange, respectively. Between each pair of adjacent axial stiffening plates, there are multiple arc-shaped stiffening ribs distributed at intervals along the axial direction. Each arc-shaped stiffening rib extends along the circumferential direction of the main body and is connected to the side of the main body. The two ends of each arc-shaped stiffening rib are connected to the axial stiffening plate respectively.

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