Pouring system device for composite casting mold of screw rod casting of screw rod compressor rotor

Abstract

The utility model relates to a pouring system device for a composite casting mould of a rotor screw casting of a screw compressor, and belongs to the field of machinery. The pouring device comprises a molten iron filtering device, a sprue, main cross gates, forked cross gates, sunken ingates, inner gates and a slag accretion ring, the bottom of the sprue is provided with the two main cross gates, the tail ends of the two main cross gates are respectively provided with one forked cross gate, the lower portion of each forked cross gate is provided with a plurality of sunken ingates, and the lower portion of each sunken ingate is provided with a plurality of inner gates. Each sunken ingate is provided with an inner pouring gate, a molten iron filtering device is arranged on the main cross gate, and slag collecting rings are arranged at the upper end of an upper supporting shaft of the rotor screw and the upper end of the screw spiral tooth face shell mold. The casting system is reasonable in structural design and high in working efficiency, is suitable for a casting system of an iron mold sand coating-shell mold composite casting mold in vertical arrangement of one-mold multi-piece screw compressor rotor screw rod castings, and realizes large-batch mechanical production of one-mold multi-piece rotor screw rod castings.

Description

Technical Field

[0001] The utility model relates to a pouring system device for casting, in particular to a pouring system device for a composite mold of a rotor screw of a screw compressor, and belongs to the field of machinery. Background Art

[0002] A screw compressor is an efficient, energy-saving and low-noise gas compression and refrigeration device. Compared with the traditional piston-type gas compressor, it has the characteristics of simple structure, low exhaust temperature, large pressure ratio and high efficiency, and gradually replaces the traditional piston compressor. The screw compressor compresses gas through the meshing of two positive and negative rotors (hereinafter referred to as rotor screws) with spiral gear surfaces (see attached Figure 1 ) with each other.

[0003] At present, the production of rotor screw castings mainly still uses sand casting (wet molding sand or self-hardening resin sand), and the spiral gear surface mold cavity in the rotor screw is made by the way of manual rotation and mold lifting. The quality and production efficiency of rotor screws are relatively low, the rejection rate is high, and the production cost is high. With the improvement of the product quality of screw compressors and the continuous increase in demand, higher requirements are put forward for the material properties, axial balance and other performances of rotor screws. The existing production process and production form of rotor screw castings have become one of the bottlenecks in the development of screw compressors.

[0004] The iron mold coated with sand casting technology is an energy-saving, efficient, high-quality and green casting production technology. According to the structural characteristics and process requirements of rotor screw castings, by applying the iron mold coated with sand casting forming technology, combining with the shell mold forming technology of the spiral gear surface cavity of the rotor screw, and adopting the vertical casting forming process of rotor screw castings, the quality, comprehensive mechanical properties and casting production efficiency of rotor screw castings can be greatly improved.

[0005] In a Chinese patent with a publication date of March 17, 2023 and a publication number of CN115805289A, a utility model patent named "Investment Precision Casting Process for a Dry Screw Vacuum Pump Rotor" is disclosed. The patent includes the following steps: manufacturing a wax mold; applying a refractory coating to the outer wall of the wax mold and drying it to form a clay mold; inverting the clay mold and heating it to 90 - 175 °C to melt and drain the wax mold, forming a cavity in the clay mold; the main body of the cavity in the cavity is vertically arranged, one end of the runner is connected to the bottom of the cavity main body, and the other end is arranged higher than the cavity main body, the riser of the cavity is arranged on the upper side of the cavity main body and is connected to the top of the cavity main body; heating and firing the clay mold to form a ceramic mold; burying the ceramic mold in a sand box and pouring molten iron, and after the molten iron cools and solidifies, a casting is obtained. Although this utility model ensures smooth gas discharge in the cavity, thereby ensuring that the molten iron can fill the entire cavity, and the molten iron gradually flows upward along the spiral cavity, which can wash impurities to the riser, ensuring good forming effect of the rotor and uniform forming quality, the quality and production efficiency of the screw vacuum pump rotor are low, and the mold form and gating system are obviously completely different from those of this application.

[0006] Therefore, developing a gating system for an iron mold with sand coating - shell mold casting rotor screw casting suitable for the vertical arrangement of multiple rotor screws in one mold is one of the most important key technological links to meet the mass production of the vertical arrangement of the rotor screws in this mold. Utility Model Content

[0007] The purpose of the present utility model is to overcome the above - mentioned deficiencies existing in the prior art, and to provide a gating system device for a composite mold of a screw compressor rotor screw casting, which has a reasonable system design, is safe and reliable, has high production efficiency, has multiple rotor screws in one mold arranged vertically, and realizes the mass mechanized production of multiple rotor screws in one mold.

[0008] The technical solution adopted by the present utility model to solve the above problems is: The gating system device for the composite mold of the screw compressor rotor screw casting includes a molten iron filtering device, and is characterized in that: it further includes a sprue, a main runner, a bifurcated runner, a sunken ingate, an ingate and a slag - collecting ring. The bottom of the sprue is provided with two main runners, and at the end of each of the two main runners, a bifurcated runner is placed. Multiple sunken ingates are arranged below each bifurcated runner, and each sunken ingate is provided with an ingate. The molten iron filtering device is arranged on the main runner. A slag - collecting ring is arranged at the upper end of the upper support shaft of the rotor screw and at the upper end of the shell mold of the screw spiral tooth surface.

[0009] Preferably, a ceramic filter screen is provided in the molten iron filtering device of the present utility model. The molten iron fills the mold in the molten iron filtering device in a bottom-up manner through the ceramic filter screen; the molten iron is filled and filtered in an overflow manner, making the flow of the molten iron more stable. That is, the molten iron passes through the ceramic filter screen from bottom to top from the lower main runner and enters the upper main runner. This molten iron filling method makes the molten iron flow more smoothly during the filtering and slag blocking process, and the cross-sectional area of the molten iron passing through the ceramic mesh is more balanced.

[0010] Preferably, the number of the bifurcated runners and the number of the sunken ingates arranged on each bifurcated runner of the present utility model can be determined according to the size of the iron mold plane size and the size of the rotor screw.

[0011] Preferably, the main runner of the present utility model is distributed at the parting surface of the upper and lower molds.

[0012] Preferably, the cross-sectional ratios of each part of the gating system of the present utility model are: ∑ 直 :∑ 横 :∑ 内 =1:0.65 - 0.9:1.8 - 2.6.

[0013] Preferably, the gating system of the present utility model is arranged in a side-bottom gating manner.

[0014] Preferably, the slag collecting ring of the present utility model adopts an annular floating slag collecting ring.

[0015] Preferably, the heights of the slag collecting rings at the upper ends of the screw spiral tooth surface shell mold and the upper support shaft of the rotor screw of the present utility model are respectively controlled at 10 - 15 mm and 15 - 20 mm.

[0016] Compared with the prior art, the utility model has the following advantages and effects: 1) The whole system is reasonably designed, and can realize the casting production of multiple rotor screws in one mold of the iron mold with sand coating - shell mold composite mold, with high production efficiency; 2) It meets the high rigidity of the iron mold with sand coating - shell mold composite mold for rotor screw castings. Combining with the graphitization self-compensation effect in the iron mold with sand coating casting technology, riserless casting of rotor screw castings can be realized, and the casting process yield of rotor screw casting production is high; 3) In the upper and lower split molds, bottom gating is realized on the side of the lower support shaft of the rotor screw, so that the molten iron poured into the mold flows upward in the rotor screw mold. The molten iron flow is balanced and there is no splashing, greatly reducing casting defects such as iron beans, gas entrapment to form pores, and slag inclusion generated during the pouring process; 4) The molten iron foam ceramic filtering technology is adopted to avoid the primary slag defect in the internal structure of the casting; 5) The atmosphere exhaust device at the top of the cavity of the rotor screw casting ensures the smooth discharge of the gas generated during the pouring process of the iron mold with sand coating - shell mold composite mold; 6) The slag collecting layer at the top of the mold of the rotor screw casting floats and collects the secondary slag generated during the pouring of the molten iron, so that there are no casting defects such as slag inclusion in the casting body; 7) Realize the riserless and as-cast casting production of rotor screw castings, with remarkable energy-saving effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is an axonometric structural schematic diagram of a rotor screw casting in an embodiment of the utility model.

[0018] Figure 2 is a front view structural schematic diagram of a rotor screw casting in an embodiment of the utility model.

[0019] Figure 3 is a top view structural schematic diagram of a rotor screw casting in an embodiment of the utility model.

[0020] Figure 4 is a front view schematic diagram of the assembled composite mold of a rotor screw casting in an embodiment of the utility model.

[0021] Figure 5 is a top view schematic diagram of the assembled composite mold of a rotor screw casting in an embodiment of the utility model.

[0022] Figure 6 is a schematic diagram of the gating system of the composite mold of a rotor screw casting in an embodiment of the utility model Figure 1 .

[0023] Figure 7 is a schematic diagram of the gating system of the composite mold of a rotor screw casting in an embodiment of the utility model Figure 2 .

[0024] Figure 8 is a schematic diagram of the gating system of the composite mold of a rotor screw casting in an embodiment of the utility model Figure 3 .

[0025] Figure 9 It is a schematic diagram of the molten iron filtering device in the gating system of the composite mold for the rotor screw casting in the embodiment of the present utility model.

[0026] Figure 10 It is a schematic diagram of the integral shell mold of the spiral tooth surface in the composite mold for the rotor screw casting in the embodiment of the present utility model.

[0027] Figure 11 It is another schematic diagram of the integral shell mold of the spiral tooth surface in the composite mold for the rotor screw casting in the embodiment of the present utility model.

[0028] Figure 12 It is a schematic diagram of mold closing and locking of the composite mold for the rotor screw casting in the embodiment of the present utility model.

[0029] Figure 13 It is a schematic diagram of the gating system device of the composite mold for the rotor screw casting in the process of molten iron pouring and filling in the embodiment of the present utility model.

[0030] Figure 14 It is a schematic diagram of the process of solidification and cooling after the molten iron pouring and filling of the gating system device of the composite mold for the rotor screw casting in the embodiment of the present utility model.

[0031] Figure 15 It is a schematic diagram of the casting and gating system after the mold opening in the embodiment of the present utility model Figure 1 .

[0032] Figure 16 It is a schematic diagram of the casting and gating system after the mold opening in the embodiment of the present utility model Figure 2 .

[0033] In the figure: Rotor screw casting Z: Screw spiral tooth surface Z1, upper support shaft Z2, lower support shaft Z3, upper iron mold 11, lower iron mold 12, box buckle 13, sprue 1, main cross-riser 2, molten iron filtering device 3, bifurcated cross-riser 4, sunken ingate 5, ingate 6, slag trap ring 7, spiral tooth surface shell mold 8, outer circle surface 81 of the spiral tooth surface shell mold, bottom surface 82 of the spiral tooth surface shell mold, spiral tooth surface cavity 83, upper main cross-riser 21, lower main cross-riser 22, parting surface F, partial lower support shaft cavity S, molten iron flow direction L, draft angle A1 at the lower part of the parting surface F is 0.8° - 1°, draft angle A2 at the upper part of the parting surface F is 4° - 5°, the height H1 of the cavity of the lower support shaft Z3 is controlled within 15 - 25 mm, the shell mold thickness H2 is controlled within 8 - 12 mm, and H3 is controlled within 20 - 40 mm. Specific embodiments

[0034] The present utility model will be further described in detail below in conjunction with the accompanying drawings and through embodiments. The following embodiments are explanations of the present utility model, and the present utility model is not limited to the following embodiments.

[0035] Embodiment

[0036] See Figures 1 to 16 , the gating system device of the compound mold for the rotor screw casting of the screw compressor in this embodiment includes a sprue 1, a main runner 2, a molten iron filtering device 3, a bifurcated runner 4, a sunken ingate 5, an ingate 6, and a slag trap ring 7. Two main runners 2 are arranged at the bottom of the sprue 1. One bifurcated runner 4 is placed at the end of each of the two main runners 2. Multiple sunken ingates 5 are arranged below each bifurcated runner 4. An ingate 6 is arranged on each sunken ingate 5. Slag trap rings 7 are arranged at the upper ends of the upper support shaft of the rotor screw and the upper end of the shell mold of the screw spiral tooth surface. The molten iron filtering device 3 is arranged on the main runner 2.

[0037] The casting production of the rotor screw casting Z adopts an iron mold with sand coating and shell mold composite mold. Its structural form is: all the cavities of the rotor screw casting Z in the mold are arranged axially perpendicular. Among them, the upper support shaft Z2 and the lower part of the lower support shaft Z3 of the rotor screw adopt iron mold with sand coating, and the screw spiral tooth surface Z1 of the rotor screw and part of the lower support shaft Z3 adopt shell mold, so that the mold of the rotor screw combines the advantages of iron mold with sand coating and shell mold (see the appendix Figures 4 - 5 ). According to the structural characteristics, process requirements, and performance requirements of the mold of this rotor screw, the gating system in this embodiment is set in the way of side-bottom pouring. Its structural form is shown in the appendix Figures 6 - 8 , including the sprue 1, the main runner 2, the molten iron filtering device 3, the bifurcated runner 4, the sunken ingate 5, the ingate 6, and the slag trap rings 7 at the upper end of the upper support shaft Z2 of the rotor screw and the upper end of the spiral tooth surface shell mold 8.

[0038] This embodiment is a gating system device for a one-type multi-piece rotor screw casting using an iron mold with sand coating and a shell mold composite mold. The process principle is as follows: The rotor screw is arranged vertically axially, which can well ensure the axial dynamic balance performance of the rotor screw casting. For the casting process of the rotor screw arranged vertically axially, the desired gating process is the bottom gating form. This gating method can well make the molten iron poured into the mold fill the mold smoothly from bottom to top, and at the same time make the inclusions in the molten iron float well, so as to obtain high-quality castings without defects. However, for the iron mold with sand coating - shell mold composite mold, generally there are only two upper and lower molds, so the parting surface of the mold is generally the mating surface of the upper and lower molds. For the mold of the rotor screw casting in this embodiment, the parting surface of the iron mold is in the middle part of the spiral tooth surface of the rotor screw. If the water inlet position of the ingate 6 of the gating system is arranged at this position, the molten iron is injected from the middle position of the rotor screw. For the filling of the molten iron, the filling of the molten iron is relatively unstable, and it is not conducive to the floating of inclusions in the molten iron, nor is it conducive to using the process advantages of the iron mold with sand coating casting to achieve riserless casting production of the rotor screw casting. The gating system device of this embodiment utilizes the structural characteristics of the iron mold with sand coating and the shell mold composite mold. By improving the shell mold structure of the spiral tooth surface of the rotor screw, a sunken ingate runner 5 and an ingate 6 are embedded between the contact surface of the iron mold with sand coating cavity and the shell mold; the molten iron overflows and passes through a ceramic filter screen to filter the molten iron, making the filling of the molten iron more stable; slag collecting rings 7 are arranged at the top of the spiral tooth surface of the rotor screw and at the top of the upper support shaft, and the forms of balanced solidification and riserless self-feeding are adopted to form the bottom-side gating system device of the rotor screw casting in this embodiment, so as to realize the riserless, high-quality and high-efficiency production of the rotor screw casting using the iron mold with sand coating and the shell mold composite mold.

[0039] The gating system device of this embodiment is a semi-closed gating system, and the ratio of each cross-section is: ∑ 直 :∑ 横 :∑ 内 =1:0.65 - 0.9:1.8 - 2.6, to ensure that the molten iron of the gating system in this embodiment has a good slag blocking effect and a stable filling effect during the pouring process. As shown in the appendix Figures 6 - 8As shown in the figure: The bottom of the sprue 1 is divided into two parts, with two main cross-risers 2 branching out to the left and right; above the ends of the two main cross-risers 2, a molten iron filtering device 3 is installed respectively. The molten iron poured in passes through the ceramic filter screen in the form of overflow filling, filtering the slag of the molten iron while ensuring the steady flow of the filling molten iron; above each ceramic filter screen, a section of the main cross-riser 2 is connected, and at the end of this main cross-riser 2, a bifurcated cross-riser 4 is placed respectively; under each bifurcated cross-riser 4, multiple sunken ingates 5 can be set according to the size of the mold area. The ingate 6 of each sunken ingate 5 corresponds to the mold of a rotor screw casting, and the molten iron will enter the lower side of the lower support shaft Z3 of the rotor screw through the ingate 6. To make the molten iron entering each rotor screw mold enter the mold from the bottom side of the lower support shaft Z3 of the rotor screw, the upper end of the spiral tooth surface cavity 83 of the spiral tooth surface shell mold 8 of the rotor screw is in an open form, and the lower end of the spiral tooth surface cavity 83 of the spiral tooth surface shell mold 8 of the rotor screw is in a closed form, that is: a part of the cavity of the support shaft at the lower end of the spiral tooth surface cavity 83 is made on the overall shell mold of the rotor screw spiral tooth surface Z1 (see attachment Figures 10 - 11 ), and the height dimension H3 of the cavity S of the lower support shaft in the middle part of the shell mold is controlled to be between 20 and 40 mm according to the size of the rotor screw and the length of the lower support shaft, so as to ensure that the position of the ingate 6 of the gating system in this embodiment is in the lower cavity of the lower support shaft Z3 of the rotor screw. To realize the water inlet of the ingate at the lower part of the lower support shaft of the rotor screw, a part of the lower support shaft cavity is formed at the lower part of the spiral tooth surface shell mold of the rotor screw (attachment Figures 10 - 11 ), and the height H1 of the cavity of the iron mold with coated sand for the lower support shaft Z3 is controlled to be between 15 and 25 mm (see attachment Figures 4 - 5 ).

[0040] The bottom of the composite mold of the rotor screw with iron mold coated with sand and shell mold adopts the side-bottom gating method. The main cross-riser 2 in the gating system is distributed at the parting surface of the upper and lower molds, and the ingate 6 enters the lower side of the lower support shaft of the rotor screw through the sunken runner 5 and sinks.

[0041] The mold cavity of the screw spiral tooth surface Z1 is formed in the inner cavity of the shell mold. The shell thickness at the thinnest part of the spiral tooth surface shell mold 8 is controlled to be between 8 and 12 mm. The draft angle A1 of the outer conical surface of the spiral tooth surface shell mold 8 below the parting surface F is 0.8° - 1°, and the draft angle A2 above the parting surface F is 4° - 5°. At the uppermost end of the open-type cavity at the upper end of the screw spiral tooth surface Z1 of the spiral tooth surface shell mold 8, a slag collecting ring 7 with a length of 10 - 15 mm is made (see attachment Figures 4 - 5 , attachment Figures 10 - 11 ), which is used for the floating and aggregation of secondary slag generated during the pouring process, ensuring the quality of the upper part of the rotor screw spiral tooth surface. At the top of the upper support shaft Z2 of the rotor screw, a slag collecting ring 7 with a length of 15 - 20 mm is made, which is used for the floating and aggregation of secondary slag at the top of the upper support shaft Z2.

[0042] The molten iron fills the mold of the molten iron filtering device 3 in a bottom-up filling manner (molten iron overflow filling filtration) through a ceramic filter screen (attached Figure 9 ). That is, the molten iron passes from the lower main runner 22 through the ceramic filter screen in the molten iron filtering device 3 from bottom to top and enters the upper main runner 21. This molten iron filling method makes the molten iron flow more smoothly during the filtration and slag blocking process, and the cross-sectional area of the molten iron passing through the ceramic mesh is more balanced.

[0043] As attached Figures 4 - 5 、attached Figures 6 - 8 shown: The sprue 1, main runner 2, bifurcated runner 4, and molten iron filtering device 3 in this embodiment are made in the iron mold with sand coating; three of the four surfaces of the cavity such as the sunken ingate 5 and ingate 6 are formed in the iron mold with sand coating, and the remaining one surface is formed on the outer side and bottom surface of the rotor screw spiral tooth surface shell mold 8. The number of bifurcated runners 4 and the number of sunken ingates 5 arranged on each bifurcated runner 4 can be determined according to the size of the iron mold plane and the size of the rotor screw. That is, in a set of rotor screw composite molds, the number of bifurcated runners 4 can be 2, 4, 6... etc., and the number of sunken ingates 5 arranged on one bifurcated runner 4 can also be 2, 4, 6, 8... etc. In the mold cavity of each rotor screw, the slag collecting ring 7 cavity is made in the upper open cavity of the rotor screw spiral tooth surface shell mold 8 and on the top of the upper support shaft Z2.

[0044] The form in which the sunken ingate 5 and ingate 6 cavities are formed in the iron mold with sand coating and shell mold composite mold of this gating system: Among the four surfaces of the sunken ingate 5 cavity: three of them are formed in the iron mold with sand coating cavity, and one surface is formed on the outer cylindrical surface of the rotor screw spiral tooth surface shell mold; among the four surfaces of the ingate cavity: three of them are formed in the iron mold with sand coating cavity, and one surface is formed on the bottom surface of the rotor screw spiral tooth surface shell mold (see attached Figures 10 - 11 ).

[0045] In this embodiment, box buckles 13 are also connected to the upper iron mold 11 and the lower iron mold 12, and the slag collecting ring 7 adopts an annular floating slag collecting ring.

[0046] During the production process of the rotor screw casting in this embodiment, the process of pouring molten iron into the iron mold with sand coating and shell mold composite mold is as attached Figures 12 - 16As shown, the molten iron for casting enters the sprue 1 through the pouring basin, and then divides into two parts and enters the main runner 2 at the bottom of the sprue 1. The molten iron then passes upward through the molten iron filtering device 3 provided on the main runner 2 to remove slag and filter the molten iron, and make the molten iron fill the mold smoothly. Then the molten iron fills the forked runner 4, and then enters each sunken ingate 5. The molten iron fills downward through the sunken ingate 5 formed by the iron mold with coated sand and the shell mold, and enters the ingate 6 formed by the iron mold with coated sand and the shell mold. The molten iron enters the lower side of the cavity of the lower support shaft Z3 of the rotor screw, and fills the casting cavity of the rotor screw from bottom to top until the entire casting cavity of the rotor screw is filled, completing one pouring of the rotor screw casting; during the pouring process, the secondary slag generated in the mold floats up and finally accumulates in the slag collecting ring 7 at the upper end of the screw spiral tooth surface Z1 and the slag collecting ring 7 at the top of the upper support shaft Z2 during the cooling and solidification process of the molten iron; then the molten iron solidifies in the mold, and the self-compensation shrinkage of the molten iron is realized by using the graphitization expansion during the solidification process, achieving riserless casting of the rotor screw casting. After cooling to a certain temperature, the mold is opened and the casting is taken out, and finally one casting production of the rotor screw is completed.

[0047] In this embodiment, according to the process requirements of the rotor screw casting of the screw compressor in the vertical arrangement in the iron mold with coated sand and shell mold composite mold, and the characteristics of the iron mold with coated sand casting process, in the upper and lower split molds, the gating system process is set with a molten iron runner filtering device, a horizontal multi-branch structure, and the ingate enters the side of the lower support shaft of the rotor screw through a vertically falling sprue, so that the molten iron enters the casting cavity of the rotor screw in a bottom-side pouring manner from the side of the lower support shaft of the rotor screw. The gating system forms a bottom-side pouring riserless self-compensation shrinkage form, a floating slag layer of molten iron inclusions at the top of the mold, an exhaust device, etc. During the pouring process, the molten iron rises smoothly, avoiding casting defects such as iron bean splashing, gas entrapment, slag inclusion, shrinkage porosity, etc. during the molten iron pouring process of the rotor screw casting.

[0048] Through the above description, those skilled in the art can already implement it.

[0049] In addition, it should be noted that for the specific embodiments described in this specification, the shapes and names of the parts and components can be different. The above content described in this specification is only an example of the structure of the present invention. Any equivalent changes or simple changes made according to the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. Those skilled in the technical field to which the present invention belongs can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, as long as they do not deviate from the structure of the present invention or exceed the scope defined by this claim book, they should belong to the protection scope of the present invention.

Claims

1. A casting system device for a composite casting mold of a screw compressor rotor screw casting, comprising a molten iron filtering device (3), characterized in that: It also includes a straight runner (1), a main cross runner (2), a forked cross runner (4), a sunken ingrate (5), an ingrate (6) and a slag gathering ring (7), characterized in that: two main cross runners (2) are arranged at the bottom of the straight runner (1), a forked cross runner (4) is placed at the end of each of the two main cross runners (2), a plurality of sunken ingrates (5) are arranged below each forked cross runner (4), each sunken ingrate (5) is provided with an ingrate (6), a molten iron filtering device (3) is arranged on the main cross runner (2), and a slag gathering ring (7) is arranged at the upper end of the upper support shaft of the rotor screw and the upper end of the screw spiral tooth surface shell.

2. The pouring system device for the composite casting mold of the screw compressor rotor screw casting according to claim 1, characterized in that: The molten iron filtering device (3) is provided with a ceramic filter screen, and the molten iron is filled in the molten iron filtering device (3) by passing through the ceramic filter screen from bottom to top.

3. The pouring system device of the composite casting mold of the screw compressor rotor screw casting according to claim 1, characterized in that: The number of the bifurcated cross runners (4) and the number of sunken ingates (5) arranged on each bifurcated cross runner (4) can be determined according to the size of the plane dimensions of the iron mold and the size of the rotor screw.

4. The pouring system device for the composite casting mold of the screw compressor rotor screw casting according to claim 1, characterized in that: The main runner (2) is distributed at the parting surface of the upper and lower casting molds.

5. The pouring system device for the composite casting mold of the screw compressor rotor screw casting according to claim 1, characterized in that: The cross-sectional ratio of the gating system is: 直 :∑ 横 :∑ 内 =1:0.65-0.9:1.8-2.

6.

6. The pouring system device for the composite casting mold of the screw compressor rotor screw casting according to claim 1, characterized in that: The pouring system is set up by side and bottom pouring.

7. The pouring system device for the composite casting mold of the screw compressor rotor screw casting according to claim 1, characterized in that: The slag collecting ring (7) is an annular floating slag collecting ring.

8. The pouring system device for the composite casting mold of the screw compressor rotor screw casting according to claim 1, characterized in that: The heights of the slag gathering ring (7) at the upper end of the spiral tooth surface shell of the screw and the upper end of the upper support shaft of the rotor screw are controlled to be 10-15 mm and 15-20 mm respectively.

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