Device for casting rotor screw rod casting of large screw rod compressor

Abstract

The utility model relates to a device for casting a rotor screw rod casting of a large screw rod compressor, and belongs to the field of machinery. The casting mold comprises a box locking screw rod used for locking and fixing an upper iron mold casting mold and a lower iron mold casting mold, an iron mold sand-coated casting mold cavity and a precoated sand shell mold cavity, a pouring system is arranged in the upper iron mold casting mold and the lower iron mold casting mold, the pouring system is arranged in a bottom pouring mode, and the pouring system comprises a pouring cup and a sprue which are connected. The sprue cup and the sprue cavity are axially and horizontally arranged in the upper iron mold casting mold and the lower iron mold casting mold; the arrangement of the sprue cup and the sprue cavity in the upper iron mold casting mold and the lower iron mold casting mold and the arrangement of the rotor screw casting casting mold cavity are both axially and horizontally arranged. The rotor screw axial dynamic balance device is reasonable in structural design, safe, reliable, high in casting process yield and simple in production process control, guarantees the rotor screw axial dynamic balance performance, achieves batch production of large rotor screw castings, and meets use requirements.

Description

Technical Field

[0001] The utility model relates to a device, in particular to a device for casting large screw compressor rotor screw castings, which is suitable for axial vertical bottom pouring of large screw compressor rotor screw castings in an iron mold covered with sand-shell composite mold casting form, and belongs to the field of machinery. Background Art

[0002] The screw compressor uses two forward and reverse rotors with helical gear surfaces (hereinafter referred to as: rotor screw) (see Figure 1-Figure 3 ) mesh with each other to compress the gas. Screw compressors are highly efficient, energy-saving, and low-noise gas compression and refrigeration devices. They feature a simple structure, low exhaust temperature, a large gas compression ratio, and high efficiency. The trend is gradually evolving from small rotor screw compressors to large rotor screw compressors, and they hold great promise for future applications.

[0003] The production of large rotor screw castings currently still uses sand casting (green sand or self-hardening resin sand). A three-open mold or multi-open mold method is used, and the spiral tooth surface casting cavity in the rotor screw is produced by manual rotary demolding or multi-block demolding. A large amount of chiller is required in the mold, and the molten iron in the mold is fed by the provision of risers. The production process is relatively complex, the rotor screw quality and production efficiency are relatively low, the scrap rate is high, and the production cost is high. In addition, due to the slow heat transfer of ordinary sand molds, the poor mold rigidity, and some limitations of the sand casting process, it is difficult for the internal structure and mechanical properties of large rotor screw castings to meet product requirements. The existing production process and production methods of large rotor screw castings (weighting 400-600 kg, length of about 1000 mm, and maximum diameter of the screw spiral tooth surface of about 350-450 mm) have become one of the bottlenecks in the development of large screw compressors.

[0004] Iron mold sand-coated casting technology is an energy-saving, efficient, high-quality, and green casting production technology with the characteristics of fast cooling speed and high casting mold rigidity. According to the structural characteristics and process requirements of rotor screw castings, the iron mold sand-coated casting forming technology is used, combined with the shell mold forming technology of the spiral gear surface cavity of the rotor screw. Through the reasonable planning of the casting form of large rotor screws, the bottom-pouring axial vertical riser-free casting production of large rotor screws can be realized in a single-open mold.

[0005] Therefore, it is particularly necessary to provide an iron mold sand-shell casting rotor screw casting production process mode suitable for axial horizontal molding and axial vertical pouring of large rotor screw castings to achieve high-quality and mass production of large rotor screw castings. Utility Model Content

[0006] The purpose of the present utility model is to overcome the above-mentioned shortcomings of the prior art and to provide a device for casting large screw compressor rotor screw castings, which has a reasonable structural design, is safe and reliable, has a high casting process yield, has simple production process control, ensures the axial dynamic balance performance of the rotor screw, and realizes the mass production of large rotor screw castings.

[0007] The technical solution adopted by the utility model to solve the above-mentioned problems is: the device for casting large-scale screw compressor rotor screw castings includes a lock box screw for locking and fixing the upper iron mold casting and the lower iron mold casting, and is characterized in that it also includes an upper support shaft, a lower support shaft casting cavity, a rotor screw spiral tooth surface shell backing cavity, an iron mold sand casting cavity for forming the rotor screw casting, and a coated sand shell cavity for forming the screw spiral tooth surface casting cavity of the rotor screw casting, the casting system is arranged in the upper iron mold casting and the lower iron mold casting, the casting system is arranged in the form of bottom pouring, the casting system includes a connected pouring cup and a straight runner, the pouring cup and the straight runner cavity are arranged in the upper iron mold casting and the lower iron mold casting in an axial horizontal arrangement; the arrangement of the pouring cup and the straight runner cavity in the upper iron mold casting and the lower iron mold casting is axially horizontal with the arrangement of the rotor screw casting cavity.

[0008] Preferably, the rotor screw casting of the present invention is a two-piece casting in an iron mold, with half of the circular rotor screw casting cavity arranged in the upper iron mold and the other half arranged in the lower iron mold.

[0009] Preferably, the present invention further comprises a ceramic filter screen, which is horizontally arranged in the sand-covered molding cavity in the lower iron mold.

[0010] Preferably, the pouring cup of the present invention is communicated with the sprue, and half of the conical cavity of the pouring cup is arranged in the upper iron mold, and the other half of the conical cavity is arranged in the lower iron mold.

[0011] Preferably, the pouring system of the present invention further comprises a horizontal runner, which is connected to the sprue, a semicircular cavity of the sprue is arranged in the upper iron mold, and the other semicircular cavity of the sprue is arranged in the lower iron mold.

[0012] Preferably, the pouring system of the present invention also includes an endogate, an air vent riser, a riser runner and an air vent needle. The cross-sectional shape of the endogate is circular, with the upper iron mold and the lower iron mold each occupying a semicircle; the air vent riser and the air vent needle are both circular; the cross-sectional shape of the riser runner is rectangular, with the upper iron mold and the lower iron mold cavity each occupying half.

[0013] Preferably, the diameter of the gas outlet riser of the present invention is determined according to the size of the rotor screw casting, and the diameter of the gas outlet needle is controlled to be between 15 and 20 mm according to the size of the rotor screw casting.

[0014] Preferably, the pouring cup of the present invention is a conical pouring cup, which is made directly in the upper iron mold and the lower iron mold, with the iron mold parting surface as the boundary, and the upper iron mold and the lower iron mold cavity each occupy half.

[0015] Compared with the prior art, the utility model has the following advantages and effects: 1) The overall structural design is reasonable, safe and reliable, and meets the high rigidity of the iron mold sand-shell composite casting of large rotor screw castings and good casting cooling performance. Combined with the graphitization self-feeding effect in the iron mold sand-covered casting technology, the liquid feeding amount of the rotor screw casting can be greatly reduced. At the same time, the high-temperature molten iron in the gas outlet has a strong feeding effect, and the casting process for the production of rotor screw castings has a high yield rate; 2) The large rotor screw casting mold adopts horizontal sand-covered molding, the rotor screw spiral tooth surface shell mold and the molten iron filter are placed horizontally, and the box is closed horizontally. The molding and closing processes of the mold are convenient and fast, and it is easy to realize mechanized work Industry; 3) After the box is closed and locked, the mold is flipped 90°, which can realize vertical bottom pouring of large rotor screw castings. The molten iron poured into the mold flows from bottom to top in the rotor screw casting mold. The molten iron flows balanced, which greatly reduces the generation of iron beans, gas entrapment to form air holes, slag inclusions and other casting defects during the pouring process, while ensuring the axial dynamic balance performance of the rotor screw; 4) This application has fewer production links and simple production process control, and is easy to realize mechanized and batch production of large rotor screw castings; 5) Combined with the rapid heat transfer effect of the iron mold, the cooling speed of the mold is greatly improved, and high-strength performance of the cast state of large rotor screw castings can be achieved, and the energy-saving effect of the production process is significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the three-dimensional structure of the rotor screw casting according to an embodiment of the present utility model.

[0017] Figure 2 It is a schematic diagram of the main structure of the rotor screw casting of the embodiment of the present utility model.

[0018] Figure 3 It is a schematic top view of the structure of the rotor screw casting according to an embodiment of the present utility model.

[0019] Figure 4 It is a schematic diagram of the main structure of the casting mold box for casting a large rotor screw casting according to an embodiment of the present invention.

[0020] Figure 5 It is a schematic top view of the structure of the casting mold assembly for casting a large rotor screw casting according to an embodiment of the present invention.

[0021] Figure 6 The utility model is a side view of the structure of a casting mold assembly for casting a large rotor screw casting in an embodiment.

[0022] Figure 7 This is a schematic diagram of the pouring system structure of the screw casting in the embodiment of the utility model. Figure 1 .

[0023] Figure 8 This is a schematic diagram of the pouring system structure of the screw casting in the embodiment of the utility model. Figure 2 .

[0024] Figure 9 This is a schematic diagram of the pouring system structure of the screw casting in the embodiment of the utility model. Figure 3 .

[0025] Figure 10 It is a schematic diagram of molten iron filtration when the screw casting of the embodiment of the utility model is poured into a horizontal vertical casting mold.

[0026] Figure 11 It is a schematic diagram of the spiral tooth surface shell structure used for casting the rotor screw casting in an embodiment of the present utility model.

[0027] Figure 12 This is a schematic diagram of the upper and lower iron molds after horizontal sand coating molding in the production process of the rotor screw casting of the embodiment of the utility model.

[0028] Figure 13 This is a schematic diagram of placing a shell mold and a filter screen in a horizontally placed lower iron mold during the production process of a rotor screw casting according to an embodiment of the present invention.

[0029] Figure 14 This is a schematic diagram of the upper and lower iron molds after being horizontally closed and locked during the production process of the rotor screw casting of an embodiment of the utility model.

[0030] Figure 15 This is a schematic diagram of a casting mold flipped 90 degrees and erected during the production process of the rotor screw casting according to an embodiment of the present invention.

[0031] Figure 16 This is a schematic diagram of the filling process of molten iron in a vertical casting mold during the production process of the rotor screw casting of the embodiment of the present invention. Figure 1 .

[0032] Figure 17 This is a schematic diagram of the filling process of molten iron in a vertical casting mold during the production process of the rotor screw casting of the embodiment of the present invention. Figure 2 .

[0033] Figure 18 This is a schematic diagram of the filling process of molten iron in a vertical casting mold during the production process of the rotor screw casting of the embodiment of the present invention. Figure 3 .

[0034] Figure 19It is a schematic diagram of molten iron solidifying in a vertical casting mold during the production process of the rotor screw casting in an embodiment of the present invention.

[0035] Figure 20 This is a schematic diagram of loosening the locking device and opening the upper iron mold during the production process of the rotor screw casting according to an embodiment of the present invention.

[0036] Figure 21 This is a schematic diagram of removing the screw casting from the lower iron mold during the production process of the rotor screw casting in an embodiment of the present invention.

[0037] In the figure: rotor screw casting L: screw spiral tooth surface L1, upper support shaft L2, lower support shaft L3;

[0038] Upper iron mold 1, lower iron mold 2, spiral tooth shell mold 3, ceramic filter 4, lock box screw 5, pouring system 6, pouring cup 61, sprue 62, runner 63, ingode 64, gas riser 65, riser runner 66, gas outlet needle 67, upper runner 631, lower runner 632; molten iron flows to F. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and through examples. The following examples are provided to explain the present invention, but the present invention is not limited to the following examples.

[0040] Example

[0041] See also Figures 1 to 21 The device for casting a large screw compressor rotor screw casting in this embodiment includes a molten iron filtering device, a lock box screw 5 for locking and fixing the upper iron mold 1 and the lower iron mold 2, an upper support shaft L2 for forming the rotor screw casting L, a lower support shaft L3 casting cavity, a rotor screw spiral tooth surface shell mold 3 backing cavity, an iron mold sand-coated casting cavity for the entire casting system 6 cavity, and a coated sand shell mold cavity for forming the complete screw spiral tooth surface L1 casting cavity of the rotor screw casting L.

[0042] In this embodiment, the L casting mold of the large rotor screw casting adopts one mold and two parts, and the arrangement of the casting mold cavity in the upper and lower iron molds is axially horizontal, that is: one semicircular cavity in the rotor screw mold cavity of the two screws is set in the lower mold of the iron mold casting, and the other semicircular cavity is set in the upper mold of the iron mold casting. The upper and lower iron molds are respectively completed with sand-covered molding, and the screw spiral tooth surface shell mold is placed on the lower iron mold sand-covered casting. Then, the upper iron mold sand-covered casting is assembled onto the iron mold sand-covered casting of the lower iron mold to form a complete large rotor screw casting.

[0043] The mold cavity structure of this embodiment is a composite mold cavity, which mainly consists of two parts, namely: an iron mold covered sand mold cavity and a coated sand shell mold cavity. Among them, the iron mold covered sand mold cavity mainly forms the rotor screw support shaft mold cavity at both ends, the rotor screw spiral tooth surface shell backing cavity, and the entire casting system cavity; the coated sand screw spiral surface shell cavity mainly forms the rotor screw complete rotor spiral tooth surface mold cavity (see Figure 11 ), there is no parting surface on the spiral surface cavity of the rotor screw of this shell type, and there is no mold draft. It is a single spiral surface complete cavity, which can greatly reduce the processing workload of the spiral surface.

[0044] In this embodiment, two ceramic filter screens 4 are provided in the molten iron filtering device. The two ceramic filter screens 4 are both horizontally arranged in the sand-covered molding cavity in the lower iron mold 2 .

[0045] See also Figure 7-Figure 9 In this embodiment, the pouring system 6 includes a connected pouring cup 61, a straight runner 62, a cross runner 63, an inner runner 64, a gas outlet riser 65, a riser runner 66 and a gas outlet needle 67. The cross runner 63 is connected to the straight runner 62, and the cross runner 63 includes an upper cross runner 631 and a lower cross runner 632.

[0046] The entire pouring system 6 is made directly in the upper iron mold 1 and the lower iron mold 2. The arrangement of the pouring cup 61 and the sprue 62 cavity in the pouring system 6 in the upper iron mold 1 and the lower iron mold 2 is the same as the arrangement of the rotor screw casting L mold cavity, that is, one semicircular cavity of the sprue 62 is arranged in the upper iron mold 1, and the other semicircular cavity is arranged in the lower iron mold 2.

[0047] According to the structural characteristics, process requirements, and performance requirements of the rotor screw casting, the pouring system 6 of this embodiment adopts the form of bottom pouring. During pouring, the rotor screw casting is flipped 90°, and the axial arrangement of the rotor screw casting L casting cavity is changed from horizontal to vertical. The molten iron enters from the bottom surface of the lower support shaft L3 at the lower end of the rotor screw casting L casting cavity, and flows from bottom to top along the axial direction of the rotor screw casting L casting cavity to fill the mold.

[0048] In this embodiment, the runner 62 for filling the mold with unfiltered molten iron begins to occupy half of the upper iron mold 1 and the lower iron mold 2 respectively, and then gradually transitions upward to the cavity of the upper iron mold 1; the mold cavity for placing the ceramic filter screen 4 is bounded by the parting surface, and is entirely set in the lower iron mold 2. The lower runner 632 below the ceramic filter screen 4 is set in the lower iron mold 2, and then gradually transitions upward to the upper iron mold 1 until the cavities of the upper iron mold 1 and the lower iron mold 2 each occupy half.

[0049] In this embodiment, the cross-sectional shape of the inner runner 64 is circular, and the upper iron mold 1 and the lower iron mold 2 each occupy a semicircle; the air outlet riser 65 and the air outlet needle 67 are both circular; the riser diameter is determined according to the size of the rotor screw casting, and the air outlet needle diameter is also controlled within 15-20 mm according to the size of the rotor screw casting; the cross-sectional shape of the riser runner 66 is rectangular, and the upper iron mold 1 and the lower iron mold 2 cavity each occupy half.

[0050] In this embodiment, the overheated gas outlet riser 65 plays a good role in compensating the shrinkage of the molten iron in the rotor screw casting cavity; the gas outlet riser 65 also plays a role in floating the slag in the molten iron in the rotor screw casting cavity.

[0051] The ceramic filter screen 4 in the molten iron filtering device of this embodiment is arranged horizontally in the sand-covered mold cavity of the lower iron mold 2. When the iron mold needs to be poured, the iron mold needs to be turned 90 degrees, that is, the mold cavity of the original large screw casting that was horizontally axially arranged is turned into a vertical arrangement. At this time, the ceramic filter screen 4 that was originally arranged horizontally also becomes a vertical arrangement. This vertical ceramic filter screen 4 molten iron filtering method during molten iron pouring is completely different from the horizontal arrangement of the traditional ceramic filter screen. Figure 10 It can be seen in the figure that: when the molten iron enters the sprue 62 from top to bottom through the pouring cup 61, and after entering the bottom of the sprue 62, it separates into the left and right upper cross runners 631 cavities in the upper iron mold 1 respectively, the molten iron flows horizontally through the vertically arranged ceramic filter 4 to filter the molten iron, and then flows from the lower cross runner 632 cavity in the lower iron mold to fill the mold to the ingrown runner 64, and the molten iron fills upward through the ingrown runner 64 into the mold cavity of the rotor screw casting L.

[0052] The working process of the device for casting large screw compressor rotor screw castings in this embodiment is as follows: first, the upper iron mold 1 and the lower iron mold 2 of the large rotor screw are molded, and the rotor screw spiral tooth surface shell mold 3 cavity is molded; the two rotor screw spiral tooth surface shell mold 3 cavities are horizontally and axially placed one by one in the two corresponding iron mold sand casting backing cavities in the lower iron mold 2 of the large rotor screw; at the same time, two ceramic filter screens 4 are horizontally placed on the corresponding cavity positions of the molten iron filter device in the lower iron mold 2; then the upper iron mold (1) of the rotor screw is assembled onto the lower iron mold 2, and then the locking screw 5 is tightened to form a complete large rotor screw composite casting;

[0053] The entire iron mold is turned over 90 degrees, so that the rotor screw mold cavity and the pouring system 6 are turned over from the original axial horizontal arrangement to the axial vertical arrangement, and the molten iron inlet of the pouring cup 61 above the straight runner 62 is facing upward, and then the molten iron can be poured; the poured molten iron enters the cross runner 63 through the pouring cup 61 and the straight runner 62, and the molten iron is filtered by the vertically arranged ceramic filter 4 device to block the slag; the filtered molten iron passes through the cross runner 63 at the other end of the ceramic filter 4, continues to fill the mold and flows to the inner gate set at the bottom plane of the rotor screw support shaft, and enters the mold cavity of the rotor screw upward, and the molten iron continuously fills the rotor screw mold cavity from bottom to top, and the filling flow is smooth until the entire rotor screw mold cavity is completely filled; the gas generated in the mold cavity during the filling process is discharged in time through the outlet needle 67 on the outlet riser 65 at the top of the rotor screw to the atmosphere; then the cooler molten iron in the upper part of the rotor screw cavity and the floating slag-containing molten iron continue to fill the mold upward and enter the gas outlet riser 65 above the rotor screw casting cavity. When the filling height of this type of molten iron in the gas outlet riser 65 reaches the height of the lower edge of the riser runner 66 above the sprue 62, the molten iron in the rotor screw cavity no longer fills the mold upward, and the high-temperature molten iron directly fills the gas outlet riser 65 through the riser runner 66. In this way, the temperature of the molten iron in the gas outlet riser 65 is higher than the temperature of the molten iron above the rotor screw. The molten iron in the gas outlet riser 65 can well compensate for the shrinkage of the molten iron above the rotor screw. At the same time, the slag inclusions in the molten iron in the casting cavity of the rotor screw casting L can enter the gas outlet riser 65 by floating before solidification. Subsequently, the molten iron in the casting cavity begins to solidify and cool, thereby finally obtaining a high-quality rotor screw casting L without shrinkage cavities, shrinkage porosity, and slag inclusion defects;

[0054] After the molten iron in the mold has solidified and cooled, the upper and lower molds are turned 90 degrees, so that the parting surface of the upper and lower molds is reversed from the vertical arrangement to the horizontal arrangement when the molds are originally closed. Then the locking screws are loosened, the upper and lower molds are opened and separated, and the casting is taken out (the casting is in the shape of a semicircular shaft in both the upper and lower molds, and the casting and the mold are easily separated). This completes the casting production of a large rotor screw casting, and ultimately obtains a large rotor screw casting with dense structure and fine grains, realizing the as-cast casting production of large rotor screw castings. This cycle can be repeated to achieve mass production of such castings.

[0055] The process principle of the composite casting device of this embodiment is as follows: To ensure the axial dynamic balance of the rotor screw casting, the rotor screw casting L must be arranged vertically within the mold during the casting process. For large rotor screw castings, the rotor screw casting L is arranged vertically axially, and the height of the casting cavity within the mold exceeds 1000 mm. For such a high mold height, the molten iron pouring process must adopt a bottom pouring method. This molten iron pouring process ensures that the molten iron poured into the mold is smoothly filled from bottom to top, while also allowing inclusions in the molten iron to float away, thereby producing a defect-free, high-quality casting. For large rotor screw castings, each casting typically weighs 400-600 kg, is approximately 1000 mm long, and has a maximum diameter of the screw helical tooth surface of approximately 350-450 mm. If this type of casting is arranged perpendicular to the iron mold parting surface in the iron mold sand-coated casting, the thickness of the single iron mold will exceed 600 mm, and it will be small at both ends and large in the middle, which will cause great difficulty in the sand-coated molding of the iron mold sand-coated casting, or require a sand-coated molding machine with a larger stroke and demolding force; in addition, it is difficult to achieve a completely bottom-pouring pouring method in a large rotor screw using this arrangement; at the same time, when this arrangement is used for the production of large rotor screw castings, after the large rotor screw casting is solidified and cooled, the separation between the casting and the iron mold will be difficult due to the cooling and shrinkage of the casting, etc. The large rotor screw casting mold of the present application adopts a one-type two-piece large rotor screw casting mold, and the large rotor screw casting cavity is arranged axially and horizontally in the iron mold casting; the straight runner 62, the cross runner 63, the inner runner 64, the molten iron filter flow channel, etc. of the pouring system 6 are all made on the iron mold sand-coated casting at the parting surface of the upper and lower iron molds ( Figure 7-Figure 9 ); Place the rotor screw helical tooth shell 3 axially and horizontally in the lower iron mold sand casting cavity, place the molten iron ceramic filter 4 horizontally in the lower iron mold sand casting, close the box horizontally, and then lock the upper and lower molds ( Figure 4-Figure 6 ); then the mold after closing and locking is flipped vertically by 90°, so that the rotor screw mold cavity, which was originally arranged horizontally in the axial direction, is flipped to be arranged vertically in the axial direction. Pouring the mold in this state can realize the bottom injection filling mode of molten iron in the large rotor screw casting mold, so that the large rotor screw casting mold is filled, solidified and cooled under a relatively ideal state, and finally realize the high-quality casting production of large screw castings. During the cooling process, the molten iron in the large rotor screw mold cavity of this embodiment can make full use of the expansion caused by the graphite precipitated during the solidification process of the molten iron to offset the liquid contraction caused by the cooling of the molten iron. At the same time, the strong shrinkage compensation effect of the high-temperature molten iron in the air outlet riser 65 above the screw casting cavity makes the molten iron utilization rate of this embodiment much higher than that of traditional sand casting.

[0056] This embodiment addresses the casting process requirements for axial vertical bottom pouring of large screw compressor rotor screw castings L and the forming process characteristics of iron mold sand-coated castings. In a single-open iron mold sand-coated casting with upper and lower horizontal parting, a casting mold with a half of the iron mold sand-coated arranged along the axial direction of the rotor screw is horizontally produced in each of the upper and lower iron mold cavities, along with a corresponding pouring system 6. After the upper and lower mold halves are horizontally combined with the screw helical tooth surface shell mold 3, a complete horizontally arranged large rotor screw casting cavity and its corresponding pouring system 6 are formed. By flipping the parting surface of the large rotor screw casting L by 90° from the horizontal position after the combined box is locked, the sprue in the casting system is vertically upward and the parting surface of the casting is perpendicular to the horizontal plane. In this way, the casting cavity of the rotor screw in the entire composite casting can be arranged vertically. In this state, molten iron is poured in, and the molten iron smoothly enters the casting cavity of the rotor screw casting through the bottom of the lower support shaft of the rotor screw casting cavity, such as the pouring cup 61, the straight runner 62, the cross runner filter device, and the inner runner 64, from bottom to top until the entire rotor screw casting cavity is filled. The molten iron is poured and filled smoothly. By utilizing the characteristics of good rigidity and fast cooling speed of the iron mold sand-coated casting, by reasonably setting the cross-sectional dimensions of the pouring system, small riser casting of large rotor screw castings can be achieved, and the casting has fine grains, dense internal structure, excellent comprehensive mechanical properties and good dynamic balance performance. At the same time, casting defects such as iron bean splashing, air entanglement, slag inclusion, shrinkage and shrinkage holes in the rotor screw casting during the molten iron pouring process are avoided.

[0057] Through the above description, those skilled in the art can already implement it.

[0058] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is merely an example of the structure of the utility model. Any equivalent changes or simple changes made based on the structure, features and principles described in the concept of this utility model patent are included in the protection scope of this utility model patent. Technicians in the technical field of the utility model can make various modifications or supplements to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the utility model or exceed the scope defined by the claims, they should fall within the protection scope of the utility model.

Claims

1. A device for casting a large screw compressor rotor screw casting, comprising a lock box screw (5) for locking and fixing an upper iron mold (1) and a lower iron mold (2), characterized in that: The invention also includes an upper support shaft (L2) and a lower support shaft (L3) casting cavity for forming a rotor screw casting (L), a rotor screw spiral tooth surface shell mold (3) backing cavity, an iron mold sand casting cavity for a casting system (6) cavity, and a coated sand shell mold cavity for forming a screw spiral tooth surface (L1) casting cavity for a rotor screw casting (L), wherein the casting system (6) is arranged in the upper iron mold (1) and the lower iron mold (2), and the casting system (6) The arrangement adopts the form of bottom pouring, and the pouring system (6) includes a connected pouring cup (61) and a sprue (62), and the arrangement of the pouring cup (61) and the sprue (62) cavity in the upper iron mold (1) and the lower iron mold (2) is axially horizontal; the arrangement of the pouring cup (61) and the sprue (62) cavity in the upper iron mold (1) and the lower iron mold (2) and the arrangement of the rotor screw casting (L) cavity are both axially horizontal.

2. The device for casting a large screw compressor rotor screw casting according to claim 1, characterized in that: The rotor screw casting (L) is a two-piece casting in an iron mold, and half of the cavity of the circular rotor screw casting (L) is arranged in the upper iron mold and the other half is arranged in the lower iron mold.

3. The device for casting a large screw compressor rotor screw casting according to claim 1, characterized in that: It also includes a ceramic filter screen (4), which is horizontally arranged in the sand-covered molding cavity in the lower iron mold (2).

4. The device for casting a large screw compressor rotor screw casting according to claim 1, characterized in that: The pouring system (6) further comprises a horizontal runner (63), which is connected to the sprue (62), wherein a semicircular cavity of the sprue (62) is arranged in the upper iron mold (1), and another semicircular cavity of the sprue (62) is arranged in the lower iron mold (2).

5. The device for casting a large screw compressor rotor screw casting according to claim 1 or 4, characterized in that: The pouring system (6) further comprises an inner runner (64), an air outlet riser (65), a riser runner (66) and an air outlet needle (67). The cross-sectional shape of the inner runner (64) is circular, with the upper iron mold (1) and the lower iron mold (2) each occupying a half of the circle; the air outlet riser (65) and the air outlet needle (67) are both circular; the cross-sectional shape of the riser runner (66) is rectangular, with the upper iron mold (1) and the lower iron mold (2) each occupying a half of the cavity.

6. The device for casting a large screw compressor rotor screw casting according to claim 5, characterized in that: The diameter of the gas outlet riser (65) is determined according to the size of the rotor screw casting (L), and the diameter of the gas outlet needle (67) is controlled to be between 15 and 20 mm according to the size of the rotor screw casting (L).

7. The device for casting a large screw compressor rotor screw casting according to claim 1, characterized in that: The pouring cup (61) is a conical pouring cup (61) which is directly made in the upper iron mold (1) and the lower iron mold (2). The upper iron mold (1) and the lower iron mold (2) each occupy half of the cavity, with the iron mold parting surface as the boundary.

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