CN219034671U - A two-stage forging and milling tool for downhole casing - Google Patents

Abstract

The utility model discloses a two-stage forging and milling tool for downhole casing, which comprises a casing, a mandrel, a transmission piston, a middle forging and milling structure and a lower forging and milling structure. The middle forging and milling structure and the lower forging and milling structure are installed on the sipes of the shell, the middle forging and milling structure is set above the lower forging and milling structure, the upper end of the mandrel is connected with the transmission piston, the mandrel and the transmission piston Both are embedded in the inner cavity of the housing; the mandrel abuts against the middle forging and milling structure and the lower forging and milling structure arranged in the sipes of the housing by sliding inside the housing. The utility model solves the technical problems of fast tool wear, poor forging and milling efficiency and short single-pass footage in the prior art through the two-stage forging and milling tool for the downhole casing.

Description

A two-stage forging and milling tool for downhole casing

technical field

The utility model relates to the field of forging and milling of oil and gas well workover casings, in particular to a two-stage forging and milling tool for downhole casings.

Background technique

With the continuous deepening of oilfield development, some oil wells will face scrapping and abandonment in the later stage. For the sake of economy and protection of the ecological environment, it is usually necessary to permanently scrap some wells or plug some well sections. According to the technical requirements for plugging abandoned wells, plugging wells needs to inject cement plugs in the open hole section, cement plugs in the cut position of the casing, and cement plugs in the perforated section of the injection-production layer. Some oil wells with poor cementing quality or deformed or damaged casing in the wellbore need to be run into forging and milling tools to cut and mill the deformed or severely damaged casing, and then inject cement plugs or bridge plugs at appropriate positions in the well Securely block. In addition, when sidetracking construction is required, it is also necessary to lower a forging and milling tool to cut and mill a certain length of casing in the wellbore to provide a new channel for the next step of sidetracking.

At present, traditional forging and milling tools have the disadvantages of fast tool wear, slow forging and milling speed, long casing forging and milling time, and short footage per pass. After the traditional forging and milling tool is lowered to the design depth, the pump is turned on to circulate and the pressure is gradually increased. During the process of increasing the pressure, the blade of the tool is opened, and the side edge of the blade first contacts the inner wall of the casing. Through rotating cutting and slowly pressurizing, the casing wall Keep thinning until the casing is milled, and then start to lower the drilling tool for pressurized milling. During pressurized milling, the bottom edge of the blade cuts the casing. With the continuous lowering of the drilling tool, until the forging and milling length required by the design is reached . According to the application situation on site, the operation of forging and milling is complex, the construction volume is large, and the construction cost is high. Moreover, the smaller the borehole size, the more difficult it is for forging and milling.

Utility model content

The purpose of the utility model is to provide a two-stage forging and milling tool for downhole casing, so as to solve the technical problems of fast tool wear, poor forging and milling efficiency and short footage in a single pass in the prior art.

In order to achieve the above purpose, the utility model provides a two-stage forging and milling tool for downhole casing, which includes a casing, a mandrel, a transmission piston, a middle forging and milling structure and a lower forging and milling structure, and is characterized in that the casing There are multiple sipes on the side wall, and the middle forging and milling structure and the lower forging and milling structure are installed on the sipes of the shell. The middle forging and milling structure is set above the lower forging and milling structure. The upper end of the mandrel is connected with the transmission piston. Both the mandrel and the transmission piston are embedded in the inner cavity of the housing; the mandrel slides inside the housing and abuts against the middle forging and milling structure and the lower forging and milling structure arranged in the sipes of the housing.

Further, the upper part of the casing is provided with a piston guide groove, which is connected to the upper joint through threads, and the knife groove opened on the casing is a stepped through-hole structure, and the large-diameter end of the stepped through-hole is outside the casing. One side, the small-diameter end is on the inner side of the shell, and the connection between the large-diameter end and the small-diameter end of the sipes forms a stepped surface; the plurality of sipes are respectively the middle sipes, the lower short sipes and the lower long sipes. The two middle sipes are evenly distributed in the middle section of the side wall of the housing, and the plurality of short lower sipes and lower long sipes are uniformly distributed across the lower section of the side wall of the housing, and the length of the lower short sipes is shorter than that of the lower long knife The length of the groove, the vertical lower ends of the lower short sipe and the lower long sipe are located on the same horizontal plane.

Further, the transmission piston is arranged in the piston guide groove, a sealing ring is arranged on the side wall of the transmission piston and the piston guide groove, the transmission piston is provided with a diverter plate and a nozzle, and the transmission piston and the mandrel are arranged on the upper end of the mandrel .

Further, the outer contours of the middle section and the lower section of the mandrel are processed into ring-shaped middle toothed cylinders and lower cylinders. The middle toothed cylinders are provided with ring-shaped racks, and the lower circles Perforations are evenly opened on the side of the barrel; a spring is set on the upper end of the mandrel, and the spring is installed in the piston guide groove. catch.

Further, the middle forging and milling structure is composed of a middle forging and milling cutter and a middle tool holder, the middle tool holder is connected with the stepped surface of the middle sip groove by bolts, and the middle forging and milling cutter is hinged with the middle tool holder through a positioning shaft.

Further, the back of the middle forging and milling cutter is provided with an incomplete gear and a first curved edge, and the incomplete gear can mesh with the rack provided on the middle toothed cylinder.

Further, the lower forging and milling structure is composed of a lower short forging and milling structure and a lower long forging and milling structure, the lower short forging and milling structure is composed of a lower short forging and milling cutter and a lower short tool holder, and the lower short tool holder is connected to the stepped surface of the lower short tool groove by bolts , the lower short forging and milling cutter is hinged with the lower short tool holder through the positioning shaft; the lower long forging and milling structure is composed of the lower long forging and milling cutter and the lower long tool holder, and the lower long forging and milling cutter is connected with the stepped surface of the lower long tool groove through bolts, The lower long forging and milling cutter is hinged with the lower long tool holder through the positioning shaft; the length of the lower short forging and milling cutter is less than the length of the lower long forging and milling cutter.

Further, the back of the lower short forging and milling cutter is provided with a second curved edge, and the back of the lower long forging and milling cutter is provided with a third curved edge.

Further, the blade face of the middle forging and milling cutter is provided with first-type cutting teeth and second-type cutting teeth, and the upper end of the middle forging and milling cutter is provided with a positioning hole, and the positioning hole is hinged with the positioning shaft arranged on the middle tool rest, The central forging and milling cutter rotates in the cutter groove on the shell around the positioning shaft.

Further, the blade surfaces of the lower short forging milling cutter and the lower long forging milling cutter are provided with first-type cutting teeth and second-type cutting teeth, and the upper ends of the lower short forging milling cutter and the lower long forging milling cutter are provided with positioning holes, The positioning hole is hinged with the positioning shaft arranged on the lower short tool rest and the lower long tool rest, and the lower short forging and milling cutter and the lower long forging and milling cutter rotate in the cutter groove on the housing around the positioning shaft.

Based on the above technical solution, the utility model can produce the following beneficial effects:

(1) Strong adaptability. According to different construction conditions, one-piece tool holder and cutting tool can be prepared in advance according to the mastered information. At the same time, it is easy to disassemble and assemble the cutting tool, which can meet different forging and milling needs.

(2) Good stability. All forging and milling cutters in the forging and milling machine are connected with the corresponding one-piece tool holder to ensure that the initial state of the forging and milling machine is stable when it is lowered into the well. The lower part of the forging and milling machine uses the boss on the mandrel to push the tool The outer sheet can work, the middle part uses the principle of rack and pinion to drive the outer sheet of the forging and milling cutter to work, and the two-stage forging and milling machine works independently.

(3) High forging and milling efficiency. Two types of tungsten carbide cutter teeth are designed for the cutting and forging and milling states of the casing, which enhances the eating ability of the cutter plate. The cutter teeth adopt concave teeth, which is conducive to cutting the formed iron wire , Prevent iron filings from winding, improve cutting efficiency and forging and milling efficiency.

(4) Good economy. The utility model is equipped with two-stage forging and milling tools, which has a simple structure, reduces the number of times of drilling during forging and milling operations, prolongs the length of forging and milling for one drilling, saves forging and milling time, and reduces operating costs.

Description of drawings

Fig. 1 is the structural representation of the utility model embodiment;

Fig. 2 is the external structure schematic diagram of the utility model embodiment;

Fig. 3 is a schematic structural view of the forging and milling cutter in the middle part of the utility model embodiment;

Fig. 4 is a schematic structural view of the lower short forging and milling cutter of the utility model embodiment;

Fig. 5 is a schematic structural view of the lower long forging and milling cutter of the utility model embodiment;

In the figure: 1, shell; 1-1, middle sipe; 1-2, lower end sipe; 1-3, lower long sipe; 1-4, piston guide groove; 2, mandrel; 2-1 , middle toothed cylinder; 2-2, lower cylinder; 3, transmission piston; 3-1, sealing ring; 3-2, diverter plate; 3-3, nozzle; 4, middle forging and milling cutter; 4-1 , incomplete gear; 4-2, the first knife back curved edge; 5, the middle tool holder; 6, the lower short forging and milling cutter; 6-1, the second knife back curved edge; 7, the lower short tool holder; 8, the lower long forging Milling cutter; 8-1, the third knife back curved edge; 9, the lower long tool holder; 10, spring; 11, the upper joint; 12, positioning shaft; 13, the first type of cutting teeth; 14, the second type of cutting teeth; 15. Positioning hole.

Detailed ways

In order to better understand the purpose, structure and function of the utility model, a two-stage forging and milling tool for downhole casing of the utility model will be further described in detail below in conjunction with the accompanying drawings.

In the description of the present utility model, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the utility model and simplified descriptions, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.

As shown in Figure 1, the utility model is a two-stage forging and milling tool for downhole casing, which includes a housing 1, a mandrel 2, a transmission piston 3, a middle forging and milling structure and a lower forging and milling structure. The side wall of the body 1 is provided with a plurality of sipes, the middle forging and milling structure and the lower forging and milling structure are installed on the sipes of the housing 1, the middle forging and milling structure is arranged above the lower forging and milling structure, the upper end of the mandrel 2 Connected with the transmission piston 3, both the mandrel 2 and the transmission piston 3 are embedded in the inner cavity of the housing 1; the mandrel 2 slides inside the housing 1 with the middle forging and milling structure set in the sipes of the housing 1 and The lower forging and milling structure abuts.

As shown in Figure 2, the upper section of the housing 1 is provided with a piston guide groove 1-4, and the piston guide groove 1-4 is connected to the upper joint 11 through threads, and the knife groove provided on the housing 1 is a stepped through-hole structure. The large-diameter end of the stepped through hole is on the outer side of the housing 1, and the small-diameter end is on the inner side of the housing 1, and the connection between the large-diameter end and the small-diameter end of the sipes forms a stepped surface; the plurality of sipes are respectively The middle sipe 1-1, the lower short sipe 1-2 and the lower long sipe 1-3, a plurality of the middle sipe 1-1 are evenly distributed in the middle section of the side wall of the housing 1, and a plurality of the lower short sipe The slots 1-2 and the lower long sipes 1-3 are uniformly distributed across the lower section of the side wall of the housing 1, the length of the lower short sipes 1-2 is less than the length of the lower long sipes 1-3, and the lower short sipes 1-2 It is located on the same horizontal plane as the vertical lower end of the lower long sipe 1-3.

Specifically, the inner diameter of the piston guide groove 1-4 is larger than the outer diameter of the mandrel 2, and six identical middle sipes 1-1 are evenly distributed on the housing 1 along the circumferential direction, and can accommodate the middle tool holder 5 and the middle forging and milling cutter 4 , three lower long sipes and three middle short sipes provided by the lower forging and milling part can respectively accommodate the lower short tool holder 7, the lower long tool holder 9, the lower short forging milling cutter 6 and the lower long forging milling cutter 8 matched therewith.

As shown in Figure 1, the transmission piston 3 is set in the piston guide groove 1-4, the side wall of the transmission piston 3 and the piston guide groove 1-4 is provided with a sealing ring 3-1, and the transmission piston 3 is provided with a diverter plate 3 -2 and nozzle 3-3, the transmission piston 3 and the mandrel 2 are arranged on the upper end of the mandrel 2.

Specifically, the splitter plate 3-2 is disc-shaped, with four evenly distributed through holes in the middle. Through the flow channel, the outer diameter of the piston 3 is equal to the inner diameter of the housing 1 and two sealing rings 3-1 are provided.

The mandrel 2 is all processed into the ring-shaped middle toothed cylinder 2-1 and the lower cylinder 2-2 in the outer contour of the middle section and the lower section matched with the housing 1, and the middle toothed cylinder 2-1 is provided with Ring-shaped rack, perforations 2-3 are evenly opened on the side of the lower cylinder 2-2; The top is in contact with the lower surface of the transmission piston 3, and the bottom of the spring 10 is in contact with the step surface of the piston guide groove 1-4, wherein the spring 10 can be compressed under the pressure of the piston 3, and can be restored after the pressure disappears;

Specifically, the six perforations 2-3 uniformly distributed along the circumferential direction opened on the lower cylinder 2-2 are facing the tooth surface of the first type cutting teeth 13 at the lower part.

As shown in Figure 3, the middle forging and milling structure is composed of the middle forging and milling cutter 4 and the middle tool holder 5, the middle tool holder 5 is connected with the stepped surface of the middle sip groove 1-1 through bolts, and the middle forging and milling cutter 4 passes through the positioning shaft 12 Hinged with middle knife rest 5.

The back of the middle forging and milling cutter 4 is provided with an incomplete gear 4-1 and a first curved edge 4-2, and the incomplete gear 4-1 can be connected with the rack provided on the middle toothed cylinder 2-1 engage.

Specifically, the length of all the screws of the middle forging and milling structure is less than the wall thickness of the shell 1 after all the screws are screwed in, and the six middle forging and milling cutters 4 on the same circumference are opened from the initial state to the full opening process, and the middle forging and milling cutters 4 are opened The angles are the same, the first cutting teeth 13 of the middle forging and milling cutter 4 are located on the same circumferential surface from the outer end surface to the outer end surface of the cutter plate, and the second cutting teeth 14 at the bottommost end of the cutter teeth are located on the same horizontal plane.

As shown in Figure 4-5, the lower forging and milling structure is composed of the lower short forging and milling structure and the lower long forging and milling structure. The lower short forging and milling structure is composed of the lower short forging and milling cutter 6 and the lower short tool holder 7, and the lower short tool holder 7 is passed through the bolt. It is connected with the step surface of the lower short tool groove 1-2, the lower short forging milling cutter 6 is hinged with the lower short tool rest 7 through the positioning shaft 12; the lower long forging and milling structure is composed of the lower long forging milling cutter 8 and the lower long tool rest 9, and the lower The long forging and milling cutter 8 is connected with the step surface of the lower long sipes 1-3 by bolts, and the lower long forging and milling cutter 8 is hinged with the lower long tool rest 9 through the positioning shaft 12; the length of the lower short forging and milling cutter 6 is less than the lower The length of the minister forging milling cutter 8.

The back of the short forging and milling cutter 6 of the bottom is provided with a second curved edge 6-1, and the back of the bottom long forging and milling cutter 8 is provided with a third curved edge 8-1.

Specifically, the lower forging and milling structure is used as the first forging and milling part. After all the screws on the lower forging and milling structure are screwed into the tool holder, the length is less than the wall thickness of the shell 1. The six forging and milling cutters on the same circumference are from the initial state to fully opened. During the process, the first type of cutting teeth 13 of the lower short forging and milling cutter 6 and the lower long forging and milling cutter 8 are located on the same circumferential surface from the outer end surface to the outer end surface of the cutter plate, and the second type of cutting teeth at the bottom of the cutter teeth The teeth 14 are located on the same horizontal plane. During the downward movement of the mandrel, the lower cylinder 2-2 at the bottom of the mandrel 2 pushes the second curved edge 6-1 and the third curved edge 8-1 on the handle. When presetting the force, the lower short forging and milling cutter 6 and the lower long forging and milling cutter 8 begin to stretch out around the positioning axis 12, and the maximum angle of opening is limited by the height of the boss and the tool holder.

The blade faces of the middle forging and milling cutter 4, the lower short forging and milling cutter 6 and the lower long forging and milling cutter 8 are all provided with first-type cutting teeth 13 and second-type cutting teeth 14, and the middle forging and milling cutter 4 and the lower short forging and milling cutter 6 and the upper end of the lower long forging and milling cutter 8 are provided with a positioning hole 15, and the positioning hole 15 is hinged with the positioning shaft 12 arranged on the middle tool rest 5, the lower short tool rest 7 and the lower long tool rest 9, and the middle forging and milling cutter 4. The lower short forging and milling cutter 6 and the lower long forging and milling cutter 8 rotate in the groove on the housing 1 around the positioning shaft 12 .

Specifically, the first type of cutting teeth 13 located on the outside are used to quickly cut off the casing during cutting, and the second type of cutting teeth 14 are used for normally downward forging and milling of the casing.

Specifically, the positioning holes 15 of all forging and milling cutters are arranged at the upper end of the knife handle, and the concave circular tooth abrasive grains are surfacing on the upper surface of the knife handle base plate by soldering. The concave circular tooth abrasive grains have a certain inner chamfer, which can Prevent forging and milling cutters from forming long iron filings when cutting casing, which is beneficial to cutting casing and drilling fluid to carry iron filings.

Specifically, the incomplete gear 4-1 of the middle forging and milling cutter 4 is welded on the inner side of the upper end of the knife handle, and the inner hole of the incomplete gear 4-1 and the positioning hole 15 of the forging and milling cutter are coaxially matched, so the middle forging and milling cutter 4 The structure is different from the lower short forging and milling cutter 6 and the lower long forging and milling cutter 8, but the middle forging and milling cutter 4 has the same working radius as the lower short forging and milling cutter 6 and the lower long forging and milling cutter 8.

Specifically, if the tool of the forging and milling machine needs to be replaced with a new tool after it is worn out, it is only necessary to disassemble the integrated tool holder and replace it with a new tool.

The concrete operation principle of the present utility model is:

The motor is connected to the upper joint 11 to drive the forging and milling tool to rotate at high speed. When there is pump pressure, the drilling fluid flows from the inlet to the diverter plate 3-2 of the upper cavity of the casing 1, and the diverter plate 3-2 diverts the drilling fluid. Above the drive piston 3, when a certain pump pressure is reached, the drilling fluid pushes the drive piston 3 to drive the mandrel 2 to slide downward in the cavity of the housing 1. At this time, the spring 10 sleeved on the mandrel 2 Compressed under the extrusion action of the lower surface of the transmission piston 3.

Pushed by the pressure, the piston 3 drives the mandrel 2 to go down, and first pushes the lower short forging and milling cutter 6 and the lower long forging and milling cutter 8 to expand outward, and the lower cylinder 2-2 of the mandrel 2 pushes the second knife back curve on the handle. When the edge 6-1 and the third curved edge 8-1 reach the preset force, the lower short forging and milling cutter 6 and the lower long forging and milling cutter 8 start to protrude around the positioning axis 12 and move towards the lower short tool groove of the housing 1 1-2 and external rotation of lower long sipe 1-3.

The first type cutting teeth 13 of the forging and milling cutter cut the casing wall. When the casing is gradually expanded to cut off the casing, the mandrel 2 continues to go down to the lower short forging and milling cutter 6 and the lower long forging and milling cutter 8 to the maximum. The location is limited. At this time, the drilling tool can be lowered to apply drilling pressure to carry out casing forging and milling construction. When the iron filings returned by the mud reflect that the lower forging mill loses the forging and milling ability, stop applying drilling pressure first, and increase the pressure of the mud pump to continue. The piston drives the mandrel to move down. At this time, the lower short forging and milling cutter 6 and the lower long forging and milling cutter 8 have passed the lower cylinder 2-2 of the mandrel 2, and no longer participate in the forging and milling work.

After the mandrel 2 goes down for a certain distance, the rack set on the middle toothed cylinder 2-1 meshes with the incomplete gear 4-1 set on the upper end of the middle forging and milling cutter 4, and the rack continues to run downward with the mandrel 2 , under the effect of the incomplete gear 4-1 meshing, the middle forging and milling cutter 4 rotates to the outside of the middle sipes 1-1 of the housing 1 around the positioning shaft 12 provided on the middle tool holder 5 .

When the forging and milling cutter 4 in the middle is gradually expanded to the maximum limit position, lower the drilling tool to apply drilling pressure to continue construction on the casing. After the construction is completed, lift the forging and milling tool to a certain distance. Drive the mandrel 2 to reset under the action of the spring 10, the incomplete gear 4-1 drives the middle forging and milling cutter 4 to rotate reversely around the positioning hole 15 through the rack and pinion engagement, and gradually restores the contraction state, the lower forging and milling cutter 6 and the lower long The forging and milling cutter 8 is retracted in the cutter groove by the self-generated weight and the pressure difference in the casing 1 after the mud pump is stopped, and then the rotary table is closed to carry out the tripping operation.

It can be understood that the utility model is described through some embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the utility model . In addition, the features and embodiments may be modified to adapt a particular situation and material to the teachings of the invention without departing from the spirit and scope of the invention. Therefore, the utility model is not limited by the specific embodiments disclosed here, and all embodiments falling within the scope of the claims of the application belong to the protection scope of the utility model.

Claims (10)

1. The two-stage forging and milling tool for the underground sleeve comprises a shell (1), a mandrel (2), a transmission piston (3), a middle forging and milling structure and a lower forging and milling structure, and is characterized in that a plurality of cutter grooves are formed in the side wall of the shell (1), the middle forging and milling structure and the lower forging and milling structure are arranged on the cutter grooves of the shell (1), the middle forging and milling structure is arranged above the lower forging and milling structure, the upper end of the mandrel (2) is connected with the transmission piston (3), and the mandrel (2) and the transmission piston (3) are embedded into an inner cavity of the shell (1); the mandrel (2) is in butt joint with a middle forging and milling structure and a lower forging and milling structure which are arranged in a cutter groove of the shell (1) through sliding in the shell (1).

2. The two-stage forging and milling tool for the underground sleeve according to claim 1 is characterized in that a piston guide groove (1-4) is formed in the upper section of the shell (1), the piston guide groove (1-4) is connected with an upper joint (11) through threads, a cutter groove formed in the shell (1) is of a stepped through hole structure, the large-diameter end of the stepped through hole is arranged on the outer side of the shell (1), the small-diameter end of the stepped through hole is arranged on the inner side of the shell (1), and a step surface is formed at the joint of the large-diameter end and the small-diameter end of the cutter groove; the cutter grooves are respectively a middle cutter groove (1-1), a lower short cutter groove (1-2) and a lower long cutter groove (1-3), the middle cutter grooves (1-1) are uniformly distributed on the middle section of the side wall of the shell (1), the lower short cutter grooves (1-2) and the lower long cutter grooves (1-3) are uniformly and crosswise distributed on the lower section of the side wall of the shell (1), the length of the lower short cutter groove (1-2) is smaller than that of the lower long cutter groove (1-3), and the vertical lower ends of the lower short cutter groove (1-2) and the lower long cutter groove (1-3) are located on the same horizontal plane.

3. The two-stage forging and milling tool for the underground sleeve according to claim 1, wherein the transmission piston (3) is arranged in the piston guide groove (1-4), a sealing ring (3-1) is arranged on the side wall of the transmission piston (3) matched with the piston guide groove (1-4), the transmission piston (3) is provided with a flow distribution disc (3-2) and a nozzle (3-3), and the transmission piston (3) and the mandrel (2) are arranged at the upper end of the mandrel (2).

4. The two-stage forging and milling tool for the underground casing according to claim 1, wherein the mandrel (2) is provided with an annular middle toothed cylinder (2-1) and an annular lower cylinder (2-2) on the outer contours of the middle section and the lower section matched with the shell (1), the middle toothed cylinder (2-1) is provided with annular racks, and the side edges of the lower cylinder (2-2) are uniformly provided with perforations (2-3); the upper end of the mandrel (2) is sleeved with a spring (10), the spring (10) is installed in the piston guide groove (1-4), the top of the spring (10) is abutted with the lower surface of the transmission piston (3), and the bottom of the spring (10) is abutted with the step surface of the piston guide groove (1-4).

5. A downhole casing two-stage forging and milling tool according to claim 1, wherein the middle forging and milling structure is composed of a middle forging and milling cutter (4) and a middle cutter holder (5), the middle cutter holder (5) is connected with the step surface of the middle cutter slot (1-1) through bolts, and the middle forging and milling cutter (4) is hinged with the middle cutter holder (5) through a positioning shaft (12).

6. The two-stage forging and milling tool for the underground sleeve, as set forth in claim 5, wherein the incomplete gear (4-1) and the first back curved edge (4-2) are provided on the back of the middle forging and milling tool (4), and the incomplete gear (4-1) can be meshed with a rack provided on the middle toothed cylinder (2-1).

7. A downhole casing two-stage forging and milling tool according to claim 1, wherein the lower forging and milling structure consists of a lower short forging and milling structure and a lower long forging and milling structure, the lower short forging and milling structure consists of a lower short forging and milling cutter (6) and a lower short cutter holder (7), the lower short cutter holder (7) is connected with the step surface of the lower short cutter groove (1-2) through a bolt, and the lower short forging and milling cutter (6) is hinged with the lower short cutter holder (7) through a positioning shaft (12); the lower long forging milling structure is composed of a lower long forging milling cutter (8) and a lower long cutter rest (9), the lower long forging milling cutter (8) is connected with the step surface of the lower long cutter groove (1-3) through bolts, and the lower long forging milling cutter (8) is hinged with the lower long cutter rest (9) through a positioning shaft (12); the length of the lower short forging milling cutter (6) is smaller than the length of the lower long forging milling cutter (8).

8. The two-stage forging and milling tool for the underground sleeve according to claim 7, wherein the tool back surface of the lower short forging milling cutter (6) is provided with a second tool back curved edge (6-1), and the tool back surface of the lower long forging milling cutter (8) is provided with a third tool back curved edge (8-1).

9. The two-stage forging and milling tool for the underground sleeve according to claim 5, wherein the cutter blade surfaces of the middle forging and milling cutter (4) are provided with first-type cutting teeth (13) and second-type cutting teeth (14), the upper end of the middle forging and milling cutter (4) is provided with a positioning hole (15), the positioning hole (15) is hinged with a positioning shaft (12) arranged on a middle cutter rest (5), and the middle forging and milling cutter (4) rotates around the positioning shaft (12) in a cutter groove on the shell (1).

10. The two-stage forging and milling tool for the underground sleeve according to claim 7, wherein the cutting edge surfaces of the lower short forging milling cutter (6) and the lower long forging milling cutter (8) are provided with first type cutting teeth (13) and second type cutting teeth (14), the upper ends of the lower short forging milling cutter (6) and the lower long forging milling cutter (8) are provided with positioning holes (15), the positioning holes (15) are hinged with positioning shafts (12) arranged on the lower short cutter rest (7) and the lower long cutter rest (9), and the lower short forging milling cutter (6) and the lower long forging milling cutter (8) rotate around the positioning shafts (12) in cutter grooves on the shell (1).

Images