Three-cone expanding sleeve fixture for positioning inner hole of super-long thin-wall sleeve workpiece

Abstract

The utility model discloses a kind of three taper expansion sleeve clamps for positioning inner hole of super-long thin-wall sleeve class workpiece, including taper spindle expansion sleeve unit, clamping screw is further provided with in taper spindle, taper spindle includes clamping section, single taper section and double taper section connected in turn, and through cavity is further provided in taper spindle along its axis direction;Expansion sleeve unit includes single taper expansion sleeve and double taper expansion sleeve;Clamping screw is inserted from one end of taper spindle, and one end of clamping screw inserted in taper spindle is threadedly connected with the other end of taper spindle;Three taper expansion sleeve clamps for positioning inner hole of super-long thin-wall sleeve class workpiece provided by the utility model, by adopting two expansion sleeve combination positioning, one expansion sleeve is double taper expansion sleeve, one is single taper expansion sleeve, corresponding design taper spindle has three outer tapers to cooperate, such structure can solve the problem of expansion sleeve length too long and processing difficulty increase, and almost entire surface of workpiece inner hole can be positioned and expanded tightly simultaneously, increase clamping rigidity, reduce deformation when workpiece is processed.

Description

Technical Field

[0001] This utility model relates to the field of machining technology, specifically to a three-cone expansion sleeve fixture for positioning the inner hole of an ultra-long thin-walled sleeve-type workpiece. Background Technology

[0002] For sleeve-type parts requiring internal hole positioning, fixture structures typically employ fixed mandrel centering or expanding sleeve centering and clamping. Fixed mandrel structures are simple but cannot eliminate positioning gaps. Expanding sleeve fixtures, on the other hand, can center and clamp simultaneously, eliminating positioning gaps and thus achieving high positioning accuracy. If the part to be machined is an ultra-long, thin-walled component, the long internal hole of the workpiece requires contact positioning elements in the fixture to enhance rigidity and prevent deformation of the thin wall. Ordinary expanding sleeve structures, due to their excessive length, cannot meet machining requirements. While fixed mandrel fixtures are simple in structure, positioning gaps introduce positioning errors, affecting the workpiece's machining accuracy. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a three-cone expansion sleeve fixture for positioning the inner hole of ultra-long thin-walled sleeve-type workpieces, and to solve the problem that there is no fixture in the existing technology that can be applied to the processing of ultra-long thin-walled parts.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a three-cone expansion sleeve clamp for positioning the inner hole of an ultra-long thin-walled sleeve-type workpiece, including a tapered mandrel and an expansion sleeve unit sleeved on the outside of the tapered mandrel. A clamping screw is also inserted inside the tapered mandrel. The tapered mandrel includes a clamping section, a single-cone section and a double-cone section connected in sequence. The tapered mandrel also has a through cavity along its own axial direction.

[0005] The expansion sleeve unit includes a single-cone expansion sleeve fitted onto a single-cone section and a double-cone expansion sleeve fitted onto a double-cone section.

[0006] The clamping screw is inserted into one end of the tapered mandrel, and the end of the clamping screw inserted into the tapered mandrel is threadedly connected to the other end of the tapered mandrel.

[0007] The clamping screw can drive the tapered mandrel to move circumferentially, thereby causing the expansion sleeve unit to expand radially.

[0008] This utility model also has the following technical features:

[0009] The outer surface of the single-cone section is a conical surface, and a through hole is provided along the axis, with the side with the larger diameter facing the clamping section.

[0010] The double-cone segment includes a conical surface segment, a first transition segment, and a second transition segment connected in sequence.

[0011] The outer surface of the conical section is a conical surface, and a through hole is provided along the axis, with the side with the larger diameter facing the single conical section.

[0012] Both the first transition section and the second transition section are hollow cylinders, with the diameter of the first transition section being larger than that of the second transition section.

[0013] The double-conical section also includes a conical sleeve fitted onto the outside of the second transition section. The outer surface of the conical sleeve is a conical surface, and a through hole is provided along the axis, with the side with the smaller diameter facing the first transition section.

[0014] The single-cone expansion sleeve is a hollow cylinder with a conical inner surface. The single-cone expansion sleeve is fitted onto the outer surface of the single-cone segment, and the inner surface of the single-cone expansion sleeve is in contact with the outer surface of the single-cone segment.

[0015] The double-cone expansion sleeve is a hollow cylinder with an inner surface that is a combination of conical surface-cylindrical surface-conical surface. The double-cone expansion sleeve is fitted onto the outer surface of the conical section and the conical sleeve. One conical surface of the double-cone expansion sleeve is in contact with the outer surface of the conical section, and the other conical surface is in contact with the outer surface of the conical sleeve.

[0016] A third transition section is connected between the clamping section and the single cone section. The third transition section has a square groove along its own radial direction. A pressure plate is arranged in the square groove. A threaded hole is opened in the middle of the pressure plate. The position of the threaded hole corresponds to the position of the through cavity.

[0017] The pressure plate is connected to the smaller end of the single-cone expansion sleeve via a first washer.

[0018] A fourth transition segment connects the single-cone segment and the third transition segment.

[0019] The clamping screw includes a screw head and a screw body connected together, wherein the diameter of the screw head is larger than the diameter of the screw body.

[0020] The screw head is connected to the end of the tapered sleeve with a larger outer diameter via a second washer, and the screw body passes through the through cavity and is connected to the pressure plate.

[0021] The section of the screw body away from the screw head is threaded, which mates with the threaded hole on the pressure plate.

[0022] The screw head is also provided with a center hole on the end face facing away from the screw body.

[0023] Compared with the prior art, this utility model has the following technical effects:

[0024] (I) The three-cone expansion sleeve fixture for positioning the inner hole of ultra-long thin-walled sleeve-type workpieces provided by this utility model adopts two expansion sleeves for positioning. One expansion sleeve is a double-cone expansion sleeve and the other is a single-cone expansion sleeve. The corresponding tapered mandrel has three external cones for matching. This structure can solve the problem of increased processing difficulty due to excessively long expansion sleeves. At the same time, it can position and tighten almost the entire surface of the inner hole of the workpiece, increase clamping rigidity, and reduce deformation during workpiece processing.

[0025] (II) The three-cone expansion sleeve clamp for positioning the inner hole of ultra-long thin-walled sleeve-type workpieces provided by this utility model adopts a clamping screw with threads at the end for the tightening structure of the two expansion sleeves. The threaded part is connected to the pressure plate. The right end of the screw is provided with a tightening hexagonal structure to press the right double-cone expansion sleeve. The cylindrical surface in the middle of the clamping screw and the inner hole of the tapered mandrel are precisely matched. When tightening the screw, the pressure plate at the left end pushes the left single-cone expansion sleeve to tighten the inner hole of the workpiece, while the right end of the clamping screw pushes the right double-cone expansion sleeve to tighten the inner hole of the workpiece.

[0026] (III) The three-cone expansion sleeve fixture for positioning the inner hole of ultra-long thin-walled sleeve-type workpieces provided by this utility model has three sections of outer conical surface on the tapered mandrel, which respectively cooperate with two expansion sleeves to generate positioning and tension. The cylindrical section set at the left end of the tapered mandrel is connected to the lathe spindle for clamping. Since the entire fixture is long, in order to increase the rigidity of the fixture, a center hole is set at the head of the clamping screw at the right end. When the fixture is used, one clamp and one top are used, which enhances the overall rigidity.

[0027] (IV) The three-cone expansion sleeve fixture for positioning the inner hole of ultra-long thin-walled sleeve workpieces provided by this utility model has a simple structure, is easy to operate, safe and reliable, and has strong adaptability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the internal structure of this utility model.

[0029] Figure 2 This is a schematic diagram of the external structure of this utility model.

[0030] Figure 3 This is a partial structural diagram of the present invention. Figure I .

[0031] Figure 4 This is a partial structural diagram of the present invention. Figure II .

[0032] Figure 5 for Figure 4 The corresponding external structure diagram.

[0033] Figure 6 A simplified diagram of the process of turning the outer diameter to locate the inner hole.

[0034] Figure 7This is a single-cone tie rod expansion sleeve clamp in the existing technology.

[0035] Figure 8 This refers to the existing double-cone tie rod expansion sleeve clamp.

[0036] The meanings of the labels in the attached diagram are as follows:

[0037] 1- Tapered mandrel, 2- Expansion sleeve unit, 3- Clamping screw, 4- Pressure plate, 5- First washer, 6- Second washer.

[0038] 1-1-Clamping section, 1-2-Single cone section, 1-3-Double cone section, 1-4-Third transition section, 1-5-Square groove, 1-6-Fourth transition section.

[0039] 2-1-Single cone expansion sleeve, 2-2-Double cone expansion sleeve.

[0040] 3-1-Screw head, 3-2-Screw body, 3-3-Center hole.

[0041] 1-3-1-Cone section, 1-3-2-First transition section, 1-3-3-Second transition section, 1-3-4-Cone sleeve.

[0042] 7-Single cone tie rod, 8-Single cone body, 9-Positioning seat, 10-Workpiece, 11-Single cone expansion sleeve.

[0043] 12-Base, 13-Connecting rod, 14-Double cone body, 15-Support, 16-Workpiece, 17-Double cone expansion sleeve, 18-Double cone tie rod.

[0044] The specific content of this utility model will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0045] Unless otherwise specified, all components in this invention are made from components known in the prior art.

[0046] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0047] Example 1:

[0048] This embodiment provides a three-cone expansion sleeve fixture for positioning the inner hole of an ultra-long, thin-walled sleeve-type workpiece, such as... Figures 1-5 As shown, it includes a tapered mandrel 1 and an expansion sleeve unit 2 sleeved on the outside of the tapered mandrel 1. A clamping screw 3 is also inserted inside the tapered mandrel 1. The tapered mandrel 1 includes a clamping section 1-1, a single tapered section 1-2 and a double tapered section 1-3 connected in sequence. The tapered mandrel 1 also has a through cavity along its own axis.

[0049] The expansion sleeve unit 2 includes a single-cone expansion sleeve 2-1 fitted onto the single-cone section 1-2 and a double-cone expansion sleeve 2-2 fitted onto the double-cone section 1-3.

[0050] The clamping screw 3 is inserted into one end of the tapered mandrel 1, and the end of the clamping screw 3 inserted into the tapered mandrel 1 is threadedly connected to the other end of the tapered mandrel 1.

[0051] The clamping screw 3 can drive the tapered mandrel 1 to move circumferentially, thereby causing the expansion sleeve unit 2 to expand radially.

[0052] The inner conical surface of the single-tapered expansion sleeve 2-1 matches the outer conical surface of the tapered mandrel 1. The external thread section of the clamping screw 3 connects to the hole in the pressure plate 4. The pressure plate 4 is installed in the square groove of the tapered mandrel, and the first washer 5 is connected to it by a screw 9. When the clamping screw 3 rotates to clamp, the square groove 1-5 of the tapered mandrel 1 limits the pressure plate 4, allowing it to move only linearly. This converts the rotation of the clamping screw 3 into linear movement of the pressure plate 2. By pushing the first washer 5, the single-tapered expansion sleeve 2-1 is then pushed to tighten, clamping the inner hole of the workpiece. The clamping force of the entire fixture is equivalent to the rotation of one part of the clamping screw 3, which drives the two expansion sleeves to simultaneously tighten the inner hole of the workpiece.

[0053] The fixture structure designed in this embodiment is a lathe fixture. The clamping section 1-1 is clamped on a three-jaw chuck. The center hole 3-3 on the end face of the screw head 3-1 matches and is positioned and tightened with the lathe tail center. The through cavity of the tapered mandrel 1 and the outer circle of the clamping screw 2 are matched to ensure that the center is coaxial.

[0054] The single-cone expansion sleeve 2-1 and the double-cone expansion sleeve 2-2 expand under the push of the corresponding clamping force, centering and clamping the inner hole of the workpiece.

[0055] The tensioning force of the double-cone expansion sleeve 2-2 comes from the fact that when the clamping screw 3 is tightened, the left end face of the outer hexagon pushes the second washer 6, and then pushes the end face of the cone sleeve 1-3-4, so that the right end of the double-cone expansion sleeve 2-2 is tightened. At the same time, the clamping component force generated to the right end causes the right end cone hole to move along the tapered cylindrical section of the tapered mandrel 1 and tighten the inner hole of the workpiece.

[0056] The tensioning force of the single-tapered expansion sleeve 2-1 comes from the structure of the clamping screw 3, the pressure plate 4, and the first washer 5. The left end of the clamping screw 3 is a threaded section, which is threaded to the pressure plate 4. A square groove 1-5 is machined on the outer circle of the tapered mandrel 1 for mounting the pressure plate 4. When the clamping screw 3 is tightened, the limiting effect of the square groove 1-5 makes the pressure plate 4 move only in a straight line and not rotate, thus generating an axial clamping force. This force is transmitted to the left end face of the single-tapered expansion sleeve 2-1 through the connected first washer 5, causing it to slide along the tapered cylindrical section of the left end of the tapered mandrel, positioning and tightening the inner hole of the workpiece.

[0057] This three-cone expansion sleeve fixture structure design ensures that the inner hole surface of this ultra-long thin-walled sleeve-type workpiece is almost entirely in contact with the positioning component and is tightened, thereby enhancing the rigidity of the fixture and effectively reducing workpiece clamping deformation and machining errors.

[0058] As a preferred embodiment:

[0059] The outer surface of the single conical section 1-2 is a conical surface, and a through hole is provided along the axis, with the side with the larger diameter facing the clamping section 1-1.

[0060] The double-conical segment 1-3 includes a conical segment 1-3-1, a first transition segment 1-3-2, and a second transition segment 1-3-3 connected in sequence.

[0061] The outer surface of the conical section 1-3-1 is a conical surface, and a through hole is provided along the axis, with the side with the larger diameter facing the single conical section 1-2.

[0062] The first transition segment 1-3-2 and the second transition segment 1-3-3 are both hollow cylinders, and the diameter of the first transition segment 1-3-2 is larger than the diameter of the second transition segment 1-3-3.

[0063] The double-conical section 1-3 also includes a conical sleeve 1-3-4 fitted onto the outside of the second transition section 1-3-3. The outer surface of the conical sleeve 1-3-4 is a conical surface, and a through hole is provided along the axis, with the side with the smaller diameter facing the first transition section 1-3-2.

[0064] As a preferred embodiment:

[0065] The single-cone expansion sleeve 2-1 is a hollow cylinder with a conical inner surface. The single-cone expansion sleeve 2-1 is fitted onto the outer surface of the single-cone section 1-2, and the inner surface of the single-cone expansion sleeve 2-1 is in contact with the outer surface of the single-cone section 1-2.

[0066] The double-cone expansion sleeve 2-2 is a hollow cylinder with an inner surface that is a combination of a conical surface, a cylindrical surface, and a conical surface. The double-cone expansion sleeve 2-2 is fitted onto the outer surfaces of the conical section 1-3-1 and the conical sleeve 1-3-4. One conical surface of the double-cone expansion sleeve 2-2 is in contact with the outer surface of the conical section 1-3-1, and the other conical surface is in contact with the outer surface of the conical sleeve 1-3-4.

[0067] As a preferred embodiment:

[0068] A third transition section 1-4 is connected between the clamping section 1-1 and the single cone section 1-2. The third transition section 1-4 has a square groove 1-5 along its own radial direction. A pressure plate 4 is arranged in the square groove 1-5. A threaded hole is opened in the middle of the pressure plate 4. The position of the threaded hole corresponds to the position of the through cavity.

[0069] The pressure plate 4 is connected to the smaller end of the single cone expansion sleeve 2-1 via the first washer 5.

[0070] A fourth transition segment 1-6 is also connected between the single cone segment 1-2 and the third transition segment 1-4.

[0071] As a preferred embodiment:

[0072] The clamping screw 3 includes a screw head 3-1 and a screw body 3-2 connected together, wherein the diameter of the screw head 3-1 is larger than the diameter of the screw body 3-2.

[0073] The screw head 3-1 is connected to the larger outer diameter end of the tapered sleeve 1-3-4 via the second washer 6, and the screw body 3-2 passes through the through cavity and is connected to the pressure plate 4.

[0074] The screw body 3-2, away from the screw head 3-1, is threaded and engages with the threaded hole on the pressure plate 4.

[0075] As a preferred embodiment:

[0076] The screw head 3-1 is provided with a top hole 3-3 on the end face facing away from the screw body 3-2.

[0077] The specific working process of this utility model:

[0078] The problem solved in this embodiment is the positioning and clamping of the inner hole of an extended thin-walled sleeve-type workpiece.

[0079] like Figure 6 As shown, the part has a wall thickness of 1 and a length of 272. This process requires positioning the inner hole to machine the outer circle, ensuring the outer circle dimensions, coaxiality, and cylindricity requirements.

[0080] like Figure 7 As shown, 7-single cone tie rod, 8-single cone body, 9-positioning seat, 10-workpiece, 11-single cone expansion sleeve.

[0081] When in use, tighten the single-cone tie rod 7. The single-cone tie rod 7 drives the single-cone expansion sleeve 11 to expand, clamping the workpiece 10 from the inside out. The single-cone tie rod expansion sleeve fixture is one of the conventional internal hole positioning fixture structures. The expansion sleeve is generally 50 mm long. If it is lengthened, the difficulty of processing the expansion sleeve and the tensioning stroke will be affected.

[0082] like Figure 8 As shown, 12-base, 13-connecting rod, 14-double cone body, 15-support, 16-workpiece, 17-double cone expansion sleeve, 18-double cone tie rod.

[0083] When in use, tighten the double-cone tie rod 18. The double-cone tie rod 18 drives the double-cone expansion sleeve 17 to expand, clamping the workpiece 16 from the inside out. The second type of conventional internal hole positioning fixture uses a double-cone tie rod expansion sleeve fixture. The length of the double-cone expansion sleeve is generally 50. If it is lengthened, it will increase the difficulty of machining the expansion sleeve and the tapered shaft. In addition, the middle part of the double cone is suspended, which results in poor rigidity of the middle machining part of the workpiece and reduced support, which will cause machining errors in the middle part of the workpiece.

[0084] After careful analysis of the workpiece's structural characteristics and the fixture's positioning and clamping requirements, we designed the following fixture scheme ( Figures 1-5 ):

[0085] The implementation process of this project mainly consists of the following parts:

[0086] 1) Analysis of workpiece structural characteristics, machining requirements, and similar fixture structures.

[0087] like Figure 6 As shown, this workpiece requires machining of the outer cylindrical surface using the inner hole for positioning. The workpiece is 272 mm long, with an inner hole diameter of 78 mm, an outer cylindrical diameter of 80 mm, and a wall thickness of only 1 mm. It belongs to the category of ultra-long thin-walled sleeve parts.

[0088] For sleeve-type parts requiring internal hole positioning, fixture structures typically employ fixed mandrel centering or expanding sleeve centering and clamping. Fixed mandrel structures are simple but cannot eliminate positioning gaps. Expanding sleeve fixtures, on the other hand, can center and clamp simultaneously, eliminating positioning gaps and thus achieving high positioning accuracy. If the part to be machined is an ultra-long, thin-walled component, the long internal hole of the workpiece requires contact positioning elements in the fixture to enhance rigidity and prevent deformation of the thin wall. Ordinary expanding sleeve structures, due to their excessive length, cannot meet machining requirements. While fixed mandrel fixtures are simple in structure, positioning gaps introduce positioning errors, affecting the workpiece's machining accuracy.

[0089] This project uses an expansion sleeve structure to center and clamp the inner hole of the workpiece. The challenge lies in how to support, center, and clamp the inner hole of the workpiece along its entire length to enhance rigidity and meet processing requirements.

[0090] The fixture structure designed in this project is a lathe fixture. The left end clamping section 1-1 of the tapered mandrel 1 of the lathe fixture is clamped on the three-jaw chuck. The center hole 3-3 on the end face of the clamping screw 3 is 60°. The center hole 3-3 is matched and positioned with the tail center of the lathe. The through cavity of the tapered mandrel 1 and the outer circle of the clamping screw 3 are matched to ensure that the center is coaxial.

[0091] To ensure proper positioning and support of the workpiece's inner hole surface, the positioning surface of the positioning element needs to be extended as much as possible. However, conventional expansion sleeves suffer from poor manufacturability and significant machining difficulties when made to the length of the workpiece's inner hole. Therefore, we adopted a three-conical expansion sleeve positioning structure.

[0092] Two tapered cylinders are machined on the outer circle of the tapered mandrel 1, namely a single tapered section 1-2 and a tapered surface section 1-3-1. The single tapered expansion sleeve 2-1 is matched with the tapered surface of its single tapered section 1-2. A double tapered expansion sleeve 2-2 is set at the right end, one end of which matches the tapered surface section 1-3-1, and the other end of which the inner tapered part matches the outer tapered surface of the tapered sleeve 1-3-4.

[0093] The outer locating surface formed by two expansion sleeves contacts and positions the entire surface of the workpiece's inner hole, providing support. This structural design reduces the manufacturing difficulty of the expansion sleeves and ensures that the entire inner surface of the thin-walled sleeve can effectively contact and position the workpiece, thus reducing deformation during the machining of the thin-walled sleeve workpiece.

[0094] The left end of the double-cone expansion sleeve 2-2 mates with the corresponding taper on the tapered mandrel, while the right end mates with the outer taper of the tapered sleeve 1-3-4. When the clamping screw 3 is tightened, the resulting clamping force pushes the tapered sleeve 1-3-4 to the left, thus opening the right end of the double-cone expansion sleeve 2-2. Simultaneously, the left end also generates radial tension as it moves along the tapered mandrel 1. The second washer 6 ensures that when the clamping screw 3 is tightened, it only generates a linear clamping force on the end face of the tapered sleeve, without generating a force that causes it to rotate, thereby reducing fixture positioning errors.

[0095] The above technical solutions are only preferred embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions that can be conceived by those skilled in the art without creative effort within the technical scope disclosed in this utility model are covered within the protection scope of this utility model.

Claims

1. A three-tapered expansion sleeve fixture for positioning the inner hole of an ultra-long thin-walled sleeve-type workpiece, comprising a tapered mandrel (1) and an expansion sleeve unit (2) sleeved on the outside of the tapered mandrel (1), wherein a clamping screw (3) is also provided inside the tapered mandrel (1), characterized in that, The tapered mandrel (1) includes a clamping section (1-1), a single tapered section (1-2), and a double tapered section (1-3) connected in sequence. The tapered mandrel (1) also has a through cavity along its own axis. The expansion sleeve unit (2) includes a single-cone expansion sleeve (2-1) sleeved on the single-cone section (1-2) and a double-cone expansion sleeve (2-2) sleeved on the double-cone section (1-3); The clamping screw (3) is inserted into one end of the tapered spindle (1), and the end of the clamping screw (3) inserted into the tapered spindle (1) is threadedly connected to the other end of the tapered spindle (1); The clamping screw (3) can drive the tapered mandrel (1) to move circumferentially to drive the expansion sleeve unit (2) to expand radially.

2. The three-cone expansion sleeve fixture for positioning the inner hole of ultra-long thin-walled sleeve-type workpieces as described in claim 1, characterized in that, The outer surface of the single conical section (1-2) is a conical surface, and a through hole is provided along the axis, with the side with the larger diameter facing the clamping section (1-1); The double-cone segment (1-3) includes a conical segment (1-3-1), a first transition segment (1-3-2), and a second transition segment (1-3-3) connected in sequence; The outer surface of the conical section (1-3-1) is a conical surface, and a through hole is provided along the axis, with the side with the larger diameter facing the single conical section (1-2); The first transition section (1-3-2) and the second transition section (1-3-3) are both hollow cylinders, and the diameter of the first transition section (1-3-2) is larger than the diameter of the second transition section (1-3-3). The double-conical section (1-3) further includes a conical sleeve (1-3-4) fitted onto the outside of the second transition section (1-3-3). The outer surface of the conical sleeve (1-3-4) is a conical surface, and a through hole is provided along the axis, with the smaller diameter side facing the first transition section (1-3-2).

3. The three-cone expansion sleeve fixture for positioning the inner hole of ultra-long thin-walled sleeve-type workpieces as described in claim 2, characterized in that, The single-cone expansion sleeve (2-1) is a hollow cylinder with a conical inner surface. The single-cone expansion sleeve (2-1) is fitted onto the outer surface of the single-cone section (1-2), and the inner surface of the single-cone expansion sleeve (2-1) is in contact with the outer surface of the single-cone section (1-2). The double-cone expansion sleeve (2-2) is a hollow cylinder with an inner surface that is a combination of a conical surface, a cylindrical surface, and a conical surface. The double-cone expansion sleeve (2-2) is fitted onto the outer surface of the conical section (1-3-1) and the conical sleeve (1-3-4). One conical surface of the double-cone expansion sleeve (2-2) is in contact with the outer surface of the conical section (1-3-1), and the other conical surface is in contact with the outer surface of the conical sleeve (1-3-4).

4. The three-cone expansion sleeve fixture for positioning the inner hole of ultra-long thin-walled sleeve-type workpieces as described in claim 3, characterized in that, A third transition section (1-4) is connected between the clamping section (1-1) and the single cone section (1-2). The third transition section (1-4) has a square groove (1-5) along its own radial direction. A pressure plate (4) is arranged in the square groove (1-5). A threaded hole is opened in the middle of the pressure plate (4). The position of the threaded hole corresponds to the position of the through cavity. The pressure plate (4) is connected to the smaller end of the single cone expansion sleeve (2-1) via the first washer (5); A fourth transition segment (1-6) is also connected between the single cone segment (1-2) and the third transition segment (1-4).

5. The three-cone expansion sleeve fixture for positioning the inner hole of ultra-long thin-walled sleeve-type workpieces as described in claim 4, characterized in that, The clamping screw (3) includes a screw head (3-1) and a screw body (3-2) connected together, wherein the diameter of the screw head (3-1) is larger than the diameter of the screw body (3-2); The screw head (3-1) is connected to the larger outer diameter end of the tapered sleeve (1-3-4) through the second washer (6), and the screw body (3-2) passes through the through cavity and is connected to the pressure plate (4); The screw body (3-2) is threaded at a section away from the screw head (3-1), which engages with the threaded hole on the pressure plate (4).

6. The three-cone expansion sleeve fixture for positioning the inner hole of ultra-long thin-walled sleeve-type workpieces as described in claim 5, characterized in that, The screw head (3-1) is also provided with a top hole (3-3) on the end face facing away from the screw body (3-2).

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