High-precision double-expanding fixture for long inner hole sleeve

Abstract

This invention discloses a high-precision double-tensioning jig for a long inner hole sleeve, comprising a base, a double-tapered mandrel fixed on the base, a pull shaft, and a pull sleeve. The pull sleeve is fixedly connected to the pull shaft by a fastener passing through the double-tapered mandrel. A lower expansion sleeve is fitted onto the lower part of the double-tapered mandrel, and the lower end of the lower expansion sleeve engages with the upper part of the pull sleeve. An upper expansion sleeve is engaged with the top of the double-tapered mandrel. A conical pull rod extends longitudinally through the upper expansion sleeve and the double-tapered mandrel. A limit block is fixedly connected to the lower end of the conical pull rod. A positioning hole for engaging the limit block is provided on the upper part of the pull shaft. An elastic component is provided between the limit block and the upper wall of the double-tapered mandrel. When the pull shaft moves downward, it indirectly drives the lower expansion sleeve to squeeze the double-tapered mandrel and tension the lower part of the sleeve workpiece. The contracting elastic component spontaneously drives the conical pull rod downward, causing the head of the push rod to squeeze and tension the upper part of the workpiece with the upper sleeve, thereby achieving stable clamping of the entire sleeve.

Description

Technical Field

[0001] This invention relates to the field of machining technology for long inner hole sleeves, and in particular to a high-precision double-tensioning machine clamp for long inner hole sleeves. Background Technology

[0002] Currently, with the development of technology, higher requirements are being placed on the machining accuracy and reliability of parts, and the clamping stability and accuracy requirements for fixtures used to position workpieces are also increasing. Among the many types of workpieces, long inner hole sleeves are the most difficult to clamp due to their deep and long inner holes, and conventional expansion sleeves cannot achieve such lengths, making it difficult to meet the clamping requirements of these parts.

[0003] Currently, a conventional fixture includes a base, a tapered body fixed on the base, an elastic expansion sleeve fitted on the tapered body, and a transmission structure inside the fixture for connecting and driving the expansion sleeve to move along the tapered body. When the machine tool drives the spindle and drives the expansion sleeve to move along the outer conical surface of the tapered body through the connected transmission structure, the expansion sleeve expands due to the radial force from the surface of the tapered body. The expanded expansion sleeve then abuts against the inner side of the workpiece to be processed, thereby fixing the workpiece.

[0004] To ensure the elastic properties of radial expansion or contraction, expansion sleeves are typically short in length. However, this structural feature makes it difficult to meet the clamping requirements of long internal sleeve-type parts. Therefore, conventional fixtures cannot provide sufficient clamping force or maintain stable clamping accuracy, leading to unstable clamping of these parts and affecting their machining accuracy.

[0005] Currently, there is no specialized fixture capable of stably clamping long internal sleeve-shaped parts. Therefore, existing technology needs further development. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a high-precision double-tensioning clamp for long inner hole sleeves. This clamp is designed specifically for the structure of long inner hole sleeves. By using an upper and lower tensioning sleeve that respectively cooperate with a double-tapered mandrel, it achieves synchronous positioning of different parts of the long inner hole sleeve, resulting in stable clamping and high precision.

[0007] This invention provides the following technical solutions:

[0008] This invention provides a high-precision double-tensioning machine tool fixture for a long inner hole sleeve, comprising a base for fixed connection with a machine tool, a double-tapered mandrel fixed above the base, a pull shaft for axial movement between the double-tapered mandrel and the base, and a pull sleeve located above the double-tapered mandrel. The pull sleeve is fixedly connected to the pull shaft by fasteners penetrating the double-tapered mandrel. A rod portion for connection with the machine tool spindle is provided at the lower part of the pull shaft. A lower tensioning sleeve is fitted on the lower cone of the double-tapered mandrel, and the lower end of the lower tensioning sleeve is connected to... The upper part of the pull sleeve is snapped in place, and the top of the double-tapered mandrel is snapped into the rising sleeve. A tapered pull rod runs longitudinally through the rising sleeve and the double-tapered mandrel. The taper of the outer wall of the head of the tapered pull rod is consistent with the taper of the inner tapered hole of the rising sleeve. The taper of the outer wall of the lower part of the double-tapered mandrel is consistent with the taper of the inner hole of the lower rising sleeve. The lower end of the tapered pull rod is fixedly connected to a limit block. The upper part of the pull shaft is provided with a positioning hole for docking with the limit block. An elastic component is provided between the limit block and the upper wall of the double-tapered mandrel.

[0009] When the pull shaft moves outward under the action of external force, the lower expansion sleeve is driven by the connected pull sleeve to press down on the lower conical outer wall of the double-tapered mandrel. The lower expansion sleeve expands and tightens the lower inner surface of the sleeve workpiece. At the same time, the elastic component in the contracted state expands downward under the action of elastic restoring force, pushing the lower end of the cone pull rod. The head of the push pull rod presses down and expands the upper sleeve. The upper sleeve tightens the upper inner surface of the sleeve workpiece, realizing the clamping of the sleeve by the fixture.

[0010] Preferably, in the high-precision double-tensioning machine clamp for the long inner sleeve, the upper sleeve and / or the lower sleeve are formed by at least two circumferentially distributed metal clamping blocks and elastic rubber blocks that bond adjacent clamping blocks; the central through hole portion or the entire upper sleeve and the lower sleeve are provided with a tapered hole wall.

[0011] Preferably, in the high-precision double-tensioning machine clamp for the long inner hole sleeve, the double-tapered mandrel is provided with a second through hole along the central axis for the tapered tie rod to pass through, and the lower part of the double-tapered mandrel is provided with a receiving cavity communicating with the second through hole. The elastic component and the limiting block are located in the receiving cavity, and the elastic component is limited in the space between the limiting block and the top wall of the receiving cavity.

[0012] Preferably, in the high-precision double-tensioning machine clamp for the long inner sleeve, the elastic component is a disc spring, a rectangular spring, or a cylindrical compression spring; the upper part of the limiting block is screwed to the lower end of the conical pull rod; and the lower part of the limiting block is engaged in the positioning hole of the pull shaft.

[0013] Preferably, in the high-precision double-tensioning machine clamp for the long inner sleeve, the cross-sectional shape of the limiting block is a non-circular anti-rotation shape; or, the side of the limiting block is provided with an anti-rotation protrusion, and the positioning hole is provided with an anti-rotation hole for engaging the anti-rotation protrusion.

[0014] Preferably, in the high-precision double-tensioning machine fixture for the long inner hole sleeve, the base includes a base flange and a fixed seat fixed above the base flange. The bottom surface of the fixed seat is provided with a first through hole for the rod part of the pull shaft to pass through. An annular cover-type support plate is also fixedly connected above the base. The top surface of the support plate is provided with a plane for supporting the sleeve workpiece. The top of the support plate is provided with a fourth through hole for the lower expansion sleeve to pass through. A gap is provided between the inner wall of the fourth through hole and the lower expansion sleeve for the lower expansion sleeve to expand and contract.

[0015] Preferably, in the high-precision double-tensioning machine clamp with long inner hole sleeve, multiple connecting arms extend horizontally from the upper part of the pull shaft, and a rod extends downward from the center of the bottom of the pull shaft. Connecting holes are provided on the connecting arms respectively. The upper and lower ends of a fastener are screwed to the pull sleeve and the connecting arms respectively, and the middle part of the fastener freely passes through the bottom of the double-tapered mandrel.

[0016] Preferably, in the high-precision double-tensioning machine clamp with long inner hole sleeve, a stepped hole is provided in the center of the top surface of the fixed seat. The first-level slot at the bottom of the stepped hole matches the rod part of the pull shaft. The cross-section of the second-level slot of the stepped hole matches the upper shape of the pull shaft. The depth of the second-level slot is greater than the thickness of the upper part of the pull shaft, so that the pull shaft can move up and down within the working range. The bottom of the double-tapered mandrel is embedded in the third-level slot of the stepped hole, and the bottom of the double-tapered mandrel is fixedly connected to the wall of the third-level slot.

[0017] Preferably, in the high-precision double-tensioning machine clamp for the long inner hole sleeve, the upper part of the central through hole of the rising sleeve is provided with a tapered hole, and a first snap-fit ​​part for snapping the top of the double-tapered mandrel is provided on the lower side wall of the central through hole of the rising sleeve; a second snap-fit ​​part that cooperates with the first snap-fit ​​part is provided on the top of the double-tapered mandrel, and a support part for supporting the bottom of the rising sleeve is provided on the lower side of the second snap-fit ​​part; the bottom of the central through hole of the rising sleeve is radially expanded to form a support hole for snapping the support part.

[0018] Preferably, in the high-precision double-tensioning machine clamp with long inner hole sleeve, a spacer is sleeved on the upper part of the conical tie rod, and a third through hole is provided on the spacer for the conical tie rod to pass through. The spacer is located between the upper sleeve and the lower sleeve.

[0019] The high-precision double-tensioning machine clamp for long inner hole sleeves provided by this invention has the following beneficial effects:

[0020] 1. The high-precision double-tensioning machine clamp for long inner hole sleeves has a simple structure. It can drive the upper and lower tensioning sleeves to work simultaneously through only one set of external drive mechanism (driven by the machine tool spindle), so as to realize the synchronous positioning of different parts of the long inner hole sleeve. It has a large clamping force and stable clamping accuracy, which greatly improves the machining accuracy of long inner hole sleeves.

[0021] 2. The upper and lower expansion sleeves are made of rubber expansion sleeves, which have a clamping force 2-3 times that of all-steel slotted expansion sleeves. The clamping force is kept parallel and uniformly applied to the workpiece, which is not easy to damage the workpiece, and has a long service life and high work efficiency.

[0022] 3. The double-tapered mandrel of this invention is designed based on the structure of a long inner hole sleeve, and can be adjusted according to the length specifications of the long inner hole sleeve. The double-tapered mandrel engages with the lower expansion sleeve through the lower cone, and the upper part of the double-tapered mandrel sets the upper expansion sleeve, with the head of the tapered tie rod engaging with the upper expansion sleeve. Furthermore, the elastic component and limiting block at the bottom of the tapered railing ensure synchronous operation of the upper and lower expansion sleeves. This ingenious design greatly simplifies the structure of the clamp. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the high-precision double-tensioning machine clamp for the long inner hole sleeve in Embodiment 1 of the present invention;

[0024] Figure 2 This is a schematic cross-sectional view of the high-precision double-tensioning machine clamp for the long inner sleeve.

[0025] Figure 3 This is an exploded view of the structure of the high-precision double-tensioning machine clamp for the long inner hole sleeve;

[0026] Figure 4 A schematic diagram of the cross-sectional structure of the rising sleeve;

[0027] Figure 5 An exploded view of the internal structure of a high-precision double-tensioning machine clamp with a long inner hole sleeve.

[0028] Figure 6 A three-dimensional structural diagram of a high-precision double-tensioning machine clamp with a long inner hole sleeve after eliminating the upper multi-part structure;

[0029] The reference numerals in the attached figures are explained as follows:

[0030] Base 1, base flange 101, fixed seat 102, stepped hole 102a, double taper mandrel 2, second through hole 21, accommodating cavity 22, second snap-fit ​​part 23, support part 24, pull shaft 3, rod part 31, positioning hole 32, connecting arm 33, pull sleeve 4, lower expansion sleeve 5, upper expansion sleeve 6, tapered hole 61, first snap-fit ​​part 62, support hole 63, tapered pull rod 7, limit block 8, elastic component 9, spacer 10, fastener 11, support plate 12, fourth through hole 12a. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist therebetween. When an element is described as being "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements may exist therebetween. The terms indicating orientation or positional relationship used in this specification are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the present invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items. Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Example 1

[0033] like Figures 1-3 As shown, this embodiment provides a high-precision double-tensioning machine tool fixture for a long inner hole sleeve. The fixture includes a base 1 for fixed connection with a machine tool, a double-tapered mandrel 2 fixed at the center above the base, a pull shaft 3 located in the cavity formed between the double-tapered mandrel and the base and capable of axial movement, and a pull sleeve 4 located above the double-tapered mandrel. The pull sleeve 4 is fixedly connected to the pull shaft 3 by a fastener 11 passing through the double-tapered mandrel. A rod portion 31 for connecting with the machine tool spindle is provided at the lower part of the pull shaft.

[0034] The lower vertebral body of the double-tapered mandrel 2 is fitted with a lower expansion sleeve 5, the lower end of which is engaged with the upper part of the pull sleeve 4. The top of the double-tapered mandrel 2 is engaged with an upper expansion sleeve 6. A conical pull rod 7 extends longitudinally through the upper expansion sleeve and the double-tapered mandrel. The taper of the outer wall of the head of the conical pull rod is consistent with the taper of the inner conical hole of the upper expansion sleeve, and the taper of the outer wall of the lower vertebral body of the double-tapered mandrel 2 is consistent with the taper of the inner hole of the lower expansion sleeve 5. The lower end of the conical pull rod is fixedly connected to a limiting block 8. The upper part of the pull shaft 3 is provided with a positioning hole 32 for engaging the limiting block. A compressed elastic component 9 is provided between the limiting block 8 and the upper wall of the double-tapered mandrel. This structure allows the elastic component 9 to recover its deformation downwards and automatically push the limiting block and the connected conical pull rod 7 downwards when the pull shaft 3 moves downwards away from the double-tapered mandrel.

[0035] Before operation, connect the rod of pull shaft 3 to the machine tool spindle, and install the long inner hole sleeve on the upper part of the fixture, so that the upper sleeve and the lower sleeve are located in the upper inner cavity and the lower inner cavity of the sleeve, respectively, so that the two sleeves can synchronously clamp and position different parts of the sleeve.

[0036] During operation, under the external force of the machine tool spindle, the pull shaft moves outward (i.e. downward). Through the connected pull sleeve 4, it drives the lower expansion sleeve 5 to press down on the lower conical outer wall of the double-tapered mandrel. The lower expansion sleeve 5 expands radially (opens up) and tightens the lower inner surface of the sleeve workpiece. At the same time, the elastic component 9 in the contracted state expands downward under the action of elastic restoring force and pushes the lower end of the cone head pull rod 7. The head of the push head pull rod presses down and opens the upper sleeve 6. The upper sleeve 6 tightens the upper inner surface of the sleeve workpiece. Thus, the clamping of the sleeve by the fixture is achieved through the combined action of the upper sleeve 6 and the lower expansion sleeve.

[0037] When the work is finished, the pull shaft 3 pushes the pull sleeve 4 upward, which in turn causes the lower expansion sleeve 5 to move upward and radially retract to return to its original shape. At this time, the upward-moving pull shaft 3 pushes the conical pull rod 7 upward, and the upper expansion sleeve 6 returns to its original deformation. Meanwhile, the elastic component 9 is compressed due to the pressure of the limiting block 8. At this point, both the upper and lower expansion sleeves return to their original shapes, unlocking the clamping of the inner wall of the sleeve workpiece, and the workpiece can be easily removed.

[0038] The above-mentioned high-precision double-tensioning machine clamp for long inner hole sleeves has a simple structure and is easy to use. It can drive the upper and lower tensioning sleeves to work simultaneously through only one external drive mechanism (driven by the machine tool spindle), so as to achieve synchronous positioning of different parts of the long inner hole sleeve. It has a large clamping force and stable clamping accuracy, which greatly improves the machining accuracy of the long inner hole sleeve.

[0039] In this embodiment, preferably, the upper sleeve 6 and the lower sleeve 7 are formed by at least two circumferentially distributed metal clamping blocks and elastic rubber blocks bonded to adjacent clamping blocks; the central through hole portion or the entirety is provided with a tapered hole wall. The clamping force of this rubber sleeve is 2-3 times that of an all-steel slotted sleeve, and the clamping force is kept parallel and uniformly applied to the workpiece, resulting in a long service life and high working efficiency. In other embodiments, the upper sleeve 6 and the lower sleeve 7 can adopt other existing radially expandable sleeves, and are not limited to the specific method of this embodiment.

[0040] like Figure 4 As shown, to better accommodate the tapered tie rod, the upper part of the central through hole of the rising sleeve 6 is configured as a tapered hole 61. To ensure the rising sleeve is stably fixed to the top of the double-tapered mandrel, a first engaging portion 62 for engaging the top of the double-tapered mandrel is provided on the lower side wall of the central through hole of the rising sleeve. Correspondingly, a second engaging portion is provided on the top of the double-tapered mandrel to engage with the first engaging portion 62, and a support portion 23 for supporting the bottom of the rising sleeve is provided on the lower side of the second engaging portion. The bottom of the central through hole of the rising sleeve expands radially to form a support hole 63 for engaging the support portion. The aforementioned first engaging portion and second engaging portion can be structures formed by outward protrusions or inward recesses of the side walls or bottom walls of corresponding components, and are not limited to the structures shown in the attached drawings.

[0041] In this embodiment, as Figure 3 As shown, the double-tapered mandrel has a second through hole 21 along its central axis for the conical head pull rod to pass through. The lower part of the double-tapered mandrel has a receiving cavity communicating with the second through hole. The elastic component 9 and the limiting block 8, which are located at the bottom of the conical head pull rod, are located in the receiving cavity. The elastic component is confined within the space between the limiting block 8 and the top wall of the receiving cavity, and it can extend and retract within the working range. By pushing and pulling the conical head railing, the working state of the rising sleeve 6 can be controlled.

[0042] In this embodiment, the elastic component 9 consists of multiple overlapping disc springs, and the conical pull rod is configured to pass through the central hole of the disc springs. In other embodiments, the elastic component can also be a rectangular spring, a cylindrical compression spring, or a similar elastic element. The upper part of the limiting block 8 is screwed to the lower end of the conical pull rod (or fixed in other ways); the lower part of the limiting block is engaged in the positioning hole 32 of the pull shaft.

[0043] Preferably, to prevent the pull shaft 3 from rotating relative to the limiting block during operation, the cross-sectional shape of the limiting block is a non-circular anti-rotation structure, such as a polygon or other shape; alternatively, anti-rotation protrusions are provided on the side of the limiting block, and anti-rotation holes for engaging the anti-rotation protrusions are provided in the positioning holes. Both solutions provide anti-rotation features that ensure accurate alignment between the pull shaft and the limiting block.

[0044] In this embodiment, as Figure 3As shown, the pull sleeve 4 has a central mounting hole 41, and the side wall of the mounting hole extends horizontally to form a snap-fit ​​protrusion 42. The bottom cross-section of the lower expansion sleeve 5 (which may have a snap-fit ​​foot) is consistent with the cross-sectional shape of the mounting hole. After the bottom of the lower expansion sleeve passes through the mounting hole, rotating the lower expansion sleeve causes the snap-fit ​​protrusion to snap into the snap-fit ​​groove 51 on the bottom side of the lower expansion sleeve, thereby achieving the snap-fit ​​between the pull sleeve and the lower expansion sleeve. Furthermore, the connection stability between the pull sleeve and the lower expansion sleeve can be further strengthened by adding other connections (such as screw connections).

[0045] Specifically, for ease of installation and disassembly, the base 1 includes a base flange 101 and a fixing seat 102 fixed above the base flange. The bottom surface of the fixing seat is provided with a first through hole through which the rod portion 31 of the pull shaft passes.

[0046] like Figure 2 , 3 and Figure 6 Three connecting arms 33 extend horizontally from the upper part of the pull shaft, and a rod 31 extends downward from the center of the bottom of the pull shaft. Connecting holes are provided on each connecting arm. The upper and lower ends of a fastener 11 are screwed to the pull sleeve 4 and the connecting arm 31, respectively. A movable hole is provided at the bottom of the double-tapered mandrel corresponding to the fastener, and the middle part of the fastener freely passes through the movable hole at the bottom of the double-tapered mandrel. Furthermore, to improve the vertical movement flexibility of the fastener 11, a bushing is installed in the movable hole.

[0047] To better install and secure other components, a stepped hole 102a is provided in the center of the top surface of the mounting base 102, such as... Figure 2 As shown, the first-level slot at the bottom of the stepped hole matches the rod part of the pull shaft, allowing the pull shaft rod part to pass through. The cross-section of the second-level slot of the stepped hole matches the upper shape of the pull shaft 3. The depth of the second-level slot is greater than the thickness of the upper connecting arm of the pull shaft, allowing the pull shaft 3 to move up and down within the working range. The bottom of the double-tapered mandrel 2 is embedded in the third-level slot of the stepped hole, and the bottom of the double-tapered mandrel 2 is fixedly connected to the wall of the third-level slot.

[0048] To better position the sleeve and prevent axial displacement during clamping, a ring-shaped support plate 12 is fixedly connected above the base. The top surface of the support plate has a plane for supporting the sleeve workpiece. A fourth through hole 12a is provided at the top of the support plate for the lower expansion sleeve 5 to pass through. A gap is provided between the inner wall of the fourth through hole 12a and the lower expansion sleeve 5 to allow for expansion and contraction of the lower expansion sleeve. This hollow support plate not only supports the sleeve, preventing axial displacement during clamping, but also protects the internal components from external environmental contamination or oxidation, effectively extending the service life of the fixture's core components.

[0049] In addition, a spacer 10 is fitted onto the upper part of the conical tie rod, and a third through hole is provided on the spacer for the conical tie rod to pass through. On the one hand, the spacer 10 plays a guiding role in the installation of the workpiece; on the other hand, the spacer plays a certain limiting role in the lower expansion sleeve 5. In this embodiment, the spacer is cylindrical; other cylindrical structures can also be used in other embodiments.

[0050] To prevent relative rotation between the components of the aforementioned fixture during operation, at least one anti-rotation screw is fixed to the side wall of the spacer, which secures the side wall of the spacer to the side wall of the double-tapered mandrel. Anti-rotation screws may also be installed between other contacting components.

[0051] Furthermore, at least one sealing ring is provided on the outer periphery of the shaft, and a sealing ring is also provided on the upper inner wall of the support plate.

[0052] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. It is understood that those skilled in the art can make equivalent substitutions or modifications based on the technical solutions and concepts of this invention, and all such modifications or substitutions should fall within the protection scope of the appended claims.

Claims

1. A high-precision double-tensioning machine clamp for a long inner hole sleeve, characterized in that, The device includes a base (1) for fixed connection with a machine tool, a double-tapered spindle (2) fixed above the base, a pull shaft (3) for axial movement between the double-tapered spindle and the base, and a pull sleeve (4) located above the double-tapered spindle. The pull sleeve (4) is fixedly connected to the pull shaft (3) by fasteners passing through the double-tapered spindle. A rod (31) for connection with the machine tool spindle is provided at the lower part of the pull shaft. A lower expansion sleeve (5) is fitted on the lower cone of the double-tapered spindle (2), and the lower end of the lower expansion sleeve is engaged with the upper part of the pull sleeve. The top of the double-tapered mandrel (2) is fitted with an ascending sleeve (6), and a conical pull rod (7) runs longitudinally through the ascending sleeve and the double-tapered mandrel. The taper of the outer wall of the head of the conical pull rod is consistent with the taper of the inner conical hole of the ascending sleeve, and the taper of the outer wall of the lower vertebra of the double-tapered mandrel (2) is consistent with the taper of the inner hole of the lower ascending sleeve. The lower end of the conical pull rod is fixedly connected to a limiting block (8), and the upper part of the pull shaft (3) is provided with a positioning hole (32) for docking with the limiting block. An elastic component (9) is provided between the limiting block and the upper wall of the double-tapered mandrel. When the pull shaft (3) moves outward under the action of external force, the lower expansion sleeve (5) is driven by the connected pull sleeve (4) to press down on the lower conical outer wall of the double taper mandrel. The lower expansion sleeve expands and tightens the lower inner surface of the sleeve workpiece. At the same time, the elastic component (9) in the contracted state expands downward under the action of elastic restoring force to push the lower end of the cone pull rod (7). The head of the push pull rod presses down and expands the upper sleeve (6). The upper sleeve tightens the upper inner surface of the sleeve workpiece, realizing the clamping of the sleeve by the fixture.

2. The high-precision double-tensioning machine clamp for long inner hole sleeves according to claim 1, characterized in that, The rising sleeve and / or the lower rising sleeve are formed by at least two circumferentially distributed metal clamping blocks and elastic rubber blocks that bond adjacent clamping blocks; the central through hole portion or the entire rising sleeve and the lower rising sleeve are provided with a tapered hole wall.

3. The high-precision double-tensioning machine clamp for long inner hole sleeves according to claim 2, characterized in that, The double-tapered mandrel has a second through hole (21) along its central axis for the conical head pull rod to pass through. The lower part of the double-tapered mandrel has a receiving cavity that communicates with the second through hole. The elastic component (9) and the limiting block (8) are located in the receiving cavity. The elastic component is limited in the space between the limiting block and the top wall of the receiving cavity.

4. The high-precision double-tensioning machine clamp for long inner hole sleeves according to claim 3, characterized in that, The elastic component (9) is a disc spring, a rectangular spring or a cylindrical compression spring; the upper part of the limiting block (8) is screwed to the lower end of the cone-shaped pull rod; the lower part of the limiting block is engaged in the positioning hole (32) of the pull shaft.

5. The high-precision double-tensioning machine clamp for long inner hole sleeves according to claim 4, characterized in that, The cross-sectional shape of the limiting block is non-circular to prevent rotation; or, the side of the limiting block is provided with an anti-rotation protrusion, and the positioning hole is provided with an anti-rotation hole for engaging the anti-rotation protrusion.

6. The high-precision double-tensioning machine clamp for long inner hole sleeves according to claim 1, characterized in that, The base (1) includes a base flange (101) and a fixed seat (102) fixed above the base flange. The bottom surface of the fixed seat is provided with a first through hole through which the rod part (31) of the pull shaft passes. A ring-shaped support plate (12) is also fixedly connected above the base. The top surface of the support plate is provided with a plane for supporting the sleeve workpiece. The top of the support plate is provided with a fourth through hole (12a) through which the lower expansion sleeve (5) passes. A gap is provided between the inner wall of the fourth through hole (12a) and the lower expansion sleeve (5) for the lower expansion sleeve to expand and contract.

7. The high-precision double-tensioning machine clamp for long inner hole sleeves according to claim 1, characterized in that, Multiple connecting arms (33) extend horizontally from the upper part of the pull shaft, and a rod (31) extends downward from the center of the bottom of the pull shaft. Connecting holes are provided on the connecting arms respectively. The upper and lower ends of a fastener (11) are screwed to the pull sleeve (4) and the connecting arm respectively. The middle part of the fastener freely passes through the bottom of the double-tapered mandrel.

8. The high-precision double-tensioning machine clamp for long inner hole sleeves according to claim 6, characterized in that, A stepped hole (102a) is provided in the center of the top surface of the fixed seat (102). The first-level slot at the bottom of the stepped hole matches the rod part of the pull shaft. The cross-section of the second-level slot of the stepped hole matches the upper shape of the pull shaft. The depth of the second-level slot is greater than the thickness of the upper part of the pull shaft, so that the pull shaft can move up and down within the working range. The bottom of the double-tapered mandrel is embedded in the third-level slot of the stepped hole, and the bottom of the double-tapered mandrel is fixedly connected to the wall of the third-level slot.

9. The high-precision double-tensioning machine clamp for long inner hole sleeves according to claim 1, characterized in that, The upper part of the central through hole of the rising sleeve (6) is provided with a tapered hole (61), and a first snap-fit ​​part (62) for snapping the top of the double-tapered mandrel is provided on the lower side wall of the central through hole of the rising sleeve; a second snap-fit ​​part (23) that cooperates with the first snap-fit ​​part is provided on the top of the double-tapered mandrel, and a support part (24) for supporting the bottom of the rising sleeve is provided on the lower side of the second snap-fit ​​part; the bottom of the central through hole of the rising sleeve is radially expanded to form a support hole (63) for snapping the support part.

10. The high-precision double-tensioning machine clamp for long inner hole sleeves according to claim 1, characterized in that, A spacer (10) is fitted on the upper part of the double taper mandrel. A third through hole is provided on the spacer for the double taper mandrel (2) to pass through. The spacer is located between the upper sleeve and the lower sleeve.

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