A kind of long inside blind hole cylinder's expansion tool

Abstract

The utility model discloses a kind of expansion type tool for long inner blind hole cylinder barrel, to solve the problem of poor adaptability of existing tool single-point support, expansion sleeve stress cracking easily.It includes mandrel, lower expansion sleeve, sliding sleeve, taper sleeve, upper expansion sleeve, screw sleeve and guide rod;Lower expansion sleeve, upper expansion sleeve outer periphery is provided with axial expansion joint, and joint upper end is connected with larger diameter circular stress release hole;Guide rod passes through stress release hole and taper sleeve through-hole, and is fixed with mandrel screw hole, and outer end does not exceed expansion sleeve outer periphery.Working time, expansion oil cylinder drives mandrel to move up, taper section, taper sleeve synchronous support double expansion sleeve, realize cylinder barrel both ends expansion.The design eliminates expansion sleeve expansion stress concentration by stress release hole, and also prevents rotation through guide rod to strengthen expansion sleeve and taper sleeve linkage, improve positioning stability, adapt to long inner blind hole cylinder barrel, and expansion sleeve maintenance and replacement are convenient.

Description

Technical Field

[0001] This utility model relates to the field of auxiliary equipment for mechanical processing, specifically to a tensioning tool for a long internal blind hole cylinder, which is suitable for positioning and clamping in processes such as cylinder inner hole processing and surface treatment. Background Technology

[0002] In the field of machining, the machining accuracy of the cylinder barrel directly determines the reliability of the hydraulic cylinder. Existing technologies, such as the cylinder barrel internal bore tensioning positioning fixture disclosed in announcement number CN220591606U, utilize a "supporting" structure instead of two-pronged positioning by cooperating with a main bushing, a nylon expansion sleeve, a connecting shaft, and a linkage device. The connecting shaft moves axially along the main bushing, and the nylon expansion sleeve, fitted outside the connecting shaft, is compressed and deformed, then clamped onto the inner wall of the cylinder barrel, achieving cylinder barrel positioning. This effectively improves the machining accuracy of the cylinder head and the coaxiality at the cylinder port, while shortening machining steps and reducing production costs, making it suitable for machining rotary cylinder barrels. However, this internal tension positioning fixture still has significant limitations in practical applications: First, the fixture achieves positioning only through a single set of nylon expansion sleeves, with the tensioning effect concentrated in the middle area of ​​the cylinder bore, forming a "single-point support" structure. When machining long cylinders, the lack of effective positioning support at both ends of the cylinder makes it prone to vibration and deflection deformation during machining. Second, the single-point support positioning method has poor adaptability to cylinder length and can only meet the machining needs of shorter cylinders. For long cylinders exceeding 1000mm in length, the single-point tension in the middle cannot guarantee the overall coaxiality of the cylinder. Third, due to the force characteristics of single-point support, if the cutting amount needs to be increased to improve efficiency when machining long cylinders, the vibration amplitude of the cylinder will be further aggravated. This not only affects the surface roughness of the machined surface but may also cause the nylon expansion sleeves to wear prematurely due to excessive local stress, increasing the fixture maintenance cost and the rate of defective products. Utility Model Content

[0003] To overcome one or more of the technical defects in the existing technology, this utility model provides a tensioning tooling for a cylinder with a long internal blind hole. The technical solution adopted is as follows: A tensioning fixture for a long internal blind bore cylinder, comprising: The mandrel has a tapered section at its lower end with a maximum outer diameter smaller than the diameter of the cylinder blind bore, and the tapered section has a tapered structure that is larger at the bottom and smaller at the top; the mandrel has a threaded section above the cylinder bore, and the following are sequentially fitted along the axial direction of the mandrel from bottom to top: The lower expansion sleeve forms a tapered fit with the tapered section and is used to tighten the inner circumferential surface of the bottom of the blind hole in the long inner blind hole cylinder. The sliding sleeve is clearance-fitted with the spindle, and its lower end face abuts against the upper end face of the lower expansion sleeve; The tapered sleeve has a tapered structure that is larger at the bottom and smaller at the top. It forms a transition fit or clearance fit with the mandrel. Its lower end face abuts against the upper end face of the sliding sleeve and is positioned corresponding to the opening of the cylinder. An expanding sleeve is fitted onto the outer periphery of the tapered sleeve, forming an outer tapered fit with the tapered sleeve, and is used to tighten the inner circumferential surface of the opening of the long inner blind hole cylinder. A threaded sleeve is threaded to the threaded section, and the threaded sleeve is fixedly connected to the body of the processing equipment; The upper end of the mandrel is connected to a tensioning cylinder. When the tensioning cylinder drives the mandrel to move upward axially, the tapered section moves upward synchronously with the mandrel and radially expands the lower expansion sleeve. At the same time, the tapered sleeve moves upward synchronously with the mandrel and radially expands the upper expansion sleeve through the sliding sleeve, so that the lower expansion sleeve and the upper expansion sleeve simultaneously tension the bottom and opening of the blind hole of the long inner blind hole cylinder.

[0004] Furthermore, the axial height of the tapered sleeve and the tapered section are equal, and their tapered values ​​are the same.

[0005] Furthermore, the axial height of the lower expansion sleeve and the upper expansion sleeve are equal, and the inner taper of the lower expansion sleeve matches the outer taper of the taper segment, the inner taper of the upper expansion sleeve matches the outer taper of the taper sleeve, and the inner taper values ​​of the lower expansion sleeve and the upper expansion sleeve are the same.

[0006] Furthermore, both the lower expansion sleeve and the upper expansion sleeve have annular shoulders at their upper inner holes; the upper outer circumferential surface of the tapered section has annular stepped surfaces; and it also includes two springs, one of which has its lower end abutting against the stepped surface and its upper end abutting against the annular shoulder of the lower expansion sleeve, and the other spring has its lower end abutting against the upper end surface of the tapered sleeve and its upper end abutting against the annular shoulder of the upper expansion sleeve.

[0007] Furthermore, both the lower expansion sleeve and the upper expansion sleeve have multiple axial expansion slots on their outer peripheral surfaces. The axial expansion slots are evenly distributed along the circumference of the expansion sleeve, and the upper end of the axial expansion slot does not penetrate the upper end surface of the expansion sleeve.

[0008] Furthermore, each of the axial expansion joints has a circular stress relief hole at its upper end. The diameter of the circular stress relief hole is larger than the width of the axial expansion joint, and the circular stress relief hole is connected to the axial expansion joint. Corresponding to at least one circular stress relief hole of the lower expansion sleeve and the upper expansion sleeve, a screw hole is radially opened at the corresponding position of the mandrel. It also includes a guide rod, which passes through the circular stress relief hole and the through hole on the tapered sleeve and is screwed and fixed to the screw hole. The outer end face of the guide rod does not extend beyond the outer circumferential surface of the lower expansion sleeve or the upper expansion sleeve.

[0009] Furthermore, corresponding to at least one axial expansion joint of the lower expansion sleeve and the upper expansion sleeve, a screw hole is radially provided at the corresponding position of the mandrel; it also includes a guide rod, which passes through the axial expansion joint and is screwed and fixed to the screw hole, and the outer end face of the guide rod does not extend beyond the outer circumferential surface of the lower expansion sleeve or the upper expansion sleeve.

[0010] Furthermore, the outer end of the guide rod is provided with an internal hexagonal hole, or the outer peripheral surface of the guide rod near the outer end is provided with a non-circular torsion surface of a square or hexagonal prism.

[0011] Furthermore, the outer circumferential surface of the threaded sleeve is provided with a plurality of lower torsion holes for inserting tools, and the lower torsion holes are evenly distributed along the circumferential direction of the threaded sleeve.

[0012] Furthermore, the outer circumferential surface of the mandrel located above the threaded section has a plurality of upper torsion holes for inserting tools, which are evenly distributed along the circumferential direction of the mandrel.

[0013] The beneficial technical effects of this utility model are as follows: 1. Solve the problem of double-end positioning of long cylinder barrels and improve coaxiality accuracy. To address the limitation of existing tooling where "single-point support is only suitable for short cylinders," this tooling utilizes a dual-end synchronous tensioning structure consisting of a "lower expansion sleeve (bottom of the blind hole) + an upper expansion sleeve (mouth)" to achieve centering support across the entire length of long internal blind hole cylinders (1000-2000mm). The tapered fit between the tapered section and the lower expansion sleeve, as well as the tapered sleeve and the upper expansion sleeve, ensures that the tensioning force is evenly applied to the inner circumferential surfaces at both ends of the cylinder. This prevents deflection and vibration caused by the lack of support at both ends during the machining of long cylinders. The coaxiality error between the bottom and mouth of the blind hole can be controlled within 0.02mm, significantly superior to existing single-point support tooling (where the coaxiality error is typically >0.05mm), thus meeting the high-precision machining requirements of long cylinders.

[0014] 2. The tensioning force is synchronously controllable, extending the service life of the tooling. When the mandrel moves upward, the force is synchronously transmitted to the lower and upper expansion sleeves via the sliding sleeve. Combined with the tapered matching design of the "tapered section-lower expansion sleeve" and "tapered sleeve-upper expansion sleeve," this ensures consistent tension force at both ends and synchronized action, preventing localized overload. Compared to existing single-point support fixtures where the expansion sleeve is prone to wear due to excessive localized force, this fixture's expansion sleeve experiences more uniform force distribution, extending its service life. Furthermore, the structure, where the threaded sleeve is fixed to the processing equipment and the mandrel is connected to the tensioning cylinder, allows for precise adjustment of the tension force through cylinder pressure, adapting to cylinders of different wall thicknesses and preventing damage to thin-walled cylinders and insecure clamping of thick-walled cylinders.

[0015] 3. Automatic reset facilitates part removal and improves processing efficiency. The lower and upper sleeves, with their annular shoulders and spring structures, automatically push the lower and upper sleeves back along the tapered surface when the tensioning cylinder depressurizes and the mandrel resets. This allows for clamping and loosening without manual intervention, significantly reducing cylinder loading and unloading time. Furthermore, the spring's preload prevents the sleeves from loosening or shifting when not in operation, ensuring the tooling's repeatability and positioning accuracy.

[0016] 4. Optimize the stability of the expansion sleeve structure and reduce maintenance costs. The axial expansion joint between the lower and upper expansion sleeves provides ample deformation space for the radial expansion of the expansion sleeve, preventing cracking due to excessive rigidity. The circular stress relief hole at the upper end of the expansion joint eliminates stress concentration during expansion, further reducing the risk of breakage. Simultaneously, the guide rod, fixed to the mandrel via a screw hole and passing through the expansion joint / stress relief hole, restricts the circumferential rotation of the expansion sleeve (preventing it from rotating with the cylinder during machining) and allows for individual disassembly and replacement after wear, eliminating the need for complete tooling replacement and reducing maintenance costs.

[0017] 5. Highly adaptable and easy to operate, compatible with processing in multiple scenarios. The design of the lower torsion hole of the threaded sleeve and the upper torsion hole of the mandrel allows for quick adjustment of the relative position of the threaded sleeve and the mandrel using tools such as wrenches, adapting to cylinder barrels with long internal blind holes of different depths. By replacing the lower expansion sleeve and the upper expansion sleeve with different inner diameter specifications, there is no need to replace the mandrel and the tapered sleeve, which can be compatible with a wide range of cylinder barrel inner diameters. It meets the needs of internal hole machining, external turning, and surface chrome plating of various types of long internal blind hole cylinder barrels such as hydraulic support jack cylinder barrels and engineering machinery cylinder barrels. Its versatility is significantly better than that of existing special tooling. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model.

[0019] Figure 2 for Figure 1 Partial diagram.

[0020] Figure 3 for Figure 1 A sectional view. Detailed Implementation

[0021] In the description of this utility model, it should be noted that the terms "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the paper. This orientation or positional relationship is only for the convenience of describing this utility model and simplifying the description, and does not 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 this utility model.

[0022] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "communication" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0023] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0024] like Figure 1-3 The illustrated tensioning fixture for a long internal blind bore cylinder includes... The mandrel 1 has a tapered section 11 at its lower end, the maximum outer diameter of which is smaller than the diameter of the blind hole of the cylinder 100. The tapered section 11 has a tapered structure that is larger at the bottom and smaller at the top. A threaded section 12 is provided on the mandrel 1 above the opening of the cylinder 100, and the following are sequentially fitted along the axial direction of the mandrel 1 from bottom to top: The lower expansion sleeve 2 forms a tapered fit with the tapered section 11 and is used to tighten the inner circumferential surface of the bottom of the blind hole of the long inner blind hole cylinder 100; The sliding sleeve 3 is clearance-fitted with the spindle 1, and its lower end face abuts against the upper end face of the lower expansion sleeve 2; The tapered sleeve 4 has a tapered structure that is larger at the bottom and smaller at the top. It forms a transition fit or clearance fit with the spindle 1. Its lower end face abuts against the upper end face of the sliding sleeve 3 and is provided corresponding to the opening of the cylinder 100. The rising sleeve 6 is fitted around the outer periphery of the tapered sleeve 4 and forms an outer tapered fit with the tapered sleeve 4, used to tighten the inner circumferential surface of the opening of the long inner blind hole cylinder 100; The threaded sleeve 5 is screwed to the threaded section 12, and the threaded sleeve 5 is fixedly connected to the body of the processing equipment; The upper end of the mandrel 1 is connected to a tensioning cylinder. When the tensioning cylinder drives the mandrel 1 to move upward axially, the tapered section 11 moves upward synchronously with the mandrel 1 and radially expands the lower expansion sleeve 2. At the same time, the tapered sleeve 4 moves upward synchronously with the mandrel 1 and transmits force through the sliding sleeve 3 to radially expand the upper expansion sleeve 6, so that the lower expansion sleeve 2 and the upper expansion sleeve 6 simultaneously tension the bottom and opening of the blind hole of the long inner blind hole cylinder 100.

[0025] I. Working principle of this embodiment This tooling is based on the core mechanism of "tapered fit radial expansion + synchronous axial force transmission" to achieve synchronous tensioning and positioning of the long internal blind hole cylinder at both ends. The specific principle is as follows: Reference fixing and power transmission: The screw sleeve is fixed to the machine body of the processing equipment as the positioning reference of the tooling as a whole; the upper end of the mandrel is connected to the tensioning cylinder for transmission, and the cylinder provides axial driving force to drive the mandrel to move up and down along the axial direction.

[0026] Double-ended tapered expansion mechanism: The tapered section (larger at the bottom and smaller at the top) at the lower end of the mandrel forms a tapered fit with the lower expansion sleeve. When the mandrel moves upward, the tapered surface of the tapered section presses against the inner wall of the lower expansion sleeve, causing the lower expansion sleeve to expand radially, thereby tightening the inner circumferential surface at the bottom of the blind hole of the cylinder. The mandrel and the tapered sleeve are in transition / clearance fit. When the mandrel moves upward, it drives the tapered sleeve to move upward simultaneously. The lower end of the tapered sleeve abuts against the lower expansion sleeve through a sliding sleeve (which has a clearance fit with the mandrel and only transmits axial force). The tapered sleeve (larger at the bottom and smaller at the top) forms an outer tapered fit with the expansion sleeve. When the tapered sleeve moves upward, its tapered surface presses against the inner wall of the expansion sleeve, causing the expansion sleeve to expand radially and tighten the inner circumferential surface of the cylinder opening. Synchronization Guarantee: The axial abutment structure of the sliding sleeve synchronizes the displacement of the tapered sleeve and the lower expansion sleeve. Combined with the tapered design of the tapered section and the tapered sleeve, it ensures that the radial expansion action of the lower expansion sleeve and the upper expansion sleeve are consistent with the magnitude of the tensioning force, avoiding imbalance of force on one end.

[0027] II. The tensioning process in this embodiment Based on the tooling structure and processing scenario, the complete working process is divided into four steps: "material loading - tensioning - processing - clamping and part removal", as detailed below: Material loading preparation (initial state): The tensioning cylinder is in a depressurized state, the mandrel is in a low position, and the lower expansion sleeve and the upper expansion sleeve are not expanded (the inner diameter of the lower expansion sleeve is adapted to the small end of the tapered section, and the inner diameter of the upper expansion sleeve is adapted to the small end of the tapered sleeve); the long inner blind hole cylinder to be processed is placed on the outside of the tooling, so that the lower expansion sleeve extends into the bottom of the cylinder blind hole (the maximum outer diameter of the tapered section is smaller than the diameter of the cylinder blind hole to ensure smooth insertion), the upper expansion sleeve corresponds to the cylinder opening, and the lower end of the cylinder is placed on the support platform of the processing equipment.

[0028] Simultaneous tightening at both ends: When the tensioning cylinder is activated, the piston rod of the cylinder pulls the spindle upward, causing it to move axially upward. The mandrel drives the tapered section to move upward, the tapered section squeezes the inner wall of the lower expansion sleeve, the lower expansion sleeve expands radially until it is tightly fitted with the inner circumferential surface of the bottom of the cylinder blind hole, thus completing the bottom tightening; The mandrel synchronously drives the tapered sleeve to move upward. The tapered sleeve transmits axial force through the sliding sleeve (the sliding sleeve has no radial displacement, but moves axially synchronously with the tapered sleeve and the lower expansion sleeve). At the same time, the tapered sleeve squeezes the inner wall of the expansion sleeve, and the expansion sleeve expands radially until it is tightly fitted with the inner circumferential surface of the cylinder opening, thus completing the opening tension. At this point, the cylinder is centered and positioned by double-end tensioning, and can then proceed to machining processes (such as internal hole turning, surface treatment, etc.).

[0029] Processing stage: During the machining process, the screw sleeve is fixed to the tooling reference, and the lower expansion sleeve and the upper expansion sleeve tighten the two ends of the cylinder respectively to limit the radial movement and axial displacement of the cylinder, avoid the long cylinder from deflection or vibration due to lack of support, and ensure machining accuracy.

[0030] Release clamp and pick up part: After processing, the tensioning cylinder is depressurized, the mandrel loses its upward tension and resets (this can be achieved by reverse oil supply to the cylinder or by the tooling's own spring – the springs at the upper ends of the lower and upper sleeves are compressed during tensioning and elastically reset after depressurization, pushing the lower and upper sleeves back along the tapered surface). The mandrel moves downward, the tapered section is released from the compression of the lower expansion sleeve, the lower expansion sleeve contracts radially and separates from the bottom of the cylinder blind hole; The spindle synchronously drives the tapered sleeve to move downward, the tapered sleeve is released from the compression of the rising sleeve, the rising sleeve contracts radially and separates from the cylinder opening; Finally, either manually or with a robotic arm, the cylinder is removed from the outside of the tooling, completing a single processing cycle.

[0031] In another preferred embodiment, the axial height of the tapered sleeve 4 and the tapered segment 11 are equal, and their taper values ​​are the same. By making the axial height and taper value of the tapered sleeve and the tapered segment completely consistent, the conical surface contact characteristics of the two are ensured to be the same when the mandrel is displaced. This achieves synchronization of the radial expansion of the lower expansion sleeve and the upper expansion sleeve, effectively reducing the imbalance of the double-end tensioning force caused by differences in structural parameters, and significantly improving the coaxiality accuracy of the long cylinder positioning.

[0032] In another preferred embodiment, the lower expansion sleeve 2 and the upper expansion sleeve 6 have the same axial height, and the inner taper of the lower expansion sleeve 2 matches the outer taper of the taper segment 11, while the inner taper of the upper expansion sleeve 6 matches the outer taper of the taper sleeve 4. The inner taper values ​​of the lower expansion sleeve 2 and the upper expansion sleeve 6 are the same. The equal axial height of the lower expansion sleeve and the upper expansion sleeve, along with their precise matching of the inner tapers to the taper segment and the taper sleeve, ensures a uniform distribution of contact stress between the expansion sleeve and the taper component, preventing premature wear caused by localized stress concentration. Simultaneously, it ensures consistent tension force at both ends, further suppressing bending deformation during the machining of long cylinders.

[0033] In another preferred embodiment, annular shoulders are formed at the upper inner holes of both the lower expansion sleeve 2 and the upper expansion sleeve 6; annular stepped surfaces 111 are formed on the upper outer circumferential surface of the tapered section 11; and two springs 7 are also included, one of which has its lower end abutting against the stepped surface 111 and its upper end abutting against the annular shoulder of the lower expansion sleeve 2, and the other spring 7 has its lower end abutting against the upper end face of the tapered sleeve 4 and its upper end abutting against the annular shoulder of the upper expansion sleeve 6. The elastic pre-tightening structure of the annular shoulder and the stepped surface, combined with the springs, allows the lower expansion sleeve and the upper expansion sleeve to automatically retract and retract along the tapered surface after the tensioning cylinder is depressurized, achieving rapid release without manual intervention and significantly shortening the part removal time; the stable support of the springs also prevents the expansion sleeves from loosening or shifting when not in operation, ensuring repeatability and positioning accuracy.

[0034] In another preferred embodiment, both the lower expansion sleeve 2 and the upper expansion sleeve 6 have multiple axial expansion slots 26 on their outer peripheral surfaces. These axial expansion slots 26 are evenly distributed along the circumference of the expansion sleeve, and their upper ends do not penetrate the upper surface of the expansion sleeve. The evenly distributed axial expansion slots on the outer periphery of the expansion sleeve provide sufficient deformation space for radial expansion, ensuring a tight fit between the expansion sleeve and the inner wall of the cylinder and uniform stress distribution. The design that the upper ends of the expansion slots do not penetrate preserves the integrity of the main structure of the expansion sleeve, preventing breakage due to insufficient rigidity during expansion and extending its service life.

[0035] In another preferred embodiment, each of the axial expansion joints 26 has a circular stress relief hole 62 at its upper end. The diameter of the circular stress relief hole 62 is larger than the width of the axial expansion joint 26, and the circular stress relief hole 62 communicates with the axial expansion joint 26. Corresponding to at least one circular stress relief hole 62 of the lower expansion sleeve 2 and the upper expansion sleeve 6, a screw hole 13 is radially opened at the corresponding position of the mandrel 1. A guide rod 8 is also included, which passes through the circular stress relief hole 62 and the through hole 41 on the tapered sleeve 4 and is screwed to the screw hole 13 for fixation. The outer end face of the guide rod 8 does not extend beyond the outer circumferential surface of the lower expansion sleeve 2 or the upper expansion sleeve 6. The circular stress relief hole eliminates stress concentration by increasing the radius of curvature at the end of the expansion joint (reducing the stress concentration coefficient by more than 40%). Combined with the guide rod passing through the hole and the mandrel fixing structure, this not only restricts the circumferential rotation of the expansion sleeve to prevent rotation during processing, but also allows for quick positioning of the expansion sleeve via the guide rod, facilitating individual replacement of the expansion sleeve after wear and reducing maintenance costs.

[0036] In another preferred embodiment, corresponding to at least one axial expansion joint 26 of the lower expansion sleeve 2 and the upper expansion sleeve 6, a screw hole 13 is radially provided at the corresponding position of the mandrel 1; it also includes a guide rod 8, which passes through the axial expansion joint 26 and is screwed to the screw hole 13 for fixation, and the outer end face of the guide rod 8 does not exceed the outer circumferential surface of the lower expansion sleeve 2 or the upper expansion sleeve 6. The design of the guide rod passing through the axial expansion joint and being screwed to the mandrel effectively limits the circumferential displacement of the expansion sleeve without affecting the radial expansion flexibility of the expansion sleeve, ensuring positioning stability; this structure is particularly suitable for the anti-rotation requirements of large-diameter expansion sleeves and simplifies the tooling assembly process.

[0037] In another preferred embodiment, the outer end of the guide rod 8 is provided with an internal hexagonal hole, or the outer circumferential surface of the guide rod 8 near the outer end is provided with a non-circular torsion surface of a square or hexagonal prism. The guide rod structure with an internal hexagonal hole or a non-circular torsion surface allows for quick assembly and disassembly using standard tools, avoiding slippage during guide rod installation and removal, improving the efficiency of sleeve replacement and maintenance, and ensuring the consistency of the guide rod's fixing torque.

[0038] In another preferred embodiment, the outer circumferential surface of the threaded sleeve 5 is provided with a plurality of lower torsion holes 51 for inserting tools, which are evenly distributed along the circumference of the threaded sleeve 5. The evenly distributed lower torsion holes on the outer circumference provide a reliable tool application point for the threaded sleeve, facilitating quick adjustment of the relative position between the threaded sleeve and the mandrel using tools such as wrenches. This easily adapts to the positioning requirements of blind hole cylinders of different depths, significantly improving the versatility and adjustment efficiency of the tooling.

[0039] In another preferred embodiment, the outer circumferential surface of the mandrel 1 above the threaded section 12 is provided with a plurality of upper torsion holes 14 for inserting tools, which are evenly distributed along the circumference of the mandrel 1. The upper torsion hole design above the threaded section can be used with tools to fix the position of the mandrel, facilitate the tightening and loosening of the threaded sleeve, ensure the accuracy of the relative position adjustment between the mandrel and the threaded sleeve, and effectively improve the convenience of operation, especially in tooling assembly and maintenance, and ensure the stability of the positioning reference.

[0040] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A tensioning fixture for a long internal blind bore cylinder, characterized in that, include The mandrel (1) has a tapered section (11) at its lower end with a maximum outer diameter smaller than the diameter of the blind hole of the cylinder (100). The tapered section (11) has a tapered structure that is larger at the bottom and smaller at the top. A threaded section (12) is provided on the mandrel (1) above the opening of the cylinder (100), and the following are sequentially fitted along the axial direction of the mandrel (1) from bottom to top: The lower expansion sleeve (2) forms a tapered fit with the tapered section (11) and is used to tighten the inner circumferential surface of the bottom of the blind hole of the long inner blind hole cylinder (100); The sliding sleeve (3) is in clearance fit with the spindle (1), and its lower end face abuts against the upper end face of the lower expansion sleeve (2); The tapered sleeve (4) has a tapered structure with a larger bottom and a smaller top, and forms a transition fit or clearance fit with the spindle (1). Its lower end face abuts against the upper end face of the sliding sleeve (3), and is set at the opening of the cylinder (100). The rising sleeve (6) is fitted around the outer periphery of the tapered sleeve (4) and forms an outer tapered fit with the tapered sleeve (4) to tighten the inner circumferential surface of the opening of the long inner blind hole cylinder (100); The threaded sleeve (5) is screwed to the threaded section (12), and the threaded sleeve (5) is fixedly connected to the body of the processing equipment; The upper end of the mandrel (1) is connected to a tensioning cylinder. When the tensioning cylinder drives the mandrel (1) to move upward axially, the tapered section (11) moves upward synchronously with the mandrel (1) and radially expands the lower expansion sleeve (2). At the same time, the tapered sleeve (4) moves upward synchronously with the mandrel (1) and transmits force through the sliding sleeve (3) to radially expand the upper expansion sleeve (6), so that the lower expansion sleeve (2) and the upper expansion sleeve (6) simultaneously tighten the bottom and opening of the blind hole of the long inner blind hole cylinder (100).

2. The tensioning fixture for a long internal blind bore cylinder according to claim 1, characterized in that, The tapered sleeve (4) and the tapered section (11) have the same axial height and the same taper value.

3. The tensioning fixture for a long internal blind bore cylinder according to claim 2, characterized in that, The axial height of the lower expansion sleeve (2) and the upper expansion sleeve (6) are equal, and the inner taper of the lower expansion sleeve (2) matches the outer taper of the taper segment (11), the inner taper of the upper expansion sleeve (6) matches the outer taper of the taper sleeve (4), and the inner taper values ​​of the lower expansion sleeve (2) and the upper expansion sleeve (6) are the same.

4. The tensioning fixture for a long internal blind bore cylinder according to claim 1, characterized in that, Both the lower expansion sleeve (2) and the upper expansion sleeve (6) have annular shoulders at their upper inner holes; the upper outer circumferential surface of the tapered section (11) is provided with annular step surface (111); it also includes two springs (7), one of which has its lower end abutting against the step surface (111) and its upper end abutting against the annular shoulder of the lower expansion sleeve (2), and the other spring (7) has its lower end abutting against the upper end surface of the tapered sleeve (4) and its upper end abutting against the annular shoulder of the upper expansion sleeve (6).

5. The tensioning fixture for a long internal blind bore cylinder according to claim 1, characterized in that, The outer circumferential surfaces of the lower expansion sleeve (2) and the upper expansion sleeve (6) are provided with multiple axial expansion slots (26). The axial expansion slots (26) are evenly distributed along the circumferential direction of the expansion sleeve, and the upper end of the axial expansion slots (26) does not penetrate the upper end surface of the expansion sleeve.

6. The tensioning fixture for a long internal blind bore cylinder according to claim 5, characterized in that, The upper end of each axial expansion joint (26) is provided with a circular stress relief hole (62). The diameter of the circular stress relief hole (62) is larger than the width of the axial expansion joint (26), and the circular stress relief hole (62) is connected to the axial expansion joint (26). Corresponding to at least one circular stress relief hole (62) of the lower expansion sleeve (2) and the upper expansion sleeve (6), the corresponding position of the mandrel (1) is provided with a screw hole (13) in the radial direction. It also includes a guide rod (8). The guide rod (8) passes through the circular stress relief hole (62) and the through hole (41) on the tapered sleeve (4) and is screwed to the screw hole (13). The outer end face of the guide rod (8) does not exceed the outer circumferential surface of the lower expansion sleeve (2) or the upper expansion sleeve (6).

7. The tensioning fixture for a long internal blind bore cylinder according to claim 5, characterized in that, For at least one axial expansion joint (26) corresponding to the lower expansion sleeve (2) and the upper expansion sleeve (6), the mandrel (1) is provided with a screw hole (13) radially at the corresponding position; it also includes a guide rod (8), which passes through the axial expansion joint (26) and is screwed to the screw hole (13), and the outer end face of the guide rod (8) does not exceed the outer circumferential surface of the lower expansion sleeve (2) or the upper expansion sleeve (6).

8. The tensioning fixture for a long internal blind bore cylinder according to claim 7, characterized in that, The outer end of the guide rod (8) is provided with an internal hexagonal hole, or the outer circumferential surface of the guide rod (8) near the outer end is provided with a non-circular torsion surface of a square or hexagonal prism.

9. The tensioning fixture for a long internal blind bore cylinder according to claim 1, characterized in that, The outer circumferential surface of the threaded sleeve (5) is provided with a plurality of lower torsion holes (51) for inserting tools, and the lower torsion holes (51) are evenly distributed along the circumferential direction of the threaded sleeve (5).

10. The tensioning fixture for a long internal blind bore cylinder according to claim 1, characterized in that, The outer circumferential surface of the mandrel (1) located above the threaded section (12) has a plurality of upper torsion holes (14) for inserting tools, which are radially provided. The upper torsion holes (14) are evenly distributed along the circumferential direction of the mandrel (1).

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