Pneumatic back-pulling type internal expansion clamp

Abstract

The utility model discloses a pneumatic back-pulling type internal expansion clamp which comprises a four-shaft main body, a pull rod is installed on the four-shaft main body in a sliding mode, one end of the pull rod is connected with a telescopic air cylinder, the other end of the pull rod is in threaded connection with a connecting nut, and a flange base is installed on the four-shaft main body. The coupling nut is in sliding fit with the flange base; a chuck base is installed on the flange base, the coupling nut penetrates through the chuck base in a sliding mode, and a conical boss penetrating through the coupling nut is fixed to the chuck base. An internal expansion spring chuck arranged on the conical boss in a sleeving manner is clamped in the connecting nut; a positioning seat for limiting the connecting nut is mounted on the chuck base; the problems that an existing clamp is concentrated in internal supporting force, and deformation is generated when a thin-wall part with a large supporting inner hole diameter is machined are solved.

Description

Technical Field

[0001] This utility model relates to the field of tooling and fixture technology, and in particular to a pneumatic pull-back internal expansion clamp. Background Technology

[0002] Bicycle planetary carriers are hollow, thin-walled parts. During the machining of the outer circumference, positioning is achieved through an internal hole, typically supported by an internal support fixture. However, in traditional internal support fixtures, pulling an internal tie causes the tie's conical surface to expand conically with the fixture's conical surface, generating internal support force. This conical force is mainly concentrated at the head of the chuck, meaning the stress point is primarily at the contact point between the fixture head and the part. This uneven and concentrated internal support force can easily cause deformation, especially in parts with soft or thin-walled internal supports. This is particularly problematic when clamping parts with large inner diameters and high cutting forces during rough milling, leading to insufficient and overly concentrated internal support force and unstable clamping. Utility Model Content

[0003] The purpose of this utility model is to provide a pneumatic pull-back internal expansion clamp to solve the problem of deformation caused by the concentration of internal support force in existing clamps when machining thin-walled parts with large inner hole diameters.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] A pneumatic pull-back internal expansion clamp includes a four-axis main body. A pull rod is slidably mounted on the four-axis main body. One end of the pull rod is connected to a telescopic cylinder, and the other end of the pull rod is threaded to a connecting nut. A flange base is mounted on the four-axis main body, and the connecting nut is slidably engaged with the flange base. A chuck base is mounted on the flange base, and the connecting nut slides through the chuck base. A conical boss passing through the connecting nut is fixed on the chuck base. An internal expansion spring chuck sleeved on the conical boss is engaged inside the connecting nut. A positioning seat that limits the connection nut is mounted on the chuck base.

[0006] Preferably, the internal expansion spring collet includes a column and a conical hole formed on the column, the conical hole cooperating with the conical boss; the column is provided with a stepped structure extending into the connecting nut, the end of the stepped structure is provided with a plurality of circumferentially distributed limiting claws, the column is provided with a positioning surface and a positioning step; the column is provided with a plurality of circumferentially distributed first expansion grooves opening towards the positioning surface, and the column is provided with a plurality of circumferentially distributed second expansion grooves opening towards the limiting claws, the first expansion grooves and the second expansion grooves being staggered.

[0007] Preferably, there are 8 expansion grooves in both the first expansion groove and the second expansion groove.

[0008] Preferably, the connecting nut includes an integrally connected connecting part and a sliding part. The connecting part is provided with an internal threaded hole that mates with the thread of the pull rod. The sliding part includes four pull claws evenly distributed in the circumferential direction. The pull claws are provided with an inner ring groove for limiting the limiting claws.

[0009] Preferably, the chuck base has sliding holes evenly distributed circumferentially and located outside the conical boss, and the pull claw slides in engagement with the sliding holes.

[0010] Preferably, the flange base has a stepped hole, the sliding part slides in conjunction with the large hole of the stepped hole, and the connecting part slides in conjunction with the small hole of the stepped hole.

[0011] Preferably, the telescopic cylinder is a thin cylinder, and the thin cylinder is provided with a fastening threaded hole for connection with the pull rod.

[0012] Preferably, both ends of the pull rod are provided with threaded heads.

[0013] Beneficial effects:

[0014] The workpiece is positioned by surface contact using an internal expansion spring chuck. The internal expansion spring chuck and the conical boss have a conical surface fit. When the telescopic cylinder pulls the rod and the connecting nut moves, the internal expansion spring chuck is pressed against the conical boss and expands, thus supporting and clamping the inner wall of the workpiece to complete the positioning. Using an internal expansion spring chuck ensures the uniformity of the overall expansion size and guarantees support for the entire workpiece, avoiding the concentration of support force. For large-diameter thin-walled workpieces, stable processing can be carried out without deformation or damage after clamping. Attached Figure Description

[0015] Figure 1 This is a cross-sectional structural diagram of an embodiment of the present utility model;

[0016] Figure 2 This is a first-view perspective three-dimensional structural diagram of the internal expansion spring collet in an embodiment of this utility model;

[0017] Figure 3 This is a second-view perspective three-dimensional structural diagram of the internal expansion spring collet in an embodiment of this utility model;

[0018] Figure 4 This is a schematic diagram of the connecting nut in an embodiment of the present utility model;

[0019] Figure 5 This is a schematic diagram of the structure of the flange base mounting conical boss in an embodiment of this utility model;

[0020] Figure 6 This is a structural diagram illustrating the application state of an embodiment of the present utility model;

[0021] exist Figures 1 to 6 In the diagram, the correspondence between component names or lines and the drawing numbers is as follows:

[0022] Four-axis main body 1, tie rod 2, telescopic cylinder 3, connecting nut 4, connecting part 41, sliding part 42, internal threaded hole 43, pull claw 44, inner ring groove 45, flange base 5, stepped hole 51, chuck base 6, sliding hole 61, conical boss 7, internal expansion spring chuck 8, column 81, conical hole 82, stepped structure 83, limiting claw 84, positioning surface 85, positioning step 86, first expansion groove 87, second expansion groove 88, positioning seat 9. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0024] See Figures 1-6 As shown in the figure, an embodiment of this utility model proposes a pneumatic pull-back internal expansion clamp for internal expansion clamping and positioning of a bicycle planetary frame with a diameter of 64mm, facilitating machining of thin walls. Specifically, it includes a four-axis body 1, on which a pull rod 2 is slidably mounted. One end of the pull rod 2 is connected to a telescopic cylinder 3, and the other end of the pull rod 2 is threadedly connected to a connecting nut 4. A flange base 5 is mounted on the four-axis body 1, and the connecting nut 4 slides in conjunction with the flange base 5. By controlling the telescopic cylinder 3 to pull the pull rod 2, the connecting nut 4 slides relative to the flange base 5. Meanwhile, a chuck base 6 is installed on the flange base 5. The connecting nut 4 slides through the chuck base 6. A conical boss 7 passing through the connecting nut 4 is fixed on the chuck base 6. An internal expansion spring chuck 8 sleeved on the conical boss 7 is engaged inside the connecting nut 4. When the connecting nut 4 is pulled, causing the internal expansion spring chuck 8 to move towards the conical boss 7, its outer diameter expands. The workpiece placed on the internal expansion spring chuck 8 is supported and clamped. The inner hole of the internal expansion spring chuck 8 is a conical surface fit, while the outer surface fits the workpiece surface. Thus, after the internal expansion spring chuck 8 expands, it reliably clamps the workpiece, ensuring that the supporting force on the workpiece is evenly distributed and preventing concentrated stress on the workpiece, thus avoiding the risk of damage to the thin wall of the workpiece.

[0025] Meanwhile, a positioning seat 9 is installed on the chuck base 6 to limit the movement of the connecting nut 4. The positioning seat 9 and the flange base 5 limit the travel of the connecting nut 4, thereby preventing it from falling off.

[0026] In this embodiment, the internal expansion spring collet 8 can be replaced according to the different workpiece diameters, and each internal expansion spring collet 8 is suitable for supporting and clamping workpieces with a certain range of diameters. Specifically, the internal expansion spring collet 8 includes a column 81 and a conical hole 82 opened on the column 81. The conical hole 82 mates with the conical boss 7. At the same time, the column 81 is provided with a stepped structure 83 that extends into the connecting nut 4. The end of the stepped structure 83 is provided with a plurality of circumferentially distributed limiting claws 84. The column 81 is provided with a positioning surface 85 and a positioning step 86. The limiting claws 84 are limited by the connecting nut 4 and can pull the entire internal expansion spring collet 8 to move. The conical hole 82 and the conical boss 7 are in a conical surface fit, which can expand evenly during expansion. In order to achieve uniform expansion... The column 81 is provided with a plurality of first expansion grooves 87 that are evenly distributed circumferentially and open toward the positioning surface 85. The column 81 is also provided with a plurality of second expansion grooves 88 that are evenly distributed circumferentially and open toward the limiting claw 84. The first expansion grooves 87 and the second expansion grooves 88 are staggered. By setting the first expansion grooves 87 and the second expansion grooves 88 with opposite openings and staggered positions, it is ensured that the outer diameter of the entire positioning surface 85 increases uniformly when the size expands, so as to achieve surface contact with the workpiece and avoid the situation of concentrated supporting force on the workpiece. When the workpiece is fitted onto the positioning surface 85, it is positioned by the positioning step 86.

[0027] To further improve the uniformity of expansion size, the number of the first expansion groove 87 and the second expansion groove 88 are both 8.

[0028] The connecting nut 4 includes an integrally connected connecting part 41 and a sliding part 42. The connecting part 41 is provided with an internal threaded hole 43 that is threaded to the pull rod 2. The sliding part 42 includes four pull claws 44 evenly distributed in the circumferential direction. The pull claws 44 are provided with an inner ring groove 45 for limiting the limiting claw 84. The pull rod 2 is connected through the internal threaded hole 43, and the dispersed pull claws 44 can slide through the chuck base 6. The inner ring groove 45 engages with the limiting claw 84, allowing the inner expansion spring chuck 8 and the connecting nut 4 to move simultaneously.

[0029] Specifically, sliding holes 61 are evenly distributed circumferentially on the chuck base 6 and located on the outside of the conical boss 7. The pull claw 44 slides with the sliding holes 61, thereby guiding the entire connecting nut 4 to slide relative to the chuck base 6 and bearing load at intervals, thus improving structural stability.

[0030] Meanwhile, a stepped hole 51 is provided on the flange base 5. The sliding part 42 slides with the large hole of the stepped hole 51, and the connecting part 41 slides with the small hole of the stepped hole 51, so as to achieve positioning and guidance for the entire connecting nut 4 when it slides relative to the flange base 5.

[0031] The telescopic cylinder 3 is a thin-walled cylinder with a threaded hole for fastening and connecting to the pull rod 2. Using a thin-walled cylinder reduces the size of the tooling. Both ends of the pull rod 2 are threaded, and both ends are threaded for easy assembly and disassembly. The pull rod 2 undergoes heat treatment, resulting in good tensile strength.

[0032] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0033] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use. They are only for the convenience of describing this utility model and simplifying the description, and do 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. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0034] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A pneumatic rear-pull internal expansion clamp comprising a four-axis body (1), characterized in that: A pull rod (2) is slidably installed on the four-axis body (1), one end of the pull rod (2) is connected with a telescopic cylinder (3), the other end of the pull rod (2) is threadedly connected with a connecting nut (4), a flange base (5) is installed on the four-axis body (1), the connecting nut (4) and the flange base (5) are in sliding fit; A chuck base (6) is installed on the flange base (5), the connecting nut (4) slides through the chuck base (6), a conical boss (7) penetrating through the connecting nut (4) is fixed on the chuck base (6); An inner expansion spring chuck (8) is clamped in the connecting nut (4) and sleeved on the conical boss (7); A positioning seat (9) limiting the connecting nut (4) is installed on the chuck base (6).

2. A pneumatic rear-pull internal expansion fixture according to claim 1, characterized in that: The inner expansion spring chuck (8) comprises a column body (81) and a conical hole (82) formed in the column body (81), and the conical hole (82) is matched with the conical boss (7); A stepped structure (83) extending into the connecting nut (4) is arranged on the column body (81), and the end of the stepped structure (83) is provided with a plurality of limiting claws (84) uniformly distributed in the circumferential direction, and a positioning surface (85) and a positioning step (86) are arranged on the column body (81); A plurality of first expansion grooves (87) uniformly distributed in the circumferential direction and opening towards one side of the positioning surface (85) are arranged on the column body (81), and a plurality of second expansion grooves (88) uniformly distributed in the circumferential direction and opening towards one side of the limiting claw (84) are arranged on the column body (81), and the first expansion grooves (87) and the second expansion grooves (88) are arranged in a staggered manner.

3. A pneumatic rear-pull internal expansion fixture according to claim 2, wherein: The number of the first expansion grooves (87) and the second expansion grooves (88) is 8.

4. The pneumatic, rear-pull, internal-expansion clamp of claim 2, wherein: The connecting nut (4) comprises a connecting part (41) and a sliding part (42) connected integrally, the connecting part (41) is provided with an inner threaded hole (43) matched with the pull rod (2) in a threaded manner, the sliding part (42) comprises four pull claws (44) uniformly distributed in the circumferential direction, and the pull claw (44) is provided with an inner ring groove (45) for limiting the limiting claw (84).

5. A pneumatic rear-pull internal expansion fixture according to claim 4, wherein: A sliding hole (61) uniformly distributed in the circumferential direction and located outside the conical boss (7) is formed in the chuck base (6), and the pull claw (44) and the sliding hole (61) are in sliding fit.

6. A pneumatic rear-pull internal expansion fixture as claimed in claim 4, wherein: A stepped hole (51) is formed in the flange base (5), the sliding part (42) and the large hole of the stepped hole (51) are in sliding fit, and the connecting part (41) and the small hole of the stepped hole (51) are in sliding fit.

7. A pneumatic, rear-pull, inside-expanding clamp according to any one of claims 1-6, characterized in that: The telescopic cylinder (3) is a thin cylinder, and the thin cylinder is provided with a fastening threaded hole connected with the pull rod (2).

8. A pneumatic rear-pull internal expansion clamp according to claim 7, wherein: Threaded heads are arranged at both ends of the pull rod (2).

Images