An expansion sleeve with self-cleaning function

Abstract

This invention relates to the field of workpiece airtightness testing, and provides an expansion sleeve with a self-cleaning function for airtightness testing of workpieces. It includes: a support shaft with a first airflow channel; a fixed base with a mounting cavity and a second airflow channel; multiple clamping blocks disposed within the mounting cavity, having a clamping state where they are close to each other and a released state where they are far apart; and a testing element disposed within the mounting cavity, having a third airflow channel. In the released state, the first and second airflow channels are connected, and gas flows through the first and second airflow channels to the gaps between the clamping blocks to purge them. In the clamping state, the first and second airflow channels are disconnected, and gas flows through the first and third airflow channels to the workpiece for airtightness testing. This design achieves automatic switching between a "cleaning air path" and a "testing air path."

Description

Technical Field

[0001] This invention belongs to the field of workpiece airtightness testing, and specifically relates to an expansion sleeve with self-cleaning function. Background Technology

[0002] In the fields of machining and automated inspection, airtightness testing is a critical process for ensuring the quality of workpieces (such as engine blocks, pump and valve housings, etc.). To achieve efficient and accurate testing, specialized fixtures or expansion sleeves are typically used to secure the workpiece and simultaneously perform sealing and inflation testing. Existing airtightness testing expansion sleeves usually include a support structure, movable clamping blocks, and an airflow channel for introducing the testing gas.

[0003] However, in existing expansion sleeves, when the workpiece is released (i.e., loosened), the multiple clamping blocks move away from each other, creating noticeable gaps between adjacent clamping blocks. While this structure meets the space requirements for workpiece loading and unloading, it poses serious safety hazards in industrial production environments. Production sites are often accompanied by large amounts of metal processing debris, dust, and other contaminants, which can easily fall into these gaps and accumulate on the inner surface of the clamping blocks or in sliding contact areas.

[0004] Due to the lack of effective cleaning methods, these accumulated metal shavings and dust will hinder the tight fit between adjacent clamping blocks during the next clamping action of the expansion sleeve. Specifically, the presence of impurities can cause the clamping blocks to fail to fully reset or to develop slight misalignments, resulting in uneven distribution of clamping force and an inability to form a stable, concentric grip on the workpiece. This not only reduces the stability of the clamping, but more seriously, the instability of the clamping state directly leads to unreliable sealing effects, thereby affecting the accuracy and repeatability of airtightness testing of the workpiece. It may even lead to the misjudgment of qualified products or the failure to detect unqualified products, reducing production efficiency and product quality. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, the technical problem this invention aims to solve is to provide a self-cleaning expansion sleeve. Through the axial movement of the support shaft, the first and second airflow channels can be connected or disconnected to adapt to different working states. When the clamping blocks are in the released state, the support shaft is in its initial position, and the first and second airflow channels are connected. Gas input from an external air source flows through the first and second airflow channels to the gaps between the clamping blocks, completing self-cleaning. When the clamping blocks are in the clamping state, the first and second airflow channels are disconnected, and gas flows through the first and third airflow channels to the inspection chamber inside the workpiece for airtightness testing.

[0006] The technical solution adopted by this invention to solve its technical problem is to propose an expansion sleeve with self-cleaning function for airtightness testing of workpieces, comprising: A support shaft having a first airflow channel inside, the support shaft having an interface for connecting an external air source; A fixed base has a mounting cavity and a second airflow channel inside, and one end of the support shaft is movably inserted into the mounting cavity; Multiple clamping blocks are movably disposed within the mounting cavity and are drively connected to the support shaft; each clamping block has a clamping state that is close to each other and a released state that is far from each other, and when in the released state, there is a gap between two adjacent clamping blocks; A detection element is movably disposed within the mounting cavity, with one end of the detection element being drively connected to the support shaft and the other end extending between each of the clamping blocks. The detection element is provided with a third airflow channel, which communicates with the first airflow channel. When in the released state, the first airflow channel is connected to the second airflow channel, and the gas in the first airflow channel flows through the second airflow channel to the gap between each clamping block to purge the gap between the clamping blocks. When in the clamping state, the first airflow channel is disconnected from the second airflow channel, and the gas in the first airflow channel flows to the workpiece through the third airflow channel for airtightness testing of the workpiece.

[0007] In the above-mentioned expansion sleeve with self-cleaning function, a movable block is also movably provided in the mounting cavity, and a first connecting through hole is provided in the movable block; one end of the support shaft is inserted into one end of the first connecting through hole, the end of the detection element away from the clamping block is inserted into the other end of the first connecting through hole, and the first airflow channel and the third airflow channel are connected through the first connecting through hole.

[0008] In the above-mentioned expansion sleeve with self-cleaning function, the inner wall of the mounting cavity is provided with a mounting groove communicating with the second airflow channel, the moving block is at least partially movable in the mounting groove, and the moving block is provided with a fourth airflow channel communicating with the first connecting through hole; When the clamping block is in the released state, the fourth airflow channel is connected to the mounting slot; When the clamping block is in the clamping state, the fourth airflow channel is disconnected from the mounting groove.

[0009] In the aforementioned expansion sleeve with self-cleaning function, the mounting groove includes a sealing section and a connecting section arranged sequentially along its axial direction, the inner diameter of the connecting section being larger than the inner diameter of the sealing section; a first sealing element and a second sealing element are embedded at intervals along the axial direction on the outer side wall of the movable block, the opening of the fourth airflow channel is located on the side wall of the movable block between the first sealing element and the second sealing element, the first sealing element slides against the inner wall of the sealing section, and the second sealing element has a first working position located within the connecting section and a second working position abutting against the inner wall of the sealing section.

[0010] In the aforementioned expansion sleeve with self-cleaning function, a connecting block is also movably disposed within the mounting cavity. One side of the connecting block is fixedly connected to the moving block, and the other side is connected to each of the clamping blocks. The moving block drives the clamping blocks to switch between the clamping state and the releasing state through the connecting block.

[0011] In the above-mentioned expansion sleeve with self-cleaning function, the opening end of the mounting cavity has a conical inner wall, and the outer walls of each clamping block together form a conical surface adapted to the conical inner wall, and the conical surface slides against the conical inner wall.

[0012] In the aforementioned expansion sleeve with self-cleaning function, the detection element includes a connecting part, an inner part, and an outer part arranged coaxially. The third airflow channel is disposed inside the inner part, and the outer part is sleeved outside the inner part. One end of the connecting part is inserted into the first connecting through hole of the moving block, and the connecting part is provided with a through second connecting through hole. One end of the inner part passes through the second connecting through hole, and one end of the outer part is inserted into the second connecting through hole.

[0013] In the aforementioned expansion sleeve with self-cleaning function, the outer sleeve has a through-hole, the end of the inner sleeve away from the connecting portion extends into the inner hole, and the inner hole communicates with the third airflow channel.

[0014] In the above-mentioned expansion sleeve with self-cleaning function, the outer sleeve is provided with a detection end at the end away from the moving block. The end face contour of the detection end is adapted to the bottom contour of the workpiece. When in the clamping state, the end face of the detection end abuts against the bottom of the workpiece to seal the position to be detected on the workpiece.

[0015] In the above-mentioned expansion sleeve with self-cleaning function, a fifth airflow channel is also provided in the side wall of the detection end. The air inlet end of the fifth airflow channel is connected to the third airflow channel, and the exhaust end of the fifth airflow channel extends to the end face of the detection end and forms a detection opening.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) This invention cleverly constructs a high-speed purging air path that directly reaches the gap between the clamping blocks by setting a movable block that can slide axially within the mounting slot of the fixed seat, and utilizing the cooperation of the first and second seals on the movable block with the sealing section and connecting section with varying inner diameter of the mounting slot. When the clamping block is released, the second seal enters the connecting section with a large inner diameter to form an airflow bypass gap. This design can actively and quickly purge metal debris and dust accumulated in the moving parts of the clamping block using high-pressure gas, avoiding problems such as inaccurate clamping block reset and uneven clamping force caused by impurity accumulation. This fundamentally ensures the concentricity and stability of subsequent workpiece clamping and significantly improves the repeatability and reliability of airtightness testing.

[0018] (2) By connecting the axial displacement of the support shaft with the valve core function of the moving block, a purely mechanical automatic switching between the "cleaning air path" and the "detection air path" is realized. This design does not require any external solenoid valves or sensors for control, and relies entirely on the mechanical action of the expansion sleeve itself, which greatly reduces the complexity and cost of the control system, eliminates the response delay caused by electrical control switching, makes the equipment switch between the cleaning and detection modes more quickly and reliably, and reduces potential failure points.

[0019] (3) By setting a conical inner wall at the opening end of the mounting cavity and making the conical surface formed by the outer sides of multiple clamping blocks slide against it; by utilizing the inclined wedge clamping principle, the axial linear driving force provided by the support shaft is efficiently converted into the centripetal radial extrusion force of each clamping block on the workpiece, and a normal positive pressure is generated at the contact interface, which achieves an extremely high force amplification ratio, ensuring that the clamping blocks can firmly clamp the workpiece, and effectively preventing the workpiece from axial movement or sealing failure under the high pressure environment of airtightness testing. Attached Figure Description

[0020] Figure 1 This is a 3D view of the proposed solution.

[0021] Figure 2 yes Figure 1 The floor plan.

[0022] Figure 3 yes Figure 2 Sectional view of AA.

[0023] Figure 4 yes Figure 1 A plan view of the hidden part of the structure.

[0024] Figure 5 yes Figure 4 A cross-sectional view of BB.

[0025] Figure 6This is a 3D view of the clamping block in this design.

[0026] Figure 7 This is a 3D view of the test piece in this scheme.

[0027] Figure 8 yes Figure 7 The floor plan.

[0028] Figure 9 yes Figure 8 A sectional view of CC.

[0029] In the figure, 100 is the support shaft; 110 is the first airflow channel; 200 is the fixed seat; 210 is the mounting cavity; 211 is the mounting groove; 211a is the sealing section; 211b is the connecting section; 212 is the conical inner wall; 220 is the second airflow channel; 300 is the clamping block; 310 is the second annular groove; 311 is the second flange; 320 is the conical surface; 400 is the detection element; 410 is the third airflow channel; 420 is the connecting part; 430 is the embedded part; 440 is the outer sleeve part; 441 is the embedded hole; 442 is the detection end; 443 is the fifth airflow channel; 443a is the detection opening; 500 is the moving block; 510 is the first connecting through hole; 520 is the fourth airflow channel; 530 is the first seal; 540 is the second seal; 600 is the connecting block; 610 is the first annular groove; 611 is the first flange. Detailed Implementation

[0030] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0031] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0032] like Figures 1 to 9As shown, this solution provides a self-cleaning expansion sleeve for airtightness testing of workpieces, comprising: a support shaft 100, which has a first airflow channel 110 and an interface for connecting to an external air source; a fixed seat 200, which is movably fitted with the support shaft 100, and has an installation cavity 210 and a second airflow channel 220; multiple clamping blocks 300, which are evenly distributed along the circumference of the installation cavity 210 and are drivenly connected to the support shaft 100; each clamping block 300 has a clamping state close to each other and a released state far apart from each other, and when in the released state, there is a gap between two adjacent clamping blocks 300; and a detection element 400, which is movably disposed in the installation cavity 210, with one end of the detection element 400 drivenly connected to the support shaft 100 and the other end extending between the clamping blocks 300, and the detection element 400 having a third airflow channel 410.

[0033] In this design, the expansion sleeve, through the axial movement of the support shaft 100, connects and disconnects the first airflow channel 110 and the second airflow channel 220, adapting to different working states. The specific switching logic is as follows: In the release state, the support shaft 100 is in its initial position. At this time, the first airflow channel 110 and the second airflow channel 220 are connected. Gas input from an external air source flows through the first airflow channel 110 and the second airflow channel 220, ultimately flowing into the gap between each clamping block 300 to complete self-cleaning. Simultaneously, the first connecting through hole 510 and the third airflow channel 410 are also connected, and the detection element 400 does not form a seal with the workpiece. Although gas flows out through the third airflow channel 410, it does not affect the cleaning effect of the gap between the clamping blocks 300. In the clamping state, the first airflow channel 110 and the second airflow channel 220 are disconnected. Gas flows through the first airflow channel 110 and the third airflow channel 410 into the inspection chamber inside the workpiece for airtightness testing.

[0034] The support shaft 100 is connected to the drive shaft on the machine tool and can move axially under the drive of the drive shaft. When in the clamping state, each clamping block 300 approaches each other, and their clamping ends together form a contouring structure that matches the outer contour of the workpiece. The contouring structure is tightly pressed against the outer contour of the workpiece to achieve stable clamping of the workpiece and maintain the sealing during inspection.

[0035] The working process of the expansion sleeve in this solution is as follows: In the initial working state, the clamping blocks 300 are in the released state, and the clamping blocks 300 are far apart from each other, forming a gap. The workpiece to be tested is placed between the clamping blocks 300. Then, the drive shaft of the machine tool drives the support shaft 100 to move relative to the fixed seat 200. Through the transmission connection between the support shaft 100 and the clamping blocks 300, the clamping blocks 300 are driven to move closer synchronously until they are pressed against each other. At this time, the contour structure of the clamping blocks 300 fits tightly with the outer contour of the workpiece, realizing the stable and concentric clamping of the workpiece, and providing a reliable seal for airtightness testing.

[0036] After the workpiece is clamped in place, the first airflow channel 110 is disconnected from the second airflow channel 220. An external air source is input through the interface on the support shaft 100. The gas flows through the first airflow channel 110 and the third airflow channel 410 to the inspection chamber inside the workpiece. The gas flow rate change is detected in real time by the flow meter integrated on the machine tool or testing system to determine whether there is a leak in the workpiece and thus whether the workpiece is qualified.

[0037] After the airtightness test is completed, the drive shaft on the machine tool drives the support shaft 100 to move in the opposite direction, causing each clamping block 300 to switch from the clamping state to the releasing state. The clamping blocks 300 move away from each other and re-form gaps, and the first airflow channel 110 and the second airflow channel 220 are connected. Then, the external air source supplies air again, and the gas flows through the first airflow channel 110 and the second airflow channel 220 to the gaps between each clamping block 300. Through the blowing action, any residual metal shavings, dust and other debris are blown away, completing the self-cleaning process.

[0038] Through an integrated structural design, workpiece clamping, airtightness testing, and self-cleaning functions are combined, solving the problem of dust accumulation between clamping blocks 300, which affects clamping accuracy and testing reliability. Specifically, the self-cleaning function effectively prevents metal shavings and dust from accumulating in the gaps between clamping blocks 300, ensuring that adjacent clamping blocks 300 can fit tightly together during the next clamping, with uniform clamping force distribution, achieving stable and concentric gripping of the workpiece. Stable clamping and reliable sealing prevent misjudgments and missed detections caused by loose clamping or poor sealing, ensuring the accuracy and repeatability of airtightness testing. The self-cleaning operation is connected to the testing process transmission, eliminating the need for manual cleaning, reducing auxiliary operation time, and lowering the probability of equipment failure due to debris accumulation, indirectly improving production efficiency and product quality.

[0039] Furthermore, a movable block 500 is also movably disposed within the mounting cavity 210, and the movable block 500 has a through first connecting hole 510. One end of the support shaft 100 is inserted into one end of the first connecting hole 510, and the end of the detection element 400 away from the clamping block 300 is inserted into the other end of the first connecting hole 510. The first airflow channel 110 and the third airflow channel 410 are connected through the first connecting hole 510. The support shaft 100 and the first connecting hole 510 can be fixed together by an interference fit, or they can be fixed together by external threads on the outer circumference of the support shaft 100 and internal threads in the first connecting hole 510.

[0040] Furthermore, the inner wall of the mounting cavity 210 is provided with a mounting groove 211 that communicates with the second airflow channel 220. The moving block 500 is at least partially movable within the mounting groove 211, and the moving block 500 is provided with a fourth airflow channel 520 that communicates with the first connecting through hole 510. In the released state, the fourth airflow channel 520 communicates with the mounting groove 211. In the clamping state, the fourth airflow channel 520 is disconnected from the mounting groove 211.

[0041] When the clamping block 300 is in the released state, the gas from the external air source enters the mounting cavity 210 through the first airflow channel 110, the first connecting through hole 510, the fourth airflow channel 520, the mounting groove 211, and the second airflow channel 220, and finally flows to the gap between each clamping block 300 to achieve self-cleaning. At the same time, the first airflow channel 110, the first connecting through hole 510, and the third airflow channel 410 are also in a connected state, and the detection element 400 does not form a seal with the workpiece. Although the gas flows out through the third airflow channel 410, it will not affect the cleaning effect of the gap between each clamping block 300.

[0042] When the clamping block 300 switches from the released state to the clamping state, the moving block 500 moves along the mounting groove 211 under the drive of the support shaft 100. The fourth airflow channel 520 is disconnected from the mounting groove 211 as the moving block 500 moves. At the same time, the first airflow channel 110, the first connecting through hole 510 and the third airflow channel 410 are connected. The workpiece is clamped by the clamping block 300. Then, the gas provided by the external gas source flows through the first airflow channel 110, the first connecting through hole 510 and the third airflow channel 410, and finally flows into the inspection chamber inside the workpiece to ensure that the gas is only used for airtightness testing.

[0043] The axial movement of the movable block 500 within the mounting groove 211 enables dynamic connection and disconnection between the fourth airflow channel 520 and the mounting groove 211. This mechanically driven airflow switching structure eliminates the need for additional solenoid valve control, relying entirely on the mechanical action of the expansion sleeve itself to achieve interlocked switching between "cleaning" and "detection" modes. This reduces the complexity of the control system and improves the equipment's response speed and reliability. Integrating the first connecting through-hole 510 and the fourth airflow channel 520 within the movable block 500 not only facilitates gas transmission but also utilizes the movable block 500 itself as the valve core for airflow switching. This integrated design of transmission and fluid control functions makes the entire expansion sleeve structure more compact, reduces external piping connections, lowers leakage points, and simplifies installation and maintenance.

[0044] Furthermore, the mounting groove 211 includes a sealing section 211a and a connecting section 211b arranged sequentially along its axial direction. The inner diameter of the connecting section 211b is larger than the inner diameter of the sealing section 211a, thereby forming a guide cone surface or a stepped surface at the junction of the two.

[0045] Two circumferentially arranged sealing grooves are formed on the outer wall of the movable block 500, and a first sealing element 530 and a second sealing element 540 are respectively embedded in the sealing grooves. The opening of the fourth airflow channel 520 is located on the side wall of the movable block 500 between the first sealing element 530 and the second sealing element 540; the first sealing element 530 slides against the inner wall of the sealing section 211a, and the second sealing element 540 has a first working position located in the connecting section 211b and a second working position against the inner wall of the sealing section 211a. The first sealing element 530 and the second sealing element 540 can both be O-rings or Y-rings, and the first sealing element 530 and the second sealing element 540 are not limited to rubber rings; they can also be polytetrafluoroethylene sealing rings, combined sealing rings, or a wear-resistant sealing coating can be directly applied to the surface of the movable block 500.

[0046] The mounting groove 211 is an inner cavity with two steps, consisting of a sealing section 211a and a connecting section 211b; the movable block 500 is movably disposed in the mounting groove 211, and the part of it is a columnar body with an outer diameter adapted to the sealing section 211a, and the columnar body is clearance-fitted with the sealing section 211a.

[0047] When the clamping block 300 switches to the released state, the moving block 500 moves to the first position along with the support shaft 100. At this time, the first seal 530 abuts against the inner wall of the sealing section 211a to form a seal, while the second seal 540 is located inside the connecting section 211b. Since the inner diameter of the connecting section 211b is larger than the outer diameter of the second seal 540, the second seal 540 is in an unloaded state, thereby forming an annular air passage gap between the outer peripheral surface of the moving block 500 and the inner wall of the connecting section 211b. At this time, the gas in the fourth airflow channel 520 flows into the second airflow channel 220 through this annular air passage gap, realizing the blowing and dust removal of the clamping block 300.

[0048] When the clamping block 300 switches to the clamping state, the support shaft 100 drives the moving block 500 to slide along the mounting groove 211. During this process, the second seal 540 is compressed into the sealing section 211a under the guidance of the guide cone surface or stepped surface, so that both the first seal 530 and the second seal 540 are tightly fitted with the inner wall of the sealing section 211a. At this time, the second seal 540 is in the second working position. At the same time, the opening of the fourth airflow channel 520 is completely confined in the sealed space of the sealing section 211a by the first seal 530 and the second seal 540 on both sides. Due to the obstruction of the inner wall of the sealing section 211a, the path between the fourth airflow channel 520 and the second airflow channel 220 is physically cut off.

[0049] By setting a sealing section 211a and a connecting section 211b with a diameter difference within the mounting groove 211, and combining the first seal 530 and the second seal 540 to block the opening of the fourth airflow channel 520, an instantaneous airflow bypass is established by utilizing the elastic recovery and radial clearance release of the second seal 540 when entering the large-diameter area. This achieves a mechanical self-drive connection for airflow switching, eliminates the time lag caused by solenoid valve switching, improves the airflow response speed during state switching, and ensures the synchronization of dust removal and clamping release actions. The increased diameter of the connecting section 211b can be achieved not only by circumferential enlargement but also by creating a local longitudinal drainage groove on the inner wall of the sealing section 211a to achieve airflow bypass.

[0050] In the clamped state, the first seal 530 and the second seal 540 together form a double axial limiting seal on the inner wall of the small-diameter sealing section 211a, which strictly restricts the high-pressure detection airflow inside the detection circuit, prevents the airflow from leaking into the self-cleaning circuit and causing back pressure interference, ensures the accuracy of pressure drop or flow data during air tightness testing, and effectively avoids detection misjudgment caused by internal air leakage.

[0051] Furthermore, a connecting block 600 is also movably disposed within the mounting cavity 210. One side of the connecting block 600 is fixedly connected to the moving block 500, and the other side is connected to each clamping block 300. The moving block 500 drives the clamping block 300 to switch between clamping and releasing states through the connecting block 600.

[0052] One side of the connecting block 600 can be fixedly connected to the moving block 500 by equal-height bolts. The other side of the connecting block 600 has a first annular groove 610 extending circumferentially. One end of each clamping block 300 together forms a second annular groove 310 that matches the first annular groove 610. The first annular groove 610 has a first flange 611 extending toward the axis, and the second annular groove 310 has a second flange 311 extending away from the axis. The first flange 611 is embedded in the second annular groove 310, and the second flange 311 is embedded in the first annular groove 610, thereby forming an interlocking limit in the axial direction.

[0053] When the support shaft 100 is driven by the machine tool drive shaft to move axially, the power is transmitted to each clamping block 300 through the moving block 500 and the connecting block 600, causing each clamping block 300 to move axially synchronously. During this process, since there are radial sliding gaps between the bottom of the first flange 611 and the second annular groove 310, and between the second flange 311 and the bottom of the first annular groove 610, when the clamping block 300 moves relative to the fixed seat 200, each clamping block 300 can radially contract or centrifugally expand relative to the connecting block 600, thereby achieving a smooth switch between the clamping state and the release state.

[0054] Furthermore, the opening end of the mounting cavity 210 is provided with a conical inner wall 212, and the outer sides of each clamping block 300 together form a conical surface 320 that is adapted to the conical inner wall 212, and the conical surface 320 slides against the conical inner wall 212.

[0055] When clamping is initiated, the machine tool drive shaft pushes the support shaft 100 to move axially toward the workpiece. This movement is transmitted to the multiple clamping block 300 assemblies through the moving block 500 and the connecting block 600. Since the outer conical surface 320 of each clamping block 300 always maintains sliding contact with the conical inner wall 212 of the fixed seat 200, under the action of axial thrust, the conical contact pair generates a radial component force perpendicular to the axis, forcing all clamping blocks 300 to contract towards the center simultaneously and uniformly. Finally, the contoured structure on its inner side tightly holds the workpiece, achieving stable and concentric clamping.

[0056] When switched to the release state, the machine tool drive shaft drives the support shaft 100 to move axially away from the workpiece. This movement is transmitted to the multiple clamping block 300 assemblies through the moving block 500 and the connecting block 600. Since the outer conical surface 320 of each clamping block 300 always maintains sliding contact with the conical inner wall 212 of the fixed seat 200, under the action of axial tension, the conical contact pair generates a radial component force perpendicular to the axis, forcing all clamping blocks 300 to expand outward simultaneously and uniformly, thereby releasing the clamping of the workpiece. At this time, the drive stroke of the external drive shaft driving the support shaft 100 to move along its own axis can be adjusted automatically according to the actual working conditions to ensure that the clamping blocks 300 will not be over-opened or even fall off due to centrifugal force or vibration during release.

[0057] By setting a conical inner wall 212 at the opening end of the mounting cavity 210, and having a conical surface 320 formed by multiple clamping blocks 300 slide against it; by utilizing the inclined wedge clamping principle, the axial linear driving force provided by the support shaft 100 is efficiently converted into the centripetal radial extrusion force of each clamping block 300 on the workpiece, and a normal positive pressure is generated at the contact interface, an extremely high force amplification ratio is achieved, ensuring that the clamping blocks 300 can firmly clamp the workpiece, effectively preventing axial movement of the workpiece or seal failure under the high pressure environment of airtightness testing.

[0058] Furthermore, the testing component 400 includes a coaxially arranged connecting portion 420, an inner portion 430, and an outer portion 440. A third airflow channel 410 is disposed inside the inner portion 430, and the outer portion 440 is sleeved on the outside of the inner portion 430. A second connecting through hole is provided in the connecting portion 420, one end of the inner portion 430 passes through the second connecting through hole, and one end of the outer portion 440 is inserted into the second connecting through hole.

[0059] Furthermore, the outer sleeve 440 has a longitudinally penetrating recessed hole 441 inside, and the end of the recessed part 430 away from the connecting part 420 extends into the recessed hole 441. The third airflow channel 410 communicates with the recessed hole 441, and the gas in the third airflow channel 410 is discharged into the recessed hole 441 and flows to the workpiece through the recessed hole 441.

[0060] A stable airflow transmission path is formed by the coaxially arranged connecting part 420, embedded part 430, and outer sleeve 440. The second connecting through hole in the connecting part 420 enables precise positioning of the embedded part 430 and the outer sleeve 440, ensuring the communication accuracy between the third airflow channel 410 and the embedded hole 441. The embedded hole 441 inside the outer sleeve 440 cooperates with the extension end of the embedded part 430, ensuring smooth airflow transmission and protecting the embedded part 430 from damage during clamping. The communication design between the third airflow channel 410 and the embedded hole 441 allows gas to flow precisely to the workpiece to be inspected. Combined with the clamping state of the clamping block 300, the airtightness of the workpiece can be detected, while preventing gas leakage and improving detection accuracy. In addition, this structure, through modular design, facilitates the processing and assembly of various components, reduces production costs, and improves the overall durability of the expansion sleeve.

[0061] Furthermore, the outer sleeve 440 is provided with a detection end 442 at the end away from the moving block 500, and the end face contour of the detection end 442 matches the bottom contour of the workpiece.

[0062] Furthermore, the sidewall of the detection end 442 is provided with at least one fifth airflow channel 443 serving as a feedback branch. The inlet end of the fifth airflow channel 443 is connected to the third airflow channel 410, and the exhaust end of the fifth airflow channel 443 extends to the end face of the detection end 442 and forms a detection opening 443a. Preferably, the sidewall of the detection end 442 is provided with three fifth airflow channels 443, and three detection openings 443a are formed on the corresponding surface of the detection end 442.

[0063] During operation, the workpiece is placed on the detection piece 400. At this time, the bottom of the workpiece abuts against the end face of the detection end 442 of the outer sleeve 440. Then, the support shaft 100 drives each clamping block 300 to slide along the inner wall 212 of the cone through the conical surface 320 until it switches to the clamping state. At this time, the clamping block 300 has a downward clamping force on the workpiece, forcing the bottom surface of the workpiece to press tightly against the end face of the detection end 442. At this time, the detection opening 443a is physically blocked by the bottom surface of the workpiece and forms a seal. When the workpiece is tested for air tightness, part of the gas in the third airflow channel 410 flows to the detection opening 443a along the air inlet of the fifth airflow channel 443. The external flow monitoring device or pressure sensor determines whether the workpiece is installed in place by detecting the air pressure change in the third airflow channel 410. If the workpiece is tilted or not tightly fitted, or if at least one of the three detection points leaks, the external flow monitoring device or pressure sensor will detect that the pressure in the third airflow channel 410 is less than the preset range, and then determine that the clamping state is abnormal and trigger an alarm. The inner diameter of the fifth airflow channel 443 is carefully designed so that it will not be too large and affect the flow of gas in the third airflow channel 410 to the workpiece to be tested through the embedded hole 441.

[0064] A contoured detection end 442 surface that precisely matches the bottom contour of the workpiece is provided at the end of the outer sleeve 440. The axial clamping force provided by the clamping block 300 forms a physical contact interface between the workpiece reference surface and the detection end 442 surface. This not only provides stable axial support for the workpiece, but also ensures the sealing reliability between the internal test chamber of the workpiece and the detection air path, eliminating the interference of mechanical vibration caused by workpiece skewing on the detection accuracy.

[0065] By setting up three fifth airflow channels 443 and corresponding three detection openings 443a, a multi-point detection feedback mechanism is formed. The bottom surface of the workpiece is used as a "valve core" to block the detection openings 443a, transforming the mechanical state of "workpiece in physical position" into a physical signal of "pressure jump" in the air path. This achieves automatic monitoring and error prevention of the clamping state, ensuring that the airtightness test is triggered only when the workpiece is completely sealed and in contact with the surface, and completely eliminating the phenomenon of "false missed detection" or false alarm caused by improper clamping.

[0066] It should be noted that in this invention, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. The terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or integration; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly specified. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0067] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0068] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A self-cleaning expansion sleeve for testing the airtightness of workpieces, characterized in that, include: A support shaft having a first airflow channel inside, the support shaft having an interface for connecting an external air source; A fixed base has a mounting cavity and a second airflow channel inside, and one end of the support shaft is movably inserted into the mounting cavity; Multiple clamping blocks are movably disposed within the mounting cavity and are drively connected to the support shaft; each clamping block has a clamping state that is close to each other and a released state that is far from each other, and when in the released state, there is a gap between two adjacent clamping blocks; A detection element is movably disposed within the mounting cavity, with one end of the detection element being drively connected to the support shaft and the other end extending between each of the clamping blocks. The detection element is provided with a third airflow channel, which communicates with the first airflow channel. When in the released state, the first airflow channel is connected to the second airflow channel, and the gas in the first airflow channel flows through the second airflow channel to the gap between each clamping block to purge the gap between the clamping blocks. When in the clamping state, the first airflow channel is disconnected from the second airflow channel, and the gas in the first airflow channel flows to the workpiece through the third airflow channel for airtightness testing of the workpiece.

2. The expansion sleeve with self-cleaning function as described in claim 1, characterized in that, A movable block is also provided in the mounting cavity, and a first connecting through hole is provided in the movable block; one end of the support shaft is inserted into one end of the first connecting through hole, and the end of the detection element away from the clamping block is inserted into the other end of the first connecting through hole, and the first airflow channel and the third airflow channel are connected through the first connecting through hole.

3. The expansion sleeve with self-cleaning function as described in claim 2, characterized in that, The inner wall of the mounting cavity is provided with a mounting groove that communicates with the second airflow channel. The movable block is at least partially movable within the mounting groove, and the movable block is provided with a fourth airflow channel that communicates with the first connecting through hole. When the clamping block is in the released state, the fourth airflow channel is connected to the mounting slot; When the clamping block is in the clamping state, the fourth airflow channel is disconnected from the mounting groove.

4. The expansion sleeve with self-cleaning function as described in claim 3, characterized in that, The mounting groove includes a sealing section and a connecting section arranged sequentially along its axial direction, the inner diameter of the connecting section being larger than the inner diameter of the sealing section; a first sealing element and a second sealing element are embedded at intervals along the axial direction on the outer side wall of the movable block, the opening of the fourth airflow channel is located on the side wall of the movable block between the first sealing element and the second sealing element, the first sealing element slides against the inner wall of the sealing section, and the second sealing element has a first working position located within the connecting section and a second working position abutting against the inner wall of the sealing section.

5. The expansion sleeve with self-cleaning function as described in claim 2, characterized in that, A connecting block is also movably disposed within the mounting cavity. One side of the connecting block is fixedly connected to the moving block, and the other side is connected to each of the clamping blocks. The moving block drives the clamping blocks to switch between the clamping state and the releasing state through the connecting block.

6. The expansion sleeve with self-cleaning function as described in claim 1, characterized in that, The opening end of the mounting cavity has a conical inner wall, and the outer walls of each clamping block together form a conical surface that is adapted to the conical inner wall, and the conical surface slides against the conical inner wall.

7. The expansion sleeve with self-cleaning function as described in claim 2, characterized in that, The detection component includes a coaxially arranged connecting part, an inner part, and an outer part. The third airflow channel is disposed inside the inner part, and the outer part is sleeved on the outside of the inner part. One end of the connecting part is inserted into the first connecting through hole of the moving block, and the connecting part is provided with a through second connecting through hole. One end of the inner part passes through the second connecting through hole, and one end of the outer part is inserted into the second connecting through hole.

8. The expansion sleeve with self-cleaning function as described in claim 7, characterized in that, The outer sleeve has a through-hole, and one end of the inner sleeve away from the connecting part extends into the inner hole, and the inner hole communicates with the third airflow channel.

9. The expansion sleeve with self-cleaning function as described in claim 7, characterized in that, The outer sleeve is provided with a detection end at the end away from the moving block. The end face contour of the detection end is adapted to the bottom contour of the workpiece. When in the clamping state, the end face of the detection end abuts against the bottom of the workpiece to seal the position to be detected on the workpiece.

10. The expansion sleeve with self-cleaning function as described in claim 9, characterized in that, At least one fifth airflow channel is also provided inside the side wall of the detection end. The air inlet of the fifth airflow channel is connected to the third airflow channel, and the exhaust end of the fifth airflow channel extends to the end face of the detection end to form a detection opening.

Images