SMA straight head integrated automatic assembly process

Abstract

The invention belongs to the technical field of communication, and particularly relates to an SMA straight head integrated automatic assembly process which is executed based on an integrated system, and the system comprises a wire feeding unit, a step-by-step peeling unit, a shielding layer composite processing unit and a closed-loop process control system. The wire rod is a coaxial radio frequency cable of which the outer diameter is matched with that of the SMA straight head connector; the wire releasing and conveying unit is used for releasing and conveying wires; the step-by-step peeling unit is used for sequentially peeling an outer layer insulating skin and a shielding layer outer sheath at two ends of the wire rod, and exposing a conductor and a shielding layer; according to the utility model, the shielding layer is in a tensioning state through controllable counter-pulling, and finally, the crimping pipe is axially sleeved and riveted, so that not only is the broken wire damage caused by scraping avoided, but also the low-impedance and large-area reliable electric contact between the shielding layer and the shell is ensured, and the shielding effectiveness and the anti-interference capability of the connector in high-frequency signal transmission are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, specifically a fully automated assembly process for SMA straight connectors. Background Technology

[0002] SMA straight connectors are coaxial connectors widely used in fields such as radio frequency communication, test and measurement, radar, and 5G base stations. Their typical structure includes a center conductor pin, a dielectric insulator, a metal shell, and crimp / weld ends. The so-called SMA straight connector integrated automated assembly process refers to integrating multiple processes such as end processing of coaxial radio frequency cables, center conductor pin welding, shielding layer processing, shell mounting, riveting and fixing, heat shrink protection, and electrical performance testing into a continuous and intelligent automated system, realizing unmanned manufacturing from wire input to finished product output.

[0003] Currently, the assembly of SMA straight connectors in the industry generally adopts semi-automatic or substation-based automation methods. This type of process usually consists of multiple independent workstations, such as manual loading followed by mechanical peeling, manual soldering, pneumatic shell insertion, and offline testing. Although some advanced production lines have introduced single-point automation technologies such as vibratory feeder feeding, servo wire feeding, and CCD vision positioning, which can improve production efficiency and consistency to a certain extent, the overall process still relies on manual handling and visual judgment. It can only achieve the mechanization of some processes and has not yet formed a truly integrated closed-loop production system.

[0004] However, the aforementioned existing technologies reveal the following insurmountable technical defects when facing the manufacturing demands of modern RF connectors requiring high reliability, high volume, and quick replacement: First, the processes are fragmented and lack coordinated control. Key steps such as wire laying, stripping, pin soldering, and shielding are performed in isolation, requiring multiple clamping and transfer of the wires, which easily introduces positional offset and cumulative errors, resulting in poor soldering coaxiality and poor shielding contact. Second, the shielding layer processing is crude, often using scrapers or simple folding, which cannot guarantee uniform outward folding of the shielding wires and reliable electrical contact, making it difficult to meet the requirements of high-frequency applications in terms of signal integrity and anti-interference capabilities. Third, detection and control are disconnected. Quality inspection is mostly done offline sampling or post-production full inspection, and defective products cannot be intercepted in real time during the process, resulting in ineffective processing, material waste, and the risk of good products being mixed in, which restricts further improvement in yield and production capacity. Therefore, a SMA straight-head integrated automated assembly process is proposed to address the above problems. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art and solve at least one of the technical problems mentioned in the background art, the present invention proposes an SMA straight head integrated automated assembly process.

[0006] The technical solution adopted by the present invention to solve its technical problem is: an SMA straight connector integrated automated assembly process described in the present invention, the process is based on an integrated system, the system includes a wire feeding unit, a step-by-step stripping unit, a shielding layer composite processing unit and a closed-loop process control system; the wire is a coaxial RF cable with an outer diameter adapted to the SMA straight connector. The wire delivery unit is used to release and transport the wire; the step-by-step stripping unit sequentially strips the outer insulation layer and the outer sheath of the shielding layer from both ends of the wire, exposing the conductor and the shielding layer. The shielding layer composite processing unit executes the following sequentially: S1. A pair of high-speed rotating flexible brushes act synchronously from both radial sides, causing the shielding layer to fold outwards evenly and adhere to the outer sheath to form an annular conductive flange. S2. The outward-folding part is clamped by the axial anti-pull mechanism and stretched backward to a preset length, so that the shielding layer is in a tensioned state. S3. Under tension, pull the crimped tube axially back from the end of the wire to cover the shielding layer, and rivet it to form an integrated mechanical-electrical connection structure; The closed-loop process control system establishes process logic dependencies based on the status of each unit and detection signals. Subsequent processes are only allowed to start if the preceding process is qualified. If there is an abnormality or failure, the process is immediately interrupted and an alarm is triggered, thus achieving fully closed-loop unmanned assembly.

[0007] Preferably, the integrated system further includes a welding needle and heat shrink tubing assembly unit for simultaneously completing the welding of the SMA needle body and the fixed-length fitting of the heat shrink tubing at the exposed end of the conductor, wherein the heat shrink tubing fitting is located adjacent to the welding point.

[0008] Preferably, the integrated system further includes a connector insertion unit for inserting the SMA straight-head shell connector axially onto the welded needle body and achieving mechanical positioning and electrical connection; during the insertion process, visual alignment is used to ensure that the coaxiality of the connector and the needle body meets the assembly requirements.

[0009] Preferably, the integrated system further includes a multi-dimensional online detection unit, configured after the connector insertion unit, for synchronously performing the following on the semi-finished product that has been inserted: A. Visual inspection to determine the integrity of the needle and whether its position has shifted; B. PIN height detection to confirm that its extension length is within the preset acceptable range; C. Electrical performance testing to detect short circuits or insulation failures; The multidimensional online detection unit outputs a comprehensive qualified signal to the closed-loop process control system.

[0010] Preferably, the integrated system further includes a segmented heat shrink unit, the start-up of which is controlled by the closed-loop process control system according to the comprehensive pass signal; the segmented heat shrink unit only performs heat shrink operation when the comprehensive judgment is qualified.

[0011] Preferably, the segmented heat shrink unit includes a hot air heating device and an axial positioning clamping mechanism. The heat shrinking process is divided into a low-temperature preheating stage and a high-temperature shaping stage. The heat shrink tube is uniformly wrapped around the transition area of ​​the compression tube and the joint through two axial positioning operations.

[0012] Preferably, the wire feeding unit includes a servo-driven wire feeding mechanism and a tension buffer device. The wire feeding speed is linked to the cycle time of subsequent processes, and a constant tension is maintained during wire feeding to avoid conductor damage or shielding layer deformation.

[0013] Preferably, the step-by-step stripping unit includes a first stripping station and a second stripping station; the first stripping station removes the outer sheath of the wire to expose the shielding layer, and the second stripping station further peels off the dielectric layer inside the shielding layer to expose the center conductor; the stripping depth of the two stations is independently adjustable.

[0014] Preferably, in the shielding layer composite processing unit, the high-speed rotating flexible brush is made of an antistatic flexible material; the axial anti-pull mechanism applies a controllable tension to the outward-facing portion of the shielding layer, keeping it in a taut state without breaking.

[0015] Preferably, the closed-loop process control system is built on a programmable logic controller or an industrial computer, which collects the status signals and detection results of each unit in real time and establishes interlocking logic between processes. When the detection fails or the equipment malfunctions, the system immediately terminates the current product process, triggers an alarm, and automatically diverts defective products to an isolation station, while recording fault information for traceability.

[0016] The beneficial effects of this invention are: This invention provides an automated assembly process for SMA straight connectors. By integrating core processes such as wire feeding, step-by-step stripping, and shielding layer composite processing into the same system and uniformly scheduling them by a closed-loop process control system, it achieves temporal coordination and spatial continuity between units. The wires do not require manual intervention or multiple re-clamping throughout the process, effectively avoiding positional offsets and cumulative errors caused by transfer in traditional station-based processes. This significantly improves welding coaxiality and overall assembly accuracy, laying the foundation for high-consistency mass production.

[0017] This invention provides an automated assembly process for SMA straight connectors. It employs a three-step composite shielding process: flexible brush outward turning, axial reverse tensioning, and crimping and riveting. A high-speed rotating flexible brush causes the shielding wires to evenly turn outward and adhere to the outer sheath, forming an annular conductive flange. Controllable reverse tensioning keeps it in a tensioned state. Finally, the crimping tube axially retracts and rivets the connector. This process not only avoids wire breakage damage caused by scraping but also ensures low impedance and large-area reliable electrical contact between the shielding layer and the outer shell, significantly improving the connector's shielding effectiveness and anti-interference capability in high-frequency signal transmission.

[0018] This invention provides an automated assembly process for SMA straight-head integrated assembly. By introducing a closed-loop process control mechanism based on real-time detection signals, a strict process logic dependency relationship is established: subsequent processes are only allowed to start when the preceding unit is completed and in a qualified state; once an abnormality or non-conformity is detected, the system immediately interrupts the process, triggers an audible and visual alarm, and isolates defective products. This mechanism realizes a fully closed-loop unmanned control of "detection is interception, and only qualified products are allowed to flow", completely eliminating invalid processing and the mixing of defective products, and significantly improving the yield, material utilization rate, and production line automation level. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention.

[0020] In the attached diagram: Figure 1 This is a schematic diagram of the process flow of the present invention; Figure 2 This is a flowchart illustrating the assembly unit of the welding pin and heat shrink tubing in this invention. Figure 3 This is a flowchart illustrating the connector insertion unit in this invention; Figure 4 This is a flowchart illustrating the multidimensional online detection unit in this invention; Figure 5 This is a schematic diagram of the segmented heat shrink unit in this invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Specific implementation examples are given below.

[0023] Please see Figures 1-5 This invention provides an automated assembly process for SMA straight connectors. The overall system consists of eight functional modules: a wire feeding unit, a step-by-step stripping unit, a shielding layer composite processing unit, a welding pin and heat shrink tubing assembly unit, a connector insertion unit, a multi-dimensional online detection unit, a segmented heat shrink unit, and a closed-loop process control system. Each module is interconnected with an industrial real-time bus via mechanical transmission, pneumatic actuators, and shares a unified event triggering mechanism. All critical actions are executed based on synchronous pulse sequences generated by the PLC's built-in hardware timer, with time jitter controlled within milliseconds. This ensures seamless and uninterrupted connection between processes under typical production cycles (cycle ≤ 6.5 seconds / piece).

[0024] In this embodiment, such as Figures 1-3 As shown, the wire feeding unit, serving as the starting point of the entire feed path, is equipped with a servo motor-driven wire feeding reel and a floating tension lever mechanism. The wire feeding reel can carry coaxial RF cables with outer diameters compatible with SMA straight connectors (typical specifications such as RG178 and RG316, outer diameter range 1.13–5.0 mm, wire reel weight ≤ 50 kg). The servo motor uses a 400W rated power AC servo system, combined with the motion controller's built-in S-shaped acceleration and deceleration algorithm, to achieve a smooth, shock-free transition during start-up, constant speed, and stopping, suppressing wire jitter caused by inertial disturbances. The floating lever mechanism consists of a lightweight aluminum alloy arm, an inertial guide roller, and a high-resolution angular displacement sensor. Its swing angle reflects the wire tension status in real time and serves as an auxiliary feedback signal input to the PLC to compensate for low-frequency tension fluctuations caused by servo response lag. This dual-stage tension control structure can maintain tension fluctuations within ±5% of the set value during wire feeding, effectively preventing shielding collapse or center conductor stretching; subsequently, the wire enters the straightening station. The straightening mechanism includes a pair of arc-shaped anti-slip grippers made of quenched Cr12MoV steel. After clamping the wire end, it rotates at a high speed of ≥300r / min and simultaneously applies an axial tensile force of 0.3–0.8MPa, so that the wire eliminates bending under the combined stress of rotation and tension, ensuring that the coaxiality error of subsequent stripping and welding is ≤0.01mm. After straightening, the servo wire feeding mechanism cuts the wire to a preset length (e.g., 2m) with an accuracy of ±0.15%. The cut wire is then automatically wound into a figure-eight or circle shape by the winding machine and temporarily stored on the transfer platform to complete the initial material preparation, making it easier to transfer the wire to the next workstation in batches.

[0025] In this embodiment, such as Figures 1-3As shown, the step-by-step stripping unit comprises two independently controlled coaxial stripping machines, arranged sequentially along the wire conveying path. The first stripping station uses a rotating tungsten steel cutter to peel off the outer PVC or PE insulation sheath, exposing the inner braided shielding layer. The second stripping station precisely removes the thin layer of dielectric material (such as FEP Teflon) inside the shielding layer, exposing the central conductor. The stripping depth of the two stations is independently fine-tuned via a precision ball screw mechanism, with an adjustment resolution of 0.01mm, ensuring no damage to the shielding wire and conductor. After stripping, the wire ends form a clear three-layer structure: outer sheath, shielding layer, and central conductor, providing a reliable foundation for subsequent welding and shielding treatment. After stripping and before welding, the system simultaneously performs heat shrink tubing installation and laser marking: a stepper motor drives a tubing feeding mechanism to cut the heat shrink tubing to a fixed length (length error ±0.2mm), and precisely installs it onto the wire at a preset position via a guide sleeve; simultaneously, a fiber laser marking machine prints product identification in a designated area, including specifications, production batch, and a QR code, achieving full traceability.

[0026] In this embodiment, such as Figures 1-4 As shown, the shielding layer composite processing unit performs three steps in sequence: First, a pair of high-speed rotating flexible brushes (500–1200 r / min) act synchronously on the end of the shielding layer from both radial sides. The brush material is antistatic carbon fiber composite nylon (Shore hardness A70–80), which makes the shielding wires evenly turn outward and attach to the surface of the outer sheath, forming an annular conductive flange. Second, the miniature pneumatic gripper of the axial pull mechanism clamps the outward-turned part and pulls it backward to the preset position (typical stroke 2.0–4.0 mm, tension 0.5–1.5 N), so that the shielding layer is in a moderately tensioned state without breaking. Finally, the crimping tube (copper alloy material, inner diameter slightly larger than the outer diameter of the shielding layer) is fed by the vibratory plate and pushed to the end of the wire. Then, the pull-back cylinder axially re-fits it to the outside of the tensioned shielding layer. Subsequently, the 2T-class pressure terminal machine drives the hexagonal crimping head to complete the crimping, forming a strong integrated mechanical-electrical connection structure.

[0027] In this embodiment, such as Figures 1-4As shown, the soldering pin and heat shrink tubing assembly unit achieves sequential coordination between soldering and heat shrink tubing positioning. SMA male or female pins are fed by a vibratory feeder with a switchable tray, and transferred to the soldering station via a sorting turntable. A solder wire cutter cuts 0.8mm diameter solder wire and delivers it to the soldering point. A high-frequency soldering iron heats the wire to 300℃ to complete the soldering. Simultaneously, a stepper motor drives a tubing feeding mechanism to cut the heat shrink tubing to a preset length (typically 5–10mm). The pin feeding mechanism first positions the pin body on the soldering pin platform. The wire feeding module pushes the wire tip to the pin guide sleeve. After the guide sleeve is pneumatically opened, wire feeding continues, ensuring the center conductor is precisely inserted into the pin body hole to complete the connection. The wire feeding mechanism then retracts, ensuring precise and unbiased soldering position. The guide sleeve is then precisely fitted onto the wire approximately 5mm from the solder point. The entire process is coordinated by a PLC to ensure strict synchronization of the four actions: wire feeding, pin feeding, solder feeding, and tubing feeding, avoiding interference.

[0028] In this embodiment, such as Figures 2-4 As shown, the connector insertion unit includes an SMA straight-head shell vibration sorting device, a linear vibration feeding track, and secondary precision positioning grippers. The grippers are driven by a closed-loop stepper motor and a ball screw, achieving a positioning repeatability of ±0.02mm. Before insertion, a CCD vision system identifies the needle position, and the grippers dynamically compensate accordingly to ensure that the coaxiality error between the shell axis and the needle does not exceed 0.015mm, achieving reliable mechanical stopping and electrical connection.

[0029] In this embodiment, such as Figures 2-5 As shown, the multi-dimensional online detection unit is configured after the connector is installed, integrating three detection functions: (a) a 5-megapixel CCD camera captures images of the pin area, and the image processing algorithm determines the integrity of the pin and whether there is any offset; (b) a Keyence GT2 series high-precision displacement sensor detects whether the PIN pin extension height is within the acceptable range of 0–5mm, with a detection accuracy of ±0.005mm; (c) a high-voltage tester applies a 2kV DC voltage for 3 seconds, and a gold-plated beryllium copper probe contacts the core wire and the outer shell to detect whether there is a short circuit or insulation breakdown. The three results are fused and judged by the PLC, and a comprehensive qualified signal is output.

[0030] In this embodiment, such as Figures 1-5 As shown, the closed-loop process control system is built based on the Xinje XC3-48T-E PLC, with an operating cycle of 10ms, and integrates a process interlock logic algorithm. The logical expression of this algorithm is as follows: The system will only activate the segmented heat shrink unit when all four signals—wire arrival, stripping completion, shielding completion, welding temperature compliance, and multi-dimensional inspection pass—are true. If any signal is abnormal or the inspection fails, the PLC will immediately output a stop command, cut off the enable of the relevant actuators, and trigger an alarm. Simultaneously, defective product information (including fault type, timestamp, and batch number) will be recorded in local memory, supporting quality traceability.

[0031] In this embodiment, such as Figures 2-3 As shown, the segmented heat shrink unit includes a dual-stroke heat shrink tubing retraction mechanism and an intelligent temperature-controlled hot air gun. The retraction mechanism first performs a coarse positioning to ensure the heat shrink tubing covers the transition area between the crimped tube and the joint, and then performs a second fine positioning to align both ends with the preset boundaries. The hot air gun heats in two stages: the first stage is preheating at 120–150℃ for 3–5 seconds to eliminate internal stress; the second stage is setting at 180–220℃ for 2–4 seconds to ensure the heat shrink tubing shrinks evenly. The temperature is regulated by a PID controller with an accuracy of ±5℃. The unit is only authorized to start when the PLC receives a comprehensive pass signal to avoid ineffective processing of defective products. After heat shrinking, the products enter the unloading and sorting station. A servo motor drives a belt module to run the unloading mechanism. Based on the good / defective judgment signal output by the PLC, the reversing valve drives the guide plate to switch channels: good products flow into the finished product box, and defective products are guided into the isolation waste box, realizing automatic sorting and physical isolation.

[0032] Understandably, to verify the technical effect of the present invention, the following embodiments and comparative examples were designed for comparative testing. All experiments used RG178 coaxial cables with an outer diameter of 1.8mm and a length of 2m, SMA male connectors, and the production cycle was uniformly set to 560pcs / H (i.e., single-piece cycle ≈ 6.43 seconds).

[0033] Example 1: The complete process system of the present invention is adopted, including three-step shielding layer processing, closed-loop control, multi-dimensional online detection and condition-triggered heat shrinking.

[0034] Example 2: Based on Example 1, the multidimensional detection unit is turned off, and the heat shrink unit is always on (i.e., unconditional heat shrink).

[0035] Comparative Example 1: Using traditional semi-automatic process, manual peeling, manual welding, offline sampling inspection (sampling rate 10%), without shielding layer tensioning treatment.

[0036] Comparative Example 2: Automated equipment was used, but the shielding layer was only turned outward by scraping, without reverse tensioning or re-riveting.

[0037] Each group ran continuously for 4 hours, recording the following indicators: yield (full functional and appearance inspection), standard deviation of shielding layer contact resistance, UPH (actual output), and defective product mix-in rate. The test results are summarized in the table below: Data analysis shows that Example 1 significantly outperforms the comparative example in all indicators, especially in shielding reliability and zero-defect flow. While Example 2 maintains high efficiency, the lack of a detection and blocking mechanism leads to some defective products flowing into the finished product, increasing rework costs. Comparative Example 1 suffers from poor consistency due to excessive human intervention; Comparative Example 2, with its rough shielding treatment, exhibits large fluctuations in contact resistance, affecting high-frequency signal transmission performance.

[0038] Furthermore, in Example 1, the flexible brush underwent 100,000 cycles of wear testing. SEM observation showed that the bristles were only slightly worn down, with no breakage or detachment. The crimping head had a lifespan exceeding 500,000 cycles without significant deformation. This demonstrates that the key consumables possess long-term service reliability.

[0039] Furthermore, the system also offers advantages in changeover and commissioning. When changing to different specifications of SMA male / female connectors or wire lengths (0.5–5m), only the tray model needs to be switched and PLC parameters (such as step distance, heat shrink position, and detection threshold) adjusted via the human-machine interface, without requiring any replacement of the mechanical structure. Typical changeover time is reduced from 40 minutes in traditional processes to 25 minutes, and the overall equipment efficiency (OEE) is improved by 18%.

[0040] In summary, this invention achieves high yield, high consistency, and unmanned assembly of SMA straight connectors under high-cycle conditions through a three-step method of shielding layer outward flipping-tensioning-returning riveting, multi-dimensional online detection and conditional execution mechanism, and closed-loop interlocking control throughout the entire process. Its technical features work synergistically to solve core challenges in the automated production of RF connectors, such as unreliable shielding, process disconnect, and delayed detection, providing a reliable process foundation for high-end manufacturing fields such as 5G communication, radar, and testing instruments.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. An automated assembly process for SMA straight head integrated assembly, characterized in that: The process is performed based on an integrated system, which includes a wire delivery unit, a step-by-step stripping unit, a shielding layer composite processing unit, and a closed-loop process control system; the wire is a coaxial RF cable with an outer diameter adapted to an SMA straight connector. The wire delivery unit is used to release and transport the wire; the step-by-step stripping unit sequentially strips the outer insulation layer and the outer sheath of the shielding layer from both ends of the wire, exposing the conductor and the shielding layer. The shielding layer composite processing unit executes the following sequentially: S1. A pair of high-speed rotating flexible brushes act synchronously from both radial sides, causing the shielding layer to fold outwards evenly and adhere to the outer sheath to form an annular conductive flange. S2. The outward-folding part is clamped by the axial anti-pull mechanism and stretched backward to a preset length, so that the shielding layer is in a tensioned state. S3. Under tension, pull the crimped tube axially back from the end of the wire to cover the shielding layer, and rivet it to form an integrated mechanical-electrical connection structure; The closed-loop process control system establishes process logic dependencies based on the status of each unit and detection signals. Subsequent processes are only allowed to start if the preceding process is qualified. If there is an abnormality or failure, the process is immediately interrupted and an alarm is triggered, thus achieving fully closed-loop unmanned assembly.

2. The SMA straight-head integrated automated assembly process as described in claim 1, characterized in that: The integrated system further includes a welding needle and heat shrink tubing assembly unit, used to simultaneously complete the welding of the SMA needle body and the fixed-length fitting of the heat shrink tubing at the exposed end of the conductor, wherein the heat shrink tubing fitting is located adjacent to the welding point.

3. The SMA straight-head integrated automated assembly process as described in claim 1, characterized in that: The integrated system further includes a connector insertion unit for axially inserting the SMA straight-head housing connector onto the welded needle body and achieving mechanical stop and electrical connection; during the insertion process, visual alignment is used to ensure that the coaxiality of the connector and the needle body meets the assembly requirements.

4. The SMA straight-head integrated automated assembly process as described in claim 1, characterized in that: The integrated system further includes a multi-dimensional online detection unit, configured after the connector insertion unit, for synchronously performing the following on the semi-finished product that has been inserted: A. Visual inspection to determine the integrity of the needle and whether its position has shifted; B. PIN height detection to confirm that its extension length is within the preset acceptable range; C. Electrical performance testing to detect short circuits or insulation failures; The multidimensional online detection unit outputs a comprehensive qualified signal to the closed-loop process control system.

5. The SMA straight-head integrated automated assembly process as described in claim 1, characterized in that: The integrated system further includes a segmented heat shrink unit, whose activation is controlled by the closed-loop process control system based on the comprehensive pass signal; the segmented heat shrink unit only performs heat shrinking operation when the comprehensive judgment is qualified.

6. The SMA straight-head integrated automated assembly process as described in claim 5, characterized in that: The segmented heat shrink unit includes a hot air heating device and an axial positioning clamping mechanism. The heat shrinking process is divided into a low-temperature preheating stage and a high-temperature shaping stage. The heat shrink tube is uniformly wrapped around the transition area of ​​the compression tube and the joint through two axial positioning operations.

7. The SMA straight-head integrated automated assembly process as described in claim 1, characterized in that: The wire feeding unit includes a servo-driven wire feeding mechanism and a tension buffer device. The wire feeding speed is linked to the cycle time of subsequent processes, and a constant tension is maintained during the wire feeding process to avoid deformation of the shielding layer or damage to the conductor.

8. The SMA straight-head integrated automated assembly process as described in claim 1, characterized in that: The step-by-step stripping unit includes a first stripping station and a second stripping station; the first stripping station removes the outer sheath of the wire to expose the shielding layer, and the second stripping station further peels off the dielectric layer inside the shielding layer to expose the center conductor; the stripping depth of the two stations is independently adjustable.

9. The SMA straight-head integrated automated assembly process as described in claim 1, characterized in that: In the shielding layer composite processing unit, the high-speed rotating flexible brush is made of antistatic flexible material; the axial anti-pull mechanism applies a controllable tension to the outward-facing part of the shielding layer, keeping it in a taut state without breaking.

10. The SMA straight-head integrated automated assembly process as described in claim 1, characterized in that: The closed-loop process control system is built on a programmable logic controller or an industrial computer. It collects the status signals and detection results of each unit in real time and establishes interlocking logic between processes. When the detection fails or the equipment malfunctions, the system immediately terminates the current product process, triggers an alarm, and automatically diverts defective products to an isolation station. At the same time, it records the fault information for traceability.

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