Automatic testing and grading system for PTC (Positive Temperature Coefficient) thermosensitive element

Abstract

The invention belongs to the technical field of material detection, and particularly discloses an automatic testing and grading system for PTC thermosensitive elements. The system comprises a conveying device, an R25 detection device, a rejecting and material supplementing device, a multi-stage detection device, an appearance detection device, a graded discharging device and a control module, the system is provided with a feeding station, a first conveying path and a second conveying path, the R25 detection device comprises an R25 initial detection unit and an R25 redetection unit, and the R25 initial detection unit comprises an R25 initial detection unit and an R25 redetection unit. The multi-stage detection device comprises a plurality of first-stage units and a plurality of second-stage units; the control module is electrically connected with all the devices and used for controlling conveying path switching and testing grading of the system. The automatic testing and grading system has the characteristics of high automation degree and high efficiency.

Description

Technical Field

[0001] This application belongs to the field of materials testing technology, and more specifically, relates to an automatic testing and grading system for PTC thermistors. Background Technology

[0002] PTC thermistors are semiconductor ceramic elements whose resistance increases significantly with increasing temperature. In the electronics manufacturing industry, PTC thermistors are widely used due to their excellent temperature control performance.

[0003] However, current PTC thermistor testing systems generally suffer from prominent problems such as low testing efficiency and poor grading. Especially in multi-station assembly line testing operations, the different items tested at each station often have varying time requirements, leading to lengthy production paths and waiting times. Furthermore, during the testing process, defective PTC thermistors detected at one station often flow to the next station along with the tray, consuming the limited performance resources of the testing system and significantly reducing overall testing efficiency, thus hindering the smooth operation of the production process. Therefore, improvements are urgently needed. Summary of the Invention

[0004] In response to the deficiencies or improvement needs of existing technologies, this application provides an automatic testing and grading system for PTC thermistors, aiming to improve the low production efficiency of PTC thermistor detection and grading.

[0005] This application provides an automatic testing and grading system for PTC thermistors, specifically including a conveying device, an R25 detection device, a rejection and replenishment device, a multi-stage detection device, a visual inspection device, a grading and unloading device, and a control module. The system is equipped with a loading station and a first conveying path and a second conveying path, wherein: The R25 testing device includes an R25 initial testing unit and an R25 retesting unit. The multi-level testing device includes multiple primary units and multiple secondary units. The control module is electrically connected to each device to control the switching of the system's transport path and the classification of tests. In the first conveying path, the conveying device first conveys the tray containing PTC thermistors from the loading station to the R25 initial inspection unit for R25 initial inspection; then the rejection and replenishment device removes the PTC thermistors in the tray that exceed the R25 initial inspection standard, and temporarily stores the PTC thermistors that pass the initial inspection; the empty tray is returned to the loading station. In the second conveying path, the conveying device sequentially sends multiple trays containing PTC thermistors from the loading station to the R25 initial inspection unit for testing. Then, a rejection and replenishment device removes substandard PTC thermistors and replenishes the trays with temporarily stored PTC thermistors. Next, the trays are transferred to the R25 re-inspection unit for R25 re-testing, then diverted to multiple primary units for withstand voltage and Rmin testing of the PTC thermistors. They are then transferred to multiple secondary units for temperature and capacitance testing, and finally converged to the appearance inspection device for appearance inspection. Finally, they are transferred to the sorting and unloading device. The control module controls the sorting and unloading device to sort the PTC thermistors according to the test results of each testing device. Empty trays after sorting are returned to the loading station.

[0006] As a further preferred embodiment, the conveying device includes a main conveyor, branch conveyors, auxiliary conveyors, a lifting and translating machine, and a lifting and rotating machine, wherein: The main conveyor is arranged in multiple ways along the same direction, including an upper conveying section and a lower return section; Multiple lifting and translating machines are provided for transferring material trays between two adjacent main conveyors and between the upper conveying section and the lower return section. Multiple branch conveyors are arranged side by side, and the two ends of each branch conveyor are connected to the upper conveyor section and the auxiliary conveyor respectively through a lifting and indexing machine.

[0007] As a further preferred embodiment, the rejection and replenishment device includes: A gripping mechanism is used to pick up, place, and transfer PTC thermistors on a tray. The substandard product storage facility is used to store PTC thermistors that exceed the R25 test standard and are removed by the gripping mechanism. The qualified product temporary storage mechanism is used to temporarily store PTC thermistors that have passed the R25 test and have been removed by the gripping mechanism.

[0008] As a further preferred embodiment, the primary unit includes a pressure resistance mechanism, a temperature regulation mechanism, and an Rmin testing mechanism, wherein: The withstand voltage mechanism is used to apply a test voltage to the PTC thermistor in the tray to detect the insulation performance of the PTC thermistor. The temperature regulation mechanism is used to regulate the temperature of the PTC thermistor in the tray, so that the temperature of the PTC thermistor in the tray reaches the preset room temperature range. The Rmin test mechanism is used to test the minimum resistance value of a PTC thermistor under normal temperature conditions.

[0009] As a further preferred embodiment, the secondary unit includes an infrared imaging mechanism and a capacitance testing mechanism, wherein: The infrared imaging mechanism is used to acquire real-time thermal distribution images of the PTC thermistor in the material tray and generate temperature information. The control module determines whether the temperature of the PTC thermistor meets the standard based on the temperature information and the preset temperature acceptable range. The capacitance testing mechanism is used to detect the capacitance value of the PTC thermistor to generate capacitance detection information.

[0010] As a further preferred embodiment, the system also includes a pulse testing mechanism, which is disposed in the second transmission path and is used to apply a transient pulse voltage to the PTC thermistor to detect its dynamic response characteristics.

[0011] As a further preferred embodiment, the system also includes a rejection and storage device, which is located next to the secondary unit and is used to reject and temporarily store substandard PTC thermistors detected by the multi-level detection device.

[0012] As a further preferred embodiment, the system includes a robot loading device, which is located at the loading station and is used to load materials onto the conveying device.

[0013] As a further preferred embodiment, the system also includes a packaging unit located downstream of the grading and feeding device along the conveying direction of the conveying device.

[0014] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: This application's automated testing and grading system for PTC thermistors employs a unique pipeline layout and multi-level detection mechanism, achieving fully automated operation from material loading, multiple tests, rejection, to grading and unloading, significantly improving testing efficiency. In particular, this system incorporates multiple detection stages, including withstand voltage testing, Rmin detection, infrared imaging, capacitance detection, and pulse detection, with specific settings for the process location and material flow arrangement of each stage. This constructs a three-dimensional conveying network composed of multi-branched conveyor paths and vertical conveyor circulation, enabling efficient and accurate flow of PTC thermistors between testing units. This avoids the lengthy paths and waiting times associated with traditional linear layouts, achieving efficient testing and grading of PTC thermistors and ensuring comprehensive control over all electrical and thermal performance indicators. Furthermore, by configuring the entire system with two switchable return conveyor paths, this application achieves parallel processing of the testing process, reducing the system's empty test rate and significantly improving capacity utilization. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of an automatic testing and grading system for PTC thermistors provided in an embodiment of this application; Figure 2This is an arrangement diagram of the R25 detection device, rejection and replenishment device, and conveying device provided in the embodiments of this application; Figure 3 This is a layout diagram of the main conveyor and the lifting and translating machine provided in the embodiments of this application; Figure 4 This is a layout diagram of the conveying device and multi-stage detection device provided in the embodiments of this application.

[0016] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1. Conveying Device; 1-1. Main Conveyor; 1-1a. Upper Conveying Section; 1-1b. Lower Return Section; 1-2. Branch Conveyor; 1-3. Auxiliary Conveyor; 1-4. Lifting and Shifting Machine; 1-5. Lifting and Rotating Machine; 2. R25 Detection Device; 2-1. R25 Initial Inspection Unit; 2-2. R25 Re-inspection Unit; 3. Rejection and Replenishment Device; 3-1. Gripping Mechanism; 3-2. Temporary Storage Mechanism for Substandard Products; 3-3. Temporary Storage Mechanism for Standard Products; 4. Multi-stage Detection Device; 4-1. Withstand Pressure Mechanism; 4-2. Temperature Regulation Mechanism; 4-3. Rmin Testing Mechanism; 4-4. Infrared Imaging Mechanism; 4-5. Capacitance Testing Mechanism; 5. Appearance Inspection Device; 6. Segmented Feeding Device; 7. Pulse Testing Mechanism; 8. Rejection Temporary Storage Device; 9. Robot Feeding Device; 10. Packaging Unit; 11. Material Tray. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0018] The following is in conjunction with the appendix Figures 1-4 This application will be described in further detail.

[0019] This application discloses an automatic testing and grading system for PTC thermistors. (Refer to...) Figure 1The automatic testing and grading system for PTC thermistors includes a conveying device 1, an R25 detection device 2, a rejection and replenishment device 3, a multi-stage detection device 4, an appearance inspection device 5, a grading and unloading device 6, and a control module. The system is equipped with a loading station and a first conveying path and a second conveying path. The R25 detection device 2 includes an R25 initial inspection unit 2-1 and an R25 re-inspection unit 2-2. The multi-stage detection device 4 includes multiple primary units and multiple secondary units. The control module is electrically connected to each device to control the system's conveying path switching and test grading. In the first conveying path, the conveying device 1 first transports the tray 11 containing PTC thermistors from the loading station to the R25 initial inspection unit 2-1 for R25 initial inspection. Then, the rejection and replenishment device 3 removes PTC thermistors from the tray 11 that fail the R25 initial inspection and temporarily stores the PTC thermistors that pass the initial inspection. Finally, the empty tray 11 returns to the loading station. In the second conveying path, the conveying device 1 sequentially sends multiple trays 11 containing PTC thermistors from the loading station to the R25 initial inspection unit 2-1 for inspection; then the rejection and replenishment device 3 removes PTC thermistors that exceed the standard and replenishes the trays 11 with temporarily stored PTC thermistors; next, the multiple trays 11 are first transferred to the R25 re-inspection unit 2-2 for R25 re-testing, then diverted to multiple primary units for PTC thermistor withstand voltage test and Rmin test, then transferred to multiple secondary units for temperature test and capacitance test, then converged to the appearance inspection device 5 for appearance inspection, and finally transferred to the sorting and unloading device 6; the control module controls the sorting and unloading device 6 to sort the PTC thermistors according to the test results of each testing device, and the empty trays 11 after sorting are returned to the loading station.

[0020] As a preferred option, such as Figure 2 and Figure 3 As shown, the conveying device 1 includes a main conveyor 1-1, branch conveyors 1-2, auxiliary conveyors 1-3, lifting and translating machines 1-4, and lifting and rotating machines 1-5. Multiple main conveyors 1-1 are arranged sequentially in the same direction, including an upper conveying section 1-1a and a lower return section 1-1b, which are arranged vertically with opposite conveying directions. The upper conveying section 1-1a is used to convey trays 11 containing PTC thermistors, and the lower return section 1-1b is used to return empty trays 11. Multiple lifting and translating machines 1-4 are provided for transferring trays 11 between adjacent main conveyors 1-1 and for transferring trays 11 between the upper conveying section 1-1a and the lower return section 1-1b, thus forming a vertical conveying cycle including a first conveying path.

[0021] Among them, such as Figure 4As shown, multiple branch conveyors 1-2 are arranged side by side. One end of each branch conveyor 1-2 is connected to the upper conveying section 1-1a of the main conveyor 1-1 via a lifting and indexing machine 1-5, and the other end is connected to the auxiliary conveyor 1-3 via another lifting and indexing machine 1-5, thus forming a multi-branch conveying path. This multi-branch conveying path, in conjunction with the vertical conveyor cycle, forms a second conveying path. It can be understood that these devices cooperate to form an assembly line, in which a loading station is set up at the upper conveying section 1-1a of the main conveyor 1-1 at the beginning of the assembly line.

[0022] Preferably, the lifting and shifting machine 1-4 is divided into a middle lifting and shifting machine 1-4 and an end lifting and shifting machine 1-4. The middle lifting and shifting machine 1-4 is connected in series between adjacent main conveyors 1-1, and at least one middle lifting and shifting machine 1-4 is located after the R25 re-inspection unit 2-2 and before the multi-stage detection device 4. The middle lifting and shifting machine 1-4 can transfer empty trays 11 from the upper conveying section 1-1a to the lower return section 1-1b, so that the empty trays can be quickly returned to the loading station through the lower return section 1-1b, thereby improving the circulation efficiency. At the same time, the middle lifting and shifting machine 1-4 can transfer the trays 11 in the upstream main conveyor 1-1 to the downstream main conveyor 1-1, so as to realize the smooth flow of the trays 11.

[0023] The lifting and shifting machine 1-4 at the end point is located at the end of the overall structure composed of multiple main conveyors 1-1. Located at the end of the inspection process, the lifting and shifting machine 1-4 can transfer the material tray 11 that has completed inspection in the second conveying path from the upper conveying section 1-1a to the lower return section 1-1b, realizing efficient return of empty trays. Located at the beginning of the inspection process, the lifting and shifting machine 1-4 can transfer the empty material tray 11 upwards so that the material tray 11 can flow to the loading station for loading, forming a circular flow of the material tray 11.

[0024] As a preferred option, such as Figure 4 As shown, auxiliary conveyors 1-3 are arranged side-by-side with main conveyor 1-1. Multiple branch conveyors 1-2 are arranged side-by-side between main conveyor 1-1 and auxiliary conveyor 1-3. The conveying direction of branch conveyors 1-2 is perpendicular to the conveying direction of main conveyor 1-1. One end of multiple branch conveyors 1-2 on the same side is connected to the upper conveyor section 1-1a via a lifting and rotating machine 1-5, forming a 90-degree turning conveyor. The other end on the same side is connected to auxiliary conveyor 1-3 via another lifting and rotating machine 1-5, also forming a 90-degree turning conveyor, thus forming a multi-branch conveying path. At the same time, this multi-branch conveying path, in conjunction with the vertical conveying cycle, forms a second conveying path. Under this design, through spatial three-dimensional layout and multi-machine collaboration, feeding, detection, diversion, convergence, and return are orderly connected, significantly improving efficiency while ensuring detection accuracy.

[0025] It is understandable that in the multi-branch conveying path, the branch conveyor 1-2 is divided into the inflow branch conveyor 1-2 and the return branch conveyor 1-2; with the conveying direction of the main conveyor 1-1 as the reference, the inflow branch conveyor 1-2 is located upstream of the return branch conveyor 1-2. In the entire system, after the PTC thermistor in the material tray 11 completes the R25 retest, under the control of the control module, multiple batches of material trays 11 are diverted by multiple lifting and indexing machines 1-5 and flow into multiple inlet branch conveyors 1-2 to achieve multi-path diversion detection. After the withstand voltage test and Rmin test are completed at the inlet branch conveyor 1-2, the material tray 11 is transferred to the auxiliary conveyor 1-3 by the lifting and indexing machine 1-5, and then transferred to the return branch conveyor 1-2 by the auxiliary conveyor 1-3 and the lifting and indexing machine 1-5 for temperature test and capacitance test. After the test is completed, the lifting and indexing machine 1-5 turns the material tray 11 90 degrees and re-enters it into the upper conveying section 1-1a of the main conveyor 1-1 to enter the next process.

[0026] Preferably, in some embodiments, there are 8 branch conveyors 1-2 for inflow and 2 branch conveyors 1-2 for return. It is understood that in some other embodiments, the number of branch conveyors 1-2 for inflow and branch conveyors 1-2 for return can be dynamically adjusted according to actual capacity requirements, for example, in high-load operation scenarios, it can be expanded to a configuration of 12 inflow and 3 return.

[0027] Preferably, in some embodiments, the main conveyor 1-1, the branch conveyor 1-2 and the auxiliary conveyor 1-3 include, but are not limited to, double-speed chain conveyors (such as metering and calibration double-speed chains). Double-speed chain conveyors have the advantages of stable operation, high positioning accuracy and strong load-bearing capacity, and are suitable for multi-station synchronous detection and high-speed flow scenarios. The double-speed chain conveyor is equipped with check valves, limiters and position sensors to cooperate with the control module to control the precise conveying and positioning of the material tray 11.

[0028] Preferably, in some embodiments, the lifting and transferring machine 1-4 includes, but is not limited to, a lifting conveyor, and the lifting and indexing machine 1-5 includes, but is not limited to, a chain-type lifting and transferring machine. In some embodiments, the lifting and transferring machine 1-4 and the lifting and indexing machine 1-5 preferably employ servo drives, in conjunction with sensors to achieve precise positioning, ensuring that the transfer of the material tray 11 between different conveying paths is free from deviation and collision. The main conveyor 1-1, branch conveyor 1-2, auxiliary conveyor 1-3, lifting and transferring machine 1-4, and lifting and indexing machine 1-5 are existing equipment, and their structural composition will not be described in detail here.

[0029] Preferably, in some embodiments, the tray 11 has 49 material compartments arranged in an array of 7 rows and 7 columns. Each material compartment has an opening at the top and a hollowed-out bottom, and each material compartment can accommodate one PTC thermistor. The tray 11 is provided with positioning notches and mistaken-proof markings around its perimeter to ensure accurate positioning and unique orientation during transport. Of course, in other embodiments, the number of material compartments can be adjusted to other row and column combinations according to actual needs, and the layout of the positioning notches and mistaken-proof markings can be adapted accordingly to ensure compatibility with other conveying equipment. It is understood that the number of material compartments on the tray 11 can be flexibly configured according to the production line cycle and testing process requirements to match the batch testing requirements of PTC thermistors of different specifications.

[0030] Furthermore, such as Figure 1 As shown, in some embodiments, the system further includes a rejection storage device 8, which is located beside the secondary unit and is used to reject and temporarily store substandard PTC thermistors detected by the multi-level detection device 4. Preferably, the rejection storage device 8 is equipped with an independent buffer area, supports storage by defect type, and has a full-material warning function; when the buffer area capacity reaches a threshold, the system automatically triggers an alarm to prompt manual intervention. Preferably, the rejection storage device 8 is located between two adjacent branch conveyors 1-2 for return flow, realizing centralized buffering and classified management of defective products (substandard PTC thermistors) detected by the two adjacent secondary units, improving the cleanliness of the production line and traceability efficiency.

[0031] Furthermore, in some embodiments, the purpose of setting up the R25 detection device 2 and the rejection and replenishment device 3 is to simultaneously measure the zero-power resistance value of multiple PTC thermistors on each material tray 11, ensure that the PTC thermistors within the preset resistance range remain on the material tray 11, reject PTC thermistors that exceed the range, and store the numerical value of the R25 test result of the PTC.

[0032] Specifically, such as Figure 2As shown, the R25 detection device 2 includes an R25 initial inspection unit 2-1 and an R25 re-inspection unit 2-2. The R25 initial inspection unit 2-1 and the R25 re-inspection unit 2-2 are arranged at intervals on the main conveyor 1-1, while the rejection and replenishment device 3 is set between the R25 initial inspection unit 2-1 and the R25 re-inspection unit 2-2. The R25 initial inspection unit 2-1 is used to perform the initial R25 detection on the PTC thermistor in the material tray 11 and generate the initial R25 detection information. The control module can receive and analyze the initial R25 detection information, and control the rejection and replenishment device 3 to reject, replenish and temporarily store the PTC thermistor in the material tray 11 based on the analysis results. The R25 re-inspection unit 2-2 is used to perform a second R25 inspection on the material tray 11 after the material has been rejected and replenished, and to generate second R25 inspection information. The control module receives the second R25 inspection information and uses the second inspection information as one of the inspection results for subsequent sorting and unloading of PTC thermistors.

[0033] Preferably, in some embodiments, the R25 initial inspection unit 2-1 and the R25 re-inspection unit 2-2 measure the zero-power resistance of the PTC thermistor under a constant temperature of 25±2℃ with a voltage of 1.5V. The R25 measurement circuit adopts a four-wire connection method to effectively eliminate the influence of lead resistance on the measurement results.

[0034] Preferably, in some embodiments, when the R25 initial inspection unit 2-1 completes the testing of the PTC thermistors and removes PTC thermistors with excessive resistance values, the excessive resistance values ​​are further subdivided into categories. Specifically, excessively high resistance values ​​(generally around 5%) are further divided into two categories according to a preset refined resistance value range, and excessively low resistance values ​​(around 10%) are further divided into three categories according to a preset refined resistance value range. The allowable resistance range and the related refined resistance value range categories can be adjusted according to requirements, so that the boundaries and categories of excessively high and excessively low resistance values ​​can be controlled according to needs.

[0035] Among them, PTC thermistors that fail the initial inspection (i.e., PTC thermistors with excessively high or low resistance values) are removed from the replenishment device 3 and stored. These thermistors are not defective products, but their surfaces must not be scratched. That is, PTC thermistors with excessively high or low resistance values ​​that are not scratched can be recycled to the loading station for secondary use, thereby improving material utilization and reducing production costs.

[0036] As a preferred option, such as Figure 2As shown, in some embodiments, the rejection and replenishment device 3 includes a gripping mechanism 3-1, a non-compliant product temporary storage mechanism 3-2, and a compliant product temporary storage mechanism 3-3. The gripping mechanism 3-1 is used to pick up, place, and transfer PTC thermistors on the material tray 11 in the upper conveyor section 1-1a. The gripping mechanism 3-1 preferably includes a multi-axis robotic arm and a vacuum suction cup. The vacuum suction cup installed at the end of the multi-axis robotic arm enables precise adsorption, gripping, and placement of the PTC thermistors, ensuring stable gripping without damaging the surface of the PTC thermistors. The non-compliant product temporary storage mechanism 3-2 and the compliant product temporary storage mechanism 3-3 are respectively located on both sides of the upper conveyor section 1-1a. Both the non-compliant product temporary storage mechanism 3-2 and the compliant product temporary storage mechanism 3-3 preferably include a receiving box.

[0037] After the initial R25 inspection by unit 2-1, the unit transmits the initial R25 inspection information to the control module. The upper conveyor section 1-1a then transports the tray 11, which has undergone the initial R25 inspection, to the rejection and replenishment station. The control module generates control commands based on the initial inspection information, controlling the gripping mechanism 3-1 to remove PTC thermistors with excessive resistance from tray 11 and transfer them to the non-compliant product storage mechanism 3-2. Then, the gripping mechanism 3-1 replenishes the PTC thermistors in the compliant product storage mechanism 3-3 to the empty PTC thermistor slots. The entire process is monitored in real-time by sensors to ensure accurate operation. After replenishment, tray 11 continues to be transported to the R25 re-inspection unit 2-2 for re-inspection. The secondary inspection data is uploaded to the control module for final grading, achieving closed-loop management throughout the entire process.

[0038] Generally, the over-standard temporary storage mechanism 3-2 has independent partitions for storing over-standard PTC thermistors with different resistance ranges to avoid mixing. Each partition is equipped with an identification tag, which, together with the control module, enables automatic storage and retrieval and inventory record updates. Under the command of the control module, the grabbing mechanism 3-1 removes the over-standard PTC thermistors from the material tray 11 and places them into the designated partitions in the over-standard temporary storage mechanism 3-2, and removes the non-over-standard PTC thermistors from the compliant temporary storage mechanism 3-3 and replenishes the empty spaces in the material tray 11, ensuring continuous material supply and accurate grading.

[0039] When the number of qualified PTC thermistors in the qualified product storage mechanism 3-3 falls below a set threshold, the system triggers a replenishment warning and switches the operating path from the second conveying path to the first conveying path to replenish the number of qualified PTC thermistors in the qualified product storage mechanism 3-3. After the tray is empty and the number of qualified PTC thermistors has been replenished to above the set threshold, the empty tray 11 is returned, and then the system automatically switches back to the second conveying path.

[0040] Furthermore, such as Figure 4As shown, multiple primary units are mounted one-to-one above the branch conveyors 1-2 for inflow to perform withstand voltage tests and Rmin tests on the PTC thermistors in the inflow tray 11. Multiple secondary units are mounted one-to-one on the branch conveyors 1-2 for return to perform temperature tests and capacitance tests on the PTC thermistors in the return tray 11.

[0041] Furthermore, in some embodiments, the primary unit is configured to perform the following functions: 1. Each PTC thermistor is subjected to three withstand voltage tests (preferably in the form of gradually increasing voltage, such as using 850V, 1200V, and 1400V for gradual withstand voltage testing), or other withstand voltage tests are performed. PTC thermistors with a residual current trend of increasing in the positive direction are rejected.

[0042] 2. Store the It curve generated by the withstand voltage test, and discard PTC thermistors that generate irregular curves.

[0043] 3. PTC thermistors that meet the thermal imaging temperature standard are rejected.

[0044] 4. Measure and record the Rmin value of the PTC thermistor under the preset maximum voltage (Vmax) and at 70℃ or other target temperatures, striving to achieve zero error (PPM=0) in the accuracy of the Rmin test.

[0045] Specifically, such as Figure 4 As shown, in some embodiments, the primary unit includes a pressure-resistant mechanism 4-1, a temperature regulating mechanism 4-2, and an Rmin testing mechanism 4-3. The pressure-resistant mechanism 4-1, the temperature regulating mechanism 4-2, and the Rmin testing mechanism 4-3 are arranged sequentially along the conveying direction of their respective branch conveyors 1-2, forming a pressure-resistant testing station, a temperature regulating station, and an Rmin testing station.

[0046] Among them, the withstand voltage mechanism 4-1 is used to apply test voltage to the PTC thermistors in the tray 11 in batches to detect the insulation performance of the PTC thermistors; the temperature adjustment mechanism 4-2 is used to adjust the temperature of the PTC thermistors in the tray 11 so that the temperature of the PTC thermistors reaches the preset room temperature range; the Rmin test mechanism 4-3 is used to test the minimum resistance value of the PTC thermistors under room temperature conditions.

[0047] For the withstand voltage testing mechanism 4-1, as a preferred embodiment, in some specific embodiments, the upper limit of the withstand voltage in the withstand voltage testing mechanism 4-1 is preferably 1500V. Of course, it can be adjusted according to the requirements to achieve higher or lower voltages. In the withstand voltage testing stage, an IGBT power control switch is preferably used to ensure timely response. During the withstand voltage testing process, the withstand voltage testing mechanism 4-1 is equipped with an anti-sparking structure and a power-on / off mechanism, so that each upper and lower contact in the withstand voltage testing mechanism 4-1 will not generate artificial "sparking" on the PTC thermistor electrode, and there is no "sparking" risk in the structural design and power-on / off design logic of the upper and lower contacts. Specifically, in some embodiments, a universal structure is used to ensure that the contacts and the PTC thermistor achieve surface contact to eliminate the risk of sparking. Furthermore, during the withstand voltage test, there must be at least a certain delay before power-on and power-off to ensure that the contacts and the PTC thermistor are in complete contact or disconnection. This delay can be flexibly set according to actual needs, and will not be elaborated further here.

[0048] Furthermore, in some embodiments, during the withstand voltage test, the control module records the residual current (steady-state current) of each PTC thermistor and stores the response curve distribution of each PTC thermistor at Vmax voltage (It). Since qualified products will generally show a standard curve distribution in the aforementioned response curve distribution graph, while unqualified products will exhibit abnormal curves deviating from the standard distribution (e.g., defective products caused by impurity diffusion and surface contamination will show abnormal characteristic values ​​in the curve graph), this situation is automatically identified and marked by the control module, simultaneously triggering the sorting mechanism to isolate the unqualified products to a designated area. Additionally, during the withstand voltage test, the voltage corresponding to VBD being a preset multiple of the residual current value is measured. When the current exceeds the preset multiple, the power is immediately cut off, and the PTC thermistor is determined by the control module to be a defective product and discarded in subsequent processes.

[0049] Furthermore, in some embodiments, the withstand voltage mechanism 4-1 is provided with a protection mechanism to prevent the occurrence of surge short-circuit current and high-potential intrusion.

[0050] Furthermore, in some extreme cases, PTC thermistors may be missed during the withstand voltage test. These missed products can be automatically identified and marked as abnormal (not directly considered defective) by the control module based on the characteristic of not having recorded withstand voltage test data. Simultaneously, they are isolated to a designated area by the subsequent rejection and temporary storage device 8 to prevent them from flowing into subsequent processes. Under the detection and control of relevant control modules and sensors, the entire process has a visual process monitoring function, which can display the position of the missed PTC thermistors on the material tray 11 on the screen. In some extreme cases, arcing or short circuits may occur during the withstand voltage test. In this case, the protection mechanism will be activated immediately, the control module will determine that the PTC thermistor at that location is defective, and it will be rejected by the subsequent sorting mechanism, with the fault information recorded.

[0051] Furthermore, regarding the temperature regulation mechanism 4-2, in some embodiments, the temperature regulation mechanism 4-2 includes a temperature regulating device and a temperature detection device. The temperature regulating device, for heating, includes but is not limited to using resistance wire heating devices, light heating devices, hot air devices, or semiconductor temperature control devices to achieve temperature rise; for cooling, it includes but is not limited to using heat sinks, fans, or cooling coils. The temperature detection device collects temperature data of the environment and the target area in real time and feeds the information back to the control module, which dynamically adjusts the working state of the temperature regulating device to ensure that the temperature remains stable within the set range. After detecting that the overall temperature of many PTC thermistors in the material tray 11 has reached the set threshold, the system automatically enters the constant temperature maintenance stage to ensure that each element is heated evenly and without overshoot, providing a stable and accurate constant temperature environment for the downstream Rmin detection process. The specific structure of the temperature regulation mechanism 4-2 is not shown in the accompanying drawings, but only partially. Figure 4 In the top view shown, the location of the device is indicated by a dashed box. In some specific embodiments, the temperature regulating mechanism 4-2 can be a constant temperature oven with a lower hood that can be raised and lowered for adjustment.

[0052] Furthermore, for the Rmin testing mechanism 4-3, the Rmin test of the PTC thermistor is performed in a constant temperature controlled environment by applying a very small test current through components such as a four-wire measurement circuit and a micro current source. The PTC thermistor is fixed and contacted by an insulating clamp with the upper and lower contacts, and the minimum resistance value of the PTC thermistor in the zero power state at room temperature is measured.

[0053] Preferably, in some embodiments, the Rmin test mechanism 4-3 employs an IGBT power control switch to ensure timely response. The upper and lower contacts in the Rmin test mechanism 4-3 are made of materials that are high temperature resistant, wear-resistant, durable, not easily deformed, and highly conductive, so that the contact resistance value is close to zero. Preferably, the upper and lower contacts of Rmin are probes with sufficiently small resistance or a defined resistance value.

[0054] Furthermore, temperature sensors are installed at points 4-3 of the Rmin testing mechanism to detect the surface temperature of each PTC thermistor in real time, ensuring that Rmin is measured within the preset range. In this step, it should be ensured that every PTC thermistor undergoes the Rmin test. Considering that in extreme cases, some PTC thermistors may be missed due to failing to meet the temperature standard (not completing the Rmin test within the preset temperature range during the Rmin test) or other reasons, the system determines that these PTC thermistors are not considered defective and will be removed and placed into a recycling box by the rejection storage device in subsequent steps. In this system, it is preferable to set up a visual monitoring module during the testing process, such as recording and displaying the position of the missed PTC thermistors on the material tray 11 on the screen for personnel observation.

[0055] In some embodiments, after measuring Rmin, the control module automatically calculates X = Rmin / R25 based on the test results, where 0.18 ≤ X ≤ 0.26 (the value can be input according to customer needs). If the X value exceeds the set range, the PTC thermistor parameter is determined to be abnormal, marked as a defective product, and the corresponding location information is recorded. The system uploads the test data to the cloud database in real time, supporting subsequent quality traceability and analysis. For qualified products, they continue to flow to the next process; unqualified products are automatically rejected at or after the sorting station. In addition, the control module also records a dynamic statistical distribution chart of Rmin for no more than a preset time period (e.g., 48 hours), which can be printed in real time so that on-site personnel can quickly grasp the production quality trend and adjust process parameters in a timely manner.

[0056] Furthermore, in some embodiments, after the Rmin test is completed, the control module automatically marks and classifies the PTC thermistors whose resistance values ​​exceed the limits (too high or too low). Typically, they are classified into two categories of defective products each for too low and too high resistance values, for a total of four categories. The subsequent rejection storage device 8 then temporarily stores these defective products into the corresponding recyclable boxes.

[0057] Furthermore, in some embodiments, the Rmin current detection sampling circuit uses two sets that work simultaneously. If the error between the two sets of measurements exceeds 3% for a number of consecutive times (the number of times can be set) at 70±2℃, a circuit fault can be determined. A standard resistor is used to verify whether the test circuit is accurate, ensuring that the Rmin value output data is close to zero defects.

[0058] Furthermore, in some embodiments, the secondary unit includes an infrared imaging mechanism 4-4 and a capacitance testing mechanism 4-5, with the infrared imaging mechanism 4-4 positioned upstream of the capacitance testing mechanism 4-5. The infrared imaging mechanism 4-4 includes, but is not limited to, employing an infrared imager to acquire real-time thermal distribution images of the PTC thermistor in the material tray 11 and generate temperature information. The control module determines whether the PTC thermistor's temperature meets the standard based on the temperature information and a preset acceptable temperature range. The capacitance testing mechanism 4-5 is used to detect the capacitance value of the PTC thermistor to generate capacitance detection information.

[0059] Furthermore, in some embodiments, the system also includes a pulse testing mechanism 7, which is disposed in the second conveying path and is used to apply transient pulse voltage to the PTC thermistor to detect its dynamic response characteristics. The location of the pulse testing mechanism 7 can be controlled according to requirements. For example, the pulse testing mechanism 7 is disposed on the branch conveyor 1-2 where the primary unit is located, along the conveying direction on the branch conveyor 1-2, after the withstand voltage mechanism 4-1 and before the temperature regulating mechanism 4-2; that is, the pulse test is performed after the withstand voltage mechanism 4-1 completes the withstand voltage test. Another example is that the pulse testing mechanism 7 is disposed on the branch conveyor 1-2 where the secondary unit is located, and is located before the infrared imaging mechanism 4-4. Alternatively, the pulse testing mechanism 7 is disposed on the main conveyor 1-1, and is located upstream of the branch conveyor 1-2. Alternatively, the pulse testing mechanism 7 is disposed on other conveying sections where it does not affect the test logic, ensuring that pulse response detection is completed synchronously during continuous production. Preferably, the voltage during the pulse test is a preset multiple of the voltage during the withstand voltage test. In the testing process, the pulse test mechanism 7 is preferably located after the withstand voltage mechanism 4-1 and before the temperature adjustment mechanism 4-2.

[0060] Understandably, to protect the production line and ensure temperature uniformity during testing, protective shields are installed within the production line. For branch conveyors 1-2 in the return conveyor path, this can be achieved as follows: Figure 1 The diagram shows that each branch conveyor 1-2 is equipped with an independent protective cover. Alternatively, as shown... Figure 4 The two branch conveyors 1-2 are brought together and then a connected protective cover is installed. The matching material rejection temporary storage device 8 can be installed inside the connected protective cover, or it can be flexibly arranged in other locations as needed.

[0061] Furthermore, such as Figure 1As shown, in some embodiments, the appearance inspection device 5 is located downstream of the second inspection unit and connected in series between two adjacent main conveyors 1-1. The appearance inspection device 5 is used to receive the material tray 11 conveyed by the upstream main conveyor 1-1, perform appearance inspection on the PTC thermal element therein, and transmit the inspection result to the control module in real time for judgment. Then, the inspected material tray 11 is sent to the downstream main conveyor 1-1 to continue to flow.

[0062] Preferably, the appearance inspection device 5 uses photographic imaging (such as CCD appearance inspection) to inspect the appearance of the PTC thermistor on all six sides. The control module determines whether the PTC thermistor has defects such as cracks, defects, or contamination based on a preset image recognition algorithm and imaging results, and generates appearance inspection information. When a defect is detected, the system automatically marks the component and records the defect type and location. Defective products are then sorted into the non-conforming product area's material box at the subsequent sorting and unloading device 6. The sorting and unloading device 6 includes, but is not limited to, existing material sorting machine modules and indexing plates.

[0063] Furthermore, in some embodiments, the control module automatically sorts the PTC thermistors based on multi-dimensional data such as R25 retest value, Rmin value, capacitance value, infrared imaging information, pulse response information, and appearance inspection information, according to a preset grade division database. It then drives the graded feeding device 6 to place the PTC thermistors of the corresponding grade into the corresponding material boxes, thereby achieving accurate graded sorting and quality traceability of the PTC thermistors. The sorting results are uploaded to the MES system in real time, and the test data of each PTC thermistor is bound to a unique serial number.

[0064] Furthermore, such as Figure 1 , Figure 2 As shown, in some embodiments, the system includes a robotic loading device 9 located at the loading station. The robotic loading device 9 automatically grabs materials and places them in the upper conveyor section 1-1a of the main conveyor 1-1 to achieve efficient and stable loading operations. Two or more sets of robotic loading devices 9 may be provided. For convenient loading, a conveying device (such as a belt conveyor) can be installed below the robotic loading device 9. The material to be tested (PTC thermistor) is placed onto the belt by a person or a grabbing device, and after being transported by the belt to the grabbing range of the robotic loading device 9, the robotic loading device 9 loads the material into the material tray 11 of the conveyor 1. Preferably, before loading, the PTC thermistor to be tested needs to be stored in a constant temperature chamber at 25°C for 12 hours.

[0065] Furthermore, in some embodiments, the system further includes a packaging unit 10, located downstream of the grading and feeding device 6. The packaging unit 10 includes, but is not limited to, a labeling machine. When the packaging unit 10 includes a labeling machine, the labeling machine is used to print QR code labels on the outer packaging of qualified material boxes. The QR code contains information such as product model, batch number, production date, and grading level, enabling product information traceability. Furthermore, in some embodiments, the system further includes inspection mechanisms located after each testing process. These inspection mechanisms automatically inspect the PTC thermistors circulating in the system based on pre-prepared standard resistance samples.

[0066] Furthermore, in some embodiments, after labeling, a VGA robot transports the material boxes to a manual station, where a worker scans the QR code once, issuing an updated QR code label. After multiple material boxes of the same grade are combined and packaged, the updated QR code label is affixed to the final package. Under this design, the entire automated testing and grading system can achieve a qualified product capacity of 10,000 pieces / hour, exhibiting extremely high batch production efficiency.

[0067] It should be understood that expressions such as "comprising" and "may include" used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof. Structures, mechanisms, etc., not specifically described in this application can be selected from standard modules commonly used in the prior art, and therefore are not elaborated upon.

[0068] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application 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 application.

[0069] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0070] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0071] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An automatic testing and grading system for PTC thermistors, characterized in that, The system includes a conveying device (1), an R25 detection device (2), a rejection and replenishment device (3), a multi-stage detection device (4), an appearance inspection device (5), a graded unloading device (6), and a control module. The system is equipped with a loading station and a first conveying path and a second conveying path, wherein: The R25 testing device (2) includes an R25 initial testing unit (2-1) and an R25 retesting unit (2-2). The multi-level testing device (4) includes multiple primary units and multiple secondary units. The control module is electrically connected to each device to control the switching of the system's transport path and the test classification. In the first conveying path, the conveying device (1) first conveys the tray (11) containing PTC thermistors from the loading station to the R25 initial inspection unit (2-1) for R25 initial inspection; then the rejection and replenishment device (3) rejects the PTC thermistors in the tray (11) that exceed the R25 initial inspection standard, and temporarily stores the PTC thermistors that pass the initial inspection standard; the empty tray (11) is returned to the loading station; In the second conveying path, the conveying device (1) sequentially sends multiple trays (11) containing PTC thermistors from the loading station to the R25 initial inspection unit (2-1) for inspection; then the rejection and replenishment device (3) rejects the PTC thermistors that exceed the standard and replenishes the trays (11) with the temporarily stored PTC thermistors; then the multiple trays (11) are first transferred to the R25 re-inspection unit (2-2) for R25 re-testing, then diverted to multiple first-level units for PTC thermistor withstand voltage test and Rmin test, then transferred to multiple second-level units for temperature test and capacitance test, then converged to the appearance inspection device (5) for appearance inspection, and finally transferred to the sorting and unloading device (6); the control module controls the sorting and unloading device (6) to sort the PTC thermistors according to the test results of each inspection device, and the empty trays (11) after sorting are returned to the loading station.

2. The automatic testing and grading system as described in claim 1, characterized in that, The conveying device (1) includes a main conveyor (1-1), a branch conveyor (1-2), an auxiliary conveyor (1-3), a lifting and translating machine (1-4), and a lifting and indexing machine (1-5), wherein: The main conveyor (1-1) has multiple sections arranged sequentially in the same direction, including an upper conveying section (1-1a) and a lower return section (1-1b); Multiple lifting and translating machines (1-4) are provided for transferring the material trays (11) between two adjacent main conveyors (1-1) and between the upper conveying section (1-1a) and the lower return section (1-1b); Multiple branch conveyors (1-2) are arranged side by side. The two ends of the branch conveyors (1-2) are connected to the upper conveyor section (1-1a) and the auxiliary conveyor (1-3) respectively through the lifting and indexing machine (1-5).

3. The automatic testing and grading system as described in claim 1, characterized in that, The rejection and replenishment device (3) includes: The gripping mechanism (3-1) is used to pick up, place and transfer the PTC thermistor on the tray (11); The substandard temporary storage mechanism (3-2) is used to store PTC thermistors that exceed the R25 detection limit and are taken out by the gripping mechanism (3-1); The qualified product storage mechanism (3-3) is used to temporarily store the PTC thermistors that have passed the R25 test and have been taken out by the gripping mechanism (3-1).

4. The automatic testing and grading system as described in claim 1, characterized in that, The primary unit includes a pressure resistance mechanism (4-1), a temperature regulation mechanism (4-2), and an Rmin testing mechanism (4-3), wherein: The withstand voltage mechanism (4-1) is used to apply a test voltage to the PTC thermistor in the tray (11) to detect the insulation performance of the PTC thermistor. The temperature regulation mechanism (4-2) is used to regulate the temperature of the PTC thermistor in the tray (11) so that the temperature of the PTC thermistor in the tray (11) reaches the preset room temperature range. The Rmin test mechanism (4-3) is used to test the minimum resistance value of the PTC thermistor under normal temperature conditions.

5. The automatic testing and grading system as described in claim 1, characterized in that, The secondary unit includes an infrared imaging mechanism (4-4) and a capacitance testing mechanism (4-5), wherein: The infrared imaging mechanism (4-4) is used to collect real-time heat distribution images of the PTC thermistor in the tray (11) and generate temperature information. The control module is used to determine whether the temperature of the PTC thermistor meets the standard based on the temperature information and the preset temperature qualified range. The capacitance testing mechanism (4-5) is used to detect the capacitance value of the PTC thermistor to generate capacitance detection information.

6. The automatic testing and grading system as described in any one of claims 1-5, characterized in that, The system also includes a pulse testing mechanism (7), which is disposed in the second transmission path and is used to apply a transient pulse voltage to the PTC thermistor to detect its dynamic response characteristics.

7. The automatic testing and grading system as described in any one of claims 1-5, characterized in that, The system also includes a rejection storage device (8), which is located next to the secondary unit and is used to reject and temporarily store substandard PTC thermistors detected by the multi-level detection device (4).

8. The automatic testing and grading system as described in any one of claims 1-5, characterized in that, The system also includes a robot loading device (9), which is located at the loading station and is used to load the conveying device (1).

9. The automatic testing and grading system as described in any one of claims 1-5, characterized in that, The system also includes a packaging unit (10), which is located downstream of the grading and feeding device (6) along the conveying direction of the conveying device (1).

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