A heat shrink tube heating apparatus

Abstract

The utility model belongs to the technical field of pencil production equipment, concretely is a kind of heat shrink tube heating equipment, including operation mesa, hot air chamber is equipped on operation mesa, heating piece is equipped in hot air chamber, heating piece is connected temperature controller by alternating current contactor, one side wall of hot air chamber is equipped with return air inlet and air outlet, the position of hot air chamber close to air outlet is equipped with temperature sensor for monitoring the temperature of hot air chamber, temperature sensor is connected with temperature controller signal, air outlet is connected blowing opening by hot air pipeline, pipeline fan is external in hot air chamber, pipeline fan front and back two sides are connected with return air pipeline and return air inlet respectively, temperature sensor linkage temperature controller, dynamic regulation heating piece;Pipeline fan always open maintains continuous circulation, avoids start-stop fluctuation, blowing opening directional air supply, return air inlet recycles waste heat, pipeline fan integrally realizes blowing / return air, waste heat recycling, operation mesa design optimizes loading space;Hot air chamber temporarily stores mixed gas, and temperature uniformity is better than hot air gun.

Description

Technical Field

[0001] This utility model belongs to the technical field of wire harness production equipment, specifically a heat shrink tubing heating device. Background Technology

[0002] Heat shrink tubing is a specially designed heat shrink sleeve made of polyolefin material, typically EVA, which features high-temperature shrinkage, flexibility, flame retardancy, insulation, and corrosion resistance. Heat shrink tubing is widely used for insulation protection of various wire harnesses, solder joints, and inductors, as well as for rust and corrosion prevention of metal tubes and rods. Currently, heat shrink tubing is extensively used in the production process of wire harnesses to achieve insulation and corrosion protection at wire harness connections.

[0003] In actual production, when two or more wires are connected, heat shrink tubing can be used to cover the joint between the two wires. The heat shrink tubing contains adhesive. When the heat shrink tubing is heated to the indicated temperature, its diameter will shrink, and the adhesive will melt and then solidify to achieve insulation and corrosion protection at the wire connection.

[0004] To ensure consistent processing quality of heat shrink tubing, hot air blowers are currently widely used. During operation, the heat shrink tubing is conveyed into a heated furnace via a conveyor belt and then removed after a period of time. However, due to limitations in the performance of the heat shrink tubing itself and factors such as the external ambient temperature, the furnace temperature setting can vary, making it difficult to meet the processing requirements. Furthermore, the heat shrink tubing cannot be reheated, leading to an increased scrap rate. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this utility model provides a heat shrink tubing heating device with a simple structure and convenient use. It connects a thermocouple and a temperature controller via a heating element such as a heating wire, and sets a target temperature threshold through the temperature controller to ensure that the temperature of the blown hot air meets the requirements. This avoids the situation where the processing effect of the heat shrink tubing cannot be monitored in real time in the furnace of the hot air blower, thus solving the problems mentioned in the background technology.

[0006] This utility model provides the following technical solution: a heat shrink tubing heating device, including an operating table, a hot air chamber on the operating table, the hot air chamber having a hollow structure, a heating element inside the hot air chamber, the heating element being connected to a temperature controller via an AC contactor, a return air inlet and an air outlet on the side wall of the hot air chamber near the heat shrink tubing to be processed, the air outlet being on the upper part of the side wall of the hot air chamber, the return air inlet being on the lower part of the side wall of the hot air chamber, a temperature sensor for monitoring the temperature of the hot air chamber being located near the air outlet, the temperature sensor being signal-connected to the temperature controller, and the air outlet being connected to a blower via a hot air duct. A duct fan is externally mounted in the hot air chamber, located on the side wall of the hot air chamber, with its front and rear sides connected to the return air duct and the return air inlet, respectively.

[0007] The work surface is convenient for placing heat shrink tubing and retrieving the loading plate, providing ample operating space. An added hot air chamber temporarily stores and mixes the gas, resulting in more stable gas temperature, superior to a hot air gun. The heating element is connected to a temperature sensor and a temperature controller. The temperature controller sets a target temperature threshold to ensure the blown-out temperature meets the processing requirements of the heat shrink tubing. Based on the signal from the temperature sensor, the temperature controller controls the operation of the heating element. If the blown-out air temperature is below the target temperature threshold, the temperature controller instructs the heating element to heat; if the blown-out air temperature is above the target temperature threshold, the temperature controller instructs the heating element to stop heating. A duct fan enables both blowing and recirculation. Through the recirculation device, some hot air is reflected by the heat shrink tubing or naturally diffused before being drawn back into the hot air chamber through the recirculation duct. Hot air is directed towards the heat shrink tubing through the blower nozzle, and waste heat is recycled through the recirculation vent to save energy.

[0008] The heating element is an electric heating wire.

[0009] The temperature sensor is a thermocouple.

[0010] A one-way baffle is installed at the outer opening of the return air duct. This allows external air (including residual hot air) to enter the hot air chamber, but prevents hot air from leaking directly out through the return air duct. The one-way baffle can be a louver or a lightweight plastic sheet. Its lightweight design allows it to open easily with slightly stronger airflow, adding almost no load to the duct fan. The baffle automatically closes when the system stops to prevent backflow. The one-way baffle meets the backflow prevention requirement and has a simpler and more reliable structure. It eliminates the need for complex structures such as solenoid valves or one-way valves. The system does not have high airtightness requirements, and backflow is unlikely during continuous operation of the duct fan.

[0011] The power supply of the duct fan is always on, maintaining a continuous airflow without the need for frequent start-stop. The duct fan draws outside air through the return air duct to the heating element in the hot air chamber. At the same time, the duct fan also directs hot air from the hot air chamber to the heat shrink tubing through the air outlet, hot air duct, and blower.

[0012] The work surface has two air outlets: an upper outlet and a lower outlet. The upper outlet is located in the upper space of the work surface, and the lower outlet is located in the lower space. The upper and lower outlets are positioned opposite each other. The work surface has a slot at the processing location to allow the heat shrink tubing to receive airflow from both the upper and lower outlets. The horizontal distance between the air outlet and the return air inlet is greater than 10cm. If the return air inlet is too close to the air outlet, hot air may be drawn back before it even touches the heat shrink tubing.

[0013] The length of the slot is greater than the length of the processing area, which is the area where the batch of heat shrink tubing is laid flat. The width of the slot is greater than the width of the processing area to ensure that hot air blown from above and below can also flow from the side of the heat shrink tubing. The heat shrink tubing to be processed is clamped in the loading plate. The loading plate includes an upper plate and a lower plate. The length and width of the loading plate are greater than the slot. This is to facilitate placement on the workbench and to allow the long wire bundles at both ends of the heat shrink tubing to be exposed, thus preventing the wire bundles from bending. The upper plate and the lower plate can move relative to each other so that they can form a heat shrink tubing clamping space when closed and allow the heat shrink tubing to be put in and taken out when open. At least one side of the upper plate and the lower plate is provided with a mutually cooperating handle.

[0014] The lower plate has a mesh structure to support the heat shrink tubing. An upper plate is provided above the lower plate to limit the heat shrink tubing. The upper plate and the lower plate are rotatably connected at the ends away from the handheld part. The upper plate has a gap to allow hot air from the upper air outlet to pass through.

[0015] The lower plate has a mesh structure, and the upper plate consists of two symmetrical and independent clamping arms. The upper plate and the lower plate are rotatably connected on one side.

[0016] The operating table is provided with a positioning block at a corresponding position for positioning the feeding plate on the operating table.

[0017] Compared with existing technologies, this utility model has the following advantages: A temperature sensor linked to a temperature controller dynamically adjusts the heating element, ensuring stable hot air temperature that meets the requirements of heat shrink tubing; a duct fan maintains continuous circulation, avoiding start-stop fluctuations; the air outlet directs airflow, and the return air outlet recovers waste heat; the integrated duct fan achieves both blowing and returning air, and waste heat is recycled; a one-way baffle prevents backflow, and the structure is simple and reliable. The operating table design optimizes the material loading space; the hot air chamber temporarily stores the mixed gas, resulting in better temperature uniformity than a hot air gun. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the main structure of a heat shrink tubing heating device according to a specific embodiment 1 of this utility model;

[0019] Figure 2 This is a top view structural schematic diagram of a heat shrink tubing heating device according to a specific embodiment 1 of the present utility model;

[0020] Figure 3 This is a schematic diagram of the cross-sectional structure of a heat shrink tubing heating device according to a specific embodiment 1 of this utility model.

[0021] In the diagram: 1. Operating table; 2. Upper air vent; 3. Lower air vent; 4. Hot air duct; 5. Hot air chamber; 6. Thermocouple; 7. Air outlet; 8. Heating wire; 9. Return air duct; 10. Duct fan; 11. AC contactor; 12. Temperature controller; 13. Slot. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] Specific Implementation Example 1: Please refer to Figure 1-3 A heat shrink tubing heating device includes an operating table 1, on which a hot air chamber 5 is provided. The hot air chamber 5 has a hollow structure and a heating element, which is an electric heating wire 8, is provided inside the hot air chamber 5.

[0024] Heating wire 8 is connected to thermostat 12 via AC contactor 11. Heating wire 8 has high power and cannot be directly connected to thermostat 12. The hot air chamber 5 has a return air inlet and an air outlet 7 on the side wall near the heat shrink tubing to be processed. The air outlet 7 is located on the upper part of the side wall of the hot air chamber 5, and the return air inlet is located on the lower part of the side wall of the hot air chamber 5. The return air inlet is connected to a return air duct 9. An air guide is located at the end of the return air duct 9 furthest from the hot air chamber 5. The shape of the air guide is such that the outer cross-sectional area is large, gradually decreasing inwards. Air guides can also be designed at the furthest points of other air outlets (upper air outlet and / or lower air outlet). The hot air chamber 5 is equipped with a temperature sensor near the air outlet to monitor the temperature of the hot air chamber. The temperature sensor is a thermocouple 6. The temperature signal generated by the thermocouple 6 is transmitted to the temperature controller 12. The temperature controller 12 adjusts the opening and closing of the AC contactor 11 according to the temperature signal of the thermocouple 6, thereby controlling the operation of the heating wire 8. The air outlet is connected to the air blower through the hot air duct 4. The temperature inside the hot air chamber 5 is high, which is not good for the duct fan. The duct fan 10 is placed outside the hot air chamber 5 and set on the side wall of the hot air chamber 5. The front and rear sides of the duct fan 10 are connected to the return air outlet and the return air duct, respectively.

[0025] The operating table 1 provides convenient space for placing heat shrink tubing and retrieving the loading plate. A hot air chamber 5 is added, mixing temporary and newly heated gas for more stable temperature control, resulting in better performance than a hot air gun. The heating element is connected to a temperature sensor and a temperature controller. The controller sets a target temperature threshold to ensure the blown-out temperature meets the processing requirements of the heat shrink tubing. Based on the signal from the temperature sensor, the controller controls the heating element's operation. If the blown-out air temperature is lower than the target temperature threshold, the controller instructs the heating element to heat; if the blown-out air temperature is higher than the target temperature threshold, the controller instructs the heating element to stop heating. For example, the required heating temperature for heat shrink tubing is approximately 120 degrees Celsius, and the target temperature threshold can be within the range of 120 ± 10 degrees Celsius. Generally, heat shrink tubing only requires a few seconds to heat in a suitable hot air environment.

[0026] A duct fan 10 can achieve both blowing and returning air functions. Through the returning air device, the used hot air is recycled back into the hot air chamber 5 through the returning air duct 9. The hot air is blown directionally towards the heat shrink tubing through the air outlet, and the waste heat is recycled through the returning air outlet to save energy.

[0027] The power supply of the duct fan 10 is always on, maintaining a continuous airflow without the need for frequent start-stop. The duct fan draws outside air through the return air duct 9 to the heating element in the hot air chamber 5. At the same time, the duct fan 10 also directs the hot air in the hot air chamber 5 to the heat shrink tubing through the air outlet, hot air duct 4, and air blower.

[0028] There are two air outlets: an upper air outlet 2 and a lower air outlet 3. The upper air outlet 2 is located in the upper space of the worktable 1, and the lower air outlet 3 is located in the lower space of the worktable 1. The upper air outlet 2 and the lower air outlet 3 are positioned opposite each other. The worktable 1 has a slot 13 at the processing position to allow the heat shrink tubing to receive airflow from both the upper and lower outlets. The horizontal distance between the air outlet and the return air outlet is greater than 10cm. If the return air outlet is too close to the air outlet, hot air may be sucked back before it comes into contact with the heat shrink tubing.

[0029] The length of the groove 13 is greater than the length of the processing area, which is the area where the batch of heat shrink tubing is laid flat. The width of the groove 13 is greater than the width of the processing area to ensure that hot air blown from the top and bottom can also flow from the side of the heat shrink tubing.

[0030] The main power switch controls the power supply of the entire unit (the duct fan and heating element start simultaneously by default). The main power switch controls two circuits: one is the circuit containing the duct fan, and the other is the circuit containing the heating element, thermostat, and AC contactor.

[0031] An independent switch is connected in series on another circuit, except for the duct fan 10, which can be used to disconnect the circuit individually;

[0032] The duct fan 10 is directly connected to the main power switch, and the duct fan only stops when the main power switch is turned off. When using the equipment, turn on the main power switch, and both the duct fan 10 and the heating wire 8 will start working. After the temperature indicator on the temperature controller 12 reaches the set temperature, the heat shrink tubing processing will begin.

[0033] After work is completed, turn off the individual power switches for all devices except for the duct fan 10, allowing the duct fan 10 to continue running for a while until the temperature drops. Then, turn off all power. Rely on the duct fan 10 to continue running and cool down naturally. The user should manually turn off the main power switch after the temperature drops to the safe threshold.

[0034] During loading, the heat shrink tubing can be manually laid in the grooved area. After the worker controls the heating time to be sufficient, the heat shrink tubing is removed. Alternatively, a loading plate can be used to clamp the heat shrink tubing to be processed and move it to the air blower position for heating. The heating time is generally a few seconds. Those skilled in the art, who are already familiar with heating heat shrink tubing with a heat gun, can control the heating time when using this invention.

[0035] The volume of the hot air chamber 1 needs to be designed according to the heating requirements of the heat shrink tubing to ensure that the hot air is fully mixed and remains stable within the chamber. If the hot air chamber 1 is too large, it will cause the hot air flow to disperse, resulting in reduced thermal efficiency or energy waste; if the hot air chamber is too small, it may cause local overheating or poor airflow circulation, affecting the uniform heating of the heat shrink tubing.

[0036] The temperature threshold setting of the thermostat affects the stability of the hot airflow at the outlet. If the threshold is set too wide, it may cause excessive temperature fluctuations, affecting the shrinkage effect of the heat shrink tubing; if the threshold is set too narrow, it may cause the temperature control system to start and stop frequently, reducing the lifespan of the equipment.

[0037] Different materials and specifications of heat shrink tubing have different heating temperature requirements. For example, the shrinkage temperature of high-viscosity semi-rigid double-wall tubing used in automotive wiring harnesses is 125℃-200℃. It is recommended that the temperature controller be set to a threshold range of 130℃~170℃ for this heat shrink tubing at an ambient temperature of 25℃; while in low-temperature environments (10℃), the lower limit can be appropriately increased to 140℃ to compensate for heat loss.

[0038] For heat shrink tubing with a diameter of 5 mm or less and a length of 100 mm or less, the preferred volume of the hot air chamber is 3500 ± 500 cm³, at which point the hot air circulation efficiency is high and the heating uniformity is good.

[0039] A temperature sensor, linked to a temperature controller, dynamically adjusts the heating element to ensure stable hot air temperature that meets the requirements of heat shrink tubing. A continuously running duct fan maintains constant circulation, preventing fluctuations during start-stop cycles. The air outlet provides directional airflow, while the return air outlet recovers waste heat. The integrated duct fan (10 units) enables both blowing and returning air, facilitating waste heat recycling. A one-way baffle prevents backflow, resulting in a simple and reliable structure. The operating table (1 unit) features an optimized loading space. The hot air chamber (5 unit) temporarily stores the mixed gas, providing better temperature uniformity than a hot air gun.

[0040] Specific Embodiment 2: The difference between this specific embodiment and Specific Embodiment 1 is that the air outlet only has an upper air outlet and no lower air outlet. There are also no grooves on the work surface 1. The upper air outlet is used to process the heat shrink tubing placed on the work surface. In this specific embodiment, the heat shrink tubing placed on the work surface can be placed directly on the work surface or a feeding plate can be used.

[0041] Specific Embodiment 3: This specific embodiment differs from other specific embodiments in that it explicitly uses a specific structure for the feeding plate. The feeding plate consists of an upper plate and a lower plate, both of which are vertical mesh structures. The upper and lower plates can move relative to each other to form a clamping space for the heat shrink tubing when closed, and to allow the heat shrink tubing to be placed and removed when open. In this specific embodiment, one end of the upper and lower plates is hinged, allowing relative rotation, and the other end is a handle. The upper and lower plates have mutually cooperating handles facing the user for easy handling. When using the feeding plate, the upper plate is rotated using the handle, opening the feeding plate and laying the heat shrink tubing flat on the lower plate. Rotating the upper plate clamps the heat shrink tubing between the upper and lower plates. The user simultaneously grasps the handles of both the upper and lower plates, transferring the feeding plate onto the work surface and pushing it to the slotted position.

[0042] Specific embodiment 4: In this specific embodiment, the upper plate consists of two symmetrical and independent clamping arms, located on both sides of the lower plate. These arms can cooperate with the lower plate to limit the two ends of the heat shrink tubing. The upper plate and the lower plate are rotatably connected on one side, and each has a hand-held part that cooperates with the other side away from the rotating end.

[0043] Specific Embodiment 5: The difference between this specific embodiment and other specific embodiments is that a positioning block is provided on the operating table in this specific embodiment for positioning the heat shrink tubing or the feeding plate on the operating table. During feeding, the farthest position of the heat shrink tubing is limited, or if a feeding plate is used, a positioning block is provided at the farthest position of the feeding plate from the worker. The worker pushes the feeding plate towards the farthest end until the farthest end of the feeding plate touches the positioning block.

[0044] Specific Embodiment 6: This specific embodiment differs from any of the other technical solutions in Specific Embodiments 1-5 in that a one-way baffle is installed at the outer opening of the return air duct. This allows external gas (including residual hot air) to enter the hot air chamber, but prevents direct leakage of hot air from the hot air chamber. The one-way baffle can be a louver or a lightweight plastic sheet. Its lightweight design allows it to open easily with slightly stronger airflow, increasing the load on the duct fan almost entirely. The baffle automatically closes when the system stops, preventing backflow. The one-way baffle already meets the backflow prevention requirement and has a simpler and more reliable structure. It eliminates the need for complex structures such as solenoid valves and one-way valves. The system does not have high airtightness requirements, and backflow is unlikely during continuous operation of the duct fan.

[0045] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model; the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In addition, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances. Moreover, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0046] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A heat shrink tubing heating device, characterized in that: The device includes an operating table with a hot air chamber. The hot air chamber has a hollow structure and contains a heating element. The heating element is connected to a temperature controller via an AC contactor. A return air vent and an air outlet are located on the side wall of the hot air chamber near the heat shrink tubing to be processed. The air outlet is located on the upper part of the side wall of the hot air chamber, and the return air vent is located on the lower part of the side wall of the hot air chamber. A temperature sensor for monitoring the temperature of the hot air chamber is located near the air outlet. The signal generated by the temperature sensor is transmitted to the temperature controller. The air outlet is connected to a blower via a hot air duct. A duct fan is externally located within the hot air chamber and is positioned on the side wall of the hot air chamber. The front and rear sides of the duct fan are connected to the return air duct and the return air vent, respectively.

2. The heat shrink tubing heating device according to claim 1, characterized in that: The heating element is an electric heating wire.

3. The heat shrink tubing heating device according to claim 1, characterized in that: The temperature sensor is a thermocouple.

4. The heat shrink tubing heating device according to claim 1, characterized in that: A one-way baffle is installed at the outer opening of the return air duct.

5. The heat shrink tubing heating device according to claim 1, characterized in that: The power supply to the duct fan is normally on, and the duct fan blows air towards the heating element.

6. The heat shrink tubing heating device according to claim 5, characterized in that: The air outlet has two parts: an upper air outlet and a lower air outlet. The upper air outlet is located in the upper space of the work surface, and the lower air outlet is located in the lower space of the work surface. The work surface has a groove at the position to be processed, allowing the heat shrink tubing to be processed to receive air from the upper and lower air outlets.

7. A heat shrink tubing heating device according to claim 6, characterized in that: The length of the slot is greater than the length of the processing area, which is the area where the batch of heat shrink tubing is laid flat. The width of the slot is greater than the width of the processing area. The heat shrink tubing to be processed is clamped in the loading plate. The loading plate includes an upper plate and a lower plate. The length and width of the loading plate are both greater than the slot. The upper plate and the lower plate can move relative to each other so that they can jointly form a heat shrink tubing clamping space when in the closed position and allow the heat shrink tubing to be put in and taken out when in the open position. At least one side of the upper plate and the lower plate is provided with a mutually cooperating handle.

8. The heat shrink tubing heating device according to claim 7, characterized in that: The lower plate has a mesh structure to support the heat shrink tubing. An upper plate is provided above the lower plate to limit the heat shrink tubing. The upper plate and the lower plate are rotatably connected at the ends away from the handheld part. The upper plate has a gap to allow hot air from the upper air outlet to pass through.

9. A heat shrink tubing heating device according to claim 7, characterized in that: The lower plate has a mesh structure, and the upper plate consists of two symmetrical and independent clamping arms. The upper plate and the lower plate are rotatably connected on one side.

10. A heat shrink tubing heating device according to any one of claims 1-9, characterized in that: The operating table is provided with a positioning block at a corresponding position for positioning the feeding plate on the operating table. The equipment also includes a main power switch to control the power supply of the equipment.

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