An in-mold resistance thermal shearing control system, control method, and injection mold.

Abstract

This invention discloses an in-mold resistive thermal cutting control system, control method, and injection mold, relating to the field of injection molding technology. In the control system, a drive unit drives an electrothermal cutter unit to reciprocate along the cutting direction within the injection mold. The cutter unit's blade end is provided with a resistive heating layer, an insulating layer, and a high-temperature resistant contact surface. A temperature sensor is embedded in the resistive heating layer and feeds back a temperature signal to a temperature controller. The temperature controller adjusts the power supply state of the power module to the resistive heating layer. The timing control unit receives the injection molding machine's pressure holding completion signal and synchronously outputs drive control signals and heating control signals. Through the technical solution of this invention, the cutter movement can be matched with the resistive heating process, allowing heat to be concentrated on the cutting position of plastic residue or runner solidified material. This reduces problems such as burrs, tears, blade sticking, and cutting instability caused by cold cutting, improving the smoothness of the in-mold thermal cutting cut, the consistency of the action, and the continuous production efficiency.

Description

Technical Field

[0001] This invention relates to the field of injection molding technology, and in particular to an in-mold resistance thermal cutting control system, an in-mold resistance thermal cutting control method, and an injection mold. Background Technology

[0002] In the production of automotive injection molded parts, after the product is molded, it is usually necessary to separate the residual plastic material or runner solidified material from the product body. To reduce subsequent secondary processing steps, some injection molds adopt in-mold cutting, that is, after the injection molding machine completes processes such as injection and pressure holding, a cutting blade is driven by a hydraulic cylinder or other drive mechanism to move inside the mold, so that the cutting blade cuts off the residual plastic material or runner solidified material.

[0003] Existing in-mold cutting solutions mostly employ a cold-cutting blade combined with hydraulic cylinder drive and timing control. This type of solution typically involves the injection molding machine outputting a trigger signal after the holding pressure is completed, which is then controlled by a controller to move the hydraulic cylinder, driving the cutter to eject and cut off the plastic residue or solidified material in the runner using mechanical shearing force. While this method enables automatic in-mold cutting, the cutting process relies primarily on mechanical shearing force. For low-melting-point, high-viscosity, or highly tough plastic materials, burrs, tears, or stretching deformation are prone to occur at the cut, affecting the appearance quality and assembly accuracy of the injection molded parts.

[0004] Furthermore, plastic residue or runner solidification can easily adhere to the blade during cold cutting, causing poor blade retraction or material residue at the cutting position, requiring machine shutdown for cleaning and affecting continuous production efficiency. Even with a heated blade solution, if the heating area of ​​the blade head, the insulation structure, the temperature feedback location, and the timing of the blade's movement are not coordinated, problems such as unstable cutting temperature, excessive heat transfer to the blade body or mold, and insufficient temperature when the blade reaches its position can easily occur, leading to fluctuations in cut quality.

[0005] Therefore, it is necessary to provide a control system suitable for cutting plastic residue or runner solidified material in injection molds, so that the cutter forms a stable hot cutting temperature during the cutting time after the holding pressure is completed, and coordinates with the cutting time sequence, thereby reducing the problems of burrs, tearing, sticking and unstable cutting caused by cold cutting. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides an in-mold resistive thermal cutting control system, control method, and injection mold. By incorporating a resistive heating layer, an insulating layer, and a high-temperature resistant contact surface within the electrothermal cutting unit, a concentrated heat source is formed at the cutting position within the mold. The insulating layer restricts heat conduction to the blade body, thereby reducing the impact of heat on the blade body and mold while allowing the high-temperature resistant contact surface to thermally cut plastic residue or runner solidification, reducing burrs, tears, and stretching deformation caused by cold cutting. By embedding a temperature sensor in the resistive heating layer and adjusting the power supply state of the power module based on the temperature signal by a temperature controller, the cutting heat is kept stable, reducing temperature fluctuations when cutting different plastic materials. A timing control unit receives the pressure holding completion signal from the injection molding machine and synchronously outputs drive control signals and heating control signals, matching the movement of the electrothermal cutting unit with the heating process. This reduces situations where the temperature is insufficient or cutting is delayed when the blade reaches its position, improving the stability of in-mold thermal cutting and continuous production efficiency.

[0007] To achieve the above objectives, the present invention provides an in-mold resistance thermal cutting control system, including a drive unit, an electrothermal cutting knife unit, a temperature control unit, and a timing control unit; The drive unit is used to drive the electrothermal cutter unit to reciprocate along the cutting direction inside the injection mold; The electrothermal cutting unit includes a blade body and a resistance heating layer, an insulating heat insulation layer, and a high-temperature resistant contact surface disposed at the end of the blade body. The resistance heating layer is used to generate cutting heat after being energized. The insulating heat insulation layer is used to limit the heat generated by the resistance heating layer from being conducted to the blade body. The high-temperature resistant contact surface is used to contact plastic residue or runner solidified material and perform hot cutting. The temperature control unit includes a temperature controller, a power module, and a temperature sensor. The temperature controller is connected to the power module and the temperature sensor respectively. The power module is connected to the resistive heating layer. The temperature sensor is embedded in the resistive heating layer and feeds back a temperature signal to the temperature controller. The temperature controller adjusts the power supply state of the power module to the resistive heating layer according to the temperature signal. The timing control unit is used to receive the pressure holding completion signal of the injection molding machine, and synchronously outputs a drive control signal and a heating control signal in response to the pressure holding completion signal. The drive control signal is used to control the drive unit to drive the electrothermal cutter unit to move towards the plastic residue or runner solidified material, and the heating control signal is used to trigger the temperature control unit to supply power to the resistive heating layer.

[0008] In the above technical solution, preferably, the drive unit includes a hydraulic cylinder, and the electrothermal cutting unit is rigidly connected to the piston rod of the hydraulic cylinder through a flange structure.

[0009] In the above technical solution, preferably, the power module is connected to the resistive heating layer through a high-temperature resistant wire, and an insulating sleeve is provided on the outside of the high-temperature resistant wire.

[0010] In the above technical solution, preferably, the insulating and heat-insulating layer is located between the resistive heating layer and the blade.

[0011] In the above technical solution, preferably, the operating temperature of the resistive heating layer is 200°C to 300°C.

[0012] In the above technical solution, preferably, the timing control unit includes a timing controller, which is connected to the injection molding machine to receive a pressure holding completion signal, the first output terminal of the timing controller is connected to the control terminal of the drive unit, and the second output terminal of the timing controller is connected to the temperature controller.

[0013] In the above technical solution, preferably, the timing control unit is further configured to output an initial position confirmation signal before the injection molding machine injects the glue, and to output a reset control signal and a power-off control signal after hot cutting is completed. The initial position confirmation signal is used to control the drive unit to keep the electrothermal cutting blade unit in the initial position, the reset control signal is used to control the drive unit to drive the electrothermal cutting blade unit to retract from the cutting position to the initial position, and the power-off control signal is used to control the temperature control unit to stop supplying power to the resistive heating layer.

[0014] In the above technical solution, preferably, the driving unit includes a servo motor and a lead screw transmission mechanism, and the servo motor drives the electrothermal cutting unit to reciprocate along the cutting direction through the lead screw transmission mechanism.

[0015] This invention also proposes an in-mold resistance thermal shearing control method, applicable to the in-mold resistance thermal shearing control system disclosed in any of the above technical solutions, comprising: Before the injection molding machine injects the material, the control drive unit keeps the electrothermal cutter unit in its initial position; Receive the pressure holding completion signal from the injection molding machine; In response to the pressure holding completion signal, a drive control signal and a heating control signal are output synchronously. The drive unit is controlled by the drive control signal to move the electrothermal cutting unit toward the plastic residue or the solidified material in the flow channel, and the temperature control unit is triggered by the heating control signal to supply power to the resistance heating layer. Temperature signals are collected by a temperature sensor embedded in the resistive heating layer, and the power supply state of the power module to the resistive heating layer is adjusted according to the temperature signals. Hot cutting of plastic residue or runner solidified material is performed by contacting the surface with high temperature resistance. After hot cutting is completed, the drive unit is controlled to move the electrothermal cutting blade unit back from the cutting position to the initial position and stop supplying power to the resistive heating layer.

[0016] The present invention also proposes an injection mold, including a mold body and an in-mold resistance thermal cutting control system disclosed in any of the above technical solutions. The in-mold resistance thermal cutting control system is installed on the mold body, and the high-temperature resistant contact surface of the electrothermal cutting blade unit is set towards the cutting position of the plastic residue or runner solidified material in the mold body. The in-mold resistance thermal cutting control system is positioned and cooperated with the mold body through a positioning pin.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By setting a resistance heating layer, an insulating heat insulation layer and a high-temperature resistant contact surface in the electrothermal cutting unit, the heat generated by the resistance heating layer is concentrated on the cutting area at the end of the blade, and the high-temperature resistant contact surface contacts the plastic residue or runner solidified material to complete the hot cutting. Compared with the cold cutting method that relies on mechanical shearing force, this structure can reduce the pulling, tearing and burrs of plastic materials during the cutting process and improve the smoothness of the cut.

[0018] (2) By limiting the heat generated by the resistive heating layer to the blade body through the insulation and heat insulation layer, the heat can be reduced to reduce the impact of heat on the blade body, drive connection parts and local areas of the mold, so that the heat is mainly concentrated at the contact position that needs to be cut, which is conducive to maintaining the structural stability of the electrothermal cutting unit and the temperature concentration at the cutting position.

[0019] (3) By embedding a temperature sensor into the resistive heating layer and adjusting the power supply from the power module to the resistive heating layer according to the temperature signal by the temperature controller, a temperature feedback control for the resistive heating layer is formed. This method can reduce temperature fluctuations during the cutting process, enabling different plastic materials to obtain more stable cutting heat during hot cutting, and reducing the risk of sticking to the blade and incomplete cutting.

[0020] (4) The timing control unit receives the pressure holding completion signal from the injection molding machine and synchronously outputs drive control signal and heating control signal in response to the pressure holding completion signal, so that the movement process of the electrothermal cutter unit matches the heating process of the resistance heating layer. This can reduce the fluctuation in cutting quality caused by insufficient temperature, delayed heating or deviation in the timing of action when the cutter reaches the cutting position, and improve the stability and continuous production efficiency of the in-mold hot cutting process. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an in-mold resistance thermal cutting control system disclosed in one embodiment of the present invention.

[0022] In the diagram, the correspondence between the components and the reference numerals is as follows: 1. Drive unit; 2. High-temperature resistant wire; 3. Electrothermal cutting unit; 4. Resistance heating layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0024] The present invention will now be described in further detail with reference to the accompanying drawings: like Figure 1 As shown, an in-mold resistance thermal cutting control system according to the present invention includes a drive unit 1, an electrothermal cutting knife unit 3, a temperature control unit and a timing control unit. The units cooperate with each other to achieve automated thermal cutting of plastic residue or runner solidified material in the injection mold.

[0025] The drive unit 1 serves as the power source, driving the electrothermal cutter unit 3 to reciprocate along the cutting direction within the injection mold. This allows the electrothermal cutter unit 3 to enter or exit the cutting position where plastic residue and runner solidified material are located during the injection molding cycle. The drive unit 1 provides a stable reciprocating driving force, ensuring high precision and consistency of the electrothermal cutter unit 3 during the cutting process. This guarantees the repeatability of the cutting position and depth, preventing cutting position deviation due to unstable driving force.

[0026] The electrothermal cutting unit 3 includes a blade body, with a resistance heating layer 4, an insulating and heat-insulating layer, and a high-temperature resistant contact surface at the end of the blade body. The resistance heating layer 4 generates cutting heat at the end of the blade body after being energized, changing the cutting method from mechanical shearing to high-temperature thermal cutting, thereby reducing burrs and tearing caused by mechanical shearing force. The insulating and heat-insulating layer restricts the heat generated by the resistance heating layer 4 from being conducted to the blade body, concentrating the heat near the cutting end close to the plastic residue or runner solidified material, preventing heat from being conducted along the blade body to the drive mechanism, and preventing the drive components from failing or being damaged due to temperature rise. The high-temperature resistant contact surface is used to directly contact the plastic residue or runner solidified material to be cut and perform thermal cutting, withstanding the high temperature and contact force during cutting, ensuring a smooth cutting surface, effectively solving the problem of low-melting-point, high-viscosity plastic materials sticking to the blade, and also avoiding the tensile deformation of high-toughness plastic materials during cold cutting.

[0027] The temperature control unit includes a temperature controller, a power module, and a temperature sensor, which together form a closed-loop constant temperature control circuit. The temperature controller is connected to both the power module and the temperature sensor. The power module is connected to the resistive heating layer 4, and the temperature sensor is embedded in the resistive heating layer 4. It collects the operating temperature of the resistive heating layer 4 in real time and feeds back the temperature signal to the temperature controller. This allows for the acquisition of temperature signals closer to the heating area. Based on the temperature signal, the temperature controller dynamically adjusts the power supply from the power module to the resistive heating layer 4, ensuring stable cutting heat. Through closed-loop control, the temperature can be stably maintained within the preset cutting temperature range, taking into account the melting characteristics of different plastic materials. This reduces the risk of carbonization due to excessively high temperatures or incomplete cutting due to insufficient temperatures.

[0028] The timing control unit receives the pressure holding completion signal from the injection molding machine and synchronously outputs drive control signals and heating control signals in response to the pressure holding completion signal. The drive control signal controls the drive unit 1 to move the electrothermal cutter unit 3 towards the plastic residue or runner solidified material. The heating control signal triggers the temperature control unit to supply power to the resistance heating layer 4, so that the movement of the electrothermal cutter unit 3 is coordinated with the heating process of the resistance heating layer 4. After the injection molding machine completes the pressure holding, the plastic material is basically formed in the mold cavity. At this time, the drive unit 1 and the temperature control unit are synchronously triggered, so that the electrothermal cutter unit 3 moves towards the residue position while heating up to the cutting working temperature. This achieves a high degree of synchronization between the drive action and the heating rise in timing, ensuring that the cutter reaches the cutting position exactly within the optimal cutting temperature range, thereby completing high-quality hot cutting without delaying the production cycle.

[0029] In this embodiment, through the above-described structure and control relationship, hot cutting can replace simple mechanical cold cutting, reducing the occurrence of burrs, tears, stretching deformation and sticking to the blade during cutting of plastic residue or runner solidified material, and improving the stability of the in-mold cutting process, thereby enhancing product appearance quality and production efficiency.

[0030] In the above embodiment, preferably, the drive unit 1 includes a hydraulic cylinder, and the electrothermal cutting unit 3 is rigidly connected to the piston rod of the hydraulic cylinder through a flange structure. The hydraulic cylinder, as a power source, provides a stable reciprocating driving force along the cutting direction to the electrothermal cutting unit 3, so that the linear reciprocating motion output by the hydraulic cylinder can be stably transmitted to the electrothermal cutting unit 3. The hydraulic cylinder uses hydraulic pressure as the driving medium and has the advantages of large output force, smooth movement, and fast control response. It can maintain stable driving performance in the high temperature and high pressure working environment inside the injection mold, ensuring that the cutting position has high precision and high consistency.

[0031] The flange connection firmly fixes the electrothermal cutter unit 3 and the hydraulic cylinder piston rod into one unit, eliminating relative displacement and wobbling between them and ensuring the linear motion accuracy of the electrothermal cutter unit 3 in the cutting direction. The flange structure can increase the connection contact area and improve the connection rigidity between the cutter body and the piston rod, reducing the sway of the electrothermal cutter unit 3 during the upward cutting and retraction reset processes. The rigid connection method also ensures that the driving force output by the hydraulic cylinder can be completely transmitted to the electrothermal cutter unit 3, avoiding energy loss and motion lag caused by flexible connections, enabling the cutter to overcome melting resistance when contacting plastic residue and smoothly complete the cutting stroke.

[0032] In this embodiment, while retaining the structural stability and reliability advantages of the existing hydraulic cylinder in-mold cutting device, it is suitable for in-mold cutting scenarios that require large pushing force and relatively stable repetitive actions. It can improve the consistency of the electric heating cutter unit 3 reaching the cutting position, reduce the cutting position deviation caused by cutter offset, and improve the motion accuracy of the electric heating cutter unit 3, thereby ensuring the consistency of the cutting position and the stability of the hot cutting quality each time.

[0033] In the above embodiment, the resistance heating layer 4 generates a high temperature of 200°C to 300°C during operation, and applies heat to the plastic residue through the high-temperature resistant contact surface. The ambient temperature around the electrothermal cutting unit 3 is significantly higher than normal. Ordinary wires will experience insulation softening, melting, or even short circuits within this temperature range, affecting power supply reliability and posing safety hazards. Preferably, the power module is connected to the resistance heating layer 4 via a high-temperature resistant wire 2, ensuring reliable long-term energy conduction by the wire in the high-temperature operating environment of the electrothermal cutting unit 3, and ensuring stable power supply control of the resistance heating layer 4 by the temperature control unit. The high-temperature resistant wire 2 is used to transfer the electrical energy output from the power module to the resistance heating layer 4, allowing the resistance heating layer 4 to convert the electrical energy into cutting heat. An insulating sleeve is provided on the outside of the high-temperature resistant wire 2. The insulating sleeve provides electrical insulation protection for the wire and reduces the impact of the high-temperature environment inside the mold or localized heat from the cutting head on the power supply line, protecting other components inside the mold from high temperatures.

[0034] In this embodiment, the combination of the high-temperature resistant wire 2 and the insulating sleeve enables the electrical connection part to have both high-temperature resistance and insulation safety, which can improve the reliability of the power supply path of the resistive heating layer 4, reduce the risk of heat damage or insulation failure of the line, and thus ensure the stable heating of the electrothermal cutting unit 3 in continuous production cycle.

[0035] In the above embodiment, preferably, the insulating and heat-insulating layer is located between the resistive heating layer 4 and the blade. After the resistive heating layer 4 generates heat, the side closer to the high-temperature resistant contact surface is used to form a cutting heat source, while the side closer to the blade is thermally isolated by the insulating and heat-insulating layer. This arrangement is key to achieving precise heat orientation: the high-temperature heat generated by the resistive heating layer 4 after being energized acts on the plastic residue through the high-temperature resistant contact surface to achieve melting and cutting. At the same time, the insulating and heat-insulating layer physically cuts off the conduction path of the heat generated by the resistive heating layer 4 to the blade side, so that the heat is concentrated in the cutting area at the end where the resistive heating layer 4 and the high-temperature resistant contact surface are located. Through this interlayer arrangement, the heat of the resistive heating layer 4 is not easily transferred in large quantities to the blade and its rear connecting structure, so that the heat is concentrated on the cutting area of ​​the plastic residue or the solidified material in the flow channel.

[0036] If there is no insulating heat insulation layer to block it, or if the insulating heat insulation layer is not properly positioned, the heat generated by the resistance heating layer 4 will be conducted along the blade towards the drive unit 1, causing the temperature of the cylinder piston rod, flange connection and related seals to rise, causing the seals to age and deform, and the viscosity of the hydraulic oil to decrease, thereby affecting the hydraulic stability and service life of the cylinder.

[0037] In this embodiment, the insulating and heat-insulating layer is sandwiched between the resistive heating layer 4 and the blade body, which can minimize the heat conduction on the blade body side, reduce the heat impact on the blade body, drive connection part and local area of ​​mold, and improve the heat utilization efficiency of the blade tip.

[0038] In the above embodiment, preferably, the operating temperature of the resistance heating layer 4 is 200°C to 300°C. This temperature range takes into account the thermophysical parameters of commonly used plastic materials in injection molding and the actual requirements of in-mold cutting processes. Within this temperature range, the resistance heating layer 4 can generate enough heat to soften or melt the material when the high-temperature resistant contact surface comes into contact with plastic residue or runner solidified material.

[0039] The softening or melting point of common thermoplastic materials used in injection molding (such as PP, ABS, PA, PC, etc.) is usually between 120℃ and 280℃. For plastic materials with low melting point, high viscosity, or high toughness, this temperature range is beneficial for reducing the tensile stress caused by simple mechanical shearing. Applying heat significantly higher than the material's softening or melting point causes the plastic material in the contact area to melt rapidly, thereby separating the residual material from the product by hot melt cutting, resulting in a smooth and clean cut, effectively avoiding burrs, tears, and tensile deformation caused by mechanical shearing forces during cold cutting.

[0040] Meanwhile, the upper limit of 200℃ to 300℃ is also for safety and process stability considerations: excessive temperature will cause excessive thermal decomposition or carbonization of the plastic material around the cutting part, affecting the appearance and performance of the product; while through the closed-loop constant temperature control of the temperature control unit, the working temperature of the resistance heating layer 4 can be accurately maintained within this range, which has good cutting adaptability to different types and specifications of plastic materials.

[0041] In this embodiment, setting the temperature range can improve the smoothness of the hot cut and reduce the adhesion of residual material to the blade and incomplete cutting.

[0042] In the above embodiments, preferably, the timing control unit includes a timing controller, which is the core processing component of the entire timing control unit. The timing controller is responsible for receiving the process status signals from the injection molding machine and outputting control signals according to preset logic. The timing controller is connected to the injection molding machine and is used to receive the pressure holding completion signal output by the injection molding machine after the pressure holding process is completed. This signal serves as a trigger source, ensuring that the entire hot cutting action starts immediately after the pressure holding process of injection molding is completed, guaranteeing precise synchronization between the cutting timing and the injection molding process.

[0043] The first output terminal of the timing controller is connected to the control terminal of the drive unit 1 and is used to send an action control signal to the drive unit 1 to control the drive unit 1 to drive the electric heating cutter unit 3 to move towards the cutting position of the plastic residue or the runner solidified material; the second output terminal of the timing controller is connected to the temperature controller and is used to send a heating trigger signal to the temperature control unit to trigger the temperature controller to start the power supply and heating control of the resistive heating layer 4.

[0044] The timing controller synchronously outputs drive control signals and heating control signals through two independent output terminals, ensuring that the mechanical movement of drive unit 1 and the heating process of electrothermal cutting unit 3 are highly synchronized in time. On the one hand, the synchronous start of heating and movement reduces the waiting time for heating, shortens the single cutting cycle, and improves the production cycle time; on the other hand, the independent output of the two signals ensures that the two functional channels do not interfere with each other and operate stably according to the preset logic, thereby achieving precise timing control of the hot cutting process.

[0045] In this embodiment, the above signal allocation relationship enables the cutting blade's upward movement and the cutting blade's heating movement to coordinate around the injection molding machine's pressure holding completion node, reducing the fluctuation in cutting quality caused by the misalignment of the cutting and heating movements.

[0046] In the above embodiment, preferably, the timing control unit is also used to output an initial position confirmation signal before injection molding. The initial position confirmation signal is used to control the drive unit 1 to keep the electrothermal cutter unit 3 in the initial position, so that the electrothermal cutter unit 3 avoids the mold closing and plastic filling process, prevents the cutter head from interfering with the cavity filling, and leaves sufficient space for mold closing and injection. During the injection stage of the injection molding machine, the molten plastic fills the mold cavity under high pressure. If the electrothermal cutter unit 3 does not retract to the initial position, it will occupy the mold cavity space, hinder the flow and filling of plastic, and cause product molding defects or even damage to the mold.

[0047] After hot cutting is completed, the timing control unit outputs a reset control signal and a power-off control signal. The reset control signal controls the drive unit 1 to move the electrothermal cutting blade unit 3 back from the cutting position to the initial position, preparing for the next injection-hot cutting cycle. The power-off control signal controls the temperature control unit to stop supplying power to the resistance heating layer 4. Timely power-off after hot cutting avoids energy waste caused by prolonged continuous heating of the resistance heating layer 4, and reduces the impact of heat accumulation in the mold on the mold structure and seals, thus extending the service life of the device.

[0048] In this embodiment, through the orderly output of the initial position confirmation signal, drive control signal, heating control signal, reset control signal, and power-off control signal in a complete cycle during the control process, the electrothermal cutter unit 3 can complete avoidance, cutting, and reset within one injection molding cycle. The resistance heating layer 4 can also stop heating after cutting, thereby reducing the thermal impact of the non-cutting stage and preparing for the next injection molding cycle. The actions of each stage are incorporated into a unified timing management system to achieve precise linkage with the entire process of the injection molding machine.

[0049] In the above embodiment, preferably, the drive unit 1 includes a servo motor and a lead screw transmission mechanism. The servo motor outputs rotational motion, which is converted into linear reciprocating motion of the electrothermal cutting unit 3 along the cutting direction by the lead screw transmission mechanism. By controlling the rotation direction and amount of the servo motor, the upward cutting and retraction reset of the electrothermal cutting unit 3 can be achieved.

[0050] Specifically, the servo motor has precise position, speed, and torque control capabilities. The lead screw transmission mechanism converts the rotary motion of the servo motor into the linear reciprocating motion of the electrothermal cutting unit 3, resulting in high transmission efficiency, small backlash, and high positioning repeatability. By controlling the speed and angle of the servo motor, the feed speed, cutting stroke, and cutting pressure of the electrothermal cutting unit 3 can be precisely set, achieving more flexible motion control than hydraulic cylinder drive.

[0051] Compared to hydraulic cylinder-driven solutions, servo motor-driven solutions eliminate the need for hydraulic stations and complex hydraulic piping, resulting in a simpler system structure, lower maintenance costs, and the elimination of the impact of hydraulic oil leakage on mold cleanliness. Furthermore, servo drive solutions offer greater flexibility in cutting speed adjustment. The cutting feed speed can be adjusted via controller parameters based on the melting characteristics of different plastic materials and the shape and size of the runner material, further enhancing the controllability of cutting quality.

[0052] In this embodiment, the servo motor drive scheme is used in combination with the electrothermal cutting knife unit 3, the temperature control unit, and the timing control unit. This enables the reciprocating motion of the cutting head without changing the basic coordination relationship between the units, and is suitable for mold structures that require the use of motor drive to arrange the drive mechanism.

[0053] This invention also proposes an in-mold resistance thermal shearing control method, applied to the in-mold resistance thermal shearing control system disclosed in any of the above embodiments, comprising: Before the injection molding machine injects the material, the control drive unit 1 keeps the electrothermal cutter unit 3 in its initial position so that the electrothermal cutter unit 3 does not interfere with the injection and pressure holding process, thereby protecting the mold and the electrothermal cutter unit 3 itself from damage.

[0054] After the injection molding machine completes the holding pressure, the system receives a holding pressure completion signal. Holding pressure completion means that the plastic material in the mold cavity has been fully filled and compacted under pressure, the product outline has been basically formed, and the residual material or runner solidified material is ready to be separated and cut from the finished product. The holding pressure completion signal serves as a trigger source to achieve precise linkage between the timing control unit and the injection molding machine process.

[0055] In response to the pressure holding completion signal, the drive control signal and the heating control signal are output synchronously. After receiving the pressure holding completion signal, the timing control unit immediately sends control commands to the drive unit 1 and the temperature control unit to realize the timing synchronization of mechanical movement and heating. When the electric heating cutter unit 3 reaches the cutting position, it is ensured that it has been heated to the effective cutting temperature, shortening the waiting time and not affecting the overall production cycle.

[0056] According to the drive control signal, the drive unit 1 drives the electrothermal cutting unit 3 to move towards the plastic residue or runner solidified material, and according to the heating control signal, the temperature control unit is triggered to supply power to the resistance heating layer 4; the drive unit 1 responds to the drive control signal and drives the electrothermal cutting unit 3 to move towards the target position along the cutting direction; at the same time, the temperature control unit responds to the heating control signal and supplies electrical energy to the resistance heating layer 4 through the power module, so that it begins to heat up.

[0057] Temperature signals are collected by a temperature sensor embedded in the resistive heating layer 4, and the power supply state of the power module to the resistive heating layer 4 is adjusted according to the temperature signals. The temperature sensor measures the temperature of the resistive heating layer 4 in real time, and the temperature controller dynamically adjusts the output power of the power module according to the feedback temperature signals to form a closed-loop constant temperature control, so as to stably maintain the working temperature of the resistive heating layer 4 in the optimal cutting range of 200℃ to 300℃, which can meet the hot cutting requirements of different plastic materials.

[0058] The high-temperature resistant contact surface is used to thermally cut plastic residue or runner solidified material; the electrothermal cutter unit 3 moves to the cutting position, the high-temperature resistant contact surface contacts the plastic residue or runner solidified material, and the residue is separated from the product by high-temperature melting.

[0059] After hot cutting is completed, the control drive unit 1 drives the electrothermal cutting blade unit 3 to retract from the cutting position to the initial position and stops supplying power to the resistance heating layer 4. After hot cutting is completed, the drive unit 1 responds to the reset control signal and brings the electrothermal cutting blade unit 3 back to the initial safe position; at the same time, the temperature control unit responds to the power-off control signal and stops supplying power to the resistance heating layer 4 to avoid energy waste caused by continuous heating and thermal damage to the mold structure, thus completing a complete injection-hot cutting cycle, and the system enters a ready state waiting for the next injection trigger.

[0060] In this embodiment, by executing the above steps in an orderly manner, the safe avoidance, synchronous heating drive, closed-loop constant temperature hot cutting, and post-cutting reset power-off of the electrothermal cutting unit 3 are integrated into one, realizing precise linkage with the entire injection molding process, which improves the cutting quality while ensuring production efficiency and system safety.

[0061] The present invention also proposes an injection mold, including a mold body and an in-mold resistance thermal cutting control system disclosed in any of the above embodiments. The in-mold resistance thermal cutting control system is installed on the mold body, and the mold body provides an installation foundation for the electrothermal cutting knife unit 3, the drive unit 1 and related control circuits, thereby realizing a high degree of integration between the thermal cutting device and the main structure of the mold, and avoiding the process damage and efficiency loss caused by the need for secondary processing outside the mold in the traditional solution.

[0062] The high-temperature resistant contact surface of the electrothermal cutting unit 3 is positioned facing the cutting position of the plastic residue or runner solidified material inside the mold body. This orientation design ensures that the electrothermal cutting unit 3, driven by the drive unit 1, reaches the target cutting position at the correct angle and along the correct path, guaranteeing accurate and consistent application of heat to the plastic residue or runner solidified material with each heat cut, resulting in stable and repeatable cutting performance. During injection molding, after the plastic material is filled and pressurized within the mold body, the in-mold resistance heat cutting control system can directly heat-cut the plastic residue or runner solidified material within the mold, reducing subsequent secondary cutting processes.

[0063] The in-mold resistance thermal cutting control system uses locating pins to position the electrothermal cutting unit 3 in conjunction with the mold body, maintaining a stable relative position between the electrothermal cutting unit 3 and the cutting position. This ensures that the electrothermal cutting unit 3 is precisely aligned with the cutting target during installation, eliminating the risk of cutting position deviation due to installation errors. During multiple mold closing and opening cycles and production cycles, the positioning pins also ensure the stability of the system's installation position on the mold body, preventing displacement due to vibration or thermal expansion and contraction. This guarantees the consistency of the cutting position and the stability of the cutting quality throughout long-term production.

[0064] In this embodiment, the installation and positioning method enables automated synchronous cutting of the runner slurry within the mold, which improves the consistency of the cutting position in each molding cycle, reduces cut offset caused by system assembly deviation, and helps improve the appearance quality of injection molded parts and production continuity.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An in-mold resistance thermal cutting control system, characterized in that, It includes a drive unit, an electrothermal cutting unit, a temperature control unit, and a timing control unit; The drive unit is used to drive the electrothermal cutter unit to reciprocate along the cutting direction inside the injection mold; The electrothermal cutting unit includes a blade body and a resistance heating layer, an insulating heat insulation layer, and a high-temperature resistant contact surface disposed at the end of the blade body. The resistance heating layer is used to generate cutting heat after being energized. The insulating heat insulation layer is used to limit the heat generated by the resistance heating layer from being conducted to the blade body. The high-temperature resistant contact surface is used to contact plastic residue or runner solidified material and perform hot cutting. The temperature control unit includes a temperature controller, a power module, and a temperature sensor. The temperature controller is connected to the power module and the temperature sensor respectively. The power module is connected to the resistive heating layer. The temperature sensor is embedded in the resistive heating layer and feeds back a temperature signal to the temperature controller. The temperature controller adjusts the power supply state of the power module to the resistive heating layer according to the temperature signal. The timing control unit is used to receive the pressure holding completion signal of the injection molding machine, and synchronously outputs a drive control signal and a heating control signal in response to the pressure holding completion signal. The drive control signal is used to control the drive unit to drive the electrothermal cutter unit to move towards the plastic residue or runner solidified material, and the heating control signal is used to trigger the temperature control unit to supply power to the resistive heating layer.

2. The in-mold resistance thermal cutting control system according to claim 1, characterized in that, The drive unit includes a hydraulic cylinder, and the electrothermal cutter unit is rigidly connected to the piston rod of the hydraulic cylinder via a flange structure.

3. The in-mold resistance thermal cutting control system according to claim 1, characterized in that, The power module is connected to the resistive heating layer via a high-temperature resistant wire, and an insulating sleeve is provided on the outside of the high-temperature resistant wire.

4. The in-mold resistance thermal cutting control system according to claim 1, characterized in that, The insulating and heat-insulating layer is located between the resistive heating layer and the blade.

5. The in-mold resistance thermal cutting control system according to claim 1, characterized in that, The operating temperature of the resistive heating layer is 200℃ to 300℃.

6. The in-mold resistance thermal cutting control system according to claim 1, characterized in that, The timing control unit includes a timing controller, which is connected to the injection molding machine to receive a pressure holding completion signal. The first output terminal of the timing controller is connected to the control terminal of the drive unit, and the second output terminal of the timing controller is connected to the temperature controller.

7. The in-mold resistance thermal cutting control system according to claim 1, characterized in that, The timing control unit is also used to output an initial position confirmation signal before the injection molding machine injects the glue, and to output a reset control signal and a power-off control signal after hot cutting is completed. The initial position confirmation signal is used to control the drive unit to keep the electrothermal cutting unit in the initial position. The reset control signal is used to control the drive unit to drive the electrothermal cutting unit to retract from the cutting position to the initial position. The power-off control signal is used to control the temperature control unit to stop supplying power to the resistive heating layer.

8. The in-mold resistance thermal cutting control system according to claim 1, characterized in that, The drive unit includes a servo motor and a lead screw transmission mechanism. The servo motor drives the electrothermal cutting unit to reciprocate along the cutting direction through the lead screw transmission mechanism.

9. A method for controlling the thermal shearing of in-mold resistance, characterized in that, The in-mold resistance thermal shearing control system applied to any one of claims 1 to 8 comprises: Before the injection molding machine injects the material, the control drive unit keeps the electrothermal cutter unit in its initial position; Receive the pressure holding completion signal from the injection molding machine; In response to the pressure holding completion signal, a drive control signal and a heating control signal are output synchronously. The drive unit is controlled by the drive control signal to move the electrothermal cutting unit toward the plastic residue or the solidified material in the flow channel, and the temperature control unit is triggered by the heating control signal to supply power to the resistance heating layer. Temperature signals are collected by a temperature sensor embedded in the resistive heating layer, and the power supply state of the power module to the resistive heating layer is adjusted according to the temperature signals. Hot cutting of plastic residue or runner solidified material is performed by contacting the surface with high temperature resistance. After hot cutting is completed, the drive unit is controlled to move the electrothermal cutting blade unit back from the cutting position to the initial position and stop supplying power to the resistive heating layer.

10. An injection mold, characterized in that, The invention includes a mold body and an in-mold resistance thermal cutting control system as described in any one of claims 1 to 8. The in-mold resistance thermal cutting control system is installed on the mold body, and the high-temperature resistant contact surface of the electrothermal cutting blade unit is positioned facing the cutting position of the plastic residue or runner solidified material inside the mold body. The in-mold resistance thermal cutting control system is positioned and engaged with the mold body by a positioning pin.

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