A composite pot bottom hot press forming device

Abstract

The application discloses a kind of composite pot bottom hot press forming devices, belong to the technical field of intelligent production of cookware.The device includes rack, bottom mould, induction heating system, pressurizing system and control system.Induction heating system is provided with profile induction coil;Pressure system includes upper pressure head, pressure driving mechanism, pressure sensor, proportional pressure valve and elastic buffer structure;Control system includes controller and infrared temperature sensor.Controller is electrically connected with high-frequency / middle-frequency power supply, pressure driving mechanism, pressure sensor, proportional pressure valve and infrared temperature sensor, and constitutes temperature closed-loop control loop and pressure closed-loop control loop.The application realizes temperature-pressure collaborative control, eliminates impact damage, improves interlaminar bond strength and product consistency.

Description

Technical Field

[0001] This invention relates to the field of intelligent cookware manufacturing technology, specifically to a composite pot bottom hot pressing molding device. Background Technology

[0002] Composite cookware bottoms (such as stainless steel-aluminum alloy-copper multi-layer composite bottoms) are achieved through a hot-pressing process that bonds different metal layers at the molecular level, representing the mainstream structure for high-quality cookware. Existing hot-pressing equipment mainly suffers from the following technical problems:

[0003] (1) Poor heating uniformity: Fixed-shape induction coils or external heating cause large temperature differences in different parts of the pot bottom. The difference in thermal expansion coefficients between stainless steel and aluminum alloy can easily cause inconsistent grain growth at the interface, resulting in local delamination or warping.

[0004] (2) Large pressure impact and simple control: The pressure head driven by the cylinder or hydraulic cylinder generates an instantaneous impact, which can easily cause stress cracks in the high-temperature softened aluminum alloy layer; the pressure cannot be dynamically adjusted according to the real-time state of the material, which affects the quality of interlayer diffusion bonding.

[0005] (3) Lack of temperature-pressure coordinated closed-loop control: Existing equipment generally lacks real-time online closed-loop regulation of temperature and pressure. Temperature control and pressure control are independent of each other, and it is impossible to achieve the coordinated process of "heating to the target temperature first and then applying pressure, maintaining both temperature and pressure during the pressure holding period, and maintaining pressure to prevent deformation during the cooling stage", resulting in poor batch consistency.

[0006] Patent CN101559508B discloses a brazing machine for electrically heated composite pot bottoms, but it still has the above-mentioned defects, so a device is needed to solve the above problems. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems mentioned above, and provides a composite pot bottom hot pressing forming device, which solves the technical problems of impact damage, uneven heating and control separation of existing equipment through elastic buffer structure, temperature closed loop, pressure closed loop and their coordinated control.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A composite pot bottom hot pressing forming device, comprising: The frame has a lower base and an upper crossbeam; The bottom mold, set on the lower base, is used to position the workpiece; An induction heating system includes an induction heating coil and a high-frequency / medium-frequency power supply. The induction heating coil is arranged around the bottom mold and is electrically connected to the high-frequency / medium-frequency power supply. The pressurization system includes an upper pressure head, a pressure drive mechanism, a pressure sensor, a proportional pressure valve, and an elastic buffer structure. The pressure drive mechanism is mounted on the upper crossbeam. The upper pressure head is located directly above the bottom mold and is drively connected to the pressure drive mechanism. The pressure sensor is installed at the output end of the pressure drive mechanism. The proportional pressure valve is located on the pressure supply line of the pressure drive mechanism. The elastic buffer structure is connected in series between the output end of the pressure drive mechanism and the upper pressure head. The control system includes a controller and an infrared temperature sensor. The infrared temperature sensor is mounted on the frame and faces the heating area of ​​the bottom mold. The controller is electrically connected to the high-frequency / medium-frequency power supply, the pressure drive mechanism, the pressure sensor, the proportional pressure valve, and the infrared temperature sensor. The infrared temperature sensor, the high-frequency / medium-frequency power supply, and the controller form a temperature closed-loop control loop; the pressure sensor, the proportional pressure valve, and the controller form a pressure closed-loop control loop; the controller is configured to perform temperature-pressure coordinated control, that is, before pressure loading, the workpiece is heated to a preset temperature through the temperature closed-loop control loop, and then pressure loading is initiated.

[0009] Furthermore, the induction heating coil is a contour induction coil, the shape of which is adapted to the bottom plane and side wall curved surface of the workpiece, and is arranged around the periphery of the bottom mold and embedded inside the bottom mold.

[0010] Furthermore, the bottom mold is made of a high-temperature resistant, non-magnetic material.

[0011] Furthermore, the elastic buffer structure is a disc spring assembly.

[0012] Furthermore, the lower surface of the upper pressure head is provided with a conforming mold that matches the inner wall of the workpiece.

[0013] Furthermore, the pressure driving mechanism is a hydraulic cylinder.

[0014] Furthermore, the controller has a built-in process parameter recipe library for storing hot pressing process parameters corresponding to different pot bottom specifications.

[0015] Furthermore, the composite pot bottom hot pressing forming method of the composite pot bottom hot pressing forming device includes the following steps: S1. Loading and positioning: Positioning the workpiece on the bottom mold; S2. Induction heating and temperature closed-loop control: When the induction heating system is started, the controller adjusts the output power of the high-frequency / medium-frequency power supply according to the temperature signal fed back by the infrared temperature sensor, so that the composite area of ​​the workpiece is heated to the preset hot pressing temperature; S3. Pressure loading and pressure closed-loop control: When the temperature reaches the preset hot-pressing temperature, the pressure drive mechanism is activated. After the loading impact is absorbed by the elastic buffer structure, the upper pressure head applies pressure to the workpiece. The controller adjusts the pressure through the proportional pressure valve according to the pressure signal fed back by the pressure sensor, so that the actual pressure changes according to the preset pressure curve. S4. Heat and pressure holding: Maintain heating and pressurization for a predetermined time to allow atomic diffusion bonding between metal layers; S5. Cooling and Pressure Holding: Reduce heating power to cool the workpiece while maintaining pressure until the temperature drops to a safe demolding temperature; S6. Discharge: The upper pressure head rises and resets, removing the workpiece.

[0016] Furthermore, in step S2, the preset hot-pressing temperature is 350℃-550℃; the preset pressure curve includes a linear pressure increase stage, a heat preservation and pressure holding stage, and a cooling and pressure holding stage.

[0017] Furthermore, the controller is configured to simultaneously maintain temperature closed-loop control and pressure closed-loop control during the heat preservation and pressure holding stages and the cooling and pressure holding stages, thereby achieving coordinated regulation of temperature and pressure.

[0018] By adopting the above technical solution, the present invention has the following beneficial effects: 1. Eliminate pressure shocks and protect thin-walled workpieces. An elastic buffer structure (disc spring assembly or air bladder) is connected in series between the pressure drive mechanism and the upper pressure head to buffer and absorb the instantaneous impact energy when the pressure head contacts the workpiece. This avoids the rigid impact caused by direct drive of traditional pneumatic / hydraulic cylinders, and especially protects the aluminum alloy layer whose strength is significantly reduced at high temperatures. It effectively reduces stress cracks and deformation, and lowers the scrap rate.

[0019] 2. Achieve temperature-pressure coordinated closed-loop control to improve bonding quality. An infrared temperature sensor and controller form a temperature closed loop, while a pressure sensor and proportional pressure valve form a pressure closed loop. The controller is configured to first heat to the target temperature before initiating pressure loading, ensuring that the metal layer is pressurized during the optimal plasticity window to promote atomic diffusion. During the heat preservation, pressure holding, and cooling stages, temperature and pressure stability are maintained simultaneously to prevent warping caused by uneven thermal shrinkage. This synergistic control is not available in existing technologies that use independent open-loop control for temperature and pressure, significantly improving interlayer bonding strength and product consistency.

[0020] 3. Uniform heating, adaptable to complex curved surfaces The contour-following induction coil is designed according to the bottom plane and side wall curves of the pot. Combined with infrared temperature measurement and multi-point feedback, the temperature difference between different parts of the pot bottom is no more than ±10℃, which effectively suppresses the internal stress caused by thermal expansion differences and prevents local overheating or failure to fuse.

[0021] 4. Process parameters can be stored and recalled with one click, ensuring batch repeatability. The controller has a built-in process parameter formula library, which can pre-store the optimal temperature curve, pressure curve and holding time for pot bottoms of different materials, diameters and thicknesses. When changing production, it can be called up with one click, avoiding fluctuations in human experience and ensuring the consistency and traceability of mass production. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the composite pot bottom hot pressing forming device.

[0023] Figure 2 for Figure 1 A sectional view.

[0024] Figure 3 This is a block diagram of the control system in the composite pot bottom hot pressing forming device.

[0025] In the attached diagram, 100-frame, 110-lower base, 120-upper crossbeam, 130-column, 140-positioning worktable, 150-bottom mold, 200-induction heating system, 210-induction heating coil, 220-high frequency / medium frequency power supply, 300-pressurization system, 310-upper pressure head, 311-contouring mold, 320-pressure drive mechanism, 330-pressure sensor, 340-multi-stage pressure regulating valve group, 350-elastic buffer structure, 410-PLC controller, and 420-infrared temperature sensor. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or it may be centered within another component. When a component is described as "set to" another component, it can be directly set on the other component or it may be centered within another component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this article are for illustrative purposes only.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] like Figures 1 to 3 As shown, a preferred embodiment of the present invention provides a composite pot bottom hot pressing molding apparatus, including a frame 100, a bottom mold 150, an induction heating system 200, a pressurizing system 300 and a control system.

[0030] In this embodiment, the frame 100 includes a lower base 110 and an upper crossbeam 120. The lower base 110 and the upper crossbeam 120 are fixedly connected by four rectangularly arranged columns 130, forming a portal frame structure. The lower base 110, the upper crossbeam 120, and the columns 130 are made of cast or welded steel, and the overall rigidity meets the requirements for ≥1000-ton hot-compression loads.

[0031] A positioning worktable 140 is mounted on the lower base 110. The upper surface of the positioning worktable 140 is a precision-machined flat surface, and bolt holes for mounting the bottom mold 150 are provided on both sides. The bottom mold 150 is detachably mounted on the positioning worktable 140 by bolts, and the bottom mold 150 can be quickly replaced according to the specifications of different pot bottoms. The upper surface of the bottom mold 150 has a positioning cavity adapted to the shape of the workpiece, and the bottom plane and side wall curved surfaces of the positioning cavity are in close contact with the metal layers of the composite pot bottom.

[0032] In this embodiment, the induction heating system 200 includes an induction heating coil 210 and a high-frequency / medium-frequency power supply 220. The induction heating coil 210 is made of hollow copper tubing and is embedded inside the bottom mold 150. The induction heating coil 210 is arranged around the composite area of ​​the workpiece. The induction heating coil 210 is a contour-following induction coil, and its shape is adapted to the bottom plane and side wall curved surface of the composite pot bottom workpiece, so that the heating intensity of each part of the workpiece in the induction magnetic field is basically the same, avoiding local overheating or insufficient temperature rise.

[0033] The two ends of the induction heating coil 210 are electrically connected to the output terminals of the high-frequency / medium-frequency power supply 220 via coaxial cables. The operating frequency of the high-frequency / medium-frequency power supply 220 is adjustable, preferably ranging from 1kHz to 400kHz, to adapt to the heating needs of pot bottoms of different thicknesses and metal materials. The high-frequency / medium-frequency power supply 220 adopts a solid-state power module, which has the advantages of high efficiency, fast response, and good power regulation linearity.

[0034] The bottom mold 150 is made of high-temperature resistant non-magnetic material, preferably alumina ceramic or high-temperature resistant glass ceramic, so that the induced magnetic field can effectively penetrate the mold to reach the workpiece, while avoiding energy loss and mold damage caused by the mold itself heating up due to eddy current effect.

[0035] In this embodiment, the pressurization system 300 includes an upper pressure head 310, a pressure drive mechanism 320, a pressure sensor 330, a proportional pressure valve 341, and an elastic buffer structure 350. The pressure drive mechanism 320 is a hydraulic cylinder connected to a hydraulic station via hydraulic lines. The pressure drive mechanism 320 is fixedly installed on the top of the upper crossbeam 120 and extends towards the bottom mold 150. The upper pressure head 310 is located directly above the bottom mold 150 and is drively connected to the pressure drive mechanism 320. Specifically, the lower surface of the upper pressure head 310 is connected to the pressure drive mechanism 320, and the lower end of the upper pressure head 310 is directly opposite the center of the positioning cavity of the bottom mold 150. The lower surface of the upper pressure head 310 is provided with a contouring mold 311 adapted to the inner wall of the workpiece. The contouring mold 311 is made of heat-resistant alloy steel, and its surface curvature is consistent with the curvature of the bottom surface of the pot body to ensure that the pressure is applied evenly to the composite area of ​​the bottom of the pot.

[0036] The pressure sensor 330 is installed at the output end of the pressure drive mechanism 320. The pressure sensor 330 is used to detect the pressure value applied to the workpiece in real time and feed the pressure signal back to the control system.

[0037] The proportional pressure valve 341 is installed on the pipeline between the hydraulic station and the pressure drive mechanism 320, and works with the control system to achieve proportional pressure regulation. The pressure sensor 330, the proportional pressure valve 341, and the controller 410 together form a pressure closed-loop control circuit, enabling the actual pressure to change precisely according to a preset pressure curve.

[0038] An elastic buffer structure 350 is connected in series between the output end of the pressure drive mechanism 320 and the upper pressure head 310. In this embodiment, the elastic buffer structure 350 is a disc spring assembly. When the pressure drive mechanism 320 presses down rapidly, the elastic buffer structure 350 first compresses and absorbs the impact energy, allowing the upper pressure head 310 to smoothly contact the workpiece, effectively preventing stress cracks in the thin-walled pot body, especially in the aluminum alloy layer where the strength significantly decreases after heating to high temperatures. This buffer structure also makes the pressure value collected by the pressure sensor 330 more stable, eliminating the interference of impact oscillation on the accuracy of the pressure closed-loop control.

[0039] In this embodiment, the control system includes a PLC controller 410 and an infrared temperature sensor 420 connected to the PLC controller 410.

[0040] An infrared temperature sensor 420 is mounted on the frame 100, with its temperature probe facing the heating area of ​​the bottom mold 150, for non-contact real-time monitoring of the surface temperature of the composite area of ​​the workpiece. The infrared temperature sensor has a response time ≤1ms and a temperature measurement accuracy of ±5℃ or higher. The infrared temperature sensor 420, the high-frequency / medium-frequency power supply 220, and the controller 410 together form a temperature closed-loop control circuit. The controller automatically adjusts the heating power based on temperature feedback using a PID algorithm, ensuring that the workpiece temperature changes precisely according to a preset heating curve.

[0041] The PLC controller or industrial computer 410 is electrically connected to the high-frequency / medium-frequency power supply 220, the pressure drive mechanism 320, the pressure sensor 330, the proportional pressure valve 341, and the infrared temperature sensor 420, respectively. The controller 410 has a built-in process parameter recipe library, which can pre-store the hot-pressing temperature, heating rate, pressure curve, and holding time for different combinations of pot bottom materials, diameters, and thicknesses, and supports one-click recall.

[0042] More importantly, the controller 410 is configured to perform temperature-pressure coordinated control: during the pressure loading stage, the controller first relies on the temperature closed loop to heat the workpiece to the preset target temperature before activating the pressure closed loop for pressure loading; during the heat preservation and pressure holding stage, the controller 410 simultaneously maintains temperature and pressure stability; during the cooling and pressure holding stage, the controller 410 controls the reduction of heating power while maintaining pressure to prevent workpiece warping and deformation. This coordinated control ensures that atomic diffusion bonding is completed between metal layers in an optimal plastic state.

[0043] In this embodiment, the composite pot bottom hot pressing forming method of the composite pot bottom hot pressing forming device includes the following steps: S1. Loading and positioning: Select a matching bottom mold 150 according to the specifications of the pot bottom to be processed, and install it on the positioning worktable 140; place the composite pot bottom workpiece to be processed on the bottom mold 150, and quickly center and position it through the positioning cavity.

[0044] S2. Induction Heating and Temperature Closed-Loop Control: The induction heating system 200 is activated. Based on the temperature signal fed back by the infrared temperature sensor 420, the controller 410 automatically adjusts the output power of the high-frequency / medium-frequency power supply 220 using a PID algorithm, causing the composite area of ​​the workpiece to rise to the target hot-pressing temperature at a preset heating rate. Depending on the combination of different metal materials, the target hot-pressing temperature is preferably 350℃-550℃. This step ensures that the workpiece is uniformly heated to the material softening window without applying pressure.

[0045] S3. Pressure Loading and Closed-Loop Pressure Control: When the temperature reaches the preset target value, the controller 410 sends a command to activate the pressure drive mechanism 320. The upper pressure head 310 descends, and the elastic buffer structure 350 first compresses and absorbs the loading impact, allowing the upper pressure head to smoothly contact the workpiece. Subsequently, the upper pressure head 310 applies pressure to the workpiece, and the pressure sensor 330 provides real-time feedback on the pressure value. The controller 410 achieves closed-loop pressure regulation by controlling the proportional pressure valve 341, ensuring that the actual pressure changes according to a preset pressure curve, such as linear pressure increase or stepped pressure increase. Key point: Pressure loading only starts after the temperature reaches the target value, avoiding abnormal metal flow or poor bonding caused by applying pressure at low temperatures.

[0046] S4. Heat and pressure holding: Maintain the heat and pressure for the predetermined time, such as 60-120 seconds, depending on the thickness and area of ​​the workpiece. During this period, the controller maintains both temperature and pressure stability, allowing the interlayer atoms of the metal to obtain sufficient energy to migrate and diffuse into each other, forming a strong solid diffusion weld layer.

[0047] S5. Cooling and Pressure Holding: After the heat holding and pressure holding stage is completed, the controller 410 controls the induction heating system 200 to reduce the output power, so that the workpiece cools down at the preset cooling rate. At the same time, a certain pressure is maintained through pressure closed-loop control to prevent the workpiece from warping and deforming due to uneven thermal shrinkage. After the temperature drops to the safe demolding temperature, the upper pressure head 310 is controlled to rise and reset.

[0048] S6. Discharge: Remove the composited pot bottom to complete one work cycle.

[0049] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A composite pot bottom hot pressing forming device, characterized in that, include: The frame (100) has a lower base (110) and an upper crossbeam (120). A bottom mold (150) is disposed on the lower base (110) and is used to position the workpiece; An induction heating system (200) includes an induction heating coil (210) and a high-frequency / medium-frequency power supply (220), wherein the induction heating coil (210) is arranged around the bottom mold (150) and is electrically connected to the high-frequency / medium-frequency power supply (220); The pressurization system (300) includes an upper pressure head (310), a pressure drive mechanism (320), a pressure sensor (330), a proportional pressure valve (341), and an elastic buffer structure (350); the pressure drive mechanism (320) is mounted on the upper crossbeam (120); the upper pressure head (310) is located directly above the bottom mold (150) and is drively connected to the pressure drive mechanism (320); the pressure sensor (330) is installed at the output end of the pressure drive mechanism (320); the proportional pressure valve (341) is located on the pressure supply line of the pressure drive mechanism (320); the elastic buffer structure (350) is connected in series between the output end of the pressure drive mechanism (320) and the upper pressure head (310); The control system includes a controller (410) and an infrared temperature sensor (420). The infrared temperature sensor (420) is mounted on the frame (100) and faces the heating area of ​​the bottom mold (150). The controller (410) is electrically connected to the high-frequency / medium-frequency power supply (220), the pressure drive mechanism (320), the pressure sensor (330), the proportional pressure valve (341), and the infrared temperature sensor (420). The infrared temperature sensor (420), the high-frequency / medium-frequency power supply (220), and the controller (410) constitute a temperature closed-loop control loop; the pressure sensor (330), the proportional pressure valve (341), and the controller (410) constitute a pressure closed-loop control loop; the controller (410) is configured to perform temperature-pressure coordinated control, that is, before pressure loading, the workpiece is heated to a preset temperature through the temperature closed-loop control loop, and then pressure loading is started.

2. The composite pot bottom hot pressing forming device as described in claim 1, characterized in that, The induction heating coil (210) is a contour induction coil, the shape of which is adapted to the bottom plane and side wall curved surface of the workpiece, and is arranged around the periphery of the bottom mold (150) and embedded in the interior of the bottom mold (150).

3. The composite pot bottom hot pressing forming device as described in claim 1, characterized in that, The bottom mold (150) is made of a high-temperature resistant, non-magnetic material.

4. The composite pot bottom hot pressing forming device as described in claim 1, characterized in that: The elastic buffer structure (350) is a disc spring assembly.

5. The composite pot bottom hot pressing forming device as described in claim 1, characterized in that: The lower surface of the upper pressure head (310) is provided with a contouring die (311) that is adapted to the inner wall of the workpiece.

6. The composite pot bottom hot pressing forming device as described in claim 1, characterized in that: The pressure drive mechanism (320) is a hydraulic cylinder.

7. The composite pot bottom hot pressing forming device as described in claim 1, characterized in that: The controller (410) has a built-in process parameter formula library for storing hot pressing process parameters corresponding to different pot bottom specifications.

8. The composite pot bottom hot pressing forming device as described in claim 1, characterized in that, The composite pot bottom hot pressing forming method of the composite pot bottom hot pressing forming device includes the following steps: S1. Loading and positioning: Position the workpiece on the bottom mold (150); S2. Induction heating and temperature closed-loop control: Start the induction heating system (200), and the controller (410) adjusts the output power of the high-frequency / medium-frequency power supply (220) according to the temperature signal fed back by the infrared temperature sensor (420) so that the composite area of ​​the workpiece is heated to the preset hot pressing temperature; S3. Pressure loading and pressure closed-loop control: When the temperature reaches the preset hot-pressing temperature, the pressure drive mechanism (320) is activated. After the loading impact is absorbed by the elastic buffer structure (350), the upper pressure head (310) applies pressure to the workpiece. The controller (410) adjusts the pressure through the proportional pressure valve (341) according to the pressure signal fed back by the pressure sensor (330), so that the actual pressure changes according to the preset pressure curve. S4. Heat and pressure holding: Maintain heating and pressurization for a predetermined time to allow atomic diffusion bonding between metal layers; S5. Cooling and Pressure Holding: Reduce heating power to cool the workpiece while maintaining pressure until the temperature drops to a safe demolding temperature; S6. Discharge: The upper pressure head (310) rises and resets, and the workpiece is removed.

9. The composite pot bottom hot pressing forming device as described in claim 8, characterized in that, In step S2, the preset hot-pressing temperature is 350℃-550℃; the preset pressure curve includes a linear pressure increase stage, a heat preservation and pressure holding stage, and a cooling and pressure holding stage.

10. The composite pot bottom hot pressing forming device as described in claim 8, characterized in that, The controller (410) is configured to simultaneously maintain temperature closed-loop control and pressure closed-loop control during the heat preservation and pressure preservation stages and the cooling and pressure preservation stages, thereby achieving coordinated regulation of temperature and pressure.

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