Three-coating four-drying waste heat recovery leather embossing machine

Abstract

The invention discloses a three-coating four-drying waste heat recovery leather embossing machine, which relates to the technical field of leather production, and comprises an embossing mechanism, a thermal driving mechanism and a triggering mechanism, the thermal driving mechanism communicates with the dryer through a pipeline and is used for receiving drying waste heat, the thermal driving mechanism comprises a heat pipe arranged in the thermal driving mechanism, a flexible expansion sleeve is arranged on the outer side of the heat pipe in a sealed mode, the flexible expansion sleeve is filled with a thermosensitive driving medium, and the thermosensitive driving medium expands when heated and drives the flexible expansion sleeve to expand in the radial direction. The expanded flexible expansion sleeve is used for exerting a stretching effect on the leather; the embossing mechanism comprises a fixed roller and an embossing roller capable of moving vertically, and leather penetrates through a gap between the fixed roller and the embossing roller; and the triggering mechanism is used for connecting the flexible expansion sleeve and the embossing roller. The embossing machine is innovatively and deeply coupled with the upstream'three-coating and four-drying 'technological process, a large amount of industrial waste heat generated in the drying process is directly recycled through the thermal driving mechanism, and cyclic utilization of waste energy is achieved.

Description

Technical Field

[0001] This invention relates to the field of leather production technology, specifically to a three-coat, four-bake waste heat recovery leather embossing machine. Background Technology

[0002] In the production process of synthetic leather, the core finishing and drying processes typically employ a "three-coat, four-bake" method. This involves applying polyurethane (PU) slurry multiple times and combining it with multiple high-temperature drying processes to shape the leather layers. After completing the main "three-coat, four-bake" process, subsequent treatments such as embossing and area optimization are usually required. Existing leather embossing processes mainly rely on mechanically separated and independently operating systems to complete key steps. In the embossing stage, the equipment typically consists of a stationary roller and an embossing roller, and the gap between them is crucial to the embossing effect. Adjusting this gap often relies on manual operation or an independent actuator driven by a motor / hydraulic system. When the production line switches to process leather of different thicknesses or materials, operators need to stop production or interrupt the process to individually calibrate the vertical position of the embossing roller. Simultaneously, leather area optimization (i.e., length stretching) is usually achieved by applying mechanical stretching force after the "three-coat, four-bake" process is completed and before the embossing step. Therefore, the critical embossing gap adjustment, leather stretching and shaping, and the main "three-coat, four-bake" drying process are separate and unrelated in time and space.

[0003] This results in significant defects in the operating mode of existing devices, such as: 1. Inability to Achieve State Linkage and Synchronous Optimization: The biggest drawback lies in the disconnect between the embossing gap adjustment and the leather length stretching process. When the leather is in a thermoplastic state immediately after drying, its size and shape are most unstable. Traditional technology cannot simultaneously apply stretching force to the leather to resist shrinkage and optimize area when it is necessary to increase the gap between the fixed roller and the embossing roller (to adapt to temperature changes or thicker leather). This control disconnect not only affects the accuracy of embossing but also sacrifices the opportunity to maximize the finished product area by utilizing the thermoplasticity of the leather.

[0004] 2. Low adjustment efficiency and high energy consumption: Traditional gap adjustment relies on independent electric or hydraulic systems, resulting in slow adjustment speeds and requiring frequent manual intervention for fine-tuning. Furthermore, the large amount of waste heat generated during the multiple drying processes of leather is treated as exhaust gas and directly emitted, causing significant energy waste. Summary of the Invention

[0005] The purpose of this invention is to provide a leather embossing machine with three coatings and four baking cycles to recover waste heat, which solves the problems mentioned in the background art.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions: the present invention includes: an embossing mechanism, a heat-driven mechanism, and a triggering mechanism; The heat-driven mechanism is connected with the dryer through a pipeline for receiving the drying waste heat, and comprises a heat pipe arranged inside, a flexible expansion sleeve arranged outside the heat pipe, and a heat-sensitive driving medium filled in the flexible expansion sleeve. The embossing mechanism comprises a fixed roller and a vertically displaceable embossing roller, and the leather passes through a gap between the fixed roller and the embossing roller. The trigger mechanism is used for connecting the flexible expansion sleeve and the embossing roller, converting the radial expansion displacement of the flexible expansion sleeve into the vertical displacement of the embossing roller, and realizing the self-adaptive adjustment of the embossing gap.

[0007] Preferably, the heat-driven mechanism is provided with a driving member for driving the heat pipe and the flexible expansion sleeve to rotate.

[0008] Preferably, the driving member comprises a third motor fixed through a mounting seat, a gear fixed to the output end of the third motor, and an external gear ring fixed to the heat pipe and engaged with the gear.

[0009] Preferably, the heat pipe is provided with a heat-conducting member, which comprises a plurality of annularly distributed heat-conducting fins arranged on the inner side wall of the heat pipe and a heat-dissipating member connected with the heat-conducting fins, and the heat-dissipating member is located outside the heat pipe and inserted into the heat-sensitive driving medium.

[0010] Preferably, the heat-dissipating member comprises a first heat-conducting sheet and a second heat-conducting sheet arranged on the inner side of the first heat-conducting sheet, the thermal expansion coefficient of the second heat-conducting sheet is greater than that of the first heat-conducting sheet, and the heat-dissipating member realizes dynamic expansion to the outside through thermal deformation to continuously contact the heat-sensitive driving medium.

[0011] Preferably, the movable embossing roller of the embossing mechanism is slidingly installed through a moving seat, and the upper side of the moving seat is provided with a first spring, which provides a downward pre-tightening force or a reset force for the embossing roller.

[0012] Preferably, the trigger mechanism comprises a vertically flipped connecting rod, the connecting rod forms a lever, the long arm end of the connecting rod is connected with the flexible expansion sleeve, and the short arm end of the connecting rod is in abutment with the moving seat.

[0013] Preferably, the long arm end of the connecting rod is connected with the flexible expansion sleeve through a connecting member, the connecting member comprises a moving frame vertically slidingly arranged, a supporting wheel in abutment with the flexible expansion sleeve is rotatably installed on the upper side of the moving frame, and a second spring is arranged on the lower side of the moving frame, which gives the moving frame an upward reset force to drive the long arm end of the connecting rod to flip upward when the flexible expansion sleeve contracts.

[0014] Preferably, the heat-sensitive driving medium is a paraffin-based high-expansion composite material; and the flexible expansion sleeve is made of high-strength high-temperature-resistant elastomer or fiber-reinforced composite rubber material.

[0015] Preferably, side baffles are fixed on both sides of the heat pipe, and the side baffles abut against the end portions of the flexible expansion sleeve to limit the axial expansion of the flexible expansion sleeve.

[0016] Compared with the prior art, the present application has the following beneficial effects: The present application has the following beneficial effects, mainly in terms of energy utilization, process coupling, regulation accuracy and system stability: 1. The present application innovatively couples the embossing machine with the upstream "three-coating and four-drying" process, directly recycles a large amount of industrial waste heat (hot waste gas) generated during the drying process through a heat-driven mechanism, and realizes the recycling of waste energy. This mode of driving and stretching the gap with heat energy completely replaces the traditional mode of driving and adjusting by relying on independent electric or hydraulic systems, which fundamentally reduces the energy consumption and cost of equipment operation. The heat-driven mechanism does not require external power intervention, and is stable and easy to maintain. At the same time, the effective use of waste heat from the production line also significantly reduces the direct emission of waste gas, reflecting the environmental benefits of green manufacturing and sustainable development.

[0017] 2. The present application ingeniously solves the defect that the embossing gap adjustment and leather stretching process in the traditional process are disconnected in time and space. By using the expansion force of the heat-sensitive driving medium, the flexible expansion sleeve simultaneously applies radial extrusion and stretching action to the leather when the leather is just dried and is in the best thermoplastic state. This heat-driven linkage mode maximizes the use of the thermoplasticity of the leather to resist shrinkage and optimize the area of the finished product. In addition, since the gap adjustment and leather stretching are driven by the same heat source, the precise matching of the two with the temperature (thickness) state of the leather is ensured, effectively improving the embossing precision and the area utilization rate of the finished leather.

[0018] 3. The present application realizes intelligent and self-adaptive adjustment of the embossing gap, without the need for frequent manual calibration. The expansion size of the heat-driven mechanism is precisely coupled with the input waste heat temperature, converting temperature changes into driving displacement. The expansion force acts on the embossing roller through a high-lever-ratio connecting rod, realizing micron-level precise control of the gap between the fixed roller and the embossing roller. During the gap resetting process, the stored elastic force of the second spring is released, combined with the gravity of the first spring and the moving seat, forming a reliable reset driving chain, which ensures that the system can accurately and quickly adjust the gap to the desired optimal size in both the expansion state and the shrinkage state.

[0019] 4、The unique heat dissipation part in the application adopts a bimetallic strip structure as a dynamic thermal compensation mechanism between the heat pipe and the medium. The heat dissipation part can adaptively deform according to temperature changes, and expands outward (radially) with the expansion of the heat-sensitive driving medium, thereby dynamically compensating for the potential heat transfer gap generated during the expansion process. This design effectively eliminates the contact thermal resistance of the heat conduction interface, ensures that heat can be continuously and efficiently transferred to the driving medium, greatly improves the response sensitivity of the thermal drive mechanism to residual heat input, and thus guarantees the driving stability and reliability of the entire gap adjustment system. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram of the three-dimensional structure of the application; Figure 2 is a schematic diagram of the planar cross-sectional structure of Figure 1 ; Figure 3 is a schematic diagram of the half cross-sectional structure of the trigger mechanism and the thermal drive mechanism in Figure 1 ; Figure 4 is a schematic diagram of the three-dimensional structure of the thermal drive mechanism in Figure 1 ; Figure 5 is a schematic diagram of the half cross-sectional structure of the thermal drive mechanism in Figure 1 ; Figure 6 is a schematic diagram of the local three-dimensional structure of the heat pipe.

[0021] Numerical representation in the figure: 11 - setting roller; 12 - first motor; 13 - second motor; 14 - moving seat; 15 - embossing roller; 2 - thermal drive mechanism; 21 - heat pipe; 22 - flexible expansion sleeve; 23 - side baffle; 241 - gear; 242 - third motor; 243 - outer gear ring; 25 - heat-sensitive driving medium; 26 - heat-conducting fin; 27 - heat dissipation part; 271 - first heat-conducting sheet; 272 - second heat-conducting sheet; 3 - guide roller; 4 - trigger mechanism; 41 - connecting rod; 42 - contact block; 43 - first spring; 44 - support wheel; 45 - moving frame; 46 - second spring; 100 - leather. DETAILED DESCRIPTION

[0022] The above and other technical features and advantages of the present application will be described in more detail below with reference to the accompanying drawings.

[0023] The present embodiment provides a technical solution: a three-coating four-baking residual heat recovery leather embossing machine, as shown in Figures 1-6As shown, the device is located downstream of the "three-coating and four-drying" process in the embossing production line, and is used for length stretching and embossing operation of the leather 100 after high-temperature drying. It comprises a heat driving mechanism 2, an embossing mechanism located in the downstream process of the heat driving mechanism 2, and a trigger mechanism 4 connected between the heat driving mechanism 2 and the embossing mechanism. The device adjusts the gap between the fixed roller 11 and the embossing roller 15 in the embossing mechanism through the trigger mechanism 4.

[0024] A guide roller 3 is arranged upstream of the heat driving mechanism 2 to ensure that the leather 100 can be stably and accurately pulled to the position of the heat driving mechanism 2.

[0025] The embossing mechanism comprises a first mounting frame and a fixed roller 11 and an embossing roller 15 vertically distributed on the first mounting frame, and the embossing roller 15 is located on the upper side of the fixed roller 11. The fixed roller 11 is driven to rotate by a first motor 12 mounted on the first mounting frame, and the embossing roller 15 is vertically slidingly mounted on the first mounting frame to adjust the gap between the fixed roller 11 and the embossing roller 15. The specific mounting manner is that a moving seat 14 is vertically slidingly mounted on both sides of the first mounting frame, and both ends of the embossing roller 15 are respectively connected with the two moving seats 14, and the outer side of one of the moving seats 14 is fixed with a second motor 13 for driving the embossing roller 15 to rotate. When the first motor 12 and the second motor 13 drive the fixed roller 11 and the embossing roller 15 to rotate in opposite directions, the leather 100 can be pushed downstream, and under the action of the embossing roller 15, the embossing is left on the upper surface of the leather 100.

[0026] The heat driving mechanism 2 is used for absorbing and utilizing the drying waste heat to realize the synchronous stretching of the leather and the driving of the gap adjustment. It comprises a second mounting frame and a heat pipe 21 rotatably mounted on the second mounting frame. The air inlet end of the heat pipe 21 is connected with an air inlet pipe (not shown in the figure) through a first rotary joint (not shown in the figure), the air inlet pipe communicates with the inner cavity of the shell of a plurality of drying machines (not shown in the figure) in the embossing production line, and a gas pump (not shown in the figure) is mounted near the air inlet pipe. By the operation of the gas pump, the waste heat generated by the drying machine enters the heat pipe 21 through the air inlet pipe; the air outlet end of the heat pipe 21 is connected with an air outlet pipe (not shown in the figure) through a second rotary joint (not shown in the figure), the air outlet pipe is connected with an external waste gas treatment device (not shown in the figure) to purify the waste gas and finally reach the emission standard to be discharged. It should be noted that the outer surface of the air inlet pipe can be wrapped with a layer of heat insulation material to avoid the heat dissipation of the hot waste gas in the air inlet pipe.

[0027] A flexible expansion sleeve 22 is arranged outside the heat pipe 21, and includes two elastic ring spacers respectively arranged on both sides of the heat pipe 21, and an elastic ring cylinder is fixed between the two elastic ring spacers. A sealed annular storage chamber is formed between the heat pipe 21, the two elastic ring spacers and the elastic ring cylinder, and a heat-sensitive driving medium 25 is arranged in the annular storage chamber. The heat-sensitive driving medium 25 can expand / contract with the increase / decrease of temperature. In order to make the flexible expansion sleeve 22 only expand radially and not axially, side baffles 23 are fixed on both sides of the heat pipe 21, and the side baffles 23 abut against the end portions of the flexible expansion sleeve 22 to limit the axial expansion of the flexible expansion sleeve 22. When the hot exhaust gas enters the heat pipe 21, the heat thereof is transferred to the heat-sensitive driving medium 25 through the heat pipe 21, so that the heat-sensitive driving medium 25 expands, and the flexible expansion sleeve 22 also expands to press and stretch the leather 100.

[0028] The heat-sensitive driving medium 25 used in the present application should have a high volume expansion coefficient and good thermal stability at a temperature range of 60-150°C, which is usually the temperature range of the residual heat of the dryer. A paraffin-based high-expansion composite material or a solid heat-sensitive polymer is preferred. Paraffin-based material is a commonly used medium for heat driving, which has a significant volume change near the melting point, and the expansion is stable and reversible. By encapsulating it in a composite system of high-thermal-conductivity powder, the thermal conductivity efficiency and expansion uniformity can be improved.

[0029] The flexible expansion sleeve 22 is used to encapsulate the heat-sensitive driving medium 25 and bear the great pressure generated by the expansion of the heat-sensitive driving medium 25, and needs to be in direct contact with the leather 100 for stretching, so it must meet the requirements of heat resistance, high strength, high flexibility, wear resistance and air tightness. A high-strength high-temperature-resistant elastomer or a fiber-reinforced composite rubber material, such as high-temperature-resistant fluororubber or aramid fiber-reinforced silicone rubber / acrylonitrile rubber, is preferred.

[0030] In an optional embodiment, in order to further increase the reaction efficiency of the heat-sensitive driving medium 25, a heat-conducting member is arranged on the heat pipe 21, and the heat-conducting member includes a plurality of heat-conducting fins 26 fixed on the heat pipe 21, and the plurality of heat-conducting fins 26 are annularly distributed. The heat-conducting fins 26 are made of copper material and have good thermal conductivity, so that the heat in the hot exhaust gas can be quickly absorbed and transferred to the heat-sensitive driving medium 25.

[0031] A heat-dissipating member 27 is arranged outside the heat-conducting fins 26. The heat-dissipating member 27 is a core structure for realizing heat conduction self-adaptive compensation, and is composed of a first heat-conducting sheet 271 and a second heat-conducting sheet 272 which are closely adhered and combined, and has the structure characteristics of a bimetallic sheet. Thus, when heated, it can stretch straight out or bend in the opposite direction to the outside to continuously and closely contact the expanding medium.

[0032] The first heat-conducting sheet 271 and the second heat-conducting sheet 272 of the heat-dissipating member 27 are made of heat-conducting metal materials with different thermal expansion coefficients. The thermal expansion coefficient of the second heat-conducting sheet 272 (located at the inner layer) is greater than that of the first heat-conducting sheet 271 (located at the outer layer). The second heat-conducting sheet 272 is made of brass material, for example. The first heat-conducting sheet 271 is made of invar material, for example. When the hot exhaust gas passes through the heat pipe 21, due to the difference in thermal expansion coefficients between the first heat-conducting sheet 271 and the second heat-conducting sheet 272, the overall heat-dissipating member 27 will undergo predictable bending deformation, causing its bending degree to gradually decrease and expand outward (radially).

[0033] This outward expansion displacement is synchronous and consistent with the radial expansion displacement of the heat-sensitive driving medium 25 after being heated. The heat-dissipating member 27 dynamically compensates for the potential gap between the outer surface of the expansion medium and the heat-conducting surface through its own deformation, ensuring that they always maintain close and effective contact. This greatly improves the continuity and efficiency of heat transfer, ensuring the response sensitivity and stability of the thermal drive mechanism 2 to heat.

[0034] Further, the second mounting frame is provided with a driving member for driving the heat pipe 21 to rotate, the driving member comprising a third motor 242 fixed to the second mounting frame through a mounting seat, a gear 241 fixed to the output end of the third motor 242, and an external gear ring 243 fixed to the heat pipe 21 and engaged with the gear 241, so that when the third motor 242 is operated, the heat pipe 21 and the flexible expansion sleeve 22 are driven to rotate through the cooperation of the gear 241 and the external gear ring 243. After the flexible expansion sleeve 22 is expanded, the flexible expansion sleeve 22 contacts the leather 100, and the rotating flexible expansion sleeve 22 can reduce the friction between the flexible expansion sleeve 22 and the leather 100.

[0035] The trigger mechanism 4 is used to push the height of the embossing roller 15 upward when the flexible expansion sleeve 22 is expanded, so as to adjust the gap between the fixed roller 11 and the embossing roller 15. The specific structure of the trigger mechanism 4 comprises a connecting rod 41 rotatably connected to the first mounting frame through a rotating shaft, the connecting rod 41 forming a lever, one end of the connecting rod 41 being a short arm end, and the other end of the connecting rod 41 being a long arm end connected to the thermal drive mechanism 2. A contact block 42 is fixed to the lower side of the moving seat 14, and a first spring 43 is arranged between the upper side of the moving seat 14 and the first mounting frame. The force of the first spring 43 pushes the moving seat 14 downward, and the weight of the embossing roller 15 is sufficient to effectively emboss the leather 100. The first spring 43 can also be omitted. A connecting member is arranged on the lower side of the flexible expansion sleeve 22 and fixed to the second mounting frame, and the long arm end of the connecting rod 41 is connected to the connecting member of the trigger mechanism 4.

[0036] Further, the adapter includes a moving frame 45 slidingly arranged on the second mounting frame, a supporting wheel 44 is rotatably arranged on the upper side of the moving frame 45, and the supporting wheel 44 is located on the same vertical line as the axis of the flexible expansion sleeve 22, a horizontal plate fixed to the second mounting frame is arranged on the lower side of the moving frame 45, a rectangular rod is fixed to the lower side of the moving frame 45 and slidingly penetrates the horizontal plate, a second spring 46 is arranged between the horizontal plate and the moving frame 45, the second spring 46 gives the moving frame 45 an upward displacement force, and the long arm end of the connecting rod 41 is in contact with the lower end of the moving frame 45.

[0037] Rotating wheels are rotatably arranged on both ends of the connecting rod 41, and the two rotating wheels are in contact with the bottom of the moving frame 45 and the contact block 42, respectively, so as to reduce the friction between the connecting rod 41 and the contact block 42 and the moving frame 45.

[0038] When the flexible expansion sleeve 22 is radially expanded, the moving frame 45 will be pushed downward, and the second spring 46 will be compressed, and the long arm end of the connecting rod 41 will be flipped downward, and due to the principle of leverage, the short arm end of the connecting rod 41 will be flipped upward, so as to slightly push the moving seat 14 and the embossing roller 15 upward, adjust the size between the fixed roller 11 and the embossing roller 15, and adapt to different thicknesses of the leather 100; conversely, when the flexible expansion sleeve 22 is radially contracted, the second spring 46 releases the stored elastic force, drives the moving frame 45 to displace upward, so that the long arm end of the connecting rod 41 will be flipped upward by a certain angle, and the moving seat 14 and the embossing roller 15 will displace downward due to the gravity and the action force of the first spring 43, so as to adjust the gap between the fixed roller 11 and the embossing roller 15 and ensure the accurate resetting of the gap.

[0039] It should be noted that the flexible expansion sleeve 22 abuts against and pushes the long arm end of the connecting rod 41, and the short arm end of the connecting rod 41 abuts against the moving seat 14, so that under the principle of leverage, the force generated by the expansion of the flexible expansion sleeve 22 can effectively pry the embossing roller 15 to displace upward.

[0040] When the thicker leather 100 is dried, a higher temperature is required, and the greater the thickness of the leather 100, the greater the stretching range of the heat-driven mechanism 2, and in addition, the greater the gap between the fixed roller 11 and the embossing roller 15, the higher the temperature, and the greater the radial expansion size of the flexible expansion sleeve 22, that is, the greater the stretching range of the heat-driven mechanism 2, so as to complete the perfect coupling of the device.

[0041] The embodiment perfectly integrates the drying waste heat, the thermal expansion drive, and the mechanical lever of the connecting rod 41, realizes the synchronous linkage of the gap adjustment and the leather stretching and the self-adaptive adjustment to different thicknesses of the leather, and effectively solves the defects of process disconnection and energy waste in the prior art.

[0042] The above descriptions are only the preferable embodiments of the present application, which are only illustrative but not restrictive. It is understood by those skilled in the art that many changes, modifications, even equivalences can be made to the present application within the spirit and scope defined by the claims of the present application, and all of them will fall into the protection scope of the present application.

Claims

1. A leather embossing machine with three coatings and four baking cycles for waste heat recovery, characterized in that, include: Embossing mechanism, heat drive mechanism (2) and triggering mechanism (4); The heat drive mechanism (2) is connected to the dryer through a pipe and is used to receive the waste heat from drying. The heat drive mechanism (2) includes a heat pipe (21) inside, and a flexible expansion sleeve (22) is sealed on the outside of the heat pipe (21). The flexible expansion sleeve (22) is filled with a heat-sensitive driving medium (25). The heat-sensitive driving medium (25) expands when heated and drives the flexible expansion sleeve (22) to expand radially. The expanded flexible expansion sleeve (22) is used to apply a stretching effect to the leather. The embossing mechanism includes a fixed roller (11) and an embossing roller (15) that can be vertically displaced, with the leather (100) passing through the gap between the fixed roller (11) and the embossing roller (15); The triggering mechanism (4) is used to connect the flexible expansion sleeve (22) and the embossing roller (15), and to convert the radial expansion displacement of the flexible expansion sleeve (22) into the vertical displacement of the embossing roller (15) to achieve adaptive adjustment of the embossing gap.

2. The three-coat, four-bake waste heat recovery leather embossing machine as described in claim 1, characterized in that, The heat drive mechanism (2) is provided with a drive component for driving the heat pipe (21) and the flexible expansion sleeve (22) to rotate.

3. The three-coat, four-bake waste heat recovery leather embossing machine as described in claim 2, characterized in that, The drive unit includes a third motor (242) fixed by a mounting base, a gear (241) fixed at the output end of the third motor (242), and an external gear ring (243) fixed on the heat pipe (21) and meshing with the gear (241).

4. The three-coat, four-bake waste heat recovery leather embossing machine as described in claim 1, characterized in that, The heat pipe (21) is provided with a heat-conducting component, which includes a plurality of annularly distributed heat-conducting fins (26) disposed on the inner sidewall of the heat pipe (21) and a heat dissipation component (27) connected to the heat-conducting fins (26). The heat dissipation component (27) is located outside the heat pipe (21) and inserted into the heat-sensitive driving medium (25).

5. The three-coat, four-bake waste heat recovery leather embossing machine as described in claim 4, characterized in that, The heat sink (27) includes a first heat-conducting sheet (271) and a second heat-conducting sheet (272) attached to the inner side of the first heat-conducting sheet (271). The coefficient of thermal expansion of the second heat-conducting sheet (272) is greater than that of the first heat-conducting sheet (271). The heat sink (27) achieves dynamic expansion to the outside through thermal deformation to continuously and closely contact the heat-sensitive driving medium (25).

6. The three-coat, four-bake waste heat recovery leather embossing machine according to claim 1, characterized in that, The movable embossing roller (15) of the embossing mechanism is slidably mounted on a movable seat (14). A first spring (43) is provided on the upper side of the movable seat (14), which provides a downward preload or reset force for the embossing roller (15).

7. The three-coat, four-baking waste heat recovery leather embossing machine as described in claim 6, characterized in that, The triggering mechanism (4) includes a vertically flipping link (41), which forms a lever. The long arm of the link (41) is connected to the flexible expansion sleeve (22), and the short arm of the link (41) abuts against the moving seat (14).

8. The three-coat, four-bake waste heat recovery leather embossing machine as described in claim 7, characterized in that, The long arm end of the connecting rod (41) is connected to the flexible expansion sleeve (22) by a connector. The connector includes a vertically sliding movable frame (45). A support wheel (44) that abuts against the flexible expansion sleeve (22) is rotatably mounted on the upper side of the movable frame (45). A second spring (46) is provided on the lower side of the movable frame (45). The second spring (46) gives the movable frame (45) an upward reset force to drive the long arm end of the connecting rod (41) to flip upward when the flexible expansion sleeve (22) contracts.

9. The three-coat, four-bake waste heat recovery leather embossing machine as described in claim 1, characterized in that, The thermally sensitive driving medium (25) is a paraffin-based high-expansion composite material; the flexible expansion sleeve (22) is made of a high-strength, high-temperature resistant elastomer or fiber-reinforced composite rubber material.

10. The three-coat, four-bake waste heat recovery leather embossing machine as described in claim 1, characterized in that, Both sides of the heat pipe (21) are fixed with side baffles (23), which abut against the end of the flexible expansion sleeve (22) to restrict the axial expansion of the flexible expansion sleeve (22).

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