Vacuum inflation heat sealing device for food packaging

Abstract

The invention discloses a vacuum inflation heat-sealing device for food packaging, which belongs to the field of food packaging and comprises a machine body, a bearing platform is fixedly connected to the upper end of the front surface of the machine body, and a heat-sealing assembly for heat-sealing food packaging bags is arranged at the upper end of the machine body and above the bearing platform; the heat sealing assembly comprises a control motor fixedly connected to the inner wall of the machine body, the output end of the control motor is fixedly connected with a connecting rod, one end of the connecting rod is rotationally connected with a swing rod, and the upper end of the swing rod is rotationally connected with a driving rod. Through the arrangement of the heat sealing assembly, the pressing force on the bag opening of the food packaging bag can be adjusted in real time according to the thickness of the food packaging bag, so that it is guaranteed that the food packaging bags with different thicknesses can obtain proper pressing force, and the situation that the bag opening is crushed to cause deformation of a sealing area or air leakage is caused by untight sealing is avoided; the rejection rate of the vacuum inflation heat sealing device is reduced, the packaging cost is further reduced, and the yield and the packaging efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the field of food packaging, and more specifically, to a vacuum inflation heat-sealing device for food packaging. Background Art

[0002] In the food industry, vacuum packaging is very common. All kinds of cooked products such as chicken legs, hams, sausages, grilled fish slices, beef jerky, etc., pickled products such as various pickled vegetables, soy products, preserved fruits, etc. all need to be vacuum-packed. Foods packed in vacuum have a long shelf life, which greatly extends the shelf life of foods. The vacuum inflation heat-sealing device, also known as a vacuum inflation packaging machine, is a common device for vacuum-packing foods.

[0003] During the vacuum inflation packaging process, for the heat-sealing step, the heat-sealing strip and the pressing plate need to cooperate with each other. The pressing plate provides an appropriate pressure to tightly press the bag mouth of the packaging bag on the heat-sealing strip. However, in the prior art, the thickness difference of the bag mouth (0.05 - 0.3 mm) will cause uneven pressure applied by the traditional rigid pressing plate. For example, there is a huge difference in thickness between the ultra-thin aluminum-plastic composite film and the thick co-extruded film. In this case;

[0004] For an overly thin bag mouth (such as 0.05 mm): Excessive pressure (>20 N) may break the bag mouth or cause deformation of the sealing area;

[0005] For an overly thick bag mouth (such as 0.3 mm): Insufficient pressure (<5 N) may cause the seal to be not tight, resulting in air leakage.

[0006] The prior art usually relies on manual adjustment or a fixed pressure mode and cannot dynamically adapt to different thicknesses, resulting in an increase in the rejection rate, thereby increasing the packaging cost, and at the same time reducing the yield rate and packaging efficiency. Summary of the Invention

[0007] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a vacuum inflation heat-sealing device for food packaging.

[0008] To solve the above problems, the present invention adopts the following technical solutions.

[0009] A vacuum inflation heat-sealing device for food packaging, including a machine body. A base is fixedly connected to the upper end position of the front surface of the machine body. Above the base and at the upper end of the machine body, there is a heat-sealing component for heat-sealing food packaging bags;

[0010] The heat-sealing assembly includes a control motor fixedly connected to the inner wall of the machine body. The output end of the control motor is fixedly connected to a connecting rod. One end of the connecting rod is rotatably connected to a swing rod. The upper end of the swing rod is rotatably connected to a driving rod. One end of the driving rod is rotatably connected to a fixed seat fixedly connected to the inner wall of the machine body, and the other end of the driving rod is fixedly connected with an upper mold assembly for providing pressure to the mouth of the food packaging bag. A high-precision laser displacement sensor is arranged at the upper end of the upper mold assembly. A lower mold body is fixedly connected to the upper surface of the platform corresponding to the position of the upper mold assembly, and a heat-sealing strip is embedded at the upper end of the lower mold body.

[0011] Furthermore, an air nozzle is movably arranged at the upper end inside the machine body and extends to the outside. The air nozzle is arranged corresponding to the middle position of the heat-sealing assembly. A cylinder is fixedly connected inside the machine body, and the output end of the cylinder is fixedly connected to the air nozzle. A control panel is arranged at the top of the front surface of the machine body. An inert gas input port is also arranged on the outer surface of one side of the machine body. A vacuum pump is arranged at the bottom of the machine body. One end of the air nozzle is respectively connected to the inert gas input port and the vacuum pump through pipelines, and the terminals of the two pipelines are jointly connected to the air nozzle through a three-way valve.

[0012] Furthermore, the upper mold assembly includes a substrate fixedly connected to the other end of the driving rod. A cavity is formed at the bottom of the substrate. Edge welding parts are arranged around the upper end of the cavity and are welded to connect a corrugated Ni-Ti alloy laminate through the edge welding parts. A heat-conducting plate is embedded in the top wall of the cavity, and evenly distributed thin-film pressure sensors are embedded at the bottom of the heat-conducting plate. A high-temperature resistant silica gel layer is adhesively connected to the bottom of the corrugated Ni-Ti alloy laminate;

[0013] A ventilation cavity is formed at the upper end of the substrate. Heat dissipation fins are evenly arranged on the bottom wall of the ventilation cavity. An air outlet and a pressure balance port are respectively formed at both ends of the ventilation cavity. An axial flow fan is fixedly connected at a position on one side of the ventilation cavity close to the pressure balance port. The height of the axial flow fan inside the ventilation cavity is higher than the height of the heat dissipation fins;

[0014] It also includes a processing unit for controlling the upper mold assembly to output an appropriate pressure.

[0015] Furthermore, the corrugated Ni-Ti alloy laminate includes five mutually welded corrugated Ni-Ti alloy single sheets. A high-temperature resistant ceramic insulating layer is coated between two adjacent corrugated Ni-Ti alloy single sheets. Each corrugated Ni-Ti alloy single sheet surface is etched with serpentine grooves, and an electric heating wire integrated array is embedded in the serpentine grooves. The electric heating wire integrated arrays between each layer are connected in parallel to the circuit.

[0016] Furthermore, the five mutually welded corrugated Ni-Ti alloy single sheets are continuously welded only at the 2mm position on the four peripheries to ensure mechanical coupling and coordinated action between layers, and no welding is performed in the middle area to allow each corrugated Ni-Ti alloy single sheet to deform independently to adapt to local pressure differences.

[0017] Further, the processing unit is configured to detect in real time the thickness value of the mouth of the food packaging bag detected by the high-precision laser displacement sensor; based on the thickness value detected in real time, establish a calculation formula to convert the thickness value into the pressure value that the upper die assembly needs to provide in real time; according to the calculated real-time required pressure value, calculate the heating temperature that the heating wire integrated array needs to provide through a mathematical model, and control the heating power of the heating wire integrated array through a PID algorithm; collect in real time the actual pressure detected by the thin film pressure sensor and trigger dynamic adjustment.

[0018] Further, detecting in real time the thickness value of the mouth of the food packaging bag detected by the high-precision laser displacement sensor includes:

[0019] Detect the thickness value of the mouth of the food packaging bag detected by the high-precision laser displacement sensor, and eliminate mechanical vibration noise through a Kalman filter, and output the average thickness value.

[0020] Further, based on the thickness value detected in real time, establishing a calculation formula to convert the thickness value into the pressure value that the upper die assembly needs to provide in real time includes:

[0021] For the output average thickness value, through establishing a calculation model, obtain a pressure-thickness mapping algorithm to convert the thickness value into the pressure value that the upper die assembly needs to provide in real time, and introduce a material hardness coefficient according to the material of the packaging bag to correct the calculation model.

[0022] Further, according to the calculated real-time required pressure value, calculating the heating temperature that the heating wire integrated array needs to provide through a mathematical model, and controlling the heating power of the heating wire integrated array through a PID algorithm includes:

[0023] According to the calculated real-time required pressure value, calculate the phase change state required by the corrugated Ni-Ti alloy laminations through a mathematical model, and according to the phase change state required by the corrugated Ni-Ti alloy laminations, calculate the target heating temperature that the heating wire integrated array needs to provide, and control the heating power of the heating wire integrated array through a PID algorithm.

[0024] Further, collecting in real time the actual pressure detected by the thin film pressure sensor and triggering dynamic adjustment includes:

[0025] Collect in real time the actual pressure applied to the food packaging bag detected by the thin film pressure sensor, and dynamically adjust the heating power until the absolute value of the difference between the actual pressure and the target pressure is less than or equal to 0.5 N, realizing closed-loop feedback of the pressure.

[0026] Compared with the prior art, the beneficial effects of the present invention:

[0027] By providing a heat-sealing assembly, the present application can adjust the pressing force on the opening of the food packaging bag in real time according to the thickness of the food packaging bag, so as to ensure that appropriate pressing forces can be obtained for food packaging bags of different thicknesses, avoid breaking the bag opening and causing deformation of the sealing area or air leakage due to improper sealing, reduce the rejection rate of the vacuum inflation heat-sealing device, further reduce the packaging cost, and improve the yield and packaging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 is a schematic left view structure diagram of the present invention;

[0030] Figure 3 is a schematic partial cross-sectional structure diagram of the present invention;

[0031] Figure 4 is an enlarged schematic structure diagram of the heat-sealing assembly of the present invention;

[0032] Figure 5 is a schematic cross-sectional structure diagram of the upper die assembly of the present invention.

[0033] Description of the reference numerals in the drawings:

[0034] 1, body; 2, bearing platform;

[0035] 3, heat-sealing assembly; 31, control motor; 32, connecting rod; 33, swing rod; 34, fixed seat; 35, driving rod; 36, high-precision laser displacement sensor;

[0036] 37, upper die assembly; 371, substrate; 372, high-temperature resistant silicone layer; 373, high-temperature resistant ceramic insulating layer; 374, electric heating wire integrated array; 375, corrugated Ni-Ti alloy laminate; 376, edge welding part; 377, air outlet; 378, thin-film pressure sensor; 379, heat conduction plate; 380, heat dissipation fin; 381, axial flow fan; 382, pressure balance port;

[0037] 38, heat-sealing strip; 39, lower die body;

[0038] 4, control panel; 5, air nozzle; 6, inert gas input port; 7, cylinder; 8, vacuum pump. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0040] Please refer to Figures 1 to 5 , a vacuum inflation heat-sealing device for food packaging, including a machine body 1. At the upper end of the front surface of the machine body 1, a bearing platform 2 is fixedly connected. Above the bearing platform 2 at the upper end of the machine body 1, there is a heat-sealing assembly 3 for heat-sealing food packaging bags.

[0041] The heat-sealing assembly 3 includes a control motor 31 fixedly connected to the inner wall of the machine body 1. The output end of the control motor 31 is fixedly connected to a connecting rod 32. One end of the connecting rod 32 is rotatably connected to a swing rod 33. The upper end of the swing rod 33 is rotatably connected to a driving rod 35. One end of the driving rod 35 is rotatably connected to a fixed seat 34 fixedly connected to the inner wall of the machine body 1. And the other end of the driving rod 35 is fixedly connected with an upper die assembly 37 for providing pressure to the mouth of the food packaging bag. A high-precision laser displacement sensor 36 is arranged above the upper die assembly 37. Corresponding to the position of the upper die assembly 37 on the upper surface of the bearing platform 2, a lower die body 39 is fixedly connected. A heat-sealing strip 38 is embedded in the upper end of the lower die body 39.

[0042] As Figures 1 to 3 shown, an air nozzle 5 is also movably arranged outside the upper end of the machine body 1, and the air nozzle 5 is arranged corresponding to the middle position of the heat-sealing assembly 3. A cylinder 7 is fixedly connected inside the machine body 1, and the output end of the cylinder 7 is fixedly connected to the air nozzle 5. A control panel 4 is arranged at the top of the front surface of the machine body 1. An inert gas input port 6 is also arranged on one outer surface of the machine body 1. A vacuum pump 8 is arranged at the bottom of the machine body 1. One end of the air nozzle 5 is respectively connected to the inert gas input port 6 and the vacuum pump 8 through pipelines, and the terminals of the two pipelines are jointly connected to the air nozzle 5 through a three-way valve.

[0043] In some embodiments, as Figure 5 shown, the upper die assembly 37 includes a substrate 371 fixedly connected to the other end of the driving rod 35. A cavity is opened at the bottom of the substrate 371. Around the upper end of the cavity, there are edge welding parts 376 and a corrugated Ni-Ti alloy laminate 375 is welded through the edge welding parts 376. A heat-conducting plate 379 is embedded in the top wall of the cavity, and a uniformly distributed thin-film pressure sensor 378 is embedded at the bottom of the heat-conducting plate 379. The bottom of the corrugated Ni-Ti alloy laminate 375 is adhesively connected with a high-temperature resistant silica gel layer 372.

[0044] A ventilation cavity is formed at the upper end of the substrate 371. The bottom wall of the ventilation cavity is provided with evenly distributed heat dissipation fins 380. Air outlet 377 and pressure balance port 382 are respectively formed at both ends of the ventilation cavity. An axial flow fan 381 is fixedly connected to a position on one side of the ventilation cavity near the pressure balance port 382. The height of the axial flow fan 381 inside the ventilation cavity is higher than that of the heat dissipation fins 380.

[0045] It also includes a processing unit for controlling the upper die assembly 37 to output an appropriate pressure.

[0046] The wavy Ni-Ti alloy laminated sheet 375 includes five layers of wavy Ni-Ti alloy single sheets connected by welding. A high-temperature resistant ceramic insulating layer 373 is coated between two adjacent wavy Ni-Ti alloy single sheets. Serpentine grooves are etched on the surface of each layer of wavy Ni-Ti alloy single sheet. Electric heating wire integrated arrays 374 are embedded in the serpentine grooves. The electric heating wire integrated arrays 374 of each layer are connected in parallel to the circuit.

[0047] The five layers of wavy Ni-Ti alloy single sheets connected by welding are continuously welded only at the 2-mm position of the four peripheries to ensure mechanical coupling and coordinated action between layers. Welding is not performed in the middle area to allow each layer of wavy Ni-Ti alloy single sheet to deform independently to adapt to local pressure differences.

[0048] When vacuum inflating and heat-sealing a food packaging bag, first place the packaging bag filled with food on the bearing platform 2. Control the cylinder 7 to extend through the control panel 4, insert the air nozzle 5 into the food packaging bag, and use the air nozzle 5 in cooperation with the vacuum pump 8 to evacuate the food packaging bag (this step and subsequent inflation, heat-sealing, and cooling and curing steps all require the heat-sealing assembly 3 to provide pressure on the bag mouth of the food packaging bag. The difference is that only in the heat-sealing step does the heat-sealing strip 38 work). After the evacuation is completed, the passage connecting the air nozzle 5 and the vacuum pump 8 of the three-way valve is closed, and the passage connecting the air nozzle 5 and the inert gas input port 6 is opened. It should be noted that the inert gas input port 6 is externally connected to an inert gas storage device (such as a nitrogen storage tank, etc.). Inert gas is input into the food packaging bag through the air nozzle 5. After the input of inert gas is completed, the control panel 4 controls the cylinder 7 to drive the air nozzle 5 to retract from the food packaging bag, and the heat-sealing step begins. The heat-sealing strip 38 is electrified to generate heat to heat-seal the bag mouth of the food packaging bag. After the heat-sealing is completed, the heat-sealing strip 38 is powered off, and the seal begins to cool and cure. After the curing is completed, the heat-sealing assembly 3 removes the pressure on the bag mouth of the food packaging bag to complete the entire vacuum inflating and heat-sealing operation.

[0049] When the heat-sealing assembly 3 applies pressure to the opening of the food packaging bag, the control panel 4 drives the control motor 31 to work. The control motor 31 drives the connecting rod 32 to rotate counterclockwise by a certain angle, and drives the driving rod 35 to rotate counterclockwise by a certain angle around the center point (the rotation connection point of the driving rod 35 and the fixed seat 34) through the swing rod 33 connected by rotation, thereby driving the upper mold assembly 37 to press down by a fixed distance to apply pressure to the opening of the food packaging bag.

[0050] To achieve the effect of providing appropriate pressure according to the thickness and material of the food packaging bag, a high-precision laser displacement sensor 36 is used to detect the thickness of the packaging bag, a calculation formula is established, and the thickness value is converted into the pressure value that the upper mold assembly 37 needs to provide in real time; according to the calculated real-time required pressure value, the heating temperature that the electric heating wire integrated array 374 needs to provide is calculated through a mathematical model, and the heating power of the electric heating wire integrated array 374 is controlled by the PID algorithm, thereby realizing the control of the phase change state of the corrugated Ni-Ti alloy laminated sheet 375;

[0051] If the high-precision laser displacement sensor 36 detects that the thickness of the packaging bag is relatively thin (such as an aluminum-plastic film with a thickness of 0.05 mm), the power of the electric heating wire integrated array 374 is controlled to be reduced to the lowest at this time, so that the temperature of the corrugated Ni-Ti alloy laminated sheet 375 drops to 40 degrees Celsius (at this time, the corrugated Ni-Ti alloy laminated sheet 375 presents a martensite phase), the laminated sheet is corrugated, the wave crest height increases, and the overall stiffness decreases (equivalent to the spring effect). During pressing, due to the elastic deformation (compression amount of 0.02 mm) of the high-temperature resistant silica gel layer 372, a gentle pressure of 5 N is applied to avoid damage and deformation of the opening of the packaging bag.

[0052] If the high-precision laser displacement sensor 36 detects that the thickness of the packaging bag is relatively thick (such as a co-extruded film with a thickness of 0.3 mm), the power of the electric heating wire integrated array 374 is controlled to be increased to the highest at this time, so that the temperature of the corrugated Ni-Ti alloy laminated sheet 375 rises to 80 degrees Celsius (at this time, the corrugated Ni-Ti alloy laminated sheet 375 presents an austenite phase), the corrugated Ni-Ti alloy laminated sheet 375 flattens, the layers are in close contact, the stiffness increases, the silica gel compression amount reaches 0.15 mm, and a pressure of 20 N is applied to ensure the tight fitting of the thick film layer.

[0053] If the thickness of the packaging bag is between the two, the heating temperature that the electric heating wire integrated array 374 needs to provide is calculated according to the mathematical model, thereby controlling the corrugated Ni-Ti alloy laminated sheet 375 to be in an appropriate phase change state, and then applying the corresponding pressure.

[0054] The actual pressure detected by the thin-film pressure sensor 378 is collected in real time. If the error is large, dynamic adjustment is triggered. During dynamic adjustment, if the actual pressure is too high, forced air cooling is started, the axial flow fan 381 is controlled to open, and the temperature dissipated by the heat dissipation fins 380 is blown out from the air outlet 377 for rapid heat dissipation, causing the wavy Ni-Ti alloy laminations 375 to transform towards the martensite phase and reducing the overall stiffness, thereby reducing the pressure; the pressure balance port 382 ensures that the hot air does not flow back; if the actual pressure is too low, the heating power of the electric heating wire integrated array 374 is controlled to increase, raising the heating temperature of the wavy Ni-Ti alloy laminations 375, causing the wavy Ni-Ti alloy laminations 375 to transform towards the austenite phase and increasing the overall stiffness, thereby increasing the pressure.

[0055] The processing unit is used to detect in real time the thickness value of the food packaging bag mouth detected by the high-precision laser displacement sensor 36; based on the thickness value detected in real time, a calculation formula is established to convert the thickness value into the pressure value that the upper die assembly 37 needs to provide in real time; according to the calculated real-time required pressure value, the heating temperature that the electric heating wire integrated array 374 needs to provide is calculated through a mathematical model, and the heating power of the electric heating wire integrated array 374 is controlled by the PID algorithm; the actual pressure detected by the thin-film pressure sensor 378 is collected in real time to trigger dynamic adjustment.

[0056] In some embodiments, detecting in real time the thickness value of the food packaging bag mouth detected by the high-precision laser displacement sensor 36 includes: detecting the thickness value of the food packaging bag mouth detected by the high-precision laser displacement sensor 36, and eliminating mechanical vibration noise through a Kalman filter to output the average thickness value.

[0057] By adopting the above technical solution, the high-precision laser displacement sensor 36 uses the triangulation method to detect the thickness value of the food packaging bag mouth, converts the analog signal into a digital quantity by using the built-in ADC, suppresses high-frequency noise through the built-in Kalman filter, removes the instantaneous disturbance caused by mechanical vibration, and outputs the average thickness value of the nearest 10 sampling points (10ms window).

[0058] In some embodiments, based on the thickness value detected in real time, establishing a calculation formula to convert the thickness value into the pressure value that the upper die assembly 37 needs to provide in real time includes:

[0059] For the output average thickness value, by establishing a calculation model, the pressure-thickness mapping algorithm is obtained as follows:

[0060]

[0061] where F T is the target pressure value, F min is the minimum pressure value, F max is the maximum pressure value, Hmax is the maximum thickness of the bag opening of the packaging bag, H min is the minimum thickness of the bag opening of the packaging bag, and h is the actually measured thickness of the bag opening of the packaging bag.

[0062] In this embodiment, F min is set to 5N, F max is set to 20N, H min is set to 0.05mm, H max is set to 0.3mm.

[0063] According to the above mathematical model, the target pressure value F T is calculated.

[0064] And for different material properties (such as hardness, elastic modulus), a correction coefficient is introduced to correct the calculation result. Specifically: F A = K × F T , where F A is the corrected target pressure value, and K is the material hardness coefficient:

[0065] For soft materials (such as PE film): K = 0.8 - 1.0;

[0066] For hard materials (such as aluminum-plastic composite film): K = 1.0 - 1.2.

[0067] In some implementations, according to the calculated real-time required pressure value, the heating temperature that the heating wire integrated array 374 needs to provide is calculated through a mathematical model, and the heating power of the heating wire integrated array 374 is controlled through a PID algorithm, including:

[0068] According to the calculated real-time required pressure value, the phase change state required by the corrugated Ni-Ti alloy laminate 375 is calculated through a mathematical model. According to the phase change state required by the corrugated Ni-Ti alloy laminate 375, the heating target temperature that the heating wire integrated array 374 needs to provide is calculated, and the heating power of the heating wire integrated array 374 is controlled through a PID algorithm.

[0069] By adopting the above technical solution, the calculated real-time required pressure value is substituted into the following mathematical model:

[0070]

[0071] Among them, E rep is the equivalent modulus of the corrugated Ni-Ti alloy laminate 375 under the target pressure; F Ais the target pressure value; n is the number of layers of the corrugated Ni-Ti alloy laminations 375, which is taken as 5 layers in this embodiment; A is the cross-sectional area of a single layer (A = W × t, in this embodiment, W (length) = 50 mm, t (width) = 0.2 mm); L is the effective length, which is taken as 50 mm; δ is the deformation of the pressing plate (determined by the thickness of the bag mouth and the pressing displacement).

[0072] Using the equivalent modulus E of the corrugated Ni-Ti alloy laminations 375 at the calculated target pressure value rep , establish the calculation formula:

[0073] E rep = E M ×V M + E A (1 - V M )

[0074] where V M is the martensite volume fraction (commonly used as a characterization of the phase transformation morphology); E M is the maximum equivalent stiffness, which is set to 50 GPa in the embodiment of this application, and E A is the minimum equivalent stiffness, which is set to 1 GPa in the embodiment of this application, and both are calibrated by tensile tests.

[0075] According to the obtained calculation result V M , substitute it into the following formula:

[0076]

[0077] where V M is the martensite volume fraction, T is the target temperature corresponding to the target pressure, M f is the martensite finish temperature (40 degrees Celsius); K M is the phase transformation rate constant (typical value is 0.1 - 0.3).

[0078] According to the above formula, substituting the relevant known data, the target temperature T can be obtained.

[0079] Establish a PID algorithm model:

[0080]

[0081] where P is the heating power required for the electric heating wire integrated array 374 corresponding to the target temperature T; T is the target temperature; T real is the current heating temperature; t is the control period; K P is the proportionality coefficient (typical range 10 - 100), which reflects the response intensity to the current error; K I is the integral coefficient (typical range 0.01 - 1), which is used to eliminate the steady-state error; K dis the differential coefficient (typical range 0.1 - 10), which suppresses temperature fluctuations and improves stability.

[0082] The heating power of the heating wire integrated array 374 at the target temperature is calculated through the above algorithm.

[0083] In some implementations, the actual pressure detected by the thin-film pressure sensor 378 is collected in real time to trigger dynamic adjustment, including:

[0084] The actual pressure exerted on the food packaging bag detected by the thin-film pressure sensor 378 is collected in real time, and the heating power is dynamically adjusted until the absolute value of the difference between the actual pressure and the target pressure is less than or equal to 0.5 N, achieving closed-loop feedback of pressure.

[0085] By adopting the above technical solution, the actual pressure detected by the thin-film pressure sensor 378 is compared with the target pressure value, and combined with:

[0086] |F R -F A |≤0.5N

[0087] A judgment is made. If the result is greater than 0.5 N, dynamic adjustment is required. If the result is less than or equal to 0.5 N, it means that dynamic adjustment is not required, and the currently provided actual pressure value is close to the target pressure value.

[0088] As described above, it is only a preferred specific implementation manner of the present invention; however, the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its improved concept, makes equivalent substitutions or changes, and all should be covered by the protection scope of the present invention.

Claims

1. A vacuum inflation heat sealing device for food packaging, comprising a machine body (1), characterized in that: A base table (2) is fixedly connected to the upper end position of the front surface of the machine body (1), and a heat-sealing assembly (3) for heat-sealing a food packaging bag is provided above the base table (2) at the upper end of the machine body (1). The heat-sealing assembly (3) includes a control motor (31) fixedly connected to the inner wall of the machine body (1). The output end of the control motor (31) is fixedly connected to a connecting rod (32). One end of the connecting rod (32) is rotatably connected to a swing rod (33). The upper end of the swing rod (33) is rotatably connected to a driving rod (35). One end of the driving rod (35) is rotatably connected to a fixed seat (34) fixedly connected to the inner wall of the machine body (1), and the other end of the driving rod (35) is fixedly connected with an upper die assembly (37) for providing pressure to the mouth of the food packaging bag. A high-precision laser displacement sensor (36) is provided at the upper end of the upper die assembly (37). A lower die body (39) is fixedly connected to the upper surface of the base table (2) corresponding to the position of the upper die assembly (37), and a heat-sealing strip (38) is embedded in the upper end of the lower die body (39).

2. The vacuum inflation heat-sealing device for food packaging according to claim 1, wherein: An air nozzle (5) is also movably provided to the outside at the upper end inside the machine body (1), and the air nozzle (5) is arranged corresponding to the middle position of the heat-sealing assembly (3). A cylinder (7) is fixedly connected inside the machine body (1), and the output end of the cylinder (7) is fixedly connected to the air nozzle (5). A control panel (4) is provided at the top of the front surface of the machine body (1). An inert gas inlet (6) is also provided on the outer surface of one side of the machine body (1). A vacuum pump (8) is provided at the bottom of the machine body (1), and one end of the air nozzle (5) is respectively connected to the inert gas inlet (6) and the vacuum pump (8) through pipes. The terminals of the two pipes are jointly connected to the air nozzle (5) through a three-way valve.

3. The vacuum inflation heat-sealing device for food packaging according to claim 1, characterized in that: The upper die assembly (37) includes a substrate (371) fixedly connected to the other end of the driving rod (35). A cavity is formed at the bottom of the substrate (371). Peripheral edge welding parts (376) are provided around the upper end of the cavity and are welded to connect a corrugated Ni-Ti alloy laminate (375) through the edge welding parts (376). A heat-conducting plate (379) is embedded in the top wall of the cavity, and a uniformly distributed thin-film pressure sensor (378) is embedded at the bottom of the heat-conducting plate (379). A high-temperature resistant silica gel layer (372) is adhesively connected to the bottom of the corrugated Ni-Ti alloy laminate (375). A ventilation cavity is formed at the upper end of the substrate (371). Heat dissipation fins (380) are provided on the bottom wall of the ventilation cavity at uniform intervals. An air outlet (377) and a pressure balance port (382) are respectively formed at both ends of the ventilation cavity. An axial flow fan (381) is fixedly connected to the position of the ventilation cavity close to the pressure balance port (382) on one side. The height of the axial flow fan (381) inside the ventilation cavity is higher than the height of the heat dissipation fins (380). It also includes a processing unit for controlling the upper die assembly (37) to output an appropriate pressure.

4. The vacuum inflation heat-sealing device for food packaging according to claim 3, characterized in that: The wavy Ni-Ti alloy laminated sheet (375) includes five layers of wavy Ni-Ti alloy single sheets that are welded to each other. A high-temperature resistant ceramic insulating layer (373) is coated between two adjacent wavy Ni-Ti alloy single sheets. The surface of each layer of the wavy Ni-Ti alloy single sheet is etched with serpentine grooves, and an integrated array of heating wires (374) is embedded in the serpentine grooves. The integrated arrays of heating wires (374) of each layer are connected in parallel to the circuit.

5. The vacuum inflation heat-sealing device for food packaging according to claim 4, wherein: The five layers of wavy Ni-Ti alloy single sheets that are welded to each other are continuously welded only at the 2-mm position of the four peripheries to ensure mechanical coupling and coordinated action between layers. The middle area is not welded to allow each layer of the wavy Ni-Ti alloy single sheet to deform independently to adapt to local pressure differences.

6. The vacuum inflation heat-sealing device for food packaging according to claim 4, wherein: The processing unit is used to detect in real time the thickness value of the mouth of the food packaging bag detected by the high-precision laser displacement sensor (36); based on the thickness value detected in real time, establish a calculation formula to convert the thickness value into the pressure value that the upper die assembly (37) needs to provide in real time; according to the calculated real-time required pressure value, calculate the heating temperature that the integrated array of heating wires (374) needs to provide through a mathematical model, and control the heating power of the integrated array of heating wires (374) through a PID algorithm; collect in real time the actual pressure detected by the thin-film pressure sensor (378) and trigger dynamic adjustment.

7. The vacuum inflation heat sealing device for food packaging according to claim 6, wherein: Detecting in real time the thickness value of the mouth of the food packaging bag detected by the high-precision laser displacement sensor (36) includes: Detecting the thickness value of the mouth of the food packaging bag detected by the high-precision laser displacement sensor (36), and eliminating mechanical vibration noise through a Kalman filter to output the average thickness value.

8. The vacuum inflation heat-sealing device for food packaging according to claim 6, wherein: Based on the thickness value detected in real time, establishing a calculation formula to convert the thickness value into the pressure value that the upper die assembly (37) needs to provide in real time includes: For the output average thickness value, through establishing a calculation model, obtaining a pressure-thickness mapping algorithm to convert the thickness value into the pressure value that the upper die assembly (37) needs to provide in real time, and introducing a material hardness coefficient according to the material of the packaging bag to correct the calculation model.

9. The vacuum inflation heat-sealing device for food packaging according to claim 6, wherein: According to the calculated real-time required pressure value, calculating the heating temperature that the integrated array of heating wires (374) needs to provide through a mathematical model, and controlling the heating power of the integrated array of heating wires (374) through a PID algorithm includes: According to the calculated real-time required pressure value, calculating the phase change state required by the wavy Ni-Ti alloy laminated sheet (375) through a mathematical model. According to the phase change state required by the wavy Ni-Ti alloy laminated sheet (375), calculating the target heating temperature that the integrated array of heating wires (374) needs to provide, and controlling the heating power of the integrated array of heating wires (374) through a PID algorithm.

10. The vacuum inflation heat sealing device for food packaging according to claim 6, characterized in that: Collecting in real time the actual pressure detected by the thin-film pressure sensor (378) and triggering dynamic adjustment includes: Collecting in real time the actual pressure exerted on the food packaging bag detected by the thin-film pressure sensor (378), and dynamically adjusting the heating power until the absolute value of the difference between the actual pressure and the target pressure is less than or equal to 0.5 N to achieve closed-loop feedback of the pressure.

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