Degradable plastic injection molding machine and injection molding method thereof

Abstract

The application provides a degradable plastic injection molding machine, comprising: an injection molding machine base, the upper part of which is provided with a dust cover; a mold closing assembly, which is located in a closed space surrounded by the injection molding machine base and the dust cover, the mold closing assembly comprises an injection molding fixed mold and an injection molding movable mold, the injection molding fixed mold remains relatively stationary with the injection molding machine base, the injection molding movable mold can move on the injection molding machine base, and the injection molding fixed mold and the injection molding movable mold can cooperate to form an injection molding cavity for accommodating degradable plastic, a plurality of detection assemblies are uniformly distributed on the injection channel, so that temperature and pressure data at different positions can be obtained in real time, the pressure difference between adjacent detection areas is calculated, and an area with insufficient fluidity can be identified, a mapping relationship between pressure and temperature requirements is established, so that the heating element can additionally heat the area with insufficient fluidity, the degradable plastic in the area with insufficient fluidity can be softened, the viscosity of the degradable plastic is reduced, and the degradable plastic can flow more uniformly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of injection molding, in particular to a degradable plastic injection molding machine and an injection molding method thereof. BACKGROUND

[0002] Degradable materials are mostly non-Newtonian fluids with high viscosity and poor flowability, which are difficult to fully fill thin-walled or complex structures by relying on the axial injection pressure of traditional injection molding machines, and are prone to cause defects such as short shots and sink marks. Moreover, the screw of the injection molding machine improves the melting efficiency by high shear force, but the degradable material is sensitive to shear, and high shear force will cause material oxidation, viscosity rise and even gelation, thereby reducing the mechanical properties of the product.

[0003] Chinese Patent No. CN109702976B discloses an injection molding machine for metal powder melt injection, which comprises a rack, a mold clamping system, an injection system and a control system for opening and closing the mold installed thereon; a plasticizing assembly for injecting the melt into the cavity of the mold, the plasticizing assembly comprising a barrel and an injection screw arranged in the barrel; and a control system connected with the mold clamping system and the injection system for controlling the opening and closing of the mold of the mold clamping system and the pulse rotation and pulse axial reciprocating motion of the injection screw in the barrel during injection. By setting the control system to control the pulse rotation and pulse axial reciprocating motion of the injection screw in the barrel during injection, the free volume between macromolecules in the metal powder melt can be increased and the mutual separation effect can be strengthened, thereby promoting the disentanglement of macromolecular chains and segments, reducing the viscosity and elasticity of the metal powder melt, and strengthening the flowability.

[0004] Chinese Patent No. CN118322508B discloses an intelligent temperature detection device for an injection molding machine, which is applied to the technical field of temperature detection devices and comprises a machine body and a temperature detection system. The machine body is fixedly connected with a barrel, a support platform, an injection fixed mold and a cover shell at the top. An injection movable mold is arranged on the left side of the injection fixed mold. An ejection device is arranged in the injection movable mold. The injection movable mold is matched with the injection fixed mold. A pull rod is hingedly connected to the left side of the injection movable mold. A mold clamping oil cylinder is fixedly connected to the left side of the pull rod. The cover shell is arranged above the mold clamping oil cylinder. A control console is fixedly connected to the right side of the injection fixed mold. A discharge port is formed in the machine body and located below the injection fixed mold and the injection movable mold. An infrared detector is fixedly connected to the machine body and located above the discharge port. A pressure sensor is arranged in the machine body and located at the discharge port. The device solves the problem of unstable temperature of the injection molding machine controlled by humans.

[0005] As can be seen from the above, the injection pressure and temperature of traditional injection molding machines are independently controlled, that is, the temperature is only used for plasticization and the pressure is only used for pushing. It is difficult to achieve uniform injection of complex melts such as non-Newtonian fluids, which easily leads to unstable injection quality of products. Therefore, there is an urgent need for a biodegradable plastic injection molding machine and its injection method. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a biodegradable plastic injection molding machine and its injection method, which solves the problem that traditional injection molding machines have independent control over injection pressure and temperature. That is, temperature is only used for plasticization and pressure is only used for pushing, making it difficult to achieve uniform injection of complex melts such as non-Newtonian fluids, and easily causing unstable injection quality of products.

[0007] According to a first aspect of the present disclosure, a preferred embodiment of the present invention provides a biodegradable plastic injection molding machine, comprising:

[0008] The injection molding machine base has a dustproof cover on its upper part;

[0009] A mold clamping assembly is located within a sealed space enclosed by the injection molding machine base and a dust cover. The mold clamping assembly includes a fixed injection mold and a moving injection mold. The fixed injection mold remains relatively stationary with respect to the injection molding machine base, while the moving injection mold can move on the injection molding machine base. The fixed injection mold and the moving injection mold can cooperate to form an injection cavity for accommodating biodegradable plastic.

[0010] The injection extruder has multiple heating elements distributed along the injection direction of the biodegradable plastic on the side wall of the injection channel.

[0011] Injection flowability monitoring components are used to acquire temperature and pressure values ​​at different locations along the injection direction of biodegradable plastics.

[0012] The injection flowability monitoring component includes a detection array evenly distributed on the injection channel, and each detection array includes at least one temperature detection element and at least one pressure detection element.

[0013] In one embodiment, the injection channel of the injection extruder passes through the injection mold and is connected to the injection cavity, and the portion of the injection channel located inside the injection cavity is equipped with an injection nozzle.

[0014] In one embodiment, a mold-closing cylinder is provided on one side of the injection molding moving mold and is fixed to the injection molding machine base. The mold-closing cylinder drives the injection molding moving mold to adjust the distance between it and the injection molding stationary mold through a telescopic bracket. A demolding cylinder is fixed on the side of the injection molding moving mold away from the injection molding stationary mold. The output end of the demolding cylinder is fixed with a top mold bracket that can extend into the injection cavity.

[0015] In an embodiment, the screw in the injection channel of the injection extruder is divided into a feeding section, a compression section and a metering section, the length-diameter ratio of the feeding section is 2.5, the screw channel depth is 0.25d, the length-diameter ratio of the compression section is 5, the screw channel depth gradually decreases from 0.25d to 0.15D, and the length-diameter ratio of the metering section is 4, the screw channel depth is 0.15d.

[0016] In an embodiment, the basic output power of the heating element gradually decreases along the injection direction of the degradable plastic, and the heating temperature range of the heating element is 160-190℃.

[0017] According to a second aspect of the embodiments of the present disclosure, the present application provides an injection molding method of the degradable plastic injection molding machine, which comprises the following steps:

[0018] S100: sorting the detection groups at different positions in different regions along the injection path, and dividing the injection channel into different detection regions;

[0019] S200: calculating the average value of the detection temperature value of the temperature detection element in the detection region in the standby state of the injection extruder, and controlling the heating element to execute heat output if the average value of the detection temperature value is lower than the preset standard;

[0020] S300: calculating the average value of the detection pressure value of the pressure detection element and the average value of the detection temperature value of the temperature detection element in the detection region in the output state of the injection extruder, and controlling the heating element to change the heat output power according to the difference between the average pressures of different detection regions;

[0021] The step S300 comprises:

[0022] S301: calculating the pressure difference value of the average pressure of adjacent detection regions, and recording the region whose pressure difference value exceeds the average value as a region with insufficient fluidity;

[0023] S302: converting the pressure excess amount of the region with insufficient fluidity into the heat compensation power required by the region, and transmitting the heat compensation power to the degradable plastic through the heating element.

[0024] In an embodiment, the formula for converting the pressure excess amount of the region with insufficient fluidity into the heat compensation power required by the region in the step S302 is:

[0025]

[0026] Wherein, F is the actual output power, A is the basic output power, k is the heat compensation coefficient, P is the pressure excess amount of the region with insufficient fluidity, V is the volume of the region with insufficient fluidity, and t is the heating time.

[0027] In an embodiment, if the average of the detected temperature values is lower than the preset standard, the formula for controlling the heating element to execute the heat output in the step S200 is:

[0028]

[0029] wherein N is the actual output power; S is the basic output power; M is the temperature compensation coefficient; and L is the difference between the preset standard temperature and the average temperature of the detection area.

[0030] From the above technical solution, the degradable plastic injection molding machine and the injection molding method provided by the present application can have the following beneficial effects:

[0031] The present disclosure can obtain temperature and pressure data at different positions in real time by uniformly distributing multiple detection combinations on the injection channel, and can identify the area with insufficient fluidity by calculating the pressure difference of adjacent detection areas, so that the heating element can additionally heat the area with insufficient fluidity, and the degradable plastic in the area with insufficient fluidity can be softened, thereby reducing its viscosity, making it flow more uniformly, better filling the cavity with thin walls or complex structure, avoiding defects such as short shot and sink marks, improving the appearance quality and mechanical properties of the product, and reducing the scrap rate.

[0032] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the specific embodiments of the present application, the drawings required for use in the specific embodiments or prior art description will be briefly introduced below. In all the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0034] Figure 1 An appearance view of the degradable plastic injection molding machine provided by the present application;

[0035] Figure 2 A side sectional view of the degradable plastic injection molding machine provided by the present application;

[0036] Figure 3 A flowchart of the injection molding method of the degradable plastic injection molding machine provided by the present application;

[0037] Figure 4 A flowchart of step S300 in the injection molding method of the degradable plastic injection molding machine provided by the present application.

[0038] Reference signs: 1, injection molding machine base; 11, dust cover; 2, mold closing assembly; 21, injection molding fixed mold; 22, injection molding movable mold; 221, mold closing oil cylinder; 222, telescopic support; 223, demolding oil cylinder; 224, top mold support; 3, injection molding extruder; 31, heating element; 32, injection molding nozzle; 4, injection molding fluidity monitoring assembly; 41, temperature detection element; 42, pressure detection element. DETAILED DESCRIPTION

[0039] The embodiments of the patent technical solutions of the present application will be described in detail below in conjunction with the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0040] Embodiment, please refer to Figures 1-2As shown, the embodiment provides a kind of degradable plastics injection molding machine, including injection molding machine base 1, mold assembly 2, injection extruder 3 and injection flow monitoring assembly 4, the injection flow monitoring assembly 4 includes PLC control terminal, the PLC control terminal is electrically connected with the electric control element in mold assembly 2, injection extruder 3, to be able to automatically realize mold clamping, injection molding, demolding process: the upper portion of the injection molding machine base 1 is equipped with dust cover 11, the edge of dust cover 11 is fixed with injection molding machine base 1, can form a space isolated from external connection, to reduce the influence of environment on injection, and dust cover 11 side is also hinged with door, to facilitate demolding and taking out; The mold assembly 2 is located in the closed space surrounded by injection molding machine base 1 and dust cover 11, the mold assembly 2 includes injection fixed mold 21 and injection movable mold 22, the injection fixed mold 21 keeps relatively stationary with injection molding machine base 1, the injection movable mold 22 can move on injection molding machine base 1, and the injection fixed mold 21 and injection movable mold 22 can cooperate to form injection cavity for containing degradable plastics, the adjacent side of injection fixed mold 21 and injection movable mold 22 is provided with a half mold cavity, when mold clamping, half mold cavity combines to form complete and closed injection cavity, when demolding, half mold cavity separates, so that product can be directly taken out, it is worth mentioning that the half mold cavity cavity wall top of injection fixed mold 21 is equipped with the vacuumizing pipe being communicated with vacuum generator, to facilitate the air in injection cavity being evacuated after injection fixed mold 21 and injection movable mold 22 mold clamping, to avoid the quality defect of product;The injection channel side wall of injection extruder 3 is distributed with a plurality of heating elements 31 along the direction of degradable plastics injection, the heating element 31 is annular structure and is nested in the outer wall of the cylindrical injection channel of injection extruder 3, which is in close contact with the injection channel, can well transfer heating heat to degradable plastics, specifically, heating element 31 generates heat by passing electric resistance wire, and electric resistance wire is tightly wrapped in the heat-conducting shell of heating element 31, can transfer heat to degradable plastics in injection channel through heat-conducting shell, and electric heating mode can accurately control heating temperature, and can quickly adjust heating power as needed, it should be noted that injection extruder 3 is also provided with feeding hopper being communicated with injection channel and driving motor for driving internal screw of injection channel;The injection flow monitoring assembly 4 is used to obtain temperature value and pressure value at different positions of injection channel along the direction of degradable plastics injection.The injection flow monitoring assembly 4 comprises detection combinations uniformly distributed on the injection channel, each detection combination comprising at least one temperature detection element 41 and at least one pressure detection element 42, the temperature detection element 41 can be a thermistor, and the pressure detection element 42 can be a pressure-sensitive resistor, wherein the thermistor is arranged to tightly contact the outer wall of the injection channel, and the pressure-sensitive resistor is arranged to directly contact the degradable plastic on the inner wall of the injection channel, specifically, the detection combination and the heating element 31 are arranged in a spaced distribution manner, which can reduce the direct influence of the heating element 31 on the temperature detection element 41, effectively guarantee the data collection accuracy, and the temperature detection element 41 and the pressure detection element 42 are electrically connected with the PLC control terminal, so that the PLC control terminal can timely adjust the heating state or the pressure increasing state of the injection extruder 3 according to the temperature value and the pressure value.

[0041] In an embodiment, the injection channel of the injection extruder 3 is communicated with the injection cavity after passing through the injection mold 21, and the part of the injection channel located in the injection cavity is provided with the injection nozzle 32.

[0042] Specifically, the degradable plastic can smoothly enter the injection cavity through the injection channel, and the injection molding process can be completed, the injection nozzle 32 can accurately control the injection speed and flow of the degradable plastic, avoid product defects caused by uneven flow, such as short shot or shrink mark, better fill the cavity of thin-walled or complex structure, and reduce the molding problems caused by insufficient flow.

[0043] In an embodiment, the injection mold 22 is provided with a mold clamping oil cylinder 221 fixed with the injection machine base 1 on one side, the mold clamping oil cylinder 221 drives the injection mold 22 to adjust the distance between the injection mold 22 and the injection mold 21 through the telescopic support 222, and the injection mold 22 is fixed with a demolding oil cylinder 223 on the side away from the injection mold 21, and the output end of the demolding oil cylinder 223 is fixed with a top die support 224 which can extend into the injection cavity.

[0044] Specifically, the mold clamping oil cylinder 221 drives the injection mold 22 to move through the telescopic support 222, so that the injection mold 22 can smoothly move along the predetermined track, thereby adjusting the distance between the injection mold 22 and the injection mold 21, so that the injection mold 22 can tightly contact the injection mold 21 to form the injection cavity, after the injection is completed, the injection mold 22 can be separated from the injection mold 21 to prepare for demolding, and the demolding oil cylinder 223 drives the top die support 224 to enter the injection cavity, thereby ejecting the molded product from the cavity, and the demolding process can be completed.

[0045] In an embodiment, the screw in the injection channel of the injection molding extruder 3 is divided into a feeding section, a compression section and a metering section, the length-diameter ratio of the feeding section is 2.5, the screw channel depth is 0.25d, the length-diameter ratio of the compression section is 5, the screw channel depth gradually decreases from 0.25d to 0.15d, and the length-diameter ratio of the metering section is 4, and the screw channel depth is 0.15d;

[0046] Specifically, the main role of the feeding section is to send the degradable plastic particles from the hopper into the injection channel and start preheating and preliminary plasticizing, and the length-diameter ratio is small (2.5), the feeding section is relatively short, which helps to quickly send the plastic particles into the subsequent compression section, and the deep screw channel depth (0.25d) can accommodate more plastic particles, ensuring the efficiency of feeding; the main role of the compression section is to further plasticize and compress the plastic, and as the screw channel depth gradually decreases, the pressure of the plastic in the screw gradually increases, which helps the melting and uniform mixing of the plastic, and the length-diameter ratio is 5, the compression section is relatively long, which can provide enough space and time to complete the compression and plasticization process of the plastic, and can effectively avoid the problems of excessive shearing or uneven plasticization of the plastic during the compression process; the main role of the metering section is to ensure that the plastic has uniform temperature and pressure before injection, and can enter the injection molding cavity with stable flow, and the shallow screw channel depth (0.15d) helps the uniform distribution and stable flow of the plastic in the screw, and the length-diameter ratio is 4, the length of the metering section is moderate, which can ensure that the plastic reaches the ideal plasticization state before entering the injection channel.

[0047] In an embodiment, the basic output power of the heating element 31 gradually decreases along the injection direction of the degradable plastic, and the heating temperature range of the heating element 31 is 160-190℃;

[0048] Specifically, the temperature range of 160-190℃ can ensure that the plastic is fully melted during the injection process, while avoiding problems such as material oxidation, viscosity sudden rise or gelation caused by too high temperature, and the temperature of the multiple heating elements 31 changes in a gradient manner, so that the temperature at the starting position (close to the feeding hopper) of the injection channel is lower than the temperature at the end position (close to the injection molding nozzle 32) of the injection channel, and the temperature in the injection channel gradually decreases from the starting position to the end position. Since the plastic particles need a higher temperature to start melting and plasticizing when they just enter the material, the heating element 31 at the starting position needs higher heating power, and at the end of the injection channel, the plastic has been basically melted, at this time, a lower temperature is needed to maintain its fluidity, so as to avoid excessive heating leading to material performance degradation or decomposition, therefore, the heating element 31 at the end position needs to appropriately reduce the heating power.

[0049] Please refer to Figures 1-4 The application also provides an injection molding method of the degradable plastic injection molding machine, which comprises the following steps:

[0050] S100: Combining the detection groups of different positions in sequence by region along the injection path, and dividing the injection channel into different detection regions;

[0051] In this implementation, the injection channel is divided into different detection regions, and each detection region contains one or more detection groups, so that the injection molding machine can comprehensively monitor the temperature and pressure changes in the injection process, and can more accurately analyze the temperature and pressure state of each region.

[0052] S200: In the standby state of the injection extruder 3, the average value of the detection temperature value of the temperature detection element 41 in the detection region is calculated, and if the average value of the detection temperature value is lower than the preset standard, the heating element 31 is controlled to perform heat output;

[0053] In this implementation, the plurality of temperature detection elements 41 are distributed equidistantly around the injection channel, and the average value of the detection temperature value of the temperature detection element 41 is calculated to improve the accuracy of the data. When the injection extruder 3 does not perform output, if the average value of the detection temperature value is greater than or equal to the preset standard, it indicates that the degradable plastic has reached the required viscosity requirement, and at this time the heating element 31 does not perform heat output. If the average value of the detection temperature value is lower than the preset standard, it indicates that the degradable plastic has not reached the required viscosity requirement, and the heating element 31 needs to be heated to reduce the viscosity of the degradable plastic to meet the flowability requirement of the degradable plastic injection molding.

[0054] S300: In the output state of the injection extruder 3, the average value of the detection pressure value of the pressure detection element 42 in the detection region and the average value of the detection temperature value of the temperature detection element 41 are calculated, and the heating element 31 is controlled to change the heat output power according to the difference between the average pressures of different detection regions;

[0055] In the implementation, the plurality of pressure detection elements 42 are distributed equidistantly around the injection channel in a circumferential direction, and the accuracy of the data can be improved by calculating the average of the pressure values detected by the pressure detection elements 42. In the output state of the injection extruder 3, if the difference between the average pressures of different detection areas is large, it indicates that the degradable plastic does not meet the required viscosity requirement, which leads to the existence of quality distribution imbalance in the degradable plastic. If the difference between the average pressures of different detection areas is not large, it indicates that the degradable plastic meets the required viscosity requirement and satisfies the requirement of flowability. It is worth noting that whether the difference between the average pressures of different detection areas exceeds the range value depends on the safety standards of different injection materials. On the other hand, the difference between the average pressures of different detection areas is also affected by the screw structure in the injection channel of the injection extruder 3. Since the screw is divided into a feeding section, a compression section and a metering section, and the structure design of each section of the screw is different, the pressure of the plastic in the injection channel changes with the position, forming a pressure gradient. This pressure gradient is an inevitable phenomenon in the normal injection molding process, but if the pressure gradient is too large, it may cause uneven plastic flow, thereby affecting the molding quality. Since the feeding section has a deep screw groove, the filling amount of the plastic in this area is large, but the pressure is relatively low. This is because the plastic has not been fully melted, and the flowability is poor, and the depth of the screw groove is large, and the compression effect on the plastic is small. As the depth of the screw groove gradually decreases, the pressure of the plastic in the screw gradually increases. This is because the reduction of the screw groove depth makes the plastic receive greater compression force, and the melting degree of the plastic increases, the flowability improves, but the pressure also rises accordingly. Therefore, the pressure in the compression section is usually significantly higher than that in the feeding section; the pressure in the metering section is relatively stable, but since the depth of the screw groove is shallow, the plastic receives a large compression force, so the pressure is usually higher than that in the compression section. In addition, the pressure distribution in the metering section is relatively uniform, which helps to ensure that the plastic has good flowability and temperature consistency before entering the injection cavity; the transition area is the transition area between different functional sections of the screw, and its design has a significant impact on the flow of plastic, pressure distribution and final molding quality. Therefore, the allowable range of the difference between the average pressures of the detection areas around the transition area is large.

[0056] The step S300 includes:

[0057] S301: Calculate the pressure difference value of the average pressure of the adjacent detection area, and record the area with a pressure difference value exceeding the average value as a flowability insufficient area;

[0058] In this implementation, if the pressure of a certain area is significantly higher than that of its adjacent area, it indicates that the plastic flowability of this area may be poor, and more heat is needed to reduce its viscosity. As another implementable solution of the present embodiment, by establishing a coordinate system between different detection areas and their average pressures, the coordinate points of each detection area and its average pressure can be connected to each other to obtain a change curve of the average pressure, and the fluctuation degree of the change curve is analyzed by AI, wherein the area with too steep fluctuation degree is the area with insufficient flowability.

[0059] S302: converting the pressure excess of the area with insufficient flowability into the heat compensation power required by the area, and transmitting the heat compensation power to the degradable plastic through the heating element 31;

[0060] Specifically, the viscosity of the degradable plastic decreases with the increase of temperature. When the pressure of a certain area is too high, it indicates that the viscosity of the degradable plastic in this area is too high, and the flowability is poor. In order to improve the flowability, the temperature of this area needs to be increased. By reducing the viscosity of the area with insufficient flowability and improving its flowability, injection defects such as short shot and sink mark can be reduced, and the appearance quality and mechanical properties of the product can be improved. Once the area with insufficient flowability is identified, the output power of the heating element 31 in the corresponding area needs to be increased within a set heating time, and the greater the pressure excess, the greater the heat compensation power required, and the output power of the heating element 31 will increase accordingly.

[0061] In an embodiment, the formula for converting the pressure excess of the area with insufficient flowability into the heat compensation power required by the area in step S302 is:

[0062]

[0063] wherein F is the actual output power, which is the total power required by the heating element 31 in the area with insufficient flowability, including the basic output power and the additional heat compensation power;

[0064] A is the basic output power, which is the heating power provided by the heating element 31 in the normal working state, used to maintain the basic temperature in the injection channel; k is the heat compensation coefficient, which is a proportional factor for converting the pressure excess into the heat compensation power, and its value depends on the thermal sensitivity of the material and the specific design of the injection molding machine;

[0065] P is the pressure excess of the area with insufficient flowability, which is the difference between the pressure of the area with insufficient flowability and the pressure of the adjacent area, indicating the resistance of the area;

[0066] V is the volume of the underflow area, which is the size of the underflow area, used to calculate the amount of plastic that needs to be heated; t is the heating time, which is the time for the heating element 31 to provide heat compensation power, if the heating time is longer, the required heat compensation power will decrease, on the contrary, if the heating time is shorter, the required heat compensation power will increase;

[0067] Through this formula, the injection molding machine can accurately calculate the heat compensation power required by the underflow area, so as to accurately control the output power of the heating element, which allows the injection molding machine to adapt to the actual injection molding conditions and material properties, and can avoid the decline of material performance or injection defects caused by uneven pressure by dynamically adjusting the heat output power of the heating element, improve the flowability of the underflow area by reducing its viscosity, reduce injection defects such as short shot and sink mark, and improve the appearance quality and mechanical properties of the product. Through automatic identification and processing of the underflow area, the injection molding machine can shorten the injection molding cycle and improve the production efficiency.

[0068] In an embodiment, if the average value of the detected temperature is lower than the preset standard in step S200, the formula for controlling the heating element 31 to execute heat output is:

[0069]

[0070] Wherein, N is the actual output power, which is the total power required by the heating element 31 in standby state, including basic output power and additional temperature compensation power;

[0071] S is the basic output power, which is the heating power provided by the heating element 31 in normal working state, used to maintain the basic temperature in the injection channel; M is the temperature compensation coefficient, which is a proportional factor used to convert the temperature difference into additional heating power, its value depends on the heat sensitivity of the material and the specific design of the injection molding machine;

[0072] L is the difference between the preset standard temperature and the average temperature of the detected area, which represents the gap between the current temperature and the ideal temperature, used to calculate the additional heat required, through this formula, the injection molding machine can accurately calculate the heat output required in standby state, so as to accurately control the output power of the heating element 31, this formula allows the injection molding machine to adapt to the actual temperature detection results;

[0073] By dynamically adjusting the heat output power of the heating element 31, the temperature in the injection channel can be ensured to reach the expected standard, avoiding the performance degradation or injection defects caused by uneven temperature. By ensuring the uniformity of the temperature in the injection channel, the molding quality of the degradable plastic product can be improved, the injection defects can be reduced, and the appearance quality and mechanical properties of the product can be improved. By automatically identifying and processing the problem of uneven temperature, the injection molding machine can shorten the preheating time and improve the production efficiency.

[0074] Working principle: By uniformly distributing multiple detection combinations on the injection channel, real-time temperature and pressure data at different positions can be obtained. By calculating the pressure difference between adjacent detection areas, the area with insufficient fluidity can be identified. By establishing a mapping relationship between pressure and temperature requirements, the heating element 31 can perform additional heating on the area with insufficient fluidity, softening the degradable plastic in the area with insufficient fluidity, thereby reducing its viscosity, making it flow more uniformly, better filling the cavity with thin walls or complex structures, avoiding defects such as short shots and sink marks, improving the appearance quality and mechanical properties of the product, and reducing the scrap rate.

[0075] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow, in general, the principles of the present disclosure and include other known or customary features not specifically mentioned herein. The specification and examples are to be regarded as illustrative only, and the true scope and spirit of the present disclosure are indicated by the following claims.

[0076] It should be understood that the present disclosure is not limited to the precise structures described above and illustrated in the drawings and that various modifications and changes can be made without departing from the scope thereof. The scope of the present disclosure is limited only by the claims that follow.

Claims

1. A biodegradable plastic injection molding machine, characterized in that, include: The injection molding machine base (1) has a dustproof cover (11) on its upper part. The mold assembly (2) is located in the enclosed space formed by the injection molding machine base (1) and the dust cover (11). The mold assembly (2) includes a fixed injection mold (21) and a moving injection mold (22). The fixed injection mold (21) is relatively stationary with the injection molding machine base (1). The moving injection mold (22) can move on the injection molding machine base (1). The fixed injection mold (21) and the moving injection mold (22) can cooperate to form an injection cavity for accommodating biodegradable plastic. The injection extruder (3) has multiple heating elements (31) distributed along the direction of biodegradable plastic injection on the side wall of its injection channel. Injection flowability monitoring component (4), which is used to obtain temperature and pressure values ​​at different locations in the injection channel along the injection direction of the biodegradable plastic; The injection flow monitoring component (4) includes a detection array evenly distributed on the injection channel, and each detection array includes at least one temperature detection element (41) and at least one pressure detection element (42). The injection molding machine is configured to perform the following control processes: The detection combinations at different locations are sorted into regions along the injection path, and the injection channel is divided into different detection regions; In the standby state of the injection extruder, the average value of the detected temperature by the temperature detection element in the detection area is calculated. If the average value of the detected temperature is lower than the preset standard, the heating element is controlled to perform heat output. In the output state of the injection molding extruder, the average value of the pressure detection element and the average value of the temperature detection element in the detection area are calculated, and the heating element is controlled to change the heat output power according to the difference between the average pressures in different detection areas. The step of calculating the average value of the pressure detection element and the average value of the temperature detection element within the detection area under the output state of the injection molding extruder, and controlling the heating element to change the heat output power according to the difference between the average pressures in different detection areas, includes: Calculate the pressure difference between the average pressure of adjacent detection areas, and mark the areas with pressure differences exceeding the average value as areas with insufficient flow. The excess pressure in the area of ​​insufficient flowability is converted into the thermal compensation power required for that area, and this thermal compensation power is transferred to the biodegradable plastic through the heating element.

2. The biodegradable plastic injection molding machine according to claim 1, characterized in that: The injection channel of the injection extruder (3) passes through the injection mold (21) and is connected to the injection cavity. The part of the injection channel located inside the injection cavity is equipped with an injection nozzle (32).

3. The biodegradable plastic injection molding machine according to claim 1, characterized in that: A mold-closing cylinder (221) is provided on one side of the injection molding moving mold (22) and is fixed to the injection molding machine base (1). The mold-closing cylinder (221) drives the injection molding moving mold (22) to adjust the distance between it and the injection molding fixed mold (21) through the telescopic bracket (222). A demolding cylinder (223) is fixed on the side of the injection molding moving mold (22) away from the injection molding fixed mold (21). The output end of the demolding cylinder (223) is fixed with a top mold bracket (224) that can extend into the injection cavity.

4. The biodegradable plastic injection molding machine according to claim 1, characterized in that: The screw in the injection channel of the injection extruder (3) is divided into a feeding section, a compression section and a metering section. The length-to-diameter ratio of the feeding section is 2.5 and the screw groove depth is 0.25d. The length-to-diameter ratio of the compression end is 5 and the screw groove depth gradually decreases from 0.25d to 0.15d. The length-to-diameter ratio of the metering section is 4 and the screw groove depth is 0.15d.

5. A biodegradable plastic injection molding machine according to claim 1, characterized in that: The basic output power of the heating element (31) decreases sequentially along the injection direction of the biodegradable plastic, and the heating temperature range of the heating element (31) is 160-190℃.

6. An injection molding method using a biodegradable plastic injection molding machine as described in any one of claims 1-5, characterized in that, Includes the following steps: S100: The detection combinations at different locations are sorted into regions along the injection path, and the injection channel is divided into different detection regions; S200: In the standby state of the injection extruder, calculate the average value of the temperature detected by the temperature detection element in the detection area. If the average value of the detected temperature is lower than the preset standard, control the heating element to perform heat output. S300: In the output state of the injection molding extruder, calculate the average value of the pressure detection element and the average value of the temperature detection element in the detection area, and control the heating element to change the heat output power according to the difference between the average pressures in different detection areas. Step S300 includes: S301: Calculate the pressure difference between the average pressure of adjacent detection areas, and mark the areas where the pressure difference exceeds the average value as areas with insufficient flow. S302: Converts the excess pressure in the insufficient flow area into the heat compensation power required for that area, and transfers that heat compensation power to the biodegradable plastic through a heating element.

7. The injection molding method according to claim 6, characterized in that, The formula for converting the pressure excess in the insufficient flow area into the required heat compensation power for that area in step S302 is as follows: Where F is the actual output power; A is the basic output power; k is the thermal compensation coefficient; P is the pressure excess in the region with insufficient fluidity; V is the volume of the region with insufficient fluidity; and t is the heating time.

8. The injection molding method according to claim 6, characterized in that, In step S200, if the average value of the detected temperature is lower than the preset standard, the formula for controlling the heating element to perform heat output is as follows: Where N is the actual output power; S is the basic output power; M is the temperature compensation coefficient; and L is the difference between the preset standard temperature and the average temperature of the detection area.

Images