WO2021031120A1 - Device and method for preventing vacuum material returning in an extruder - Google Patents

Abstract

Disclosed are a device and method for preventing vacuum material returning in an extruder. The device comprises an extruder barrel, a vacuum cavity assembly, a vacuumizing assembly and a safety valve. The safety valve comprises a valve sleeve assembly, a valve element assembly and a thermal induction execution component, and the thermal induction execution component is configured to act to push the valve element assembly to open a valve path after the thermal induction execution component is heated to a phase change temperature under the action of heat of molten materials in the vacuum cavity assembly when the molten materials approach the thermal induction execution component. By means of a simple mechanical device, vacuum material is effectively prevented from returning, a sound alarm can be further given in a timely manner to alert workers to perform process adjustment and cleaning, and the product quality and the production efficiency are improved. No optics, circuits or sensors are used, the function thereof is reliable, the cost is low, modification can be directly made to an existing apparatus, the modification amount is small, operation is stable, and the product quality is stable and reliable.

Description

Device and method for preventing vacuum return of extruder Technical field

The invention relates to the technical field of polymer material processing, in particular to a device and method for preventing vacuum return of an extruder.

Background technique

During the processing of polymer materials, especially in the production process of plastic extrusion and granulation, the water vapor, small molecular substances, degraded substances and volatiles in the materials will produce low boiling substances and low boiling substances at higher processing temperatures. Residues in the product will affect the mechanical properties, thermal properties, aging resistance, color and appearance of the material. In order to make the equipment operate normally and to ensure that the product meets the requirements, low boiling substances need to be extracted. If the low-boiling material cannot be drawn out in time, it will cause the low-boiling material to accumulate in the vacuum gland. If it is not cleaned for a long time, it will cause broken bars and even seriously affect the product quality.

In the prior art, the low-boiling matter in the melt is usually extracted in time through a negative pressure device. During the extrusion production process, due to various factors, the phenomenon of melt accumulation and overflow at the vacuum exhaust port is called vacuum return, also called vacuum feed, vacuum return, etc. After the vacuum return material overflows, it accumulates in a closed vacuum chamber and cannot be observed and eliminated in time. In severe cases, it even enters the negative pressure pipeline. After solidification, the pipeline is blocked so that the vacuuming effect cannot be exerted. The low-boiling matter condenses into the liquid in the vacuum chamber and the pipeline, and it stays in the vacuum chamber for a long time and turns yellow, black or even The carbonized materials will flow down into the extruder and be gradually brought into the product, causing quality problems such as product discoloration and black spots, resulting in significant production losses. In the prior art, processing and production are usually continued after shutting down and cleaning regularly or according to product abnormalities. This conventional operation has the following shortcomings: the vacuum return material can not be found in time, which will bring hidden product quality hazards, such as black spot defects when producing white materials; serious return material will cause strips to be broken, and shutdown cleaning increases the labor intensity of employees and reduces work efficiency , Increase the cost of product manufacturing.

In this regard, there has been an improved method of designing a vacuum device with an observation window and a vacuum chamber with a structure to prevent backflow of materials. However, the improvement of the existing vacuum chamber structure design does not have a good technical effect. Low boiling substances will condense on the observation window and affect the normal observation of workers. In the production process, the instrument indication of the negative pressure device is often used to judge whether the vacuum is working normally. In fact, the instrument indication is still normal after the vacuum is blocked, but it does not work. It is difficult to find problems in time and take corrective measures during production. There are also some methods that use optical detection of materials to detect and alarm the vacuum port accumulation, but the high temperature of the vacuum port, high oil smoke, dust, frequent disassembly and equipment vibration, etc., affect the accuracy of the detection device, and the on-site environment for the detection of optical components , Lines, etc. have a greater impact, and even damage the detection and alarm device. In summary, there is currently no better technical equipment to comprehensively solve such problems.

Summary of the invention

In order to overcome the shortcomings of the prior art, the present invention provides a device and method for preventing the vacuum return of the extruder. The specific technical solutions are as follows:

A device for preventing vacuum return of an extruder includes an extruder barrel, a vacuum cavity assembly, a vacuuming assembly and a safety valve. The vacuum cavity assembly is connected to the extruder barrel, and the vacuuming The component communicates with the vacuum chamber component;

The safety valve includes a valve sleeve assembly, a valve core assembly, and a heat-sensitive actuator. The valve core assembly and the heat-sensitive actuator are installed in the valve sleeve assembly, and the valve sleeve assembly extends into the vacuum chamber from the outside. Body assembly, the valve sleeve assembly has a valve circuit communicating the inside and the outside of the vacuum chamber assembly, the valve core assembly is configured to make the valve circuit in a normally closed state, and the thermal induction actuator is configured to When there is a molten material in the vacuum chamber assembly close to the heat-sensitive actuator, under the action of the heat of the molten material, the heat-sensitive actuator heats up to the phase change temperature and generates an action to push the valve core assembly to open. The valve path.

In a specific embodiment, the heat-sensitive actuator includes a shape memory spring, one end of the shape memory spring acts on the valve core assembly, and the other end of the shape memory spring acts on the valve sleeve assembly.

In a specific embodiment, the safety valve further includes a locking spring configured to compress the valve core assembly, and the direction of the force of the locking spring on the valve core assembly is the same as The direction of the force of the shape memory spring on the valve core assembly is opposite, and the force of the locking spring on the valve core assembly is greater than the effect of the shape memory spring on the valve core assembly before the phase change But less than the force of the shape memory spring on the valve core assembly after the phase change.

In a specific embodiment, the valve core assembly includes a valve stem and a sealing head located on the valve stem, the valve stem is inserted in the valve path, and the valve sleeve assembly is in the valve path. There is a sealing step, and the sealing head cooperates with the sealing step to close or open the valve path.

In a specific embodiment, the locking spring and the shape memory spring exert a force on the valve core assembly from the same end of the valve core assembly;

Preferably, one end of the locking spring is connected to the valve core assembly, and the other end is connected to the shape memory spring.

In a specific embodiment, the shape memory spring is provided at one end of the valve core assembly located in the vacuum chamber assembly, and the locking spring is provided at the other end of the valve core assembly.

In a specific embodiment, the safety valve further includes an airflow sounding device configured to emit an alarm sound driven by the airflow when the valve path is opened;

Preferably, the airflow sounding device includes an airflow inlet, a sounding cavity, and an airflow outlet, the airflow inlet communicates with the atmosphere, and the airflow outlet communicates with the valve path.

In a specific embodiment, the valve sleeve assembly includes an upper valve cover, a valve sleeve body, and a lower valve cover. The upper valve cover and the lower valve cover are respectively detachably sleeved on the valve sleeve body. At both ends, the valve sleeve body is detachably fixed at the opening of the vacuum chamber assembly, the lower valve cover is located in the vacuum chamber assembly, and the valve path communicates with the lower valve cover. The vacuum chamber assembly;

The other end of the shape memory spring is connected to the inner wall of the lower valve cover, and the airflow sounding device is arranged in the upper valve cover.

In a specific embodiment, the upper valve cover and the valve sleeve body are fastened and connected by threads, the lower valve cover and the valve sleeve body are fastened by threads, and the lower valve cover and the A lock nut is arranged at the joint of the valve sleeve body.

In a specific embodiment, the lower valve cover is made of a thermally conductive material;

Preferably, the lower valve cover adopts copper sheet material when the molten material is a polyolefin system;

Preferably, the lower valve cover is made of stainless steel when the molten material is a nylon system.

In a specific embodiment, the side circumferential surface of the lower valve cover is provided with a through hole configured to communicate the valve path and the vacuum chamber assembly; preferably, the through hole extends downwardly from the inside to the outside.

In a specific embodiment, the phase transition temperature of the thermal induction actuator is 60°C to 180°C; preferably, it is 70°C to 140°C.

In a specific embodiment, the vacuum chamber assembly includes a capping device and a vacuum chamber, the vacuum cap is installed at the opening of the extruder barrel, and the vacuum chamber is connected to the vacuum cap A channel connecting the opening of the extruder barrel and the vacuum chamber is opened in the vacuum gland.

A method for preventing vacuum return of extruder, using the device for preventing vacuum return of extruder described in any of the foregoing technical solutions to perform the following operations:

The phase transition temperature of the thermal induction actuator is preset according to the composition of the molten material. When a vacuum return occurs, the molten material overflows into the vacuum chamber assembly, and the molten material approaches the thermal induction actuator. Make the temperature of the heat-sensitive actuator exceed the phase transition temperature, the heat-sensitive actuator generates an action after the phase change to push the valve core assembly to open the valve path, and the external airflow enters the vacuum chamber through the valve path The component realizes that the pressure difference between the negative pressure component and the extruder barrel is reduced when the vacuum is returned, and the extraction of low-boiling substances is stopped, and the aggravation of the vacuum return is suppressed. At the same time, the airflow sound device makes a sound, To remind the operator.

The present invention has at least the following beneficial effects:

According to the device and method for preventing vacuum return of extruder provided by the present invention, when vacuum return occurs, the molten material overflows into the vacuum chamber assembly, and the molten material approaches the heat-sensing actuator, causing the The temperature of the thermal sensing actuator exceeds the phase transition temperature. After the phase transition, the thermal sensing actuator generates an action to push the valve core assembly to open the valve path, and the external airflow enters the vacuum chamber assembly through the valve path to achieve When the vacuum is returned, the pressure difference between the negative pressure component and the extruder barrel is reduced, and the extraction of low-boiling substances is stopped, and the aggravation of the vacuum return is suppressed. Further, the air flow sound device emits a sound to remind the operator.

Therefore, the present invention effectively prevents the occurrence of vacuum return and prompts the staff to perform process adjustment and cleaning through simple mechanical devices, thereby improving product quality and production efficiency. The device has a simple structure, does not use optics, circuits and sensors, has reliable functions and low cost, and solves the problems existing in the prior art.

Moreover, the device has a simple structure, can be directly modified on the existing device, has a small amount of modification, stable operation, stable and reliable product quality, and solves the problems in the prior art.

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, preferred embodiments are described below in detail with accompanying drawings.

Description of the drawings

In order to explain the technical solutions of the embodiments of the present invention more clearly, the following will briefly introduce the drawings that need to be used in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore do not It should be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative work.

Figure 1 is a cross-sectional view of the normal production of the device for preventing vacuum return of the extruder in Example 1;

2 is a cross-sectional view of the device for preventing the vacuum return of the extruder in Example 1 when the vacuum is returned;

3 is a schematic diagram of the safety valve passage closed in Embodiment 1;

4 is a schematic diagram of the opening of the safety valve passage in Embodiment 1;

5 is a schematic diagram of the safety valve passage closed in Embodiment 2;

Fig. 6 is a schematic diagram of the opening of the safety valve passage in the second embodiment.

Symbol description of main components:

1- Extruder barrel; 2- Extrusion screw; 3- Molten material; 4- Flange; 5- Vacuum gland; 6-Vacuum chamber; 7- Vacuum interface tube; 8- Seal gland; 9- Safety Valve; 901,901'-valve sleeve body; 902,902'-seal ring; 903,903'-valve stem; 904,906'-locking spring; 905,904'-upper valve cover; 906,909,907 '- lock nut; 907, 905'- airflow sound device; 908, 908'- adapter; 910, 910'- shape memory spring; 911, 909'- lower valve cover; 9111, 9091'- through hole.

detailed description

Example 1

As shown in Figure 1 and Figure 2, this embodiment provides a device for preventing vacuum return of the extruder, which includes an extruder barrel 1, a vacuum chamber assembly, a vacuuming assembly and a safety valve 9. The vacuum chamber The component is connected to the extruder barrel 1, and the vacuuming component is connected to the vacuum chamber component.

Wherein, the extruder barrel 1 is provided with an extrusion assembly configured to convey the molten material 3, such as an extrusion screw 2. The upper part of the rear part of the extruder barrel 1 (close to the extruder head) has an opening communicating with the vacuum chamber assembly, the material in this area is completely melted, and the vacuum chamber assembly is installed at the opening. Those skilled in the art can understand that in order to convey materials in the extruder barrel 1, the extruder barrel also has a heating element, and these parts of the extruder body are not described in this embodiment.

As shown in Figure 1, the vacuum chamber assembly includes a capping device and a vacuum chamber 6. The vacuum cap 5 is installed at the opening of the extruder barrel 1. The vacuum chamber 6 is connected to the vacuum cap 5, and the vacuum cap 5 is opened There is a passage connecting the opening of the extruder barrel 1 and the vacuum chamber 6. Specifically, the vacuum gland 5 is connected to the extruder barrel 1 through the flange 4 at the opening of the extruder barrel 1. In this embodiment, the gland of the vacuum chamber 6 has a specific shape, for example, the cross section of the channel has a narrow bottom and a wide top, similar to an inverted cone structure. The vacuum assembly includes a negative pressure generating device and a vacuum interface tube 7. The vacuum interface tube 7 communicates with the vacuum chamber 6, and the vacuum interface tube 7 is connected to the negative pressure generating device. The vacuum chamber 6 includes an integrally formed shell or a split shell. When it is a split shell, the vacuum chamber 6 includes a lower shell and a sealing gland 8 located on the top of the lower shell. The vacuum chamber assembly has an opening. Preferably, the opening of the vacuum chamber assembly is located at the top, for example, on the sealing gland 8.

In this embodiment, the safety valve 9 includes a valve sleeve assembly, a valve core assembly and a heat-sensitive actuator. Among them, the valve core assembly and the thermal sensing actuator are installed in the valve sleeve assembly, the valve sleeve assembly extends into the vacuum chamber assembly from the outside, and the valve sleeve assembly has a valve path connecting the inside and outside of the vacuum chamber assembly. The valve core assembly It is configured to make the valve circuit in a normally closed state, and the thermal induction actuator is configured to heat the molten material 3 (such as heat radiation or heat transfer) when the molten material 3 is close to the thermal induction actuator in the vacuum chamber assembly After the induction actuator heats up to the phase change temperature, it produces an action to push the spool assembly to open the valve circuit.

Specifically, as shown in FIGS. 1-4, the thermally sensitive actuator includes a shape memory spring 910, such as a spring supported by a shape memory alloy. When the temperature does not reach the phase transition temperature, the shape memory spring 910 has better compressibility. When the temperature reaches the phase transition temperature, the shape memory spring 910 instantly returns to the memory state and exhibits super elasticity. One end of the shape memory spring 910 acts on the valve core assembly, and the other end of the shape memory spring 910 acts on the valve sleeve assembly.

In this embodiment, the safety valve 9 further includes a locking spring 904 configured to compress the valve core assembly. The direction of the force of the locking spring 904 on the valve core assembly is the same as that of the shape memory spring 910 on the valve core assembly. The direction of the force is opposite, and the force of the locking spring 904 on the valve core assembly is greater than the force of the shape memory spring 910 on the valve core assembly before the phase change, but less than the effect of the shape memory spring 910 on the valve core assembly after the phase change force.

Illustratively, the valve sleeve assembly includes an upper valve cover 905, a valve sleeve body 901, and a lower valve cover 911. The upper valve cover 905 and the lower valve cover 911 are respectively detachably sleeved on both ends of the valve sleeve body 901.

As a preferred detachable connection structure of the upper valve cover 905 and the lower valve cover 911, the upper valve cover 905 and the valve sleeve body 901 are fastened by threads, and the lower valve cover 911 and the valve sleeve body 901 are fastened by threads. A lock nut 909 is provided at the joint of the lower valve cover 911 and the valve sleeve body 901. Preferably, a lock nut 906 is also provided at the joint of the upper valve cover 905 and the valve sleeve body 901. Since the upper valve cover 905, the valve sleeve body 901, and the lower valve cover 911 are fastened by threads, the positions can be adjusted so that the overall length of the valve sleeve assembly can be adjusted, which facilitates adjustment of the compression force of the shape memory spring 910 and the locking spring 904. The lock nut can adjust the positions of the upper valve cover 905 and the lower valve cover 911 so that the restoring force of the adjusting spring is appropriate and then fixed, which has the effect of preventing vibration and loosening.

The valve sleeve body 901 is detachably fixed at the opening of the vacuum chamber assembly, the lower valve cover 911 is located in the vacuum chamber assembly, and the valve path is connected to the vacuum chamber assembly at the lower valve cover 911. Preferably, the valve sleeve body 901 is connected to the vacuum gland 5, and there is a sealing ring 902 between the connecting surfaces.

It should be noted that in this embodiment, the valve sleeve assembly including the upper valve cover 905, the valve sleeve body 901 and the lower valve cover 911 is only a preferred structure of the valve sleeve assembly. In addition to the preferred structure, it can also have other structures. Structural form, for example, the valve sleeve assembly is a one-piece structure, a two-stage structure or other structural forms. In addition, the lower valve cover 911 and related structures have different length designs according to the height of the vacuum chamber 6 and the type of material.

In this embodiment, the valve core assembly includes a valve stem 903 and a sealing head located on the valve stem 903. The valve stem 903 passes through the valve path. The valve sleeve assembly has a sealing step on the valve path. The sealing head cooperates with the sealing step to close Or open the valve circuit. Wherein, the sealing step divides the valve path into two upper and lower hollow structures, and these two hollow structures can be used to place the shape memory spring 910 and the locking spring 904. Wherein, the sealing head is arranged in the middle or upper part of the valve stem 903, and an integrally formed structure is preferred between the two. Preferably, the mating surface between the sealing head and the sealing step is a tapered surface, that is, a tapered surface seal is formed between the two.

In this embodiment, the shape memory spring 910 is provided at one end of the valve core assembly located in the vacuum chamber assembly, and the locking spring 904 is provided at the other end of the valve core assembly.

Based on the description of the foregoing part of this embodiment, a more specific installation structure can be obtained. As shown in Figure 3, the shape memory spring 910 is located in the hollow structure below the sealing step in the valve circuit, and the locking spring 904 is located in the sealing step in the valve circuit. Inside the hollow structure above. One end of the shape memory spring 910 directly acts on the valve stem 903 or an adapter 908 (such as a screw or a plate) on the valve stem 903, and the other end of the shape memory spring 910 acts on the inner wall of the end of the lower valve cover 911. One end of the locking spring 904 acts on the inner wall of the end of the upper valve cover 905, and the other end of the locking spring 904 acts directly on the valve stem 903 or acts on the valve stem 903 through an adapter 908 (such as a screw or a plate), Or the other end of the locking spring 904 abuts on the sealing head.

In this embodiment, the safety valve 9 further includes an air flow sounding device 907, which is configured to emit an alarm sound driven by the air flow when the valve path is opened. Preferably, the airflow sounding device 907 is provided in the upper valve cover 905.

As a preferred airflow sounding device 907, the airflow sounding device 907 includes an airflow inlet, a sounding cavity, and an airflow outlet. The airflow inlet is in communication with the atmosphere, and the airflow outlet is in communication with the valve path. When air flows through the sound cavity, the sound cavity makes a sound. Preferably, the vocal cavity is a whistle-like structure.

In this embodiment, the lower valve cover 911 is made of a thermally conductive material, which is commonly used copper, aluminum, iron, and alloys thereof. In addition, the lower valve cover 911 is made of copper sheet when the molten material 3 is a polyolefin system, and is made of stainless steel when the molten material 3 is a nylon system.

In this embodiment, a through hole 9011 is opened on the circumferential surface of the lower valve cover 911, which is configured to communicate the valve path and the vacuum chamber assembly. Preferably, the through hole 9011 obliquely extends downward from the inside to the outside.

In this embodiment, the phase transition temperature of the shape memory spring 910 is 60°C to 180°C. Preferably, it is 70°C to 140°C.

A method for preventing vacuum return of extruder, using the device for preventing vacuum return of extruder of any of the foregoing technical solutions to perform the following operations:

Pre-set the phase transition temperature of the thermal induction actuator according to the composition of the molten material 3. When the vacuum return occurs, the molten material 3 overflows into the vacuum chamber assembly, and the molten material 3 approaches the thermal induction actuator to cause heat induction The temperature of the actuator exceeds the phase transition temperature. After the phase transition of the heat-sensing actuator, the action is generated to push the valve core assembly to open the valve path, and the external airflow enters the vacuum chamber assembly through the valve path to realize the negative pressure assembly and extruder when the vacuum is returned. The pressure difference in the passage of the barrel 1 is reduced, and the extraction of low boiling substances is stopped to suppress the aggravation of the vacuum return. At the same time, the airflow sound device 907 makes a sound to remind the operator to perform process adjustment or cleaning.

Specifically, as shown in Figure 1, during normal production, the molten material 3 is mainly in the lower part of the gland of the vacuum chamber 6. The air temperature in the vacuum chamber 6 is mainly the heat transferred from the extruder barrel 1 and the hot air, which is lower than safe The phase change temperature of the shape memory spring 910 at the lower part of the valve 9. As shown in Fig. 3, the locking spring 904 in the valve cover 905 on the safety valve 9 compresses the shape memory spring 910 through the valve stem 903 and the adapter 908, and the sealing head on the valve stem 903 and the valve sleeve body 901 seal the steps Press tightly to close the valve circuit, the vacuum chamber 6 does not communicate with the external environment, and the negative pressure component maintains the vacuum degree of the low boiling substances in the extracted material, so that the low boiling substances in the molten material 3 are continuously drawn out, realizing stable production of products.

As shown in Figure 2, when a vacuum return occurs, the molten material 3 overflows into the vacuum chamber 6, and the molten high-temperature material is closer to the lower valve cover 911 under the safety valve 9, making the lower valve cover 911 and its internal The temperature of the shape memory spring 910 increases. As shown in Figure 4, the temperature of the shape memory spring 910 exceeds its phase transition temperature, and instantly exhibits strong elasticity and returns to the memory state. The restoring force higher than the compression force of the upper locking spring 904 of the safety valve 9 is transmitted through the adapter 908 Give the valve stem 903, compress the upper locking spring 904, so that the sealing head on the valve stem 903 is separated from the sealing step in the valve sleeve body 901, and the valve path is opened. The external airflow enters the valve path through the structure of the airflow sounding device 907 on the top of the upper valve cover 905, the air passes through the through hole on the adapter 908 and blows down toward the molten material 3 through the through hole 9111 placed in the lower valve cover 911. Furthermore, the external air enters the vacuum chamber 6 to reduce the pressure difference between the negative pressure component and the extruder barrel 1 during material return, and stop the extraction of low-boiling substances in the molten material 3 through the vacuum chamber 6 to suppress the vacuum return At the same time, the airflow sound device 907 emits a continuous sound to remind the operator to adjust or clean the process.

Therefore, the present embodiment effectively prevents the occurrence of vacuum return and prompts the staff to make process adjustments and cleanings through simple mechanical devices, thereby improving product quality and production efficiency. The device has a simple structure, does not use optics, circuits and sensors, has reliable functions and low cost, and solves the problems existing in the prior art.

Example 2

Compared with embodiment 1, the main difference of this embodiment is:

In this embodiment, the locking spring 906' and the shape memory spring 910' apply force to the valve core assembly from the same end of the valve core assembly. Specifically, the locking spring 906 ′ and the shape memory spring 910 ′ are both in the lower part of the safety valve 9.

Preferably, one end of the locking spring 906' is connected to the valve core assembly, and the other end is connected to the shape memory spring 910'.

As shown in Figure 5, during normal production, the temperature of the lower valve cover 909' is relatively low, and the internal shape memory spring 910' is very easy to be compressed and deformed, and the locking spring 906' stretches the adapter 908' downward The shape memory spring 910' in the lower valve cover 909' is compressed by the downward force of the adapter 908', and the adapter 908' transmits the downward force to the valve stem 903' and to the valve stem 903' The sealing head of the valve is closely matched with the sealing step of the valve sleeve body 901' to close the safety valve passage. At this time, the vacuum chamber 6 is not in communication with the external environment, and the negative pressure component maintains the vacuum degree for extracting low-boiling substances in the molten material, so that the low-boiling substances in the molten material are continuously extracted, and stable production of products is realized. The lock nut 907' can be fixed after adjusting the position of the lower valve cover 909' so that the spring's restoring force is appropriate, which can prevent vibration and loosening. The adapter 908' is preferably an adjusting nut threadedly connected to the valve stem, which can adjust the stroke and state of the locking spring 906' and the shape memory spring 910' to ensure the normal operation of the safety valve.

As shown in Figure 6, when a vacuum return occurs, the molten material overflows into the vacuum chamber 6, and the molten high-temperature material is closer to the lower valve cover 909' under the safety valve 9, making the lower valve cover 909' and its interior The temperature of the shape memory spring 910' rises, the temperature of the shape memory spring 910' exceeds its phase transition temperature, the restoring force of the shape memory spring 910' is higher than the compression force of the locking spring 906', and the shape memory spring 910' performs instantly The strong elasticity is released and the memory is restored, and the locking spring 906' is compressed upward through the adapter 908'. At the same time, the valve stem 903' moves upward, so that the mating surface between the sealing head on the valve stem 903' and the sealing step of the valve sleeve body 901' is separated, and the valve path is opened. The external air enters the valve sleeve body 901' through the structure of the upper valve cover 904' and the top airflow sounding device 905', and the through hole 9091' of the lower gas lower valve cover 909' blows down to the molten material, and then the external air enters the vacuum chamber 6 to achieve When the vacuum is returned to the material, the pressure difference between the negative pressure component and the extruder barrel is reduced, and the low-boiling material in the molten material through the vacuum chamber 6 is stopped to suppress the aggravation of the vacuum return. At the same time, the airflow sound device 905' emits continuous The sound reminds the operator to adjust or clean up the process.

The other features in this embodiment are the same as those in Embodiment 1, and will not be repeated here.

As those skilled in the art can understand, the drawings are only schematic diagrams of preferred implementation scenarios, and the modules or processes in the drawings are not necessarily necessary for implementing the present invention.

Those skilled in the art can understand that the modules in the device in the implementation scenario can be distributed in the device in the implementation scenario according to the description of the implementation scenario, or can be changed to be located in one or more devices different from the implementation scenario. The modules of the above implementation scenarios can be combined into one module or further divided into multiple sub-modules.

The above-mentioned serial number of the present invention is only for description, and does not represent the pros and cons of implementation scenarios.

What has been disclosed above are only a few specific implementation scenarios of the present invention, but the present invention is not limited thereto, and any changes that can be thought of by those skilled in the art should fall into the protection scope of the present invention.

Claims (19)

A device for preventing vacuum return of an extruder, which is characterized in that it comprises an extruder barrel, a vacuum cavity assembly, a vacuuming assembly and a safety valve, the vacuum cavity assembly is connected to the extruder barrel, The vacuum assembly is connected to the vacuum cavity assembly; The safety valve includes a valve sleeve assembly, a valve core assembly, and a heat-sensitive actuator. The valve core assembly and the heat-sensitive actuator are installed in the valve sleeve assembly, and the valve sleeve assembly extends into the vacuum chamber from the outside. Body assembly, the valve sleeve assembly has a valve circuit communicating the inside and the outside of the vacuum chamber assembly, the valve core assembly is configured to make the valve circuit in a normally closed state, and the thermal induction actuator is configured to When there is a molten material in the vacuum chamber assembly close to the heat-sensitive actuator, under the action of the heat of the molten material, the heat-sensitive actuator heats up to the phase change temperature and generates an action to push the valve core assembly to open. The valve path. The device for preventing vacuum return of extruder according to claim 1, wherein the heat-sensitive actuator comprises a shape memory spring, one end of the shape memory spring acts on the valve core assembly, and the shape The other end of the memory spring acts on the valve sleeve assembly. The device for preventing vacuum return of extruder according to claim 2, wherein the safety valve further comprises a locking spring configured to compress the valve core assembly, and the locking The direction of the force of the spring on the valve core assembly is opposite to the direction of the force of the shape memory spring on the valve core assembly, and the force of the locking spring on the valve core assembly is greater than that of the shape memory The force of the spring on the valve core assembly before the phase change is smaller than the force of the shape memory spring on the valve core assembly after the phase change. The device for preventing vacuum return of extruder according to claim 3, wherein the valve core assembly includes a valve stem and a sealing head on the valve stem, and the valve stem penetrates the valve stem. In the circuit, the valve sleeve assembly has a sealing step on the valve circuit, and the sealing head cooperates with the sealing step to close or open the valve circuit. The device for preventing vacuum return of extruder according to claim 3, characterized in that the locking spring and the shape memory spring exert a force on the valve core assembly from the same end of the valve core assembly. The device for preventing vacuum return of the extruder according to claim 3, wherein one end of the locking spring is connected to the valve core assembly, and the other end is connected to the shape memory spring. The device for preventing vacuum return of extruder according to claim 3, characterized in that the shape memory spring is arranged at one end of the valve core assembly located in the vacuum chamber assembly, and the locking spring Set at the other end of the valve core assembly. The device for preventing vacuum return of extruder according to claim 1, wherein the safety valve further comprises an airflow sounding device, and the airflow sounding device is configured to be driven by the airflow when the valve path is opened. The alarm sounds. The device for preventing vacuum return of extruder according to claim 8, characterized in that the airflow sounding device comprises an airflow inlet, a sounding cavity, and an airflow outlet, the airflow inlet being in communication with the atmospheric environment, and the airflow outlet It communicates with the valve circuit. The device for preventing vacuum return of extruder according to claim 8, wherein the valve sleeve assembly includes an upper valve cover, a valve sleeve body and a lower valve cover, the upper valve cover and the lower valve cover Are respectively detachably sleeved on both ends of the valve sleeve body, the valve sleeve body is detachably fixed at the opening of the vacuum chamber assembly, and the lower valve cover is located in the vacuum chamber assembly, The valve path communicates with the vacuum chamber assembly at the lower valve cover; The other end of the shape memory spring is connected to the inner wall of the lower valve cover, and the airflow sounding device is arranged in the upper valve cover. The device for preventing vacuum return of extruder according to claim 10, characterized in that, the upper valve cover and the valve sleeve body are fastened and connected by threads, and the lower valve cover and the valve sleeve body pass through The connection is screwed tightly, and a lock nut is arranged at the connection between the lower valve cover and the valve sleeve body. The device for preventing vacuum return of extruder according to claim 10, wherein the lower valve cover is made of a thermally conductive material. The device for preventing vacuum return of extruder according to claim 12, wherein the lower valve cover is made of copper sheet when the molten material is a polyolefin system. The device for preventing vacuum return of the extruder according to claim 12, wherein the lower valve cover is made of stainless steel when the molten material is a nylon system. The device for preventing vacuum return of extruder according to claim 10, characterized in that the side circumferential surface of the lower valve cover is provided with a through hole configured to communicate the valve path and the vacuum chamber assembly; preferably Ground, the through hole extends obliquely downward from the inside to the outside. The device for preventing vacuum return of extruder according to claim 1, characterized in that the phase transition temperature of the thermal induction actuator is 60°C to 180°C. The device for preventing vacuum return of the extruder according to claim 1, wherein the phase transition temperature of the thermal induction actuator is 70°C to 140°C. The device for preventing vacuum return of extruder according to claim 1, wherein the vacuum chamber assembly includes a capping device and a vacuum chamber, and the vacuum cap is installed on the extruder barrel. At the opening, the vacuum chamber is connected to the vacuum gland, and a channel connecting the opening of the extruder barrel and the vacuum chamber is opened in the vacuum gland. A method for preventing vacuum return of an extruder, characterized in that the device for preventing vacuum return of an extruder according to any one of claims 1-18 is used to perform the following operations: The phase transition temperature of the thermal induction actuator is preset according to the composition of the molten material. When a vacuum return occurs, the molten material overflows into the vacuum chamber assembly, and the molten material approaches the thermal induction actuator. Make the temperature of the heat-sensitive actuator exceed the phase transition temperature, the heat-sensitive actuator generates an action after the phase change to push the valve core assembly to open the valve path, and the external airflow enters the vacuum chamber through the valve path The component realizes that the pressure difference between the negative pressure component and the extruder barrel is reduced when the vacuum is returned, and the extraction of low-boiling substances is stopped, and the aggravation of the vacuum return is suppressed. At the same time, the airflow sound device makes a sound To remind the operator.

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