A quick demoulding mechanism for blow moulding plastic drums

Abstract

The application relates to the technical field of plastic bucket blow molding, in particular to a quick demolding mechanism for plastic bucket blow molding, which comprises a base; a bottom plate is fixedly connected to the top end of the outer wall of the base through a group of supporting columns; a driving device is fixedly connected to the top end of the outer wall of the base; a threaded shaft is arranged at the output end of the driving device; a group of connecting plates are slidably connected to the inner side wall of the bottom plate; the threaded shaft is driven to rotate by the driving device, the rotation of the threaded shaft drives the threaded plate and the linkage block to move upwards, drives a group of connecting rods, connecting plates and arc-shaped side plates to uniformly move away in all directions, the plastic bucket after blow molding is separated from all lateral constraints at the demolding moment, the demolding process is more stable and gentle, the operation process of the demolding procedure is simplified, the time required for single demolding is shortened, the continuous production efficiency of the blow molding is effectively improved, the barrel body of the plastic bucket is not easy to scratch, the defect rate is reduced, and the product quality and the aesthetic degree are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of plastic bucket blow molding technology, specifically to a rapid demolding mechanism for plastic bucket blow molding. Background Technology

[0002] Blow molding of plastic buckets is a molding method for hollow plastic products. It uses compressed air to inflate a heated and softened plastic preform, making it adhere tightly to the mold cavity wall. After cooling and solidification, a hollow bucket-shaped product is obtained. The quick demolding mechanism for blow molding of plastic buckets is a device in the blow molding process that achieves efficient and non-destructive demolding, solving problems such as the plastic bucket sticking to the mold after molding and high demolding resistance.

[0003] In existing technologies, the quick demolding mechanism for blow molding of plastic buckets generally adopts a two-half split and ejection structure. When the two halves of the molded plastic bucket are opened for demolding, the molded plastic bucket is prone to sticking to one half of the mold. Moreover, because the contact area between the molded plastic bucket and one half of the mold is relatively large, it is necessary to use ejector rods or ejector plates to apply a large mechanical force to force it out. This not only easily scratches the body of the molded plastic bucket, causing defects in the molded plastic bucket, resulting in reduced product quality and aesthetics, but also makes the demolding process more troublesome and increases demolding time. Summary of the Invention

[0004] The purpose of this invention is to address the problem that the rapid demolding mechanism for blow molding of plastic buckets typically employs a two-part split and ejection structure. This structure causes the molded plastic bucket to easily adhere to one half of the mold during demolding, and because the contact area between the molded plastic bucket and one half of the mold is relatively large, requiring a large mechanical force from ejector pins or plates to forcefully eject it. This not only easily scratches the body of the molded plastic bucket, causing defects and reducing product quality and aesthetics, but also makes the demolding process cumbersome and increases demolding time. Therefore, this invention proposes a rapid demolding mechanism for blow molding of plastic buckets.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A rapid demolding mechanism for blow molding of plastic buckets includes a base; a base plate is fixedly connected to the top of the outer wall of the base via a set of support columns; a driving device is fixedly connected to the top of the outer wall of the base; the output end of the driving device is provided with a threaded shaft; a set of connecting plates is slidably connected to the inner side wall of the base plate; an arc-shaped side plate is fixedly connected to one side of the inner wall of each of the connecting plates; a threaded plate is threadedly connected to the outer side wall of the threaded shaft; a linkage block is fixedly connected to the top of the outer wall of the threaded plate; a connecting rod is fixedly connected to the bottom of the outer wall of each of the connecting plates, and one end of the outer wall of each connecting rod is slidably connected to the inner side wall of the linkage block.

[0007] In a preferred embodiment of the present invention, the base plate includes an annular plate and a top rod; the outer side wall of the top rod is slidably connected to the inner side wall of the annular plate; the top rod is located above the linkage block; the inner side wall of the linkage block is inclined; the base plate and a set of arc-shaped side plates form a blow molding space.

[0008] In a preferred embodiment of the present invention, the top rod includes a housing, a sliding plate, and rods; the outer side wall of the sliding plate is slidably connected to the inner side wall of the housing; the bottom ends of the outer walls of a group of rods are all fixedly connected to the top ends of the outer walls of the sliding plate; the outer side walls of a group of rods are all slidably and sealingly connected to the inner side wall of the housing; a connecting block is fixedly connected to one side of the outer wall of the sliding plate, and one end of the outer wall of the connecting block is fixedly connected to the bottom end of the outer wall of the base plate.

[0009] In a preferred embodiment of the present invention, a spring is fixedly connected to the bottom of the outer wall of the base plate; a square block is fixedly connected to the outer wall of the housing; the bottom of the outer wall of the spring is fixedly connected to the top of the outer wall of the square block; and a damper is provided at the spring.

[0010] In a preferred embodiment of the present invention, a set of electric push rods are fixedly connected to the top of the outer wall of the base by a set of fixing rods; a square plate is fixedly connected to one end of the outer wall of each set of electric push rods; a set of push rods is fixedly connected to one side of the outer wall of each set of square plates; and multiple sets of push rods are respectively located at the opening and closing points of a set of arc-shaped side plates.

[0011] In a preferred embodiment of the present invention, a thin-film pressure sensor is embedded on the inner wall surface of each of the arc-shaped side plates; an infrared temperature sensor is embedded at the top of the outer wall of the housing; a magnetic grating ruler is fixedly connected to one side of the outer wall of the threaded plate; a magnetic grating reading head that cooperates with the magnetic grating ruler is fixedly connected to the bottom of the outer wall of the base plate; the thin-film pressure sensor, the infrared temperature sensor and the magnetic grating reading head are all signal-connected to a controller; the controller is fixedly connected to the outer wall of the base.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] 1. The drive equipment rotates the threaded shaft, causing the threaded plate to move upward. This, in turn, causes the linkage block to move upward. As the linkage block moves upward, the inclined inner wall of the linkage block presses against a set of connecting rods, causing these rods to move outward. This movement of the connecting rods then moves the connecting plate, which slides against the inner wall of the base plate. This causes a set of curved side plates to evenly retract outward, allowing the blow-molded plastic bucket to be freed from all lateral constraints at the moment of demolding. This prevents the curved side plates from adhering to the bucket body, and also reduces the adhesion area, making the bucket less prone to scratches and lowering the defect rate. This ensures product quality and aesthetics. Furthermore, the even retraction design of the curved side plates makes the demolding process smoother and gentler, simplifying the demolding process and shortening the time required for a single demolding, effectively improving the continuous production efficiency of blow molding.

[0014] 2. As the curved side plate retracts outwards under the action of the linkage block, exposing the gap, the electric push rod starts simultaneously. The square plate pushes multiple sets of push rods to extend into the opening and closing gap of the curved side plate, effectively peeling away any burrs or localized welded areas of the plastic bucket that may be stuck to the side plate edge. This avoids localized stretching deformation of the bucket body caused by side plate edge adhesion during traditional demolding. After the curved side plate completes its retraction, the electric push rod drives the push rod to quickly return to its original position, preventing interference with the upward movement of the ejector rod. During the mold closing stage before blow molding, the electric push rod acts in the opposite direction on the curved side plate through the push rod, ensuring precise alignment of multiple curved side plates when closed, eliminating mold gaps, preventing flash from forming in the plastic melt during molding, further improving the molding accuracy of the plastic bucket, effectively reducing the defect rate in production. Furthermore, the electric push rod, driven by the push rod, can adjust the position of the plastic bucket, preventing it from shifting, tilting, or colliding, thus avoiding scratches. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a structural diagram of the main body of the present invention;

[0017] Figure 2 This is an exploded structural diagram of the arc-shaped side plate and the bottom plate of the present invention;

[0018] Figure 3 This is a structural diagram of the drive device, threaded plate, linkage block, and connecting rod of the present invention;

[0019] Figure 4 This is an exploded structural diagram of the annular plate and the top rod of the present invention;

[0020] Figure 5 This is an exploded structural diagram of the skateboard, rod, and housing of the present invention;

[0021] Figure 6 This is a structural diagram of the electric actuator, square plate, and push rod of the present invention;

[0022] Figure 7 This is a flowchart of the rapid demolding control method for blow molding of plastic buckets according to the present invention.

[0023] In the diagram: 1. Base; 2. Support column; 3. Base plate; 4. Drive device; 5. Threaded shaft; 16. Connecting plate; 17. Arc-shaped side plate; 6. Threaded plate; 7. Linkage block; 8. Connecting rod; 31. Ring plate; 32. Top rod; 321. Housing; 322. Slide plate; 323. Rod body; 9. Connecting block; 10. Spring; 11. Square block; 12. Fixed rod; 13. Electric push rod; 14. Square plate; 15. Push rod. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1:

[0026] Please see Figures 1-6As shown, a rapid demolding mechanism for blow molding of a plastic bucket includes a base 1; a base plate 3 is fixedly connected to the top of the outer wall of the base 1 via a set of support columns 2; a driving device 4 is fixedly connected to the top of the outer wall of the base 1; a threaded shaft 5 is provided at the output end of the driving device 4; a set of connecting plates 16 are slidably connected to the inner side wall of the base plate 3; an arc-shaped side plate 17 is fixedly connected to one side of the inner wall of each set of connecting plates 16; a threaded plate 6 is threadedly connected to the outer side wall of the threaded shaft 5; a linkage block 7 is fixedly connected to the top of the outer wall of the threaded plate 6; a connecting rod 8 is fixedly connected to the bottom of the outer wall of each set of connecting plates 16, and one end of the outer wall of each set of connecting rods 8 is slidably connected to the inner side wall of the linkage block 7. After the plastic bucket is blow molded, the driving device 4 drives the threaded shaft 5 to rotate. Because the threaded shaft 5 is threadedly connected to the threaded plate 6, the rotation of the threaded shaft 5 causes the threaded plate 6 to move upward, which in turn causes the linkage block 7 to move upward. One end of the outer wall is slidably connected to the inner side wall of the linkage block 7. When the linkage block 7 moves upward, the inclined surface of the inner side wall of the linkage block 7 presses against a set of connecting rods 8, causing the set of connecting rods 8 to move in all directions. The set of connecting rods 8 drives the connecting plate 16 to move, causing the connecting plate 16 to slide on the inner side wall of the base plate 3. This causes a set of arc-shaped side plates 17 to be evenly withdrawn in all directions, so that the blow-molded plastic bucket is completely freed from all lateral constraints at the moment of demolding. This prevents the bucket body from adhering to a set of arc-shaped side plates 17, and also reduces the adhesion area, making the bucket body less prone to scratches and reducing the defect rate. This ensures product quality and aesthetics. At the same time, because the arc-shaped side plates 17 are designed to withdraw evenly in all directions, the demolding process is more stable and gentle. This not only simplifies the demolding process but also shortens the time required for a single demolding, effectively improving the continuous production efficiency of blow molding.

[0027] The base plate 3 includes an annular plate 31 and a push rod 32; the outer side wall of the push rod 32 is slidably connected to the inner side wall of the annular plate 31; the push rod 32 is located above the linkage block 7; the inner side wall of the linkage block 7 is inclined; the base plate 3 and a set of arc-shaped side plates 17 form a blow molding space. When the set of arc-shaped side plates 17 are evenly removed to all sides by the upward movement of the linkage block 7, the linkage block 7 continues to move upward. At this time, the linkage block 7 pushes against the push rod 32. The upward movement of the linkage block 7 drives the push rod 32 to move upward, so that the push rod 32 pushes against the blow-molded plastic bucket. As the push rod 32 continues to move upward... As the plastic bucket moves upward, the contact area between the bottom of the plastic bucket and the annular plate 31 gradually decreases until it completely detaches from the supporting surface of the annular plate 31, allowing the bottom of the blow-molded plastic bucket to be demolded from the annular plate 31. At this time, the plastic bucket is suspended in the air under the support of the push rod 32. Together with the removed arc-shaped side plate 17, a 360-degree non-contact demolding environment is formed. This coordinated action of pushing and lateral removal ensures that the plastic bucket maintains a vertical posture throughout the demolding process, effectively preventing tipping or collision caused by the shift of the center of gravity, and further ensuring the integrity of the plastic bucket body.

[0028] The push rod 32 includes a housing 321, a sliding plate 322, and a rod 323. The outer side wall of the sliding plate 322 is slidably connected to the inner side wall of the housing 321. The bottom ends of the outer walls of a set of rods 323 are all fixed to the top ends of the outer walls of the sliding plate 322. The outer side walls of a set of rods 323 are all slidably and sealed to the inner side wall of the housing 321. A connecting block 9 is fixedly connected to one side of the outer wall of the sliding plate 322, and one end of the outer wall of the connecting block 9 is fixed to the bottom end of the outer wall of the base plate 3. When the push rod 32, including the housing 321, the sliding plate 322, and the rod 323, moves the linkage block 7 upward, causing the housing 321 in the push rod 32 to move upward to demold the plastic bucket, the sliding plate 322 is fixed to the bottom of the base plate 3 by the connecting block 9. The slide plate 322 and a set of rods 323 remain stationary. When the shell 321 moves upward, the rods 323 gradually detach from the bottom of the plastic bucket. As the shell 321 moves upward, the top plane of the shell 321 gradually and completely supports the bottom of the plastic bucket. The original support from multiple rods 323 and the top of the shell 321 is changed to the top surface of the shell 321 contacting and supporting the bottom. This avoids local friction scratches on the inner wall of the bucket bottom when the rods 323 are removed. At the same time, it reduces the contact area between the bottom of the plastic bucket and the top rod 32, making it easier to demold the plastic bucket and improving the integrity of the plastic bucket during demolding. In addition, the connecting block 9 will block the top of the inner wall of the shell 321, so that the shell 321 will not continue to move downward when it encounters the connecting block 9.

[0029] A spring 10 is fixedly connected to the bottom of the outer wall of the base plate 3; a square block 11 is fixedly connected to the outer wall of the shell 321; the bottom of the outer wall of the spring 10 is fixedly connected to the top of the outer wall of the square block 11; a damper is provided at the spring 10, and the elastic force of the spring 10 abuts against the square block 11. The square block 11 is fixedly connected to the shell 321, so that the elastic force of the spring 10 cooperates with the support of the connecting block 9, so that when the shell 321 does not encounter the linkage block 7, it is fixed in a fixed position by the connecting block 9 and the spring 10. This makes it difficult for the shell 321 to bulge or dent during the blow molding of the plastic bucket, and makes it difficult for the bottom of the blow-molded plastic bucket to protrude. The defect is that when the linkage block 7 moves the housing 321 upward for demolding, the spring 10 gradually contracts as the housing 321 rises. At this time, the damper begins to play a buffering role to prevent the housing 321 from shaking due to the sudden release of the spring force of the spring 10. After the plastic bucket is completely demolded, the return force of the spring 10 pulls the housing 321 to slowly fall back. The damper controls the falling speed again through resistance, so that the housing 321 gently abuts against the connecting block 9 to avoid equipment wear caused by hard collision. At the same time, it ensures that the housing 321 quickly returns to the fixed position during blow molding, preparing for the next production cycle.

[0030] A set of electric push rods 13 are fixedly connected to the top of the outer wall of the base 1 via a set of fixing rods 12; a square plate 14 is fixedly connected to one end of the outer wall of each set of electric push rods 13; a set of push rods 15 are fixedly connected to one side of the outer wall of each set of square plates 14; multiple sets of push rods 15 are located at the opening and closing points of a set of arc-shaped side plates 17. When the arc-shaped side plates 17 are retracted to all sides under the action of the linkage block 7, exposing the gap, the electric push rods 13 are activated simultaneously, pushing multiple sets of push rods 15 through the square plates 14 to extend into the opening and closing gaps of the arc-shaped side plates 17, effectively peeling off the rough edges or local welded parts of the plastic bucket that may be stuck to the edge of the side plate, avoiding the local damage to the bucket body caused by the adhesion of the side plate edge during traditional demolding. During the stretching deformation, after the arc-shaped side plate 17 completes its retraction, the electric push rod 13 drives the push rod 15 to quickly reset, preventing interference with the upward movement of the ejector rod 32. In the mold closing stage before blow molding, the electric push rod 13 acts in the opposite direction on the arc-shaped side plate 17 through the push rod 15, ensuring that multiple sets of arc-shaped side plates 17 are precisely aligned when closed, eliminating mold gaps, avoiding flash from the plastic melt during molding, further improving the molding accuracy of the plastic bucket, effectively reducing the defect rate in production, and the electric push rod 13 driving the push rod 15 can adjust the position of the plastic bucket, making it less likely for the plastic bucket to shift position, tilt, or collide, causing scratches on the plastic bucket.

[0031] Example 2:

[0032] Please see Figure 7 As shown, this embodiment adds a sensing detection unit and a controller to the basis of embodiment 1 to realize automatic determination of demolding timing and adaptive control of demolding speed.

[0033] This embodiment adds three types of sensors: a thin-film pressure sensor, an infrared temperature sensor, and a magnetic grating ruler, as well as a controller. The controller executes three control processes: demolding readiness determination, variable speed demolding control, and ejection coordination control.

[0034] A thin-film pressure sensor is embedded on the inner wall of a set of arc-shaped side plates 17 to detect the bonding force. A thin-film pressure sensor is embedded on the inner wall of each arc-shaped side plate 17. The sensing surface of the thin-film pressure sensor faces the inside of the blow molding space, that is, towards the plastic bucket wall. The thin-film pressure sensor is used to detect the bonding force between the plastic bucket wall and the arc-shaped side plate 17 in real time.

[0035] For example, when four arc-shaped side plates 17 are used to enclose the blow molding space in this embodiment, four thin-film pressure sensors are embedded on the inner wall surfaces of the four arc-shaped side plates 17 respectively. The four thin-film pressure sensors are evenly distributed in the circumferential direction, so that the controller can simultaneously acquire the adhesion force data between the plastic bucket wall and the arc-shaped side plates 17 in four directions, thereby comprehensively reflecting the spatial distribution of the adhesion state between the plastic bucket wall and the mold. The range of the thin-film pressure sensor is selected according to the typical parameters of the blow molding process. The air pressure in the cavity during the blow molding stage is usually between 0.3 MPa and 0.8 MPa. Therefore, the range of the thin-film pressure sensor is selected to be 0 to 1.5 MPa to ensure that it can cover the complete range of variation from the high adhesion force during the blow molding stage to the low adhesion force after cooling and shrinkage. The output signal of the thin-film pressure sensor is an analog voltage signal, and the voltage range is usually 0 volts to 5 volts. The signal acquisition module of the controller has a built-in analog-to-digital converter to convert the analog voltage signal into a digital quantity for subsequent processing. The conversion resolution is usually 12 bits to 16 bits to ensure the accuracy of pressure measurement.

[0036] An infrared temperature sensor is embedded at the top of the outer wall of the housing 321 to detect the surface temperature of the bottom of the plastic bucket. The temperature measurement range of the infrared temperature sensor is set according to the temperature parameters of the plastic bucket blow molding process. During the blow molding stage, the temperature of the plastic preform is usually between 150 degrees Celsius and 230 degrees Celsius. After cooling, the surface temperature of the plastic bucket gradually decreases to the demolding temperature range of 40 degrees Celsius to 80 degrees Celsius. Therefore, the temperature measurement range of the infrared temperature sensor is selected to be 30 degrees Celsius to 250 degrees Celsius to cover the complete temperature change range from the high temperature of molding to the low temperature of demolding. The response time of the infrared temperature sensor is usually less than 100 milliseconds to meet the requirements of real-time control. Its output signal is also an analog voltage signal or a digital signal. In this embodiment, a digital signal output type is used, which is directly connected to the controller through a serial communication interface to reduce the noise introduced by the signal conversion process.

[0037] For example, when a plastic bucket is blow-molded using high-density polyethylene (HDPE), the Vicat softening temperature of HDPE is approximately 125°C to 130°C. The suitable demolding temperature is typically 40°C to 60°C below the Vicat softening temperature, i.e., a range of 65°C to 90°C. An infrared temperature sensor continuously monitors the surface temperature of the bottom of the plastic bucket. When the detected temperature drops to the aforementioned demolding temperature range, it indicates that the bottom of the plastic bucket has sufficient structural rigidity to withstand the mechanical forces during demolding without deformation. The emissivity parameter of the infrared temperature sensor needs to be set according to the surface characteristics of the plastic bucket material. The surface emissivity of HDPE is typically approximately 0.95. This emissivity parameter is stored internally in the controller and compensated for during temperature calculations to ensure the accuracy of temperature measurements.

[0038] A magnetic scale is fixedly attached to one side of the outer wall of the threaded plate 6, and a magnetic scale reading head that cooperates with the magnetic scale is fixedly attached to the bottom end of the outer wall of the base plate 3. This head is used to detect the axial displacement of the threaded plate 6. The measurement resolution of the magnetic scale is selected according to the control accuracy requirements of the demolding process. In this embodiment, the total stroke of the threaded plate 6 from its initial position to the complete removal of the arc-shaped side plate 17 is usually between 20 mm and 80 mm. The stroke of the linkage block 7 from contacting the ejector rod 32 to the ejector rod 32 completing the ejection action is usually between 10 mm and 40 mm. In order to achieve the control accuracy of the removal speed and ejection of the arc-shaped side plate 17, the following measures are taken. The precise control of the ejection speed of rod 32 is achieved by selecting a magnetic scale with a measurement resolution of 0.01 mm, enabling the controller to acquire the real-time position information of threaded plate 6 with sufficient accuracy and adjust the speed accordingly. The output signal of the magnetic scale is usually a TTL level pulse signal or a sine wave signal. In this embodiment, a sine wave signal is used for output. The controller internally uses an interpolation subdivision circuit to subdivide the signal into higher resolution pulses, further improving the displacement measurement accuracy. The magnetic scale has the characteristics of being oil-resistant and vibration-resistant, making it suitable for long-term stable operation in the complex environment of a blow molding workshop.

[0039] The thin-film pressure sensor, infrared temperature sensor, and magnetic grating reading head are all connected to the controller via signal lines. The controller is fixed to the outer wall of the base 1, located in the lower area of ​​the demolding mechanism, away from the high-temperature area of ​​the blow molding space, to ensure that the controller's electronic components operate in a suitable temperature environment. The controller includes a signal acquisition module, a data processing module, and an execution control module. The signal acquisition module is responsible for receiving the pressure signal output from the thin-film pressure sensor, the temperature signal output from the infrared temperature sensor, and the displacement signal output from the magnetic grating reading head, and converting the analog signals into digital signals for use by the data processing module. The data processing module incorporates a demolding readiness judgment algorithm, a variable speed demolding control algorithm, and an ejection coordination control algorithm, and is responsible for fusing and processing the acquired multi-source sensor data and generating control commands. The execution control module is responsible for converting the control commands generated by the data processing module into drive signals for the drive device 4 and the electric push rod 13, realizing coordinated control of the various execution components of the demolding mechanism.

[0040] The controller uses an industrial-grade microcontroller, which has signal acquisition, data processing and execution control functions, and is electrically connected to the thin-film pressure sensor, infrared temperature sensor, magnetic grating reading head, drive equipment and electric actuator.

[0041] The demolding readiness determination process includes:

[0042] Step S701: Real-time data on the distribution of adhesion force between each arc-shaped side plate 17 and the wall of the plastic bucket is collected using a thin-film pressure sensor.

[0043] During the cooling phase after blow molding, the controller's signal acquisition module continuously reads the pressure signals output by each film pressure sensor at a fixed sampling period. The sampling period is set based on the timescale of the plastic bucket's cooling process, which typically lasts from tens of seconds to several minutes. During this process, the change in adhesion force is relatively slow; therefore, a sampling period of 100 to 500 milliseconds is sufficient for effective tracking of the adhesion force changes. For example, when the sampling period is set to 200 milliseconds, the controller samples each film pressure sensor 5 times per second, accumulating 300 time-series data points over a 60-second cooling period. The sampling period setting must balance data real-time performance and processor load; a sampling period that is too short increases processor burden and is unnecessary, while a sampling period that is too long may cause the critical moment of a sudden change in adhesion force to be missed.

[0044] The pressure values ​​output by each thin-film pressure sensor at the same sampling time constitute the adhesion force distribution data. For example, when this embodiment uses four arc-shaped side plates 17 and each arc-shaped side plate 17 is embedded with a thin-film pressure sensor, at any sampling time, the adhesion force distribution data includes four pressure values, which correspond to the adhesion force magnitudes in four circumferential directions.

[0045] The controller preprocesses the collected contact force distribution data, including filtering and outlier removal. Filtering uses a moving average filtering algorithm, taking the average of the most recent N sampling points as the effective pressure value at the current moment. N is typically 3 to 5 to smooth out sensor noise. Outlier removal uses the Laida criterion: when a sensor reading deviates from the mean by more than three times the standard deviation, it is considered an outlier and replaced with the previous effective value to prevent control misjudgments due to transient sensor interference.

[0046] Step S702: Real-time acquisition of surface temperature data at the bottom of the plastic bucket using an infrared temperature sensor.

[0047] During the cooling phase, the controller's signal acquisition module synchronously reads the temperature signal output by the infrared temperature sensor. The sampling period of the infrared temperature sensor is consistent with that of the thin-film pressure sensor to ensure that adhesion force data and temperature data can be acquired simultaneously at the same sampling moment. The temperature value output by the infrared temperature sensor is the surface temperature data of the bottom of the plastic bucket.

[0048] During the cooling process, the surface temperature of the bottom of the plastic bucket gradually decreases from its high temperature at the end of blow molding. The rate of temperature decrease is influenced by various factors, including the thermal conductivity of the plastic raw material, the bucket wall thickness, and the temperature and flow rate of the cooling medium. For example, when blow molding a 3 mm thick plastic bucket from high-density polyethylene, under natural cooling conditions, it takes approximately 45 to 90 seconds for the surface temperature of the bottom of the bucket to drop from 180 degrees Celsius to 80 degrees Celsius. An infrared temperature sensor continuously tracks this temperature decrease process, providing the controller with real-time temperature status information.

[0049] Step S703: Input the adhesion force distribution data and surface temperature data into the preset fuzzy inference model, output the membership value of cooling sufficiency, and generate a demolding timing signal when the membership value exceeds the preset demolding threshold and send it to the drive device 4.

[0050] The controller's data processing module has a pre-set fuzzy inference model. This model is a computational inference model based on fuzzy set theory and fuzzy logic. Its characteristic is its ability to handle input information with imprecision and uncertainty, and to map multiple input variables to output variables using fuzzy rules. In this embodiment, the fuzzy inference model uses the adhesion force distribution data obtained in step S701 and the surface temperature data obtained in step S702 as inputs, and outputs a cooling sufficiency membership value. The cooling sufficiency membership value is a dimensionless value between 0 and 1. The closer the value is to 1, the more sufficient the cooling of the plastic bucket and the more mature the demolding conditions; the closer the value is to 0, the less sufficient the cooling of the plastic bucket and the less suitable it is for demolding.

[0051] The reason for choosing a fuzzy inference model instead of a simple threshold comparison method to determine the demolding timing is that the demolding readiness state is not determined by a single parameter, but by both the adhesion force and temperature, and these two parameters are coupled. For example, when the temperature at the bottom of the plastic bucket has dropped to a low level but the adhesion force is still high, it may be that the bucket wall is partially pressed against the mold due to uneven shrinkage. In this case, although the temperature condition is met, the mechanical condition is not, and immediate demolding is not advisable. Conversely, when the adhesion force has dropped to a low level but the temperature is still high, it may be that although the bucket wall has partially detached from the mold, the material itself has not yet fully cured. Forcing demolding in this situation may also lead to deformation of the bucket wall. The fuzzy inference model can comprehensively consider the combined state of the two parameters and provide a holistic judgment result, avoiding the misjudgments that may occur with single-parameter threshold determination methods.

[0052] The fuzzy inference model is constructed within the controller as follows: the model consists of four logical modules: an input layer, a fuzzification layer, an inference layer, and a defuzzification layer. The input layer receives three preprocessed feature quantities: the mean of the adhesion force, the coefficient of variation of the adhesion force, and the temperature difference. The fuzzification layer converts these three precise quantities into fuzzy linguistic variables. The inference layer performs logical operations based on a preset fuzzy rule base to obtain the fuzzy state of the output variable. The defuzzification layer converts the fuzzy state into a precise membership value for cooling adequacy.

[0053] The controller compares the cooling adequacy membership value with a preset demolding threshold, which is a constant between 0 and 1. Its specific value is determined through process experiments based on the material properties, wall thickness, and product quality requirements of the plastic bucket. The determination method is as follows: Before formal production, multiple experimental blow molding and demolding operations are performed using the same materials and process parameters. In each experiment, the adhesion force distribution data and surface temperature data at different cooling time points are recorded. Simultaneously, the quality of the demolded plastic bucket is inspected, including indicators such as bucket wall deformation, surface scratches, and dimensional accuracy. The cooling adequacy membership value corresponding to the cooling time point that simultaneously satisfies both qualified demolding quality and optimal demolding efficiency is identified, and this value is used as the preset demolding threshold. For example, when using high-density polyethylene material to blow mold a plastic bucket with a wall thickness of 3 mm, after 20 process experiments, the preset demolding threshold is determined to be 0.82. That is, when the cooling adequacy membership value reaches 0.82, the plastic bucket has sufficient structural rigidity to withstand the demolding load without wasting production time due to excessive cooling.

[0054] When the cooling sufficiency membership value exceeds the preset demolding threshold, the controller's data processing module generates a demolding timing signal. This signal is a logic trigger signal, sent to the drive device 4 via the execution control module, instructing it to start the rotation of the threaded shaft 5, thereby initiating the entire demolding sequence. When the cooling sufficiency membership value has not yet exceeded the preset demolding threshold, the controller does not generate a demolding timing signal, the drive device 4 remains stationary, and the demolding mechanism waits until the cooling sufficiency membership value meets the condition.

[0055] The specific components of a fuzzy inference model include:

[0056] The fuzzy inference model in step S703 specifically includes three sub-steps: step S7031, step S7032, and step S7033, which respectively complete the extraction of mechanical feature quantities, the extraction of thermal feature quantities, and the fuzzy inference operation.

[0057] Step S7031: Extract the mean and dispersion coefficients from the adhesion force distribution data as mechanical characteristic quantities.

[0058] The controller's data processing module performs statistical feature extraction on the adhesion force distribution data collected in step S701. The adhesion force distribution data contains multiple pressure values ​​at each sampling time, the same number as the number of pressure values ​​on the curved side plate 17. The data processing module first calculates the arithmetic mean of these pressure values, defining the arithmetic mean as the average adhesion force. The average adhesion force reflects the average level of overall adhesion between the plastic bucket wall and the mold. For example, when blow molding is completed, the adhesion force in each direction is between 0.4 MPa and 0.6 MPa immediately, with an average adhesion force of approximately 0.5 MPa. After cooling, the adhesion force in each direction gradually decreases to between 0.05 MPa and 0.15 MPa, with an average adhesion force of approximately 0.1 MPa.

[0059] The formula for calculating the average adhesion force is as follows: Let the number of arc-shaped side plates 17 in this embodiment be n. At a certain sampling moment, the adhesion force values ​​output by the n thin-film pressure sensors are F1, F2, and so on up to F... n Then the average adhesion force F avg The calculation formula is: F avg =(F1+F2+…+F n ) / n.

[0060] Discrete coefficients C v The calculation method is as follows: calculate the standard deviation S of n adhesion force values ​​relative to the mean adhesion force. d Standard deviation S d The calculation formula is:

[0061] The radical sign below the square root indicates the square root operation. The discrete coefficients C v Defined as standard deviation S d With the mean adhesion force F avg The ratio of C is calculated using the formula: C v =S d / F avg When the average adhesion force F avg When the value is zero, it indicates that the adhesion force in all directions is zero. At this time, the plastic bucket wall and the curved side plate 17 have completely broken off contact, and the controller will set the discrete coefficient C. v The value is assigned to zero.

[0062] For example: when n equals 4 and the contact force values ​​in the four directions are 0.08 MPa, 0.09 MPa, 0.10 MPa, and 0.09 MPa respectively, the average contact force F avg =(0.08+0.09+0.10+0.09) / 4=0.09 MPa. Standard deviation The calculated result is approximately 0.007 MPa. (Dispersion coefficient) .

[0063] The combination of the mean bonding force and the coefficient of variation is defined as a mechanical characteristic quantity. The mechanical characteristic quantity contains two components: the first component, the mean bonding force, reflects the overall bonding degree, and the second component, the coefficient of variation, reflects the bonding uniformity. The two components describe the mechanical interaction state between the plastic bucket wall and the mold from different perspectives.

[0064] Step S7032: Calculate the difference between the surface temperature data and the preset demolding temperature threshold as a thermal characteristic quantity.

[0065] The controller's data processing module reads the surface temperature data collected in step S702 and performs a difference operation between it and the preset demolding temperature threshold. The calculation result is defined as a thermal characteristic quantity. The preset demolding temperature threshold is a temperature value determined based on the thermodynamic properties of the plastic material used in the plastic bucket. It represents the critical temperature at which the material has sufficient structural rigidity to safely withstand the demolding load when the surface temperature of the plastic bucket drops to this value.

[0066] The method for determining the preset demolding temperature threshold is as follows: consult the technical data manual of the material used in the plastic bucket to obtain the Vicat softening temperature and heat distortion temperature of the material. Set the preset demolding temperature threshold to a temperature value within a certain range below the Vicat softening temperature. This range is determined by finite element thermo-mechanical coupling simulation analysis or process test based on the wall thickness of the plastic bucket and the maximum load it bears during demolding. For example, when using high-density polyethylene material, its Vicat softening temperature is about 127 degrees Celsius. Considering that the maximum ejection stress borne by the bottom of the plastic bucket with a wall thickness of 3 mm during demolding is about 0.05 MPa, finite element simulation analysis determines that when the surface temperature drops to 75 degrees Celsius, the compressive strength margin of the bottom of the bucket is greater than 3 times. Therefore, the preset demolding temperature threshold is set to 75 degrees Celsius.

[0067] The formula for calculating the thermal characteristic quantity dT is: dT = T curr -T demold ; where T curr T represents the surface temperature data of the bottom of the plastic bucket collected by the infrared temperature sensor at the current sampling time. demold This is the preset demolding temperature threshold.

[0068] When the thermal characteristic quantity dT is positive, it means that the current temperature of the bottom of the barrel is still higher than the demolding temperature. When the thermal characteristic quantity dT is zero, it means that the current temperature of the bottom of the barrel has just reached the critical point of the demolding temperature. When the thermal characteristic quantity dT is negative, it means that the current temperature of the bottom of the barrel has been lower than the demolding temperature, that is, the cooling has been sufficient.

[0069] For example, when the preset demolding temperature threshold is 75 degrees Celsius and the current surface temperature collected by the infrared temperature sensor is 95 degrees Celsius, the thermal characteristic quantity dT is +20 degrees Celsius, indicating that the bottom of the plastic bucket still needs further cooling. When the surface temperature drops to 75 degrees Celsius, the thermal characteristic quantity dT is zero, indicating that the critical demolding temperature has been reached. When the surface temperature continues to drop to 65 degrees Celsius, the thermal characteristic quantity dT is -10 degrees Celsius, indicating that the plastic bucket has been sufficiently cooled.

[0070] Step S7033: After fuzzifying the mechanical and thermal characteristic quantities using the triangular membership function, rule matching is performed using the Mamdani inference engine, and the membership value of cooling adequacy is output using the centroid defuzzification method.

[0071] The controller's data processing module performs fuzzification processing on the two components of the mechanical characteristic quantity and the thermal characteristic quantity respectively. Fuzzification processing is the process of mapping precise numerical values ​​to membership values ​​in a fuzzy set. In this embodiment, the triangular membership function is used as the fuzzification tool. The triangular membership function is defined by three parameters.

[0072] The mathematical expression of the triangular membership function is as follows: Let the left endpoint of the triangular membership function be a, the peak point be b, and the right endpoint be c. For the input value x, the formula for calculating the membership value μ(x) output by the triangular membership function is as follows: When x ≤ a, μ(x) = 0; when a < x ≤ b, μ(x) = (xa) / (ba); when b < x ≤ c, μ(x) = (cx) / (cb); when x > c, μ(x) = 0.

[0073] Three fuzzy sets are defined for the average adhesion force: low adhesion force, medium adhesion force, and high adhesion force. The trigonometric membership function parameters for low adhesion force are set based on process experience. For example, when the range is 0 to 1.5 MPa, the left endpoint, peak point, and right endpoint of the trigonometric membership function for low adhesion force are set to 0 MPa, 0 MPa, and 0.2 MPa, respectively; for medium adhesion force, they are set to 0.1 MPa, 0.3 MPa, and 0.5 MPa; and for high adhesion force, they are set to 0.4 MPa, 0.8 MPa, and 1.5 MPa. The above parameter settings are based on statistical analysis from multiple process experiments. The average adhesion force of the plastic bucket after full cooling is usually below 0.15 MPa; the average adhesion force during the middle of the cooling process is usually between 0.2 MPa and 0.4 MPa; and the average adhesion force immediately after blow molding is usually above 0.45 MPa.

[0074] Two fuzzy sets are defined for the coefficient of variation: uniform and non-uniform. The left endpoint, peak point, and right endpoint of the triangular membership function for the uniform set are set to 0, 0, and 0.3, respectively, while those for the non-uniform set are set to 0.2, 0.6, and 1.0, respectively. The above parameter settings are based on statistical data from process experiments: the coefficient of variation for the adhesion force of plastic buckets with normal, uniform shrinkage is typically below 0.15, while the coefficient of variation for the adhesion force of plastic buckets with localized adhesion is typically above 0.35.

[0075] Three fuzzy sets are defined for the thermal characteristic quantities: sufficient temperature, critical temperature, and insufficient temperature. The left endpoint, peak point, and right endpoint of the triangular membership function for sufficient temperature are set to -40°C, -20°C, and 0°C, respectively; the critical temperature is set to -10°C, 0°C, and +15°C, respectively; and the insufficient temperature is set to +5°C, +30°C, and +100°C, respectively. The above parameters are set based on the following principle: a negative value for the thermal characteristic quantity indicates that the surface temperature is below the preset demolding temperature threshold, with a larger negative value indicating more sufficient cooling; a positive value indicates that the surface temperature is still above the preset demolding temperature threshold, with a larger positive value indicating less sufficient cooling.

[0076] After fuzzification, the data processing module performs rule matching using the Mamdani inference engine. The Mamdani inference engine is one of the most widely used inference methods in the field of fuzzy inference. Its working process is as follows: the membership values ​​of each fuzzified input variable are substituted into a preset fuzzy rule base for rule-by-rule matching. The antecedent of each rule describes the fuzzy state combination of the input variables, and the consequent describes the fuzzy state of the output variable.

[0077] In this embodiment, the fuzzy rule base contains multiple rules. For example, some typical rules are as follows: Rule 1: If the average adhesion force is low, the coefficient of variation is uniform, and the thermal characteristic is sufficient temperature, then the cooling adequacy is very sufficient. Rule 2: If the average adhesion force is low, the coefficient of variation is uniform, and the thermal characteristic is critical temperature, then the cooling adequacy is relatively sufficient. Rule 3: If the average adhesion force is medium, the coefficient of variation is uniform, and the thermal characteristic is sufficient temperature, then the cooling adequacy is relatively sufficient. Rule 4: If the average adhesion force is low, the coefficient of variation is non-uniform, and the thermal characteristic is sufficient temperature, then the cooling adequacy is moderate. The reason for this rule is that although the overall adhesion force is low and the temperature is sufficient, a non-uniform coefficient of variation indicates local adhesion, resulting in a higher risk of demolding; therefore, the cooling adequacy evaluation is downgraded. Rule 5: If the average adhesion force is high and the thermal characteristic is insufficient temperature, then the cooling adequacy is insufficient. The above fuzzy rules are based on the following: taking into account the demolding safety and demolding quality under different combinations of fuzzy states of each input variable, the output level of each rule is determined by combining the experience of process experts and experimental verification. The above fuzzy rules are determined by the experience of process experts and experimental verification.

[0078] The output variable, cooling sufficiency, is defined by five fuzzy sets: insufficient, somewhat insufficient, general, somewhat sufficient, and very sufficient. The triangular membership functions of each fuzzy set are uniformly distributed in the universe of discourse from 0 to 1.

[0079] After aggregating the matching results of all rules, the Mamdani inference engine uses centroid defuzzification to transform the aggregated fuzzy output into a precise numerical output. The calculation principle of centroid defuzzification is as follows: the aggregated fuzzy set is regarded as a two-dimensional geometric figure, and the abscissa of the area centroid of the figure is calculated. The abscissa value is the membership value of the cooling sufficiency.

[0080] The calculation formula for the centroid defuzzification method is as follows: Let the membership distribution function of the output fuzzy set obtained after aggregation by the Mamdani inference engine on the cooling sufficiency universe (0 to 1) be: Where y is a variable in the cooling adequacy domain, the formula for calculating the cooling adequacy membership value Y is:

[0081] Here, the integral represents the definite integral operation within the universe of discourse from 0 to 1. In the actual digital calculation of the controller, the above continuous integral operation is implemented using a discretization approximation method, dividing the universe of discourse from 0 to 1 into m discrete points y1, y2, and so on. m The distance between two adjacent discrete points is The discretized calculation formula is:

[0082]

[0083] After simplification, it becomes:

[0084]

[0085] For example, when m is 100, the universe of discourse from 0 to 1 is divided into 100 discrete points with intervals of... The value is 0.01, and the controller calculates μ for each of the 100 discrete points. out The value is then weighted and summed according to the above formula to obtain the membership value Y of the cooling adequacy. This calculation process is completed in the data processing module of the controller within the sampling period.

[0086] The variable speed demolding control process specifically includes steps S901, S902, and S903.

[0087] Step S901: The axial displacement of the threaded plate 6 is acquired in real time through the magnetic grating reading head;

[0088] After receiving the demolding timing signal, the controller executes a start command sent by the control module to the drive device 4. The drive device 4 then rotates the threaded shaft 5, and the threaded plate 6 moves axially upward under the action of the threaded connection. Simultaneously, the controller's signal acquisition module begins to continuously read the displacement signal output by the magnetic grating reading head at a high-frequency sampling period. The sampling period in the variable-speed demolding control stage is much shorter than that in the demolding readiness determination stage. This is because the retraction process of the arc-shaped side plate 17 is short in duration and changes speed rapidly, requiring a higher sampling frequency to ensure control accuracy. For example, the sampling period in the variable-speed demolding control stage is set to 5 to 20 milliseconds. When the sampling period is 10 milliseconds, the controller samples the magnetic grating reading head 100 times per second.

[0089] The displacement signal output by the magnetic grating reading head is converted by the signal acquisition module to obtain the axial displacement of the threaded plate 6. The axial displacement is measured with the initial position of the threaded plate 6 when the drive device 4 starts as the zero point and the upward movement direction as the positive direction. Since the linkage block 7 is fixed to the top of the outer wall of the threaded plate 6, the magnetic grating reading head outputs the axial displacement of the threaded plate 6, which indirectly reflects the radial retraction of the arc-shaped side plate 17.

[0090] Step S902: Based on the axial displacement and adhesion force distribution data, the output speed of the drive device 4 is dynamically adjusted using a feedforward PID composite control algorithm, so that a set of arc-shaped side plates 17 are withdrawn to all sides at a non-linear speed trajectory that is slow at first and then fast.

[0091] The controller's data processing module takes the axial displacement data collected in real time in step S901 and the contact force distribution data collected continuously in step S701 as inputs to the feedforward PID composite control algorithm, calculates the target speed that the drive device 4 should output at the current moment, and sends the target speed command to the drive device 4 through the execution control module.

[0092] The feedforward PID composite control algorithm consists of two parts: a feedforward control loop and a PID feedback control loop. The feedforward control loop uses the average adhesion force in the adhesion force distribution data as the feedforward input. The working principle of the feedforward control loop is as follows: when the average adhesion force is large, it indicates that the adhesion force between the plastic bucket wall and the curved side plate 17 is strong. Based on this, the feedforward control loop lowers the reference value of the target rotation speed, so that the curved side plate 17 is slowly removed at a lower speed, reducing the friction force on the bucket wall surface to avoid scratches. When the average adhesion force gradually decreases, the feedforward control loop correspondingly increases the reference value of the target rotation speed, so that the curved side plate 17 is removed faster to improve demolding efficiency. The gain coefficient of the feedforward control loop is determined through process test calibration. The calibration method is as follows: demolding tests are conducted at different constant speeds under different average bonding force levels. The surface quality of the barrel wall under each combination condition is recorded. The maximum safe speed that can ensure the barrel wall is not scratched under each average bonding force level is found. The correspondence between the average bonding force and the maximum safe speed is fitted as a linear or piecewise linear function. The coefficient of this function is the gain coefficient of the feedforward control loop.

[0093] The PID feedback control loop uses axial displacement as the feedback quantity. The data processing module calculates the expected displacement value at the current moment based on the preset expected displacement-time trajectory. The difference between the expected displacement value and the actual axial displacement acquired in real time in step S901 is defined as the displacement deviation. The PID feedback control loop performs proportional, integral, and derivative operations on the displacement deviation to generate a speed correction quantity. The proportional term generates a correction quantity proportional to the current displacement deviation, used for rapid response to deviation changes. The integral term accumulates the displacement deviation over time and generates a correction quantity to eliminate steady-state error, preventing continuous speed deviation caused by load fluctuations. The derivative term generates a lead correction quantity based on the rate of change of the displacement deviation, used to suppress overshoot and oscillation during speed regulation. The three coefficients of the PID control are the proportional coefficient, integral coefficient, and derivative coefficient, whose values ​​are determined by the classic Ziegler-Nichols tuning method or the engineering trial-and-error method.

[0094] The preset displacement-time expected trajectory is a non-linear curve that is slow at first and then fast. This trajectory is designed based on the following: In the initial stage of demolding, the curved side plate 17 has just begun to retract. At this time, the contact area between the plastic bucket wall and the curved side plate 17 is the largest, the adhesion is strongest, and the risk of scratching is highest. Therefore, the slope of the expected trajectory is relatively small, corresponding to a lower retraction speed. As the curved side plate 17 gradually retracts, the contact area between the plastic bucket wall and the curved side plate 17 gradually decreases, the adhesion gradually decreases, and the risk of scratching gradually decreases. Therefore, the slope of the expected trajectory gradually increases, corresponding to a gradually increasing retraction speed. For example, when the total stroke of the threaded plate 6 is 50 mm, the expected trajectory is set as follows: a low speed of 5 mm / s for the first 10 mm of stroke, a medium speed of 15 mm / s for the 10 mm to 30 mm stroke, and a high speed of 30 mm / s for the 30 mm to 50 mm stroke.

[0095] The output of the feedforward PID composite control algorithm is the target rotational speed V of the drive device 4 at the current moment. target Its calculation formula is: V target =V ff +V pid V ff The output of the feedforward control loop is the speed reference value, V. pid This is the output of the PID feedback control loop, i.e., the speed correction.

[0096] The speed reference value V of the feedforward control loop ff The calculation formula is:

[0097] V max K is the maximum allowable output speed of drive device 4. ff F is the feedforward gain coefficient. avg The average adhesion force at the current moment is the value calculated in step S7031. When the average adhesion force F avg When V is large ff Smaller means a lower reference speed value, when the average contact force F avg When V approaches zero ff Approaching V max That is, the reference speed value approaches its maximum value. The feedforward gain coefficient K ff The unit is the reciprocal of megapascals, and its value is determined through the aforementioned process test calibration method. For example, when V... max It is 200 revolutions per minute and K ff When the average current bonding force F is the reciprocal of 2 MPa, avg If it is 0.3 MPa, then V ff =200×(1-2×0.3)=80 revolutions per minute.

[0098] Speed ​​correction V in PID feedback control pid The calculation formula is:

[0099] , where e(t) is the displacement deviation at the current time t, and e(t) is equal to the expected displacement value minus the actual axial displacement acquired in step S901. K p K is the proportionality coefficient. i K is the integral coefficient. d is the differential coefficient. The displacement deviation is calculated as the time integral from the demolding start time to the current time. In the discretization implementation, the rectangular method is used to accumulate the product of the deviation value in each sampling period and the sampling period for approximate calculation. The displacement deviation is the rate of change over time. In the discretization implementation, it is approximated by subtracting the deviation value of the previous sampling period from the deviation value of the current sampling period and then dividing by the sampling period.

[0100] The tuning of the three PID coefficients adopts the Ziegler-Nichols critical proportional gain method. The specific steps are as follows: First, adjust the integral coefficient K... i and differential coefficient K d Set all values ​​to zero, retain only the proportional control, and gradually increase the proportional coefficient K. p Record the critical proportional coefficient K at this point until the system exhibits sustained oscillations with constant amplitude. pc and oscillation period T c Then, the recommended values ​​for the three coefficients, K, are calculated according to the Ziegler-Nichols empirical formula. p =0.6×K pc K i =2×K p / T c K d =K p ×T c / 8. In practical applications, the recommended values ​​can be fine-tuned and optimized based on the system's response performance.

[0101] Throughout the variable speed demolding control process, the film pressure sensor continuously collects bonding force data, and the feedforward control circuit adjusts the speed reference value in real time accordingly.

[0102] Step S903: When the axial displacement reaches the preset threshold for the removal of the arc-shaped side plate 17, output the signal that the removal of the arc-shaped side plate 17 is complete.

[0103] The controller's data processing module continuously compares the axial displacement collected in real time in step S901 with the preset threshold for the removal of the arc-shaped side plate 17. The threshold for the removal of the arc-shaped side plate 17 is a preset displacement value. The method for determining the threshold for the removal of the arc-shaped side plate 17 is as follows: based on the inclination angle of the inclined surface of the inner wall of the linkage block 7 and the kinematic transmission ratio of the connecting rod 8, the required axial upward movement of the linkage block 7 is calculated when the radial removal of the arc-shaped side plate 17 reaches the minimum radial clearance required for the arc-shaped side plate 17 to completely disengage from the plastic bucket wall. This axial upward movement is the threshold for the removal of the arc-shaped side plate 17. For example, when the minimum radial clearance required for the arc-shaped side plate 17 to completely disengage from the plastic bucket wall is 8 mm and the inclination angle of the inclined surface of the inner wall of the linkage block 7 is 45 degrees, the required axial upward movement of the linkage block 7 is 8 mm. Considering the safety margin, the threshold for the removal of the arc-shaped side plate 17 is set to 10 mm, and the side plate removal completion signal is transmitted to the top-out collaborative control process.

[0104] The top-out collaborative control process includes:

[0105] Step S1001: Based on the signal indicating the completion of the removal of the arc-shaped side plate 17, a set of electric push rods 13 are synchronously triggered to extend to the opening and closing gap of the arc-shaped side plate 17.

[0106] After receiving the signal indicating that the arc-shaped side plate 17 has been removed (output in step S903), the controller's execution control module immediately sends an extension command to a set of electric push rods 13. The set of electric push rods 13 activates synchronously, pushing multiple sets of push rods 15 through their respective connected square plates 14 to extend into the opening and closing gap of the arc-shaped side plate 17. Once the push rods 15 are inserted into the gap between the arc-shaped side plates 17, they contact and peel off any rough edges or partially welded areas of the plastic bucket that may be adhered to the edge of the arc-shaped side plate 17. The extension stroke of the electric push rods 13 is preset based on the width of the opening and closing gap of the arc-shaped side plate 17 and the required position of the push rods 15. The extension speed is limited to a safe speed that will not cause impact damage to the plastic bucket body when the push rods 15 contact the rough edges.

[0107] For example, when this embodiment uses four arc-shaped side plates 17, four opening and closing gaps are formed between the four arc-shaped side plates 17, and four sets of electric push rods 13 and push rods 15 are correspondingly provided. After the signal for the arc-shaped side plate 17 to be removed is triggered, the four sets of electric push rods 13 extend simultaneously, and the four sets of push rods 15 extend into the four gaps respectively to peel off any burrs that may exist in each gap. The synchronous operation design ensures that the burr removal action in all directions is completed simultaneously, so that the plastic bucket is released from the burr adhesion constraint in all directions at the same time, avoiding the plastic bucket from shifting due to uneven force caused by peeling on one side first.

[0108] In step S1002, the axial displacement is continuously acquired through the magnetic grating reading head. When the axial displacement reaches the preset contact displacement value between the linkage block 7 and the push rod 32, it is determined that the linkage block 7 has contacted the push rod 32 and an ejection start signal is output.

[0109] In step S1001, while the electric push rod 13 performs the burr removal action, the drive device 4 continues to drive the threaded shaft 5 to rotate, and the threaded plate 6 and the linkage block 7 continue to move upward. At this time, the arc-shaped side plate 17 has been completely removed into place, and the continued upward movement of the linkage block 7 no longer causes further radial movement of the arc-shaped side plate 17. The upward movement of the linkage block 7 begins to approach the bottom of the housing 321 of the top rod 32 located above it.

[0110] The controller's signal acquisition module continues to acquire the axial displacement of the threaded plate 6 through the magnetic grating reading head. The data processing module compares the current axial displacement with a preset contact displacement value. The preset contact displacement value is a pre-defined displacement value, and its corresponding physical meaning is: when the axial displacement of the threaded plate 6 reaches this value, the top of the linkage block 7 just contacts the bottom of the ejector rod 32 housing 321, that is, the gap between the linkage block 7 and the ejector rod 32 is eliminated. The preset contact displacement value is determined as follows: during the assembly stage of the demolding mechanism, the axial distance between the top of the linkage block 7 and the bottom of the ejector rod 32 housing 321 at the initial position is actually measured using a measuring tool, and this distance value is the preset contact displacement value. For example, when the axial distance between the top of the linkage block 7 and the bottom of the ejector rod 32 housing 321 at the initial position is 15 mm, the preset contact displacement value is set to 15 mm.

[0111] When the axial displacement reaches the preset contact displacement value, the data processing module determines that the linkage block 7 has contacted the push rod 32 and generates an ejection start signal. The ejection start signal is a logic trigger signal, which indicates that the upward movement of the linkage block 7 has transitioned from the stage of retraction of the arc-shaped side plate 17 to the stage of ejection of the push rod 32. The subsequent upward movement of the linkage block 7 will directly push the push rod 32 upward and apply an ejection force to the bottom of the plastic bucket.

[0112] In step S1003, based on the ejection start signal, the controller queries a preset temperature ejection speed mapping table according to the real-time bottom temperature collected by the infrared temperature sensor, determines the corresponding ejection speed value, and controls the output speed of the drive device 4 accordingly, so that the ejector rod 32 moves upward at a uniform speed according to the ejection speed value to complete the demolding of the bottom of the plastic bucket.

[0113] After receiving the ejection start signal output in step S1002, the controller's data processing module reads the real-time bottom temperature value collected by the infrared temperature sensor at the current moment. The data processing module inputs this bottom temperature value into a preset temperature ejection speed mapping table for lookup to obtain the ejection speed value corresponding to the current bottom temperature.

[0114] The temperature-ejection-speed mapping table is a pre-established one-dimensional lookup table. Its input variable is the bottom temperature of the bucket, and its output variable is the ejection speed. The mapping table is established as follows: Before formal production, multiple sets of process experiments are conducted using the same materials and process parameters. In each set of experiments, demolding operations are performed at different constant ejection speeds under different bottom temperature levels. The deformation and surface quality of the bottom of the demolded plastic buckets are then inspected to find the maximum safe ejection speed that can ensure the bottom of the bucket does not deform or scratch at each bottom temperature level. The pairing data of each bottom temperature and its corresponding maximum safe ejection speed are then entered into the mapping table.

[0115] The mapping table reflects the following physical law: the higher the temperature of the bottom of the bucket, the lower the elastic modulus and yield strength of the plastic material, and the weaker the ability of the bottom of the bucket to withstand the ejection force without deformation. For example, when the temperature of the bottom of the bucket is 85 degrees Celsius, the corresponding ejection speed is 3 mm / s; when the temperature of the bottom of the bucket is 75 degrees Celsius, the corresponding ejection speed is 6 mm / s; and when the temperature of the bottom of the bucket is 65 degrees Celsius, the corresponding ejection speed is 10 mm / s.

[0116] The controller's execution control module calculates the target rotational speed that the drive device 4 should output based on the queried ejection speed value, and sends the target rotational speed command to the drive device 4. The drive device 4 operates at the target rotational speed, and the ejector rod moves upward at a uniform speed to complete the demolding of the bottom of the plastic bucket.

[0117] During the ejection process, the controller continues to collect axial displacement data via a magnetic grating reading head to monitor the upward stroke of the ejector rod 32. When the axial displacement reaches the preset ejection completion threshold, the controller instructs the drive device 4 to stop rotating, and the entire demolding process ends. The ejection completion threshold is determined based on the upward stroke of the ejector rod 32 required for the bottom of the plastic bucket to completely detach from the annular plate 31.

[0118] The lookup method for the temperature ejection velocity mapping table is as follows. Suppose the mapping table stores m1 sets of temperature-velocity data pairs, representing the velocity V1 corresponding to temperature T1 in the first set, the velocity V2 corresponding to temperature T2 in the second set, and so on up to the m1th set of temperature T... m1 Corresponding speed V m1 The data sets are arranged from lowest to highest temperature. When the real-time bottom temperature T collected by the infrared temperature sensor... curr The two adjacent sets of data T in the mapping table i and T i+1 When the time interval is reached, the corresponding ejection velocity value V is calculated using linear interpolation. out The linear interpolation formula is:

[0119] ;

[0120] When the real-time bottom temperature T curr When the temperature is below the lowest temperature T1 in the mapping table, the ejection velocity value V outTake the maximum speed V1 from the mapping table. When the real-time barrel bottom temperature T... curr When the temperature is higher than the highest temperature in the mapping table, the ejection velocity value V out Take the minimum speed from the mapping table.

[0121] After the plastic bucket is blow-molded, it enters the cooling stage. The controller enters the demolding ready judgment state. During the cooling stage, the controller executes steps S7031 to S7033 in sequence. When the cooling sufficiency membership value exceeds the preset demolding threshold, a demolding timing signal is generated.

[0122] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A quick demolding mechanism for blow molding of plastic buckets, comprising a base (1); a bottom plate (3) is fixedly connected to the top of the outer wall of the base (1) by a set of support columns (2); a driving device (4) is fixedly connected to the top of the outer wall of the base (1); and a threaded shaft (5) is provided at the output end of the driving device (4); characterized in that, The inner wall of the base plate (3) is slidably connected to a set of connecting plates (16); one side of the inner wall of the set of connecting plates (16) is fixedly connected to an arc-shaped side plate (17); the outer wall of the threaded shaft (5) is threadedly connected to a threaded plate (6); the top of the outer wall of the threaded plate (6) is fixedly connected to a linkage block (7); the bottom of the outer wall of the set of connecting plates (16) is fixedly connected to a connecting rod (8), and one end of the outer wall of the set of connecting rods (8) is slidably connected to the inner wall of the linkage block (7).

2. The rapid demolding mechanism for blow molding of plastic buckets according to claim 1, characterized in that, The base plate (3) includes an annular plate (31) and a top rod (32); the outer side wall of the top rod (32) is slidably connected to the inner side wall of the annular plate (31); the top rod (32) is located above the linkage block (7); the inner side wall of the linkage block (7) is inclined; the base plate (3) and a set of arc-shaped side plates (17) form a blow molding space.

3. The rapid demolding mechanism for blow molding of plastic buckets according to claim 2, characterized in that, The top rod (32) includes a housing (321), a sliding plate (322), and a rod (323); the outer side wall of the sliding plate (322) is slidably connected to the inner side wall of the housing (321); the bottom ends of the outer walls of a group of rods (323) are all fixedly connected to the top ends of the outer walls of the sliding plate (322); the outer side walls of a group of rods (323) are all slidably and sealed to the inner side wall of the housing (321); a connecting block (9) is fixedly connected to one side of the outer wall of the sliding plate (322), and one end of the outer wall of the connecting block (9) is fixedly connected to the bottom end of the outer wall of the base plate (3).

4. The rapid demolding mechanism for blow molding of plastic buckets according to claim 3, characterized in that, A spring (10) is fixed to the bottom of the outer wall of the base plate (3); a square block (11) is fixed to the outer wall of the housing (321); the bottom of the outer wall of the spring (10) is fixed to the top of the outer wall of the square block (11); a damper is provided at the spring (10).

5. The rapid demolding mechanism for blow molding of plastic buckets according to claim 4, characterized in that, A set of electric push rods (13) is fixedly connected to the top of the outer wall of the base (1) by a set of fixing rods (12); a square plate (14) is fixedly connected to one end of the outer wall of the set of electric push rods (13); a set of push rods (15) is fixedly connected to one side of the outer wall of the set of square plates (14); multiple sets of push rods (15) are respectively located at the opening and closing points of a set of arc-shaped side plates (17).

6. The rapid demolding mechanism for blow molding of plastic buckets according to claim 5, characterized in that, A thin-film pressure sensor is embedded on the inner wall surface of a set of arc-shaped side plates (17); an infrared temperature sensor is embedded on the top of the outer wall of the housing (321); a magnetic grating ruler is fixed to one side of the outer wall of the threaded plate (6); a magnetic grating reading head that cooperates with the magnetic grating ruler is fixed to the bottom of the outer wall of the base plate (3); the thin-film pressure sensor, the infrared temperature sensor and the magnetic grating reading head are all connected to a controller; the controller is fixed to the outer wall of the base (1).

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