Multilayer continuous coextrusion hollow machine and its forming method

Abstract

The application discloses a multi-layer continuous co-extrusion hollow machine, a lower machine frame is fixedly connected to the bottom of an upper platform, a plurality of electric control machine heads are vertically and penetratively arranged on the upper platform, three groups of horizontally arranged extrusion devices of inner layer, middle layer and outer layer are arranged on the upper platform, discharge outlets of the three groups of extrusion devices are connected with the plurality of electric control machine heads, and feeding devices are arranged at feeding inlets of the extrusion devices; a vertical conveying and cutting mechanism matched with the plurality of electric control machine heads is fixedly connected to the bottom of the upper platform, a mold closing mechanism is arranged below the vertical conveying and cutting mechanism, a blowing device is arranged on the mold closing mechanism, and a mechanical hand is fixedly connected to the bottom end of the vertical conveying and cutting mechanism. The forming method of the multi-layer continuous co-extrusion hollow machine avoids problems such as shaking of a parison during horizontal conveying, stretching during a parison transfer process and the like, guarantees production efficiency and forming quality of plastic hollow blow-molded products, and has the characteristics of high efficiency and energy saving, high stability, continuous multi-layer co-extrusion, parison electric wall thickness control and the like.

Description

Technical Field

[0001] This invention belongs to the technical field of blow molding equipment, specifically relating to a multi-layer continuous co-extrusion blow molding machine and a molding method for the multi-layer continuous co-extrusion blow molding machine. Background Technology

[0002] Multi-layer continuous co-extrusion hollow machine relies on multi-layer co-extrusion and continuous molding technology. Through multiple extrusion devices, plastic melts with different properties are stacked into tubular composite preforms through multiple die heads, and continuously transported to the product mold station for air blowing and shaping, so as to realize the large-scale production of multi-layer and multi-functional hollow products.

[0003] Currently, the dual-station continuous hollow blow molding machine achieves double the production capacity due to its continuous extrusion without interruption and efficient alternating molding at the dual-mold-closing stations. However, the dual-station mold-closing mechanism of this equipment is symmetrically arranged. Due to the limitations of the overall equipment layout and clamping force distribution, it is difficult to adapt to the continuous co-extrusion production of 100-160 liter three-layer hollow products. Such large-sized products require greater clamping force and longer cooling time, which cannot be matched by the alternating rhythm of the dual stations. In addition, the problem of sagging due to the self-weight of the parison in continuous extrusion is aggravated with the increase of length. The dual-station has higher requirements for the control of the parison extrusion length. Excessively long parisons are prone to forming deviations between the two stations. Therefore, it is only suitable for the production of small-sized products. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-layer continuous co-extrusion hollow machine that is energy-saving, stable, and capable of continuous multi-layer co-extrusion.

[0005] Another object of the present invention is to provide a molding method for a multi-layer continuous co-extrusion hollow machine.

[0006] The technical solution adopted in this invention is a multi-layer continuous co-extrusion blow molding machine, including an upper platform, a lower frame fixed to the bottom of the upper platform, a multi-layer electrically controlled die head vertically installed on the upper platform, three sets of horizontally arranged extrusion devices (inner layer, middle layer, and outer layer) on the upper platform, the discharge ports of the three sets of extrusion devices connected to the multi-layer electrically controlled die head, and a feeding device provided at the feed port of the extrusion device; a vertical conveying and cutting mechanism cooperating with the multi-layer electrically controlled die head is fixed to the bottom of the upper platform, a mold closing mechanism is provided below the vertical conveying and cutting mechanism, an inflation device is installed on the mold closing mechanism, and a robot arm is fixed to the bottom end of the vertical conveying and cutting mechanism.

[0007] The invention is further characterized by: The barrel axes of the inner and outer extrusion units are symmetrically distributed at an angle in the same plane, with the middle extrusion unit located between them. The mold closing mechanism's opening and closing direction is parallel to the barrel axis of the middle extrusion unit.

[0008] The lower frame is a high-rigidity frame structure consisting of four vertical columns and horizontal and longitudinal cross braces connected by high-strength bolts, and the upper platform is equipped with guardrails around its perimeter.

[0009] A safety pedal is installed on one side of the upper platform, and a protective device is installed on the outside of the mold closing mechanism.

[0010] The multi-layer electric control head includes an integrated first servo motor and electric cylinder. The main body of the electric cylinder is a planetary roller screw pair. The output shaft of the electric cylinder is connected to a mandrel through a flange. The end of the mandrel is connected to a mandrel mold, and the mandrel mold is fitted with a die. The cylinder body is connected to the upper platform through adjustable support bolts. The cylinder body has three sets of independent feed ports at 90° intervals along the circumference. The three sets of independent feed ports are connected to the discharge ports of the three extrusion devices through transition sections with flanges at both ends.

[0011] The extrusion unit includes a barrel, inside which a feed screw is installed. One end of the feed screw is connected to a gearbox, and the input end of the gearbox is connected to an energy-saving motor via a coupling. The outer wall of the barrel is equipped with multi-component zone-controlled energy-saving heaters. The barrel is also equipped with a barrel inlet and a circulating water cooling device welded to the barrel to form an annular sealed cavity. The feed screw diameter and energy-saving motor power specifications are different for the inner, outer, and middle extrusion units.

[0012] The mold closing mechanism includes a base, on which parallel linear guide rails are provided. From left to right, a left template, a middle template, a synchronization mechanism, and a right pull arm are slidably installed on the linear guide rails. A pull rod is passed between the ends of the left template and the right pull arm on the same side. The two pull rods are parallel to each other. A mold locking cylinder is fixedly connected to the center of the right pull arm. The output end of the mold locking cylinder is connected to the middle template. The synchronization mechanism includes a gear and two racks. The racks are distributed on the left and right sides of the gear in a central distribution. The end of one rack is connected to the bottom of the middle template, and the end of the other rack is connected to the bottom of the right pull arm. The gear is covered with a housing. A drive motor is fixedly connected to the base, and a trapezoidal lead screw assembly is connected to the output end of the drive motor. The lead screw nut of the trapezoidal lead screw assembly is fixedly connected to the housing of the synchronization mechanism.

[0013] The inflation device is connected to the base and is located directly below the multi-layer electric control head, on the center line between the left template and the middle template. The inflation head of the inflation device is a telescopic structure.

[0014] The vertical conveying and cutting mechanism includes a mounting frame that is vertically fixed to the upper platform. The frame is equipped with a vertical guide rail, and a vertical conveying device is installed inside the vertical guide rail. A second servo motor is installed at the top of the frame, and the second servo motor drives the vertical conveying device to move vertically up and down. The vertical conveying device is equipped with a clamping and cutting device for clamping, releasing and cutting materials. The clamping and cutting device is located directly below the multi-layer electronically controlled machine head. The robotic arm is fixed to the bottom of the mounting frame via a positioning bracket, and is set parallel to the clamping and cutting device.

[0015] Another technical solution adopted in this invention is: a molding method for a multi-layer continuous co-extrusion hollow machine, which uses the above-mentioned multi-layer continuous co-extrusion hollow machine and includes the following steps: The raw material is fed into the extrusion unit to melt, and then conveyed by the extrusion unit to the multi-layer electronically controlled die head to be compounded into a three-layer melt. The melt is extruded to form a preform and the wall thickness is adjusted. After the preform meets the standard, it is clamped and cut by the vertical conveying and cutting mechanism. It is then vertically conveyed into the mold of the mold closing mechanism. The bottom of the preform is fitted with an inflation head. After the mold is closed, the inflation device inflates and forms the preform. The vertical conveying and cutting mechanism rises and resets. The robot arm moves forward to clamp the bottom of the hollow product. After the mold closing mechanism opens the mold, the robot arm removes the blown hollow product from the mold and releases it, thus completing the removal of the product.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The multi-layer continuous co-extrusion hollow extruder of this invention features three extrusion units—inner, middle, and outer layers—all equipped with energy-saving motors directly driven, effectively reducing overall machine energy consumption. The transition between the outer and inner extrusion units and the electronically controlled die head adopts an obtuse-angle transition structure, effectively shortening the melt conveying path and reducing local melt pressure. The electronically controlled die head uses electric servo control, achieving micron-level displacement accuracy to ensure uniform product wall thickness. The planetary roller screw main structure effectively suppresses vibration and resists deviations in repeatability positioning accuracy caused by melt back pressure. The electrically controlled die head continuously extrudes three layers of preforms. The preforms are then vertically fed into a single-station mold closing mechanism using servo control technology. This avoids problems such as easy shaking during transverse transport of the preforms and stretching during the preform transfer process, ensuring the production efficiency and molding quality of hollow plastic blow-molded products. It features high efficiency and energy saving, high stability, continuous multi-layer co-extrusion, and electric wall thickness control of the preforms. The molding method of the multi-layer continuous co-extrusion hollow machine of the present invention realizes the fully automated production from plastic chemical raw materials to product molding, and can complete the continuous co-extrusion blow molding of 100-160 liter three-layer hollow products; the produced products can meet the packaging requirements of food, medicine, electronic chemicals, etc., as well as the packaging requirements of adding PCR raw materials (post-consumer recycled plastics), which greatly satisfies the multi-performance requirements of the products. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the multi-layer continuous co-extrusion hollow extruder of the present invention; Figure 2 This is a top view of the multi-layer continuous co-extrusion hollow extruder of the present invention; Figure 3 This is a schematic diagram of the extrusion device structure of the present invention; Figure 4 This is a schematic diagram of the multi-layer electronically controlled machine head structure of the present invention; Figure 5This is a schematic diagram of the vertical conveying and cutting device of the present invention; Figure 6 This is a schematic diagram of the mold closing mechanism of the present invention.

[0018] In the diagram, 1. Upper platform, 2. Lower frame, 3. Inner extrusion unit; 4. Intermediate extrusion unit; 401. Heater; 402. Barrel; 403. Feed screw; 404. Gearbox; 405. Coupling; 406. Energy-saving motor; 4021. Barrel inlet; 4022. Cooling device; 5. Outer extrusion device; 6. Multi-layer electronically controlled die head; 601. First servo motor; 602. Electric cylinder; 603. Flange; 604. Mandrel; 605. Cylinder body; 606. Die; 607. Mandrel; 608. Support bolt; 7. Vertical conveying and cutting mechanism; 701. Second servo motor; 702. Clamping and cutting device; 703. Mounting frame; 704. Vertical conveying device; 8. Mold closing mechanism; 801. Left mold plate; 802. Tie rod; 803. Middle mold plate; 804. Right tie arm; 805. Mold locking cylinder; 806. Synchronization mechanism; 807. Base; 808. Drive motor; 809. Trapezoidal screw assembly; 810. Linear guide rail; 9. Robotic arm, 10. Inflating device, 11. Protective device, 12. Safety pedal, 13. Feeding device. Detailed Implementation

[0019] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] Example 1 The multi-layer continuous co-extrusion hollow extruder of the present invention has the following structure: Figure 1 and Figure 2 As shown, it mainly consists of an upper platform 1, a lower frame 2, an inner extrusion device 3, a middle extrusion device 4, an outer extrusion device 5, a multi-layer electrically controlled die head 6, a vertical conveying and cutting mechanism 7, a mold closing mechanism 8, a robotic arm 9, an inflation device 10, and a feeding device 13.

[0021] The upper platform 1 is installed at the top of the lower frame 2 and is arranged horizontally and parallel to the ground. A multi-layer electric control head 6 is vertically installed on the upper platform 1. The inner extrusion device 3, the middle extrusion device 4, and the outer extrusion device 5 are arranged horizontally on the upper platform 1. The discharge ports of the three extrusion devices are connected to the multi-layer electric control head 6. The feed port of the extrusion device is equipped with a feeding device 13. The vertical conveying and cutting mechanism 7 is fixed to the bottom of the upper platform 1 and works with the multi-layer electric control head 6 to perform clamping and conveying operations. A mold closing mechanism 8 is set below the vertical conveying and cutting mechanism 7. A blower 10 is installed on the mold closing mechanism 8. A robot arm 9 is fixed to the bottom of the vertical conveying and cutting mechanism 7.

[0022] Example 2 Based on Example 1, such as Figure 1 As shown, the lower frame 2 serves as the load-bearing foundation of the entire machine. It consists of four vertically distributed columns and horizontal and longitudinal cross braces connected together by high-strength bolts to form a high-rigidity frame structure, ensuring the stability of the equipment during operation.

[0023] The upper platform 1 is equipped with guardrails around its perimeter to effectively prevent personnel and debris from falling from height and ensure operational safety. A safety step 12 is located on one side of the upper platform 1 for easy access by equipment installation and maintenance personnel.

[0024] A protective device 11 is provided on the outer side of the left end of the mold closing mechanism 8 to prevent mechanical damage.

[0025] Example 3 Based on Example 2, such as Figure 1 and Figure 4 As shown, the multi-layer electrically controlled machine head 6 includes a first servo motor 601 mounted on top. The first servo motor 601 and the electric cylinder 602 are integrated into a single unit. The main body of the electric cylinder adopts a planetary roller screw pair, which can achieve micron-level displacement accuracy and ensure the uniformity of the product wall thickness. The end of the output shaft of the electric cylinder 602 is rigidly connected to the mandrel 604 through a flange 603. The end of the mandrel 604 is connected to a core mold 607, which is fitted with a die 606. By dynamically adjusting the gap between the core mold 607 and the die 606, precise electric wall thickness control of the preform can be achieved, meeting the wall thickness distribution requirements of complex products.

[0026] The multi-layer electric control die head 6 is installed vertically. The cylinder body 605 of the electric cylinder 602 is connected to the column of the upper platform 1 through four sets of adjustable support bolts 608, which facilitates precise adjustment of the die head's level. Along the circumference, the cylinder body 605 of the multi-layer electric control die head 6 has three independent feed ports of inner, middle and outer layers at 90° intervals. These ports are rigidly connected to the discharge ports of the inner extrusion device 3, middle extrusion device 4 and outer extrusion device 5 through transition sections with flanges at both ends. After being plasticized and conveyed by the extrusion device, the material enters the inner, middle and outer flow channels inside the multi-layer electric control die head 6 through the feed ports for compounding, ensuring the sealing and stability of the material conveying, and extruding to form a tubular three-layer preform.

[0027] Example 4 Based on Example 3, such as Figure 1 and Figure 2 As shown, the inner extrusion unit 3, the middle extrusion unit 4, and the outer extrusion unit 5 are all arranged horizontally, that is, the barrel axis is strictly horizontally aligned with the plane of the upper platform 1. The barrel axes of the inner extrusion unit 3 and the outer extrusion unit 5 are symmetrically distributed at an angle within the same plane. The middle extrusion unit 4 is arranged between the two, which effectively shortens the melt conveying path, reduces local melt pressure, and helps to improve product quality and production efficiency.

[0028] The mold closing mechanism 8 has a mold opening and closing direction that is parallel to the cylinder axis of the middle extrusion device 4.

[0029] Example 5 Based on Example 4, such as Figure 3 As shown, the extrusion device includes a barrel 402, inside which an adjustable-speed feed screw 403 is installed. The barrel 402 is rigidly connected to a gearbox 404 via an end flange. The barrel 402 is equipped with a feed inlet 4021 and a circulating water cooling device 4022 welded to the barrel 402 to form an annular sealed cavity, which effectively controls the temperature of the feeding section and prevents premature melting of the plastic raw material. The end of the feed screw 403 is precisely fitted to the output end of the gearbox 404. A multi-section, zone-controlled energy-saving heater 401 is arranged on the outer wall of the barrel 402, employing a zone-controlled temperature design to ensure that the plastic raw material is rapidly and uniformly heated and melted, and to achieve precise temperature maintenance within the set process parameters. An energy-saving motor 406 is directly connected to the input end of the gearbox 404 via a coupling 405, resulting in high transmission efficiency and low operating noise.

[0030] The electric control head adopts electric servo control, which can achieve micron-level displacement accuracy and ensure the uniformity of product wall thickness. The planetary roller screw main structure effectively suppresses vibration and resists the deviation of repeated positioning accuracy caused by melt back pressure.

[0031] The middle-layer extrusion unit 4, the inner-layer extrusion unit 3, and the outer-layer extrusion unit 5 have basically the same structure. The core difference lies in the diameter of the feeding screw and the power specifications of the energy-saving motor. The extrusion unit adopts an integrated mechanical mechanism, optimizes the traditional processing path, and has significant characteristics such as high conveying efficiency, low energy consumption, and uniform plasticization.

[0032] The mold closing mechanism 8 is installed directly below the multi-layer electric control die head 6. It is strictly parallel to the barrel axis of the middle extrusion device 4 along the mold opening and closing direction to ensure the centering of the parison when it enters the mold and effectively improve the molding accuracy of the product.

[0033] The inner, middle, and outer extrusion units are all equipped with energy-saving motors for direct drive, effectively reducing the overall energy consumption of the machine. The transition between the outer and inner extrusion units and the electronic control die head adopts an obtuse angle transition connection structure, which effectively shortens the melt delivery path and reduces local melt pressure.

[0034] The electrically controlled die head continuously extrudes three layers of preforms. Servo control technology vertically feeds the preforms into a single-station mold closing mechanism, avoiding problems such as easy shaking during lateral transport of the preforms and stretching during the preform transfer process. This ensures the production efficiency and molding quality of hollow plastic blow-molded products and features high efficiency and energy saving, high stability, continuous multi-layer co-extrusion, and electric preform wall thickness control.

[0035] Example 6 Based on Example 5, such as Figure 6 As shown, the mold clamping mechanism 8 includes a base 807, on which parallel linear guide rails 810 are provided. The left template 801, the middle template 803, the synchronization mechanism 806, and the right pull arm 804 are sequentially mounted on the linear guide rails 810 via sliders. A pull rod 802 is respectively inserted between the ends of the left template 801 and the right pull arm 804 on the same side. The two pull rods 802 are arranged in parallel. A circular hole is opened in the center of the right pull arm 804 for fixing the mold clamping cylinder 805. The piston rod head of the mold clamping cylinder 805 is fixedly connected to the middle template 803, which can effectively provide a stable mold clamping force.

[0036] The left template 801, middle template 803, synchronization mechanism 806, right pull arm 804 and other components are installed on the base 807 through linear guide rail 810, which has high motion accuracy and fast response speed.

[0037] The synchronization mechanism 806 is arranged between the middle template 803 and the right pull arm 804. It mainly includes a gear and two racks. The racks are distributed on the left and right sides of the gear in a central distribution. The end of one rack is fixedly connected to the bottom of the middle template 803, and the end of the other rack is fixedly connected to the right pull arm 804. The gear is equipped with a housing, which is mounted on the slider of the linear guide rail 810 through a bracket.

[0038] When the piston of the mold-locking cylinder 805 extends, the left mold plate 801 and the right pull arm 804 move in the same direction. Under the action of the synchronization mechanism 806, the middle mold plate 803 moves in the opposite direction to the right pull arm 804, ensuring the synchronization of the mold plates when opening and closing, and avoiding mold wear or product defects caused by uneven force.

[0039] A drive motor 808 is fixedly connected to the base 807. A trapezoidal lead screw assembly 809 is connected to the output end of the drive motor 808. The trapezoidal lead screw assembly 809 is fixedly installed on the base 807. The lead screw nut of the trapezoidal lead screw assembly 809 is fixedly connected to the housing of the synchronization mechanism 806.

[0040] The drive motor 808 drives the trapezoidal lead screw assembly 809, which enables the main components such as the left template 801, the middle template 803, and the right pull arm 804, which are mounted on the slider of the linear guide rail 810, to slide smoothly along the linear guide rail 810 relative to the base 807. This is used to change molds of different specifications and adapt to the production needs of products of multiple specifications.

[0041] The blow molding device 10 is fixed on the base 807 of the mold clamping mechanism 8, located on the center line between the left and middle mold plates, and directly below the multi-layer electric control head 6. The blow molding head adopts a telescopic structure, which can quickly extend into the mold after the parison is in place, and realize the blow molding of the product through high-pressure gas, ensuring stable blow molding pressure and uniform product wall thickness.

[0042] like Figure 5 As shown, the vertical conveying and cutting mechanism 7 mainly consists of a servo motor 701, a clamping and cutting device 702, a mounting frame 703, and a vertical conveying device 704. The mounting frame 703 is vertically fixed to the upper platform 1 with high-strength screws and is set on one side of the multi-layer electric control machine head 6 to support all components. The second servo motor 701 is installed at the top of the mounting frame 703 to provide precise power output to the vertical conveying device 704 and drive the vertical conveying device 704 to rise and fall vertically.

[0043] The mounting frame 703 is provided with a vertical guide rail, and the vertical conveying device 704 is installed in the vertical guide rail as a carrier for the clamping and cutting device 702.

[0044] The clamping and cutting device 702 is installed on the sliding unit of the vertical conveying device 704, which can realize high-speed and stable lifting action and is responsible for the clamping, releasing and cutting of materials.

[0045] The robotic arm of the clamping and cutting device 702 is located directly below the multi-layer electrically controlled machine head 6, and is used to stably clamp and vertically transport the blank. The bottom of the mounting frame 703 is fixedly connected to the positioning bracket of the robot arm 9 with high-strength screws. The clamping device of the robot arm 9 and the robotic arm of the cutting device 702 are arranged strictly in parallel. This ensures that the parison remains vertical during transportation, cutting, and subsequent inflation, effectively preventing sagging and tensile deformation caused by the parison's own weight, and providing high-precision parison posture assurance for subsequent molding processes.

[0046] The clamping and cutting device 702 includes: Main support frame: rigidly connected to the vertical conveying device 704, providing an installation foundation for the clamping and cutting mechanism.

[0047] Clamping and releasing mechanism: It includes a pair of symmetrically arranged robotic arms, a cylinder drive unit, and a guide rail to achieve the clamping and releasing of materials.

[0048] Cutting mechanism: It integrates a cutter, a blade holder, and a drive cylinder, and is located next to the robotic arm to complete the material cutting action.

[0049] Linkage control: The clamping and cutting actions are linked in sequence to ensure that the clamping is stable before cutting and the device is reset after cutting.

[0050] The vertical conveying device 704 specifically includes: Lifting slider: It works with the 703 guide rail of the mounting frame to achieve vertical sliding.

[0051] Transmission mechanism: A ball screw driven by a second servo motor 701 converts rotary motion into linear lifting motion.

[0052] The support platform is fixed to the clamping and cutting device 702 and rises and falls synchronously with the slider.

[0053] Limit and buffer: Configure upper and lower limit switches and buffers to prevent overtravel and impact.

[0054] Robotic arm 9 includes: Connection bracket: rigidly connected to the mounting frame 703, providing a stable mounting base for the robot arm 9.

[0055] Clamping device: includes a pair of symmetrically arranged toothed clamps, cylinder drive, and guide rail, to achieve clamping and releasing of the product.

[0056] Transmission mechanism: Includes servo motor, synchronous belt, synchronous pulley, etc. The clamping device is fixedly connected to the synchronous belt, the servo motor drives the synchronous pulley, and the linear guide rail guides the clamping device to move forward and backward. That is, to remove the molded product.

[0057] The molding method of the multi-layer continuous co-extrusion hollow machine of the present invention, using the multi-layer continuous co-extrusion hollow machine of Example 6, is implemented according to the following steps: Plastic raw material enters the extrusion device inlet 4021 from the feeding device 13, and is heated to a molten state by multiple sets of energy-saving heaters 401 in the barrel 402. The energy-saving motor 406 drives the feeding screw 403 to rotate at a set speed, stably conveying the molten raw material to the three inlets of the multi-layer electronically controlled die head 6. After entering the multi-layer electronically controlled die head 6, the melt is distributed and compounded into a three-layer plastic melt structure by the flow channel system, and then continues to flow downward, being extruded through the annular gap between the core mold 607 and the die 606 to form a uniformly thick annular preform. During this process, the electric cylinder 602 drives the core mold 607 to reciprocate to control the uniform thickness of the preform. When the preform length reaches the preset value, the robotic arm of the clamping and cutting device 702 quickly clamps the preform and completes the cutting. Servo motor 701 drives clamping and cutting device 702 to descend, precisely feeding the complete blank into the product mold of mold closing mechanism 8. Simultaneously, the bottom of the blank is fitted onto the blow head of blown head device 10. Mold closing mechanism 8 quickly closes the mold via locking cylinder, and blown head device 10 then introduces high-pressure gas, causing the blank to expand and form within the mold. Vertical conveying and cutting mechanism 7 rises and resets, and the clamping device of robot arm 9 advances to clamp the bottom of the hollow product. After mold closing mechanism 8 opens, robot arm 9 removes the blown hollow product from the mold. Finally, the clamping device releases, completing the entire production cycle and obtaining a multi-layered hollow product with uniform wall thickness distribution.

[0058] The advantages of this invention are: It has achieved fully automated production from plastic chemical raw materials to product molding, and can complete continuous co-extrusion blow molding of 100-160 liter three-layer hollow products. The products produced can meet the packaging requirements of food, medicine, electronic chemicals, etc., as well as the packaging requirements of adding PCR raw materials (post-consumer recycled plastics), which greatly satisfies the multi-performance requirements of the products.

[0059] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A multi-layer continuous co-extrusion hollow extruder, characterized in that, The upper platform (1) is fixed to the bottom of the upper platform (1) and a lower frame (2) is fixed to the bottom of the upper platform (1). A multi-layer electric control head (6) is vertically installed on the upper platform (1). The upper platform (1) is equipped with three sets of horizontally arranged extrusion devices: inner layer, middle layer, and outer layer. The discharge ports of the three sets of extrusion devices are connected to the multi-layer electric control head (6). The feed port of the extrusion device is equipped with a feeding device (13). A vertical conveying and cutting mechanism (7) that cooperates with the multi-layer electric control head (6) is fixed to the bottom of the upper platform (1). A mold closing mechanism (8) is set below the vertical conveying and cutting mechanism (7). A blower (10) is installed on the mold closing mechanism (8). A robot arm (9) is fixed to the bottom of the vertical conveying and cutting mechanism (7).

2. The multi-layer continuous co-extrusion hollow extruder according to claim 1, characterized in that, The barrel axes of the inner extrusion device (3) and the outer extrusion device (5) are symmetrically distributed at an angle in the same plane, the middle extrusion device (4) is located between the two, and the mold closing mechanism (8) has a mold opening and closing direction parallel to the barrel axis of the middle extrusion device (4).

3. The multi-layer continuous co-extrusion hollow extruder according to claim 1, characterized in that, The lower frame (2) is a high-rigidity frame structure formed by connecting four vertical columns and horizontal and longitudinal cross braces with high-strength bolts. The upper platform (1) is surrounded by guardrails.

4. The multi-layer continuous co-extrusion hollow extruder according to claim 1, characterized in that, A safety pedal (12) is installed on one side of the upper platform (1), and a protective device (11) is provided on the outside of the mold closing mechanism (8).

5. The multi-layer continuous co-extrusion hollow extruder according to claim 1, characterized in that, The multi-layer electric control head (6) includes an integrated first servo motor (601) and an electric cylinder (602). The main body of the electric cylinder (602) is a planetary roller screw pair. The output shaft of the electric cylinder (602) is connected to a mandrel (604) through a flange (603). The end of the mandrel (604) is connected to a mandrel mold (607). The mandrel mold (607) is fitted with a die (606). The cylinder body (605) of the electric cylinder (602) is connected to the upper platform (1) through adjustable support bolts (608). The cylinder body (605) is provided with three independent feed ports every 90° along the circumference. The three independent feed ports are connected to the discharge ports of the three extrusion devices through transition sections with flanges at both ends.

6. The multi-layer continuous co-extrusion hollow extruder according to claim 1, characterized in that, The extrusion device includes a barrel (402), a feeding screw (403) installed inside the barrel (402), a gearbox (404) connected to one end of the feeding screw (403), and an energy-saving motor (406) connected to the input end of the gearbox (404) via a coupling (405); a multi-component zone temperature-controlled energy-saving heater (401) is arranged on the outer wall of the barrel (402), and a barrel inlet (4021) and a circulating water cooling device (4022) welded to the barrel (402) to form an annular closed cavity are also provided on the barrel (402); the feeding screw diameter and energy-saving motor power specifications of the inner layer, outer layer and middle layer extrusion devices are different.

7. The multi-layer continuous co-extrusion hollow extruder according to claim 1, characterized in that, The mold closing mechanism (8) includes a base (807), on which a parallel linear guide rail (810) is provided. A left template (801), a middle template (803), a synchronization mechanism (806), and a right pull arm (804) are slidably installed from left to right on the linear guide rail (810). A pull rod (802) is passed between the ends of the left template (801) and the right pull arm (804) on the same side. The two pull rods (802) are arranged in parallel. A mold locking cylinder (805) is fixedly connected to the center of the right pull arm (804). The output end of the mold locking cylinder (805) is connected to the middle template (803). The synchronizing mechanism (806) includes a gear and two racks. The racks are distributed on the left and right sides of the gear in a central distribution. The end of one rack is connected to the bottom of the middle template (803), and the end of the other rack is connected to the right pull arm (804). The gear is provided with a housing. A drive motor (808) is fixedly connected to the base (807), and a trapezoidal lead screw assembly (809) is connected to the output end of the drive motor (808). The lead screw nut of the trapezoidal lead screw assembly (809) is fixedly connected to the housing of the synchronization mechanism (806).

8. The multi-layer continuous co-extrusion hollow extruder according to claim 7, characterized in that, The inflation device (10) is connected to the base (807) and located directly below the multi-layer electric control head (6), and on the center line between the left template (801) and the middle template (803). The inflation head of the inflation device (10) is a telescopic structure.

9. The multi-layer continuous co-extrusion hollow extruder according to claim 1, characterized in that, The vertical conveying and cutting mechanism (7) includes a mounting frame (703) that is vertically fixed to the upper platform (1). The mounting frame (703) is provided with a vertical guide rail, and a vertical conveying device (704) is installed in the vertical guide rail. A second servo motor (701) is installed at the top of the mounting frame (703), and the second servo motor (701) drives the vertical conveying device (704) to move vertically up and down. A clamping and cutting device (702) is installed on the vertical conveying device (704) for clamping, releasing and cutting materials. The clamping and cutting device (702) is located directly below the multi-layer electric control head (6). The robotic arm (9) is fixed to the bottom of the mounting frame (703) by a positioning bracket, and the robotic arm (9) is set in parallel with the clamping and cutting device (702).

10. The molding method of a multi-layer continuous co-extrusion hollow extruder as described in any one of claims 1-9, characterized in that, Includes the following steps: The raw material enters the extrusion device through the feeding device (13) to melt, and is then transported by the extrusion device to the multi-layer electric control die head (6) to be compounded into a three-layer melt. The melt is extruded to form a preform and the wall thickness is adjusted. After the preform meets the standard, it is clamped and cut by the vertical conveying and cutting mechanism (7), and then vertically conveyed into the mold closing mechanism (8). The bottom of the preform is fitted with an inflation head. After the mold is closed, the inflation device (10) inflates and forms the preform. The vertical conveying and cutting mechanism (7) rises and resets. The robot (9) moves forward to clamp the bottom of the hollow product. After the mold closing mechanism (8) opens the mold, the robot (9) removes the blown hollow product from the mold and releases it, thus removing the product.

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