A waste material secondary molding process for foam molding of plastic products

Abstract

This invention relates to the field of plastic molding technology and discloses a waste material secondary molding process for foam molding of plastic products. The process includes S1, selecting thermoplastic resin raw materials, mixing them with a foaming agent and a basic nucleating agent according to a preset ratio, and then sending the mixture into a hot air circulating drying oven to control the moisture content of the raw materials and avoid bubble defects in subsequent molding; S2, sending the pretreated raw materials into an injection molding module and plasticizing them using a segmented temperature control mode. This waste material secondary molding process for foam molding of plastic products effectively solves the problem in the prior art where, during the foam molding of plastic products, after the raw materials are plasticized by the injection molding machine and extruded into the mold cavity, and after solidification and shaping, the mold is opened to remove the part, inevitably resulting in parting lines at the mold closing surface. Currently, most of the equipment used in the industry for trimming and edge trimming is only suitable for perfectly round products, with poor adaptability, and cannot trim the contours of quadrilateral plastic products, easily leading to missed or excessive trimming at corners.

Description

Technical Field

[0001] This invention relates to the field of plastic molding technology, and more specifically to a waste material secondary molding process for foam molding of plastic products. Background Technology

[0002] Thermoplastic resin foamed plastic products are widely used in many fields due to their excellent properties such as lightweight, sound insulation, and heat insulation. However, during the foaming process, excess scrap material is generated at the parting line of the product. If this scrap material is discarded directly, it will not only cause serious waste of resources but also lead to environmental pollution. Recycling this scrap material and pre-treating it through crushing and washing to transform it into raw materials that can meet the requirements of foaming molding is one of the core links in realizing the recycling of plastic resources.

[0003] When plastic products are foamed and molded, the raw material is plasticized by an injection molding machine and extruded into the mold cavity. After solidification and shaping, the mold is opened and the part is removed. The mold parting surface will inevitably form parting lines. However, most of the equipment used in the current industry for trimming and edge trimming is only suitable for round products, which has poor adaptability and cannot trim the contours of quadrilateral plastic products. The corners are prone to omissions or over-trimming. Therefore, this application provides a waste material secondary molding process for plastic product foaming and molding, which can efficiently combine injection molding and edge trimming. While completing the foaming and molding of plastic products, the parting lines of the molded products are precisely trimmed at the same time, and the trimming waste is collected for secondary molding, thereby realizing the recycling of waste plastics. Summary of the Invention

[0004] Technical problems to be solved To address the aforementioned shortcomings of existing technologies, this invention provides a waste material secondary molding process for foamed plastic products. This process effectively solves the problem that in existing technologies, during foamed plastic product molding, after the raw material is plasticized by an injection molding machine and extruded into the mold cavity, and after solidification and shaping, the mold is opened to remove the part. Parting lines inevitably form at the mold parting surface. Currently, most equipment used in the industry for trimming and edge trimming is only suitable for perfectly round products, lacking adaptability and unable to trim the contours of quadrilateral plastic products, leading to problems of missed or excessive trimming at corners. Therefore, this invention provides a waste material secondary molding process for foamed plastic products that efficiently combines injection molding and trimming. It simultaneously completes the foaming and molding of the plastic product while simultaneously and precisely trimming the parting lines of the molded product, collecting the trimming waste for secondary molding, thus achieving the recycling of waste plastic.

[0005] Technical solution To achieve the above objectives, the present invention provides the following technical solution: This invention provides a waste material secondary molding process for foam molding of plastic products, comprising: S1. Select thermoplastic resin raw materials, add foaming agent and basic nucleating agent, mix evenly according to the preset ratio, and send them into a hot air circulating drying oven to control the moisture content of the raw materials and avoid bubble defects in subsequent molding. S2. The pretreated raw material is fed into the injection molding module and plasticized using a segmented temperature control mode to complete cell nucleation and initial growth. S3. The foamed melt is rapidly cooled by a cooling system to solidify and lock the cell structure. After shaping, a preliminary foamed product is obtained, ensuring that the shape and size of the product meet the preset requirements. S4. The shaped product is sent to the cutting and trimming machine to trim the parting line of the finished product. The waste generated from the trimming is collected, crushed, and sent back to the injection molding module to achieve secondary molding. The injection molding module in S2 includes a base, an injection mold is mounted on the upper surface of the base, and an extrusion mechanism is fixedly mounted on the outer side of the injection mold and the base. The cutting and trimming machine in S4 includes a positioning part, which includes a movable seat slidably connected to the upper surface of the base. The movable seat is slidably connected to a movable frame via a drive slide rail on its outer surface. The movable frame has an edging structure inside, which includes a connecting block slidably connected to the outer surface of the movable seat. A connecting rod is slidably connected inside the connecting block. A central rod is fixedly connected to the outer end of the connecting rod. A rotating rod is rotatably connected to the outer circumference of the central rod. An angle locking element is provided on the outer surface of the rotating rod. An edge trimmer for removing parting lines is provided in the rotating rod through a through hole. The trimmer includes a trimming head, and a slidable shank is fixedly connected to the side of the trimming head near the connecting rod. A spring connected to the inside of the through hole is sleeved on the outer surface of the slid.

[0006] Furthermore, the movable seat includes front and rear seats and left and right seats, with two of each type. The front and rear seats and left and right seats are vertically distributed and staggered in the vertical direction. Two rotating rods are provided, symmetrically distributed on both sides of the central rod. The drive slide rails on the front and rear seats are formed on their lower surfaces, and the drive slide rails on the left and right seats are formed on their upper surfaces. Each of the front and rear seats and left and right seats has a movable frame slidably connected to its outer surface.

[0007] Furthermore, a torsion spring connected to the interior of the rotating rod is fitted onto the outer circumference of the central rod. A side rod is fixedly connected to the end of the rotating rod away from the central rod. Rollers that fit against the outer surface of the rotating rod are fitted onto the outer circumference of both the side rod and the central rod. The outer circumference of the rollers is covered with a layer of soft elastic material. Under the action of the torsion spring, the rotating rod and its outer side rod are positioned towards the lifting platform. The two rotating rods form an angle of less than 180 degrees on the side away from the connecting rod. Both ends of the central rod and the side rod penetrate through both sides of the rotating rod, and rollers are provided on both the upper and lower sides of the rotating rod.

[0008] Furthermore, a limiting block is fixedly connected to the end of the connecting rod away from the central rod, and a tension spring connected to the outer surface of the connecting block is provided on the outer surface of the limiting block.

[0009] Furthermore, the angle locking component includes an arc-shaped rod fixedly connected to the outer surface of the rotating rod. The connecting rod has an arc-shaped groove inside that fits with the outer surface of the arc-shaped rod. The connecting rod also has a slot inside that communicates with the inside of the arc-shaped groove. A locking block slides inside the slot. A sliding rod is slidably connected inside the connecting rod. The outer end of the sliding rod passes through the side surface of the connecting rod and is fixedly connected to a connecting plate. The outer surface of the connecting plate is fixedly connected to the outer end of the locking block. The outer surface of the locking block is made of silicone material that fits with the arc-shaped outer surface of the arc-shaped rod.

[0010] Furthermore, the inner wall surface of the movable frame is fixedly connected with a pressing block parallel to the outer surface of the connecting plate, the side of the connecting plate near the slide rod is magnetically designed, and the outer side of the connecting rod is magnetically designed to repel the magnetism of the inner surface of the connecting plate.

[0011] Furthermore, the upper surface of the connecting block has a connecting hole, and a conversion block is slidably connected inside the moving frame. The lower surface of the conversion block penetrates the inner surface of the moving frame, and the conversion block engages with the inside of the moving frame through a groove on its outer surface. The outer surface of the conversion block has two sets of grooves, upper and lower. The moving frame is controlled by a drive slide rail to move, and the length of the connecting block is less than the distance between the inner walls of the moving frame. After multiple rollers have contacted the outer edge of the product, when the moving frame moves backward, the inner wall of the moving frame contacts the front side of the connecting block. Correspondingly, the pressing block near the front of the inner wall of the moving frame presses the outer surface of the connecting plate, causing the locking block to embed into the slot. The concave surface of its silicone is tightly fitted with the outer surface of the arc rod inside the arc groove. Through friction, the arc rod near the rear side is fixed to the connecting rod. Thus, when the entire tracing structure moves backward, the position of the rotating rod, side rod, and rollers located at the rear always remains at the slope of the initial contact position.

[0012] Furthermore, the trimming blade has cutting edges on both sides.

[0013] Furthermore, a lifting platform is provided inside the base near the movable seat, and an adsorption hole is provided on the upper surface of the lifting platform. A collection groove is provided on the upper surface of the base. A circulating material bin is provided above the extrusion mechanism and is fixedly connected to the upper surface of the base. A negative pressure suction pipe connected to the inside of the collection groove is fixedly installed on the side of the base, and the end of the negative pressure suction pipe away from the collection groove is connected to the inside of the circulating material bin.

[0014] Beneficial effects The technical solution provided by this invention has the following advantages compared with the prior art: 1. This invention is equipped with a movable seat, a movable frame, an edging structure, and an angle locking component. The movable seat adopts a structure in which the front and rear seats and the left and right seats are vertically staggered, which can accurately cover the four sides of a quadrilateral product. In conjunction with the torsion spring driven rotating rod and three sets of rollers in the edging structure, it can adaptively fit different contours such as straight edges, right angles, and arc angles. By changing the matching relationship between the conversion block and the connecting hole, it can achieve edge trimming of quadrilateral and arc-shaped plastic products without changing equipment or making major structural adjustments. Its adaptability is significantly better than that of existing single-purpose equipment.

[0015] 2. In the tracing structure, the rollers of the side rod and the center rod form a three-point contact positioning. The angle locking component locks the angle of the rotating rod through a high-friction contact between a silicone material block and the arc-shaped rod. This ensures the straightness of the side cutting during trimming and avoids corner offset. Taking the trimming of the right parting line of the finished product as an example, when sliding backward: When trimming right-angle corners, the angle of the rotating rod closer to the feed direction is fixed to avoid over-cutting at the corner due to the influence of the torsion spring; when trimming curved corners, the angle of the rotating rod closer to the feed direction is fixed, while the angle of the rotating rod farther from the feed direction can be tangent to the curved corner under the action of the torsion spring, ensuring that the cutting trajectory of the trimming cutter head accurately matches the contour of the product.

[0016] 3. When applying the outline structure to quadrilateral plastic products, it can perfectly fit not only the sides of the plastic product parallel to the moving base, but also the sides of the plastic product forming an inclined angle with the outer surface of the moving base, making it widely applicable. Furthermore, thanks to the adaptive fitting design of the outline structure, there is no need for precise calibration of the placement position of the quadrilateral plastic product during loading, further reducing operational difficulty. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0018] Figure 1 This is a flowchart of the secondary molding process for plastic product waste according to an embodiment of the present invention; Figure 2 This is a three-dimensional structural schematic diagram of an embodiment of the present invention; Figure 3 This is a cross-sectional structural diagram of the base, collection tank, and negative pressure suction pipe in an embodiment of the present invention; Figure 4 This is a top view of the positioning unit and the lifting platform according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the positioning part according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the tracing structure and trimming head according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the separation structure of the outline structure in an embodiment of the present invention; Figure 8 This is a schematic cross-sectional view of the arc-shaped rod according to an embodiment of the present invention; Figure 9 This is an embodiment of the present invention. Figure 8 A magnified view of a section at point A in the middle; Figure 10 This is a cross-sectional structural diagram of the trimmer and rotating rod according to an embodiment of the present invention; Figure 11 This is a cross-sectional structural diagram of the moving frame, connecting block, and conversion block according to an embodiment of the present invention; Figure 12 This is a schematic diagram of the structure of the moving frame, the conversion block, and the connecting plate according to an embodiment of the present invention; Figure 13 This is a schematic diagram illustrating the state transition of the roller and trimming cutter at the arc corner in an embodiment of the present invention.

[0019] The labels in the diagram represent: 1. Base; 11. Injection mold; 12. Extrusion mechanism; 13. Lifting platform; 14. Collection tank; 15. Circulating hopper; 16. Negative pressure suction pipe; 2. Positioning part; 21. Moving seat; 210. Drive slide rail; 211. Front and rear seats; 212. Left and right seats; 22. Moving frame; 23. Outlining structure; 231. Connecting block; 2311. Connecting hole; 232. Connecting rod; 233. 1. Center rod; 234. Rotating rod; 235. Torsion spring; 236. Side rod; 237. Roller; 238. Limiting block; 239. Tension spring; 24. Angle locking component; 241. Arc rod; 242. Locking block; 2321. Arc groove; 2322. Locking groove; 243. Slide rod; 244. Connecting plate; 245. Pressing block; 25. Conversion block; 3. Trimming tool; 31. Trimming cutter head; 32. Cutting bar; 33. Spring. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] The present invention will be further described below with reference to embodiments.

[0022] Example: Please see Figures 1-13 This invention provides a waste material secondary molding process for foam molding of plastic products, comprising: S1. Select thermoplastic resin raw materials, add foaming agent and basic nucleating agent, mix evenly according to the preset ratio, and send them into a hot air circulating drying oven to control the moisture content of the raw materials and avoid bubble defects in subsequent molding. S2. The pretreated raw material is fed into the injection molding module and plasticized using a segmented temperature control mode to complete cell nucleation and initial growth. S3. The foamed melt is rapidly cooled by a cooling system to solidify and lock the cell structure. After shaping, a preliminary foamed product is obtained, ensuring that the shape and size of the product meet the preset requirements. S4. The shaped product is sent to the cutting and trimming machine to trim the parting line of the finished product. The waste generated from the trimming is collected, crushed, and sent back to the injection molding module to achieve secondary molding. Among them, the injection molding module in S2 includes a base 1, an injection mold 11 is installed on the upper surface of the base 1, and an extrusion mechanism 12 is provided on the outside of the injection mold 11 and fixedly installed on the upper surface of the base 1. The S4 trimming and edge-trimming machine includes a positioning unit 2, which includes a movable seat 21 slidably connected to the upper surface of the base 1. The movable seat 21 is slidably connected to a movable frame 22 via a drive slide rail 210 on its outer surface. The movable frame 22 has an edging structure 23 inside, which includes a connecting block 231 slidably connected to the outer surface of the movable seat 21. A connecting rod 232 is slidably connected inside the connecting block 231. A central rod 233 is fixedly connected to the outer end of the connecting rod 232. A rotating rod 234 is rotatably connected to the outer circumference of the central rod 233. An angle locking member 24 is provided on the outer surface of the rotating rod 234. An edge trimmer 3 for removing parting lines is provided in the rotating rod 234 through a through hole. The movable seat 21 is driven to slide by a drive motor inside the base 1. The trimmer 3 includes a trimming head 31. A knife bar 32 that is slidably connected in the through hole is fixedly connected to the side of the trimming head 31 near the connecting rod 232. A spring 33 connected to the inside of the through hole is sleeved on the outer surface of the knife bar 32.

[0023] The movable seat 21 includes front and rear seats 211 and left and right seats 212, with two of each. The front and rear seats 211 and left and right seats 212 are vertically distributed, and their vertical arrangement is staggered. Two rotating rods 234 are provided, symmetrically distributed on both sides of the central rod 233. Drive rails 210 on the lower surface of the front and rear seats 211 and on the upper surface of the left and right seats 212 are provided. Each of the front and rear seats 211 and left and right seats 212 has a sliding frame 22 slidably connected to its outer surface. Initially, all four movable seats 21 are located away from the lifting platform 13. Under the action of the tension spring 239, the central rod 233 protrudes towards the lifting platform 13, at which point the distance between the central rod 233 and the connecting block 231 is at its maximum.

[0024] A torsion spring 235, which is connected to the inside of the rotating rod 234, is fitted on the outer circumference of the central rod 233. A side rod 236 is fixedly connected to the end of the rotating rod 234 away from the central rod 233. Rollers 237, which are in contact with the outer surface of the rotating rod 234, are fitted on the outer circumference of both the side rod 236 and the central rod 233. The outer circumference of the rollers 237 is covered with a soft elastic material layer. Under the action of the torsion spring 235, the rotating rod 234 and the side rod 236 at its outer end are positioned towards the lifting platform 13. The two rotating rods 234 form an angle of 90-120 degrees on the side away from the connecting rod 232. Both ends of the central rod 233 and the side rod 236 pass through both sides of the rotating rod 234. Rollers 237 are provided on both the upper and lower sides of the rotating rod 234.

[0025] A limit block 238 is fixedly connected to one end of the connecting rod 232 away from the center rod 233, and a tension spring 239 connected to the outer surface of the connecting block 231 is provided on the outer surface of the limit block 238.

[0026] The angle locking component 24 includes an arc-shaped rod 241 fixedly connected to the outer surface of the rotating rod 234. The connecting rod 232 has an arc-shaped groove 2321 inside that fits with the outer surface of the arc-shaped rod 241. The connecting rod 232 has a slot 2322 inside that communicates with the inside of the arc-shaped groove 2321. A locking block 242 slides inside the slot 2322. A sliding rod 243 is slidably connected inside the connecting rod 232. The outer end of the sliding rod 243 passes through the side surface of the connecting rod 232 and is fixedly connected to a connecting plate 244. The outer surface of the connecting plate 244 is fixedly connected to the outer end of the locking block 242. The outer surface of the locking block 242 is made of silicone material that fits with the arc-shaped outer surface of the arc-shaped rod 241.

[0027] The inner wall surface of the movable frame 22 is fixedly connected with a pressing block 245 parallel to the outer surface of the connecting plate 244. The side of the connecting plate 244 near the slide rod 243 is magnetically designed, and the outer side of the connecting rod 232 is magnetically designed to repel the magnetism of the inner surface of the connecting plate 244.

[0028] The upper surface of the connecting block 231 has a connecting hole 2311. The inside of the moving frame 22 is slidably connected to the conversion block 25. The lower surface of the conversion block 25 penetrates the inner surface of the moving frame 22. The conversion block 25 is engaged with the inside of the moving frame 22 through a groove on its outer surface. The outer surface of the conversion block 25 has two sets of grooves, upper and lower.

[0029] The trimming cutter head 31 has cutting edges on both sides.

[0030] A lifting platform 13 is located inside the base 1, near the movable seat 21. The upper surface of the lifting platform 13 has suction holes, and a collection trough 14 is located on the upper surface of the base 1. A circulating material hopper 15 is fixedly connected to the upper surface of the base 1 above the extrusion mechanism 12. A negative pressure suction pipe 16, communicating with the inside of the collection trough 14, is fixedly installed on the side of the base 1. The end of the negative pressure suction pipe 16 away from the collection trough 14 is connected to the inside of the circulating material hopper 15. The collection trough 14 is located on the outer periphery of the lifting platform 13, and the outer edge of the lifting platform 13 is angled. The inner wall of the collection trough 14 is inclined to facilitate the falling of the parting line. Two symmetrically distributed crushing rollers are arranged inside the collection trough 14.

[0031] In the initial state, all four movable seats 21 are at their extreme positions far from the lifting platform 13. Simultaneously, the movable frame 22 is located in the middle of the drive slide rail 210, with a pre-reserved gap between the inner wall of the movable frame 22 and the connecting block 231. The tension spring 239 is in a stretched state, pulling the connecting rod 232 through the limiting block 238, causing the connecting rod 232 and its outer end's central rod 233 to protrude towards one side of the lifting platform 13. At this time, the distance between the central rod 233 and the connecting block 231 is at its maximum. The torsion spring 235 drives the two rotating rods 234 to maintain an angle of 90-120 degrees on the side closest to the lifting platform 13. The rollers 237 are in an open state, with the distance from the roller 237 located on the outer circumference of the side rod 236 to the lifting platform 13 being less than the distance from the roller 237 located on the outer circumference of the central rod 233 to the lifting platform 13. In the angle locking component 24, the locking block 242 is not fully embedded in the slot 2322, and the silicone concave arc surface of its outer surface does not contact the outer surface of the arc-shaped rod 241. The connecting plate 244 maintains a distance from the connecting rod 232 under magnetic repulsion, and the pressing block 245 separates from the connecting plate 244. In the trimmer 3, the spring 33 is in a balanced state, and the two cutting edges of the trimming cutter head 31 face the directions of the corresponding side rod 236 and the center rod 233, respectively. Under the action of the lifting platform 13, the center height of the cutting edge of the trimming cutter head 31 is the same as the height of the finished product parting line.

[0032] The process of one-time foaming molding: The extrusion mechanism 12 includes a hopper, a screw, and a barrel. Pre-treated raw materials are fed into the hopper and enter the barrel. A segmented temperature control mode is used to heat the barrel (lower temperature in the feeding section, highest temperature in the plasticizing section, and the temperature at the die head meets the melt flow characteristics), gradually plasticizing the raw material into a molten state. After plasticizing, pressure is applied by the screw of the extrusion mechanism 12, forcing the melt through the die head into the injection mold 11. The melt completes cell nucleation and initial growth within the mold cavity. Then, the cooling system outside the injection mold 11 is activated, rapidly cooling the foamed melt within the mold cavity through cooling water circulation, solidifying the melt and locking the cell structure. Once the mold temperature drops to the preset range, the injection mold 11 is opened.

[0033] The adsorption and fixation process of plastic products: An external robotic arm removes the pre-formed quadrilateral product (with parting lines) and places it stably on the upper surface of the lifting platform 13, aligning the center of the plastic product with the center of the lifting platform 13, with the parting lines on each of the four sides facing one side of the four movable seats 21. An external vacuum pump is activated, generating negative pressure in the suction holes, which acts on the bottom of the plastic product through the air channels, firmly adsorbing and fixing the product onto the lifting platform 13 to prevent displacement during the trimming process.

[0034] The process of outlining structure 23 as it approaches the side contour of the plastic product: The servo drive motor built into the base 1 is activated, driving the four movable seats 21 to slide simultaneously toward the lifting platform 13 according to the size of the plastic product: the front and rear seats 211 slide along the length of the base 1, and the left and right seats 212 slide along the width of the base 1. This continues until the moving frame 22 moves the stroking structure 23 close to the four sides of the plastic product.

[0035] When the plastic product is a quadrilateral product, taking the left and right seats 212 on the right side as an example, initially, the moving frame 22 is in the middle of the drive slide rail 210, that is, the moving frame 22 coincides with the center of the plastic product in the length direction. The left and right seats 212 on the right side slide to the left (i.e., close to the lifting platform 13) under the drive of the servo drive motor built into the base 1. The moving frame 22 and the stroking structure 23 that slide on the upper surface of the left and right seats 212 move to the left in sync. During this process, the roller 237 fitted on the outer circumference of the side rod 236 in the stroking structure 23 first comes into contact with the right side of the plastic product. As the moving seat 21 continues to slide, the plastic product generates a reverse resisting force on the outer roller 237 of the side rod 236. This force is transmitted to the rotating rod 234 through the side rod 236, driving the two rotating rods 234 to rotate synchronously around the axis of the central rod 233 in a direction away from the lifting platform 13. The torsion spring 235, which was originally in a state of natural compression, is further compressed by the pressure of the rotating rod 234, and its elastic potential energy gradually accumulates. Meanwhile, the continuous sliding of the movable seat 21 gradually reduces the horizontal distance between the axis of the central rod 233 and the right side of the plastic product, and the tension spring 239 is gradually compressed until the roller 237 sleeved on the outer circumference of the central rod 233 is in complete contact with the right side of the plastic product. At this time, the outer rollers 237 of the side rods 236 and the outer rollers 237 of the central rod 233 are in surface contact with the side of the product, and the axis of the two side rods 236 and the central rod 233 are in the same vertical plane. The included angle between the two rotating rods 234 increases to 180 degrees. The rollers 237 on the outer circumference of the central rod 233 and the rollers 237 on the outer circumference of the two sets of side rods 236 are in close contact with the planar contour of the plastic product, achieving the initial fitting and positioning of the side contour.

[0036] During the rotation of the rotating rod 234 around the axis of the central rod 233, since the locking block 242 is not fully embedded in the slot 2322, the arc-shaped rod 241, which is fixedly connected to the outer surface of the rotating rod 234, will slide smoothly inside the arc-shaped slot 2321. Since the outer surface of the trimming cutter head 31 is parallel to the outer surface of the rotating rod 234, as the rotating rod 234 changes from being inclined to the right side of the plastic product to being parallel, the outer surface of the trimming cutter head 31 also changes from being inclined to the right side of the plastic product to being in contact with it. During this posture change, the cutting edge of the trimming cutter head 31 first cuts into the redundant material of the parting line at a preset angle with the parting line. As the rotation angle of the rotating rod 234 is continuously adjusted, the cutting depth of the cutting edge gradually becomes uniform. Finally, the cutting edge plane of the trimming cutter head 31 is completely perpendicular to the extension direction of the parting line, realizing the full length of the cutting edge in contact with the parting line, laying the foundation for subsequent stable cutting.

[0037] If the right side of the plastic product is parallel to the left and right seats 212, then the rotating rod 234 and the connecting rod 232 are perpendicular to each other. If the right side of the plastic product is tilted and not parallel to the outer surface of the left and right seats 212, then the rotating rod 234 and the connecting rod 232 will form an angle that is not ninety degrees, but the axis lines of the two side rods 236 and the central rod 233 are still in the same plane. The positioning process of the other three moving seats 21 driving the corresponding outlining structure 23 is consistent with that of the right left and right seats 212, and finally the contour positioning of the four sides is achieved.

[0038] The process of locking the 234 angle of the swivel rod: Continuing with the example of the right side left and right seats 212, after positioning, the drive slide rail 210 is activated, controlling the moving frame 22 to slide along the drive slide rail 210 of the right side left and right seats 212, causing the stroking structure 23 to slide in the front and back direction. When the moving frame 22 moves backward, the inner wall surface of the moving frame 22 will contact the front side of the connecting block 231, causing the connecting block 231 to move backward as well (the connecting block 231 slides with the outer surface of the moving seat 21, resulting in greater friction). During this process, the pressing block 245 on the front side of the moving frame 22 moves backward synchronously and presses against the connecting plate 244 on the front side of the connecting rod 232 (corresponding to the connecting plate 244 on the front side of the connecting rod 232 and the rotating rod 234 and the arc rod 241 on the rear side in the left and right seats 212 located on the right). When the pressing force is greater than the repulsive magnetic force between the connecting plate 244 and the connecting rod 232, the connecting plate 244 will drive the sliding rod 243 and the locking block 242 to move synchronously towards the connecting rod 232 (rear side).

[0039] The connecting plate 244 drives the sliding rod 243 to slide along the guide hole of the connecting rod 232, while simultaneously pushing the locking block 242 to move along the slot 2322 towards the arc-shaped groove 2321. Finally, the concave silicone surface of the locking block 242 is embedded into the slot 2322 and tightly adheres to the outer surface of the arc-shaped rod 241 in the arc-shaped groove 2321. The high friction of the silicone material is used to fix the arc-shaped rod 241 to the connecting rod 232. At this time, the angle of the rotating rod 234 near the rear is locked.

[0040] The process of trimming and removing excess parting lines: The control drive slide rail 210 drives the moving frame 22 to continue retracting (away from the plastic product). The inner wall of the moving frame 22 contacts the front side of the connecting block 231 and pushes the connecting block 231 to retract synchronously. Because the angle of the rotating rod 234 near the rear is locked, the trimming cutter head 31 remains in contact with the right side of the plastic product, ensuring that the trimming cutter head 31 cuts in a straight line during subsequent trimming. Depending on the type of edge of the plastic product, the trimming process is divided into the following two cases: When the corners of the quadrilateral plastic product are rounded, the tracing structure 23 moves backward under the drive of the moving frame 22. A set of rollers 237 near the rear side completely passes through the side and moves to the outside of the plastic product. During this process, the rotating rod 234 near the rear side and its internal trimming cutter 31 always slide in contact with the right side surface to complete the trimming of the straight edge. When the roller 237 on the outer surface of the central rod 233 reaches the corner of the arc, the connecting rod 232 and the central rod 233, under the action of the tension spring 239, drive the roller 237 on the outer surface of the central rod 233 to slide closely against the arc contour. At this time, the trimming cutter 31 near the front rotating rod 234 trims the parting line of the arc edge, while the trimming cutter 31 near the rear rotating rod 234 is in a suspended state and does not contact the side of the plastic product, thus avoiding the phenomenon of overcutting by the trimming cutter 31 and ensuring the smoothness and accuracy of the arc edge trimming.

[0041] It should be noted that when the trimming cutter head 31, located near the front rotating rod 234, trims the parting line of the arc edge, both the front roller 237 and the outer surface roller 237 of the center rod 233 are in contact with the arc surface, forming a double-point positioning support. The cutting direction of the trimming cutter head 31 is always consistent with the tangent direction of the arc angle, ensuring that the cutting trajectory precisely matches the arc surface contour. During this process, due to the change in the curvature of the arc surface and the fluctuation of the tension of the tension spring 239, the trimming cutter head 31 and the cutter bar 32 will float slightly in the horizontal direction. The spring 33, sleeved on the outer surface of the cutter bar 32, will buffer the floating impact force in real time through its own elastic deformation, while continuously providing a stable preload to the trimming cutter head 31, ensuring that the trimming cutter head 31 always fits the parting line, avoiding surface damage to the product caused by cutting gaps or excessive compression.

[0042] When the corners of the quadrilateral plastic product are right angles, the tracing structure 23 moves backward continuously under the drive of the moving frame 22. First, a set of rollers 237 near the rear side completely passes through the side and moves to the outside of the plastic product. Then, the rollers 237 on the outer surface of the central rod 233 move to the right-angle corner. Throughout this process, the rotating rod 234 near the rear side and its internal trimming cutter 31 always slide in contact with the right side surface, completing the trimming of the straight edge of that side. The rear edge of the trimming cutter 31 continuously cuts the redundant material in the rear half of the right parting line, completing the trimming of the rear half of the straight edge of that side. The cutting waste falls off naturally along the cutting edge, leaving no residual burrs.

[0043] After trimming the rear half of the straight edge on the right side of the plastic product, the moving frame 22 moves, and the drive slide rail 210 drives the moving frame 22 forward in the opposite direction to trim the parting line of the front half of the straight edge on the right side of the plastic product. The waste material generated during the cutting process falls directly into the collection groove 14 on the outer periphery of the lifting platform 13.

[0044] Whether moving forward or backward, two trimming cutters 31 perform the cutting. When moving forward, the front trimming cutter 31 has a primary cutting edge on the front side, emphasizing cutting efficiency and edge smoothness. The rear trimming cutter 31 has a secondary cutting edge on the front side, playing an auxiliary role and emphasizing anti-burr effect. When moving backward, the rear trimming cutter 31 has a primary cutting edge on the rear side, emphasizing cutting efficiency and edge smoothness. The front trimming cutter 31 has a secondary cutting edge on the rear side, playing an auxiliary role and emphasizing anti-burr effect.

[0045] The conversion block 25 is used to change the contact state between the moving frame 22 and the connecting block 231. When processing a quadrilateral plastic product, the conversion block 25 is vertically moved so that one of the grooves on its outer surface engages with the inside of the moving frame 22. At this time, the bottom of the conversion block 25 is not inside the connecting hole 2311, and the moving frame 22 and the connecting block 231 are in a separated state. When the moving frame 22 moves, the angle of one of the rotating rods 234 is locked. When processing arc-shaped plastic products, the conversion block 25 is vertically moved so that another groove on its outer surface engages with the inside of the moving frame 22. At this time, the lower part of the conversion block 25 is completely embedded in the connecting hole 2311, and the moving frame 22 and the connecting block 231 form a whole. The connecting block 231 is fixed in the middle of the moving frame 22. The pressing block 245 on the outer surface of the moving frame 22 does not contact the outer surface of any connecting plate 244. When the moving frame 22 moves, the angle of the rotating rod 234 is not locked. Both rotating rods 234 can rotate. The three sets of rollers 237 can always be in contact with the arc surface of the arc-shaped plastic product under the action of the torsion spring 235 and the tension spring 239. The trimming head 31 in the rotating rod 234 can adjust the cutting angle in real time according to the curvature of different positions.

[0046] During the trimming process, the crushing rollers in the collection trough 14 continuously operate to crush the trimming waste that falls into it. The negative pressure system of the negative pressure suction pipe 16 is activated to suck the crushed waste particles into the circulating hopper 15 for temporary storage.

[0047] After trimming, the vacuum pump is turned off to release the adsorption of the product on the upper surface of the lifting platform 13. The qualified product after trimming is then removed by the robotic arm. The four moving seats 21 are controlled to return to their extreme positions away from the lifting platform 13, and the moving frame 22 is reset to the middle of the drive slide rail 210, restoring the initial state.

[0048] The process of secondary molding of plastic products: The bottom of the circulating hopper 15 is opened, and the pre-treated waste particles are mixed evenly with the new material according to the preset ratio and fed into the hopper of the extrusion mechanism 12. The foaming molding steps in this process are repeated: the extrusion mechanism 12 controls the temperature and plasticizes in stages, extrudes into the injection mold 11 for foaming, cools and shapes, and finally completes the secondary molding of the waste material to achieve resource recycling.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A waste material secondary molding process for foaming and molding plastic products, characterized in that, include: S1. Select thermoplastic resin raw materials, add foaming agent and basic nucleating agent, mix evenly according to the preset ratio, and send them into a hot air circulating drying oven to control the moisture content of the raw materials and avoid bubble defects in subsequent molding. S2. The pretreated raw material is fed into the injection molding module and plasticized using a segmented temperature control mode to complete cell nucleation and initial growth. S3. The foamed melt is rapidly cooled by a cooling system to solidify and lock the cell structure. After shaping, a preliminary foamed product is obtained, ensuring that the shape and size of the product meet the preset requirements. S4. The shaped product is sent to the cutting and trimming machine to trim the parting line of the finished product. The waste generated from the trimming is collected, crushed, and sent back to the injection molding module to achieve secondary molding. The injection molding module in S2 includes a base (1), an injection mold (11) is mounted on the upper surface of the base (1), and an extrusion mechanism (12) is fixedly mounted on the outer side of the injection mold (11) and the upper surface of the base (1). Among them, the cutting and trimming machine in S4 includes a positioning part (2), the positioning part (2) includes a movable seat (21) slidably connected to the upper surface of the base (1), the movable seat (21) is slidably connected to a movable frame (22) via a drive slide rail (210) on its outer surface, the movable frame (22) is provided with an edging structure (23) inside, the edging structure (23) includes a connecting block (231) slidably connected to the outer surface of the movable seat (21), the connecting block (231) is slidably connected to a connecting rod (232), the outer end of the connecting rod (232) is fixedly connected to a central rod (233), the outer circumferential surface of the central rod (233) is rotatably connected to a rotating rod (234), the outer surface of the rotating rod (234) is provided with an angle locking member (24), and the rotating rod (234) is provided with an edge trimmer (3) for removing parting lines through a through hole in its interior. The trimmer (3) includes a trimming head (31), and a knife bar (32) that is slidably connected in the through hole is fixedly connected to the side of the trimming head (31) near the connecting rod (232). A spring (33) connected to the inside of the through hole is sleeved on the outer surface of the knife bar (32). The angle locking component (24) includes an arc-shaped rod (241) fixedly connected to the outer surface of the rotating rod (234). The connecting rod (232) has an arc-shaped groove (2321) that fits against the outer surface of the arc-shaped rod (241). The connecting rod (232) has a slot (2322) that communicates with the inside of the arc-shaped groove (2321). A locking block (242) slides against the inside of the slot (2322). A sliding rod (243) slides against the inside of the connecting rod (232). The outer end of the sliding rod (243) passes through the side surface of the connecting rod (232) and is fixedly connected to a connecting plate (244). The outer surface of the connecting plate (244) is fixedly connected to the outer end of the locking block (242). The outer surface of the locking block (242) is made of silicone material that fits against the arc-shaped outer surface of the arc-shaped rod (241).

2. The waste material secondary molding process for foam molding of plastic products according to claim 1, characterized in that: The movable seat (21) includes a front and rear seat body (211) and a left and right seat body (212). There are two of each of the front and rear seat bodies (211) and the left and right seat bodies (212). The front and rear seat bodies (211) and the left and right seat bodies (212) are vertically distributed, and the front and rear seat bodies (211) and the left and right seat bodies (212) are staggered in the vertical direction. There are two rotating rods (234). The two rotating rods (234) are symmetrically distributed on both sides of the central rod (233).

3. The waste secondary molding process for foam molding of plastic products according to claim 2, characterized in that: The outer circumference of the central rod (233) is fitted with a torsion spring (235) connected to the inside of the rotating rod (234). The end of the rotating rod (234) away from the central rod (233) is fixedly connected with a side rod (236). The outer circumference of both the side rod (236) and the central rod (233) is fitted with rollers (237) that fit against the outer surface of the rotating rod (234). The outer circumference of the rollers (237) is covered with a soft elastic material layer.

4. The waste secondary molding process for foam molding of plastic products according to claim 3, characterized in that: The end of the connecting rod (232) away from the center rod (233) is fixedly connected to a limiting block (238), and the outer surface of the connecting block (231) is provided with a tension spring (239) connected to the outer surface of the limiting block (238).

5. The waste secondary molding process for foam molding of plastic products according to claim 4, characterized in that: The inner wall surface of the movable frame (22) is fixedly connected with a pressing block (245) parallel to the outer surface of the connecting plate (244). The side of the connecting plate (244) near the slide rod (243) is magnetically designed, and the outer side of the connecting rod (232) is magnetically designed to repel the magnetism of the inner surface of the connecting plate (244).

6. The waste secondary molding process for foam molding of plastic products according to claim 5, characterized in that: The upper surface of the connecting block (231) is provided with a connecting hole (2311), and the inside of the moving frame (22) is slidably connected with a conversion block (25). The lower surface of the conversion block (25) penetrates the inner surface of the moving frame (22), and the conversion block (25) is engaged with the inside of the moving frame (22) through a groove on its outer surface.

7. The waste secondary molding process for foam molding of plastic products according to claim 1, characterized in that: The trimming cutter head (31) has cutting edges on both sides.

8. The waste material secondary molding process for foam molding of plastic products according to claim 2, characterized in that: A lifting platform (13) is provided on the side of the base (1) near the moving seat (21). An adsorption hole is provided on the upper surface of the lifting platform (13). A collection groove (14) is provided on the upper surface of the base (1). A circulating hopper (15) is fixedly connected to the upper surface of the base (1) above the extrusion mechanism (12). A negative pressure suction pipe (16) connected to the inside of the collection groove (14) is fixedly installed on the side of the base (1). The end of the negative pressure suction pipe (16) away from the collection groove (14) is connected to the inside of the circulating hopper (15).

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