A continuous melt-compensated plastic rod extrusion apparatus
By using a continuous melt-compensated plastic rod extrusion equipment, the internal defects caused by uneven cooling of large-diameter rods are solved by regulating the melt pressure through a cooling system and a traction machine. This achieves high density and low-cost production and is suitable for stable production of large-diameter rods.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- NINGBO FANGLI TECH
- Filing Date
- 2025-08-26
- Publication Date
- 2026-07-21
AI Technical Summary
During the extrusion process, uneven cooling of large-diameter plastic rods can cause core shrinkage, resulting in shrinkage cavities, air holes, or porosity defects, which affect the density and strength of mechanical structural parts and pipes.
A continuous melt-compensated plastic rod extrusion equipment is adopted. By setting a cooling system and a traction machine in the shaping sleeve to regulate the melt pressure, the melt dynamically compensates and fills the core during the cooling process, forming a gradually shrinking melt compensation zone, ensuring that the melt continuously compensates under the combined action of extrusion pressure and traction resistance.
It effectively prevents internal defects, improves the density and structural uniformity of bars, reduces equipment investment costs, simplifies mold structure and improves process controllability, and is suitable for stable production of large-diameter bars.
Smart Images
Figure CN224527932U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of plastic rod extrusion molding technology, specifically relating to a continuous melt compensation type plastic rod extrusion equipment. Background Technology
[0002] Plastic rods are widely used in the manufacture of mechanical structural parts and plastic pipe system connectors. With the increasing demands for the performance of plastic products in industrial applications, the demand for large-diameter plastic rods is growing. These large rods are usually used to process plastic pipe connectors with high strength and high sealing requirements.
[0003] However, during the extrusion of current plastic rods (especially large-diameter plastic rods with a diameter greater than 630mm), due to the poor thermal conductivity of plastic, the outer layer of the rod solidifies rapidly during the cooling process, while the core cools slowly and shrinks significantly. At this time, the solidified outer layer restricts the free shrinkage of the core, resulting in shrinkage cavities, air holes, or loose defects inside, which seriously affects the overall density of the rod.
[0004] Such internal defects can easily lead to problems such as stress concentration, insufficient strength, and sealing failure when they are subsequently processed into mechanical structural parts or pipe fittings, making it impossible to meet the requirements for high pressure bearing and high sealing performance of the connecting parts. Utility Model Content
[0005] This invention addresses the aforementioned problems in the prior art by proposing a continuous melt-compensated plastic rod extrusion device that can prevent the formation of air holes in the core of plastic rods.
[0006] This utility model can be achieved through the following technical solutions:
[0007] A continuous melt-compensated plastic rod extrusion device includes:
[0008] An extruder, a die, a shaping sleeve, and a traction machine are arranged coaxially along the material extrusion direction. The inner cavity of the die forms a feeding channel, and the inner cavity of the shaping sleeve forms a melt channel. The feeding channel is connected to the melt channel.
[0009] The sizing sleeve is provided with a cooling system on its peripheral wall. The cooling system gradually cools the bar located in the melt channel from the outer wall to the core. As the traction machine continues to pull the bar forward, the bar located at the outlet end of the melt channel cools and solidifies to form a solid part, while the bar located at the inlet end of the melt channel is in a molten state and forms a cone-shaped melt compensation zone.
[0010] The traction speed of the traction machine is less than the extrusion speed of the extruder. The melt located in the melt compensation zone continuously compensates and fills the pre-solidified core of the rod under the combined force of extrusion pressure and traction resistance.
[0011] As a further improvement of this utility model, the diameter of the melt compensation zone gradually decreases along the extrusion direction of the rod and closes at the core of the rod.
[0012] As a further improvement of this utility model, the conical circumferential surface of the melt compensation zone is an inclined surface or an inwardly concave curved surface.
[0013] As a further improvement of this utility model, the shaping sleeve is composed of an inner sleeve and an outer sleeve, and the mating surface of the inner sleeve and the outer sleeve is provided with a cooling channel for the flow of cooling medium to form the cooling system.
[0014] As a further improvement of this utility model, the cross-sectional area of the feed channel gradually increases from its inlet end to its outlet end to form a gradually expanding flow channel.
[0015] As a further improvement of this utility model, the cross-sectional area of the outlet end flow channel of the feed channel is the same as the cross-sectional area of the inlet end flow channel of the melt channel.
[0016] As a further improvement of this utility model, the extrusion end of the extruder is connected to the die via the die head body, and the flow channel cross-sectional area at the inlet end of the die head body is larger than the flow channel cross-sectional area at its outlet end.
[0017] As a further improvement of this utility model, the cross-sectional area of the flow channel at the outlet end of the machine head body is the same as the cross-sectional area of the flow channel at the inlet end of the feed channel.
[0018] As a further improvement of this utility model, a heat insulation pad is provided on the mating surface of the die and the shaping sleeve.
[0019] As a further improvement of this utility model, a spray box is also provided between the shaping sleeve and the traction machine.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] 1. Effectively prevents loose bar structure and improves internal density:
[0022] During the cooling and shaping process of the bar stock, by establishing a collaborative mechanism between the gradient solidification front and the melt compensation zone, the melt continuously compensates and fills the solidifying core under the combined action of extrusion pressure and traction resistance. This process realizes a continuous molding mode of "cooling and feeding at the same time", which fundamentally prevents the problems of internal voids and loose structure caused by cooling shrinkage, and significantly improves the overall density and structural uniformity of the bar stock.
[0023] 2. Smaller-sized extruders can be used to process large-sized bars, reducing equipment investment costs:
[0024] Because the cooling and solidification of large-diameter bars takes a long time, the amount of melt entering the melt channel per unit time is small. Therefore, stable production of large-diameter (e.g., >630mm) bars can be achieved without relying on large, high-power extruders, significantly reducing the demand for high-specification extrusion equipment and saving equipment procurement and operating costs.
[0025] 3. By adjusting the melt pressure through a traction machine, the mold structure is simplified and the process controllability is improved:
[0026] By adjusting the speed of the traction machine to change the traction resistance of the melt, the melt pressure and compensation rate in the shaping zone can be precisely controlled. This pressure control method does not rely on complex flow channel design or in-mold pressure adjustment mechanism, reducing manufacturing difficulty and maintenance costs. At the same time, the traction speed, as an externally adjustable parameter, responds quickly and is easy to operate, facilitating rapid process adjustments according to different materials and specifications, thus improving production flexibility and control accuracy. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the layout of the continuous melt compensation type plastic rod extrusion equipment of this utility model.
[0028] In the diagram, 100 is the extruder; 110 is the die head; 120 is the die; 121 is the feed channel; 130 is the shaping sleeve; 131 is the melt channel; 132 is the inner sleeve; 133 is the outer sleeve; 134 is the cooling channel; 140 is the spray box; 150 is the traction machine; and 160 is the heat insulation pad.
[0029] 200, bar stock; 210, solid section; 220, melt compensation zone. Detailed Implementation
[0030] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. The technical methods of the present invention will be further described, but the present invention is not limited to these embodiments.
[0031] like Figure 1 As shown, this utility model provides a continuous melt-compensated plastic rod extrusion device, comprising:
[0032] An extruder 100, a die 120, a shaping sleeve 130, and a traction machine 150 are arranged coaxially along the material extrusion direction. The inner cavity of the die 120 forms a feeding channel 121, and the inner cavity of the shaping sleeve 130 forms a melt channel 131. The feeding channel 121 is connected to the melt channel 131.
[0033] The circumferential wall of the shaping sleeve 130 is provided with a cooling system, which gradually cools the bar 200 located inside the shaping sleeve 130 from the outer wall to the core.
[0034] Specifically, as the traction machine 150 continues to pull the bar 200 forward, the bar 200 located at the outlet end of the melt channel 131 has been fully cooled and formed a dense solid part 210, while the bar 200 located at the inlet end of the fixed melt channel 131 is still in a high-temperature molten state and has not yet been fully shaped, thus forming a cone-shaped melt compensation zone 220. This melt compensation zone 220 provides the necessary pressure transmission path for subsequent material replenishment.
[0035] Furthermore, the traction speed of the traction machine 150 is less than the extrusion speed of the extruder 100, forming a "slow pull, fast extrusion" operating state. This speed difference causes the melt to generate a combined force that propels it axially toward the core under the combined action of extrusion pressure and traction resistance, driving the melt to continuously flow toward the core area of the solidified rod 200, thereby achieving dynamic and continuous compensation filling of the cooling shrinkage volume.
[0036] In other words, the entire compensation process is equivalent to establishing a "self-compensating" mechanism inside the bar 200, effectively preventing internal voids caused by uneven cooling. The beneficial effects of this include at least the following:
[0037] 1. Effectively avoids loose structure in bar stock 200 and improves internal density.
[0038] During the cooling and shaping process of bar 200, a collaborative mechanism between the gradient solidification front and the melt compensation zone 220 is established, enabling the melt to continuously and dynamically compensate and fill the solidifying core under the combined action of extrusion pressure and traction resistance. This process achieves a continuous molding mode of "cooling and feeding simultaneously," fundamentally preventing internal voids and loose structures caused by cooling shrinkage, and significantly improving the overall density and structural uniformity of bar 200.
[0039] 2. Smaller-sized extruders (e.g., 100mm) can be used to process large-sized bars, reducing equipment investment costs.
[0040] Since the cooling and solidification of large-diameter bars takes a long time, the amount of melt entering the melt channel 131 per unit time is small. Therefore, stable production of large-diameter (e.g., >630mm) bars 200 can be achieved without relying on large, high-power extruders 100, significantly reducing the demand for high-specification extrusion equipment and saving equipment procurement and operating costs.
[0041] 3. By adjusting the melt pressure using the traction machine 150, the mold structure is simplified and the process controllability is improved.
[0042] By adjusting the speed of the traction machine 150, the traction resistance to the melt is changed, thereby precisely controlling the melt pressure and compensation rate in the shaping zone. This pressure control method does not rely on complex flow channel design or in-mold pressure adjustment mechanism, reducing manufacturing difficulty and maintenance costs. At the same time, the traction speed, as an externally adjustable parameter, responds quickly and is easy to operate, facilitating rapid process adjustments according to different materials and specifications, thus improving production flexibility and control accuracy.
[0043] Overall, the solution provided in this embodiment, through an innovative melt continuous compensation mechanism, not only solves the industry problem of core defects easily occurring in large-diameter plastic rods 200, but also achieves multiple technological advancements such as cost reduction of equipment, simplification of molds, and ease of process control while ensuring product quality, and has significant industrial application value.
[0044] Preferably, the diameter of the melt compensation zone 220 gradually decreases along the extrusion direction of the rod 200 and closes at the core of the rod 200. The formation of this cone-shaped melt compensation zone 220 allows the melt to flow smoothly along the gradually narrowing path during its advancement toward the core, avoiding flow turbulence or stagnation. This facilitates the concentrated and continuous injection of the melt into the solidifying core region of the rod 200 under pressure, achieving efficient and uniform volume compensation.
[0045] Meanwhile, the melt compensation zone 220, which is closed at the core of the rod 200, helps to establish a stable solidification front, improves the overall uniformity of the structure and mechanical properties of the rod 200, and is particularly suitable for high-quality continuous production of large-diameter, high-requirement plastic rods 200.
[0046] Preferably, the conical circumferential surface of the melt compensation zone 220 is an inclined surface or an inwardly concave curved surface, which gives the melt a more reasonable flow channel transition shape during the flow to the core of the bar 200. The inclined surface or the inwardly concave curved surface can effectively guide the melt to flow towards the center along a smooth path, reduce flow resistance and shear stress concentration, and avoid eddies, stagnant material or pressure fluctuations caused by uneven flow. This is conducive to the melt achieving stable and continuous core feeding under the synergistic effect of extrusion pressure and traction resistance, improving filling density, and further suppressing the generation of internal defects.
[0047] Among them, the concave curved surface can enhance the convergence effect of the melt at the front end of the compensation zone and optimize the pressure transmission efficiency, thereby improving the stability and controllability of the molding process. It is particularly suitable for the uniform and dense continuous production of large cross-section bars 200.
[0048] Preferably, the shaping sleeve 130 is composed of an inner sleeve 132 and an outer sleeve 133. The mating surface of the inner sleeve 132 and the outer sleeve 133 is provided with a cooling channel 134 for the flow of cooling medium to form a cooling system. The cooling system continuously cools the peripheral wall of the shaping sleeve 130. Through the heat exchange between the shaping sleeve 130 and the outer wall of the rod 200, a stable gradient solidification front is formed from the outer wall to the core of the rod 200, providing reliable physical conditions for melt compensation.
[0049] Preferably, the cross-sectional area of the feed channel 131 gradually increases from its inlet end to its outlet end. This gradually expanding flow channel design is conducive to the smooth diversion and deceleration of the molten plastic when passing through the die 120, reducing shear heating and flow stress, thereby improving the initial molding quality of the bar 200. At the same time, the cross-sectional area of the outlet end of the feed channel 121 is precisely matched with the cross-sectional area of the inlet end of the melt channel 131, ensuring that there are no obvious steps or gaps when the melt enters the shaping sleeve 130, achieving a smooth transition and preventing material stagnation or eddy currents.
[0050] This structure not only helps maintain a stable melt flow state, but also creates favorable conditions for the subsequent formation of a uniform cooling layer and a stable melt compensation zone 220 within the shaping sleeve 130, improving the dimensional accuracy and surface quality of the bar 200 and enhancing the molding stability and controllability of the entire extrusion system.
[0051] Preferably, the extrusion end of the extruder 100 is connected to the die 120 through the die head body 110. The cross-sectional area of the flow channel at the inlet end of the die head body 110 is larger than the cross-sectional area of the flow channel at its outlet end. This contraction flow channel structure can generate a compression effect when the melt passes through, enhance the shearing action and melt density, thereby effectively increasing the extrusion pressure and making the melt entering the shaping sleeve 130 more compact, providing a basis for subsequent continuous melt compensation.
[0052] The cross-sectional area of the flow channel at the outlet end of the die head 110 is the same as the cross-sectional area of the flow channel at the inlet end of the feed channel 121, so as to achieve seamless connection of the flow channels between the die head 110 and the die 120. This avoids steps, gaps or abrupt changes in cross-section at the connection, effectively preventing eddies, material stagnation or pressure loss in the flow of the melt, and ensuring that the melt can smoothly and continuously enter the die 120 from the die head 110, thus ensuring the uniformity and stability of the flow field.
[0053] Preferably, a heat insulation pad 160 is provided on the mating surface of the die 120 and the shaping sleeve 130 to reduce the heat transfer from the die 120 to the shaping sleeve 130. It should be noted that since the shaping sleeve 130 is equipped with a cooling system, it needs to maintain a low and stable temperature to achieve rapid shaping of the outer wall of the bar 200 and gradient cooling from the outside to the inside. If the die 120 and the shaping sleeve 130 are in direct contact, the high-temperature die 120 will continuously conduct heat to the shaping sleeve 130, causing its local temperature to rise, cooling efficiency to decrease, and affecting the dimensional accuracy and surface quality of the bar 200.
[0054] By setting the heat insulation pad 160, this unexpected heat conduction path is effectively blocked. This not only protects the cooling capacity of the shaping sleeve 130, enabling it to continuously and evenly cool the bar 200 efficiently, but also helps maintain the thermal stability of the exit area of the die 120, preventing the melt from generating stress or flow defects due to excessive temperature difference in the early stage of molding.
[0055] This design achieves physical isolation between the hot and cold zones, ensuring that the cooling process proceeds according to a preset gradient. It provides reliable conditions for the melt to form a stable compensation zone in the core, significantly improving the overall density and molding stability of the large-diameter plastic rod 200.
[0056] Preferably, a rounding device (not shown in the figure) can be added to the outlet end of the shaping sleeve 130. When the bar 200 still has a certain thermoplasticity but has a certain strength, it is subjected to axial rotation extrusion or uniform radial pressure to correct the deformation in real time and improve the roundness of the bar 200.
[0057] Preferably, a spray box 140 is provided between the shaping sleeve 130 and the traction machine 150. The spray box 140 is used to further cool and shape the initially cured rod 200 evenly. Cooling water is continuously sprayed onto the surface of the rod 200 through circumferentially arranged water spray holes or spray pipes, so that its temperature is further reduced and tends to be uniform, completing the complete curing process from the surface to the core. After the rod 200 is cut by the cutting machine, it can be stored.
[0058] The technical means disclosed in this utility model are not limited to those described above, but also include technical solutions composed of any combination of the above technical features. The above are specific embodiments of this utility model. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications are also considered within the scope of protection of this utility model.
[0059] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.
[0060] Furthermore, in this utility model, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. The terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly specified. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0061] The technical solutions of the various embodiments of this utility model can be combined with each other, but only if they can be implemented by those skilled in the art. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the protection scope claimed by this utility model.
[0062] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.
Claims
1. A continuous melt-compensated plastic rod extrusion device, characterized in that, include: An extruder, a die, a shaping sleeve, and a traction machine are arranged coaxially along the material extrusion direction. The inner cavity of the die forms a feeding channel, and the inner cavity of the shaping sleeve forms a melt channel. The feeding channel is connected to the melt channel. The sizing sleeve is provided with a cooling system on its peripheral wall. The cooling system gradually cools the bar located in the melt channel from the outer wall to the core. As the traction machine continues to pull the bar forward, the bar located at the outlet end of the melt channel cools and solidifies to form a solid part, while the bar located at the inlet end of the melt channel is in a molten state and forms a cone-shaped melt compensation zone. The traction speed of the traction machine is less than the extrusion speed of the extruder. The melt located in the melt compensation zone continuously compensates and fills the pre-solidified core of the rod under the combined force of extrusion pressure and traction resistance.
2. The continuous melt-compensated plastic rod extrusion equipment according to claim 1, characterized in that, The diameter of the melt compensation zone gradually decreases along the extrusion direction of the bar and closes at the core of the bar.
3. The continuous melt-compensated plastic rod extrusion equipment according to claim 1, characterized in that, The conical circumferential surface of the melt compensation zone is an inclined surface or an inwardly concave curved surface.
4. A continuous melt-compensated plastic rod extrusion device according to claim 1, characterized in that, The shaping sleeve is composed of an inner sleeve and an outer sleeve. The mating surface of the inner sleeve and the outer sleeve is provided with a cooling channel for the flow of cooling medium to form the cooling system.
5. A continuous melt-compensated plastic rod extrusion device according to claim 1, characterized in that, The cross-sectional area of the feed channel gradually increases from its inlet end to its outlet end to form a gradually expanding flow channel.
6. A continuous melt-compensated plastic rod extrusion device according to claim 1, characterized in that, The cross-sectional area of the outlet flow channel of the feed channel is the same as the cross-sectional area of the inlet flow channel of the melt channel.
7. A continuous melt-compensated plastic rod extrusion device according to claim 1, characterized in that, The extrusion end of the extruder is connected to the die via the die head body, and the cross-sectional area of the flow channel at the inlet end of the die head body is larger than the cross-sectional area of the flow channel at its outlet end.
8. A continuous melt-compensated plastic rod extrusion device according to claim 7, characterized in that, The cross-sectional area of the flow channel at the outlet end of the machine head body is the same as the cross-sectional area of the flow channel at the inlet end of the feed channel.
9. A continuous melt-compensated plastic rod extrusion device according to claim 1, characterized in that, A heat-insulating pad is provided on the mating surface between the die and the shaping sleeve.
10. A continuous melt-compensated plastic rod extrusion device according to claim 1, characterized in that, A spray box is also provided between the shaping sleeve and the traction machine.