Cold extrusion forming apparatus and process

Abstract

The application provides a cold extrusion forming device and process, comprising a female die, a male die and an extrusion driving part, the female die is matched with the male die, the extrusion driving part is in transmission connection with the male die and can drive the male die to move to the female die along a die closing direction to enter a die closing state, a die closing cavity for accommodating a wet embryo is formed between the male die and the female die in the die closing state; the die closing cavity comprises a bottom wall area and a side wall area which are in communication with each other, the side wall area is designed as a die closing gap gradual change structure to reduce the resistance of wet embryo slurry at the connection between the bottom wall area and the side wall area to extend and flow to the side wall area; the die closing pressure of the extrusion driving part driving the male die to move to the die closing state towards the female die is 3t-5t. In this way, the application designs the side wall area of the die closing cavity as a die closing gap gradual change structure, and uses a high die closing pressure of 3t-5t to cold extrude the wet embryo, so that the dehydration rate of the wet embryo in the cold extrusion process is improved, and the strength and yield of the workpiece are also improved.

Description

Technical Field

[0001] This application relates to the field of cold extrusion molding equipment technology, and in particular to a cold extrusion molding equipment and process. Background Technology

[0002] In the traditional wet pressing process of paper-plastic products, the wet blanks after adsorption molding of the mold usually contain extremely high moisture content, often exceeding 70%. Existing technology usually directly sends such high moisture content wet blanks into the drying process. This method is not only inefficient and energy-intensive, but also prone to shrinkage and deformation during the drying process due to the insufficient physical strength of the wet blanks themselves. This results in wrinkles and poor flatness on the surface of the finished product, seriously affecting the appearance quality and structural strength of the workpiece.

[0003] In related technologies, mechanical extrusion dehydration is performed before drying the wet blank. However, when the extrusion pressure is too high, the resistance of the slurry flowing from the bottom wall to the side wall will change abruptly, generating huge shear stress at the corner. This can easily cause the wet blank to tear or break at the joint. Therefore, in practical applications, the mold closing pressure is usually limited, and the maximum pressure is usually controlled within 1.3t to avoid excessive pressure causing the workpiece to break. However, due to the limitation of this low pressure, although the yield rate can be maintained, the dehydration rate of the workpiece is insufficient, resulting in poor drying efficiency and finished product strength. Summary of the Invention

[0004] This application provides a cold extrusion molding equipment and process to at least solve the above-mentioned problems in the related art.

[0005] To achieve the above objectives, this application provides the following technical solution: a cold extrusion molding equipment, including a female mold, a male mold and an extrusion drive component, wherein the female mold and the male mold are adapted to each other and spaced apart along the mold closing direction, the extrusion drive component is connected to the male mold in a transmission manner and is able to drive the male mold to move along the mold closing direction until the male mold and the female mold enter the mold closing state, wherein in the mold closing state, a mold closing cavity for accommodating the wet blank is formed between the male mold and the female mold; The mold cavity includes an interconnected bottom wall region and a side wall region. The side wall region is configured with a gradually changing mold gap structure. The gradually changing mold gap structure is constructed such that the mold gap in the side wall region of the mold cavity gradually decreases from the end away from the bottom wall region to the end closer to the bottom wall region. This causes the gap for the wet slurry to extend and flow towards the side wall region at the connection between the bottom wall region and the side wall region to gradually increase, thereby reducing the resistance to the wet slurry extending and flowing towards the side wall region at the connection between the bottom wall region and the side wall region. The closing pressure when the extrusion drive moves the male mold toward the female mold to the mold closing state is 3t-5t.

[0006] In some alternative implementations, a chamfered structure is provided at the connection between the bottom wall region and the side wall region of the mold cavity.

[0007] In some alternative embodiments, the cold extrusion molding equipment further includes a water guiding assembly, which includes a water guiding plate and a switch valve. The water guiding plate has a water guiding groove on the side facing the mold and is fixedly connected to the bottom wall of the mold. The water guiding groove is connected to the switch valve through a conduit. The bottom wall of the water guide channel is provided with multiple drainage holes, which are connected to the water storage tank through conduits. The bottom wall of the water guide channel forms a water guiding slope. The male mold has multiple through holes, and the mold cavity is connected to the water guide groove through each through hole.

[0008] In some alternative embodiments, the extrusion drive includes a servo hydraulic cylinder that is connected to the die drive to drive the die to move in the die closing direction.

[0009] In some optional embodiments, either the female mold or the male mold has at least one guide groove in its circumferential region, and the other has at least one guide body in its circumferential region. When the extrusion drive drives the male mold to move toward the female mold to the mold-closing state, the guide body is inserted into the guide groove along the mold-closing direction and slides into the guide groove.

[0010] In some optional embodiments, the female mold is provided with multiple through holes, which are connected to the mold cavity and to the negative pressure component through a conduit. When the male mold and the female mold are separated, the negative pressure component can generate negative pressure, so that the female mold can adsorb and grasp the wet blank after squeezing and dehydration through negative pressure.

[0011] In some optional embodiments, when the female mold and male mold are in the closed state, the mold closing gap in the bottom wall region of the mold cavity is A, and the mold closing gap in the side wall region gradually transitions from A to B; wherein, 1.5mm≤A≤1.7mm, B=A+0.5mm.

[0012] In some optional embodiments, this application also provides a cold extrusion molding process applied to the above-mentioned cold extrusion molding equipment, the process comprising: A wet embryo is prepared by suction molding of a suspension using a common mold. During cold extrusion, the extrusion drive outputs a die-closing pressure of 3t-5t to drive the male die to move toward the female die and extrude the wet blank; The gradually changing gap structure in the sidewall area guides the wet slurry from the bottom wall area to extend and flow towards the sidewall area, while the moisture in the wet slurry is discharged outward through the through holes on the male mold.

[0013] In some alternative embodiments, during cold extrusion, the extrusion drive drives the male mold to move toward the female mold at a preset speed until it enters the mold closing state, and holds the wet blank under pressure for a preset time. After the wet blank is held under pressure for a preset time, the male mold is driven to move away from the female mold by the extrusion drive component, and gas is introduced into the mold cavity to achieve pressure relief and mold separation.

[0014] In some alternative implementations, the surface of the wet blank is dehydrated by a negative pressure pump after the wet blank is formed by suction molding of the mold and after depressurization and mold separation.

[0015] In the aforementioned cold extrusion molding equipment, by employing a high die-closing pressure of 3t-5t, the fiber density and dehydration rate of the wet preform are significantly improved, solving the problems of high moisture content and insufficient strength of the workpiece caused by traditional low-pressure molding (usually 1.2t-1.3t). By gradually reducing the die-closing gap in the sidewall region from the end away from the bottom wall region to the end closer to the bottom wall region, the resistance at the connection between the sidewall region and the bottom wall region can be smoothly transitioned under high extrusion pressure, avoiding the huge shear stress generated by the slurry due to flow obstruction under high pressure, reducing the risk of the wet preform being torn at the connection, and solving the problem of low workpiece yield under high die-closing pressure. Thus, by designing the sidewall region of the die-closing cavity as a gradually changing die-closing gap structure and using a high die-closing pressure of 3t-5t for cold extrusion of the wet preform, this application achieves not only improved dehydration rate of the wet preform during cold extrusion but also improved workpiece strength and yield.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0017] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0018] Figure 1 This paper shows a schematic diagram of the structure of the female mold, male mold, and extrusion drive component in the cold extrusion molding equipment of this application; Figure 2 It shows Figure 1 A schematic diagram of the female mold, male mold, and water guiding components when the female mold and male mold are in the mold closing state; Figure 3 It shows Figure 2 A cross-sectional view of the female mold, male mold, and water guiding components along the III-III direction when the female mold and male mold are in the mold-closed state. Figure 4 It shows Figure 2 Exploded view of the female mold, male mold, and water guiding components; Figure 5 This illustration shows a schematic diagram of the bottom wall region and side wall region of the mold cavity when the female mold and male mold are in the mold-closed state in an embodiment of this application. Figure 6 A schematic diagram of the cold extrusion molding equipment in an embodiment of this application is shown; Figure 7 It shows Figure 6 Schematic diagram of the structure of the extrusion drive component; Figure 8 A schematic diagram of the workpiece structure in an embodiment of this application is shown; Figure 9 A schematic diagram of the moisture content data table for different slurries extruded during cold extrusion is shown in the embodiments of this application; Figure 10 A comparison diagram of tensile strength between cold extrusion and non-cold extrusion processes is shown in the embodiments of this application.

[0019] The following are the labeling instructions in the diagram: 11. Female mold; 111. Through hole; 12. Male mold; 121. Through hole; 13. Extrusion drive component; 131. Servo hydraulic cylinder; 132. Movable plate; 133. Guide rod; 134. Bearing plate; 135. Connecting plate; 14. Mold cavity; 141. Bottom wall area; 142. Side wall area; 15. Water guiding assembly; 151. Water guiding plate; 152. Water guiding groove; 153. Drain hole; 154. Switch valve; 16. Guide body; 17. Guide groove; 18. Frame; 20. Workpiece. Detailed Implementation

[0020] To make the objectives, features, and advantages of this application more apparent and understandable, 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 of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] In related technologies, mechanical extrusion dehydration is performed before drying the wet blank. However, when the extrusion pressure is too high, the resistance of the slurry flowing from the bottom wall to the side wall will change abruptly, generating huge shear stress at the corner. This can easily cause the wet blank to tear or break at the joint. Therefore, in practical applications, the mold closing pressure is usually limited, and the maximum pressure is usually controlled within 1.3t (i.e., 1.3 tons) to avoid excessive pressure causing the workpiece to break. However, due to the limitation of this low pressure, although the yield rate is maintained, the dehydration rate of the workpiece is insufficient, resulting in poor drying efficiency and finished product strength.

[0024] To address the problems existing in the aforementioned related technologies, this application significantly improves the fiber density and dehydration rate of the wet blank by adopting a high die-clamping pressure of 3t-5t (i.e., 3-5 tons), solving the problem of high moisture content and insufficient strength of the workpiece caused by traditional low-pressure molding (usually 1.2t-1.3t). By gradually reducing the die-clamping gap in the side wall region from the end away from the bottom wall region to the end closer to the bottom wall region, the resistance at the connection between the side wall region and the bottom wall region can be smoothly transitioned under high extrusion pressure, avoiding the huge shear stress generated by the slurry due to flow obstruction under high pressure, reducing the risk of the wet blank being torn at the connection, and solving the problem of low workpiece yield under high die-clamping pressure. Thus, by designing the side wall region of the die-clamping cavity as a gradually changing die-clamping gap structure and using a high die-clamping pressure of 3t-5t for cold extrusion of the wet blank, this application achieves not only improved dehydration rate of the wet blank during cold extrusion, but also improved workpiece strength and yield.

[0025] The embodiments of this application are described below with reference to the accompanying drawings.

[0026] It should be noted that the mold closing direction in this application is the vertical direction, that is, the up and down direction when the equipment is in use.

[0027] Combination Figure 1 , Figure 2 and Figure 3 , Figure 1 This is a structural schematic diagram of the female mold 11, the male mold 12, and the extrusion drive component 13. Figure 2 This is a structural schematic diagram of the female mold 11, the male mold 12, and the water guiding component 15. Figure 3This is a cross-sectional view of the female mold 11, male mold 12, and water guiding component 15 along the III-III direction. In some embodiments, this application provides a cold extrusion molding device, including a female mold 11, a male mold 12, and an extrusion drive component 13. The female mold 11 and male mold 12 are adapted to each other and spaced apart along the mold closing direction. The male mold 11 can be driven to move along the mold closing direction until the male mold 12 and female mold 11 enter the mold closing state. In the mold closing state, a mold closing cavity 14 for accommodating the wet blank is formed between the male mold 12 and the female mold 11. Specifically, the male mold 12 has a male mold cavity on the side facing the female mold 11, and the female mold 11 has a female mold cavity on the side facing the male mold 12. The outlines of the male mold cavity and the female mold cavity correspond to the lower and upper shapes of the finished workpiece 20, respectively. After the male mold 12 and female mold 11 are closed, the male mold cavity and the female mold cavity surround each other to form the mold closing cavity 14. The wet blank that has not undergone extrusion is placed in the cavity of the male mold 12. During the extrusion process, the wet blank... The material undergoes stretching and deformation, ultimately conforming to the contour of the mold cavity 14 and completing its shape. The mold cavity 14 includes a bottom wall region 141 and a side wall region 142 that are interconnected. The mold clearance of the bottom wall region 141 remains constant, while the side wall region 142 is configured with a gradually changing mold clearance structure. This structure is designed so that the mold clearance of the mold cavity 14 in the side wall region 142 gradually decreases from the end away from the bottom wall region 141 towards the end closer to the bottom wall region 141. This causes the gap for the wet slurry to extend and flow towards the side wall region 142 at the connection between the bottom wall region 141 and the side wall region 142 to gradually increase, thereby reducing the resistance to the extension and flow of the wet slurry towards the side wall region 142 at the connection between the bottom wall region 141 and the side wall region 142. The extrusion drive 13 drives the male mold 12 to move along the mold closing direction until the mold closing pressure when the male mold 12 and the female mold 11 enter the mold closing state is 3t-5t. For example, the wet blank can be a laptop packaging box.

[0028] In the aforementioned cold extrusion molding equipment, by employing a high die-closing pressure of 3t-5t, the fiber density and dehydration rate of the wet blank are significantly improved, solving the problem of high moisture content and insufficient strength of the workpiece 20 caused by traditional low-pressure (e.g., 1.2t-1.3t) molding. By gradually reducing the die-closing gap of the side wall region 142 from the end away from the bottom wall region 141 toward the end closer to the bottom wall region 141, the resistance at the connection between the side wall region 142 and the bottom wall region 141 can be smoothly transitioned under high extrusion pressure, avoiding the huge shear stress generated by the slurry due to flow obstruction under high pressure, reducing the risk of the wet blank being torn at the connection, and solving the problem of low yield of workpiece 20 under high die-closing pressure. Thus, by designing the side wall region 142 of the die-closing cavity 14 as a gradually changing die-closing gap structure and using a high die-closing pressure of 3t-5t for cold extrusion of the wet blank, this application achieves not only improved dehydration rate of the wet blank during cold extrusion but also improved strength and yield of workpiece 20.

[0029] In some embodiments, a chamfered structure is provided at the connection between the bottom wall region 141 and the side wall region 142 of the mold cavity 14.

[0030] Thus, the connection between the bottom wall region 141 and the side wall region 142 is smoothly transitioned through a chamfered structure, further eliminating abrupt changes in the cavity inflection point. This makes the slurry flow more gently at the connection point. Combined with the gradual change structure of the mold closing gap, it further mitigates the extrusion shear stress, avoids local tensile breakage of the fibers, and facilitates the continuous interweaving and molding of the slurry fibers at the corner. This enhances the structural strength of the wet preform at the connection between the bottom wall region 141 and the side wall region 142, further reduces the probability of corner tearing of the wet preform during high-pressure extrusion, and improves the yield of the workpiece 20.

[0031] It is understandable that the essence of the fracture of the paper-plastic workpiece 20 is that the fibers are torn at the junction, and the fiber layers separate. The mold side wall and bottom wall cavity adopt a smooth arc transition, combined with the gradual side gap design. During extrusion, the horizontal fibers in the bottom wall area 141 and the vertical fibers in the side wall area 142 are gently bent and continuously interwoven in the gradual gap space, and will not be forcibly bent or stretched at right angle positions, which will lead to fracture. The fixed plane gap ensures that the bottom wall fibers are dense, and the gradual side gap ensures that the fiber density of the side wall gradually decreases from the junction to the outside. The fiber density is the highest and the interweaving is the tightest at the junction, forming a mechanical reinforcement zone and avoiding stress concentration fracture.

[0032] In some preferred embodiments, the chamfer structure may employ a straight chamfer transition or a rounded chamfer transition.

[0033] Combination Figure 4 , Figure 4 This is an exploded structural diagram of the female mold 11, male mold 12, and water guiding assembly 15. In some embodiments, the cold extrusion molding equipment further includes a water guiding assembly 15, which includes a water guiding plate 151 and a switching valve 154. The water guiding plate 151 has a water guiding groove 152 on the side facing the male mold 12 and is fixedly connected to the bottom wall of the male mold 12. The water guiding groove 152 is connected to the switching valve 154 through a conduit. The bottom wall of the water guiding groove 152 has multiple drainage holes 153, which are connected to a water storage tank through conduits. The bottom wall of the water guiding groove 152 forms a water guiding slope. The male mold 12 has multiple through holes 121, and the mold cavity 14 communicates with the water guiding groove 152 through each through hole 121. Exemplarily, the switching valve 154 can be an angle seat valve.

[0034] Thus, on the one hand, during high-pressure extrusion, a large amount of internal free water is released from the wet blank. The slope of the guide slope itself generates a gravity-guided effect, allowing the free water to flow along the guide slope. The component of gravity along the guide slope propels the water flow, enabling it to be discharged more quickly through the drain hole 153. The flowing water also reduces the water seal effect caused by eddies, reducing the retention and accumulation of extruded free water in the guide groove 152. On the other hand, during cold extrusion, the switch valve 154 is opened, and external air enters the guide groove 152 and the drain pipe through the switch valve 154. The airflow flows along the guide groove 152 to the drain hole 153 and along the drain channel, breaking the water seal effect in the drain hole 153 and the drain pipe, eliminating negative pressure resistance, and preventing the extruded free water from flowing back into the guide groove 152 and the interior of the wet blank. At the same time, the airflow can also agitate the accumulated water, allowing it to flow out quickly with the combination of the flow on the guide slope and the agitation of the airflow, further reducing the risk of water accumulation.

[0035] It is understandable that most of the fractures of workpiece 20 are caused by water accumulation at the junction of side wall region 142 and bottom wall region 141, excessive moisture content, insufficient fiber strength, or excessively rapid local dehydration leading to dryness, hardness, and brittleness. During cold extrusion, the water accumulated in the water guide groove 152 flows back to the mold cavity 14 along the through hole 121 and tends to accumulate at the junction of side wall region 142 and bottom wall region 141, resulting in excessive moisture content, insufficient strength, and easy fracture at this junction. Therefore, it is necessary to avoid water accumulation in the water guide groove 152.

[0036] In some preferred embodiments, the switching valve 154 is connected to an air pump to allow positive pressure airflow to be introduced into the water guide trough 152, thereby improving drainage efficiency and further reducing the risk of water accumulation in the water guide trough 152.

[0037] Combination Figure 4 In some preferred embodiments, the drain hole 153 is a conical hole. The conical structure of the conical hole can reduce water flow resistance, improve drainage efficiency, and further reduce the risk of water accumulation in the water guide channel 152.

[0038] In some preferred embodiments, there are two or more drainage holes 153, which are distributed at intervals along the inclined path of the water guide slope. In this way, the drainage holes 153 are arranged at multiple points along the water flow path of the water guide slope, so that the squeezed and separated water can be diverted and discharged from multiple drainage holes 153 nearby during the flow on the slope, avoiding local water accumulation and blockage in the water guide channel 152 and accelerating the overall drainage rate.

[0039] In some alternative embodiments, the bottom wall of the water guide trough 152 is gradually raised from one side to the other in the horizontal direction, so that the distance between it and the bottom surface of the mold 12 gradually decreases in one direction, and the squeezed water flows unidirectionally along the slope to the drain hole 153.

[0040] In some alternative embodiments, the water guiding slope is arranged such that the bottom wall of the water guiding channel 152 is designed to gradually rise from the surrounding edges to the center area, so that the distance between the bottom wall and the bottom surface of the mold 12 gradually increases from the center area to the edge, and the squeezed water is diverted and discharged from the center of the channel to the periphery.

[0041] It should be noted that the above-mentioned arrangement of the inclined surfaces is merely an example. This application does not limit the specific arrangement of the inclined surfaces. Any structural scheme that can form a slope at the bottom of the water guide channel 152 to guide the flow and realize the directional collection and discharge of accumulated water should be included in the protection scope of this application.

[0042] In some embodiments, the extrusion drive 13 includes a servo hydraulic cylinder 131, which is connected to the male mold 12 for driving the male mold 12 to move along the mold closing direction. Thus, by using the servo hydraulic cylinder 131 as the extrusion drive 13, the mold closing speed, holding time, and 3t-5t extrusion pressure can be precisely controlled, achieving segmented actions of slow mold closing, high-pressure holding, and smooth mold opening; avoiding damage to the wet blank caused by instantaneous high-pressure impact; adapting to the molding requirements of different slurry raw materials; ensuring stable pressure output; guaranteeing the stable performance of the flow guiding effect of the gradient gap structure; and improving the uniformity of blank molding and the yield of the workpiece.

[0043] It should be noted that cylinders are difficult to provide driving force of more than 3t, and when faced with high-difficulty cold extrusion processes, the airflow speed and flow rate fluctuate greatly, the mold closing speed and pressure stability are poor, making it difficult to accurately match the process rhythm of cold extrusion. The pneumatic system response is lagging, and it is impossible to achieve complex pressure curve control, which limits the forming accuracy of the workpiece.

[0044] In some specific embodiments, the male mold 12, female mold 11, and servo hydraulic cylinder 131 are configured in two sets. Each set of male mold 12, female mold 11, and servo hydraulic cylinder 131 constitutes an independent cold extrusion station, and the two sets of servo hydraulic cylinders 131 share the same hydraulic oil tank. In this way, the equipment footprint can be reduced, the cost of oil tank accessories can be lowered, and independent control of pressure and operating speed of the two stations can be achieved, avoiding the problem of interference in the linkage of station actions caused by a single oil supply. The process parameters on one side can be set separately according to the specifications of the workpiece 20, effectively improving the adaptability and flexibility of equipment production.

[0045] Combination Figure 4 In some embodiments, either the female mold 11 or the male mold 12 has at least one guide groove 17 in its circumferential region, that is, the number of guide grooves 17 is one or more, and the other has at least one guide body 16 in its circumferential region, that is, the number of guide bodies 16 is one or more. When the extrusion drive 13 drives the male mold 12 to move toward the female mold 11 to the mold closing state, the guide body 16 is inserted into the guide groove 17 along the mold closing direction and slides in cooperation with the guide groove 17.

[0046] Thus, the guide body 16 and the guide groove slide and limit each other, so that the mold can be accurately aligned during the mold closing and mold opening process, avoiding the female mold 11 and male mold 12 from being misaligned under high pressure extrusion conditions, ensuring that the gaps in all parts of the mold cavity 14 are stable and consistent, thereby making the wet slurry uniformly pressurized, preventing local overpressure tearing or uneven extrusion and dehydration, and further improving the forming consistency of the workpiece 20.

[0047] Combination Figure 3 In some embodiments, the female mold 11 is provided with a plurality of through holes 111, one end of which is connected to the mold cavity 14, and the other end is connected to a negative pressure assembly through a conduit. The negative pressure assembly is used to generate negative pressure. For example, the negative pressure assembly can be an air pump.

[0048] Thus, the through hole 111 connects the mold cavity 14 with the negative pressure component. On the one hand, the negative pressure component can extract the free water on the surface of the wet blank after the male mold 12 sucks the slurry and forms it. On the other hand, when the mold is separated, air can be introduced into the cavity through the through hole 111 to break the negative pressure adsorption force, so as to demold smoothly and prevent the wet blank from being pulled and damaged. Furthermore, after the mold is separated, the negative pressure component can make the through hole 111 form a negative pressure cavity, so that the female mold 11 can adsorb and remove the wet blank after cold extrusion and dehydration, which facilitates the operation of the workpiece 20 and connects to the next dehydration process, simplifying the operation process.

[0049] Combination Figure 5 , Figure 5 This is a schematic diagram of the bottom wall region 141 and the side wall region 142 of the mold cavity 14. In some embodiments, when the female mold 11 and the male mold 12 are in the mold-closed state, the mold-closed gap of the bottom wall region 141 of the mold cavity 14 is A, and the mold-closed gap of the side wall region 142 gradually transitions from A to B. Wherein, 1.5mm≤A≤1.7mm, B=A+0.5mm.

[0050] Thus, if the mold closing gap of the bottom wall region 141 is less than 1.5mm, the slurry flow resistance at the right-angle connection between the side wall region 142 and the bottom wall region 141 will surge instantly. Under high pressure, the slurry flowing from the bottom wall to the side wall will be blocked, generating huge shear stress, directly tearing the junction of the side wall region 142 and the bottom wall region 141. If the mold closing gap of the bottom wall region 141 is greater than 1.7mm, it will result in the workpiece 20 being too thick after drying. On the other hand, the mold closing gap of the side wall region 142 gradually increases from the inside to the outside, with a gap of 1.5mm near the connection, which is consistent with the mold closing gap of the bottom wall region 141. The slurry flow rate and pressure transition smoothly, gradually widening to 2.0mm outward. The slurry flow resistance of the side wall region 142 gradually decreases, with no sudden resistance changes and no stress peaks, completely avoiding shearing and tearing at the junction.

[0051] In some preferred embodiments, the male mold 12 may be made of AL6061 aluminum alloy, which has resistance to deformation and fatigue. Under long-term high-pressure cold extrusion, the mold gap gradually changes structure, and the size of the chamfer transition area does not undergo thermal deformation or elastic deformation. This avoids the formation of sharp steps between the side wall and bottom wall after mold wear, which would increase the risk of tearing of the wet blank.

[0052] In some specific embodiments, the male mold 12 and the female mold 11 are arranged opposite each other in the vertical direction and are located on the lower side of the female mold 11. The extrusion drive 13 is located on the side of the female mold 11 away from the male mold 12 and is connected to the male mold 12 in a transmission manner. The extrusion drive 13 is used to drive the male mold 12 to move upward in the vertical direction.

[0053] Combination Figure 6 and Figure 7 , Figure 6 This is a schematic diagram of the structure of a cold extrusion molding equipment. Figure 7 This is a schematic diagram of the structure of the extrusion drive 13; in some specific embodiments, the equipment also includes a frame 18, and the extrusion drive 13 and the die 11 are both fixedly connected to the frame 18. The extrusion drive component 13 also includes a movable plate 132, multiple guide rods 133, a bearing plate 134, and a connecting plate 135. The female mold 11 is fixedly connected to the frame 18 through the connecting plate 135. The connecting plate 135 can reduce the risk of local upward arching deformation of the female mold 11 during high-pressure cold extrusion. The bearing plate 134 is used to support and position the male mold 12. Multiple guide rods 133 are arranged circumferentially with the center line of the bearing plate 134 as the axis. One end of each guide rod 133 is fixedly connected to the bearing plate 134, and the other end is fixedly connected to the movable plate 132. The middle part of each guide rod 133 is slidably connected to the frame 18 to improve the motion accuracy of the male mold 12 supported by the bearing plate 134 when it moves upward. The movable plate 132 is fixedly connected to the servo hydraulic cylinder 131. The servo hydraulic cylinder 131 drives the male mold 12 to move upward to the mold closing state through the movable plate 132 and multiple guide rods 133.

[0054] In some embodiments, this application also provides a cold extrusion molding process applied to the aforementioned cold extrusion molding equipment, the process including: A wet embryo is prepared by suction molding of the suspension using mold 12. During cold extrusion, the extrusion drive 13 outputs a closing pressure of 3t-5t to drive the male mold 12 toward the female mold 11 and extrude the wet blank; The gradually changing gap structure of the side wall region 142 guides the wet slurry of the bottom wall region 141 to extend and flow towards the side wall region 142, and the moisture of the wet slurry is discharged outward through the through hole 121 on the male mold 12.

[0055] In this way, a wet preform is first obtained by suction molding, and then extrusion is carried out using a 3t-5t press with a gradually changing gap structure. The slurry can be smoothly extended along the cavity, avoiding local shearing damage. The water extruded is quickly discharged through the through hole 121 of the male mold, which effectively reduces the water consumption in subsequent drying and reduces drying energy consumption. At the same time, the fibers are compacted and dense, improving the strength of the finished product and the yield of the workpiece.

[0056] In some embodiments, during cold extrusion, the extrusion drive 13 drives the male mold 12 to move toward the female mold 11 at a preset speed to enter the mold closing state, and holds the wet blank under pressure for a preset time; after the wet blank is held under pressure for a preset time, the extrusion drive 13 drives the male mold 12 to move away from the female mold 11, and introduces gas into the mold closing cavity 14 to achieve pressure relief and mold separation.

[0057] In this way, the mold closes slowly at a preset speed, the slurry is spread evenly, and the instantaneous impact avoids damage to the blank. The pressure holding time is preset to ensure that the pressure of 3t to 5t is fully applied to the wet blank, so as to fully squeeze out the moisture inside the wet blank and promote the dense formation of fibers. When the mold is opened, air is vented into the mold cavity 14 to break the negative pressure adsorption, eliminate the adsorption force between the mold and the wet blank, achieve smooth and damage-free mold separation, and prevent the blank from being deformed and damaged due to demolding.

[0058] In some preferred embodiments, the preset speed can be 5-15 mm / s; the preset pressure holding time can be 3-8 seconds.

[0059] In some embodiments, after the wet blank is formed by suction molding of the male mold 12 and after depressurization and mold separation, the surface of the wet blank is dehydrated by a negative pressure pump.

[0060] Thus, negative pressure pre-dehydration after slurry forming removes free water from the surface of the wet blank in advance, reduces the drainage volume of subsequent high-pressure extrusion, and prevents a large amount of water from accumulating in the mold cavity and forming a water seal that hinders drainage; negative pressure dehydration again after mold separation further removes residual surface moisture from the blank and reduces the drying energy consumption of the subsequent drying process.

[0061] Example Control group: Utilizing traditional paper-plastic molding technology, without a pre-extrusion cold extrusion process, relying solely on subsequent high-temperature drying and dehydration; the mold cavity employs a fixed, equal-gap structure with right-angle corners; combined with... Figure 8 , Figure 8 This is a structural schematic diagram of workpiece 20; the molded workpiece 20 is a laptop box with multiple bends and corners.

[0062] Experimental Group: A wet blank was prepared by suction molding of the suspension using a male mold 12; during cold extrusion, the male mold 12 was driven to move toward the female mold 11 and extrude the wet blank by the extrusion drive 13 outputting a mold closing pressure of 3t-5t; the gradually changing structure of the mold closing gap in the side wall region 142 guided the wet blank slurry in the bottom wall region 141 to extend and flow toward the side wall region 142, and the moisture in the wet blank was discharged outward through the through hole 121 on the male mold 12; during cold extrusion, the extrusion drive 13 drove the male mold 12 to move toward the female mold 11 at a preset speed to enter the mold closing state, and kept the wet blank under pressure for a preset time; after the wet blank was kept under pressure for a preset time, the male mold 12 was driven to move away from the female mold 11 by the extrusion drive 13, and gas was introduced into the mold closing cavity 14 to achieve pressure relief and mold separation; after suction molding of the wet blank by the male mold 12 and after pressure relief and mold separation, the surface of the wet blank was dehydrated by a negative pressure pump.

[0063] Four commonly used pulps were selected for the experiment: premium pulp, premium bamboo pulp, ordinary pulp, and wheat straw pulp. Comparative experiments were conducted on each, and key indicators such as extrusion moisture, wet paper moisture content, and tensile strength of the finished product were statistically analyzed. Specifically, the premium pulp used bamboo pulp and sugarcane as raw materials, while the ordinary pulp used corrugated paper pulp as raw materials.

[0064] Combination Figure 9 , Figure 9 Table of moisture content data for different slurries extruded during cold extrusion; test results of moisture content and dehydration rate: Premium slurry group: The experimental group had an original wet blank of 275g, and a wet blank of 235g after extrusion. The water content of the wet blank after extrusion was 40g. The water content of the wet blank after extrusion was 63%. The control group did not have cold extrusion. The water content of the wet blank was greater than 70%. All the water was removed by drying.

[0065] High-quality bamboo pulp group: The experimental group had an initial wet blank weight of 275g, which increased to 235g after extrusion, with 40g of water squeezed out, resulting in a wet blank moisture content of 63%; the control group had a wet blank moisture content greater than 70%.

[0066] Ordinary slurry group: The experimental group initially produced 310g of wet preform, which was 235g after extrusion, with 75g of water removed. The moisture content of the wet preform after extrusion was as low as 59%, representing the best dewatering effect in this group; the control group had a moisture content greater than 70%. Wheat straw slurry group: The initial wet blank in the experimental group was 280g, and after extrusion it was 235g, with 45g of water squeezed out. The moisture content of the wet blank after extrusion was 63%; the moisture content of the wet blank in the control group was greater than 70%.

[0067] Thus, the experimental group used cold extrusion, while the control group did not use cold extrusion. Compared with the traditional non-cold extrusion process, the cold extrusion of this application can remove a large amount of free water in advance, and the moisture content of the wet blank is reduced from the conventional 70% or more to the range of 59% to 63%, which greatly reduces the amount of water to be evaporated in the subsequent drying process and significantly reduces the heat energy consumption and production time of the drying process.

[0068] Combination Figure 10 , Figure 10 Comparison of tensile strength between cold extrusion and non-cold extrusion processes; results of strength tests on workpiece 20: In the high-quality slurry group, the tensile strength of the control group was 11 MPa, and the tensile strength of the experimental group was 17 MPa.

[0069] In the high-quality bamboo pulp group, the tensile strength of the control group was 0 MPa (workpiece 20 was easily broken, and no valid data was obtained), while the tensile strength of the experimental group was 11 MPa.

[0070] In the ordinary slurry group, the tensile strength of the control group was 6.5 MPa, and the tensile strength of the experimental group was 14.5 MPa.

[0071] In the wheat straw slurry group, the tensile strength of the control group was 6.5 MPa, and the tensile strength of the experimental group was 11 MPa.

[0072] Thus, the tensile strength of the workpiece 20 processed by the cold extrusion molding equipment of this application is significantly improved.

[0073] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A cold extrusion molding equipment, characterized in that, It includes a female mold, a male mold, and an extrusion drive. The female mold is adapted to the male mold and is spaced apart along the mold closing direction. The extrusion drive is connected to the male mold and can drive the male mold to move along the mold closing direction until the male mold and the female mold enter the mold closing state. In the mold closing state, a mold closing cavity for accommodating the wet blank is formed between the male mold and the female mold. The mold cavity includes a bottom wall region and a side wall region that are interconnected. The side wall region is configured with a gradually changing mold gap structure. The gradually changing mold gap structure is constructed such that the mold gap in the side wall region of the mold cavity gradually decreases from one end away from the bottom wall region to one end closer to the bottom wall region. This causes the gap for the wet slurry to extend and flow towards the side wall region at the connection between the bottom wall region and the side wall region to gradually increase, thereby reducing the resistance to the wet slurry extending and flowing towards the side wall region at the connection between the bottom wall region and the side wall region. The extrusion drive unit drives the male mold to move along the mold closing direction until the male mold and the female mold enter the mold closing state. The mold closing pressure is 3t-5t.

2. The cold extrusion molding equipment according to claim 1, characterized in that, A chamfered structure is provided at the connection between the bottom wall region and the side wall region of the mold cavity.

3. The cold extrusion molding equipment according to claim 1, characterized in that, The cold extrusion molding equipment also includes a water guiding assembly, which includes a water guiding plate and a switch valve. The water guiding plate has a water guiding groove on the side facing the mold and is fixedly connected to the bottom wall of the mold. The water guiding groove is connected to the switch valve through a conduit. The bottom wall of the water guide channel is provided with multiple drainage holes, which are connected to the water storage tank through conduits. The bottom wall of the water guide channel forms a water guiding slope. The male mold is provided with multiple through holes, and the mold cavity is connected to the water guide groove through each of the through holes.

4. The cold extrusion molding equipment according to claim 1, characterized in that, The extrusion drive includes a servo hydraulic cylinder, which is connected to the male mold for driving the male mold to move along the mold closing direction.

5. The cold extrusion molding equipment according to claim 1, characterized in that, The female mold and the male mold are provided with at least one guide groove in their circumferential area, and the other mold is provided with at least one guide body in its circumferential area. When the extrusion drive drives the male mold to move toward the female mold to the mold closing state, the guide body is inserted into the guide groove along the mold closing direction and slides in cooperation with the guide groove.

6. The cold extrusion molding equipment according to claim 1, characterized in that, The female mold has multiple through holes, which are connected to the mold cavity and to the negative pressure component through a conduit. When the male mold and the female mold separate, the negative pressure component can generate negative pressure, so that the female mold can adsorb, grab, squeeze and dehydrate the wet blank through negative pressure.

7. The cold extrusion molding equipment according to claim 1, characterized in that, When the female mold and the male mold are in the closed state, the mold closing gap in the bottom wall region of the mold cavity is A, and the mold closing gap in the side wall region gradually transitions from A to B; wherein... 1.5mm≤A≤1.7mm, B=A+0.5mm.

8. A cold extrusion molding process, applied to the cold extrusion molding equipment according to any one of claims 1-7, characterized in that, The process includes: A wet embryo is prepared by suction molding of the suspension using the aforementioned mold. During cold extrusion, the extrusion drive outputs a die-closing pressure of 3t-5t to drive the male die to move toward the female die and extrude the wet blank; The gradually changing gap structure in the sidewall region guides the wet slurry in the bottom wall region to extend and flow towards the sidewall region, and the moisture in the wet slurry is discharged outward through the through holes on the male mold.

9. The cold extrusion molding process according to claim 8, characterized in that, During cold extrusion, the extrusion drive drives the male mold to move toward the female mold at a preset speed until it enters the mold closing state, and holds the wet blank under pressure for a preset time; After the wet blank is held under pressure for a preset time, the male mold is driven by the extrusion drive to move away from the female mold, and gas is introduced into the mold cavity to achieve pressure relief and mold separation.

10. The cold extrusion molding process according to claim 8, characterized in that, After the wet blank is formed by suction molding of the mold and after the mold is depressurized and separated, the surface of the wet blank is dehydrated by a negative pressure pump.

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