One-step molding device and method for producing flat plastic mesh

Abstract

The present invention discloses a one-step molding device and method for producing a flat plastic mesh, which solves the technical problem of reducing the production cost of the plastic mesh and causing material waste. The core technical solution of the present invention is to change the flow direction of the raw material in the molten state at the lip of the slit by the intermittent up and down movement of the knife mold in the molding mold, and utilizes the tooth-shaped structure in the mold, that is, the raised part will block the flow direction of the raw material, while the groove can allow the raw material to flow out to realize the mesh forming process. The process of the present invention is greatly simplified, and the production efficiency is improved. The flat plastic mesh product is a completely continuous product, which can be arbitrarily cut according to demand later, solving the problem of creases that cannot be removed in the production of the disclosed technical method; in addition, the product after one-step molding has no overlap points, and there is no stress concentration phenomenon caused by punching, so the mesh after molding has high tensile strength and enhanced tear resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of plastic net production, and specifically relates to a molding device and method for producing a flat plastic net, in particular to a device and a molding method for realizing plastic net molding in one step. Background Art

[0002] In the field of mesh production technology for plastic extrusion processing, the processing methods currently disclosed are: 1) using two circular molds, an inner mold and an outer mold, both of which have grooves, and forming a diamond-shaped plastic mesh cylinder through the different rotations of the inner mold and the outer mold, and then cooling and shaping it through a shaping cylinder. The mesh cylinder after cooling and shaping is cut open with a blade, and then the mesh cylinder is unfolded to form a mesh. The disclosed patent technologies include US4057449 and CN205167609U. 2) Using two circular inner and outer molds and a circular cutter, the inner mold is provided with a groove, and the gap between the inner and outer molds is used to extrude a viscous cylindrical object, and then the cutter is used to perform a cyclic reciprocating motion to cut out a cylindrical mesh cylinder with rectangular mesh holes, which is shaped by a circular shaping cylinder, cut open by a cutter, and then unfolded to form a mesh sheet. The disclosed patent technologies include US4656075, CN205929395U, and CN206830576U. 3) Using a flat die head to shape and extrude a viscous sheet, and then using a three-roll calender to press it into a flat sheet, and cooling and shaping it, and then using a punch and a die to punch out a flat sheet with a mesh structure. The disclosed patent technologies include GB1116181A.

[0003] Although the above disclosed technical methods can form mesh sheets, they also have the following disadvantages:

[0004] 1. The inner mold and the outer mold are rotated in opposite directions to form a diamond mesh, which is first formed into a tube and then pulled and cut. This method has the problem of forming irremovable creases on the surface of the mesh material, destroying the local mechanical structure of the mesh. In addition, the structure of this mesh is that the strands forming the mesh are formed by overlapping up and down, and the tensile strength is low, and it cannot withstand large radial and axial tension. Moreover, for high molecular polymer materials with low viscosity, such as PET, PA and other materials, the molten plastic will sag due to the weight of the material when it is from the mold outlet to the shaping tube, causing the molten mesh tube to deform and destroy the structure of the mesh. The mesh produced by this method has an uneven surface because the strands forming the mesh are overlapped up and down, and its application occasions are limited.

[0005] 2. The production method of rectangular mesh produced by the reciprocating motion of the mold and the cutter is also a method of first forming a tube and then pulling and cutting. This method also has the problem of forming irremovable creases on the surface of the mesh, destroying the local mechanical structure of the mesh. Moreover, for low-viscosity polymer materials such as PET, PA and other materials, the molten plastic will sag due to the weight of the material when it moves from the mold outlet to the shaping tube, causing the molten mesh tube to deform and destroy the structure of the mesh.

[0006] 3. The method of using a flat head three-roll calender to form a plate and then punching it into a mesh can form a mesh with smooth upper and lower surfaces, but the production equipment is relatively complicated, the equipment cost is high, the process steps are very numerous, and the holes cannot be punched or extruded at one time during stamping. Further heating and melting of the thinned area are required to form the mesh, and the production cost is high. In addition, due to the use of a punch die to punch holes, the raw materials in the punched holes are all scraps, resulting in a large waste of raw materials and serious energy waste. Summary of the invention

[0007] In order to simplify the production process of plastic mesh, solve the technical problems of reducing the production cost of plastic mesh and causing material waste, the present invention designs a molding device and method for producing a flat plastic mesh. The molding process of the plastic mesh can be realized through a one-step process, and at the same time, it can also ensure that the upper and lower surfaces of the plastic mesh after one-time molding are both flat, thereby simplifying the process.

[0008] The technical solution of the present invention is a molding device for producing a flat plastic mesh in one step, including a feeding mechanism, a molding mechanism, and a discharging traction mechanism. The key is: the molding mechanism includes a machine head provided with a material receiving port, a dispersion chamber, and a long strip slit lip, and a molding mold arranged at the slit lip, the molding mold includes a lip mold fixed at the slit lip, and a knife mold close to the slit lip, the knife mold has up and down reciprocating freedom with the help of a driving mechanism, the lip mold is a long strip with a smooth surface, and the knife mold is a toothed tool with a first groove and a first protrusion; or, the lip mold is a long strip with a second groove and a second protrusion on the surface, and the knife mold is a tool with a smooth cutting edge.

[0009] The feeding mechanism comprises an extruder, and the outlet of the extruder is sealedly connected to the material receiving port of the die head.

[0010] The discharging traction mechanism is a group of traction rollers arranged below the slit lip, and a cooling water jacket is arranged inside the traction rollers.

[0011] The rotation directions of two adjacent traction rollers in the traction roller group are opposite.

[0012] The molding equipment also includes a conveying mechanism for the final product.

[0013] A method for forming a flat plastic net using the above-mentioned forming equipment, the key of which is: the forming method uses the intermittent up and down movement of the knife die, with the help of a forming mold formed by protrusions and grooves, to control the molten raw material at the slit lip to flow out or not flow out according to the structure of the forming mold, thereby realizing a one-time forming process of the flat plastic net.

[0014] The intrinsic viscosity of the raw material in the molten state is set to 0.5-0.9 dL / g.

[0015] The temperature of the raw materials in the molten state is controlled at 170-210°C.

[0016] The molding method also includes a cooling and solidification process, in which the molded plastic net is pulled, cooled and solidified by a group of traction rollers with heat exchange cooling, forming a continuous solidification and conveying process.

[0017] The core technical solution of the present invention is to change the flow direction of the molten raw material at the slit lip by intermittently moving the knife die in the molding mold up and down, and utilize the tooth structure in the mold, that is, the convex part will block the flow direction of the raw material, while the groove can allow the raw material to flow out to realize the mesh forming process.

[0018] The beneficial effects of the present invention are:

[0019] 1. The molding equipment structure and molding control method of the present invention solve the problem that polymer raw materials with low viscosity cannot be used for direct production by extrusion.

[0020] 2. The molten raw materials can be formed into a flat grid-like plastic product in one step, which greatly simplifies the process and improves production efficiency. The flat plastic mesh product is a completely continuous product and can be cut arbitrarily according to needs later, solving the problem of creases that cannot be removed in the production of the public technical method. In addition, the product formed by the one-step method has no overlapping points and no stress concentration caused by punching, so the formed mesh has high tensile strength and enhanced tear resistance.

[0021] 3. In addition, the equipment and method can achieve zero waste of raw materials, and no punching scraps are generated during production, thus saving raw materials, saving energy, and reducing production costs.

[0022] 4. The upper and lower surfaces of the plastic mesh produced by the present invention are both flat, which solves the problem of uneven overlap of mesh ribs formed by the disclosed technical method, and provides convenience for the subsequent laminating process of non-woven fabrics or films.

[0023] 5. The design of adding a cooling water jacket to the traction roller can not only traction and convey the formed products, but also realize the cooling and solidification process during the traction process, which greatly reduces the process procedures and reduces the floor space of more equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the molding equipment of the present invention.

[0025] Figure 2 It is a schematic structural diagram of a flat plastic net produced by the molding equipment of the present invention.

[0026] Figure 3 It is a schematic diagram of a first embodiment of a knife die in the present invention.

[0027] Figure 4 yes Figure 3 Schematic cross-section of .

[0028] Figure 5 It is a schematic diagram of a first embodiment of the lip mold in the present invention.

[0029] Figure 6 yes Figure 5 Schematic cross-section of .

[0030] Figure 7 It is a schematic diagram of two embodiments of the knife die in the present invention.

[0031] Figure 8 yes Figure 7 Schematic cross-section of .

[0032] Fig. 9 It is a schematic diagram of a second embodiment of the lip mold in the present invention.

[0033] Fig.10 yes Fig. 9 Schematic cross-section of .

[0034] In the accompanying drawings, 1 is an extruder, 2 is a die head, 2-1 is a material receiving port, 2-2 is a dispersion chamber, 2-3 is a slit lip, 3-1 is a lip die, 3-2 is a knife die, 4 is a driving mechanism, 5-1 is a first groove, 5-2 is a first protrusion, 6-1 is a second groove, 6-2 is a second protrusion, 7 is a conveying mechanism, 8 is a flat plastic net, and 9 is a cooling water jacket. DETAILED DESCRIPTION

[0035] See also Figure 1, a one-step molding device for producing a flat plastic net, an extruder 1 is used to provide a head 2 with molten raw materials, the molten raw materials are dispersed into flat sheets in a dispersion chamber 2-2 in the head 2, a flat slit is set at the slit lip 2-3 of the head 2, and the molten raw materials flow out from the flat slit. A molding die with a groove and a convex structure is set outside the flat slit, the molding die includes a lip mold 3-1 fixed at the slit lip 2-3 and a knife mold 3-2 that can realize up and down reciprocating motion, and the knife mold 3-2 performs controllable up and down reciprocating motion with the help of a driving mechanism 4. The driving mechanism 4 can be a cylinder or a servo motor. When the knife die 3-2 is at the lower end of the reciprocating motion, the knife die 3-2 and the lip die 3-1 are tightly attached to each other, leaving only a row of holes to allow a portion of the molten raw materials to flow out, forming the longitudinal ribs of the flat plastic net 8; when the knife die 3-2 is at the upper end of the reciprocating motion, the knife die 3-2 and the lip die 3-1 are separated, and the molten raw materials will not be blocked by the structure formed between the two molds. All the raw materials can pass through the slit lip 2-3, thereby forming the transverse ribs of the flat plastic net 8. With such continuous reciprocating motion, a flat plastic net 8 with a mesh structure is formed at the die lip outlet of the flat die head, such as Figure 2 The up and down movement stroke of the knife die 3-2 can be adjusted according to the thickness of the flat plastic mesh 8. The maximum value is set for the gap height of the slit lip 2-3, and the thickness of the flat plastic mesh 8 is controlled by the upper end position of the knife die 3-2, for example, 2mm, 3mm, 5mm. Of course, a set of heads 2 with different internal heights of the slit lip 2-3 can also be designed, and they can be replaced as needed. This method can avoid other adverse effects caused by the knife die 3-2 contacting the material.

[0036] See also Figure 3-10 There are two ways to realize the forming mold.

[0037] See also Figure 3-6 , one is that the fixed lip mold 3-1 is a long strip with a smooth surface, and the knife mold 3-2 is designed as a toothed tool with a first groove 5-1 and a first protrusion 5-2, that is, the knife mold 3-2 is designed as a toothed structure. When the knife mold 3-2 moves to the lower end and is in close contact with the lip mold 3-1, the first protrusion 5-2 will block the way of the raw material, so that the raw material can only flow out from the position of the first groove 5-1, forming a longitudinal rib. The width of the first groove 5-1 is the width of the longitudinal rib, and the depth of the first groove 5-1 is the thickness of the longitudinal rib. A set of knife molds with different parameters can be made according to needs to meet the needs of users with different needs.

[0038] See also Figure 7-10, and secondly, the fixed lip mold is a long strip with a second groove 6-1 and a second protrusion 6-2 on the surface, while the knife mold 3-2 is designed as a tool with a smooth cutting edge, that is, the lip mold 3-1 is designed as a toothed structure. When the knife mold 3-2 moves to the lower end and is in close contact with the lip mold 3-1, the second protrusion 6-2 will block the way of the raw material, so that the raw material can only flow out from the position of the second groove 6-1, forming longitudinal ribs. The width of the second groove 6-1 is the width of the longitudinal rib, and the depth of the second groove 6-1 is the thickness of the longitudinal rib. A set of lip molds with different parameters can be made as needed to meet the needs of users with different needs. However, the transverse ribs and longitudinal ribs of the flat plastic net 8 processed in this way are not in the same plane, and will form a staggered and crossed grid.

[0039] In the specific molding method, it is necessary to comprehensively set the extrusion speed of the extruder 1, the characteristic viscosity of the molten raw material, the descending residence time of the knife die 3-2, and the ascending residence time of the knife die 3-2, and reasonably adjust the product parameters required by the user. This can be achieved by PLC setting and controlling the entire equipment.

[0040] The design of setting a cooling water jacket 9 inside the traction roller 5 allows the traction roller 5 to lift out the flat plastic net 8 attached thereto through rotation, and on the other hand, to achieve cooling and solidification directly during the traction and lifting process, so that a flat plastic mesh with a mesh structure can be continuously formed. Normal temperature water in the cooling water jacket 9 enters from one end and exits from the other end, and the pipeline passing through the middle takes away the heat of the flat plastic net 8. Because the temperature of the flat plastic net 8 must be at least above 150°C when it is just formed, the purpose of cooling is mainly to prevent the flat plastic net 8 from sticking to the traction roller 5. Of course, some anti-sticking layers will also be applied to the outer surface of the traction roller 5. After one level of cooling, the temperature of the flat plastic net 8 can be reduced to below 100°C, and after two or three levels of cooling, it can be cooled to 30°C, and then naturally cooled to room temperature through the subsequent conveying mechanism 7 for cutting and packaging.

[0041] The adjacent traction rollers 5 rotate in opposite directions, which can make the produced flat plastic net 8 more evenly stressed and cooled. Both the upper and lower surfaces will be cooled and pulled. Only by cooling and pulling at the same time can the uniformity of stress on the flat plastic net 8 be guaranteed. Otherwise, under high temperature conditions, the net is likely to be broken or deformed, resulting in a significant reduction in the yield rate.

Claims

1. A one-step molding device for producing a flat plastic net, comprising a feeding mechanism, a molding mechanism, and a discharging traction mechanism, characterized in that: The molding mechanism comprises a machine head (2) provided with a material receiving port (2-1), a dispersion chamber (2-2), a long strip slit lip (2-3), and a molding die arranged at the slit lip (2-3); the molding die comprises a lip die (3-1) fixed at the slit lip (2-3), and a knife die (3-2) close to the slit lip (2-3); the knife die (3-2) has up and down reciprocating freedom with the help of a driving mechanism (4); the lip die (3-1) is in the shape of a long strip with a smooth surface, and the knife die (3-2) is a toothed tool with a first groove (5-1) and a first protrusion (5-2); or, the lip die (3-1) is in the shape of a long strip with a second groove (6-1) and a second protrusion (6-2) on the surface, and the knife die (3-2) is a tool with a smooth cutting edge.

2. The one-step forming device for producing a flat plastic net according to claim 1, characterized in that: The feeding mechanism comprises an extruder (1), the outlet of the extruder (1) being sealedly connected to a material receiving port (2-1) of a die head (2).

3. The one-step forming device for producing a flat plastic net according to claim 1, characterized in that: The discharging traction mechanism is a group of traction rollers (5) arranged below the slit lip (2-3), and a cooling water jacket (9) is arranged inside the traction rollers (5).

4. The one-step forming device for producing a flat plastic net according to claim 3, characterized in that: The rotation directions of two adjacent traction rollers (5) in the traction roller (5) group are opposite.

5. The one-step forming device for producing a flat plastic net according to claim 1, characterized in that: The molding device also includes a conveying mechanism (7) for the final product.

6. A method for forming a flat plastic net using the forming device according to claim 1, characterized in that: The molding method controls the molten raw material at the slit lip (2-3) to flow out or not flow out according to the structure of the molding die through the intermittent up and down movement of the knife die, with the help of the molding die formed by the protrusions and grooves, so as to realize the one-step molding process of the flat plastic net.

7. The method for forming a flat plastic net according to claim 6, characterized in that: The intrinsic viscosity of the raw material in the molten state is set to 0.5-0.9 dL / g.

8. The method for forming a flat plastic net according to claim 6, characterized in that: The temperature of the raw materials in the molten state is controlled at 170-210°C.

9. The method for forming a flat plastic net according to claim 6, characterized in that: The molding method also includes a cooling and solidification process, in which the molded plastic net is pulled, cooled, and solidified by a group of traction rollers (5) with heat exchange cooling, thereby forming a continuous solidification and conveying process.

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