Screen forming process based on TPU (thermoplastic polyurethane) dispensing welding and screen thereof

Abstract

The invention relates to the field of macromolecular composite thermoplastic materials, and discloses a screen forming process based on TPU dispensing welding and a screen thereof. The screen forming process based on TPU dispensing welding comprises the steps that butt joint edges of two TPU screen sub-pieces are aligned and close to each other, so that a gap is formed between the two TPU screen sub-pieces; the two butt joint edges corresponding to the gaps are preheated, and the temperature after preheating is lower than the melting temperature of the TPU screen cloth sub-pieces; the preheated gap is filled with TPU in the molten state in a dispensing mode, cooling and shaping are conducted, and a screen assembly is formed; and the remaining TPU screen sub-pieces and the screen assembly formed in the last time are subjected to adhesive dispensing welding in sequence, and a screen forming piece is obtained. The screen forming part prepared by the invention has excellent impact resistance, tear resistance, tensile resistance and the like.

Description

Technical Field

[0001] The invention relates to the field of macromolecular composite thermoplastic materials, and in particular to a screen forming process based on TPU glue spot welding and a screen. Background Art

[0002] Thermoplastic polyurethane (TPU) has good wear resistance, low temperature resistance, aging resistance, mildew resistance, high-strength impact resistance, tear resistance, high elongation and tensile strength, etc. It is widely used in shoemaking, toys, automobiles, sports, medical, mineral processing and other industries.

[0003] Injection molding is the most commonly used TPU molding process. The function of injection molding is to process TPU into the required parts, including pre-molding, injection and extrusion. After the product is formed, if it needs to be injected again, the original part can be placed in the mold and injected again.

[0004] Due to factors such as injection molding machines, molds and sites, large screen mesh parts are usually welded by small-sized injection molding to form large-sized screen meshes of required specifications. The existing welding method uses glue welding, and the strength of the formed screen mesh parts is low. It is suitable for occasions with low strength requirements, but it is difficult to meet the use requirements of the mineral processing industry. Summary of the invention

[0005] The main purpose of the present invention is to provide a screen forming process based on TPU spot welding and a screen thereof, aiming to solve the problem of low strength of the TPU molded screen made by the existing welding method.

[0006] To achieve the above object, the present invention proposes a screen forming process based on TPU dispensing welding, comprising the following steps:

[0007] S10, providing at least two TPU screen components;

[0008] S20, taking two TPU mesh components, and aligning the butting edges of the two TPU mesh components so as to form a gap between the two TPU mesh components;

[0009] S30, preheating the two butt joint edges corresponding to the gap, wherein the temperature after preheating is close to but lower than the melting temperature of the TPU mesh component, so that the two butt joint edges are in a softened but non-molten state;

[0010] S40, using a dispensing method to fill the molten TPU into the preheated gap, cooling and shaping, and forming a screen assembly;

[0011] S50, sequentially dispensing and welding the remaining TPU screen components with the screen assembly formed last time according to the method of steps S20 to S40 to obtain a screen molded part.

[0012] Optionally, in step S30, the melting temperature of the TPU mesh component is 190-210°C, and the temperature of the two butting edges after preheating is T, T<190°C.

[0013] Preferably, 180°C ≤ T ≤ 187°C.

[0014] Optionally, in step S30, the two butting edges are preheated by laser infrared heating, high frequency heating, or hot air heating.

[0015] Optionally, in step S20, the width s of the gap is 0.5-5.0 mm.

[0016] Optionally, in step S40, a dispensing head is used to continuously dispense glue along the length direction of the gap, and the dispensing amount is 10 to 500 mL / min.

[0017] Preferably, the dispensing amount is 100 to 300 mL / min.

[0018] Optionally, in step S20, the butt joint edge includes a groove surface and a blunt edge located below the groove surface.

[0019] Optionally, the height p of the blunt edge does not exceed 1 mm, and the groove surface angle α is 15 to 45°.

[0020] Preferably, the groove surface angle α is 10 to 30°.

[0021] Optionally, in step S30, the two butting edges are preheated section by section along the length direction of the gap.

[0022] Optionally, in step S10, a plurality of TPU screen components are formed by injection molding; and / or,

[0023] The raw materials of the TPU screen components in step S10 and the molten TPU in step S40 both include polyether TPU.

[0024] The present invention also provides a screen mesh, which is manufactured by using any of the above-mentioned screen mesh forming processes based on TPU dispensing welding.

[0025] The technical solution of the present invention adopts a method of preheating the butt joint edge so that the butt joint edge of the screen is in a softened state while basically maintaining the original structure, but not in a molten state, that is, it has no fluidity, so as to ensure stable and reliable connection with the welding material. Molten TPU is used as the welding material, and the material of the welding material is the same as that of the screen, and the welding is performed by dispensing glue, so that the welding material can fully penetrate into the structure of the butt joint edge to form a stable overall structure, thereby ensuring the strength and quality reliability of the obtained screen molding, and can better meet the needs of the mineral processing industry. The technical solution of the present invention is also suitable for welding screens with irregular butt joint edges.

[0026] The screen mesh molded parts produced by the present invention have excellent impact resistance, tear resistance, and tensile resistance. The large screen mesh produced by the present invention is widely used in mineral processing operations. The screen meshes generally used in large-scale steel enterprises have a service life of more than 8 months. After tracking for more than one year, there are almost no failure cases. In addition, the analysis of the failed screen mesh shows that the failure site is not the weld seam, but when the equipment has an occasional overload failure, the mesh area of ​​the screen mesh is damaged and fails due to overload or the mesh exceeds the set value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0028] Figure 1 A schematic diagram of the process flow of the screen mesh forming process based on TPU dispensing welding provided by the present invention;

[0029] Figure 2 A schematic diagram of the top view of the structure of the TPU screen mesh components provided by the present invention being subjected to glue spot welding;

[0030] Figure 3 A schematic diagram of the structure of the TPU screen component provided by the present invention having a groove surface;

[0031] Figure 4 For Figure 3 A schematic diagram of the structure of preheating and dispensing glue in the gap formed by the TPU screen components;

[0032] Figure 5 It is a structural schematic diagram of the heating device and the dispensing head moving along the length direction of the gap.

[0033] Description of Figure Numbers:

[0034] 1. TPU screen parts; 11. Butt edge; 111. Bevel surface; 112. Blunt edge; 12. Gap; 2. Screen assembly; 21. Welding material; 3. Screen forming part; 4. Heating device; 5. Glue dispensing head.

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] See also Figures 1 to 5 In the present invention, a screen forming process based on TPU dispensing welding includes the following steps:

[0040] S10, providing at least two TPU screen components 1;

[0041] S20, taking two TPU mesh components 1, and aligning the butting edges 11 of the two TPU mesh components 1 so as to form a gap 12 between the two TPU mesh components 1;

[0042] S30, preheating the two butt joint edges 11 corresponding to the gap 12, wherein the temperature after preheating is close to but lower than the melting temperature of the TPU mesh component 1, so that the two butt joint edges 11 are in a softened but non-molten state;

[0043] S40, filling the molten TPU into the preheated gap 12 by dispensing, and cooling and shaping to form the screen assembly 2;

[0044] S50 , sequentially weld the remaining TPU screen components 1 with the screen assembly 2 formed last time by glue spot welding according to the method of steps S20 to S40 to obtain the screen molded part 3 .

[0045] In the technical solution of the present invention, a plurality of small-sized TPU mesh components 1 are prepared, and two TPU mesh components 1 are placed on a workbench so that the butt edges 11 of the two TPU mesh components 1 are aligned and close to each other but not fitted, and a gap 12 is left between the two. The two butt edges 11 corresponding to the gap 12 are preheated by a heating device 4, and the temperature of the two butt edges 11 after preheating is lower than but close to the melting temperature of the TPU mesh component 1, so that the two butt edges 11 are in a softened state, but not in a molten state. At this time, the two butt edges 11 basically maintain the original structure. After preheating, the molten TPU is dripped into the gap 12 by dispensing. Since the molten TPU has good fluidity, it can better fill the gap 12 and contact with the butt edges 11. Since the butt joint 11 is in a softened state at this time, and the molten TPU is made of the same material as the screen, the molten TPU can penetrate into the structure of the butt joint 11 more fully, so that the welding material 21 is more stably connected to the original screen and forms an integral structure. The formed screen molding has a higher strength and can better meet the needs of the mineral processing industry.

[0046] The technical solution of the present invention adopts the method of preheating the butt joint 11, so that the butt joint 11 of the screen is in a softened state while basically maintaining the original structure, but it does not have fluidity, so as to ensure stable and reliable connection with the solder 21. Molten TPU is used as the solder 21, the material of the solder 21 is the same as that of the screen, and the solder 21 is welded by dispensing, so that the solder 21 can fully penetrate into the structure of the butt joint 11 softened after preheating, forming a stable overall structure, and ensuring the strength of the prepared screen molded part 3.

[0047] It should be noted that in step S10, a plurality of small-sized TPU mesh components 1 are formed by injection molding, and the raw material for preparing the TPU mesh components 1 is polyether TPU; in step S40, the raw material of the molten TPU is also polyether TPU. That is, the material of the TPU mesh components 1 is the same as the material of the welding material 21 (molten TPU) to ensure the welding effect. After the two butt joint edges 11 of the gap 12 are preheated, the glue spot welding needs to be carried out in time to avoid too long a time, which will cause the temperature of the butt joint edges 11 after preheating to drop significantly, reduce the softening degree, and affect the welding effect.

[0048] Furthermore, in the step S30, the melting temperature of the TPU mesh component 1 is 190-210°C, and the temperature of the two butt joint edges 11 after preheating is T, T<190°C. Preferably, 180°C≤T≤187°C, and the welding effect can be effectively guaranteed by controlling the temperature of the butt joint edge 11 after preheating within a specific range. It is understandable that if the temperature after preheating is too low, the softening degree of the butt joint edge 11 is low, which affects the penetration effect of the solder 21; if the temperature after preheating is too high, it is easy to cause the butt joint edge 11 to have fluidity, so that the structure of the butt joint edge 11 changes, and the welding effect is uncontrollable.

[0049] Specifically, in step S30, the two butt edges 11 are preheated by laser infrared heating, high frequency heating, or hot air heating. Preferably, the two butt edges 11 are preheated by hot air, and during preheating, the corresponding heating device 4 is located above the gap 12, and the air outlet faces the gap 12, so as to fully preheat the butt edges 11 to a specific temperature.

[0050] Furthermore, in the step S20, the width s of the gap 12 is 0.5-3.0 mm.

[0051] Specifically, the dispensing head 5 is used to continuously dispense glue along the length direction of the gap, and the dispensing amount is 10-500 mL / min. The solder 21 is dripped into the gap 12 by the continuous dispensing method, thereby ensuring the welding effect.

[0052] It can be understood that in the step S30, the heating device 4 is used to preheat the two butt joints 11, and the heating device 4 and the glue dispensing head 5 both move along the length direction of the gap 12, and the glue dispensing head 5 is located behind the heating device 4. The heating device 4 first preheats a corresponding section of the butt joint 11 in the gap 12. After preheating to a predetermined temperature so that the butt joint 11 of this section is softened, the heating device 4 continues to move forward to preheat the next section of the butt joint 11, and the glue dispensing head 5 also moves forward to promptly drip the solder 21 into the preheated gap 12, so that the solder 21 contacts the softened butt joint 11 of the previous section after preheating, and repeats this process until the solder 21 fills the entire gap 12.

[0053] Furthermore, in the step S20, the butt edge 11 includes a groove surface 111 and a blunt edge 112 located below the groove surface 111. After the two butt edges 11 are aligned and close to each other, the gap 12 formed is in a "Y" shape, which helps the welding material 21 to spread quickly in the gap 12, thereby improving the connection effect between the welding material 21 and the butt edge 11 and improving the strength of the obtained screen molding.

[0054] Specifically, the height p of the blunt edge 112 does not exceed 1 mm, and the angle α of the groove surface 111 is 15 to 45 degrees.

[0055] The present invention also proposes a screen, which is made by the above-mentioned screen forming process based on TPU dispensing welding. Since this screen adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0056] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0057] Example 1

[0058] A screen forming process based on TPU dispensing welding includes the following steps:

[0059] S10. Use a mold to injection mold polyether TPU (Meirui New Material M88, melting temperature 190-195° C.) to form 5 TPU screen components 1, wherein the thickness d of each TPU screen component 1 is 5 mm, and the butt edge 11 of each TPU screen component 1 is rectangular.

[0060] S20, taking two TPU mesh components 1, and aligning the butting edges 11 of the two TPU mesh components 1 so as to form a gap 12 between the two TPU mesh components 1; wherein the width s of the gap 12 is 1 mm;

[0061] S30. At room temperature (25°C), the hot blowing device first preheats a corresponding section of the butt edge 11 in the gap 12. After preheating to 180°C to soften the butt edge 11 of this section, the hot blowing device moves forward to preheat the butt edge 11 of the next section, and the dispensing head 5 located behind the hot blowing device also moves forward to promptly drip the solder 21, that is, the molten polyether TPU (Meirui New Material M88) into the preheated gap 12, so that the solder 21 contacts with the butt edge 11 softened after the previous preheating, and repeats this process until the solder 21 fills the entire gap 12, and cools and shapes to form the screen assembly 2; wherein, the caliber of the dispensing head 5 is 1 mm, the distance h between the dispensing head 5 and the feed end of the gap 12 is 1.0 mm, and the dispensing amount is 200 mL / min.

[0062] S40, welding the remaining TPU screen components 1 with the screen assembly 2 formed last time in sequence according to the method of steps S20 to S30 to obtain the screen molded part 3.

[0063] Embodiments 2 to 4

[0064] Embodiments 2 to 4 are based on embodiment 1, and the difference between them is that in step S30, the preheated temperatures of the butt joint edges on both sides of the gap are different, and the rest remain the same as embodiment 1.

[0065] Embodiment 2: In step S30, the butt joint edges on both sides of the gap are preheated to 176°C.

[0066] Embodiment 3: In step S30, the butt joint edges on both sides of the gap are preheated to 185°C.

[0067] Embodiment 4: In step S30, the butt joint edges on both sides of the gap are preheated to 187°C.

[0068] Example 5

[0069] This embodiment is based on the embodiment 3, and the difference is that: in step S10, the butt edge includes a groove surface and a blunt edge located below the groove surface, wherein the groove surface angle α is 25°, and the height p of the blunt edge is 0.5 mm; in step S20, the distance s1 between the two blunt edges corresponding to the gap is 0.3 mm; the rest remains the same as the embodiment 3.

[0070] Comparative Example 1

[0071] This comparative example is based on Example 1, and the difference is that in step S30, the butt joint edges on both sides of the gap are preheated to 170°C, and the rest is the same as Example 1.

[0072] Comparative Example 2

[0073] This comparative example is based on Example 1, and the difference is that in step S30, the butt joint edges on both sides of the gap are preheated to 192°C, so that the two butt joint edges corresponding to the gap are in a molten state, and the rest remains the same as Example 1.

[0074] Performance Testing

[0075] The screen forming parts prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were subjected to a tensile strength test according to the method of GB / T 1040-1992, wherein the sample thickness was 5 mm and the width was 10 mm. Six samples were taken from each experimental group, and the experimental results were averaged. The results of each experimental group are shown in Table 1 below.

[0076] Table 1 Tensile strength of screen moldings of each experimental group (MPa)

[0077] Tensile strength(MPa) Example 1 31.8 Example 2 29.4 Example 3 32.5 Example 4 32.6 Example 5 33.1 Comparative Example 1 27.3 Comparative Example 2 28.5

[0078] From the test results in Table 1, it can be seen that the screen mesh molded part prepared by the present invention has better tensile strength and can better meet the use requirements. However, in Comparative Example 1 and Comparative Example 2, the strength of the screen mesh molded part is affected due to the too low or too high temperature after preheating.

[0079] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A screen forming process based on TPU dispensing welding, characterized in that: The following steps are involved: S10, providing at least two TPU screen components; S20, taking two TPU mesh components, and aligning the butting edges of the two TPU mesh components so as to form a gap between the two TPU mesh components; S30, preheating the two butt joint edges corresponding to the gap, wherein the temperature after preheating is close to but lower than the melting temperature of the TPU mesh component, so that the two butt joint edges are in a softened but non-molten state; S40, using a dispensing method to fill the molten TPU into the preheated gap, cooling and shaping, and forming a screen assembly; S50, sequentially dispensing and welding the remaining TPU screen components with the screen assembly formed last time according to the method of steps S20 to S40 to obtain a screen molded part.

2. The screen forming process based on TPU dispensing welding according to claim 1 is characterized in that: In the step S30, the melting temperature of the TPU mesh component is 190-210°C, and the temperature of the two butting edges after preheating is T, T<190°C.

3. The screen forming process based on TPU dispensing welding as claimed in claim 2, characterized in that: In the step S30, the two butting edges are preheated by laser infrared heating, high frequency heating, or hot air heating.

4. The screen forming process based on TPU dispensing welding according to claim 1 is characterized in that: In the step S20, the width s of the gap is 0.5-5.0 mm.

5. The screen forming process based on TPU dispensing welding as claimed in claim 4, characterized in that: In the step S40, a dispensing head is used to continuously dispense glue along the length direction of the gap, and the dispensing amount is 10 to 500 mL / min.

6. The screen forming process based on TPU dispensing welding as claimed in claim 5, characterized in that: In the step S20, the butt joint edge includes a groove surface and a blunt edge located below the groove surface.

7. The screen forming process based on TPU dispensing welding as claimed in claim 6, characterized in that: The height p of the blunt edge does not exceed 1 mm, and the angle α of the groove surface is 15 to 45°.

8. The screen forming process based on TPU dispensing welding as claimed in claim 5, characterized in that: In the step S30, the two butting edges are preheated section by section along the length direction of the gap.

9. The screen forming process based on TPU dispensing welding according to claim 1, characterized in that: In the step S10, a plurality of TPU mesh components are formed by injection molding; and / or, The raw materials of the TPU screen components in step S10 and the molten TPU in step S40 both include polyether TPU.

10. A screen, characterized in that: The screen is manufactured by using the screen forming process based on TPU dispensing welding as described in any one of claims 1 to 9.

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