Polyurethane and rubber composite mine screen and method of making same

Abstract

The present application relates to the field of mine screening, discloses a polyurethane and rubber composite mine screen and a preparation method thereof; the screen comprises a screen body and a screen hole; the screen body comprises, from the working surface to the back surface, a polyurethane wear-resistant layer, an interface transition layer and a rubber elastic layer; the rubber elastic layer is provided with an inverted locking groove with a groove width smaller than a groove bottom width around the screen hole; the polyurethane wear-resistant layer has a polyurethane anchoring column extending into the inverted locking groove; and the interface transition layer is distributed between the inner wall of the inverted locking groove and the polyurethane anchoring column. The upper opening of the screen hole is formed with a wear-resistant lip by the polyurethane wear-resistant layer, the lower opening of the screen hole is formed with a rubber lower opening edge by the rubber elastic layer, and the outer side of the rubber lower opening edge is provided with a pressure relief groove in communication with the lower opening of the screen hole and not penetrating through the polyurethane wear-resistant layer. The preparation method comprises the steps of preforming the rubber elastic layer, pre-vulcanizing, surface treatment, transition material coating, polyurethane pouring and composite curing.

Description

Technical Field

[0001] This invention relates to the field of mine screening, specifically to polyurethane and rubber composite mine screens and their preparation methods. Background Technology

[0002] Mining screening equipment typically uses screens to classify crushed ore, washed ore, tailings slurry, and muddy mineral powder by particle size. During use, the screens are simultaneously subjected to the impact and friction of ore particles, the periodic bending caused by the vibration of the screening machine, and the adhesion of water-containing fine materials to the edges of the screen holes. Its structural stability directly affects the continuity of screening.

[0003] Existing mine screens mostly use metal screens, polyurethane screens, rubber screens, or polyurethane and rubber composite screens. Metal screens are impact-resistant but generate more noise and wear; polyurethane screens have good wear resistance, but their elastic deformation ability at the screen hole edges is limited; rubber screens have good resilience, but the working face is easily worn when subjected to sharp-angled ore. Some composite screens improve overall strength through adhesive bonding, fabric reinforcement, or layer bonding.

[0004] However, under the combined effects of high abrasion, strong vibration, and wet, sticky materials, the edges of the screen openings often become the concentrated location of failure. In existing composite screens, the polyurethane layer and rubber layer are mostly planarly bonded, and the perimeter of the screen openings lacks embedded constraints against interlayer shear and edge bending. At the same time, the lower opening of the screen openings lacks independent deformation space, and wet, sticky fine materials are easily trapped at the edge of the openings, leading to a superposition of problems such as clogging, increased wear at the opening openings, and interlayer delamination. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a polyurethane and rubber composite mining screen and its preparation method to solve the technical problems existing in the prior art.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A polyurethane and rubber composite mining screen, a screen body and screen holes provided on the screen body, characterized in that the screen body includes a polyurethane wear-resistant layer, an interface transition layer and a rubber elastic layer arranged sequentially from the working surface to the back surface. The rubber elastic layer has an inverted locking groove on the side facing the polyurethane wear-resistant layer and around the screen holes. The width of the groove opening is smaller than the width of the groove bottom. The polyurethane wear-resistant layer has polyurethane anchor columns that extend into the inverted locking groove. The polyurethane anchor columns are integrally formed with the polyurethane wear-resistant layer and are filled in the inverted locking groove. The interface transition layer is distributed between the inner wall of the inverted locking groove and the polyurethane anchor post, and extends to the surface of the rubber elastic layer facing the polyurethane wear-resistant layer. The sieve holes penetrate the polyurethane wear-resistant layer, the interface transition layer, and the rubber elastic layer. The upper opening of the sieve holes is formed by the polyurethane wear-resistant layer to form a wear-resistant lip, and the lower opening of the sieve holes is formed by the rubber elastic layer to form a rubber lower opening edge. The rubber elastic layer has a pressure relief groove on the side of the rubber lower opening edge away from the sieve holes, which is connected to the lower opening of the sieve holes. The pressure relief groove is located inside the rubber elastic layer and is spaced apart from the polyurethane wear-resistant layer.

[0007] Preferably, the inverted locking groove is located in the annular locking area around the sieve hole, and the distance between the inner edge of the annular locking area and the wall of the sieve hole is 1.5mm to 6mm; four or more inverted locking grooves are provided in the annular locking area corresponding to each sieve hole, and the center distance between two adjacent inverted locking grooves is 3mm to 12mm.

[0008] Preferably, the inverted locking grooves are arranged intermittently along the circumference of the screen holes, and a continuous rubber bridge is formed between two adjacent inverted locking grooves. The width of the continuous rubber bridge is 1mm to 5mm. The width of the inverted locking groove is 50% to 85% of the bottom width, and the depth of the inverted locking groove is 10% to 35% of the thickness of the rubber elastic layer.

[0009] Preferably, the interface transition layer is formed by curing a transition material, which includes an isocyanate-terminated polyurethane prepolymer and activated rubber powder; By weight, the activated rubber powder is 5 to 25 parts relative to 100 parts of isocyanate-terminated polyurethane prepolymer, and the particle size of the activated rubber powder is 80 to 200 mesh.

[0010] Preferably, the wear-resistant lip is continuously provided along the upper opening of the screen hole, and the upper edge of the wear-resistant lip is a rounded edge with a radius of 0.5mm to 3mm. The lower edge of the rubber is continuously arranged along the lower opening of the sieve hole. The depth of the pressure relief groove is 15% to 40% of the thickness of the rubber elastic layer. There is a rubber spacer between the bottom of the pressure relief groove and the polyurethane wear-resistant layer. The thickness of the rubber spacer is 0.5mm to 5mm.

[0011] Preferably, the Shore A hardness of the polyurethane wear-resistant layer is 85 to 95, the Shore A hardness of the rubber elastic layer is 55 to 75, and the thickness of the polyurethane wear-resistant layer is 30% to 70% of the thickness of the rubber elastic layer.

[0012] A method for preparing polyurethane and rubber composite mining screens includes the following steps: To prepare the rubber elastic layer, the rubber compound is placed into the molding mold, so that the rubber elastic layer forms the lower opening of the sieve hole, the edge of the rubber lower opening, the pressure relief groove, and the inverted locking groove located around the sieve hole. The rubber elastic layer is then pre-vulcanized. The pre-vulcanized rubber elastic layer is surface treated to form an activated surface on the side of the rubber elastic layer facing the polyurethane wear-resistant layer, the inner wall of the inverted locking groove, and the lower edge of the sieve hole. A transition material is applied to the inner wall of the inverted locking groove and the surface of the rubber elastic layer facing the polyurethane wear-resistant layer to form an interface transition layer. Polyurethane casting material is poured into the mold containing the rubber elastic layer, so that the polyurethane casting material covers the side of the rubber elastic layer facing the polyurethane wear-resistant layer and enters the inverted locking groove to form a polyurethane anchor column, while a wear-resistant lip is formed at the top of the screen hole. The mold is heat-insulated and cured to form a composite polyurethane wear-resistant layer, interface transition layer and rubber elastic layer. After demolding, a polyurethane and rubber composite mining screen is obtained.

[0013] Preferably, when preparing the rubber elastic layer, the rubber compound is pre-vulcanized in the molding die for a pre-vulcanization time of 50% to 75% of t90, where t90 is the positive vulcanization time of the rubber compound measured at the pre-vulcanization temperature; the pre-vulcanized rubber elastic layer retains the molding contours of the sieve opening, the rubber opening edge, the pressure relief groove, and the inverted locking groove.

[0014] Preferably, when performing surface treatment on the pre-vulcanized rubber elastic layer, the side of the rubber elastic layer facing the polyurethane wear-resistant layer, the inner wall of the inverted locking groove, and the lower edge of the sieve hole are sequentially polished, cleaned, and plasma treated; the surface roughness Ra after polishing is 6.3 μm to 25 μm, the plasma treatment power is 100 W to 300 W, and the treatment time is 30 s to 180 s.

[0015] Preferably, before casting the polyurethane castable, the polyurethane castable is vacuum degassed. The gauge pressure during vacuum degassed is -0.08MPa to -0.10MPa, and the degassed time is 5min to 15min. After pouring, keep it at 80℃ to 110℃ for 2 to 5 hours to cure. After demolding, allow it to mature at 90℃ to 120℃ for 6 to 16 hours.

[0016] In summary, the present invention has the following main beneficial effects: This application achieves the effect of the polyurethane wear-resistant layer directly bearing the impact, friction, and cutting action of ore particles by placing a polyurethane wear-resistant layer on one side of the working surface of the screen body and forming a continuous wear-resistant lip at the upper opening of the screen holes. Simultaneously, by placing a rubber elastic layer on one side of the back of the screen body and forming a rubber lower edge at the lower opening of the screen holes, the rubber elastic layer provides local elastic support during screen vibration. This structure allows the upper and lower openings of the screen holes to bear the stress under different working conditions, avoiding the problem of difficulty in balancing wear resistance and elastic deformation capacity in single-material screens.

[0017] This application achieves an embedded connection of the polyurethane wear-resistant layer around the screen holes by setting an inverted locking groove on the side of the rubber elastic layer facing the polyurethane wear-resistant layer and around the screen holes, and by making the polyurethane wear-resistant layer form a polyurethane anchor column extending into the inverted locking groove. Simultaneously, by setting an interface transition layer between the inner wall of the inverted locking groove and the polyurethane anchor column, a material transition and groove filling effect is achieved between the rubber elastic layer and the polyurethane wear-resistant layer. Therefore, the interlayer connection at the edge of the screen holes no longer relies solely on planar adhesive or ordinary bonding, reducing the risk of interlayer peeling around the screen holes under the impact, vibration, and bending effects of mining screening.

[0018] This application achieves the effect of providing local deformation space for the rubber area at the bottom of the screen opening by setting a pressure relief groove on the side of the rubber opening away from the screen opening, and positioning the pressure relief groove within the rubber elastic layer and spaced apart from the polyurethane wear-resistant layer. This maintains the stability of the polyurethane wear-resistant lip at the top of the screen opening while providing local deformation space for the rubber area at the bottom of the screen opening. When screening water-containing mineral powder, mud-containing mineral material, or tailings slurry, the rubber material at the bottom of the screen opening can undergo local deformation with the vibration of the screen, making it easier to loosen the wet and sticky particles embedded near the bottom of the screen opening, thereby reducing the impact of screen blockage and material accumulation at the edge of the opening on continuous screening. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the main structure of the present invention; Figure 3 This is a partial cross-sectional structural schematic diagram of the present invention; Figure 4 This is a schematic diagram of a partial separation structure of the present invention.

[0020] In the figure: 1: Polyurethane wear-resistant layer; 2: Rubber elastic layer; 3: Screen hole; 4: Wear-resistant lip; 5: Polyurethane anchor post; 6: Inverted locking groove; 7: Annular locking area; 8: Pressure relief groove; 10: Rubber spacer layer; 11: Interface transition layer; 12: Rubber continuous bridge. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] refer to Figure 1A dynamic target detection method based on three-dimensional low-altitude surveillance radar includes a screen body and screen holes disposed on the screen body. The screen body is characterized in that it includes a polyurethane wear-resistant layer, an interface transition layer and a rubber elastic layer disposed sequentially from the working surface to the back surface. The rubber elastic layer has an inverted locking groove on the side facing the polyurethane wear-resistant layer and around the screen holes. The width of the groove opening is smaller than the width of the groove bottom. The polyurethane wear-resistant layer has polyurethane anchor columns that extend into the inverted locking groove. The polyurethane anchor columns are integrally formed with the polyurethane wear-resistant layer and are filled in the inverted locking groove. The interface transition layer is distributed between the inner wall of the inverted locking groove and the polyurethane anchor post, and extends to the surface of the rubber elastic layer facing the polyurethane wear-resistant layer. The sieve holes penetrate the polyurethane wear-resistant layer, the interface transition layer, and the rubber elastic layer. The upper opening of the sieve holes is formed by the polyurethane wear-resistant layer to form a wear-resistant lip, and the lower opening of the sieve holes is formed by the rubber elastic layer to form a rubber lower opening edge. The rubber elastic layer has a pressure relief groove on the side of the rubber lower opening edge away from the sieve holes, which is connected to the lower opening of the sieve holes. The pressure relief groove is located inside the rubber elastic layer and is spaced apart from the polyurethane wear-resistant layer.

[0023] The polyurethane and rubber composite mining screen of this application is used in vibrating screens, tension screens, or modular mining screening equipment for screening crushed ore, washed ore, tailings slurry, water-containing mineral powder, and mud-containing ore. During use, the side of the screen body that directly bears the impact and friction of ore particles is the working surface, and the side facing away from the working surface is the back surface. The upper opening of the screen hole refers to the opening located on the working surface side, and the lower opening of the screen hole refers to the opening located on the back surface side.

[0024] The polyurethane wear-resistant layer, interface transition layer, and rubber elastic layer described in this application are a composite layer structure formed sequentially along the thickness direction of the screen body. The polyurethane wear-resistant layer is located on one side of the working surface, the rubber elastic layer is located on the back side, and the interface transition layer is located between the polyurethane wear-resistant layer and the rubber elastic layer. The screen holes penetrate the polyurethane wear-resistant layer, the interface transition layer, and the rubber elastic layer, allowing the screened material to enter through the upper opening of the screen holes and exit through the lower opening.

[0025] Example 1: Overall Structure of Polyurethane and Rubber Composite Mining Screen This embodiment provides a polyurethane and rubber composite mining screen, including a screen body and screen holes disposed on the screen body. The screen body has a plate-shaped screen surface structure, and the screen holes are arranged on the screen body according to the required screening particle size. When the screen holes adopt an elongated hole structure, the length direction of the screen holes is arranged along the material movement direction; when the screen holes adopt a rectangular hole structure, the long side direction of the screen holes is consistent with the installation direction of the screen body. The specific hole diameter is determined according to the target screening particle size of the mining screening equipment.

[0026] The screen body comprises a polyurethane wear-resistant layer, an interface transition layer, and a rubber elastic layer, arranged sequentially from the working surface to the back surface. The polyurethane wear-resistant layer is located on one side of the working surface of the screen and forms the upper opening area of ​​the screen holes. The rubber elastic layer is located on one side of the back surface of the screen and forms the lower opening area of ​​the screen holes. The interface transition layer is located between the polyurethane wear-resistant layer and the rubber elastic layer and enters the inverted locking groove described later.

[0027] An inverted locking groove is provided on the side of the rubber elastic layer facing the polyurethane wear-resistant layer and around the screen holes. The width of the groove opening is smaller than the width of the groove bottom. The groove opening width refers to the width of the opening of the inverted locking groove on the side closest to the polyurethane wear-resistant layer, and the groove bottom width refers to the width of the bottom area of ​​the inverted locking groove on the side furthest from the polyurethane wear-resistant layer. Both the groove opening width and the groove bottom width are measured in a direction parallel to the screen body surface. Because the groove opening width is smaller than the groove bottom width, the inverted locking groove forms a groove structure that is wider inside and narrower outside.

[0028] The polyurethane wear-resistant layer has polyurethane anchor posts extending into the inverted locking groove. The polyurethane anchor posts are integrally molded with the polyurethane wear-resistant layer and fill the inverted locking groove. During preparation, polyurethane casting covers the side of the rubber elastic layer facing the polyurethane wear-resistant layer and enters the inverted locking groove; after the polyurethane casting has cured, the portion within the inverted locking groove forms the polyurethane anchor posts, and the portion above the rubber elastic layer forms the main body of the polyurethane wear-resistant layer. The polyurethane anchor posts and the main body of the polyurethane wear-resistant layer are continuously molded, creating an embedded structure of the polyurethane wear-resistant layer around the sieve holes.

[0029] The interface transition layer is distributed between the inner wall of the inverted locking groove and the polyurethane anchor post, extending to the surface of the rubber elastic layer facing the polyurethane wear-resistant layer. The interface transition layer covers the bottom and walls of the inverted locking groove, as well as the upper surface of the rubber elastic layer, and is located between the polyurethane anchor post and the rubber elastic layer. The interface transition layer is not used as a separate load-bearing plate layer, but rather forms a continuous interface filling structure between the polyurethane wear-resistant layer and the rubber elastic layer.

[0030] The upper opening of the sieve hole is formed by a polyurethane wear-resistant layer to create a wear-resistant lip, which is continuously provided along the upper opening of the sieve hole. The upper edge of the wear-resistant lip is a rounded edge with a radius of 0.5mm to 3mm. This rounded edge is formed by the rounded corner forming surface at the corresponding position of the upper mold core pillar. After demolding, the burrs at the upper opening of the sieve hole are trimmed to ensure that the wear-resistant lip remains continuous and intact.

[0031] The lower opening of the sieve aperture is formed by a rubber elastic layer, creating a continuous rubber lower edge. A pressure-relieving groove, communicating with the lower opening of the sieve aperture, is located on the side of the rubber elastic layer facing away from the sieve aperture. This pressure-relieving groove is situated within the rubber elastic layer and is spaced apart from the polyurethane wear-resistant layer. "Communicating with the lower opening of the sieve aperture" means that the side of the groove closest to the sieve aperture is connected to the lower edge of the aperture. "The pressure-relieving groove does not penetrate the polyurethane wear-resistant layer" means that rubber material remains between the bottom of the groove and the polyurethane wear-resistant layer.

[0032] A rubber spacer layer, with a thickness of 0.5 mm to 5 mm, is provided between the bottom of the pressure relief groove and the polyurethane wear-resistant layer. This rubber spacer layer keeps the pressure relief groove within the rubber elastic layer, preventing it from cutting into the polyurethane wear-resistant layer. The pressure relief groove is positioned so as not to cut off the inverted locking grooves around the screen holes, nor to sever the continuous rubber bridge between adjacent inverted locking grooves.

[0033] In this embodiment, the polyurethane wear-resistant layer is located on the working surface, the rubber elastic layer is located on the back surface, and the periphery of the screen holes is connected by an inverted locking groove, polyurethane anchoring columns, and an interface transition layer. This structure differs from composite anti-clogging screens with an upper layer of low-hardness rubber and a lower layer of polyurethane, and also from composite screens that are only connected by adhesive, curtain fabric, or flat adhesive film.

[0034] Example 2: Structure of the annular locking zone around the sieve holes Based on Embodiment 1, the inverted locking groove is located within the annular locking area surrounding the sieve hole. The annular locking area surrounds the sieve hole, and the distance between the inner edge of the annular locking area and the wall of the sieve hole is 1.5 mm to 6 mm. This distance refers to the shortest distance from the wall of the sieve hole to the nearest edge of the area containing the inverted locking groove.

[0035] The lower limit of this distance is used to ensure that continuous rubber material is maintained between the screen hole wall and the undercut locking groove, preventing the undercut locking groove from getting too close to the screen hole wall and weakening the lower edge of the rubber. The upper limit of this distance is used to ensure that the undercut locking groove is still within the interlayer stress concentration area around the screen hole, preventing the undercut locking groove from failing to form an effective embedding constraint on the polyurethane wear-resistant layer around the screen hole after it moves away from the screen hole edge.

[0036] Each sieve hole has at least four inverted locking slots within its corresponding annular locking zone. The center-to-center distance between two adjacent inverted locking slots is 3mm to 12mm. For elongated sieve holes, the inverted locking slots are spaced apart along both sides of the sieve hole's length, with additional slots at the end of the sieve hole. For rectangular sieve holes, the inverted locking slots are spaced apart along the four edges of the hole. The center-to-center distance between two adjacent inverted locking slots is measured circumferentially along the sieve hole.

[0037] The center distance between two adjacent inverted locking grooves is set to 3mm to 12mm. The lower limit of this center distance is used to ensure that a continuous rubber bridge is formed between adjacent inverted locking grooves, preventing the rubber material around the screen holes from being cut by the groove structure. The upper limit of this center distance is used to ensure that there are dispersed polyurethane anchor posts around the screen holes, so that the polyurethane wear-resistant layer forms multiple embedded positions around the screen holes.

[0038] The inverted locking grooves are intermittently arranged along the circumference of the screen holes, forming a continuous rubber bridge between adjacent inverted locking grooves. The width of the continuous rubber bridge is 1mm to 5mm. A continuous rubber bridge refers to the continuous area of ​​rubber material retained between two adjacent inverted locking grooves. The continuous rubber bridge maintains the continuity of the rubber elastic layer around the screen holes, preventing the screen holes from being divided by the continuous groove structure.

[0039] The opening width of the inverted locking groove is 50% to 85% of the groove bottom width. When the opening width is less than 50% of the groove bottom width, the preforming and demolding of the rubber elastic layer becomes more difficult, and the resistance to the transition material and polyurethane casting material entering the groove bottom area increases. When the opening width is greater than 85% of the groove bottom width, the inverted locking groove approaches a straight groove structure, and the inverted shape with a wider inner side and a narrower outer side is insufficient. Therefore, the opening width is set to 50% to 85% of the groove bottom width.

[0040] The depth of the inverted locking groove is 10% to 35% of the thickness of the rubber elastic layer. When the groove depth is less than 10% of the rubber elastic layer thickness, the polyurethane anchor post does not penetrate deep enough into the rubber elastic layer; when the groove depth is greater than 35% of the rubber elastic layer thickness, the back support thickness of the rubber elastic layer is reduced. This range is used to achieve a balance between the embedment depth of the polyurethane anchor post and the remaining support thickness of the rubber elastic layer.

[0041] The undercut locking groove adopts a dovetail-shaped groove, T-shaped groove, or trapezoidal groove that is wider on the inside and narrower on the outside. The molding die is equipped with a core-pulling undercut boss corresponding to the undercut locking groove. After the rubber elastic layer is pre-formed, the undercut locking groove is formed by demolding through a core-pulling or split mold.

[0042] Example 3: Materials and Formation Methods of the Interface Transition Layer Based on Example 1, the interface transition layer is formed by curing a transition material. The transition material includes an isocyanate-terminated polyurethane prepolymer and activated rubber powder. By weight, the activated rubber powder is 5 to 25 parts relative to 100 parts of isocyanate-terminated polyurethane prepolymer. The particle size of the activated rubber powder is 80 to 200 mesh.

[0043] Isocyanate-terminated polyurethane prepolymers are used for compatibility with subsequent polyurethane castables. Activated rubber powder is used to introduce rubber phase components into the interfacial transition layer. Activated rubber powder is obtained by surface activation of vulcanized rubber powder made from natural rubber, butadiene rubber, or a blend of natural rubber and butadiene rubber. Surface activation is performed using plasma treatment, oxidation treatment, or silane coupling agent treatment. Activated rubber powder is dried before use to ensure that there is no visible free moisture on its surface.

[0044] When the amount of activated rubber powder added is less than 5 parts, the rubber phase content in the interfacial transition layer is low, making it difficult to form a transition structure compatible with the rubber elastic layer. When the amount of activated rubber powder added is more than 25 parts, the viscosity of the transition material increases, making it difficult to fully coat the inner wall and bottom of the inverted locking groove, and local voids easily appear when the polyurethane casting material enters the inverted locking groove. Therefore, the amount of activated rubber powder added is set to 5 to 25 parts.

[0045] When the particle size of activated rubber powder is coarser than 80 mesh, the uniformity of dispersion of the rubber powder in the thin-layer transition material decreases. When the particle size of activated rubber powder is finer than 200 mesh, the specific surface area of ​​the powder increases, the viscosity of the transition material increases, and the working window shortens. Therefore, the particle size of activated rubber powder is set to 80 to 200 mesh.

[0046] The preparation process of the transition material is as follows: Dried activated rubber powder is added to isocyanate-terminated polyurethane prepolymer and stirred to disperse the activated rubber powder within the isocyanate-terminated polyurethane prepolymer. After preparation, the transition material is coated or pressed into the inverted locking groove within the operable time. During coating, the transition material is first scraped into the inverted locking groove, and then leveled along the groove opening to cover the groove walls and bottom. For the side of the rubber elastic layer facing the polyurethane wear-resistant layer, a continuous thin layer is formed using a scraper or roller coating method.

[0047] The transition material should not fill the screen holes or block the pressure relief groove. If the transition material enters the screen holes or pressure relief groove, it should be removed before polyurethane pouring to ensure that the screen holes are unobstructed and that the pressure relief groove is connected to the bottom of the screen holes.

[0048] In this embodiment, the interface transition layer is disposed between the inner wall of the inverted locking groove and the polyurethane anchor post, and extends to the surface of the rubber elastic layer facing the polyurethane wear-resistant layer. This interface transition layer, together with the inverted locking groove and the polyurethane anchor post, forms a composite connection structure around the sieve holes, rather than simply serving as a planar adhesive layer between the polyurethane layer and the rubber layer.

[0049] Example 4: Wear-resistant lip, pressure relief groove and material parameters Based on Example 1, the wear-resistant lip is continuously provided along the upper opening of the sieve holes. The upper edge of the wear-resistant lip is a rounded edge with a radius of 0.5 mm to 3 mm. When the rounded radius is less than 0.5 mm, a sharp edge can still easily form at the upper opening of the sieve holes. When the rounded radius is greater than 3 mm, the effective opening size of the upper opening of the sieve holes is affected, and the particle size boundary is difficult to control. Therefore, the radius of the rounded edge is set to 0.5 mm to 3 mm.

[0050] The rubber lower edge is continuously set along the lower edge of the screen holes. The pressure relief groove is located on the side of the rubber lower edge facing away from the screen holes and communicates with the lower edge of the screen holes. The depth of the pressure relief groove is 15% to 40% of the thickness of the rubber elastic layer. When the groove depth is less than 15% of the rubber elastic layer thickness, the side of the rubber lower edge facing away from the screen holes lacks sufficient deformation space. When the groove depth is greater than 40% of the rubber elastic layer thickness, the continuous support area of ​​the rubber elastic layer around the lower edge of the screen holes is reduced. Therefore, the depth of the pressure relief groove is set to 15% to 40% of the rubber elastic layer thickness.

[0051] A rubber spacer layer, with a thickness of 0.5 mm to 5 mm, exists between the bottom of the pressure relief groove and the polyurethane wear-resistant layer. When the rubber spacer layer thickness is less than 0.5 mm, localized penetrations are easily formed during processing and use. When the rubber spacer layer thickness is greater than 5 mm, the contribution of the pressure relief groove to the localized deformation space at the lower edge of the rubber is reduced. Therefore, the thickness of the rubber spacer layer is set to 0.5 mm to 5 mm.

[0052] The polyurethane wear-resistant layer uses cast polyurethane elastomer with a Shore A hardness of 85 to 95. When the hardness of the polyurethane wear-resistant layer is lower than Shore A 85, the wear-resistant lip at the top of the screen opening is prone to rapid wear under the scouring of ore particles. When the hardness of the polyurethane wear-resistant layer is higher than Shore A 95, the flexibility of the polyurethane wear-resistant layer decreases, and the local stress of the screen increases under vibration load. Therefore, the Shore A hardness of the polyurethane wear-resistant layer is set to 85 to 95.

[0053] The rubber elastic layer uses a system of natural rubber, butadiene rubber, or a mixture of natural rubber and butadiene rubber, with a Shore A hardness of 55 to 75. If the hardness of the rubber elastic layer is lower than Shore A 55, the support stiffness on the back of the screen is insufficient. If the hardness of the rubber elastic layer is higher than Shore A 75, the local deformation capacity at the lower edge of the rubber decreases. Therefore, the Shore A hardness of the rubber elastic layer is set to 55 to 75.

[0054] The thickness of the polyurethane wear-resistant layer is 30% to 70% of the thickness of the rubber elastic layer. When the thickness of the polyurethane wear-resistant layer is less than 30% of the thickness of the rubber elastic layer, the wear-resistant thickness of the working surface is insufficient. When the thickness of the polyurethane wear-resistant layer is greater than 70% of the thickness of the rubber elastic layer, the proportion of the rubber elastic layer in the thickness direction of the screen decreases, and the rubber support thickness in the lower region of the screen opening is reduced. Therefore, the thickness of the polyurethane wear-resistant layer is set to 30% to 70% of the thickness of the rubber elastic layer.

[0055] In this embodiment, the Shore A hardness is tested according to the Shore A hardness test method. The test location is selected on a flat area of ​​the polyurethane wear-resistant layer and the rubber elastic layer, avoiding the edges of the screen holes, the inverted locking groove, and the pressure relief groove area. The thickness of the polyurethane wear-resistant layer and the thickness of the rubber elastic layer are measured along the thickness direction of the screen in the non-perforated area of ​​the screen.

[0056] Example 5: Preparation method of polyurethane and rubber composite mining screen This embodiment provides a method for preparing polyurethane and rubber composite mining screens, which are used to prepare the screens in Embodiments 1 to 4.

[0057] The first step is to prepare the rubber elastic layer. The rubber compound is placed into a molding die. The molding die includes a perforated core, a pressure-relieving groove forming section, and an undercut groove forming section. The perforated core forms the lower opening of the perforation and the edge of the lower opening of the rubber. The pressure-relieving groove forming section forms a pressure-relieving groove communicating with the lower opening of the perforation, and the undercut groove forming section forms an undercut locking groove located around the perforation. After being compressed in the mold, the rubber compound fills the areas surrounding the perforated core, the pressure-relieving groove forming section, and the undercut groove forming section, forming a rubber elastic layer with the lower opening of the perforation, the edge of the lower opening of the rubber, the pressure-relieving groove, and the undercut locking groove.

[0058] The second step is to pre-vulcanize the rubber elastic layer. The pre-vulcanization time is 50% to 75% of t90, where t90 is the positive vulcanization time of the rubber compound measured at the pre-vulcanization temperature. t90 is measured using a rubber vulcanizing apparatus and is based on the vulcanization curve of the rubber compound at the corresponding pre-vulcanization temperature.

[0059] Pre-curing time Determine using the following formula: ; In the formula, This indicates the pre-curing time of the rubber elastic layer, in minutes. This represents the pre-vulcanization coefficient, with a value ranging from 0.50 to 0.75; This indicates the positive vulcanization time of the rubber compound measured at the vulcanization temperature, in minutes.

[0060] The pre-curing time is determined using the above formula to ensure the rubber elastic layer reaches a state where it can be demolded while maintaining the outline of the undercut locking groove, while preserving space for continued curing during the subsequent composite curing process. After pre-curing, the rubber elastic layer should simultaneously meet the following conditions: First, after the rubber elastic layer is removed from the molding mold, the lower opening of the sieve, the edge of the rubber lower opening, the pressure relief groove, and the undercut locking groove can maintain the molding outline; Second, the groove opening width and groove bottom width of the undercut locking groove can be retained according to the design dimensions, and the groove opening does not close; Third, the side of the rubber elastic layer facing the polyurethane wear-resistant layer can withstand subsequent grinding, cleaning, and plasma treatment.

[0061] When the pre-curing time is less than 50% of t90, the dimensional stability of the rubber elastic layer after demolding is insufficient. When the pre-curing time is more than 75% of t90, the space for the rubber elastic layer to continue curing during subsequent composite curing is reduced. Therefore, this application limits the pre-curing time to 50% to 75% of t90.

[0062] The third step is to perform surface treatment on the pre-vulcanized rubber elastic layer. The surface treatment targets include the side of the rubber elastic layer facing the polyurethane wear-resistant layer, the inner wall of the inverted locking groove, and the lower edge of the sieve opening. The surface treatment includes grinding, cleaning, and plasma treatment in sequence.

[0063] The surface roughness Ra after grinding is 6.3 μm to 25 μm. When Ra is below 6.3 μm, the mechanical adhesion area of ​​the rubber elastic layer surface to the transition material is insufficient. When Ra is above 25 μm, the surface of the rubber elastic layer is prone to excessively deep scratches, affecting the dimensional stability of the inverted locking groove opening and the lower edge of the sieve hole. Therefore, the surface roughness Ra after grinding is set to 6.3 μm to 25 μm.

[0064] Cleaning is performed using anhydrous ethanol or a rubber surface cleaner, ensuring complete evaporation of any residual solvent after cleaning. The plasma treatment power is 100W to 300W, and the treatment time is 30s to 180s. If the power is below 100W or the treatment time is below 30s, the activation level of the inner wall of the inverted locking groove and the upper surface of the rubber elastic layer is insufficient. If the power is above 300W or the treatment time is above 180s, the rubber surface is prone to excessive aging or localized embrittlement. Therefore, the plasma treatment power is set to 100W to 300W, and the treatment time is set to 30s to 180s. The plasma nozzle or treatment electrode should cover the inner wall of the inverted locking groove, the bottom of the groove, and the lower edge of the sieve opening; it should not only treat the planar area of ​​the rubber elastic layer.

[0065] The fourth step is to form an interface transition layer. The transition material is applied to the inner wall of the inverted locking groove and the surface of the rubber elastic layer facing the polyurethane wear-resistant layer. For the inverted locking groove, the transition material is first scraped into the groove, then leveled along the groove opening with a scraper to cover the groove walls and bottom. For the side of the rubber elastic layer facing the polyurethane wear-resistant layer, a continuous thin layer is formed using a scraper or roller coating method. The transition material should not clog the bottom of the screen opening or fill the pressure relief groove. If the transition material enters the pressure relief groove, it should be removed before polyurethane pouring.

[0066] Step 5: Casting the polyurethane castable. Before casting, the polyurethane castable is vacuum degassed. The gauge pressure during vacuum degassed is -0.08 MPa to -0.10 MPa, and the degassed time is 5 min to 15 min. This range is used to remove air bubbles introduced during the mixing process of the polyurethane castable and to avoid an increase in the viscosity of the polyurethane castable due to excessive degassed time.

[0067] After degassing, the polyurethane casting material is poured into a mold containing a rubber elastic layer. The polyurethane casting material covers the side of the rubber elastic layer facing the polyurethane wear-resistant layer and enters the inverted locking groove to form a polyurethane anchor post. Simultaneously, a wear-resistant lip is formed at the upper opening of the screen hole forming part in the upper mold. During casting, the area of ​​the inverted locking groove is first wetted by the polyurethane casting material, and then the upper mold cavity is filled.

[0068] Step 6: Insulate and cure the mold. After pouring, insulate and cure at 80℃ to 110℃ for 2 to 5 hours to allow the polyurethane wear-resistant layer, interface transition layer, and rubber elastic layer to be compositely formed. The insulation and curing temperature and time are determined according to the curing reaction window of the cast polyurethane elastomer, and are used to ensure that the polyurethane wear-resistant layer and polyurethane anchor post complete the initial curing within the mold.

[0069] After demolding, the material is post-cured at 90℃ to 120℃ for 6 to 16 hours. Post-curing is used to further cure the polyurethane wear-resistant layer and to complete the remaining vulcanization of the rubber elastic layer in a composite state. After post-curing, the screen is trimmed, residual burrs inside the screen holes are cleaned, and it is checked whether the pressure relief groove is connected to the lower opening of the screen holes. If there is local residual polyurethane at the pressure relief groove, it should be removed, but the lower edge of the rubber should not be cut off.

[0070] Example 6: A specific specification In one specific specification, the total thickness of the screen body is 30mm, the thickness of the polyurethane wear-resistant layer is 12mm, and the thickness of the rubber elastic layer is 18mm. The Shore A hardness of the polyurethane wear-resistant layer is 90, and the Shore A hardness of the rubber elastic layer is 65. The screen holes are elongated strip-shaped, and the width of the screen holes is determined according to the target particle size to be screened.

[0071] An annular locking zone is provided around each sieve hole, with a 3mm distance between the inner edge of the annular locking zone and the sieve hole wall. Inverted locking grooves are intermittently arranged on both sides along the length of the sieve hole, and inverted locking grooves are also arranged at both ends of the sieve hole. A continuous rubber bridge is formed between two adjacent inverted locking grooves, with a width of 3mm. The groove opening width is 70% of the groove bottom width, and the groove depth is 20% of the rubber elastic layer thickness.

[0072] The wear-resistant lip at the top of the sieve opening is continuously set along the circumference of the sieve opening, and the radius of the rounded corner of the upper edge of the wear-resistant lip is 1.5mm. The bottom of the sieve opening is formed by a rubber elastic layer, and a pressure relief groove is set on the side of the rubber bottom edge away from the sieve opening and is connected to the bottom of the sieve opening. The depth of the pressure relief groove is 25% of the thickness of the rubber elastic layer, and a rubber spacer layer with a thickness of 2mm is retained between the bottom of the pressure relief groove and the polyurethane wear-resistant layer.

[0073] The transition material consists of isocyanate-terminated polyurethane prepolymer and activated rubber powder. By weight, 15 parts of activated rubber powder are present for every 100 parts of isocyanate-terminated polyurethane prepolymer, and the activated rubber powder has a particle size of 120 mesh. The pre-curing time of the rubber elastic layer is 60% of t90. After pre-curing, the rubber elastic layer is polished, cleaned, and plasma-treated before being coated with the transition material, and then the polyurethane castable is poured. The gauge pressure of the polyurethane castable during vacuum degassing is -0.09 MPa, and the degassing time is 10 min. After pouring, it is cured at 95℃ for 3 hours, and after demolding, it is post-cured at 100℃ for 10 hours.

[0074] The specific specifications described above are used to illustrate the implementation process of this application. In actual production, appropriate dimensions and process parameters are selected within the scope defined in the claims, based on the screen thickness, screening particle size, screen amplitude, material moisture content, and ore hardness.

[0075] Example 7: Structural Explanation Differentiating it from Existing Composite Screens The screen structure in this application is not a simple superposition of polyurethane and rubber layers. For disclosed polyurethane and rubber composite flexible anti-clogging screens, they typically employ an upper low-hardness rubber screen layer, a lower polyurethane layer, and a middle fabric skeleton, forming a composite structure through adhesive bonding and secondary vulcanization. The anti-clogging mechanism of this structure primarily relies on the deformation of the upper rubber screen surface and the inverted conical hole shape. This application places the polyurethane wear-resistant layer on the working surface, the rubber elastic layer on the back surface, and sets inverted locking grooves and polyurethane anchoring columns around the screen holes, transforming the interlayer connection at the screen hole edges from a planar composite to a spatially embedded composite.

[0076] For publicly disclosed high-elasticity anti-clogging polyurethane screen plates, they mainly rely on the expansion of the polyurethane elastic screen surface and the screen holes (smaller at the top and larger at the bottom) during vibration to reduce clogging. The anti-clogging structure of this application does not solely rely on the inverted conical shape of the screen holes. Instead, it features a rubber lower edge formed by a rubber elastic layer at the lower opening of the screen holes, and a pressure-relieving groove communicating with the lower opening of the screen holes on the side of the rubber lower edge facing away from the screen holes. The pressure-relieving groove is located within the rubber elastic layer and does not penetrate the polyurethane wear-resistant layer. Therefore, the upper opening of the screen holes is formed by a wear-resistant lip by the polyurethane wear-resistant layer, and the lower opening of the screen holes is provided with local deformation space by the rubber elastic layer.

[0077] For previously disclosed composite materials that use isocyanate primers or films to improve the adhesion between polyurethane and rubber, the interface transition layer in this application is not used as a standalone planar adhesive layer. Instead, it is positioned between the inner wall of the inverted locking groove and the polyurethane anchor post, extending to the surface of the rubber elastic layer facing the polyurethane wear-resistant layer. The interface transition layer, in conjunction with the inverted locking groove and the polyurethane anchor post, creates a combined structure of material transition and spatial embedding around the sieve openings.

[0078] Therefore, the difference in this application lies not in the separate use of polyurethane materials, rubber materials, inverted conical screen holes, or interface primers, but in the integration of the working face polyurethane wear-resistant layer, the back rubber elastic layer, the screen hole perimeter inverted locking groove, the polyurethane anchoring column, the interface transition layer, and the pressure relief groove into an integrated structure around the wear, blockage, and interlayer peeling locations at the edge of the mine screen hole.

[0079] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A polyurethane and rubber composite mining screen, characterized in that, The screen includes a screen body and screen holes disposed on the screen body, characterized in that the screen body includes a polyurethane wear-resistant layer, an interface transition layer and a rubber elastic layer disposed sequentially from the working surface to the back surface. The rubber elastic layer has an inverted locking groove on the side facing the polyurethane wear-resistant layer and around the screen holes. The width of the groove opening is smaller than the width of the groove bottom. The polyurethane wear-resistant layer has polyurethane anchor columns that extend into the inverted locking groove. The polyurethane anchor columns are integrally formed with the polyurethane wear-resistant layer and are filled in the inverted locking groove. The interface transition layer is distributed between the inner wall of the inverted locking groove and the polyurethane anchor post, and extends to the surface of the rubber elastic layer facing the polyurethane wear-resistant layer. The sieve holes penetrate the polyurethane wear-resistant layer, the interface transition layer, and the rubber elastic layer. The upper opening of the sieve holes is formed by the polyurethane wear-resistant layer to form a wear-resistant lip, and the lower opening of the sieve holes is formed by the rubber elastic layer to form a rubber lower opening edge. The rubber elastic layer has a pressure relief groove on the side of the rubber lower opening edge away from the sieve holes, which is connected to the lower opening of the sieve holes. The pressure relief groove is located inside the rubber elastic layer and is spaced apart from the polyurethane wear-resistant layer.

2. The polyurethane and rubber composite mining screen according to claim 1, characterized in that, The inverted locking groove is located in the annular locking area around the sieve hole, and the distance between the inner edge of the annular locking area and the wall of the sieve hole is 1.5mm to 6mm; four or more inverted locking grooves are provided in the annular locking area corresponding to each sieve hole, and the center distance between two adjacent inverted locking grooves is 3mm to 12mm.

3. The polyurethane and rubber composite mining screen according to claim 2, characterized in that, The inverted locking grooves are intermittently arranged along the circumference of the screen holes, and a continuous rubber bridge is formed between two adjacent inverted locking grooves. The width of the continuous rubber bridge is 1mm to 5mm. The width of the inverted locking groove is 50% to 85% of the bottom width, and the depth of the inverted locking groove is 10% to 35% of the thickness of the rubber elastic layer.

4. The polyurethane and rubber composite mining screen according to claim 3, characterized in that, The interface transition layer is formed by curing a transition material, which includes isocyanate-terminated polyurethane prepolymer and activated rubber powder. By weight, the activated rubber powder is 5 to 25 parts relative to 100 parts of isocyanate-terminated polyurethane prepolymer, and the particle size of the activated rubber powder is 80 to 200 mesh.

5. The polyurethane and rubber composite mining screen according to claim 4, characterized in that, The wear-resistant lip is continuously provided along the upper opening of the screen hole, and the upper edge of the wear-resistant lip is a rounded edge with a radius of 0.5mm to 3mm. The lower edge of the rubber is continuously arranged along the lower opening of the sieve hole. The depth of the pressure relief groove is 15% to 40% of the thickness of the rubber elastic layer. There is a rubber spacer between the bottom of the pressure relief groove and the polyurethane wear-resistant layer. The thickness of the rubber spacer is 0.5mm to 5mm.

6. The polyurethane and rubber composite mining screen according to claim 5, characterized in that, The Shore A hardness of the polyurethane wear-resistant layer is 85 to 95, the Shore A hardness of the rubber elastic layer is 55 to 75, and the thickness of the polyurethane wear-resistant layer is 30% to 70% of the thickness of the rubber elastic layer.

7. A method for preparing polyurethane and rubber composite mining screens, applicable to the polyurethane and rubber composite mining screens according to any one of claims 1-6, characterized in that, Includes the following steps: To prepare the rubber elastic layer, the rubber compound is placed into the molding mold, so that the rubber elastic layer forms the lower opening of the sieve hole, the edge of the rubber lower opening, the pressure relief groove, and the inverted locking groove located around the sieve hole. The rubber elastic layer is then pre-vulcanized. The pre-vulcanized rubber elastic layer is surface treated to form an activated surface on the side of the rubber elastic layer facing the polyurethane wear-resistant layer, the inner wall of the inverted locking groove, and the lower edge of the sieve hole. A transition material is applied to the inner wall of the inverted locking groove and the surface of the rubber elastic layer facing the polyurethane wear-resistant layer to form an interface transition layer. Polyurethane casting material is poured into the mold containing the rubber elastic layer, so that the polyurethane casting material covers the side of the rubber elastic layer facing the polyurethane wear-resistant layer and enters the inverted locking groove to form a polyurethane anchor column, while a wear-resistant lip is formed at the top of the screen hole. The mold is heat-insulated and cured to form a composite polyurethane wear-resistant layer, interface transition layer and rubber elastic layer. After demolding, a polyurethane and rubber composite mining screen is obtained.

8. The method for preparing polyurethane and rubber composite mining screens according to claim 7, characterized in that, When preparing the rubber elastic layer, the rubber compound is pre-vulcanized in the molding die. The pre-vulcanization time is 50% to 75% of t90, where t90 is the positive vulcanization time of the rubber compound measured at the pre-vulcanization temperature. The pre-vulcanized rubber elastic layer retains the molding outline of the sieve opening, the rubber opening edge, the pressure relief groove, and the inverted locking groove.

9. The method for preparing polyurethane and rubber composite mining screens according to claim 8, characterized in that, When performing surface treatment on the pre-vulcanized rubber elastic layer, the side of the rubber elastic layer facing the polyurethane wear-resistant layer, the inner wall of the inverted locking groove, and the lower edge of the sieve hole are successively polished, cleaned, and plasma treated. The surface roughness Ra after polishing is 6.3 μm to 25 μm, the plasma treatment power is 100 W to 300 W, and the treatment time is 30 s to 180 s.

10. The method for preparing polyurethane and rubber composite mining screens according to claim 9, characterized in that, Before casting the polyurethane castable, the polyurethane castable is vacuum degassed. The gauge pressure during vacuum degassed is -0.08MPa to -0.10MPa, and the degassed time is 5min to 15min. After pouring, keep it at 80℃ to 110℃ for 2 to 5 hours to cure. After demolding, allow it to mature at 90℃ to 120℃ for 6 to 16 hours.

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