Welding method and device for ultra-high molecular weight polyethylene

Abstract

The invention relates to the technical field of polymer processing, in particular to a welding method and device for ultra-high molecular weight polyethylene. Specifically, the invention relates to a welding device which comprises a light transmitting device and a laser welding machine. The welding device can be used for welding ultra-high molecular weight polyethylene materials. The invention further relates to a welding method of the ultra-high molecular weight polyethylene material.

Description

Technical Field

[0001] The present invention relates to the field of polymer processing technology, in particular to the field of ultra-high molecular weight polyethylene processing technology, and in particular to a welding method and device for ultra-high molecular weight polyethylene materials. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMW-PE) refers to linear polyethylene with a viscosity-average molecular weight of at least 1.5 million. It is a thermoplastic engineering plastic with excellent overall performance. UHMW-PE exhibits excellent wear resistance, self-lubrication, impact resistance, corrosion resistance, and low-temperature resistance. Its extremely low surface energy and strong anti-fouling properties have led to its widespread application in chutes, buckets, specialty cables, bulletproof vests, artificial joints, and sports equipment.

[0003] Ultra-high molecular weight polyethylene (UHMWPE) materials often require splicing during use. The quality of the splicing process can have a significant impact on the material's mechanical properties (such as impact resistance, tensile strength, and breaking strength). If the splicing process is unreliable, UHMWPE products are prone to partial or complete damage due to external forces, which may affect product performance, shorten product lifespan, and increase usage or maintenance costs. Therefore, how to ensure the quality of the splicing process of UHMWPE products to meet production and application requirements is a key issue that requires research.

[0004] During plastic processing and use, welding is often used to eliminate surface defects and maintain the overall performance of the product. Traditional plastic welding techniques include hot air welding, ultrasonic welding, friction welding, and laser welding. Hot air welding equipment is compact, and the temperature and air volume can be adjusted steplessly, making it suitable for a wide range of applications. However, for ultra-high molecular weight polyethylene (UHMWPE), a material with a high melting temperature and variable joint gaps, hot air welding is not suitable for UHMWPE due to the large heat exposure zone and large surface temperature differences within the heat exposure zone. This can damage the surrounding material during welding, leading to weld defects. Ultrasonic welding is often used for lap welding of plastic materials, but UHMWPE requires butt welding to achieve surface flatness requirements, making ultrasonic welding unsuitable for UHMWPE products. Friction welding is a simple process with high repeatability, but is generally only suitable for welding plastic workpieces with at least one round component that does not require angular alignment.

[0005] Laser welding is a relatively mature and widely used method for plastic welding in recent years. Essentially, it involves focusing a laser beam via optical fiber on a specific area of ​​the thermoplastic to be welded, melting the plastic in that area and bonding it to the other parts. The process then cools to achieve a bonded connection. Laser welding is characterized by minimal (or no) debris, zero pollution, high precision, and high efficiency. It has been widely used in the automotive, aerospace, and electronic component manufacturing industries.

[0006] CN 104999658 A discloses a seamless welding method for ultra-high molecular weight polyethylene sheets. Seamless welding is achieved by filling powder into the groove of ultra-high molecular weight polyethylene. However, this method requires a high temperature and high pressure environment (needs to be heated to 200-300°C and pressurized to 6-10 MPa for 60-120 minutes), is complex to operate, and does not improve production efficiency.

[0007] There is still a need in the art for new welding devices and welding methods to simply and efficiently achieve precise welding of ultra-high molecular weight polyethylene materials. Summary of the Invention

[0008] The present invention provides a novel ultra-high molecular weight polyethylene material laser welding device and method, which can simply and efficiently achieve precise welding of ultra-high molecular weight polyethylene materials, eliminate product defects caused by the presence of welds, and improve the overall performance of the product.

[0009] In one aspect, the present application provides a welding device comprising:

[0010] a: a light-transmitting device, comprising a transparent component configured to allow the laser beam to pass through;

[0011] b: Laser welding machine, including a laser welding head, optical fiber and control cabinet, the laser welding machine is a handheld laser welding machine or a robotic arm laser welding machine;

[0012] The light-transmitting device is configured to move with the movement of the laser welding machine (i.e., the light-transmitting device is displaced synchronously with the movement of the laser welding machine) or rotate (i.e., the light-transmitting device can move around an axis or center point at the laser welding head) or rotate (i.e., the light-transmitting device can not only move around a certain axis or center point, but also make irregular curved motion).

[0013] When the laser welding machine is a handheld laser welding machine, the laser welding head is held by an operator to perform single or repeated welding to complete the welding work.

[0014] When the laser welding machine is a robotic arm laser welding machine, the laser welding head is configured to be embedded in the robotic arm and perform a single or repeated movement according to a trajectory recorded or set by the system to complete the welding work.

[0015] In certain embodiments, the transparent component can be flat or convex, and its shape can be selected from a cylindrical, elliptical, spherical, hemispherical, rectangular, polygonal, or a combination of a semicircular and a rectangular. Transparent components of different shapes can be replaced depending on the shape of the gap at the docking location. The transparent component can be made of a material selected from a group consisting of ordinary flat glass, quartz glass, sapphire glass, ruby ​​glass, and alumina ceramic.

[0016] In certain embodiments, the transparent component is spherical quartz glass.

[0017] In some embodiments, the transparent component can be placed directly on the weldment and moved, rotated, or turned by an external force during welding. In some embodiments, the transparent component is configured to be detachably connected to the laser welding head, for example, by a snap or rotating clamping assembly or nut.

[0018] In certain embodiments, the light-transmitting device further comprises a fixing device connected to the laser welding head, and the fixing device is connected to the laser welding head by a snap or a rotating pressing assembly or a nut.

[0019] In certain embodiments, the transparent component is configured to be mounted on a laser welding head.

[0020] In certain embodiments, the laser welding head includes an air blowing port, a distance adjustment ring, an optical lens assembly, a safety start button, and an optical fiber fixing port for connecting to a control cabinet.

[0021] In certain embodiments, the laser beam energy density of the laser welding machine = (welding power x welding speed) / spot diameter, and the spot diameter can be adjusted by adjusting the focus position.

[0022] In certain embodiments, the welding power of the laser welder is 0W-300W (e.g., greater than 0W, 0W-50W, 50W-100W, 100W-150W, 150W-200W, 200W-250W, or 250W-300W).

[0023] In some embodiments, the welding movement speed of the laser welding machine is 0m / s-1m / s (for example, greater than 0m / s, 0m / s-0.1m / s, 0.1m / s-0.2m / s, 0.2m / s-0.3m / s, 0.3m / s-0.4m / s, 0.4m / s-0.5m / s, 0.5m / s-0.6m / s, 0.6m / s-0.7m / s, 0.7m / s-0.8m / s, 0.8m / s-0.9m / s or 0.9m / s-1m / s).

[0024] In certain embodiments, the laser wavelength range of the laser welder is 1000nm–2000nm (e.g., 1000nm–1100nm, 1100nm–1200nm, 1200nm–1300nm, 1300nm–1400nm, 1400nm–1500nm, 1500nm–1600nm, 1600nm–1700nm, 1700nm–1800nm, 1800nm–1900nm, or 1900nm-2000nm).

[0025] In certain embodiments, the adjustable range of the laser spot diameter of the laser welding machine is 0.2 mm-4 mm (eg, 0.2 mm-0.5 mm, 0.5 mm-1 mm, 1 mm-2 mm, 2 mm-3 mm, or 3 mm-4 mm).

[0026] Figure 1 A laser welding device is shown as an example, including a control cabinet 1, an optical fiber 2, and a handheld laser welding head 3. In the figure, 3-1 represents a light-transmitting device, A is a partial enlarged view of 3-1, and B and C represent two alternative solutions for the light-transmitting device.

[0027] A: The transparent component is cylindrical and is connected to the laser welding head by snap fasteners.

[0028] B: The transparent component is spherical, embedded in a cavity and connected to the laser welding head by rotating and pressing;

[0029] C: The transparent component is hemispherical and is connected to the laser welding head by a nut.

[0030] The device of the present invention can be used for precise welding of ultra-high molecular weight polyethylene materials without applying high temperature and high pressure, thereby improving production efficiency.

[0031] In one aspect, the present application provides a method for welding ultra-high molecular weight polyethylene materials, comprising performing welding using the welding device of the present invention.

[0032] In certain embodiments, the method comprises the steps of:

[0033] (1) After closely butting the ultra-high molecular weight polyethylene materials to be welded, place them on an operating platform, or after closely butting the ultra-high molecular weight polyethylene materials to be welded, stick them to the substrate;

[0034] (2) placing a transparent component above the docking portion, or connecting the transparent component to the laser welding head, such as embedding it into the laser welding head;

[0035] (3) turning on the laser welding machine for operation, the operation comprising: first, focusing the laser beam through the transparent component on the butt joint, then moving the laser welding machine and irradiating the gap of the butt joint with the laser once or repeatedly, so that the ultra-high molecular weight polyethylene material in the irradiated area is melted and welded together;

[0036] During operation, the light transmitting device moves or rotates or turns along with the movement of the laser welder;

[0037] (4) Turn off the laser welding equipment, cool to room temperature, and the welding is completed.

[0038] In some embodiments, the method comprises welding using a welding rod. In some embodiments, step (1) comprises placing the welding rod into the butt joint.

[0039] In certain embodiments, step (1) includes pre-treating the butt joint, for example, processing the butt joint into a V-shaped or semicircular cross-section or other shape. Optionally, the treated butt joint can be welded with a welding rod to improve the overall welding quality.

[0040] In certain embodiments, step (2) is as follows: allowing a laser beam to pass through a transparent component and act on the welding rod and the weldment (i.e., the ultra-high molecular weight polyethylene material to be welded); after a single or repeated laser irradiation, the welding rod and the ultra-high molecular weight polyethylene body around the welding rod are simultaneously heated and melted; after cooling and solidification, the two pieces of ultra-high molecular weight polyethylene material are melted and welded together.

[0041] In certain embodiments, before step (3), the method further includes: setting system parameters and starting the operation after the device state stabilizes.

[0042] In certain embodiments, the operation process of the welding method of the present invention is as follows Figure 3 or Figure 4 shown.

[0043] The ultra-high molecular weight polyethylene material mentioned in the present invention can be an ultra-high molecular weight polyethylene sheet, sheet, film, ultra-high molecular weight polyethylene composite film material and other plastic products that include ultra-high molecular weight polyethylene. In certain embodiments, the ultra-high molecular weight polyethylene material is through melt extrusion molding, compression molding or sintering molding. In certain embodiments, the viscosity-average molecular weight of the ultra-high molecular weight polyethylene material is between 500,000 and 10,000,000 (for example, 500,000-1,000,000, 1,000,000-2,000,000, 2,000,000-3,000,000, 3,000,000-4,000,000, 4,000,000-5,000,000, 5,000,000-6,000,000, 6,000,000-7,000,000, 7,000,000-8,000,000, 8,000,000-9,000,000 or 9,000,000-10,000,000).

[0044] In some embodiments, the gap width at the docking portion is 0mm-10mm (e.g., greater than 0mm, 0mm-1mm, 1mm-2mm, 2mm-3mm, 3mm-4mm, 4mm-5mm, 5mm-6mm, 6mm-7mm, 7mm-8mm, 8mm-9mm or 9mm-10mm), and the depth does not exceed the thickness of the ultra-high molecular weight polyethylene material itself.

[0045] In certain embodiments, the welded ultra-high molecular weight polyethylene material is a plastic product containing ultra-high molecular weight polyethylene, and the gap depth does not exceed the thickness of the plastic product itself.

[0046] In certain embodiments, the composition of the welding rod used in the present invention includes one or more of ultra-high molecular weight polyethylene (UHMWPE), high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), and polyvinyl chloride (PVC); wherein the ultra-high molecular weight polyethylene is one of pure ultra-high molecular weight polyethylene or modified ultra-high molecular weight polyethylene; and the polypropylene is one of homopolymer polypropylene (PPH), block copolymer polypropylene (PPB), and random copolymer polypropylene (PPR).

[0047] In certain embodiments, the cross-sectional shape of the welding rod used in the present invention is one of circular, elliptical, triangular, rectangular, and sector-shaped.

[0048] In certain embodiments, the diameter of the welding rod is 0.1 mm-12 mm (0.1 mm-1 mm, 1 mm-2 mm, 2 mm-3 mm, 3 mm-4 mm, 4 mm-5 mm, 5 mm-6 mm, 6 mm-7 mm, 7 mm-8 mm, 8 mm-9 mm, 9 mm-10 mm, 10 mm-11 mm, or 11 mm-12 mm).

[0049] In certain embodiments, the color of the welding rod is one of colorless and transparent, white, blue, red, yellow, black, or the same color as the ultra-high molecular weight polyethylene material to be welded.

[0050] In this invention, if the gap at the joint is narrow, two pieces of ultra-high molecular weight polyethylene can be directly laser welded after being tightly butted together without inserting a welding rod in the gap. This method ensures the consistency of the overall material of the weldment, ensures uniform heating temperature across the heated surface, and offers advantages such as good surface gloss and essentially consistent mechanical properties.

[0051] Advantageous Effects of the Invention

[0052] This invention provides a novel laser welding device and method for ultra-high molecular weight polyethylene (UHMWPE). These devices enable precise welding of UHMWPE, eliminating defects caused by weld seams and improving overall product performance. The laser welding device and method do not require high temperature or high pressure, resulting in simplicity and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A laser welding device is shown as an example, including a control cabinet 1, an optical fiber 2, and a handheld laser welding head 3. In the figure, 3-1 represents a light-transmitting device, A is a partial enlarged view of 3-1, and B and C represent two alternative solutions for the light-transmitting device.

[0054] A: The transparent component is cylindrical and is connected to the laser welding head by snap fasteners.

[0055] B: The transparent component is spherical, embedded in a cavity and connected to the laser welding head by rotating and pressing.

[0056] C: The transparent component is hemispherical and is connected to the laser welding head by a nut.

[0057] Figure 2 1. A perspective view (A) and a cross-sectional view (B) of the V-groove in Example 1.

[0058] Figure 3 The welding operation flow of Example 1 is shown.

[0059] Figure 4 The welding operation flow of Example 2 is shown. DETAILED DESCRIPTION

[0060] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be obtained commercially.

[0061] Example 1

[0062] A welding device and method for ultra-high molecular weight polyethylene material is applied to the welding of two ultra-high molecular weight polyethylene composite films (viscosity-average molecular weight of 3 million). The specific steps are as follows:

[0063] Workpiece welding preparation: Tightly butt-join the two pieces of ultra-high molecular weight polyethylene composite film to be welded and place them on the operating platform. Use a tool to process the butt joint into a V-shaped cross-section. Place a white triangular welding rod (3mm diameter), mainly composed of high-density polyethylene, into the gap of the processed butt joint. Figure 2 A perspective view (A) and a cross-sectional view (B) of a V-groove are shown.

[0064] According to the shape of the gap at the joint, the transparent component selected in this embodiment is a spherical quartz glass component. The spherical quartz glass component is mounted on the laser welder, and the system parameters of the laser welder are adjusted. After the equipment state is stable, the welding operation is started.

[0065] The welding operation is performed. The operator sends welding instructions to the robotic laser welder via the control system. The laser welder irradiates the weld according to the weld trajectory recorded by the system, focusing the laser beam through the spherical quartz glass component onto the weldment and the welding rod. This operation is repeated over the weld area, melting the welding rod and the surrounding UHMWPE material simultaneously. Cooling and solidifying, the two pieces of UHMWPE are fused together. Finally, the robotic laser welder returns to its initial position along the guide rails, completing the laser welding of the two pieces of UHMWPE.

[0066] Figure 3 The operation flow of this embodiment is shown.

[0067] The mechanical properties of the welded ultra-high molecular weight polyethylene composite film were tested and evaluated, and the results are shown in Table 1.

[0068] Table 1

[0069] UHMWPE composite film Welding area Test standard Tensile strength MPa 17.7 12.4 ISO 37:2017 Surface gloss 11 11 ISO 2813:2014

[0070] Example 2

[0071] A device and method for welding ultra-high molecular weight polyethylene (UHMWPE) materials, comprising the same process steps as those described in Example 1, differs in that, in this embodiment, the gap at the butt joint is narrow. After closely butting the two UHMWPE materials together, laser welding is performed directly without inserting a welding rod into the gap. This method ensures uniform material quality throughout the weldment, ensuring uniform heating temperatures across the heated surface, and resulting in high surface gloss and substantially consistent mechanical properties.

[0072] Figure 4 The operation flow of this embodiment is shown.

[0073] Although the specific embodiments of the present invention have been described in detail, those skilled in the art will understand that various modifications and variations can be made to the details based on all the teachings disclosed, and these changes are within the scope of protection of the present invention. The full scope of the present invention is given by the appended claims and any equivalents thereof.

Claims

1. A welding device comprising: a: a light-transmitting device, comprising a transparent component configured to allow the laser beam to pass through; b: Laser welding machine, including a laser welding head, optical fiber and control cabinet, the laser welding machine is a handheld laser welding machine or a robotic arm laser welding machine; The light transmitting device is configured to move, rotate or turn along with the movement of the laser welding machine.

2. The welding device of claim 1, wherein the transparent component is planar or convex; Preferably, the shape of the transparent component is selected from one of cylindrical, elliptical, spherical, hemispherical, rectangular, polygonal, and semicircular + rectangular; Preferably, the material of the transparent component is selected from one of ordinary flat glass, quartz glass, sapphire glass, ruby ​​glass, and alumina ceramics.

3. The welding device according to claim 1 or 2, wherein the transparent component is configured to be placed above the welding position for use, or configured to be detachably connected to the laser welding head; Preferably, the light transmitting device further comprises a fixing device connected to the laser welding head, wherein the fixing device is connected to the laser welding head by a snap or a rotating pressing assembly or a nut; Preferably, the transparent heat dissipation component is configured to be embedded in a laser welding head.

4. The welding device according to any one of claims 1 to 3, wherein the laser welding head comprises an air blowing port, a distance adjustment ring, an optical lens assembly, a safety start button, and an optical fiber fixing port for connecting to a control cabinet; Preferably, the laser beam energy density of the laser welding machine = (welding power × welding speed) / spot diameter, and the spot diameter is adjusted by adjusting the focus position; Preferably, the welding movement speed of the laser welding machine is 0m / s-1m / s; Preferably, the laser wavelength range of the laser welding machine is 1000nm-2000nm; Preferably, the adjustable range of the laser spot diameter of the laser welding machine is 0.2 mm-4 mm.

5. The welding device according to any one of claims 1 to 4, which is used for welding ultra-high molecular weight polyethylene materials.

6. A method for welding ultra-high molecular weight polyethylene material, comprising welding using the welding device according to any one of claims 1 to 4; Preferably, the method comprises the following steps: (1) After closely butting the ultra-high molecular weight polyethylene materials to be welded, place them on an operating platform, or after closely butting the ultra-high molecular weight polyethylene materials to be welded, stick them to the substrate; (2) Place a transparent component above the joint, or connect the transparent component to the laser welding head; (3) turning on the laser welding machine for operation, the operation comprising: first, focusing the laser beam through the transparent component on the butt joint, then moving the laser welding machine and irradiating the gap of the butt joint with the laser once or repeatedly, so that the ultra-high molecular weight polyethylene material in the irradiated area is melted and welded together; During operation, the light transmitting device moves or rotates or turns along with the movement of the laser welder; (4) Turn off the laser welding equipment, cool to room temperature, and the welding is completed.

7. The method of claim 6, comprising welding using a welding rod; Preferably, the step (1) comprises placing a welding rod into the gap of the butt joint; Preferably, the step (1) includes pre-processing the docking portion, for example, processing the docking portion into a V-shaped, semicircular or other cross-sectional shape; Preferably, the step (1) comprises: Place the welding rod into the pre-treated joint for welding; Preferably, the width of the gap at the butt joint is 0 mm to 10 mm, and the depth does not exceed the thickness of the ultra-high molecular weight polyethylene material itself.

8. The method according to claim 6 or 7, wherein the ultra-high molecular weight polyethylene material is selected from ultra-high molecular weight polyethylene plates, sheets, films, and ultra-high molecular weight polyethylene composite film materials; Preferably, the ultra-high molecular weight polyethylene material is a plastic product containing ultra-high molecular weight polyethylene; Preferably, the ultra-high molecular weight polyethylene material is formed by melt extrusion, compression molding or sintering; Preferably, the viscosity-average molecular weight of the ultra-high molecular weight polyethylene material is between 50W and 1000W.

9. The method according to any one of claims 6 to 8, wherein the welding rod comprises one or more of ultra-high molecular weight polyethylene (UHMWPE), high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), and polyvinyl chloride (PVC); The ultra-high molecular weight polyethylene is one of pure ultra-high molecular weight polyethylene or modified ultra-high molecular weight polyethylene; the polypropylene is one of homopolymer polypropylene (PPH), block copolymer polypropylene (PPB) and random copolymer polypropylene (PPR); Preferably, the cross-sectional shape of the welding rod is one of circular, elliptical, triangular, rectangular, and fan-shaped; Preferably, the diameter of the welding rod is 0.1 mm-12 mm; Preferably, the color of the welding rod is one of colorless and transparent, white, blue, red, yellow, and black, or the same color as the ultra-high molecular weight polyethylene material to be welded.

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