A tool path for friction stir welding

Abstract

The invention relates to a tool path for friction stir welding, a joining method in machine technology. In particular, the invention relates to a tool path for joining polymer materials.

Description

[0001] A TOOL PATH FOR FRICTION STIR WELDING

[0002] Technical Field

[0003] The invention relates to a tool path for friction stir welding, a joining method in machine technology.

[0004] In particular, the invention relates to a tool path for joining polymer materials.

[0005] State of the Art

[0006] Friction stir welding is a solid-state joining process in which the temperature remains lower than the material's melting point. This friction stir welding technique is commonly used on materials that are difficult to weld with fusion welding, such as aluminum alloys, titanium alloys, and polymers. Friction stir welding is an ecological welding method and since it produces no harmful radiation or toxic gases, uses less energy, and generates less waste than traditional fusion welding processes, it is environmentally friendly. This method eliminates melting-related defects such as distortion, cracking, and porosity. Friction stir welding typically joins parts in butt joint, lap joint, and T-joint shapes.

[0007] Typically, in the friction stir welding method, the parts are held in the butt, lap, or T-joint positions, and the tool is moved along a straight line as it rotates around itself, mixing the plates at a temperature close to the melting point due to the heat generated by the friction.

[0008] In prior art applications, the friction stir welding method typically involves bringing two materials into contact, moving the tool along a straight line where these materials will be combined, and performing the joining process while rotating at a certain speed. This straight tool path is the most basic and widely used. The welding tool moves in a straight line to create the weld joint. Linear tool paths are ideal for straight welds or those with simple curves. There have been no studies regarding the tool path in friction stir welding of polymer materials. In their patent application “TR 2016 / 04533”, Oksiiz and Karagbz described the method of friction stir welding, the parameters used in this process and the method of application in thermoplastics. The patent application numbered TR 2021 / 019464 and filed by Oksiiz and Karagbz with another company explains how it can perform two different friction stir welding techniques in one tool by changing an apparatus and an apparatus for a friction stir welding tool. Elyasi et al. used friction stir welding to join two PMMA plates into a T-joint. They used a standard milling machine with a friction stir welding tool attachment set to weld. During the process, the rotational speed and tool feed rate were kept variable while the tool plunge speed and tool rake angle of 0.2 mm and 2°, respectively, remained constant. At the end of the process, they measured the weld's tensile strength and hardness. They identified the optimal parameters for the highest strength and hardness values [1],

[0009] Adibeig et al. investigated friction stir welding of polymethyl methacrylate (PMMA) materials in buttock joints. They investigated the effects of process parameters on the tensile strength of butt joints using a tool made of SS-304 steel, which is resistant to erosion. They calculated the optimal feed rate, tool rotational speed, plunge depth, and plunge angle [2],

[0010] Derazkola et al. used friction stir welding to join PMMA sheets at the ends. They used a high- strength steel tool with a truncated pin profile to determine the best parameters [3],

[0011] Hajideh et al. also used this method to join PMMA and polycarbonate materials using a butt joint. Unlike previous studies, they used a heater to heat the materials and investigated how it affected the mechanical properties of the weld. They used Hl 3 hot work steel for the tool and AL-7075 aluminum for the shoulder, which has high thermal conductivity. They reported that the tensile strength at the level of 98% of the tensile strength of polycarbonate was achieved in the weld zone and hardness was higher when compared to polycarbonate [4],

[0012] Dashatan et al. investigated friction stir welding using overlapping PMMA and ABS sheets. They used a tool made of H13 steel. They drilled threads into the tool tip to improve its performance and increase frictional heat during rotation. They investigated the influence of process parameters on lap-shear strength. They reported that the plunge ratio was the most important factor influencing strength [5],

[0013] Looking at all of the studies presented above, it is clear that the tool moves in a straight line and provides joining. Prabhu et al. used a quadrangular-profiled tool path to join aluminum and copper sheets by friction stir welding and found that this method reduced weld zone defects [6],

[0014] The application numbered "CN115283865A" in the known state of the art relates to welding technology, specifically a wire welding apparatus and method. It is stated that when the weld substrate is a non-conductive polymer material, a DC power source is used to heat the discharge body to the softening temperature of the non-conductive polymer material and then heat the heated discharge body. It is claimed that the silk thread welding device developed in the device and method described in the document can effectively connect metals, ceramics, polymer-based glass, and other materials of the same and different types. As demonstrated in the documents above, when friction stir welding is used in the current system, some deficiencies are observed. One of these drawbacks is that the weld strength remains low, and welding can be done at slow speeds. Furthermore, because the polymer cannot reach the optimal temperature, a homogeneous joint is impossible to achieve, resulting in gaps. Another disadvantage is that heat generated by friction spreads more to one side. Furthermore, in the known state of the art, there is the issue of the joint being weak due to the joined section's thinness.

[0015] Another disadvantage of the system is that the two sides do not join well enough in the weld zone because the tool typically moves in a straight line in the forehead joints when using the friction stir welding technique. In such applications, the weld width remains proportional to the diameter of the tool in the stirring zone. As a result, gaps and roughness appear in the internal structure of the weld zone. Thus, the weld strength remains low.

[0016] As a result of the aforementioned drawbacks and the inadequacy of existing solutions regarding the subject matter, there is a need for a new tool path that can overcome the limitations of the art.

[0017] Brief Description and Objects of the Invention

[0018] The invention relates to a tool path for friction stir welding, a joining method in machine technology. In particular, the invention relates to a tool path for joining polymer materials.

[0019] The invention aims to join polymer materials using different tool paths. The tool path patterns include circular, zigzag, rectangular, trapezoidal, and helical. Because a circular, zigzag, rectangular, trapezoidal, or helical-shaped tool path is used instead of a straight path, there is no gap between the polymer plates during welding, resulting in increased strength. A better joint can be created.

[0020] Thanks to the invention a better transition between the two sides occurs in the weld zone, therefore a better joint occurs. A wider and more homogeneous joint results in better weld strength than its counterparts where the tool moves in a straight line. Similarly, due to the good penetration, the gaps in the joint area are reduced and a more robust internal structure is formed.

[0021] Description of The Figures

[0022] Figure-1: The figure showing a view of the tool path trajectories.

[0023] Figure-2: The figure showing a top view of the tool and polymer plates.

[0024] Figure-3: The figure showing the view of experimental application examples of tool paths. Figure-4: The figure showing the view of experimental application examples of tool paths.

[0025] Reference Numbers in the Figures

[0026] In order to better understand the tool path developed by the present invention, the parts and elements in the figures are numbered, and the equivalent of each number is given below.

[0027] 1. Tool path

[0028] 2. Polymer plate

[0029] 3. Tool

[0030] 4. Tool movement direction

[0031] A. Circular

[0032] B. Zigzag

[0033] C. Rectangle

[0034] D. Trapezoidal

[0035] E. Helical

[0036] Detailed Description of the Invention

[0037] The invention relates to a tool path (1) for friction stir welding, which is a joining method in machine technology. The invention relates to the use of friction stir welding with a tool (3) plunging into the polymer plates (2) have been connected to a welding table and brought closer together from the forehead, where the polymer plates (2) are brought into contact with each other manually or automatically and performing the rotational and advancing movements in the tool movement direction (4).

[0038] The tool path (1) patterns used by the tool (3) are circular (A), zigzag (B), rectangular (C), trapezoidal (D), and helical (E), as shown in Figure 1. The tool (3) rotates on the Z axis perpendicular to the polymer plates (2), providing solid-state welding in the tool direction movement (4) using circular (A), zigzag (B), rectangular (C), trapezoidal (D), and helical (E) shaped profiles in the YZ plane parallel to the plate.

[0039] The tool (3) rotates and advances along with the movement direction (4) shown in Figure 2. As a result of the friction created as a result of this movement, the polymer plates (2) are heated and welded by mixing with each other at a temperature close to the melting point.

[0040] The tool's (3) main motion parameters are tool speed, feed rate, and tool path (1). The tool speed is determined by the tool's (3) rotation per minute (on average 750-1500 rpm). As the tool speed rises, so does the heat amount, which is a fundamental component of the joining process. However, the heat must be generated at a temperature near or equal to the material's melting point. The feed rate refers to the distance per minute (on average 10-20 millimeters per minute) the tool (3) moves in biaxial motion. This is also important when combined with other parameters.

[0041] The tool path (1) refers to the route that the tool that performs the mixing and combining process will follow while moving. Within the scope of the invention, circular (A), zigzag (B), rectangular (C), trapezoidal (D), and helical (E) shaped tool paths (1) are used instead of the traditional straight line tool path (1), as shown in Figure 1. Thanks to these tool paths (1), when joining polymer plates (2) using the friction stir welding technique from the butt area, there will be no gap between the polymer plates (2), providing an advantage in joining capability.

[0042] In contrast to the existing system, the invention allows the tool (3) to follow a circular (A) orbital tool path (1) when joining with the friction stir welding tool. In this tool path (1), the welding tool (3) moves in a circular (A) pattern, forming the welding joint. The circular (A) tool path produces a stronger joint in polymer plates (2) than the linear path (Figure 3). Another option is to use a zigzag (B) tool path (1). The tool path (1) shows the movement of the welding tool from the welding axis to the right and left in a zigzag (B) pattern along the welding joint. This tool path (1) can be used to make wide welds or to join polymer plates (2) of various thicknesses.

[0043] Another method is to use a tool path (1) with a quadrangular or rectangular (C) trajectory to join polymer plates (2). This method improves weld strength by increasing weld seam thickness. Other methods include using trapezoidal (D) and helical (E) orbital tool paths (1). These methods can also result in a stronger weld joint.

[0044] It is demonstrated that the tool paths (1) developed with the present invention can be used to join polymer plates (2) with friction stir welding using a tool (3), such as circular (A), zigzag (B), rectangular (C), trapezoidal (D), and helical (E), as shown in Figure 1.

[0045] Monitoring the tool path (1) profiles developed with the invention revealed that the deficiencies in the state of the art for joining polymer plates (2) by friction stir welding had been reduced or partially eliminated. Those who use the friction stir welding technique to join polymer plates benefit from improved weld quality (2). REFERENCES

[0046] [1] Elyasi, M., & Derazkola, H. A. (2018). Experimental and thermomechanical study on FSW of PMMA polymer T-joint. The International Journal of Advanced Manufacturing Technology,

[0047] 97, 1445-1456. [2] Adibeig, M. R., Hassanifard, S., Vakili-Tahami, F., & Hattel, J. H. (2018). Experimental investigation of tensile strength of friction stir welded butt joints on PMMA. Materials Today Communications, 17, 238-245.

[0048] [3] H. Aghajani Derazkola & Abdolreza Simchi (2018) Experimental and thermomechanical analysis of friction stir welding of poly(methyl methacrylate) sheets, Science and Technology of Welding and Joining, 23:3, 209-218, DOI: 10.1080 / 13621718.2017.1364896

[0049] [4] Arif S, Alam T, Ansari AH, Shaikh MBN. Morphological characterization, statistical modelling and tribological behaviour of aluminum hybrid nanocomposites reinforced with micro-nano-silicon carbide. J Asian Ceram Soc. 2019; 7(4): 434-448.

[0050] [5] Dashatan, S. H., Azdast, T., Ahmadi, S. R., & Bagheri, A. (2013). Friction stir spot welding of dissimilar polymethyl methacrylate and acrylonitrile butadiene styrene sheets. Materials & design, 45, 135-141.

[0051] [6] Ambigai, R., & Prabhu, S. (2021). Analyzing the mechanical properties and characterization of aluminium (ADC-14) based functionally graded materials (FGM). Silicon, 1-12.

Claims

CLAIMS1. The friction stir welding method, characterized in comprising following steps;• Bringing two polymer plates (2) into proximity to each other manually or automatically, • Performing the rotation and feed movement of the tool (3) by following the tool movement direction (4); circular (A), zigzag (B), rectangular (C), trapezoidal (D) or helical (E) tool path (1),• Assembling of two polymer plates (2) by means of heat generated through the rotational and feed movement of the tool (3).

2. The friction stir welding method according to claim 1, wherein the tool’s (3) speed is within the range of 750 rpm and 1500 rpm.

3. The friction stir welding method according to claim 1, wherein the tool’s (3) feed rate is within the range of 10 millimeters / minute and 20 millimeters / minute.

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