A hand-held portable friction stir welding apparatus and method employing electromagnetic preheating

Abstract

The application belongs to the technical field of friction stir welding, and discloses a handheld portable friction stir welding equipment adopting electromagnetic preheating and a welding method. The friction stir welding equipment comprises a first shell, a motor fixedly arranged in the first shell, a second shell in a cylindrical structure with two open ends, one end of the second shell fixedly connected to the first shell and in communication with the inner cavity of the first shell, a stir head clamping shaft arranged in the second shell and coaxially arranged with the second shell, one end of the stir head clamping shaft connected to the output shaft of the motor, a stir head installed at the other end of the stir head clamping shaft, the stir head located outside the second shell, an electromagnetic coil fixedly arranged at the other end of the second shell and the electromagnetic coil hollowly sleeved on the stir head clamping shaft, and an electromagnetic coil controller fixedly arranged in the first shell and connected to the electromagnetic coil through wires.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of friction stir welding, and particularly relates to a handheld portable friction stir welding equipment adopting electromagnetic preheating and a welding method. BACKGROUND

[0002] Friction stir welding is a high-quality solid-phase welding method, and has the advantages of green environmental protection, high joint strength and small welding deformation compared with traditional melting welding. In recent years, friction stir welding has been widely applied to the fields of aerospace, rail transportation and shipbuilding. With the rapid development of manufacturing industry, there are more and more demands for friction stir welding in special environments such as space welding, on-orbit repair, underwater welding and weapon equipment repair.

[0003] However, the current friction stir welding equipment is mainly large equipment, and the large friction stir welding equipment is mostly installed in a fixed way in an indoor environment. When a workpiece needs to be friction stir welded, the workpiece only needs to be transported to the friction stir welding equipment for welding. The large friction stir welding equipment cannot be moved to the outdoor for on-site operation. At this time, a small friction stir welding equipment with small size, convenient to carry and capable of meeting outdoor welding is needed. However, the power output of the equipment will decrease when the equipment is reduced in size, which cannot meet the power requirement of welding and affects the welding effect. The portability and miniaturization of the equipment cannot be promoted, which is a technical problem to be solved. SUMMARY

[0004] The application aims to provide a handheld portable friction stir welding equipment adopting electromagnetic preheating, which can reduce the power requirement of friction stir welding, reduce the size of the welding equipment and improve the welding efficiency by heating the welding material through the electromagnetic coil.

[0005] The application also aims to provide a welding method of the handheld portable friction stir welding equipment adopting electromagnetic preheating, which can maintain the stability of the material heating temperature in the welding process and further ensure the welding quality.

[0006] The application provides the technical scheme as follows:

[0007] A handheld portable friction stir welding equipment adopting electromagnetic preheating comprises:

[0008] a first shell;

[0009] a motor fixedly arranged in the first shell;

[0010] a second shell in a cylindrical structure with both ends open; one end of the second shell is fixedly connected to the first shell and communicates with the inner cavity of the first shell;

[0011] a chucking shaft of the stirring head, which is arranged in the second housing and coaxially arranged with the second housing; one end of the chucking shaft of the stirring head is connected with the output shaft of the motor;

[0012] a stirring head, which is mounted on the other end of the chucking shaft of the stirring head, and the stirring head is located outside the second housing;

[0013] an electromagnetic coil, which is fixedly arranged at the other end of the second housing, and the electromagnetic coil is sleeved on the chucking shaft of the stirring head;

[0014] an electromagnetic coil controller, which is fixedly arranged in the first housing and connected with the electromagnetic coil through a wire.

[0015] Preferably, the output shaft of the motor is connected with the chucking shaft of the stirring head through a shaft coupling.

[0016] Preferably, the electromagnetic coil is a planar winding spiral coil and is coaxially arranged with the stirring head.

[0017] Preferably, a plurality of fixing blocks are fixedly arranged at the end of the second housing, and the fixing blocks are arranged along the circumference of the opening of the second housing.

[0018] Preferably, a plurality of arc-shaped grooves are arranged on the side of the fixing blocks facing the inner cavity of the second housing, and the electromagnetic coil is matched and clamped in the arc-shaped grooves.

[0019] Preferably, a plurality of heat dissipation holes are arranged on the first housing.

[0020] Preferably, the handheld portable friction stir welding device with electromagnetic preheating further comprises:

[0021] a temperature sensor, which is fixedly mounted on the second housing and arranged close to the electromagnetic coil.

[0022] Preferably, a handle is fixedly mounted on the first housing.

[0023] A welding method of a handheld portable friction stir welding device with electromagnetic preheating, using the handheld portable friction stir welding device with electromagnetic preheating, comprising:

[0024] placing the stirring head at the welding position and turning on the electromagnetic coil to preheat the welding material;

[0025] detecting the temperature of the electromagnetic coil in real time during the preheating process; when the detected temperature reaches the target temperature, starting the stirring head to weld;

[0026] In the welding process, the power output of the electromagnetic coil is controlled by the electromagnetic coil controller to ensure that the heating temperature remains stable during the welding process.

[0027] Preferably, in the welding process, the output power of the electromagnetic coil is controlled according to the following formula:

[0028]

[0029] where P base is the basic power, P unit is the unit power, T diff is the difference between the current temperature of the electromagnetic coil and the target temperature, T unit is the unit temperature, K p is the proportional gain coefficient, p i is the power percentage increase, p d is the power percentage decrease, H1(T diff ) and H2(T diff ) are step functions, H1(T diff ) takes the value of 1 when T diff is greater than 0, otherwise H1(T diff ) takes the value of 0, H2(T diff ) takes the value of 0 when T diff is greater than 0, otherwise H2(T diff ) takes the value of 1.

[0030] Preferably, the welding method of the handheld portable friction stir welding device using electromagnetic preheating further comprises: adjusting the parameters in the formula according to the current temperature T current of the electromagnetic coil;

[0031] wherein when 0℃≤T current <250℃, set K p =2.5, p i =25%, p d =5%;

[0032] when 250℃≤T current <500℃, set K p =1.2, p i =12%, p d =12%;

[0033] when T current ≥500℃, set K p =0.8, p i =8%, p d =25%.

[0034] The beneficial effects of the present application are:

[0035] The hand-held portable friction stir welding device with electromagnetic preheating provided by the application can realize the heating of the welding material before the formal start of the welding operation and during the welding process by arranging the electromagnetic coil at the position of the stirring head, so that the output power required by the welding device during the operation is greatly reduced, thereby reducing the size of the device and solving the technical problem of miniaturization of the device.

[0036] The hand-held portable friction stir welding device with electromagnetic preheating provided by the application can realize the heating of the welding material before the formal start of the welding operation and during the welding process by arranging the electromagnetic coil at the position of the stirring head, so that the output power required by the welding device during the operation is greatly reduced, thereby reducing the size of the device and solving the technical problem of miniaturization of the device.

[0037] The welding method of the hand-held portable friction stir welding device with electromagnetic preheating provided by the application can maintain the stability of the material heating temperature during the welding process, and further ensure the welding quality.

[0038] The welding method of the hand-held portable friction stir welding device with electromagnetic preheating provided by the application can maintain the stability of the material heating temperature during the welding process, and further ensure the welding quality. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The external structure diagram of the hand-held portable friction stir welding device with electromagnetic preheating provided by the application is shown.

[0040] Figure 2 The arrangement diagram of the heat dissipation hole provided by the application is shown.

[0041] Figure 3 The internal structure diagram of the hand-held portable friction stir welding device with electromagnetic preheating provided by the application is shown.

[0042] Figure 4 The structure diagram of the fixing block provided by the application is shown.

[0043] Figure 5 The control and feedback principle diagram of the temperature provided by the application is shown. DETAILED DESCRIPTION

[0044] The application will be further described in detail below with reference to the accompanying drawings, so that those skilled in the art can implement the application according to the description.

[0045] As Figures 1-4As shown, the present invention provides a handheld portable friction stir welding device with electromagnetic preheating, which mainly includes: a first outer shell 110, a second outer shell 120, a motor 130, a stirring head clamping shaft 140, a stirring head 150, an electromagnetic coil 160, and an electromagnetic coil controller 170.

[0046] The motor 130 is fixedly mounted inside the first housing 110. The second housing 120 is a cylindrical structure with openings at both ends; one end (opening) of the second housing 120 is fixedly connected to the first housing 110 and communicates with the inner cavity of the first housing 110. The stirring head clamping shaft 140 is disposed inside the second housing 120 and is coaxially arranged with the second housing 120. One end of the stirring head clamping shaft 140 is connected to the output shaft of the motor 130 via a coupling 141. The stirring head 150 is detachably mounted on the other end of the stirring head clamping shaft 140, and the stirring head 150 is located outside the second housing 120. The stirring head 150 can be driven to rotate by the motor 130 to realize the working process of friction stir welding.

[0047] The electromagnetic coil 160 is fixedly disposed at the other end (opening) of the second outer casing 120, and the electromagnetic coil 160 is loosely fitted onto the stirring head clamping shaft 140. The electromagnetic coil controller 170 is fixedly disposed inside the first outer casing 110. The electromagnetic coil controller 170 is connected to the electromagnetic coil 160 through a wire. The electromagnetic coil controller 170 can change the output power of the electromagnetic coil 160, thereby changing the heating temperature of the electromagnetic coil 160.

[0048] As a preferred embodiment, the electromagnetic coil 160 is configured as a planar wound spiral coil, and the electromagnetic coil 160 is coaxially arranged with the stirring head 150; this ensures that the electromagnetic coil 160 is closer to the welding material and maximizes the heating range of the electromagnetic coil 160.

[0049] A plurality of fixing blocks 121 are fixedly disposed at one end of the second outer casing 120 (the end where the electromagnetic coil 160 is disposed), and the fixing blocks 121 are spaced apart circumferentially along the opening of the second outer casing 120. Each fixing block 121 has a plurality of arc-shaped grooves 121a on the side facing the inner cavity of the second outer casing 120, and the helical portion of the electromagnetic coil 160 is matched and engaged in corresponding arc-shaped grooves 121a, thereby defining the position of the electromagnetic coil 160. The number of fixing blocks 121 is at least three.

[0050] As a preferred embodiment, the first housing 110 is provided with an array of heat dissipation holes 111 for dissipating heat from the motor 130 and ensuring the stable operation of the motor 130.

[0051] A handle 180 is fixedly installed at the lower end of the first housing 110 to facilitate welding operations by the user. A switch 112 is also provided at the lower end of the first housing 110 to turn the welding equipment on or off.

[0052] As a preferred embodiment, the friction stir welding equipment is further provided with a temperature sensor 161 for real-time detection of the temperature of the electromagnetic coil 160. The temperature sensor 161 is fixedly installed at one end of the second housing 120 where the electromagnetic coil 160 is located, and the temperature sensor 161 is positioned close to the electromagnetic coil 160.

[0053] As a preferred embodiment, a display screen 190 is also fixedly installed on the side of the first outer casing 110. The display screen 190 can display data such as the pressure of the stirring head 150, the rotation speed, and the current temperature of the electromagnetic coil 160.

[0054] This invention utilizes an electromagnetic coil positioned near the stirring head to generate eddy currents within the metal object through electromagnetic induction. The resistive heating effect of these eddy currents is then used to heat the welding material. Before welding begins, the electromagnetic coil preheats the welding material, rapidly raising it to the required temperature. Simultaneously, heating continues during welding via the electromagnetic coil, making the welding material more easily plasticized by the stirring head. This reduces the forging force and forward resistance required by the stirring head during welding, thereby reducing the power required for welding equipment operation, decreasing the motor load, and improving overall welding efficiency.

[0055] The present invention also provides a welding method using a handheld portable friction stir welding device with electromagnetic preheating. The specific process of using the aforementioned handheld portable friction stir welding device with electromagnetic preheating is as follows.

[0056] Place the stirring head in the welding (initial) position and turn on the electromagnetic coil to preheat the welding material. During preheating, the temperature of the electromagnetic coil is monitored in real time by a temperature sensor; when the target temperature is reached, the stirring head is activated to begin welding. During welding, the power output of the electromagnetic coil is controlled by an electromagnetic coil controller to ensure a stable heating temperature throughout the welding process.

[0057] (1) Electromagnetic coil preheating stage

[0058] An electromagnetic coil is fixed near the stirring head. When energized, it generates eddy currents, which heat the (metal) material through resistance. The design of the electromagnetic coil must consider the conductivity of the material and the size of the preheating zone. Handheld portable friction stir welding equipment utilizes electromagnetic induction to preheat the metal material, and welding is achieved through the mechanical force and rotation speed applied by the stirring head. The equipment's workflow is divided into a preheating stage and a welding stage, combined with temperature feedback control to ensure temperature stability during the welding process.

[0059] Through formula Q prc =P coil From t, we can know that the power P of the electromagnetic coil coil The heating rate is determined by the heat (W); the heating time (t) depends on the thermal conductivity of the material, the size of the preheating zone, and the required temperature change.

[0060] The heat required to heat a material, Q, can be calculated using the following formula. required = m·c·ΔT.

[0061] In the formula, m represents the mass of the material (kg), c represents the specific heat capacity of the material (J / (kg·K)), and ΔT represents the temperature rise of the material.

[0062] To ensure sufficient heat is provided during the preheating process, the following condition must be met: Q pre ≥Q required .

[0063] Among them, Q pre Q represents the heat generated during preheating. required This indicates the amount of heat generated when the material is heated.

[0064] (2) Welding stage

[0065] The stirring head and the electromagnetic coil work together to provide the heat required for the welding process, achieving a plasticizing effect. Simultaneously, because the electromagnetic coil's coverage area is larger than the working area of ​​the stirring head, it can radiate heat to the unwelded areas during the stirring head's operation, further preheating those areas.

[0066] The formula for the heat generated by the stirring head is: Q weld =F·v·η.

[0067] Where F represents the applied force (N), v represents the welding speed (m / s), and η represents the thermal efficiency, which is typically between 0.6 and 0.9.

[0068] (3) Temperature control and feedback mechanism

[0069] The handheld portable friction stir welding device is equipped with a main controller, which is electrically connected to an electromagnetic coil controller. The main controller monitors the current temperature and automatically adjusts the power output of the electromagnetic coil according to the set target temperature to ensure that the welding material remains within a suitable temperature range during the welding process. The temperature control and feedback principle is as follows: Figure 5 As shown.

[0070] As a preferred method, the output power of the electromagnetic coil is controlled during the welding process according to the following formula:

[0071]

[0072] Among them, P base Based on base power (W), P unit For unit power, P unit =1W,T diff T represents the difference (°C) between the current temperature and the target temperature. unit T is a unit of temperature. unit =1℃, K p p is the proportional gain coefficient. i To increase the power percentage, p d To reduce the power percentage, H1(T) diff ) and H2(T diff ) are step functions, when T diff When H1(T) is greater than 0 diff H1(T) takes the value 1, otherwise H1(T) diff The value is 0 when T diff When H2(T) is greater than 0 diff H2(T) takes the value 0, otherwise H2(T) diff The value is set to 1. The base power ensures a minimum power output to meet preheating requirements and can be set to the intermediate value of the electromagnetic coil output power or determined empirically. Power output is dynamically adjusted based on temperature difference to ensure rapid equipment response. Increased and decreased power are used to dynamically adjust the output power according to temperature changes to adapt to the temperature requirements during welding.

[0073] Since handheld portable friction stir welding equipment is generally only used for spot welding, the maximum required temperature is around 1000℃. Preferably, this invention employs different temperature adjustment strategies for different temperature stages to ensure heating efficiency and prevent overheating that could damage the welding material.

[0074] The specific method is as follows: based on the current temperature T current (°C) Adjust the parameters in the formula:

[0075] When the current temperature is detected to be in the low-temperature range, i.e. 0℃≤T current When the temperature is <250℃, set K p =2.5, p i =25%, p d =5%; quickly reaches the target temperature, improving heating efficiency.

[0076] When the current temperature is detected to be in the middle temperature range, i.e., 250℃≤T current When the temperature is <500℃, set K p =1.2, p i =12%, p d =12%; ensure stable heating temperature.

[0077] When the current temperature is detected to be in the high temperature range, i.e., T current When the temperature is ≥500℃, set K. p =0.8, p i =8%, p d =25%, to avoid overheating.

[0078] This invention sets different temperature adjustment strategies according to different temperature stages, mainly including two parts: sensitivity adjustment and response adjustment. Sensitivity adjustment is reflected in: K p The system can be adjusted based on its response characteristics to ensure that it can respond sensitively and robustly to differences between the target and actual temperatures. Response adjustment is achieved by adjusting P in a timely manner according to the actual temperature requirements during the welding process. i and P d To achieve a balance between rapid response and stable output.

[0079] The above adjustment methods can effectively achieve dynamic control of welding temperature, ensuring the stability and reliability of the welding process, thereby improving welding quality and the service life of welding equipment.

[0080] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A welding method using a handheld portable friction stir welding device with electromagnetic preheating, characterized in that, The handheld portable friction stir welding equipment using electromagnetic preheating includes: First outer shell; The motor is fixedly installed inside the first housing. The second outer shell is a cylindrical structure with openings at both ends; one end of the second outer shell is fixedly connected to the first outer shell and communicates with the inner cavity of the first outer shell; A stirring head clamping shaft is disposed inside the second housing and is coaxially arranged with the second housing; one end of the stirring head clamping shaft is connected to the output shaft of the motor. A stirring head is mounted at the other end of the stirring head clamping shaft, and the stirring head is located outside the second housing; An electromagnetic coil is fixedly mounted at the other end of the second housing, and the electromagnetic coil is loosely fitted on the stirring head clamping shaft; An electromagnetic coil controller is fixedly installed inside the first housing and connected to the electromagnetic coil via wires; The welding method includes: Place the stirring head at the welding position and turn on the electromagnetic coil to preheat the welding material; During the preheating process, the temperature of the electromagnetic coil is monitored in real time; when the temperature reaches the target temperature, the stirring head is activated to begin welding. During the welding process, the power output of the electromagnetic coil is controlled by an electromagnetic coil controller to ensure that the heating temperature remains stable during the welding process. During the welding process, the output power of the electromagnetic coil is controlled according to the following formula: ； in, Based on power, For unit power, This is the difference between the current temperature of the electromagnetic coil and the target temperature. Unit temperature This is the proportional gain coefficient. To increase the power percentage, To reduce the power percentage, and These are step functions, when When greater than 0 The value is 1, otherwise The value is 0, when When greater than 0 The value is 0, otherwise The value is 1; It also includes: based on the current temperature of the electromagnetic coil Adjust the parameters in the formula; Where, when 0°C ≤ When the temperature is <250°C, set =2.5, =25%, =5%; When 250°C ≤ When the temperature is <500°C, set =1.2, =12%, =12%; when When the temperature is ≥500°C, set =0.8, =8%, =25%.

2. The welding method of the handheld portable friction stir welding device using electromagnetic preheating as described in claim 1, characterized in that, The output shaft of the motor is connected to the clamping shaft of the stirring head via a coupling.

3. The welding method of the handheld portable friction stir welding device using electromagnetic preheating according to claim 2, characterized in that, The electromagnetic coil is a planar wound helical coil and is coaxially arranged with the stirring head.

4. The welding method of the handheld portable friction stir welding device using electromagnetic preheating according to claim 3, characterized in that, Multiple fixing blocks are fixedly provided at the end of the second outer shell, and the multiple fixing blocks are spaced apart circumferentially along the opening of the second outer shell; The fixing block has multiple arc-shaped grooves on the side facing the inner cavity of the second outer shell, and the electromagnetic coil is matched and engaged in the arc-shaped grooves.

5. The welding method of the handheld portable friction stir welding device using electromagnetic preheating as described in claim 1 or 4, characterized in that, The first outer casing has an array of heat dissipation holes.

6. The welding method of the handheld portable friction stir welding device using electromagnetic preheating according to claim 5, characterized in that, Also includes: A temperature sensor is fixedly mounted on the second housing and positioned close to the electromagnetic coil.

7. The welding method of the handheld portable friction stir welding device using electromagnetic preheating according to claim 1, characterized in that, A grip handle is fixedly mounted on the first outer shell.

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