A retractable friction welding device

Abstract

The utility model relates to the technical field of friction stir welding, especially to a back-pulling type friction welding device, comprising: a welding spindle comprising a shaft shoulder and a stirring needle arranged coaxially, a driving unit comprising a first driving member for driving the shaft shoulder and the stirring needle to rotate synchronously, and a second driving member for driving the stirring needle to displace axially relative to the shaft shoulder, the shaft shoulder and the stirring needle are brought into extrusion contact with two workpieces to be welded by a positioning member, the shaft shoulder and the stirring needle are rotated by a first driving assembly, the stirring needle contacts the connection of the two workpieces to be welded, the surfaces of the two workpieces to be welded are melted and adhered together by friction, the top and bottom of the connection of the two workpieces are contacted by the shaft shoulder and softened, and the softened parts of the top and bottom of the connection of the two workpieces are extruded to the welding position to fill and eliminate the keyhole when the welding is almost completed by a second driving assembly driving the stirring needle to retreat.

Description

Technical Field

[0001] This utility model relates to the field of friction stir welding technology, and in particular to a retraction friction welding device. Background Technology

[0002] Friction stir welding refers to a method in which a high-speed rotating stirring pin is inserted into the workpiece and moves along the welding direction. Frictional heat is generated at the contact point between the stirring pin and the workpiece, causing the surrounding metal to form a plastic softening layer. The softened metal fills the cavity formed behind the stirring pin under the action of the rotating stirring pin, and solid-state welding of the material is achieved under the extrusion action of the shoulder of the stirring pin.

[0003] Friction stir welding (FSW) relies on the friction between a high-speed rotating stirring pin and the workpiece to generate heat, thereby plasticizing the material and forming a dense weld. However, existing technologies have the following problems:

[0004] Keyhole defects: When the stirring pin withdraws from the workpiece at the end of welding, a keyhole is left behind. This must be filled using a lead-in plate or other complex processes, especially for circumferential welds. Keyhole defects can severely affect the structural integrity of the welded joint. The presence of a keyhole creates a weak point in the weld, reducing the strength and toughness of the welded joint. Under external forces, the keyhole is prone to becoming a stress concentration point, leading to the generation and propagation of cracks, ultimately affecting the reliability of the welded structure.

[0005] Therefore, a retraction friction welding device is proposed. Utility Model Content

[0006] In this section, as well as in the abstract and title of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this section, the abstract, and the title of this application. Such simplifications or omissions shall not be used to limit the scope of this utility model.

[0007] To address the shortcomings of existing technologies, one objective of this utility model is to provide a retraction-type friction welding device.

[0008] To achieve the above objectives, this utility model adopts the following technical solution: a retraction friction welding device, comprising:

[0009] A welding spindle, which includes a coaxially arranged shoulder and a stirring pin;

[0010] The drive unit includes a first drive member for synchronously rotating the shaft shoulder and the stirring pin, and a second drive member for axially displacing the stirring pin relative to the shaft shoulder; and,

[0011] The positioning unit includes a positioning element that drives the welding spindle to move toward the connection point of two workpieces to be welded and applies pressure through a first driving element and a second driving element.

[0012] As a preferred embodiment of the retraction friction welding device of this utility model, the first driving component includes a servo motor, a transmission cover shaft connected to the servo motor, a spline main shaft connected to one end of the transmission cover shaft near the shaft shoulder, and a spline center shaft connected inside the spline main shaft.

[0013] The shoulder and the stirring needle are both located at the same end of the spline center shaft.

[0014] As a preferred embodiment of the retraction friction welding device of this utility model, the second driving component includes a servo electric cylinder, the extended end of which is connected to a rotary retraction shaft, and the end of the rotary retraction shaft away from the servo electric cylinder extends into the interior of the transmission cover shaft and is connected to the spline center shaft through a first bearing.

[0015] The first driving component also includes a synchronous belt connected to the output end of the servo motor, one of the pulleys of the synchronous belt being connected to the output end of the servo motor, and the other pulley of the synchronous belt being fixedly sleeved on the transmission cover shaft;

[0016] The stirring needle is installed at the end of the spline central shaft away from the synchronous belt;

[0017] The shoulder is mounted on the splined spindle.

[0018] As a preferred embodiment of the retraction friction welding device of this utility model, the positioning component includes a linear motor, and the output end of the linear motor is connected to the reinforcing plate;

[0019] Both the first driving component and the second driving component are mounted on the reinforcing plate.

[0020] As a preferred embodiment of the retraction friction welding device of this utility model, it further includes a spindle housing sleeved on the spline spindle.

[0021] The spindle housing contains a fourth bearing and a fifth bearing, both of which are connected to the splined spindle.

[0022] Both the fourth and fifth bearings have clearances, with a clearance fit accuracy of level seven.

[0023] As a preferred embodiment of the retraction friction welding device of this utility model, the output end of the servo electric cylinder is connected to the rotary retraction shaft through a second bearing and a third bearing.

[0024] The second bearing is connected to the third bearing.

[0025] As a preferred embodiment of the retraction friction welding device of this utility model, it further includes a collaborative control unit, including a detection module connected to the first driving member, and a controller electrically connected to the first driving member and the second driving member respectively.

[0026] The detection module is used to detect the rotational speed information of the first driving component;

[0027] The controller is used to receive the rotation speed information of the first drive component and control the second drive component in real time to drive the stirring needle to retract.

[0028] In a preferred embodiment of the retraction friction welding device of this utility model, when the stirring pin retracts, the filling rate v at the weld joint is... f Contact area A s satisfy:

[0029]

[0030] Where L represents the flow coefficient of the material, v 0.4 Indicates the fill rate v f The inhibitory effect of A s =π, R s R is the shoulder radius. p The radius of the stirring needle.

[0031] In a preferred embodiment of the retraction friction welding device of this utility model, the rotational speed V1 of the shoulder causes the softening layer formed by the rotational extrusion friction at the contact point of the two workpieces to satisfy the following condition: the softening layer depth d soft ≥0.8 × aluminum alloy plate thickness, where 0.8 is the critical safety factor;

[0032] When the stirring needle retracts, the filling speed v for the welding area D f The ratio between the retraction speed v of the stirring needle and the speed v is: v f / v≥1.2;

[0033] When the shoulder is filled with the softened material of the heat-affected zone by the extrusion pressure F, the extrusion pressure P ≥ 12 MPa.

[0034] As a preferred embodiment of the retraction friction welding device of this utility model, during welding, the shoulder rotation affects the softening layer depth d formed on the workpiece to be welded. soft satisfy:

[0035]

[0036] Where α is the thermal diffusivity, β is the thermal action time, and β is the geometric factor.

[0037] The beneficial effects of this retraction friction welding device are as follows: A first driving component drives the stirring pin and the shoulder to rotate. A positioning component drives the rotating stirring pin to penetrate the contact area of ​​two workpieces to be welded. At the same time, the shoulder rotates and presses against the top and bottom of the contact area of ​​the two workpieces to be welded. When the stirring pin rotates, it contacts the connection point of the two workpieces to be welded. Through friction, the surfaces of the two workpieces to be welded melt and adhere together. When the shoulder rotates, it contacts the top and bottom of the connection point of the two workpieces, causing the top and bottom of the connection point of the two workpieces to soften. When the welding is almost completed, the second driving component drives the stirring pin to retract. The shoulder presses the softened parts of the top and bottom of the contact point of the two workpieces into the welding area to fill it, eliminating the keyhole. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram showing the shoulder and stirring pin of the present invention corresponding to the workpiece;

[0040] Figure 2 This is a schematic diagram of the overall process structure of this utility model;

[0041] Figure 3 This is a side view of the overall structure of the present invention.

[0042] Figure 4 This is a schematic diagram of the structure of the first driving component shown in this utility model;

[0043] Figure 5 This is a schematic diagram of the overall cross-sectional structure of the drive unit shown in this utility model;

[0044] Figure 6 This is a schematic diagram of the overall structure of the drive unit of this utility model;

[0045] Figure 7 This is a schematic diagram of the top structure of the drive unit of this utility model;

[0046] Figure 8 This is a top view of the drive unit of this utility model;

[0047] Figure 9 This is a right-side cross-sectional view of the drive unit of this utility model;

[0048] Figure 10 For the present utility model Figure 9A magnified structural diagram of position A in the diagram.

[0049] In the diagram: 100, welding spindle; 101, shoulder; 102, stirring needle; 102a, chuck; 102b, clamping nut;

[0050] 200. Drive unit; 201. First drive component; 201a. Servo motor; 201a-1. Motor flange bracket; 201a-2. Motor center adjustment plate; 201a-3. Reinforcing plate; 201a-4. Spindle housing; 201a-5. Housing cover plate; 201a-6. Fourth bearing; 201a-7. Fifth bearing; 201a-8. Pin; 201b. Synchronous belt; 201c. Transmission cover shaft; 201d. Splined spindle; 201e. Splined center shaft;

[0051] 202, Second drive component; 202a, Servo electric cylinder; 202a-1 Electric cylinder mounting bracket; 202a-2, Guide key; 202a-3, Second bearing; 202a-4, Third bearing; 202b, Rotary retraction shaft; 202c, First bearing; 202d, Bearing cover plate;

[0052] 300, Positioning unit; 301, Positioning component. Detailed Implementation

[0053] To make the objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0054] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0055] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0056] Example 1

[0057] Reference Figures 1-3This embodiment provides a retraction friction welding device, including: a welding spindle 100, which includes a shoulder 101 and a stirring needle 102 coaxially arranged; a drive unit 200, which includes a first drive member 201 for driving the shoulder 101 and the stirring needle 102 to rotate synchronously. The first drive member 201 only needs to be a device that can drive the stirring needle 102 to rotate, such as a motor, a turbine, or a gas cylinder; a second drive member 202 for driving the stirring needle 102 to move axially relative to the shoulder 101. The second drive member 202 only needs to be a device that can drive the stirring needle 102 to move linearly, such as a cylinder, a hydraulic cylinder, or an electric telescopic rod; and a positioning unit 300, which includes a positioning member 301 that drives the welding spindle 100 to move toward the connection of two workpieces S to be welded and applies pressure through the first drive member 201 and the second drive member 202.

[0058] The first driving component 201 drives the stirring needle 102 and the shoulder 101 to rotate. The positioning component 301 drives the rotating stirring needle 102 to drill into the contact area of ​​the two workpieces S to be welded. At the same time, the shoulder 101 rotates and presses against the top and bottom of the contact area of ​​the two workpieces S to be welded. When the stirring needle 102 rotates, it contacts the connection point of the two workpieces S to be welded. Through friction, the surfaces of the two workpieces S to be welded melt and adhere together. When the shoulder 101 rotates, it contacts the top and bottom of the connection point of the two workpieces S to soften the top and bottom of the connection point. When the welding is almost completed, the second driving component 202 drives the stirring needle 102 to retract. The shoulder 101 presses the softened parts of the top and bottom of the contact point of the two workpieces S to fill the weld area and eliminate the keyhole.

[0059] Example 2

[0060] Reference Figure 4 The first driving component 201 includes a servo motor 201a, on which a transmission cover shaft 201c is connected. The transmission cover shaft 201c is fixedly connected to the synchronous belt 201b. The transmission cover shaft 201c is bolted to a spline main shaft 201d. A spline central shaft 201e is connected to the spline main shaft 201d. The shaft shoulder 101 and the stirring needle 102 are both located at the same end of the spline central shaft 201e.

[0061] In this embodiment, the servo motor 201a is directly connected to the transmission cover shaft 201c, and the stirring needle 102 can be fixedly mounted on the shaft shoulder;

[0062] The servo motor 201a drives the transmission cover shaft 201c to rotate, the transmission cover shaft 201c drives the spline main shaft 201d to rotate, the spline main shaft 201d drives the shoulder 101 and the spline center shaft 201e to rotate, and the spline center shaft 201e drives the stirring needle 102 and the shoulder to rotate simultaneously, thus realizing the welding of materials.

[0063] The stirring needle 102 and the splined central shaft 201e are connected by a collet 102a and a clamping nut 102b. The collet 102a and clamping nut 102b are used to fix the stirring needle 102. The collet 102a and clamping nut 102b can be replaced with other structures that allow for quick replacement of the stirring needle 102. The shoulder 101 provides a clear axial position reference for the collet 102a. During assembly, when the collet 102a is close to the splined central shaft 201e, the shoulder 101 ensures that the collet 102a is installed in the correct position. In mechanical assembly, the height of the shoulder 101 is precisely designed to ensure that the relative position between the collet 102a and the splined central shaft 201e meets the design requirements. If the collet 102a is not positioned by the shoulder 101, the collet 102a may have an axial positional deviation, resulting in inaccurate connection between the stirring needle 102 and the splined central shaft 201e, affecting the normal operation of the entire device.

[0064] Example 3

[0065] Reference Figure 5 The second driving component 202 includes a servo cylinder 202a located on one side of the servo motor 201a. The extended end of the servo cylinder 202a is connected to a rotary retraction shaft 202b. The end of the rotary retraction shaft 202b away from the servo cylinder 202a extends into the interior of the transmission cover shaft 201c and is connected to the spline center shaft 201e through the first bearing 202c. The side of the first bearing 202c away from the spline center shaft 201e is connected to a bearing cover plate 202d. The first driving component 201 also includes a synchronous belt 201b connected to the output end of the servo motor 201a. One pulley of the synchronous belt 201b is connected to the output end of the servo motor 201a, and the other pulley of the synchronous belt 201b is fixedly sleeved on the transmission cover shaft 201c. The stirring needle 102 is installed at the end of the spline center shaft 201e away from the synchronous belt 201b, and the shoulder 101 is installed at the end of the spline main shaft 201d.

[0066] Among them, the bearing cover plate 202d can effectively block external dust, sand, metal shavings and other impurities from entering the bearing, thus preventing these impurities from entering the bearing, causing accelerated bearing wear and reducing the bearing's service life.

[0067] Unlike the embodiments described above, in this embodiment;

[0068] When the servo motor 201a is turned on, it drives the synchronous belt 201b to rotate. The synchronous belt 201b drives the transmission cover shaft 201c to rotate, which in turn drives the spline spindle 201d to rotate. The spline spindle 201d drives the shoulder 101 and the spline center shaft 201e to rotate, and the spline center shaft 201e drives the stirring needle 102 to rotate, thus achieving material welding. The shoulder 101 rubs against the workpiece S, creating a heat-affected zone. When welding is completed, the servo cylinder 202a is turned on, which drives the rotary retraction shaft 202b to move. The rotary retraction shaft 202b drives the spline center shaft 201e to move through the first bearing 202c. The spline center shaft 201e drives the stirring needle 102 to retract, and the shoulder 101 fills the softened material from the heat-affected zone into the weld, eliminating the keyhole.

[0069] Example 4

[0070] refer to Figure 5-10 The positioning component 301 includes a linear motor, the output end of which is connected to the reinforcing plate 201a-3. The first driving component 201 and the second driving component 202 are both disposed on the reinforcing plate 201a-3.

[0071] The positioning component 301 can also be a cylinder or other device that can directly drive the reinforcing plate 201a-3 to move. By opening the positioning component 301, the positioning component 301 drives the first driving component 201 and the second driving component 202 to move, so that the stirring needle 102 drills into the contact point of the two workpieces S to be welded, and at the same time, the shoulder 101 makes contact with the top and bottom of the contact point of the two workpieces S to be welded.

[0072] Reference Figures 2-7A motor flange bracket 201a-1 and a motor center adjustment plate 201a-2 are provided on one side of the servo motor 201a. The motor center adjustment plate 201a-2 is located on the side of the motor flange bracket 201a-1 closest to the servo motor 201a. The servo motor 201a is mounted on the motor center adjustment plate 201a-2, and the output end of the servo motor 201a passes through the motor center adjustment plate 201a-2 and the motor flange bracket 201a-1 in sequence and is connected to the synchronous belt 201b. The motor flange bracket 201a-1 is used to fix the servo motor 201a, ensuring that the servo motor 201a remains stable during operation and can be easily connected to mechanical methods. The flange bracket 201a-1 securely fixes the servo motor 201a to the mechanical device with bolts or nuts to prevent vibration or displacement of the servo motor 201a during operation. The motor center adjustment plate 201a-2 is mainly used to adjust the center position of the servo motor 201a to ensure the coaxiality and alignment of the servo motor 201a and the mechanical device. By adjusting the installation position of the servo motor 201a, the motor center adjustment plate 201a-2 ensures that the shaft of the servo motor 201a is aligned with the shaft of the mechanical device, thereby reducing vibration and improving transmission efficiency. The reinforcing plate 201a-3 is used to increase the strength of the motor flange bracket 201a-1 and the stability of the synchronous belt 201b installation.

[0073] Furthermore, a cylinder fixing bracket 202a-1 is provided on one side of the servo cylinder 202a. The cylinder fixing bracket 202a-1 is connected to the motor flange plate bracket 201a-1. The function of the cylinder fixing bracket 202a-1 is to firmly fix the servo cylinder 202a to the mechanical device, ensuring its stability during operation and helping to prevent displacement or damage caused by vibration or external force. The sides of the cylinder fixing bracket 202a-1 and the motor flange plate bracket 201a-1 away from the servo motor 201a are both connected to the spindle housing 201a-4 by bolts. The side of the spindle housing 201a-4 away from the cylinder fixing bracket 202a-1 is connected to an external... The cover plate 201a-5, spline spindle 201d, and spline center shaft 201e are all located inside the spindle housing 201a-4. The spindle housing 201a-4 can effectively prevent external dust, sand, metal shavings, and other impurities from entering the interior, thereby causing accelerated wear of the spline spindle 201d and spline center shaft 201e and reducing their service life. The electric cylinder fixing bracket 202a-1 is connected to the motor flange bracket 201a-1 by the guide key 202a-2. The servo motor 201a is connected to the spindle housing 201a-4 by the pin 201a-8. The guide key 202a-2 and the pin 201a-8 have the same function, both used for precise positioning and assembly.

[0074] Furthermore, the output end of the servo electric cylinder 202a is connected to the rotary retraction shaft 202b through the second bearing 202a-3 and the third bearing 202a-4. The second bearing 202a-3 and the third bearing 202a-4 are connected by bolts. The second bearing 202a-3 and the third bearing 202a-4 are equivalent to a separable coupling, which serves to connect the servo electric cylinder 202a and the rotary retraction shaft 202b.

[0075] Furthermore, the spindle housing 201a-4 houses a fourth bearing 201a-6 and a fifth bearing 201a-7, both of which are connected to the spline spindle 201d. These bearings allow the spline spindle 201d to automatically center itself during installation and enable it to withstand significant bidirectional axial pressure. Both bearings 201a-6 and 201a-7 have clearances. These clearances allow for some machining deviations in the workpiece S, facilitating assembly and compensating for some coaxiality errors, ensuring smooth operation. The clearance fit is grade seven, meaning the hole size is always larger than the shaft size, resulting in a certain clearance between them after assembly. This fit allows the shaft to rotate or slide freely within the hole. Grade seven accuracy corresponds to the ISO or IT grade seven tolerance in the Chinese national standard, indicating the allowable machining error range for the hole or shaft dimensions.

[0076] Example 5

[0077] Reference Figure 1-3It also includes a collaborative control unit, comprising a detection module connected to the first drive component 201, and a controller electrically connected to the first drive component 201 and the second drive component 202 respectively. The detection module is an encoder, which converts the rotational speed and axial position information of the first drive component 201 into pulse signals or digital signals in real time using incremental or absolute encoding. The controller is a PLC, whose input interface receives signals from the detection module via signal lines. The PLC's internal preset control program decodes and analyzes the signals from the detection module in real time, calculating the current welding progress and the parameters to be adjusted when the welding endpoint is approaching, based on the welding process requirements. The first drive component 201 can drive the stirrer... The stirring needle 102 rotates to weld the material. Based on feedback from the detection module, when the welding is nearing its end, the PLC sends a command to the first drive unit 201 to reduce its rotation speed and simultaneously sends a command to the second drive unit 202 to start retraction. After receiving the command, the first drive unit 201 adjusts its power supply frequency and voltage to ensure a smooth decrease in its rotation speed. After receiving the command, the second drive unit 202 drives the stirring needle 102 to retract at a preset speed. During the retraction process, the detection module continuously feeds back the rotation speed and axial position information to the PLC. The PLC monitors in real time and makes dynamic adjustments to ensure that the reduction in rotation speed and the retraction action are synchronized in time and position.

[0078] In summary, during operation, the device utilizes a servo motor 201a to drive a synchronous belt 201b, which in turn drives a transmission cover shaft 201c. The transmission cover shaft 201c then drives a splined central shaft 201e, which in turn drives a stirring needle 102 and a shoulder 101. The rotation of the stirring needle 102 facilitates material welding, while the rotation of the shoulder 101 brings it into contact with the material surface, creating a heat-affected zone that softens the material surrounding the weld. As the welding process nears completion, the speed of the servo motor 201a is reduced, and the system is simultaneously controlled... The controller controls the servo cylinder 202a to retract. The servo cylinder 202a drives the rotary retraction shaft 202b to retract via the second bearing 202a-3 and the third bearing 202a-4. The rotary retraction shaft 202b drives the stirring needle 102 to retract via the first bearing 202c, the spline center shaft 201e, and the chuck 102a, achieving precise synchronization between rotation and retraction. As the stirring needle 102 slowly retracts, the softened area fills the welding area, preventing the formation of keyholes and ensuring complete filling of the keyhole. After retraction is completed, the program controls the spindle to return to its original position, and the welding is completed.

[0079] Example 6

[0080] When the stirring pin 102 retracts, the filling rate v at the weld joint... f Contact area A s satisfy:

[0081]

[0082] Where L represents the flow coefficient of the material; when the material is an aluminum alloy, the value of L is 0.018. 0.4 This represents the retraction speed v raised to the power of 0.4, i.e., the exponent of v is 0.4. It is a nonlinear sensitivity factor obtained through fitting experimental data, representing the inhibitory effect on the filling rate. An increase in the retraction speed v → faster movement of the stirring pin 102 → shorter material heating time → reduced effective time for softening material to fill the keyhole. 0.4 The introduction of [a specific method / mechanism] quantifies the negative impact of this "time compression" on filling capacity, but the impact is weaker than a linear relationship (because the exponent < 1). A s =πR s 2 -R p 2 R s R is the radius of the shoulder 101. p The radius of the stirring needle is 102.

[0083] Engineering Phenomenon Verification:

[0084] When v doubles from 0.10 mm / s to 0.20 mm / s: if the relationship is linear, v 1 v f It should be reduced to 1 / 2;

[0085] Actual cause v 0.4 exist:

[0086]

[0087] That is, v f It only decreased to about 75.8% of the original value, not 50%, which is consistent with the experimental data (see Table 1):

[0088] Table 1

[0089]

[0090]

[0091] As shown in Table 1, when v increases by 100% (0.10 → 0.20), v f The reduction of only 34% (not 50%) indicates that FSW has a strong tolerance for speed increases, but compensatory measures are needed.

[0092] Furthermore, the workpiece S to be welded is an aluminum alloy plate;

[0093] During welding, the servo motor 201a drives the stirring pin 102 and the shoulder 101 to rotate at a speed of V1, and the servo electric cylinder 202a drives the stirring pin 102 to retract at a speed less than v.

[0094] Where V1 = 1200-1300 r / min, v < 0.2 mm / s.

[0095] During welding, the servo motor 201a drives the synchronous belt 201b to rotate, the synchronous belt 201b drives the transmission cover shaft 201c to rotate, and the transmission cover shaft 201c drives the stirring needle 102 and the shoulder 101 to rotate at a speed of 1200-1300 r / min through the spline center shaft 201e.

[0096] When the stirring needle 102 rotates, it contacts the joint of the two aluminum alloy plates. Through friction, the two aluminum alloy plates melt and stick together at the contact point with the stirring needle 102.

[0097] When the shoulder 101 rotates, it contacts the top and bottom of the connection between the two workpieces S, causing the top and bottom of the connection between the two aluminum alloy plates to soften.

[0098] Furthermore, during the welding process, the detection module converts the rotational speed and axial position information of the servo motor 201a into pulse signals or digital signals in real time through incremental or absolute encoding.

[0099] The controller's input interface receives signals from the detection module via signal lines. The controller's internal preset control program decodes and analyzes the signals from the detection module in real time, and calculates the current welding progress and the parameters that need to be adjusted when the welding endpoint is about to be reached, based on the welding process requirements.

[0100] When the welding is almost complete, the controller sends a command to the servo motor 201a to reduce the speed, and at the same time sends a command to the servo electric cylinder 202a to start the retraction.

[0101] The servo electric cylinder 202a drives the rotary retraction shaft 202b to retract via the second bearing 202a-3 and the third bearing 202a-4. The rotary retraction shaft 202b drives the stirring needle 102 to retract at a speed of less than 0.2 mm / s via the first bearing 202c, the spline center shaft 201e, and the chuck 102a. When the stirring needle 102 retracts, the softened top and bottom of the connection between the two workpieces S are squeezed to the weld by the shaft shoulder 101 to fill the gap and eliminate the keyhole.

[0102] The detection module continuously feeds back the rotation speed of the servo motor 201a to the controller. The controller monitors in real time and dynamically adjusts the retraction of the stirring needle 102 to ensure that the reduction in the rotation speed of the servo motor 201a and the retraction of the stirring needle 102 driven by the servo cylinder are synchronized in time and position.

[0103] The effect of the rotational speed V1 of the servo motor 201a on the welding performance is shown in Table 2:

[0104] Table 2 (Welding performance tests and destructive tests to verify optimal welding process parameters)

[0105]

[0106]

[0107] Among them, 6061 in Table 2 is a grade of aluminum alloy material, which belongs to the Al-Mg-Si alloy system;

[0108] As shown in Table 2, the welding performance of the servo motor 201a is better when the speed V1 is between 1200-1500 r / min, with the best welding performance at 1200-1300 r / min, where the tensile force reaches about 1.7-2.1T. (The data shows that too low a speed may lead to incomplete plasticization of the material, affecting the welding performance, while too high a speed may cause the material to be over-plasticized, also affecting the welding performance). Therefore, based on the data analysis, it is best to select a spindle speed range of 1200-1300 r / min to ensure that the material is well plasticized and reliable welding can be performed.

[0109] The retraction speed v of the stirring needle 102 is less than 0.2 mm / s, mainly to ensure sufficient time to fully fill the keyhole. The spindle speed has little effect on it (the prerequisite is that the basic speed must be met to ensure that the material can be fully plasticized). If the retraction speed is too fast, it will only lead to incomplete filling of the keyhole and result in holes. Therefore, the speed of retraction has a negligible effect on the material.

[0110] Furthermore, the rotational speed V1 of the shoulder 101 causes the softening layer formed by the rotational compression friction at the contact point of the two workpieces S to satisfy the following: the softening layer depth d soft ≥0.8 × aluminum alloy plate thickness, where 0.8 is the critical safety factor;

[0111] When the stirring pin 102 retracts, the filling speed v of the welding area D... f The ratio between the retraction speed v of the stirring needle 102 and the retraction speed v is: v f / v≥1.2;

[0112] When the shoulder 101 is filled with the softened material of the heat-affected zone by the extrusion pressure F, the extrusion pressure P ≥ 12 MPa.

[0113] During the welding process, when the above three conditions are met simultaneously, the welded workpiece has an S0 keyhole. The experimental data are shown in Table 3.

[0114] Table 3

[0115]

[0116]

[0117]

[0118] As can be seen from Table 3: the depth d of the softened layer soft ≥0.8× the thickness of the aluminum alloy plate, the filling speed v f The ratio v between the filling speed v and the retraction speed v of the stirring pin 102 f / v≥1.2 and the extrusion pressure P≥12 MPa. If any of these conditions is not met, defects will surely occur. For example:

[0119] v f <v: keyhole residue (such as A s =150 mm 2 , F = 2.0 kN, v = 0.15 mm / s → v f =0.10 mm / s)

[0120] P < 12 MPa: lack of fusion (such as A s =450 mm 2 , F = 4.0 kN → P = 8.9 MPa)

[0121] d soft Insufficient: incomplete penetration at the root (such as (A s =150 mm 2 , F = 2.0 kN → d soft =2.1 mm < 4.8 mm).

[0122] Furthermore, during welding, the depth d of the softened layer formed by the rotation of the shoulder 101 for the workpiece S to be welded soft Satisfies:

[0123]

[0124] Where, α is the thermal diffusivity, is the thermal action time, and β is the geometric factor;

[0125] Table 4

[0126]

[0127] Table 4 is the description of the main parameters for aluminum alloy materials.

[0128] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A retraction-type friction welding device, characterized in that: include: A welding spindle (100) includes a shoulder (101) and a stirring needle (102) arranged coaxially; The drive unit (200) includes a first drive member (201) for synchronously rotating the shoulder (101) and the stirring needle (102), and a second drive member (202) for axially displacing the stirring needle (102) relative to the shoulder (101); and, The positioning unit (300) includes a positioning element (301) that drives the welding spindle (100) to move toward the connection of two workpieces (S) to be welded and applies pressure by a first driving element (201) and a second driving element (202).

2. The retraction friction welding device as described in claim 1, characterized in that: The first driving component (201) includes a servo motor (201a), a transmission cover shaft (201c) connected to the servo motor (201a), a spline spindle (201d) connected to one end of the transmission cover shaft (201c) near the shoulder (101), and a spline center shaft (201e) connected inside the spline spindle (201d). The shoulder (101) and the stirring needle (102) are both located at the same end of the spline center shaft (201e).

3. The retraction friction welding device as described in claim 2, characterized in that: The second drive unit (202) includes a servo electric cylinder (202a), the extended end of which is connected to a rotary retraction shaft (202b), the end of which extends away from the servo electric cylinder (202a) into the interior of the transmission cover shaft (201c) and is connected to the spline center shaft (201e) through a first bearing (202c); The first driving component (201) further includes a synchronous belt (201b) connected to the output end of the servo motor (201a). One pulley of the synchronous belt (201b) is connected to the output end of the servo motor (201a), and the other pulley of the synchronous belt (201b) is fixedly sleeved on the transmission cover shaft (201c). The stirring needle (102) is installed at the end of the spline central shaft (201e) away from the synchronous belt (201b); The shoulder (101) is mounted on the spline spindle (201d).

4. The retraction friction welding device as described in claim 3, characterized in that: The positioning component (301) includes a linear motor, the output end of which is connected to the reinforcing plate (201a-3); The first driving member (201) and the second driving member (202) are both disposed on the reinforcing plate (201a-3).

5. The retraction friction welding device as described in claim 3 or 4, characterized in that: It also includes a spindle housing (201a-4) fitted onto the spline spindle (201d); The spindle housing (201a-4) is equipped with a fourth bearing (201a-6) and a fifth bearing (201a-7), both of which are connected to the spline spindle (201d). There are gaps in both the fourth bearing (201a-6) and the fifth bearing (201a-7), with a gap fit accuracy of level seven.

6. The retraction friction welding device as described in claim 5, characterized in that: The output end of the servo electric cylinder (202a) is connected to the rotary retraction shaft (202b) through the second bearing (202a-3) and the third bearing (202a-4); The second bearing (202a-3) is connected to the third bearing (202a-4).

7. The retraction friction welding apparatus as described in any one of claims 1, 2, 3, 4, and 6, characterized in that: It also includes a collaborative control unit, including a detection module connected to the first drive unit (201), and a controller electrically connected to the first drive unit (201) and the second drive unit (202) respectively; The detection module is used to detect the rotational speed information of the first driving component (201); The controller is used to receive the rotation speed information of the first drive unit (201) and control the second drive unit (202) to drive the stirring needle (102) to retract in real time.

8. The retraction friction welding device as described in claim 7, characterized in that: When the stirring needle (102) retracts, the filling rate v at the weld joint... f Contact area A s satisfy: Where L represents the flow coefficient of the material, v 0.4 Indicates the fill rate v f The inhibitory effect of A s =π(R) s 2 -R p 2 ), R s R is the radius of the shoulder (101). p The radius of the stirring needle (102) is given.

9. In the retraction friction welding device as described in claim 8, the rotational speed V1 of the shoulder (101) applies rotational extrusion friction to the contact area of ​​the two workpieces (S) to form a softened layer that satisfies the following condition: the softened layer depth d soft ≥0.8 × aluminum alloy plate thickness, where 0.8 is the critical safety factor; When the stirring needle (102) retracts, the filling speed v for the welding area D is... f The ratio between the retraction speed v of the stirring needle (102) and the retraction speed v is: v f / v≥1.2; When the shoulder (101) is filled with the softened material of the softened layer by the extrusion pressure of F, the extrusion pressure P ≥ 12 MPa.

10. The retraction friction welding apparatus as described in claim 9, wherein during welding, the rotation of the shoulder (101) results in a softening layer depth d formed on the workpiece (S) to be welded. soft satisfy: in, α is the thermal diffusivity. β is the thermal action time, and β is the geometric factor.

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