TWI566872B - Laser welding apparatus and method thereof - Google Patents

Description

Laser welding equipment and method thereof

The present invention relates to a laser welding apparatus and method thereof, and more particularly to a laser welding apparatus and method thereof for controlling laser light energy.

Carbon steel screws have strong penetration force, but they are easy to rust. They are easy to produce rust spots on the building and affect the appearance. Stainless steel screws are too soft in physical properties. If they want to penetrate the iron plate, the penetration force is insufficient. The bi-metal screw uses carbon steel as a screw head and then stainless steel as a screw tail to achieve high penetration and rust resistance.

Friction welding is a common joining technique in this field, but it must be followed by a vehicle repair process to remove surface irregularities such as bulges or depressions caused by the welding process. The prior art uses laser welding. However, when the laser performs heterogeneous metal laser bonding, it can be found that a hole is generated at the end of the laser irradiation region, and the cause of the hole is mainly caused by the laser when the welding depth is deeper. The depth and width of the heat-affected zone will increase, and the metal that melts the surface will flow outward; when the laser stops, the metal will cool too quickly and cannot be reflowed to cause the hole to be generated.

Therefore, how to propose a laser welding equipment and its method to overcome the aforementioned problems is an extremely urgent issue in the industry.

In order to solve at least the above problems, the present invention provides a laser welding apparatus, comprising: a fixing unit for fixing two objects to be welded having a welding surface, the fixing unit and the two welding objects to each other with respective welding faces Engaging and synchronously rotating; the laser unit is configured to provide a laser beam to illuminate the joint of the welding surfaces of the two workpieces to be joined to each other for performing a welding process; and the blowing unit is used for the welding process The joint of the two objects to be welded provides a shielding gas; and a control unit is configured to control the energy of the laser light such that the energy of the laser light decreases in at least one order when the welding process is performed to the end.

Furthermore, in an embodiment, the control unit of the present invention may be a controller electrically connected to the laser unit to control the energy of the laser light provided by the laser unit. In another embodiment, the control unit of the present invention may include a controller and an optical lens set between the laser unit and the two objects to be soldered, to adjust the optical lens group to control the laser light by the controller. energy of.

The present invention further provides a laser welding method, comprising the steps of: providing two objects to be welded having a welding surface, respectively, so that the two objects to be welded are joined to each other to form a joint; and irradiating with a laser light a joint of the two to be welded to perform a welding process; during the welding process, a shielding gas is supplied to the joint, and the two objects to be welded are synchronously rotated for the laser to illuminate the joint; When the welding process is advanced to the end, the energy of the laser light is controlled to decrease in at least one order.

Furthermore, the step of providing a shielding gas to the joint includes: When the laser light illuminates the joint, the shielding gas is supplied to the joint; and when the laser light illuminates the joint one turn, the irradiation of the laser light is stopped first to stop providing the shielding gas. In addition, the laser welding method of the present invention further includes setting an initial energy and a final energy of the laser light to obtain an intermediate energy according to the initial energy and the final energy, and further setting the intermediate energy to The first order energy; further comprising setting an order to equally distribute the energy range of the intermediate value energy to the end energy according to the order to the first order to the last order.

The laser welding equipment and method of the present invention can eliminate the subsequent repair steps and greatly shorten the process time. In addition, the laser energy control can eliminate the holes generated at the end of the laser welding process, thereby improving the process quality.

11, 12‧‧‧Wears to be welded

111, 121‧‧‧ welding surface

13‧‧‧ joint

2‧‧‧Fixed unit

21‧‧‧Clamping device

22‧‧‧ Positioning device

221‧‧‧ welding window

3‧‧‧Laser unit

30‧‧‧Laser light

31‧‧‧Laser source

32‧‧‧welding head

4‧‧‧Blowing unit

5‧‧‧Control unit

51, 51’‧‧‧ controller

52‧‧‧Optical mirror

Steps S501 to S504‧‧

1 is a schematic structural view of an embodiment of a laser welding apparatus of the present invention; FIG. 2 is a schematic view of another embodiment of the laser welding apparatus of the present invention; and FIG. 3 is another embodiment of the laser welding apparatus of the present invention; FIG. 4A and FIG. 4B are explanatory diagrams of the laser light energy step decreasing of the laser welding apparatus of the present invention; and FIG. 5 is a schematic flow chart of the laser welding method of the present invention.

The embodiments of the present invention are described below by way of specific embodiments, and those skilled in the art can easily understand the present case from the contents disclosed herein. Other advantages and effects. It is to be understood that the structure, the proportions, the size and the like of the drawings are only used in conjunction with the disclosure of the specification for the understanding and reading of those skilled in the art, and are not intended to limit the practice of the present invention. The qualifications are not technically meaningful. Any modification of the structure, change of the proportional relationship or adjustment of the size should not be affected by the effects of the case and the objectives that can be achieved. The technical content can be covered.

Referring to Figures 1 and 2, the laser welding apparatus of the present invention comprises a fixing unit 2 for fixing two to-be-welded objects 11 and 12, a laser unit 3 for supplying a laser beam 30, and a blowing unit 4 for providing a shielding gas. And a control unit 5 that controls the energy of the laser light 30.

The two to-be-welded articles 11 and 12 respectively have a welding face 111 and 121, and the two welding faces 111 and 121 are in contact with each other at the joint 13. It should be noted that there are often problems with the holes in the welding of the pipe fittings or bars, and the influence of the flat welding is not large. The welding objects 11 and 12 in the present case may be heterogeneous metals, for example, stainless steel segments and carbon steel segments.

The fixing unit 2 includes two holding means 21 which, as shown in Figs. 1 and 2, respectively hold the two objects to be welded 11 and 12 and engage the welding faces 111 and 121 of the two objects to be welded 11 and 12 with each other. The two clamping devices 21 can be electrically connected to the driving device (not shown, for example, a stepping motor) to clamp the two welding objects 11 and 12 to rotate synchronously with the respective welding surfaces 111 and 121 engaged with each other. In addition, the fixing unit 2 further includes a positioning device 22, as shown in Fig. 3, the positioning device 22 is designed to have two ends (not labeled) for respectively inserting the two to-be-welded objects 11 and 12 into the two welding faces. 111 and The 121 members are joined to each other, and the positioning device 22 is also designed to have a welded window 221 to expose the joints 13 where the welding faces 111 and 121 are joined to each other, and the laser light 30 is irradiated to the joint 13 for welding. Thereby, the positioning device 22 can position the joint 13 of the two objects to be welded 11 and 12, and the image tracking instrument that tracks whether the laser light 30 illuminates the joint 13 can be omitted. In a specific implementation, the laser welding apparatus of the present invention can selectively use the clamping device 21 to cooperate with the image tracking instrument, or use the clamping device 21 to cooperate with the positioning device 22, so that the two objects to be welded 11 and 12 are joined to each other by the welding faces 111 and 121. And the joint 13 is rotated synchronously with respect to the positioning device 22.

The laser unit 3 includes a laser source 31 and a soldering head 32 that connects the laser source 31 with an optical fiber (not numbered), and provides laser light 30 to illuminate the joint 13 of the two solders 11 and 12 for the soldering process. During the soldering process, the fixing unit 2 rotates the two to-be-welded objects 11 and 12 one turn in synchronization, so that the laser light 30 emitted from the laser source 31 illuminates the joint 13 by the welding head 32. For example, the laser unit 3 can provide laser light 30 of less than 3000 watts (W), and the fixed unit 2 can rotate the two items to be welded 11 and 12 by about 1 mm/s or more.

The blowing unit 4 is configured to provide a shielding gas such as helium, neon or argon gas to the joint 13 of the two objects to be welded 11 and 12 during the welding process, thereby reducing the probability of metal oxidation. The oxide of the laser light 30 (i.e., the welded portion) is reduced, thereby improving the stability and strength when the two solders 11 and 12 are joined.

The control unit 5 is configured to control the energy of the laser light 30 such that the energy of the laser light 30 is delivered in at least one order during the welding process to the end Less. The control unit 5 includes a controller 51. As shown in Fig. 1, the controller 51 outputs an electrical signal to control the laser unit 3 to present corresponding laser light energy. In addition, as shown in FIG. 2, the control unit 5 may include a controller 51' and an optical lens group 52 disposed between the laser unit 3 and the two objects to be welded 11 and 12 to be controlled by the controller 51'. The optical lens group 52 is adjusted to control the energy of the laser light 30, for example, controlling the rotation angle of the attenuating piece (not shown) in the optical lens group 52 to attenuate the energy of the laser light 30, and the optical lens group 52 can also adjust the laser light 30. Direction and spot size.

Furthermore, the end of the so-called soldering process refers to the point where the laser irradiation is about to be closed, and the junction 13 of the two to-be-welded objects 11 and 12 for the laser light 30 is about to complete one turn or just one turn or more than one turn. That is, the laser light 30 illuminates the spot on the two objects to be welded 11 and 12 as soon as it intersects with the initial welding point of the welding process or just exceeds the initial welding point, and the laser light changes the position of the original energy. In addition, the energy of the laser light 30 is decremented by at least one step in the end of the welding process, as shown in FIG. 4A as a second order decrement, as shown in FIG. 4B as a fourth order decrement, and the time of each stage. Maintain 0.5μs or more. In addition, the control unit 5 is further configured to set an initial energy and a final energy of the laser light 30, to obtain an intermediate energy according to the initial energy and the final energy, and then set the intermediate energy to the first First order energy, and an energy range for setting a first order to average the energy of the intermediate value to the end energy according to the order is equally distributed to the first order to the last order. For example, the initial energy is set to 800W and the final energy is 400W. If the order is second order, the first energy is 600W and the second energy is 400W. If the order is not only second, the first order is 600W. The energy between the last 400W is equally distributed according to the order.

In a specific implementation, taking FIG. 1 as an example, the laser light 30 is provided by the laser source 31 to illuminate the joint 13 of the two objects to be welded 11 and 12 from the welding head 32, while the blowing unit 4 is supplemented with argon gas. At the same time as the laser light 30 is irradiated, the clamping device 21 rotates the two objects to be welded 11 and 12 coaxially, and stops the laser light 30 and then stops the air blowing after one rotation, wherein the thermal effect caused by the laser light 30 is used. The joint 13 of the two to-be-welded articles 11 and 12 is melted and then solidified by cooling, so that the joints 13 of the two to-be-welded articles 11 and 12 are metallurgically bonded to each other and welded together, wherein the welding process is carried out until the end of the welding process. The device 51 controls the energy of the laser light 30 to descend slowly in at least one step, and after the last-order energy is irradiated, the laser source 31 is turned off to eliminate the hole phenomenon.

Referring next to Fig. 5, a flow chart of the laser welding method of the present invention will be described. In step S501, the two soldering objects are joined to each other by the respective soldering surfaces to form a joint, and then proceed to step S502; in step S502, the joint of the two soldering materials is irradiated with a laser light to perform a soldering process, and then Proceed to step S503; in step S503, providing a shielding gas to the joint when the welding process is performed, and rotating the two objects to be welded to irradiate the joint of the two objects to be welded, and then proceeding to step S504; In step S504, when the welding process is performed until the last stage is completed, the energy of the laser light is decreased in at least one order. Moreover, the steps S503 to S504 include: providing a shielding gas at the joint when the laser light is irradiated to the joint; after the laser light is irradiated to the joint, stopping the irradiation of the laser light and stopping the supply of the shielding gas. In addition, steps S501 to S504 The method further includes: setting an initial energy and a final energy of the laser light to obtain an intermediate energy according to the initial energy and the final energy, and then setting the intermediate energy to the first energy; Setting an order to evenly distribute the energy range of the intermediate value energy to the last order energy according to the order to the first order to the last order, wherein the initial energy of the laser light is in the range of 400 watts to 750 watts. The rotation speed of the two to-be-welded materials is in the range of 2.6 mm/s to 10 mm/s, and the time of each step is maintained for 0.03 seconds or more.

The following is a comparison example (as shown in Table 1) and an experimental example (as shown in Table 2). The comparison example is a failure case. Holes are generated at the end of the welding process, as shown in the attached photo. However, the experimental case in this case was successful only after overcoming the failure case, and no hole was formed at the end of the welding process, as shown in the photo in the attached article. It should be noted that the table indicates that there is no step down with N.

In Comparative Example 1 of Table 1, the laser light energy is 350 W to 650 W, and The moving speed is 2 to 4.4 mm/s. After at least one turn, the laser light energy does not drop stepwise, so holes are formed at the end of the welding process. In Comparative Example 2, the laser light energy was 400 to 600 W, and the rotation speed was 2 mm/s. After at least one turn, the final stage gradually reduced the energy to 300 W, and the time of each step was maintained for 0.5 s or less, and holes were still generated. In Comparative Example 3, the laser light energy is 540 W, and the rotation speed is 4.4 mm/s. After at least one rotation, the energy is gradually reduced in the final stage. The first-order energy is 420 W, and the second-order energy is 300 W. The time of each step is maintained below 0.05 s. Holes are still created. In Comparative Example 4, the laser light energy is 600 W, the rotation speed is 5 mm/s, and after at least one rotation, the energy is gradually reduced in the final stage. The first-order energy is 500 W, the second-order energy is 400 W, and the time is maintained below 0.1 s. Create holes. In Comparative Example 5, the laser light energy is 450 W, and the rotation speed is 4.4 mm/s. After at least one rotation, the energy is gradually reduced in the final stage. The first order energy is 300 W, the second order energy is 250 W, and the third order energy is 200 W. The time is maintained below 0.2 s and holes are still produced. In Comparative Example 6, the laser light energy is 500 W to 750 W, and the rotation speed is 10 mm/s. After at least one rotation, the final stage reduces energy step by step, the first order energy is 400 W, the second order energy is 350 W, and the third order energy is 300 W. Each step is maintained for less than 0.1 s, and holes are still generated. In Comparative Example 7, the laser light energy is 400W to 750W, and the rotation speed is 4.4mm/s. After at least one rotation, the final stage reduces energy step by step. The first order energy is 350W, the second order energy is 330W, and the third order energy is 310W. The fourth-order energy is 280W, and the fifth-order energy is 250W. The time of each step is maintained below 0.1s, and holes are still generated.

In the experimental example 1 of Table 2, the laser light energy is 400 W to 600 W, and the rotation speed is 2.6 to 4.4 mm/s. After at least one rotation, the end section reduces the energy to 350W, maintaining time of 0.5s or more, can eliminate holes. In Experimental Example 2, the laser light energy is 400 W, and the rotation speed is 2.6 mm/s. After at least one rotation, the final stage reduces energy step by step. The first order energy is 350 W, the second order energy is 300 W, and the order maintenance time is 0.03 s or more. Can eliminate holes. In Experimental Example 3, the laser light energy is 600 W, and the rotation speed is 4.4 mm/s. After at least one turn, the tail end gradually reduces energy. The first order energy is 450 W, the second order energy is 375 W, and the third order energy is 300 W. The time is maintained for more than 0.1s to eliminate holes. In Experimental Example 4, the laser light energy is 540 W, and the rotation speed is 4.4 mm/s. After at least one rotation, the energy is gradually reduced in the final stage. The first-order energy is 500 W, the second-order energy is 460 W, and the third-order energy is 420 W. The fourth-order energy is 380W, the fifth-order energy is 340W, and the sixth-order energy is 300W. The time of each step is maintained for more than 0.05s, which can eliminate the holes.

In addition, the laser welding apparatus and method of the present invention are not limited to the above experimental data, the energy of the laser light can be up to 3000 W, the rotation speed can be 1 mm/above, and the maintenance time of each step can be 0.5 μs or more.

In summary, the laser welding apparatus and method of the present invention mainly controls the laser light energy to be slowly lowered in at least one step manner at the end of the welding process, thereby preventing the conventional technique from being performed in order to avoid unevenness of the welding surface. The vehicle repair method can avoid the problem that the previous laser welding will produce holes at the end of the welding.

The above-described embodiments are merely illustrative of the effects of the present invention, and are not intended to limit the scope of the present invention, and those skilled in the art can modify and modify the above-described embodiments without departing from the spirit and scope of the present invention. Moreover, the number of structures in the above embodiments is merely illustrative, and Not used to limit the case. Therefore, the scope of protection of the rights in this case should be listed in the scope of the patent application mentioned later.

11, 12‧‧‧Wears to be welded

111, 121‧‧‧ welding surface

13‧‧‧ joint

2‧‧‧Fixed unit

21‧‧‧Clamping device

3‧‧‧Laser unit

30‧‧‧Laser light

31‧‧‧Laser source

32‧‧‧welding head

4‧‧‧Blowing unit

5‧‧‧Control unit

51‧‧‧ Controller

Claims (16)

A laser welding apparatus includes: a fixing unit for fixing two objects to be welded having a welding surface, the fixing unit and the two welding objects being joined to each other and rotating synchronously; the laser unit Providing a laser beam to illuminate a joint of the welding surfaces of the two workpieces to be joined to each other for performing a welding process; and a blowing unit for engaging the joint of the two objects to be welded during the welding process Providing a shielding gas; and a control unit for controlling the energy of the laser light such that the energy of the laser light is decremented in at least one order when the welding process is performed to the end. The laser welding apparatus of claim 1, wherein the control unit is a controller electrically connected to the laser unit to control the energy of the laser light provided by the laser unit. The laser welding apparatus of claim 1, wherein the control unit comprises an optical lens set and a controller, the optical lens set is disposed between the laser unit and the two to-be-welded materials, to The controller adjusts the optical mirror to control the energy of the laser light. The laser welding apparatus of claim 3, wherein the optical lens set is used to adjust the direction of the laser light and the spot size. The laser welding apparatus of claim 1, wherein the control unit is further configured to set an initial energy and a final energy of the laser light according to the initial energy and the final energy. Get one in An inter-value energy, which in turn is set to a first-order energy, and an average for assigning a first-order number to the energy range of the intermediate-value energy to the end-order energy according to the order to the first of the order From the order to the last stage. The laser welding apparatus of claim 1, wherein the fixing unit comprises two clamping devices for respectively clamping the two objects to be welded and bonding the two objects to be welded to each other with respective welding faces. Rotate synchronously. The laser welding apparatus of claim 1, wherein the fixing unit comprises a positioning device for inserting the two objects to be welded therein and engaging each other with respective welding faces, the positioning device A welding window is included to expose the joint of the two objects to be welded, and the laser light is used to perform the welding process on the joint. The laser welding apparatus of claim 1, wherein the energy of the laser light is 3000 W or less. The laser welding apparatus of claim 1, wherein the rotational speed of the two objects to be welded is 1 mm/s or more. The laser welding apparatus of claim 1, wherein the time of each step is maintained for 0.5 μs or more. The laser welding apparatus of claim 1, wherein the shielding gas is helium, neon, or argon. A laser welding method comprises the steps of: providing two workpieces to be welded having a welding surface, respectively, and joining the two welding objects to each other to form a joint; Irradiating the joint of the two objects to be welded with a laser to perform a soldering process; during the soldering process, providing a shielding gas to the joint, and simultaneously rotating the two objects to be irradiated for the laser to illuminate the joint At one turn; and when the welding process is advanced to the end, the energy of the laser light is controlled to decrease in at least one order. The laser welding method of claim 12, wherein the step of providing a shielding gas to the joint comprises: providing the shielding gas to the joint when the laser light illuminates the joint; When the laser light illuminates one of the joints, the laser light is stopped and the supply of the shielding gas is stopped. The laser welding method of claim 12, further comprising: setting an initial energy and a final energy of the laser light to obtain an intermediate energy according to the initial energy and the final energy, The intermediate value energy is then set to the first order energy. The laser welding method of claim 14, further comprising setting an order to equally distribute the energy of the intermediate value energy to the end energy according to the order to the first order to the last order. The laser welding method according to claim 12, wherein the energy of the laser light is 3000 W or less, the rotation speed of the two objects to be welded is 1 mm/s or more, and the time of each step is maintained for 0.5 μs or more.