Laser welding system with plasma protection

Abstract

A laser welding system for joining a first workpiece to a second workpiece includes a laser welder configured to emit a laser beam at a power to form a weld at a weld location joining the first workpiece and the second workpiece. The laser welding system includes a plasma shield clamp coupled to a surface of at least the first workpiece. The plasma shield clamp defines an opening configured to receive the laser beam. The opening has an outer rim surrounding and spaced apart from the weld. The plasma shield clamp has a height above the surface of at least the first workpiece around the outer rim of the opening, the height being defined based on the power of the laser beam.

Description

Technical Field

[0001] The technical field generally relates to laser welding, and more specifically to laser welding systems with plasma protection to ensure adequate weld penetration depth. Background Technology

[0002] In laser welding, a high-density light source is used to melt the materials of the parts to be joined. The parts are placed in near contact with each other, and a laser beam is guided by a laser welding machine to irradiate the parts and fuse them together. At the point where the laser beam intersects the parts, a pool of molten material is formed, mixing the materials of the parts being joined together. In some cases, both molten material and metal vapor may form during laser welding. Metal vapor, for example, may displace areas of molten material in the weld pool at the point where the laser beam enters the parts to form a keyhole. Furthermore, during the welding process, metal vapor may condense into small particles in the form of plumes. These plumes can interfere with the laser beam, and the small particles may also aggregate into larger particles, which can also attenuate the laser beam. Generally, it is desirable to remove the plumes to ensure the laser beam is not affected. However, a hot welding plasma can form above the keyhole, which helps conserve the heat energy of the keyhole. Removing the welding plasma above the keyhole may lead to reduced stability of the keyhole opening, reduced penetration depth, or inconsistent weld formation.

[0003] Therefore, it is desirable to provide a laser welding system with plasma protection, which enables the removal of plumes while providing improved weld penetration depth and weld uniformity. Furthermore, other desirable features and characteristics of the invention will become apparent from the following detailed description and appended claims, taken in conjunction with the accompanying drawings and the foregoing technical and background information. Summary of the Invention

[0004] According to various embodiments, a laser welding system is provided for joining a first workpiece to a second workpiece. The laser welding system includes a laser welder configured to emit a laser beam at a power level to form a weld at a welding location joining the first workpiece and the second workpiece. The laser welding system includes a plasma protective clamp coupled to at least a surface of the first workpiece. The plasma protective clamp defines an opening configured to receive the laser beam. The opening has an outer edge surrounding and spaced apart from the weld. The plasma protective clamp has a height above at least the surface of the first workpiece about the outer edge of the opening, the height being defined based on the power of the laser beam.

[0005] The height is 3 mm to 5 mm, and the power of the laser beam is greater than 3 kW. The height is 5 mm to 10 mm, and the power of the laser beam is less than 3 kW. The laser welding system includes: an auxiliary gas system configured to guide gas flow above at least the surface of the first workpiece, and the height of the plasma protective fixture configured to suppress gas flow from disturbing the welding plasma at the welding position. The plasma protective fixture defines a plurality of openings spaced apart from a first fixture side to a second fixture side. The welding position is a first surface of the first workpiece. The first workpiece is joined to the second workpiece using an overlap joint. The openings are rectangular, and the weld is a linear pin weld formed along a welding path. The linear pin weld is centered in the opening, and the auxiliary gas system is configured to guide gas flow in a direction parallel to the welding path, such that the gas flow follows the welding path. The welding position is a first surface of the first workpiece, and the first workpiece is joined to the second workpiece using an overlap joint. The openings are rectangular. The weld is at least one spot weld, and the at least one spot weld is located within the opening. The plasma protection fixture includes a coupling system configured to apply pressure to at least the first workpiece. The plasma protection fixture defines a fixture hole, and the coupling system includes a mechanical fastener configured to be received through the fixture hole to apply pressure to at least the first workpiece. The mechanical fastener is a turn screw or a spring pin. The laser welder is operable in both keyhole welding mode and conduction welding mode, and the height above the surface of at least the first workpiece about the outer edge of the opening is defined based on either the keyhole welding mode or the conduction welding mode. The welding location is the surface of the first workpiece near a first end of the first workpiece and the second surface of the second workpiece near a second end of the second workpiece, and the first workpiece is joined to the second workpiece using a butt joint. The welding location is the first surface of the first workpiece, and the first workpiece is joined to the second workpiece using an overlap joint. The plasma protection fixture includes at least one handle.

[0006] A laser welding system for joining a first workpiece to a second workpiece is also provided. The laser welding system includes a laser welder configured to emit a laser beam at a power level to form a weld joining the first and second workpieces along a welding path. The laser welder is operable in welding modes, including a keyhole welding mode and a conduction welding mode. The laser welding system includes an auxiliary gas system configured to guide gas flow in a direction parallel to the welding path above at least the surface of the first workpiece, such that the gas flow follows the welding path. The laser welding system includes a plasma protection fixture defining a clamping hole and a coupling system, the coupling system including a mechanical fastener configured to be received through the clamping hole and configured to apply pressure to the surface of at least the first workpiece. The plasma protection fixture defines an opening configured to receive the laser beam, and the coupling system is defined around an outer edge of the opening. The outer edge of the opening surrounds and is spaced apart from the welding path, the welding path being defined within the opening. The plasma protection fixture has a height above at least the surface of the first workpiece around the outer edge of the opening, the height being defined based on the welding mode, and the height of the plasma protection fixture is configured to suppress the flow of the gas along the welding path that would disturb the welding plasma.

[0007] The height is 3 mm to 5 mm, and the welding pattern is the keyhole welding pattern. The height is 5 mm to 10 mm, and the welding pattern is the conductive welding pattern. The plasma protection fixture defines a plurality of openings spaced apart from the first fixture side to the second fixture side. The openings are rectangular, and the welding path is linear to form a pin weld. The mechanical fastener is a rotating screw, a spring pin, or a spring offset pin. Attached Figure Description

[0008] Exemplary embodiments will be described below in conjunction with the following figures, wherein the same numerals denote the same elements, and wherein:

[0009] Figure 1 This is a schematic partial cross-sectional view of a laser welding system according to various embodiments, the laser welding system including an exemplary plasma protection fixture for plasma protection, wherein, along... Figure 3 The plasma protection fixture, the first workpiece, and the second workpiece are shown in the cross section taken from line 1-1;

[0010] Figure 2 It is along Figure 3 The line 2-2 cut off, Figure 1A schematic partial cross-sectional view of a laser welding system, in which the laser welding machine of the laser welding system is removed for clarity;

[0011] Figure 3 yes Figure 1 A schematic perspective view of the plasma protection fixture, the first workpiece, and the second workpiece, wherein the laser welding machine of the laser welding system is removed for clarity.

[0012] Figure 4 It is used for utilization Figure 1 A schematic perspective view of another exemplary plasma-protected fixture, a first workpiece, and a second workpiece for laser welding using a laser welding machine, wherein the laser welding machine has been removed for clarity;

[0013] Figure 5 It is used for utilization Figure 1 A schematic perspective view of another exemplary plasma-protected fixture, a first workpiece, and a second workpiece used in laser welding with a laser welding machine, wherein the laser welding machine has been removed for clarity; and

[0014] Figure 6 This is a schematic perspective view of a plasma protection fixture used at an exemplary welding position, which is defined for utilizing... Figure 1 The laser welding machine is used to laser weld the first and second workpieces, but for clarity, the laser welding machine has been removed. Detailed Implementation

[0015] The following detailed description is exemplary in nature only and is not intended to limit application and use. Furthermore, it is not intended to be bound by any express or implied theory set forth in the foregoing technical fields, background art, summary of the invention, or the following detailed description. Additionally, those skilled in the art will understand that embodiments of this disclosure can be practiced in combination with any number of systems, and the systems described herein are merely exemplary embodiments of this disclosure.

[0016] For the sake of brevity, conventional techniques related to signal processing, data transmission, signaling, control, machine learning models, and other functional aspects of the system (and its various operating components) will not be described in detail herein. Furthermore, the connecting lines shown in the various figures included herein are intended to represent example functional relationships and / or physical couplings between various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in the embodiments of this disclosure. As used herein, the term “substantially” means within 10% to account for manufacturing tolerances, and the term “approximately” means within 10% to account for manufacturing tolerances.

[0017] Reference Figure 1The image illustrates a laser welding system 100. In one example, the laser welding system 100 includes a laser welder or laser welding machine 102, a plasma protective fixture 104, a first workpiece 106, and a second workpiece 108. It should be noted that although the plasma protective fixture 104 is described herein as being used with the laser welding system 100, the plasma protective fixture 104 can be used with any suitable welding system. In one example, the laser welding machine 102 includes a light source 109, a reflector 110, optics 112, a power supply 114, and a controller 116. The controller 116 includes a processor and a memory storing executable instructions for the operation of the laser welding machine 102. The light source 109 is powered and controlled by the power supply 114 and the controller 116 to generate light entering a resonant cavity 118. This light is amplified and reflected by the reflector 110 and appears through the optics 112 as a converging laser beam 120 focused at a single point on the first workpiece 106. Laser welding machine 102 is configured to apply a laser beam 120 at the welding position to form a weld that joins a first workpiece 106 to a second workpiece 108. Generally, laser welding machine 102 can be controlled by controller 116 to produce welds of a predetermined type at the welding position, including but not limited to spot welds, pin welds, or stud welds. Figure 1 In the example of the pin weld shown, the laser welding machine 102 is controlled to move the laser beam through the first workpiece 106 along a predetermined linear welding path P, which is protected by a plasma-protected fixture 104. The laser welding machine 102 is also controlled by the controller 116 to operate in either a keyhole welding mode or a conduction welding mode. Generally, in conduction welding mode, the power of the laser beam 120 is low or less than that in keyhole welding mode, so that no keyhole is formed in conduction welding mode. In the example of the first workpiece 106 and the second workpiece 108 made of steel, in keyhole welding mode, the power of the laser beam 120 output by the laser welding machine 102 is greater than 3 kilowatts (kW). In the example of the first workpiece 106 and the second workpiece 108 made of steel, in conduction welding mode, the power of the laser beam 120 output by the laser welding machine 102 is less than 3 kilowatts (kW). Therefore, the laser welding machine 102 outputs a laser beam 120 at a first power (greater than 3 kilowatts (kW)) in keyhole welding mode, or at a second power (less than 3 kilowatts (kW)) in conduction welding mode. In this example, the laser power density of the laser welding machine 102 is greater than 100,000 watts per square centimeter (W / cm²). 2 It should be noted that, Figure 1 The illustration of the laser welding machine 102 is merely exemplary, as the light source 109 can be configured as a stand-alone device mounted on the floor, wherein an optical fiber delivers a laser beam 120 from the light source 109 to an optics device 112 for laser welding.

[0018] In one example, a keyhole welding mode is used to form a weld to join a first workpiece 106 and a second workpiece 108 along a straight line defined by a welding path P. A laser beam 120 is directed at the first workpiece 106. Generally, an optical element 112 is spaced apart from the surface 122 of the first workpiece 106, such that the laser beam 120 passes through the air space defined between the optical element 112 and the first workpiece 106. The first workpiece 106 and the second workpiece 108 are joined by a laser welding machine 102 along the welding path P. The laser beam 120 is guided along the welding path P to form a keyhole 126 and a molten pool 124. In this example, the keyhole 126 and the molten pool 124 unfold as the laser beam 120 travels along the linear welding path P. The laser beam 120 may travel along the linear welding path P with or without oscillation in the lateral and feed directions. The surface 122 of the first workpiece 106 directly struck by the laser beam 120 becomes heated and may evaporate. As the metal vapor leaves surface 122, it generates a recoil pressure that pushes the free surface of the molten pool 124 downward, forming a deep, narrow cavity known as keyhole 126. Keyhole 126 penetrates the molten material and is filled with welding plasma 125, which is ionized metal vapor. Welding plasma 125 is also present in the region above and around keyhole 126. The presence of hot welding plasma 125 above keyhole 126 helps conserve heat in the region of keyhole 126, which is beneficial to the stability of the laser welding process. Above surface 122, metal vapor and particles flow out from the molten pool 124 and keyhole 126 to form a plume 130, which is above the region of welding plasma 125 and further away from the hot molten pool 124 and keyhole 126. Plume 130 is cooler than welding plasma 125 and has particles at least or greater than 80 nanometers (nm), which may interfere with the laser beam 120 reaching the first workpiece 106. Particles in the plume 130 may also attenuate, scatter, or suppress the laser beam 120. Therefore, the laser energy reaching the surface 122 may be reduced and fluctuate, potentially failing to maintain the keyhole 126 in a stable state. This increases spatter and process instability, and may result in reduced weld penetration. In addition to suppressing the laser beam 120 through the plume 130, spatter contained within the plume 130 may also contaminate or damage the optics 112 of the laser welding machine 102, which is undesirable.

[0019] In one example, the laser welding system 100 includes a secondary gas system 140. Figure 2The auxiliary gas system 140 guides a laminar flow of gas F (such as air or other inert gas) in a direction parallel to the surface 122 of the first workpiece 106. In one example, the flow of gas F is parallel to the movement of the laser beam 120 along the welding path P. In other words, the auxiliary gas system 140 guides a laminar flow of gas F in a direction substantially parallel to the welding path P, such that the flow of gas F follows or flows against the welding path P. Figure 1 In the example, the welding path P is linear and extends into the page. Therefore, when the gas F follows the welding path P, the auxiliary gas system 140 directs the gas F into the page, or in the example where the gas F flows in the opposite direction to the welding path P, directs the gas F out of the page.

[0020] Reference Figure 2 In this example, the auxiliary gas system 140 is a blower or fan that outputs a flow of gas F at approximately 5 m / s to approximately 20 m / s in a direction parallel to the surface 122 of the first workpiece 106. The auxiliary gas system 140 guides the laminar flow of gas F substantially along the direction of the welding path P. Generally, the flow of gas F is output by the auxiliary gas system 140 such that gas F extends through a gas height 142 above the surface 122 of the first workpiece 106 in a vertical or Y direction. In one example, the gas height 142 is approximately 90 mm to approximately 110 mm. Generally, the gas height 142 is predetermined so that the flow of gas F can blow away the plume 130 generated during the laser welding of the workpieces 106, 108 from the path of the laser beam 120 toward the surface 122. By directing the flow of gas F toward the laser beam 120 in the direction of the welding path P and along the gas height 142, the obstruction of the welding plume 130 to the laser beam 120 during laser welding of workpieces 106 and 108 is significantly reduced. Therefore, reduced interference of the plume 130 with the laser beam 120 results in more consistent laser energy toward the surface 122, and a more consistent weld formed by the laser beam 120. In one example, the auxiliary gas system 140 is spaced a predetermined distance D from the first workpiece 106; however, generally, the auxiliary gas system 140 can be positioned anywhere that allows it to provide gas F at a predetermined speed, flowing in the same direction as or opposite to the welding path P.

[0021] Because the auxiliary gas system 140 guides gas F along the surface 122 of the first workpiece 106 at a gas height 142 without the plasma protection fixture 104, the gas F will disturb or displace the hot welding plasma 125 along the surface 122, which may affect the penetration depth 144. In this respect, the penetration depth 144 is defined by the depth of the keyhole 126. The hot welding plasma 125 helps maintain heat in the area surrounding the keyhole 126, which makes it possible to form a deeper keyhole 126. Disturbing or displacing the hot welding plasma 125 from the area surrounding the keyhole 126 lowers the temperature of the molten pool 124, which results in a shallower keyhole 126. A shallow keyhole 126, in turn, leads to a smaller penetration depth and may cause instability in the keyhole 126. Therefore, the plasma protection fixture 104 surrounds the welding path P to protect the welding plasma 125 from the influence of the auxiliary gas system 140.

[0022] In one example, refer to Figure 3The image shows a perspective view of a plasma protection fixture 104 coupled to a surface 122 of a first workpiece 106. The plasma protection fixture 104 is made of metal or a metal alloy and can be cast, forged, stamped, additively manufactured, etc. In one example, the plasma protection fixture 104 is substantially rectangular and includes a first fixture end 150 opposite a second fixture end 152, a first fixture side 154 opposite a second fixture side 156, and a first fixture face 158 opposite a second fixture face 160. The plasma protection fixture 104 also defines at least one opening 162 and at least one optional coupling system 164. The first fixture end 150 and the second fixture end 152 are each substantially smooth and flat. In one example, the first fixture side 154 includes a grippable portion or handle 166. In this example, the handle 166 extends upward and outward from the first fixture side 154 in a substantially L-shape. The handle 166 includes a base portion 168 extending outward from the first clamping side 154 and a gripping portion 170 extending outward away from the base portion 168. The handle 166 may be integrally formed with the plasma protection clamp 104, or may be coupled to the first clamping side 154 via welding, mechanical fasteners, or the like. The base portion 168 of the handle 166 extends along a first clamping surface 158 from a first clamping end 150 to a second clamping end 152 on the first clamping side 154, and the gripping portion 170 allows a user to hold the plasma protection clamp 104 to position it on the surface 122 of the first workpiece 106. It should be noted that the L-shape of the handle 166 is merely exemplary. Furthermore, it should be noted that the plasma protection clamp 104 may not necessarily include the handle 166 if necessary. Additionally, the second clamping side 156 may also include a handle extending upward and outward opposite the handle 166 of the first clamping side 154. The second clamping side 156 is substantially smooth and flat. The first clamping surface 158 is positioned close to the laser welding machine 102. Figure 1 Furthermore, when the plasma protection fixture 104 is coupled to the first workpiece 106 to form an overlapping joint, the second fixture surface 160 is positioned on the surface 122 of the first workpiece 106.

[0023] In this example, the plasma protection fixture 104 defines a single opening 162. The opening 162 is defined by passing through the plasma protection fixture 104 from the first fixture face 158 to the second fixture face 160. In this example, the opening 162 is defined offset between the first fixture side 154 and the second fixture side 156, or the opening 162 is defined closer to the second fixture side 156. It should be noted that the opening 162 can be defined at any predetermined location on the plasma protection fixture 104, passing through the first fixture face 158 and the second fixture face 160. In this example, the opening 162 is rectangular and has a pair of opposing first sides 172 and a pair of opposing second sides 174. The first sides 172 and the second sides 174 can be coupled together with rounded or chamfered corners, or they can be coupled together with square or 90-degree corners. The first length L1 of the first side 172 is different from and less than the second length L2 of each of the second sides 174. Generally, the lengths L1 and L2 of sides 172 and 174 are predetermined based on the weld size and include a safety envelope on both sides of the weld path P. Therefore, the first length L1 and the second length L2 are each predetermined to provide a safety envelope on both sides of the weld path P. For example, the first length L1 is approximately 5 mm to approximately 20 mm, while the second length L2 is approximately 10 mm to approximately 30 mm. The first side 172 is defined parallel to the first clamp end 150 and the second clamp end 152, while the second side 174 is defined parallel to the first clamp side 154 and the second clamp side 156. The first side 172 and the second side 174 cooperate to define the outer edge 176 of the opening 162. The outer edge 176 surrounds the welding location, in this example, the surface 122 of the first workpiece 106 used to form an overlapping joint between the first workpiece 106 and the second workpiece 108. The outer edge 176 of the opening 162 is spaced apart from the weld path P to provide a safety envelope. Because the user can center the weld on the welding path P within the outer edge 176 defined by sides 172 and 174, the outer edge 176 of the opening 162 can also serve as a guide for arranging the weld. Therefore, generally, the opening 162 of the plasma protection fixture 104 defines the welding path P of the weld, which is centered within the opening 162. It should be noted that, although not shown herein, side 172 may include markings to assist the user in centering the weld along the welding path P defined by the opening 162.

[0024] The outer edge 176 of the opening 162 also has a height 178, which in this example is the same along or around the outer edge 176. In other words, the first side 172 and the second side 174 each have a height 178. The height 178 is measured from the first clamping surface 158 to the second clamping surface 160, or the height 178 of the plasma-protected clamp 104 above the surface 122 of the first workpiece 106. In this example, the height 178 is defined based on the power of the laser beam 120. If the power of the laser beam 120 is greater than 3 kilowatts (kW), the height 178 of the outer edge 176 of the opening 162 is approximately 3 millimeters (mm) to approximately 5 millimeters (mm). If the power of the laser beam 120 output by the laser welding machine 102 is less than 3 kilowatts (kW), the height 178 of the outer edge 176 of the opening 162 is approximately 5 millimeters (mm) to approximately 10 millimeters (mm). In other words, the height 178 is defined based on the welding mode of the laser welding machine 102. If the laser welding machine 102 is in keyhole welding mode, the height 178 of the outer edge 176 of the opening 162 is approximately 3 mm to approximately 5 mm. If the laser welding machine 102 is in conduction welding mode, the height 178 of the outer edge 176 of the opening 162 is approximately 5 mm to approximately 10 mm. Therefore, the height 178 of the plasma protection fixture 104 above the surface 122 of the first workpiece 106 is based on the power of the laser beam 120 or on the welding mode of the laser welding machine 102. The height 178 of the opening 162 of the plasma protection fixture 104 suppresses the welding plasma 125 ( Figure 2 The weld is disturbed by the flow of gas F from the auxiliary gas system 140, which ensures weld consistency and penetration depth 144.

[0025] In this regard, if the height 178 of the outer edge 176 of the opening 162 is less than about 3 mm in keyhole welding mode or less than about 5 mm in conduction welding mode, the flow of gas F from the auxiliary gas system 140 will push the welding plasma 125 away from the area around the keyhole 126, resulting in an unstable keyhole 126 and reduced weld penetration. If the height 178 of the outer edge 176 of the opening 162 is greater than about 5 mm in keyhole welding mode or greater than about 10 mm in conduction welding mode, the flow of gas F from the auxiliary gas system 140 will be blocked by the plasma protection fixture 104, and there will not be enough airflow near the surface 122 to blow the plume 130 away from the front of the welding plasma 125, resulting in attenuation of the plume 130 against the laser beam 120 and inconsistent weld. In this example, the laser welding machine 102 ( Figure 1The plasma protection fixture 104 is in lock hole welding mode, and the height 178 of the outer edge 176 of the opening 162 is approximately 3 mm to approximately 5 mm.

[0026] The coupling system 164 helps to close any gaps that may exist between the first workpiece 106 and the second workpiece 108. It should be noted that the coupling system 164 can be optional. In one example, the coupling system 164 includes a plurality of identical mechanical fasteners 180. The plasma protection fixture 104 also includes a plurality of fixture holes 186. In this example, the fixture holes 186 are defined through the plasma protection fixture 104 from the first fixture face 158 to the second fixture face 160. The fixture holes 186 are defined to be adjacent to, next to, or close to the corner of the outer edge 176. Therefore, generally, the coupling system 164 is defined around the outer edge 176 of the opening 162. In this example, the plasma protection clamp 104 defines four clamp holes 186 for receiving a corresponding one of the four mechanical fasteners 180. However, the plasma protection clamp 104 may include any number of clamp holes 186 and mechanical fasteners 180, including but not limited to a single clamp hole 186 and a single mechanical fastener 180 associated with the opening 162.

[0027] In this example, each mechanical fastener 180 is a screw comprising multiple threads. Once the plasma protection clamp 104 is positioned on the surface 122 of the first workpiece 106, the mechanical fastener 180 is rotated to close any gap defined between the first workpiece 106 and the second workpiece 108. Figure 1 In other words, the coupling system 164 applies pressure to the first workpiece 106, pushing it toward the second workpiece 108 to ensure contact between them during the formation of the overlap joint. Therefore, the coupling system 164 helps eliminate any gaps between the first workpiece 106 and the second workpiece 108. The coupling system 164 also ensures proper positioning between the first workpiece 106 and the second workpiece 108 and also suppresses or prevents thermal deformation. Alternatively, each mechanical fastener 180 may include a spring pin positioned through a corresponding clamping hole 186 to apply pressure to the first workpiece 106, thereby closing any gaps between the first workpiece 106 and the second workpiece 108. As a further alternative, each mechanical fastener 180 may include a spring-biased pin positioned through a corresponding clamping hole 186 to apply pressure to the first workpiece 106, thereby closing any gaps between the first workpiece 106 and the second workpiece 108. Generally, the coupling system 164 can close any gaps that exist between the first workpiece 106 and the second workpiece 108. By closing the gaps, the quality of the weld is improved because any possible open areas between the first workpiece 106 and the second workpiece 108 are essentially eliminated.

[0028] Generally, the first workpiece 106 and the second workpiece 108 are each composed of a metal or metal alloy. The first workpiece 106 and the second workpiece 108 may be composed of the same metal or metal alloy, or they may be composed of different metals or metal alloys. The first workpiece 106 and the second workpiece 108 are shown herein as flat plates. However, it should be noted that the first workpiece 106 may include a component having any desired shape (such as rectangular, square, etc.), provided that the surface 122 of the first workpiece 106 is substantially flat for coupling to the plasma protection fixture 104. The second workpiece 108 may also include any desired shape; therefore, the first workpiece 106 and the second workpiece 108 shown herein are merely examples. Generally, the first workpiece 106 and the second workpiece 108 are automotive parts; however, the first workpiece 106 and the second workpiece may include other components.

[0029] It should be noted that the plasma protection fixture 104 can be configured in various ways depending on the type of weld to be formed between the first workpiece 106 and the second workpiece 108. For example, refer to Figure 4 The plasma protection fixture 300 is shown. Because the plasma protection fixture 300 and... Figures 1 to 3 The plasma protection fixture 104 is similar, therefore the same reference numerals will be used to denote the same or substantially the same parts. The plasma protection fixture 300 is used for utilizing the laser welding machine 102 ( Figure 1 The first workpiece 302 is laser welded to the second workpiece 304 to form an overlapping joint between the first workpiece 302 and the second workpiece 304. In this example, a plasma-protected fixture 300 is used to weld the first workpiece 302 to the second workpiece 304 via multiple pin welds.

[0030] The plasma protection fixture 300 is coupled to the surface 306 of the first workpiece 302. The plasma protection fixture 300 is made of metal or a metal alloy and can be cast, forged, stamped, additively manufactured, etc. In one example, the plasma protection fixture 300 is substantially rectangular and includes a first fixture end 310 opposite to the second fixture end 312, a first fixture side 314 opposite to the second fixture side 316, and a first fixture surface 318 opposite to the second fixture surface 320. The plasma protection fixture 300 also defines at least one opening 162 and at least one optional coupling system 322. The first fixture end 310 and the second fixture end 312 are each substantially smooth and flat. In one example, the first fixture side 314 includes a handle 166. In this example, the second fixture side 316 also includes a handle 326 opposite to the handle 166. The handle 326 extends upwardly and outwardly from the second fixture side 316 in a substantially L-shape. The handle 326 includes a base portion 328 extending upward from the second clamping side 316 and a gripping portion 330 extending outward from the base portion 328. The handle 326 may be integrally formed with the plasma protection clamp 300, or may be coupled to the second clamping side 316 via welding, mechanical fasteners, etc. The base portion 328 of the handle 326 extends from the first clamping end 310 to the second clamping end 312 along the first clamping surface 318 on the second clamping side 316, and the gripping portion 330 allows a user to hold the plasma protection clamp 300 to position the plasma protection clamp 300 on the surface 306 of the first workpiece 302. It should be noted that the L-shape of the handle 326 is merely exemplary. Furthermore, it should be noted that the plasma protection clamp 300 may not necessarily include handles 166 and 326 if necessary. The first clamping surface 318 is positioned close to the laser welding machine 102 ( Figure 1 Furthermore, when the plasma protection fixture 300 is coupled to the first workpiece 302, the second fixture surface 320 is positioned on the surface 306 of the first workpiece 302.

[0031] In this example, the plasma protection fixture 300 defines a plurality of openings 162, wherein each opening 162 is associated with a corresponding weld. Each opening 162 is defined by passing through the plasma protection fixture 300 from a first fixture face 318 to a second fixture face 320. In this example, the openings 162 are defined as being spaced apart between a first fixture side 314 and a second fixture side 316. It should be noted that the openings 162 can be defined at any predetermined location on the plasma protection fixture 300, passing through the first fixture face 318 and the second fixture face 320, to locate the welds of the workpieces 302, 304. Therefore, it should be noted that although the openings 162 are spaced approximately uniformly along the plasma protection fixture 300, the openings 162 can be spaced non-uniformly, arranged in clusters, or otherwise grouped in a predetermined manner to form a suitable weld between the workpieces 302 and 304. The first side 172 is defined parallel to the first clamp end 310 and the second clamp end 312, while the second side 174 is defined parallel to the first clamp side 314 and the second clamp side 316. The outer edge 176 surrounds the welding location, in this example, the surface 306 of the first workpiece 302 used to form an overlapping joint between the first workpiece 302 and the second workpiece 304. The outer edge 176 of each opening 162 is spaced apart from the welding path P to provide a safety envelope. Because a user can center the weld on the welding path P within the outer edge 176 defined by the respective opening 162, the outer edge 176 of each opening 162 can also serve as a guide for arranging the weld.

[0032] Each opening 162 also has an outer edge 176 with a height 178, which in this example is the same along the outer edge 176. In other words, the first side 172 and the second side 174 each have a height 178. The height 178 is measured from the first clamping surface 318 to the second clamping surface 320, or it is the height 178 of the plasma protective clamp 300 above the surface 306 of the first workpiece 302. As previously mentioned, the height 178 is defined based on the power of the laser beam 120 or the welding mode of the laser welding machine 102. Therefore, the height 178 of the plasma protective clamp 300 above the surface 306 of the first workpiece 302 is based on the power of the laser beam 120 or the welding mode of the laser welding machine 102. The height 178 of the opening 162 of the plasma protective clamp 300 suppresses the welding plasma 125 ( Figure 2 The laser welding machine 102 is disturbed by the flow of gas F from the auxiliary gas system 140. In this example, the laser welding machine 102 ( Figure 1 The plasma protection fixture 300 is in keyhole welding mode, and the height 178 of the outer edge 176 of each opening 162 is approximately 3 mm to approximately 5 mm.

[0033] The coupling system 322 helps to close any gaps that may exist between the first workpiece 302 and the second workpiece 304. It should be noted that the coupling system 322 may be optional. In one example, the coupling system 322 includes a plurality of mechanical fasteners 180. The plasma protection fixture 300 also includes a plurality of fixture holes 186. In this example, the fixture holes 186 are defined through the plasma protection fixture 300 from the first fixture face 318 to the second fixture face 320. The fixture holes 186 are defined to be positioned adjacent to, next to, or close to the corner of the outer edge 176 of each opening 162. In this example, the plasma protection fixture 300 defines ten fixture holes 186 for receiving a corresponding one of ten mechanical fasteners 180; however, the plasma protection fixture 300 may include any number of fixture holes 186 and mechanical fasteners 180, including but not limited to a single fixture hole 186 and a single mechanical fastener 180 associated with each opening 162. Generally, clamp holes 186 are defined on the plasma protection clamp 300 to be located at the corresponding four corners of each opening 162, and in this example, due to the positioning of the openings 162, some mechanical fasteners 180 may be associated with multiple openings 162.

[0034] Once the plasma protection fixture 300 is coupled or positioned on the surface 306 of the first workpiece 302, the mechanical fastener 180 is coaxially aligned with the fixture hole 186 and rotated to apply pressure to the first workpiece 302, thereby closing any gaps between the first workpiece 302 and the second workpiece 304. Alternatively, each mechanical fastener 180 may include a spring pin positioned through a corresponding fixture hole 186 to apply pressure to the first workpiece 302, thereby closing any gaps between the first workpiece 302 and the second workpiece 304. As a further alternative, each mechanical fastener 180 may include a spring-biased pin positioned through a corresponding fixture hole 186 to apply pressure to the first workpiece 302, thereby closing any gaps between the first workpiece 302 and the second workpiece 304. The coupling system 322 ensures that any gaps existing between the first workpiece 302 and the second workpiece 304 are substantially eliminated or closed. By closing the gaps, the quality of the weld is improved because any possible open areas between the first workpiece 302 and the second workpiece 304 are substantially eliminated.

[0035] The first workpiece 302 and the second workpiece 304 are each composed of a free metal or metal alloy. The first workpiece 302 and the second workpiece 304 may be composed of the same metal or metal alloy, or they may be composed of different metals or metal alloys. The first workpiece 304 and the second workpiece 304 are shown herein as elongated flat plates. However, it should be noted that the first workpiece 302 may include a component having any desired shape (such as rectangular, square, etc.), provided that the surface 306 of the first workpiece 302 is substantially flat for coupling to the plasma protection fixture 300. The second workpiece 304 may also include any desired shape; therefore, the first workpiece 302 and the second workpiece 304 shown herein are merely examples. Generally, the first workpiece 302 and the second workpiece 304 are automotive parts; however, the first workpiece 302 and the second workpiece 304 may include other components.

[0036] Furthermore, although the opening 162 of plasma protection fixture 104 and the opening 162 of plasma protection fixture 300 are shown herein as configured to accommodate a single weld along the welding path P, in other embodiments, the opening of the plasma protection fixture may accommodate more than one weld, and the plasma protection fixture may be shaped to correspond to the workpieces to be joined. For example, refer to... Figure 5 The plasma protection fixture 400 is shown. Because the plasma protection fixture 400 and... Figures 1 to 3 The plasma protection fixture 104 is similar to the plasma protection fixture 400, therefore the same reference numerals will be used to denote the same or substantially the same parts. The plasma protection fixture 400 is used with the laser welding machine 102 ( Figure 1 The first workpiece 402 is laser welded to the second workpiece 404 to form an overlapping joint between the first workpiece 402 and the second workpiece 404. In this example, a plasma-protected fixture 400 is used to weld the first workpiece 402 to the second workpiece 404 via multiple spot welds.

[0037] The plasma protection fixture 400 is coupled to surface 406 of the first workpiece 402. The plasma protection fixture 400 is made of metal or a metal alloy and can be cast, forged, stamped, additively manufactured, etc. In one example, the plasma protection fixture 400 is substantially V-shaped and includes a first fixture end 410 opposite to the second fixture end 412, a first fixture side 414 opposite to the second fixture side 416, and a first fixture face 418 opposite to the second fixture face 420. The plasma protection fixture 400 also defines one of a plurality of openings 162. In this example, the plasma protection fixture 400 does not include a coupling system; however, the plasma protection fixture 400 may include a coupling system, such as referenced... Figures 1 to 3 The coupling system discussed is 164.

[0038] The plasma protection fixture 400 may extend to the first fixture end 410 by a distance different from and less than the distance the plasma protection fixture 400 extends to the second fixture end 412, such that the first fixture end 410 and the second fixture end 412 are offset or unbalanced. The plasma protection fixture 400 may have a slight L-shape. The first fixture end 410 may define a groove 422 along the second fixture surface 420 to assist in coupling the plasma protection fixture 400 around workpieces 402, 404. The second fixture end 412 is substantially smooth and flat. The first fixture side 414 and the second fixture side 416 are each substantially smooth and flat at the second fixture end 412. The first fixture surface 418 at the second fixture end 412 is positioned close to the laser welding machine 102. Figure 1 When the plasma protection fixture 400 is coupled to the first workpiece 402, the second fixture surface 420 at the second fixture end 412 is positioned on the surface 406 of the first workpiece 402.

[0039] In this example, the plasma protection fixture 400 defines an opening 162, which in this example accommodates two weld seams. The opening 162 is defined by extending from a first fixture face 418 to a second fixture face 420 through the plasma protection fixture 400. In this example, the opening 162 is defined near the second fixture end 412. It should be noted that the opening 162 can be defined at any predetermined location on the plasma protection fixture 400, through the first fixture face 418 and the second fixture face 420, to locate the weld seams of workpieces 402, 404. A first side 172 is defined parallel to the first fixture side 414 and the second fixture side 416, while a second side 174 is defined parallel to the second fixture end 412. An outer edge 176 surrounds the welding location, in this example, the surface 406 of the first workpiece 402 used to form an overlapping joint between the first workpiece 402 and the second workpiece 404. In this example, the weld formed at the welding position includes two spot welds formed at two weld points P2 to couple the first workpiece 402 to the second workpiece 404. An outer edge 176 is spaced from the weld points P2 to provide a safety envelope. Because the user can center the weld points P2 within the outer edge 176 defined by the opening 162, the outer edge 176 of the opening 162 can also serve as a guide for arranging the welds. It should be noted that, alternatively, a single pin weld can be formed at the welding position within the opening 162 of the plasma protection fixture 400.

[0040] The outer edge 176 of the opening 162 also has a height 178, which in this example is the same along the outer edge 176. In other words, the first side 172 and the second side 174 each have a height 178. The height 178 is measured from the first clamping surface 318 to the second clamping surface 320, or it is the height 178 of the plasma protection fixture 400 above the surface 406 of the first workpiece 402. As previously stated, the height 178 is defined based on the power of the laser beam 120, and the height 178 of the plasma protection fixture 400 above the surface 406 of the first workpiece 402 is based on the power of the laser beam 120. The height 178 of the opening 162 of the plasma protection fixture 400 suppresses the welding plasma 125 ( Figure 2 The laser welding machine 102 is disturbed by the flow of gas F from the auxiliary gas system 140. In this example, the laser welding machine 102 ( Figure 1 The plasma is in conductive welding mode, and the height 178 of the outer edge 176 of the opening 162 of the plasma protective fixture 400 is approximately 5 mm to approximately 10 mm.

[0041] The first workpiece 402 and the second workpiece 404 are each composed of a free metal or metal alloy. The first workpiece 402 and the second workpiece 404 may be composed of the same metal or metal alloy, or they may be composed of different metals or metal alloys. In this example, the first workpiece 402 is an elongated panel, while the second workpiece 404 is a mounting bracket. Generally, the first workpiece 402 and the second workpiece 404 are automotive parts; however, the first workpiece 402 and the second workpiece 404 may also include other components.

[0042] It should be noted that the plasma protection fixture 104 can be used to form welds at welding locations other than the surface 122 of the first workpiece 302. For example, see reference... Figure 6 The plasma protection fixture 104 is shown for use with a first workpiece 500 and a second workpiece 502. In this example, the plasma protection fixture 104 is used to laser weld the first workpiece 500 to the second workpiece 502, utilizing a laser welding machine 102 ( Figure 1 A butt joint is formed via pin welds. Figure 6 In the example, the first workpiece 500 includes a first workpiece end 504 opposite to the second workpiece end 506 and a first workpiece surface 508 opposite to the second workpiece surface 510. The first workpiece surface 508 and the second workpiece surface 510 each extend from the first workpiece end 504 to the second workpiece end 506. The second workpiece 502 includes a third workpiece end 512 opposite to the fourth workpiece end 514 and a third workpiece surface 516 opposite to the fourth workpiece surface 518. The third workpiece surface 516 and the fourth workpiece surface 518 each extend from the third workpiece end 512 to the fourth workpiece end 514.

[0043] In this example, the second workpiece end 506 abuts against or is directly adjacent to the third workpiece end 512 to form a mating joint that engages the first workpiece 500 to the second workpiece 502. Therefore, Figure 6 In this example, the welding locations are the first workpiece surface 508 of the second workpiece end 506 and the third workpiece surface 516 of the third workpiece end 512. A plasma protection fixture 104 is positioned on the first workpiece surface 508 of the first workpiece 500 near the second workpiece end 506 and the third workpiece surface 516 of the second workpiece 502 near the third workpiece end 512. An opening 162 of the plasma protection fixture 104 is centered between the second workpiece end 506 and the third workpiece end 512, such that a welding path P is defined along the adjacent ends 506, 512. The welding path P is linear to form a pin weld at the welding location. In this example, the coupling system 164 can be used to apply pressure to prevent thermal deformation between the first workpiece 500 and the second workpiece 502 during the laser welding process.

[0044] Therefore, plasma protection fixtures 104, 300, and 400 protect the welding plasma on surfaces 122, 306, and 406 of the first workpieces 106, 302, and 402. Figure 2 ) protected from auxiliary gas system 140 ( Figure 1 and Figure 2 The influence of this resulted in a weld penetration depth of 144 ( Figure 2 Improvements to the plasma protection fixtures 104, 300, 400, with a predefined height 178 based on the power of the laser beam 120 or the welding mode of the laser welding machine 102, ensure that the welding plasma 125 ( Figure 1The weld pool 124 is held in place, ensuring consistent weld formation along the entire keyhole 126. By providing plasma protection fixtures 104, 300, 400 and an auxiliary gas system 140, the plume 130 does not interfere with the laser beam 120, and the gas F does not interfere with the welding plasma 125, resulting in consistent weld formation and consistent penetration depth 144. By protecting the welding plasma 125, the weld pool 124 remains hot, enabling the formation of a deeper keyhole 126, thereby increasing the penetration depth 144. By utilizing the auxiliary gas system 140 to remove the plume 130, particles within the plume 130 do not interfere with the laser beam 120, thus ensuring the consistency of the laser beam 120 along the welding path P. It should be noted that the spacing and orientation of the openings 162 and 662 on the corresponding plasma protection fixtures 104, 300, and 400 can be any predetermined spacing and orientation that ensures, for example, the welds between the corresponding workpieces 106, 108, 302, 304, 402, and 404 meet predetermined strength requirements. Furthermore, the size of the opening 162 can be predetermined based on the size of the weld. Additionally, the shape of the plasma protection fixture can conform to the workpieces to be joined while maintaining a height 178 around the outer edge 176 of the opening 162.

[0045] It should be noted that, although in Figures 1 to 4 The welding path P is shown as linear, but it can have other shapes suitable for use within the opening 162. For example, the laser welding machine 102 outputs a laser beam 120 to form welds with stud shapes, C-shapes, circles, etc. Furthermore, the laser welding machine 102 can output a laser beam 120 that moves along the welding path P with or without oscillation. It should also be noted that although plasma protection fixtures 104, 300 are described herein as being used to form overlapping or butt joints, they can be used to form other types of joints between workpieces, including but not limited to lap joints, corner joints, etc. Additionally, plasma protection fixture 400 can also be used to form butt joints.

[0046] Although at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that numerous variations exist. It should also be understood that the exemplary embodiments or multiple exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of this disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing the exemplary embodiments or multiple exemplary embodiments. It should be understood that various changes may be made to the function and arrangement of the elements without departing from the scope of this disclosure as set forth in the appended claims and their legal equivalents.

Claims

1. A laser welding system for joining a first workpiece to a second workpiece, comprising: A laser welder configured to emit a laser beam at a power level to form a weld at a welding position that joins the first workpiece and the second workpiece. as well as A plasma protection fixture coupled to the surface of at least the first workpiece, the plasma protection fixture defining an opening configured to receive the laser beam, the opening having an outer edge surrounding and spaced apart from the weld, and the plasma protection fixture having a height above the surface of at least the first workpiece about the outer edge of the opening, the height varying based on the power of the laser beam, wherein the height is 3 to 5 millimeters if the power of the laser beam is greater than 3 kilowatts, and 5 to 10 millimeters if the power of the laser beam is less than 3 kilowatts.

2. The laser welding system of claim 1 further includes an auxiliary gas system configured to guide the flow of gas above at least the surface of the first workpiece, and the height of the plasma protection fixture is configured to suppress the flow of gas from disturbing the welding plasma at the welding position.

3. The laser welding system according to claim 1, wherein, The plasma protection clamp defines a plurality of openings spaced apart from a first clamp side to a second clamp side on the plasma protection clamp, and the plasma protection clamp includes at least one handle.

4. The laser welding system according to claim 2, wherein, The welding position is the first surface of the first workpiece, the first workpiece is joined to the second workpiece by an overlapping joint, the opening is rectangular, the weld is a linear pin weld formed along the welding path, the linear pin weld is centered in the opening, and the auxiliary gas system is configured to guide the flow of the gas in a direction parallel to the welding path, such that the flow of the gas follows the welding path.

5. The laser welding system according to claim 1, wherein, The welding position is the first surface of the first workpiece, the first workpiece is joined to the second workpiece by an overlapping joint, the opening is rectangular, the weld is at least one spot weld, and the at least one spot weld is located within the opening.

6. The laser welding system according to claim 1, wherein, The plasma protection fixture includes a coupling system configured to apply pressure to at least the first workpiece, the plasma protection fixture defining a fixture hole, the coupling system including a mechanical fastener configured to be received through the fixture hole to apply pressure to at least the first workpiece, and the mechanical fastener being a rotating screw or a spring pin.

7. The laser welding system according to claim 1, wherein, The laser welder is capable of operating in both keyhole welding mode and conductive welding mode. The height of the laser welder above at least the surface of the first workpiece around the outer edge of the opening is defined based on either the keyhole welding mode or the conductive welding mode. In the keyhole welding mode, the height is 3 to 5 millimeters, while in the conductive welding mode, the height is 5 to 10 millimeters.

8. The laser welding system according to claim 1, wherein, The welding positions are the surface of the first workpiece near the first end of the first workpiece and the second surface of the second workpiece near the second end of the second workpiece, and the first workpiece is joined to the second workpiece using a butt joint.

Images