Device for the flexible placement of differently shaped welding studs and welding stud holder designed as a gripping pliers

Abstract

Device (100) for flexibly placing differently designed welding studs (500) on a component (600), comprising: - a stud magazine (200) with several feeding devices (210a-g) for providing different welding stud types, wherein each feeding device (210a-g) has a transfer point (211a-g) for the individual transfer of a welding stud (500) of a specific welding stud type; and - a welding robot (300) on whose arm (310) a stud welding head (400) is arranged, which has a welding stud holder (410) designed as a gripper;wherein, in order to grip a welding stud (500) of a specific welding stud type, the transfer points (211a-g) for the different welding stud types can be approached accordingly by the welding robot (300), so that with the welding stud holder (410) a welding stud (500) of a specific welding stud type to be inserted can be gripped at the corresponding transfer point (211a-g) of the stud magazine (200) and immediately afterwards welded in a defined position on the component (600).

Description

The invention relates to a device for flexibly setting differently shaped welding studs on a component, such as a vehicle body. The invention further relates to a welding stud holder designed as a gripper for use on a welding robot. A weld stud is a connecting element comprising a stud head and an axially extending connecting section (shank) arranged on the stud head. "Setting" refers to the metallurgical fastening of a weld stud to a component by creating a weld connection between the stud head and the component. Various methods for setting welding studs on a component are known in the prior art. As an example, reference is made to patent specification DE 100 07 837 A1, which describes a welding robot with a stud welding head attached to it. The welding studs to be set are individually picked up by a welding stud holder belonging to the stud welding head. Furthermore, feeding devices are known in the prior art with which the welding studs to be set can be fed to the stud welding head, in particular via a hose. DE 10 2005 044 367 A1 discloses a multi-layered, high-pressure-resistant and vibration-damping hose and a method for its manufacture. The hose combines elastomeric materials with reinforcing layers to improve pressure resistance, vibration damping and service life, particularly in automotive and industrial applications. DE 25 03 079 A1 relates to a device for connecting pipelines using an elastic, expandable sealing element. In particular, a detachable pipe connection is described in which an elastic sealing element is deformed by axial pressure or tension, causing it to expand radially and create a tight, mechanically stable connection between two pipe ends. German patent DE 102 23 154 A1 discloses a coolant pump for motor vehicles that includes a pre-formed leakage reservoir. The reservoir serves to collect escaping coolant in a controlled manner and to make leaks detectable at an early stage. A manufacturing process for such a leakage reservoir is also described. The aim is to increase operational reliability and simplify the diagnosis of leaks. DD 2 76 256 A1 discloses a pipe coupling with an elastic sealing element that expands under axial force. Axial compression causes the sealing element to expand radially and press against the inner wall of a pipe, creating a detachable, leak-proof, and mechanically stable pipe connection. The design allows for easy assembly without complex tools and is particularly suitable for pipelines that require frequent disconnection or maintenance. The invention is based on the objective of providing a device for the flexible placement of differently shaped welding studs on a component. This problem is solved by a device according to the invention with the features of claim 1. The solution to the problem extends to a pincer-like welding stud holder according to the invention (a welding stud holder designed as gripping pliers). Preferred embodiments and configurations for both aspects of the invention are described analogously in the dependent claims and the following explanations. The device according to the invention for flexibly placing differently designed welding studs on (at least) one component (or workpiece) comprises: - a stud magazine with several feeding devices for providing different types of welding studs, wherein each feeding device has a transfer point for the individual transfer of a welding stud of a specific welding stud type; and - a welding robot, on whose arm a stud welding head is arranged, which has a welding stud holder designed as a gripper, with which a welding stud of a specific welding stud type to be placed can be gripped at the corresponding transfer point of the stud magazine and immediately afterwards welded to the component in a defined position. Flexible stud placement means that the placement positions on the component are not rigidly fixed, but can be individually specified for each component. The different stud types that can be flexibly placed using the device according to the invention differ particularly in shank length and / or shank diameter. Furthermore, the different stud types can also differ with regard to head geometries and / or material (including coatings). The component in question is specifically a vehicle body for a passenger car. The feeding devices could be, for example, feed rails, feed hoses, or similar equipment. The welding robot is generally a programmable multi-axis handling device, such as an industrial robot or a gantry robot. It is envisaged that a stud welding head with a welding stud holder designed as a gripper is arranged on the robot arm (or similar) of the welding robot. This gripper can be moved in a defined manner in space by the welding robot. Such a gripper has two gripping arms that are movable relative to each other, with corresponding gripping jaws attached to them, between which a welding stud to be inserted can be clamped and thus gripped. A welding stud gripped by the stud holder, which is designed as a gripping tool, can be welded directly to the component, i.e., without prior setting down, regripping, or the like. The welding is achieved in particular by arc welding initiated by an electric current, for which an arc is generated between the welding stud and the component in a known manner by lift ignition (lifting the welding stud from the component surface). The welding current flows through the welding stud via at least one of the gripping jaws. The device according to the invention enables the automated, rapid, precise, and flexible placement of differently shaped welding studs on a component, in particular by successively picking up several welding studs, especially those of different shapes, from the stud magazine using the welding stud holder designed as a gripper and immediately welding them to the component in defined positions, for which the welding robot is programmed accordingly. (The programming can, for example, also be taken from a CAD data set for the component.) The device according to the invention is ideally suited for small series production and prototype manufacturing, especially in automotive engineering, and can replace the still common practice of setting welding studs by hand using templates. Preferably, the welding stud holder, designed as a gripping pliers, has two corresponding gripping jaws, each with several opposing recesses for gripping welding studs of different diameters. The recesses are preferably arc-shaped and, in particular, essentially semicircular, and can be adapted to a specific stud diameter (shank diameter). It is particularly preferred that the recesses in the gripping jaws are designed with knurling (ridges formed by grooves). When gripping a weld stud, which may in particular be a threaded stud, the knurling enables a positive locking connection between the gripping jaws and the gripped weld stud. An actuation mechanism for the welding stud holder, designed as a gripper, can be arranged on the arm of the welding robot to actuate the gripping jaws. The actuation mechanism can be integrated into the stud welding head and / or the gripper-like welding stud holder. Preferably, the actuation mechanism also includes an electric motor drive. A pneumatic or hydraulic drive can also be provided instead of an electric motor drive. In particular, it is provided that, through the kinematic design of the actuation mechanism, the positioning movements and forces generated by the drive are converted into the required gripping jaw movements and clamping forces that can be generated between the gripping jaws. The feed devices of the bolt magazine can each be equipped with a spring-loaded holding mechanism at their transfer points. This holding mechanism prevents welding bolts from falling out and allows the removal of a welding bolt (gripped by the welding head, which is designed as a gripping pliers). Such a spring-loaded holding mechanism could, for example, be a spring-loaded pressure piece extending into the feed channel at the transfer point, which exerts a holding force on the welding bolt located at the transfer point. Preferably, at least one feeding device and in particular all feeding devices of the bolt magazine are designed with a singulation mechanism in order to feed the welding bolts individually to the transfer point and to enable, due to the best possible accessibility, an unproblematic gripping and removal of a welding bolt (with the welding bolt holder designed as a gripping pliers). A welding stud holder according to the invention, designed as a gripping pliers (hereinafter also referred to as a pliers-like welding stud holder), has two corresponding gripping jaws, which are designed with several recesses, each pair opposing each other, for gripping welding studs of different diameters. Preferably, there are two pairs of recesses, so that two different types of welding studs with different diameters can be gripped with this pliers-like welding stud holder. The gripping jaws are preferably made of an electrically conductive material, such as, in particular, a copper- or brass-containing material. They are preferably of a solid design. The movement of the gripping jaws can be scissor-like, for which a scissor-like actuating mechanism may be provided. However, it is particularly preferred that the gripping jaws are not moved in a scissor-like manner, but rather actuated (i.e., moved) by a wedge slide, for which purpose they are pivotably mounted or supported, in particular, by means of separate joints. The invention is explained in more detail below by way of example and in a non-limiting manner with reference to the schematic figures. However, the features shown in the figures and / or explained below can be general features of the invention, independent of specific combinations of features. Fig. 1 shows a device according to the invention. Fig. 2 shows a pincer-like welding stud holder in a side view. Fig. 3 shows the pincer-like welding stud holder from Fig. 2 in a top view. Fig. 1 shows a device 100 according to the invention, which has a stud magazine 200 with several rail-like feed devices 210a-g for providing welding studs 500 of different welding stud types. Each feed device 210 can provide a specific welding stud type. Each feed device 210 has a transfer point 211a-g for the individual transfer of a specific welding stud type. The transfer points 211a-g can be equipped with a spring-operated holding mechanism (or the like) to prevent the welding studs 500 from falling out uncontrolled. Reference numeral 215 denotes, for example, electrically or pneumatically actuated singulation mechanisms. The various welding studs 500 are fed by the rail-like feeding devices 210 by rolling motion. Alternatively, a sliding or pushing feed is also possible (with horizontal, suspended, or even vertical welding studs, in particular such that the stud heads point downwards and the shanks upwards). The device 100 further comprises a welding robot 300, on whose arm 310 a stud welding head 400 is arranged, which has a stud holder 410 designed as a gripping tool. With the gripping stud holder 410, a stud 500 of a specific stud type can be gripped at the corresponding transfer point 211a-g of the stud magazine 200. To pick up or grip a stud 500 of a specific stud type, the transfer points 211a-g for the different stud types can be approached accordingly, which is accomplished by the welding robot 300. Immediately after gripping, the gripped stud 500 is welded in a defined position to a component 600. The component 600, which is, for example, a vehicle body, is located in a defined position and orientation relative to the welding robot 300. Fig. 2 shows a pincer-like welding stud holder 410 according to the invention. The welding stud holder 410 has two gripping arms 411A and 411B with gripping jaws 412A and 412B arranged thereon. The gripping arms 411A and 411B, which are essentially identical in design, are pivotably attached to supports 418A and 418B via joints 417A and 417B, which in turn are attached to a flange plate 419. The opposing gripping jaws 412A and 412B can perform opening and closing movements (as illustrated by the arrows) controlled by the wedge slide 416, which is actuated by a drive mechanism (not shown). An actuating mechanism for the pincer-like welding stud holder 410 for actuating or moving and applying force to the gripping arms 411A and 411B or the gripping jaws 412A and 412B can also be implemented in other ways. As can be seen in Fig. 3, the corresponding gripping jaws 412A and 412B are designed with several pairs of opposing, essentially semicircular recesses 413A / 413B and 414A / 414B, which are adapted to a specific weld stud diameter and thus serve to securely (and securely) grip weld studs 500 with different diameters (e.g., M8 and M10 or M6 and M8). Furthermore, the shape of the recesses 413A / 413B and 414A / 414B, respectively, and the weld studs 500 being gripped allows the surface pressures to be kept low despite high clamping forces, thereby significantly reducing the risk of damage to the weld studs, especially if they are threaded studs. The symmetrical recesses 413A / 413B and 414A / 414B in the gripping jaws 412A and 412B can have knurling 415 to enable a positive locking mechanism, especially when gripping threaded bolts (where the threaded bolt is gripped at the threaded shank), and to increase the safety against loss, especially during rapid traversing movements of the welding head 400. Reference symbol list 100 Device 200 Bolt magazine 210 Feeding device 211 Transfer point 215 Singulation mechanism 300 Welding robot 310 Robot arm 400 Stud welding head 410 Pliers-like welding stud holder 411 Gripping arm 412 Gripping jaws 413 Recess 414 Recess 415 Knurling 416 Wedge slide 417 Joints 418 Support 419 Flange 500 Welding stud 600 Component (workpiece)

Claims

Device (100) for flexibly placing differently designed welding studs (500) on a component (600), comprising: - a stud magazine (200) with several feeding devices (210a-g) for providing different welding stud types, wherein each feeding device (210a-g) has a transfer point (211a-g) for the individual transfer of a welding stud (500) of a specific welding stud type; and - a welding robot (300) on whose arm (310) a stud welding head (400) is arranged, which has a welding stud holder (410) designed as a gripper;wherein, in order to grip a welding stud (500) of a specific welding stud type, the transfer points (211a-g) for the different welding stud types can be approached accordingly by the welding robot (300), so that with the welding stud holder (410) a welding stud (500) of a specific welding stud type to be inserted can be gripped at the corresponding transfer point (211a-g) of the stud magazine (200) and immediately afterwards welded in a defined position on the component (600). Device (100) according to claim 1, characterized in that the welding stud holder (410) designed as a gripping pliers has two corresponding gripping jaws (412A, 412B) which are designed with several recesses opposite each other in pairs for gripping welding studs (500) with different diameters, wherein two pairs of recesses (413A, 413B; 414A, 414B) are provided so that two welding stud types with different diameters can be gripped. Device (100) according to claim 2, characterized in that the recesses (413A, 413B; 414A, 414B) in the gripping jaws (412A, 412B) are formed with knurling (415). Device (100) according to one of the preceding claims, characterized in that an actuating mechanism for the welding stud holder (410) designed as a gripper is further arranged on the arm of the welding robot (310). Device (100) according to claim 4, characterized in that the actuating mechanism comprises an electromotor drive. Device (100) according to one of the preceding claims, characterized in that the feeding devices (210a-g) of the bolt magazine (200) are designed at the transfer points (211a-g) with spring-operated holding mechanisms which prevent welding bolts (500) from falling out, but allow the removal of a gripped welding bolt (500). Device (100) according to one of the preceding claims, characterized in that at least one feeding device (210a-g) of the bolt magazine (200) is designed with a singulation mechanism (215) to feed the welding bolts (500) individually to the transfer point (211a-g) and to enable unproblematic gripping and removal of the welding bolt (500) there. Pliers-like welding stud holder (410) for use on a welding robot (300) in a device (100) according to one of the preceding claims 2 to 7, characterized in that it has two corresponding gripping jaws (412A, 412B) which are formed with several recesses opposite each other in pairs for gripping welding studs (500) with different diameters, wherein two pairs of recesses (413A, 413B; 414A, 414B) are provided so that two welding stud types with different diameters can be gripped. Pliers-like welding stud holder (410) according to claim 8, characterized in that the gripping jaws (412A, 412B) are formed from an electrically conductive material, such as in particular a copper- or brass-containing material. Pliers-like welding stud holder (410) according to claim 8 or 9, characterized in that it has a wedge slide (416) for actuating the gripping jaws (412A, 412B).

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