Welding device for welding studs with gas distribution function

Abstract

The present invention relates to a welding device 100 for welding a weld stud 120 to a substrate along a weld axis 105 in a welding direction 110, the welding device including an inert gas cover 140 having an inert gas inlet 150 arranged in the form of a ring around the weld axis 105, an inert gas outlet 170, and an opening 180 facing the welding direction 110. The opening 180 has an opening diameter in a direction transverse to the welding direction 110, the inert gas inlet 150 being at an entrance distance ae to the opening 180 on the side opposite the welding direction 110, and the inert gas outlet 170 being at an exit distance aA from the opening 180 on the side opposite the welding direction 110. The welding device further includes a retention device 144 for retaining the weld stud 120 within the inert gas cover 140 during a welding operation. The retention device 144 has an outer diameter and a stud receiving portion having an inner diameter. The exit distance is at least half the difference between the opening diameter and the outer diameter or at least as great as the entrance distance.

Description

[Technical field]

[0001] The present invention relates generally to a welding device for welding a weld stud to a substrate (a fastened member) in a welding direction along a weld axis, and more particularly to a welding gun. [Background technology]

[0002] There are many known devices and methods for fastening different studs to a substrate for different applications. For example, the stud is brought into contact with the substrate and a current is applied thereto. For this purpose, the stud is held by a conductive stud holder. As soon as a current flows between the stud and the substrate, the stud is moved away from the substrate forming an arc. The released energy partially liquefies the material of the stud and the substrate. The current is then switched off and the stud is immersed in the liquefied material, which cools and solidifies. The stud is then connected to the substrate in an integrally joined state.

[0003] In order to provide the energy required to liquefy the stud and substrate materials in a sufficiently short time, devices are known that generate a current of very high current strength and supply it to the stud using an electric cable of a corresponding rating. In order to avoid oxidation of the liquefied material, it is known to fill the contact point between the stud and the substrate with an inert gas, which in this case flows through the weld point together with the liquefied material and displaces the oxygen present there from the ambient air under certain circumstances.

[0004] For example, for applications in construction or shipbuilding, studs of various sizes are used to fasten articles to substrates, with threads onto which the articles are screwed. Summary of the Invention [Problem to be solved by the invention]

[0005] It is an object of the present invention to provide a device which improves the fastening of a stud to a substrate. [Means for solving the problem]

[0006] This object is achieved using a welding device for welding a weld stud to a substrate along a weld axis in a welding direction, the welding device comprising an inert gas cover having an inert gas inlet arranged in the form of a ring around the weld axis, an inert gas outlet and an opening facing the welding direction, the opening having an opening diameter in a direction transverse to the welding direction, the inert gas inlet being at an inlet distance from the opening opposite the welding direction and the inert gas outlet being at an outlet distance from the opening opposite the welding direction, the welding device further comprising a holding device for holding the weld stud in the inert gas cover during the welding operation, the holding device having an outer diameter and a stud receptacle having an inner diameter, the outlet distance being at least half the difference between the opening diameter and the outer diameter. Similarly, this object is achieved when the outlet distance is at least as large as the inlet distance. The welding device is preferably formed as a welding gun. By arranging the inert gas inlet in the form of a ring and arranging the inert gas outlet at a distance from the opening, it is ensured that the inert gas flows uniformly from all directions radially to the weld point and then substantially axially away from the weld point.

[0007] An advantageous embodiment of the invention is characterized in that the outlet distance is at least half the difference between the opening diameter and the inner diameter or at least as large as the inlet distance. A further advantageous embodiment is characterized in that the outlet distance is at least half the difference between the opening diameter and the outer diameter and at least half the size of the inlet distance.

[0008] An advantageous aspect is characterized in that the inert gas inlet is directed onto a radially outer region of the opening in order to generate a flow of inert gas along the opening in a radial direction relative to the setting axis when the opening is covered.

[0009] An advantageous embodiment is characterized in that the inert gas inlet comprises an inlet opening in the form of a ring surrounding the welding axis. Another embodiment is characterized in that the inert gas inlet comprises a plurality of inlet openings arranged in the form of a ring around the welding axis.

[0010] An advantageous embodiment is characterized in that the inert gas outlet comprises a plurality of outlet openings arranged in the form of a ring around the welding axis. The inert gas outlets are preferably arranged offset from the inert gas inlet in a transverse direction to the welding axis. A further advantageous embodiment is characterized in that the inert gas outlets lead outwardly through the inert gas cover in a radial direction to the welding axis into the surrounding area.

[0011] The invention will now be explained in more detail on the basis of exemplary embodiments with reference to the drawings. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 shows a schematic diagram of a welding device. [Diagram 2] FIG. 2 is a partial longitudinal cross-sectional view showing a schematic representation of a welding device; [Diagram 3] FIG. 2 is a partial longitudinal cross-sectional view showing a schematic representation of a welding device; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In Fig. 1 a welding device 10 for welding a weld stud 20 to a substrate (part to be fastened) 30 is shown diagrammatically. The material of the weld stud 20 and of the substrate 30 are electrically conductive, in particular metallic. The welding device 10 comprises a welding gun 40 with a trigger switch 41 formed as a push button switch, a welding unit 50, a first electric cable 61, a second electric cable 62 with a connection terminal 63, an electric supply cable 64, for example as a power cable, an electric communication line 65, a gas reservoir 70 as a gas cylinder, a tubular gas supply line 71 and a gas hose 72.

[0014] The first cable 61 serves to supply the current to the welding stud 20 via the welding unit 50. The second cable 62 serves to electrically connect the substrate 30 to the welding unit 50 when the connection terminal 63 is clamped to the substrate 30. When the welding stud 20 comes into contact with the substrate 30, a circuit is closed, whereby a welding current, for example in the form of a direct or alternating current, can be applied to the welding stud 20 via the welding unit 50. For this, the welding gun 40 comprises a welding current contact element, not shown in FIG. 1. The welding unit 50 comprises a device (not shown) for converting the current from the supply cable 64 into a welding current, which device comprises, for example, electric capacitors, thyristors, bipolar transistors with insulated gate electrodes or other components from power electronics and also an associated control unit with a microprocessor, in order to provide the welding current at the desired voltage and current strength.

[0015] The gas supply line 71 and the gas hose 72 serve to supply inert gas from the gas reservoir 70 to the contact area between the weld stud 20 and the substrate 30 to protect the contact area from oxidation by oxygen from the surrounding area during the welding operation. To control the flow of gas to the contact area, the gas reservoir 70, the gas supply line 71, the welding unit 50, the gas hose 72 or the welding gun 40 include valves (not shown), in particular controllable valves.

[0016] The welding unit 50 comprises an input device 51 with an actuation element 52 and an output device 53 with a visual display element 54 and a wireless transmission unit. The input device 51 serves to input the parameters of the welding method to be performed with the welding device 10 by a user of the welding device 10, such as, for example, the voltage, the current strength, the power and duration of the welding current, the position and the speed of the stud, etc. The output device 53 serves to output information to the user, for example information on the parameters of the welding method, information on the detected emissions or other variables of the welding method, information on the quality of the welding operation, information on measures to improve the welding operation, information on the detected properties of the welding studs or information derived from the aforementioned variables and / or recommendations or instructions regarding the cleaning and / or maintenance of the welding device 10, in particular the welding gun 40.

[0017] A communication line 65 serves for communication between the welding gun 40, in particular a control device of the welding gun 40, not shown in Fig. 1, and the welding unit 50, in particular the control unit and / or the input device 51 and / or the output device 53. By means of this communication, for example, an exchange of information regarding the parameters of the welding operation is achieved, for example in order to achieve or to make it easier to synchronize the welding current with the movement of the welding stud 20. In a not shown embodiment, the communication between the welding gun and the welding unit is performed wirelessly, by wireless communication or by means of a first electric cable carrying the welding current.

[0018] The welding gun 40 has a housing 42 with an opening 46, from which a handle 43 with a trigger switch 41 projects. The welding gun 40 also has a stud holder 44 in which the welding stud 20 is held during the welding operation. For this purpose, the stud holder comprises, for example, two, three, four or more resilient arms (not shown in detail), between which the welding stud 20 is inserted and held by a clamping engagement. For applying the welding current to the welding stud 20, the welding gun 40 also has a welding current contact element, which is integrated in the stud holder 44, for example in the form of one or more resilient arms.

[0019] The welding gun 40 also has a control device 99 for controlling the various components and devices of the welding gun and the welding unit 50. The control device 99 is intended to control one or more parameters of the welding operation. To this end, the control device 99 includes various electronic components, such as one or more microprocessors, one or more temporary or permanent data memories, etc.

[0020] The welding gun 40 also has a stud lift device which is formed as a first lift magnet which, when activated, exerts a force on the stud holder 44 in a rearward (upward in FIG. 1 ) direction away from the opening 46. A control device 99 communicates with the stud lift device via signal lines (not shown) to control it, in particular to activate and deactivate it.

[0021] The welding gun 40 also has a stud immersion device formed as a spring element or a second lift magnet, which when activated exerts a force on the stud holder 44 forward (downward in FIG. 1 ) towards the opening 46. The control device 99 communicates with the stud immersion device via signal lines (not shown) to control it, in particular to activate and deactivate it. If the stud immersion device is formed as a spring element, this spring element is preferably tensioned when the stud holder is moved backwards by the stud lift device, so that the spring element moves the stud holder forward as soon as the stud lift device is stopped.

[0022] In a welding method using the welding device 10, the substrate 30 and the stud 20 are first provided. In a further step, information regarding, for example, desired parameters of the subsequent welding operation are input by a user via an input device. In a further step, a welding current between the welding stud 20 and the substrate 30 is applied to the welding stud 20 by the welding unit 50 using the first cable 61 and the second cable 62. In a further step, the welding stud 20 is lifted away from the substrate by a stud lift device while maintaining the welding current flowing between the welding stud 20 and the substrate 30, forming an arc between the welding stud 20 and the substrate 30. Due in particular to the heat generated by the arc, the material of the welding stud 20 and / or the substrate 30 is then partially liquefied. In a further step, the welding stud 20 is immersed in the liquefied material of the welding stud 20 or the substrate 30 by a stud immersion device. The liquefied material of the welding stud 20 or the substrate 30 then solidifies such that the welding stud 20 is connected to the substrate 30 in an integrally joined state.

[0023] 2 shows diagrammatically a longitudinal section of a welding device 100 intended to weld a welding stud 120 along a welding axis 105 in a welding direction 110 to a substrate 130. The welding device 100 is formed as a welding gun defining the welding direction 110. The welding device 100 has a holding device 144 formed as a stud holder with an outer diameter dA, which has a stud receptacle 121 with an inner diameter dI for holding the welding stud 120 during the welding operation, into which the welding stud 120 can be inserted and is preferably held with a clamping effect. A contact surface 125 of the welding stud 120 comes into contact with the substrate 130 before and / or during the welding operation.

[0024] The welding device 100 comprises a housing 101, shown diagrammatically, with a handle (not shown) and a trigger switch (not shown), as well as an inert gas cover 140, which is intended to be filled with inert gas in order to suppress or completely prevent oxidation of the weld melt by oxygen from the surrounding air. For this purpose, the inert gas cover 140 has an inert gas supply comprising a plurality of first connecting channels 150 arranged in the form of rings around the welding axis 105. An inert gas hose 145 or the like for supplying the inert gas cover 140 can be connected to the inert gas supply. Each of the first connecting channels 150, which extend axially relative to the welding axis 105, opens into the main chamber 141 of the inert gas cover 140 with an inlet opening 160, which is likewise arranged in the form of a ring around the welding axis 105 and together forms an inert gas inlet. In a not shown embodiment, the inert gas inlet comprises a single inlet opening in the form of a ring surrounding the welding axis. Furthermore, the inert gas cover 140 has a plurality of outlet openings 170, which are likewise arranged in the form of a ring around the welding axis and which open outwardly through the inert gas cover 140 in a radial direction relative to the welding axis 105 into a peripheral region and form inert gas outlets. The outlet openings 170 are each arranged transversely to the welding axis 105 (perpendicular to the plane of the drawing in FIG. 2), in particular offset circumferentially from the inlet openings 160.

[0025] Additionally, the inert gas cover 140 has an opening 180. The opening 180 faces the welding direction 110 and has an opening diameter dM in a direction transverse to the welding direction 110. An inert gas inlet, specifically the inlet opening 160, is at an inlet distance aE from the opening 180 on the side opposite the welding direction 110. An inert gas outlet, specifically the outlet opening 170, is at an outlet distance aA from the opening 180 on the side opposite the welding direction 110.

[0026] The exit distance aA is approximately half the size of the difference between the opening diameter dM and the inner diameter dI, i.e., approximately the same size as the radial distance x between the weld stud 120 and the inert gas cover 140. Moreover, the exit distance aA is greater than the inlet distance aE. When the opening 180 is covered by the substrate 130, the inert gas flowing into the main chamber 141 through the inlet opening 160 flows along the flow path 190 first to the area radially outside the opening 180, then radially inward from all sides to the weld stud 120, and then substantially axially upward to the exit opening 170. This causes the formation of a toroidal flow pattern that is radially symmetrically arranged around the weld axis 105 and has the effect of uniformly and effectively filling the weld point of the weld stud 120 with inert gas. For example, the ambient air that only slowly exits the narrow gap between the holding device 144 and the inert gas cover (above the exit opening 170 in FIG. 2) is entrained in the flow through the exit opening 170 and does not approach the weld point.

[0027] FIG. 3 shows a schematic longitudinal section of a welding device 200 substantially identical to the welding device 100 (FIG. 2). Identical elements have identical reference numerals. The welding device 200 differs from the welding device 100 in particular in the arrangement of the inlet openings 160 and the outlet openings 170. The outlet distance aA is approximately half the size of the difference between the opening diameter dM and the outer diameter dA, i.e. approximately the same as the radial distance y between the holding device 144 and the inert gas cover 140. Furthermore, the outlet distance aA is smaller than the inlet distance aE, but is larger than half the size of the inlet distance aE. The outlet openings 170 are each arranged offset from the inlet openings 160 in the circumferential direction around the welding axis 105, such that the interaction between the inlet gas flowing in and the inert gas flowing out is reduced.

[0028] The invention has been described on the basis of the example of a welding gun, where the features of the described embodiments can also be combined with one another in a single fastening device if necessary, it being pointed out that the device according to the invention is also suitable for other purposes.

Claims

1. 1. A welding device which is a welding gun for welding a weld stud to a substrate (fastened member) along a welding axis in a welding direction, the welding device comprising: an inert gas cover having an inert gas inlet arranged in the form of a ring around the welding axis, an inert gas outlet, and an opening facing the welding direction, the opening having an opening diameter in a direction transverse to the welding direction, the inert gas inlet being at an entrance distance from the opening opposite the welding direction, and the inert gas outlet being at an exit distance from the opening opposite the welding direction, the welding device further comprising a holding device for holding the weld stud within the inert gas cover during a welding operation, the holding device having an outer diameter and a stud receiving portion having an inner diameter, the exit distance being at least half the difference between the opening diameter and the outer diameter and at least half the magnitude of the entrance distance.

2. 2. The welding device of claim 1, wherein the inert gas inlet is oriented on an area radially outward of the opening to generate a flow of inert gas along the opening in a radial direction relative to the weld axis when the opening is covered.

3. The welding device of claim 1 or 2, wherein the inert gas inlet comprises an inlet opening in the form of a ring surrounding the weld axis.

4. The welding device of any one of claims 1 to 3, wherein the inert gas inlet comprises a plurality of inlet openings arranged in the form of a ring around the welding axis.

5. The welding device according to any one of claims 1 to 4, wherein the inert gas outlet comprises a plurality of outlet openings arranged in the form of a ring around the welding axis.

6. The welding device of any one of claims 1 to 5, wherein the inert gas outlets lead outwardly through the inert gas cover in a radial direction relative to the welding axis to a surrounding area.

7. The welding device of any one of claims 1 to 6, wherein the inert gas outlet is offset from the inert gas inlet in a direction transverse to the welding axis.

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