Teaching tool for welding torch, welding torch equipped with such teaching tool, and method for teaching a welding path for a welding torch equipped with such teaching tool

Abstract

The present invention relates to a teaching tool (1) for a welding torch (10) having a gas nozzle (11) with an opening (12) for a non-molten electrode (13) having a tip (14), which is used when teaching a welding path (X) along a workpiece (W) of a welding torch (16) attached to a welding robot (16), in particular a plasma welding torch (15), the teaching tool (1) having a substantially annularly symmetric body portion (2) having a free end (3), a welding torch (10) provided with such a teaching tool (1), and a method for teaching a welding path (X) of a welding torch (10) provided with such a teaching tool (1), wherein the body portion (2) is formed of an elastic material. The teaching tool (1) is characterized in that the body portion (2) has a connector (4) arranged on the side opposite to the free end (3), and the connector (4) is formed by a frustum (5) for fixing without tools to the opening (12) of the gas nozzle (11) of the welding torch (10).

Description

[Technical Field]

[0001] The present invention relates to a teaching tool for a welding torch, particularly a plasma welding torch, equipped with a gas nozzle having an opening for a non-melting electrode having a tip, used when teaching a welding path along a workpiece of a welding torch attached to a welding robot, the teaching tool having a substantially circularly symmetrical body having a free end, the body being formed from an elastic material.

[0002] Furthermore, the invention relates to a welding torch for a non-melting electrode, in particular a plasma welding torch, which is provided with a gas nozzle having an opening for the non-melting electrode and which is provided with a device for attachment to a welding robot.

[0003] Finally, the present invention relates to a method for teaching a welding path for a welding torch attached to a welding robot, comprising the teaching tool described above. [Background technology]

[0004] In robot welding, especially for welding large workpieces, it is extremely difficult for an operator to teach welding because the view from the welding nozzle is completely blocked by the gas nozzle, making it impossible to determine whether the welding electrode is facing the weld joint or arc position, and whether the distance between the nozzle and the workpiece is appropriate.

[0005] The present invention relates primarily to, but is not limited to, plasma welding in which an arc is formed between a non-melting electrode and a workpiece. Plasma welding torches are relatively large, which means that the view of the plasma gas nozzle during the teaching process is particularly limited or blocked, making the teaching process very difficult. If the view of the welding torch is obstructed or blocked during the teaching process, it is impossible to determine whether the electrode is pointed at the desired position on the welding trajectory and whether the distance between the electrode or gas nozzle and the workpiece is appropriate.

[0006] If the teaching process is carried out using a normal welding torch with a non-melting electrode, there is also a risk of damaging the workpiece or parts of the welding torch, the gas nozzle or the electrode, etc.

[0007] Special welding torches for use in the teaching process are known from the prior art. For example, JPH0726061U describes a dummy contact tip that can be connected to a welding torch via a screw. The dummy contact tip is made of an elastic material and its dimensions correspond to those of the actual electrode.

[0008] CN207952899U describes a teaching tool for a welding torch according to the state of the art, but the connection with the welding torch or welding robot is not described in detail.

[0009] CN205497532U discloses another teaching tool for industrial robots.

[0010] Another teaching tool for a welding robot for MIG / MAG welding processes is shown in JPH0726062U. The teaching tool is removably screwed onto the torch and includes a compression spring or a rubber leaf spring. Summary of the Invention [Problem to be solved by the invention]

[0011] Known elements of this type for use in the teaching process of a welding torch often have a complex design or are complicated to attach and detach from the welding torch. [Means for solving the problem]

[0012] It is therefore an object of the present invention to create a teaching tool for a welding torch with a non-melting electrode, in particular a plasma welding torch, that can be particularly easily and quickly attached to and detached from the welding torch and that has a particularly simple and cost-effective design.A further object of the present invention is to provide a welding torch with a non-consumable electrode, in particular a plasma welding torch, and a method for teaching a welding path for welding with such a welding torch, whereby the teach-in operation can be performed simply and safely and without risk of damaging the workpiece or parts of the welding torch.The disadvantages of known devices and methods are avoided or at least reduced.

[0013] The object of the present invention is solved, on the one hand, by the aforementioned teaching tool, in which the body has a connector arranged opposite the free end, the connector formed by a truncated cone for tool-free fixation in the opening of the gas nozzle of a welding torch. The teaching tool is made of an elastic material, which, on the one hand, prevents damage to the workpiece during the teaching process. On the other hand, the teaching tool can be attached to the welding torch in this way and can be particularly quickly and easily removed. The elastic material and corresponding dimensions of the teaching tool allow the teaching tool to be held in the gas nozzle by friction, and no fastening elements or tools are required for assembly and disassembly. The connector of the teaching tool is formed by a truncated cone. This design makes it easy to position the teaching tool in the opening of the gas nozzle of the welding torch and hold the teaching tool by friction. The non-melting electrode of the welding torch does not need to be removed during the changeover for the teaching process, but only needs to be moved into the gas nozzle so that space for the teaching tool is created in the gas nozzle opening. This teaching is also particularly simple and therefore inexpensive to manufacture.

[0014] Preferably, the average diameter of the cone connector is slightly larger than the diameter of the gas nozzle opening of the welding torch. This dimensioning ensures that the teaching tool is firmly held in the gas nozzle opening by friction. Preferably, the average diameter of the cone connector is 4% to 8% larger than the diameter of the gas nozzle opening of the welding torch.

[0015] If a flange with a larger diameter than the connector is placed between the connector and the free end of the teaching tool's body, it can ensure that the teaching tool is attached to the gas nozzle in the desired position. On the one hand, the flange prevents the teaching tool from tilting relative to the gas nozzle, and on the other hand, the specified distance of the teaching tool's tip from the end of the gas nozzle is always ensured. This ensures the correct tool center point (TCP) during the teaching process.

[0016] In particular, the body of the teaching tool is made in one piece, which makes it possible to produce the teaching tool very easily and cost-effectively.

[0017] When the elastic material of the teaching tool body contains graphitic carbon, especially 30 to 40 volume percent, it can improve the material's wear resistance and therefore extend its service life. For teaching tools made of ordinary silicone rubber, the wear resistance drops significantly after four uses. Adding some graphitic carbon to the silicone rubber matrix can increase the teaching tool's service life by more than 10 times. Graphitic carbon can be mixed into the silicone rubber matrix in the form of powder and / or a powder composite.

[0018] Advantageously, the elastic material of the body has a Shore hardness of 40 to 50 Shore A, in particular 45 to 48 Shore A. Such a hardness value is advantageous for application of the teaching tool and for holding it at the opening of the gas nozzle.

[0019] According to another feature of the invention, the elastic material of the body has an elastic modulus of 7.8 to 12 MPa, in particular 9.8 to 10 MPa.

[0020] A suitable material for the teaching tool body is rubber or a rubber compound, especially silicone rubber. Materials with these aforementioned characteristics are used to adjust friction, hardness, abrasion resistance, and elasticity. Silicone rubber exhibits ideal elasticity and heat resistance, even at temperatures above 150°C. Furthermore, silicone rubber has a Shore hardness of 10 to 80 and an elastic modulus of 8 MPa when its elastic hardness is 40 Shore A. Therefore, even a small elastic deformation can generate a sufficient pushing force to achieve friction between the teaching tool and the metal surface of the gas nozzle. Friction force is calculated as f = μ * N, where f is the friction, μ is the friction coefficient (0.25 between copper and silicone rubber), and N is the normal force. As a result, friction f is proportional to the normal force N and the elastic deformation. In this case, a deformation of 0.2 to 0.4 mm of silicone rubber is sufficient to generate friction f to overcome gravity.

[0021] If fluorescent particles are mixed into the elastic material or the body is at least partially surrounded by a fluorescent top or cover layer, the visibility of the teaching tool during the teaching process can be enhanced. A fluorescent teaching tool can be advantageous for an operator, especially in a dark working environment.

[0022] According to another feature of the invention, the free end of the body of the teaching tool is rounded, in particular with a diameter of 0.4-0.6 mm, which has proven to be suitable in practice for the wear resistance of the tip.

[0023] The object of the present invention is also achieved by a welding torch for a non-melting electrode, in particular a plasma welding torch, which comprises a gas nozzle having an opening for a non-melting electrode and a device for mounting on the welding robot as described above, whereby the teaching tool as described above is provided and fixed to the opening of the gas nozzle. For the advantages achievable thereby, see the above description of the teaching tool.

[0024] Finally, the object of the present invention is also solved by the above-mentioned method for teaching a welding path of a welding torch attached to a welding robot equipped with the above-mentioned teaching tool, wherein a desired welding path is traversed using the welding torch to which the teaching tool is fixed. For advantages that can be achieved by this method, please refer to the explanation of the teaching method.

[0025] Advantageously, contact of the teaching tool with the workpiece is detected and the teaching of the welding path is modified accordingly.

[0026] Contact of the teaching tool with the workpiece can be detected via a force detected at the welding robot or via an electrical voltage measurement at the teaching tool. The force acting on the teaching tool can be detected, for example, via a force measuring device typically present on the robot. In the latter case, a certain electrical conductivity is required for the teaching tool, which can be achieved, for example, by adding conductive particles (e.g., graphite, nickel-clad copper powder, and / or silver powder) to the elastic material of the teaching tool's body or by encasing the teaching tool's body in a conductive material. In a further embodiment, the body is at least partially surrounded by a conductive cover layer. The conductive cover layer can be applied by brushing, spraying, dipping, or other coating methods.

[0027] The present invention will now be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 shows a simplified diagram of a plasma welding torch that can be attached to a welding robot according to the prior art. [Figure 2] FIG. 2 shows a first embodiment of the teaching tool in detail. [Figure 3] FIG. 3 shows a second embodiment of the teaching tool. [Figure 4] FIG. 4 shows another teaching tool, which does not fall within the scope of protection of the present invention, with a cylindrical connector and a rounded free end. [Figure 5] FIG. 5 shows another embodiment of a teaching tool with a fluorescent top layer. [Figure 6] FIG. 6 shows a cross-sectional view of another embodiment of a teaching tool. [Figure 7] FIG. 7 shows a cross-sectional view of another embodiment of a teaching tool. [Figure 8] FIG. 8 shows a partial cross-sectional view of a gas nozzle equipped with a teaching tool according to the present invention according to the second embodiment as shown in FIG. [Figure 9] FIG. 9 shows a partial cross-sectional view of another gas nozzle with a teaching tool according to the present invention according to the second embodiment as shown in FIG. [Figure 10] FIG. 10 shows a partial cross-sectional view of another gas nozzle equipped with a teaching tool according to the present invention according to the embodiment shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 shows a simplified diagram of a welding torch 10, specifically a plasma welding torch 15, with a device 17 for mounting on a welding robot 16 (not shown) according to the prior art. The plasma welding torch 15 includes a gas nozzle 11 with an opening 12 and a non-melting electrode 13, typically made of tungsten. Depending on the design of the welding torch, the non-melting electrode 13 may or may not protrude. Various electrical cables and cooling lines (not shown) are supplied to the plasma welding torch 15 via a hose package S. In the diagram above, the plasma welding torch 15 is supplied with filler metal Z at a welding point P, which is used to weld a workpiece W along a welding path X. Before the welding process is performed, a so-called teaching process is typically performed, during which the movements of the welding robot 16 are determined so that the subsequent welding process is performed along the desired welding path X. If the distance between the plasma welding torch 15 and the workpiece W during the teaching process is selected to be too small, there is a risk of damaging the workpiece W or components of the plasma welding torch 15, especially the non-melting electrode 13. This problem is eliminated by the present invention.

[0030] FIG. 2 shows in detail a first embodiment of the teaching tool 1. The teaching tool 1 has a substantially annularly symmetrical body 2 having a free end 3, the body 2 being formed of an elastic material, such as rubber or a rubber compound, in particular silicone rubber. Furthermore, the body 2 of the teaching tool 1 has a connector 4 arranged opposite the free end 3, the connector 4 being designed to be fastened without tools to the opening 12 of the gas nozzle 11 of the welding torch 10 (see FIG. 1). The connector 4 of the body 2 is formed by a truncated cone 5, which facilitates fastening the teaching tool 1 within the opening 12 of the gas nozzle 11 (see FIG. 8). The average diameter D of the connector 4 (see FIG. 3) is 1 / 2 mm. A is the diameter D of the opening 12 of the gas nozzle 11 of the welding torch 10 so that the teaching tool 1 is held only by friction within the gas nozzle 11 (see FIG. 8). G Slightly larger than

[0031] FIG. 3 shows a second embodiment of the teaching tool 1, in which the maximum diameter D M Larger diameter D F A flange 6 having a groove 1111 is disposed between the connector 4 and the free end 3 of the main body 2. The flange 6, which is a kind of restriction for the teaching tool 1, ensures that the teaching tool 1 is attached to the gas nozzle 11 at a desired position. The flange 6 prevents the teaching tool 1 from tilting relative to the gas nozzle 11, and the specified distance between the end of the gas nozzle 11 and the tip of the teaching tool 1 is always ensured.

[0032] FIG. 4 shows the diameter D of the opening 12 of the gas nozzle 11. G The outer diameter D is slightly larger than the A 1 shows another embodiment of the teaching tool 1 with a cylindrical connector 4 having a diameter of 0.4 to 0.6 mm. This cylindrical connector 4 does not fall within the scope of protection of the present invention. The tip of the free end 3 of the main body 2 presents a radius 8, in particular a radius 8 having a diameter of 0.4 to 0.6 mm.

[0033] Figure 5 shows another embodiment of the teaching tool 1, which in all other respects corresponds to the embodiment according to Figure 3. The connector 4 is formed by a truncated cone 5, the mean diameter of which is D C is the diameter D of the opening 12 of the gas nozzle 11 G In this embodiment, the body 2 of the teaching tool 1 is at least partially surrounded by a fluorescent top layer 7. The fluorescent top layer 7 can be applied by brushing, spraying, dipping, or other coating methods. Instead of the fluorescent top layer 7, fluorescent particles can also be mixed into the elastic material of the body 2 of the teaching tool 1. The fluorescent top layer 7 can improve the visibility of the teaching tool 1 during the teaching process.

[0034] Figure 6 shows a cross-sectional view of another embodiment of a teaching tool 1 similar to the embodiment according to Figure 3. The only difference is that there is a recess 18 in the connector 4 opposite the free end 3 of the body 2 of the teaching tool 1, in which the tip of the non-meltable electrode 13 of the welding torch 10 can be placed during the teaching process (see Figure 10). The recess 18 is configured to correspond to the shape of the tip of the non-meltable electrode 13.

[0035] FIG. 7 shows a cross-sectional view of another embodiment of the teaching tool 1. The angle of the recess 18 is smaller than that of the recess 18 according to FIG. 6. If the elastic material of the body 2 of the teaching tool 1 contains graphitic carbon C, on the one hand, the wear resistance and thus the service life of the teaching tool 1 can be improved. On the other hand, the addition of this or other conductive particles (such as nickel-clad copper powder or silver powder) can make the teaching tool 1 conductive. This means that contact between the welding torch 10 or teaching tool 1 and the workpiece W can be detected by short-circuit detection. For this purpose, the measurement voltage U M is applied to the teaching tool 1 via a gas nozzle 11 and is detected via a voltage drop when the free end 3 of the teaching tool 1 contacts the conductive workpiece W. When contact occurs, an acoustic and / or visual signal can be emitted.

[0036] 8 shows a partial cross-sectional view of a gas nozzle 11 equipped with a teaching tool 1 according to the second embodiment of the present invention shown in FIG. G The non-meltable electrode 13 can remain in the gas nozzle 11 during the teaching process and is simply moved backward. This facilitates handling during the teaching process. The maximum diameter D of the connector 4 M is the diameter D of the opening 12 of the gas nozzle 11. GThe slightly larger teaching tool 1 is inserted into the opening 12 of the gas nozzle 11. Due to the elastic material of the body 2 of the teaching tool 1, the teaching tool 1 can be easily inserted into the opening 12 and it is held in place by friction. The flange 6 prevents the teaching tool 1 from tilting relative to the gas nozzle 11 and ensures that the distance between the end of the gas nozzle 11 and the tip at the free end 3 of the teaching tool 1 is correct.

[0037] 9 shows a partial cross-sectional view of another gas nozzle 11 equipped with a teaching tool 1 according to the present invention according to the second embodiment as shown in FIG. 3. Arrows G indicate the path of the inert gas G in the gas nozzle 11 during the welding process.

[0038] Finally, Figure 10 shows a partial cross-sectional view of another gas nozzle 11 equipped with a teaching tool 1 according to the present invention according to the embodiment shown in Figure 7. Here, the tip of the non-meltable electrode 13 can be placed in the recess 18 of the connector 4 of the teaching tool 1 during the teaching procedure.

[0039] Using the described teaching tool 1, the teaching process can be improved and the risk of breaking the workpiece W or components of the welding torch 10 can be minimized or prevented.

Claims

1. A teaching tool (1) for a welding torch (10), particularly a plasma welding torch (15), including a gas nozzle (11) having an opening (12) for a non-melting electrode (13) having a tip (14), used when teaching a welding path (X) along a workpiece (W) of a welding torch (10) attached to a welding robot (16), the teaching tool (1) having a substantially circularly symmetrical body (2) having a free end (3), the body (2) being formed of an elastic material, the teaching tool (1) characterized in that the body (2) has a connector (4) arranged on the opposite side of the free end (3), the connector (4) being formed by a truncated cone (5) for tool-less fixation to the opening (12) of the gas nozzle (11) of the welding torch (10).

2. The average diameter of the truncated cone (5) (D Ｃ ) is the diameter (D) of the opening (12) of the gas nozzle (11) of the welding torch (10). Ｇ 2. A teaching tool (1) according to claim 1, characterized in that it is slightly larger than the .

3. The average diameter of the truncated cone (5) (D Ｃ ) is the diameter (D) of the opening (12) of the gas nozzle (11) of the welding torch (10). Ｇ 3. A teaching tool (1) according to claim 2, characterized in that it is 4 to 8% larger than the

4. Connector (4) has a larger diameter (D Ｆ 2. The teaching tool (1) according to claim 1, characterized in that a flange (6) having a flange (6) is arranged between the connector (4) and the free end (3) of the body part (2).

5. 2. A teaching tool (1) according to claim 1, characterized in that the body (2) is made in one piece.

6. 2. A teaching tool (1) according to claim 1, characterized in that the elastic material of the body (2) contains graphitic carbon (C), in particular 30 to 40 volume percent.

7. 2. A teaching tool (1) according to claim 1, characterized in that the body (2) is made of rubber or a rubber compound, in particular silicone rubber.

8. 2. A teaching tool (1) according to claim 1, characterized in that fluorescent particles are mixed into the elastic material or the body (2) is at least partly surrounded by a fluorescent top layer (7).

9. 2. Teaching tool (1) according to claim 1, characterized in that the free end (3) of the body (2) has a radius (8), in particular with a diameter of 0.4 to 0.6 mm.

10. A welding torch (10), in particular a plasma welding torch (15), for a non-melting electrode (13), comprising a gas nozzle (11) having an opening (12) for the non-melting electrode (13) and comprising a device (17) for attachment to a welding robot (16), characterized in that the teaching tool (1) according to any one of claims 1 to 9 is provided and fixed to the opening (12) of the gas nozzle (11).

11. 10. A method for teaching a welding path (X) of a welding torch (10) equipped with a teaching tool (1) and attached to a welding robot (16), characterized in that the desired welding path (X) is traversed using the welding torch (10) to which the teaching tool (1) according to any one of claims 1 to 9 is fixed.

12. 12. The method according to claim 11, characterized in that the contact of the teaching tool (1) with the workpiece (W) is detected and the teaching of the welding path (X) is corrected accordingly.

13. 12. The method according to claim 11, characterized in that the contact of the teaching tool (1) with the workpiece (W) is detected via a force (F) detected at the welding robot (16).

14. The contact of the teaching tool (1) with the workpiece (W) generates an electrical measurement voltage (U Ｍ 13. The method of claim 12, wherein the detection is via

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