Teaching tool for a welding torch, welding torch equipped with such a teaching tool, and method for teaching a welding path of a welding torch equipped with such a 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 welding torch provided with a gas nozzle having an opening for a non-molten electrode, which is used when teaching a welding path along a workpiece of a welding torch attached to a welding robot, in particular, a teaching tool for a plasma welding torch, which has a substantially annularly symmetric body portion having a free end, and the body portion is formed of an elastic material.

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

[0003] Finally, the present invention relates to a method for teaching a welding path of a welding torch attached to a welding robot, which is provided with the aforementioned teaching tool.

Background Art

[0004] In robot welding, particularly in robot welding 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. As a result, it is impossible to determine whether the welding electrode is facing the weld joint or the arc position, or whether the distance between the nozzle and the workpiece is appropriate.

[0005] The present invention mainly relates to plasma welding in which an arc is formed between a non-molten electrode and a workpiece, but is not limited thereto. Plasma welding torches are relatively large, and therefore, the view of the plasma gas nozzle during the teaching process is particularly restricted or blocked, making the teaching process very difficult. When the view of the welding torch is obstructed or blocked during the teaching process, it is impossible to determine whether the electrode is directed to the desired position on the welding track, or whether the distance between the electrode or the gas nozzle and the workpiece is appropriate.

[0006] When the teaching process is performed using a normal welding torch equipped with a non-fused electrode, there is also a risk of damaging the workpiece or parts of the welding torch, such as the gas nozzle or the electrode.

[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 the welding torch via a screw. The dummy contact tip is formed 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 to the welding torch or the welding robot is not described in detail.

[0009] CN205497532U discloses another teaching tool for an industrial robot.

[0010] Another teaching tool for a welding robot for the MIG / MAG welding process is shown in JPH0726062U. The teaching tool is removably screwed to the torch and includes a compression spring or a rubber plate spring.

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

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

[0013] The object of the present invention is, on the one hand, solved by the teaching tool described above. The body part has a connector arranged on the side opposite to the free end. The connector is formed by a frustum of a cone for fixing without tools to the opening of the gas nozzle of the welding torch. The teaching tool is made of an elastic material, which, on the one hand, can prevent damage to the workpiece during the teaching process. On the other hand, the teaching tool is thus attached to the welding torch and can be removed particularly quickly and easily. The elastic material of the teaching tool and its corresponding dimensions enable the teaching tool to be held in the gas nozzle by friction, and a fastening element and tools are not required for assembly and disassembly. The connector of the teaching tool is formed by a frustum of a cone. This design facilitates placing the teaching tool at the opening of the gas nozzle of the welding torch and holding the teaching tool by friction. The non-consumable electrode of the welding torch does not need to be removed during the change for the teaching process, but only needs to be moved within the gas nozzle so that a space for the teaching tool is created at the opening of the gas nozzle. This teaching is also particularly simple and thus not costly to manufacture.

[0014] Preferably, the average diameter of the frustum-shaped connector is slightly larger than the diameter of the opening of the gas nozzle of the welding torch. Such a dimension setting ensures that the teaching tool is firmly held in the opening of the gas nozzle by friction. Preferably, the average diameter of the frustum is 4% to 8% larger than the diameter of the opening of the gas nozzle of the welding torch.

[0015] When a flange having a diameter larger than the connector is disposed between the connector and the free end of the main body of the teaching tool, it is possible to ensure that the teaching tool is attached to the gas nozzle at a desired position. On the one hand, the flange prevents the teaching tool from tilting with respect to the gas nozzle, and on the other hand, a defined distance from the end of the gas nozzle to the tip of the teaching tool is always ensured. This guarantees an appropriate tool center point (TCP) during the teaching process.

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

[0017] When the elastic material of the main body of the teaching tool contains graphitic carbon, particularly 30 to 40 volume percent, the wear resistance of the material can be improved, and thus the service life can be extended. In the case of a teaching tool made of a general silicone rubber, the wear resistance significantly decreases after 4 uses. Adding some graphitic carbon to the silicone rubber matrix improves the life of the teaching tool by more than 10 times. The graphitic carbon can be mixed into the silicone rubber matrix in the form of powder and / or powder composite material.

[0018] Advantageously, the elastic material of the main body has a Shore hardness of 40 to 50 Shore A, particularly 45 to 48 Shore A. Such hardness values are advantageous for the application of the teaching tool and for holding at the opening of the gas nozzle.

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

[0020] Materials suitable for the main body of the teaching tool are rubber or rubber compounds, particularly silicone rubber. Materials having the above-described characteristics are used to adjust friction, hardness, wear resistance, and elasticity. Silicone rubber exhibits ideal performance in terms of elasticity and heat resistance even at temperatures above 150°C. Furthermore, since silicone rubber has a Shore hardness of about 10 to 80 and an elastic modulus of 8 MPa when the elastic hardness is 40 Shore A, a slight elastic deformation can generate a sufficient extrusion force to obtain the friction between the teaching tool and the metal surface of the gas nozzle. The frictional force is calculated by f = μ * N, where f is friction, μ is the coefficient of friction (0.25 between copper and silicone rubber), and N is the normal force. As a result, the friction f is proportional to the normal force N and the elastic deformation. In this case, a deformation of 0.2 mm to 0.4 mm of the silicone rubber is sufficient to generate a frictional force f that overcomes gravity.

[0021] When fluorescent particles are mixed into the elastic material or the main 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. The fluorescent teaching tool can be advantageous for the operator, particularly in a particularly dark working environment.

[0022] According to another feature of the present invention, the free end of the main body of the teaching tool has a rounded shape, particularly a rounded shape having a diameter of 0.4 to 0.6 mm. Such a radius has been proven to be actually suitable with respect to the wear resistance of the tip.

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

[0024] Finally, the object of the present invention is also achieved by the above-described method for teaching the welding path of a welding torch attached to a welding robot equipped with the above-described teaching tool, wherein the desired welding path is solved by the method of traversing with the welding torch to which the teaching tool is fixed. For the advantages achievable by this method, reference is made to the above description of the teaching.

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

[0026] Contact of the teaching tool with the workpiece can be detected via the force detected in the welding robot or via the electrical measurement voltage in the teaching tool. The force acting on the teaching tool can be detected, for example, via a force measuring device normally present in 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 main body of the teaching tool or by wrapping the main body of the teaching tool with a conductive material. In a further embodiment, the main 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 be described in more detail with reference to the accompanying drawings.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying out the Invention

[0029] Figure 1 schematically shows a welding torch 10, in particular a plasma welding torch 15, with a device 17 for attachment to a welding robot 16 (not shown) according to the prior art. The plasma welding torch 15 includes a gas nozzle 11 having an opening 12 and a non-consumable electrode 13 typically made of tungsten. Based on the design of the welding torch, the non-consumable electrode 13 can or cannot protrude. Various electrical cables and cooling lines (not shown) are supplied to the plasma welding torch 15 via a hose package S. In the upper figure, the plasma welding torch 15 is supplied with a filler Z at the welding point P, and using the welding point, the workpiece W is welded along the welding path X. Before the welding process is performed, a so-called teaching process is usually carried out. In the teaching process, the movement of the welding robot 16 is determined so that the subsequent welding process is performed along the desired welding path X. If, during the teaching process, the distance between the plasma welding torch 15 and the workpiece W is selected to be too small, there is a risk of damage to the workpiece W or components of the plasma welding torch 15, in particular the non-consumable electrode 13. This problem is eliminated by the present invention.

[0030] Figure 2 shows in detail a first embodiment of the teaching tool 1. The teaching tool 1 has a substantially annularly symmetric body part 2 with a free end 3, and the body part 2 is formed of an elastic material, such as rubber or a rubber compound, in particular silicone rubber. Further, the body part 2 of the teaching tool 1 has a connector 4 arranged on the opposite side of the free end 3, and the connector 4 is designed to be fixed 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 part 2 is formed by a frustum of a cone 5 to facilitate fixing the teaching tool 1 within the opening 12 of the gas nozzle 11 (see FIG. 8). The average diameter D A of the connector 4 (see FIG. 3) is slightly larger than the diameter D G of the opening 12 of the gas nozzle 11 of the welding torch 10 such that the teaching tool 1 is held only by friction within the gas nozzle 11 (see FIG. 8).

[0031] Figure 3 shows a second embodiment of the teaching tool 1, with the maximum diameter D of the connector 4 M A flange 6 having a larger diameter D F is disposed between the connector 4 and the free end 3 of the main body 2. The flange 6, which is a kind of limitation of the teaching tool 1, can ensure 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 with respect to the gas nozzle 11, and a defined distance from the end of the gas nozzle 11 to the tip of the teaching tool 1 is always ensured.

[0032] Figure 4 shows another embodiment of the teaching tool 1 with a cylindrical connector 4 having an outer diameter D that is slightly, preferably 4% - 8% larger than the diameter D G of the opening 12 of the gas nozzle 11. 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 shows a rounding 8, particularly a rounding 8 having a diameter of 0.4 - 0.6 mm. A Figure 5 shows another embodiment of the teaching tool 1, which corresponds to the embodiment according to Figure 3 in all other respects. The connector 4 is formed by a frustum of a cone 5, and the average diameter D

[0033] of the frustum of the cone is slightly larger than the diameter D C of the opening 12 of the gas nozzle 11. G In this embodiment, the main 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 main 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 the teaching tool 1 similar to the embodiment according to FIG. 3. The only difference is that there is a recess 18 in the connector 4 on the opposite side of the free end 3 of the main body 2 of the teaching tool 1, and the tip of the non-melting electrode 13 of the welding torch 10 can be arranged in the recess 18 during the teaching process (see FIG. 10). The recess 18 is configured to correspond to the shape of the tip of the non-melting electrode 13.

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

[0036] Figure 8 shows a partial cross-sectional view of the gas nozzle 11 provided with the teaching tool 1 according to the second embodiment shown in FIG. 3. The gas nozzle 11 has an opening 12 having a diameter D G . The non-melting electrode 13 can stay within the gas nozzle 11 during the teaching process and is simply moved backward. This facilitates handling during the teaching process. The maximum diameter D M of the connector 4 is the diameter D G of the opening 12 of the gas nozzle 11The slightly larger teaching tool 1 is inserted into the opening 12 of the gas nozzle 11. Due to the elastic material of the main body 2 of the teaching tool 1, the teaching tool 1 can be easily inserted into the opening 12, and it is held due to friction. The flange 6 prevents the teaching tool 1 from tilting with respect 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] FIG. 9 shows a partial cross-sectional view of another gas nozzle 11 provided with the teaching tool 1 according to the second embodiment of the present invention as shown in FIG. 3. The arrow G indicates the path of the inert gas G in the gas nozzle 11 during the welding process.

[0038] Finally, FIG. 10 shows a partial cross-sectional view of another gas nozzle 11 provided with the teaching tool 1 according to the present invention according to the above embodiment as shown in FIG. 7. Here, the tip of the non-consumable electrode 13 can be arranged 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 damage to the workpiece W or the components of the welding torch 10 can be minimized or prevented.

Claims

1. A teaching tool (1) for a welding torch (10) having a non-melting electrode (13) with a tip (14), which is used when teaching a welding path (X) along a workpiece (W) of the welding torch (10) attached to a welding robot (16). The teaching tool (1) has a substantially annularly symmetric body portion (2) with a free end (3). In the teaching tool (1), the body portion (2) is made of an elastic material. The body portion (2) has a connector (4) disposed on the side opposite to the free end (3). 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). The teaching tool (1) is characterized by this.

2. The average diameter (D Ｃ ) of the frustum (5) is slightly larger than the diameter (D Ｇ ) of the opening (12) of the gas nozzle (11) of the welding torch (10). The teaching tool (1) according to claim 1, characterized by this.

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

4. A flange (6) having a diameter (D Ｆ greater than that of the connector (4)) is disposed between the connector (4) and the free end (3) of the main body (2), the teaching tool (1) according to any one of claims 1 to 3, characterized in that.

5. The teaching tool (1) according to any one of claims 1 to 4, characterized in that the body portion (2) is made in one piece.

6. The teaching tool (1) according to any one of claims 1 to 5, characterized in that the elastic material of the body portion (2) contains graphite-like carbon (C), particularly 30 to 40 volume percent.

7. The teaching tool (1) according to any one of claims 1 to 6, characterized in that the body portion (2) is made of rubber or a rubber compound, particularly silicone rubber.

8. The teaching tool (1) according to any one of claims 1 to 7, characterized in that fluorescent particles are mixed into the elastic material, or the body portion (2) is at least partially surrounded by a fluorescent top layer (7).

9. The teaching tool (1) according to any one of claims 1 to 8, characterized in that the free end (3) of the body portion (2) has a diameter of particularly 0.4 to 0.6 mm and has a rounding (8).

10. A welding torch (10) for a non-melting electrode (13), particularly a plasma welding torch (15), comprising a gas nozzle (11) having an opening (12) for the non-melting electrode (13) and a device (17) for attaching to a welding robot (16). The welding torch (10) is 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. A method for teaching a welding path (X) of a welding torch (10) attached to a welding robot (16) and provided with a teaching tool (1), wherein 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. The method according to claim 11, characterized in that contact between the teaching tool (1) and the workpiece (W) is detected, and the teaching of the welding path (X) is corrected accordingly.

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

14. The contact between the machining tool (1) and the workpiece (W) is detected via the electrical measurement voltage (U Ｍ ) in the machining tool (1), the method according to claim 12 or 13, characterized in that.

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