Robot welding tongs state automatic detection method and transmission device

Abstract

This invention discloses an automatic detection method and transmission device for the state of a robot welding gun. The detection method includes determining a reference resistance value for the welding gun circuit and the current resistance value of the welding gun circuit after the electrode cap of the robot under test has been ground; comparing the reference resistance value and the current resistance value to determine whether the grinding of the electrode cap of the robot under test is qualified; setting a detection pressure for the welding gun pressing in, and establishing a standard welding gun pressing depth under the detection pressure; determining the pressing depth of the welding gun under test under the detection pressure; comparing the reference pressing depth and the pressing depth of the welding gun under test to determine the alignment of the welding gun electrode rod. This invention realizes automatic detection of the electrode cap grinding state and automatic detection of the welding gun alignment in a robot-based resistance spot welding system, providing a technical means for rapid and accurate detection of the welding gun state, thereby improving the welding quality of robot resistance spot welding.

Description

Technical Field

[0001] This invention relates to the field of robotic welding technology, and in particular to an automatic detection method and transmission device for the status of a robotic welding clamp. Background Technology

[0002] In robot-based resistance spot welding systems, the welding clamp's condition (diameter) significantly impacts welding quality. This condition includes the grinding quality of the electrode cap and the electrode alignment. The grinding quality of the electrode cap is typically inspected manually, which is time-consuming and offers limited controllability. For automated electrode cap inspection, current technologies use vision devices, increasing system cost, complexity, and stability. Existing technologies assess electrode alignment based on the appearance and dimensions of post-weld test pieces, a method of indirect verification requiring manual welding of test pieces and thus low accuracy. These issues urgently require solutions. Summary of the Invention

[0003] The purpose of this invention is to provide an automatic detection method and transmission device for the state of a robotic welding gun. By utilizing the dynamic resistance detection function of the welding controller and adopting the dynamic resistance detection method of the welding circuit, the state of electrode cap grinding is detected. The centering of the welding gun electrode rod is determined by the change in the pressing depth of the servo welding gun, thereby solving the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: an automatic detection method for the state of a robot welding gun, comprising:

[0005] Determine the reference resistance value of the welding clamp circuit, and the current resistance value of the welding clamp circuit after the electrode cap of the robot under test has been ground;

[0006] Compare the reference resistance value with the current resistance value, and determine whether the grinding of the electrode cap of the robot under test is qualified by comparing the comparison results;

[0007] Set the detection pressure for the welding clamp indentation, and establish a standard welding clamp indentation depth under the detection pressure. The standard welding clamp indentation depth is the average value of multiple welding clamp indentation depths under the condition of good welding clamp alignment.

[0008] Under test pressure, determine the depth of the welding clamp to be pressed in;

[0009] The centering of the welding clamp electrode rod is determined by comparing the reference indentation depth with the indentation depth of the welding clamp under test. The detection pressure includes a first detection pressure and a second detection pressure, with the second detection pressure being greater than the first detection pressure. The welding clamp indentation depth is the difference between the data of the welding clamp servo motor encoder under the first detection pressure and the data of the welding clamp servo motor encoder under the second detection pressure.

[0010] Furthermore, including:

[0011] Under the condition that the surface of the robot electrode cap is in good condition, the reference resistance curve of the welding clamp circuit is collected.

[0012] Determine the reference resistance value of the welding clamp circuit based on the reference resistance curve;

[0013] The electrode caps of the robot under test are ground and the current resistance curve of the welding clamp circuit is collected.

[0014] Determine the current resistance value of the welding clamp circuit based on the current resistance curve.

[0015] Furthermore, including:

[0016] After applying pressure to the welding clamp, the output voltage is measured, and the current and voltage of the circuit are detected.

[0017] Generate the loop resistance curve based on current and voltage;

[0018] The peak value reached again after the loop resistance curve drops is the welding clamp loop resistance value.

[0019] Furthermore, comparing the reference resistance value with the current resistance value and determining whether the grinding of the electrode cap of the robot under test is qualified based on the comparison result also includes:

[0020] Set the resistance limit threshold to Rz, the reference resistance value to R0, and the current resistance value to R1.

[0021] When R1-R0>Rz, the grinding of the electrode cap of the robot under test is deemed unqualified.

[0022] When R1-R0 < Rz, the electrode cap of the robot under test is deemed to have passed the grinding test.

[0023] Furthermore, setting the detection pressure for the welding clamp indentation, and establishing a standard welding clamp indentation depth under the detection pressure, also includes:

[0024] Set the number of pressurization cycles to n;

[0025] Under the first detection pressure, the welding clamp is pressed in n times, and the average value L1 of the welding clamp pressing depth is calculated.

[0026] Under the second detection pressure, the welding clamp is pressed in n times, and the average value L2 of the welding clamp pressing depth is calculated.

[0027] If the standard welding clamp penetration depth is set to A0, then A0 = L2 - L1.

[0028] Furthermore, assuming good alignment of the welding clamp, the first testing pressure is 500N, and the second testing pressure is the maximum permissible pressure.

[0029] Furthermore, by comparing the reference indentation depth with the indentation depth of the welding clamp under test, the alignment of the welding clamp electrode rod is determined, including:

[0030] Set the neutrality threshold Az, and set the indentation depth of the welding clamp to be tested to be A1;

[0031] When A1-A0>Az, the welding clamp is judged to have poor centering.

[0032] When A1-A0 < Az, the welding clamp is judged to be well aligned.

[0033] On the other hand, a robotic welding clamp transmission device is provided, comprising:

[0034] The robot itself;

[0035] A welding clamp, comprising a first electrode cap and a second electrode cap, the first electrode cap and the second electrode cap being disposed opposite to each other, the welding clamp being connected to the robot body;

[0036] A robot controller that controls the robot body to move the welding clamp axis of the welding clamp;

[0037] A welding transformer, which is mounted on the welding clamp and provides power to the welding clamp circuit;

[0038] A servo motor is connected to the welding clamp. The servo motor drives the welding clamp to move the first electrode cap by adjusting the pressing depth, thereby adjusting the relative position between the first electrode cap and the second electrode cap.

[0039] Furthermore, the robot body includes a mounting bracket, and the robot body is connected to the mounting bracket; the welding clamp includes a first electrode arm, a second electrode arm, and an electrode rod, the first electrode arm and the servo motor are respectively connected to the mounting bracket; the servo motor includes a transmission device, the transmission device is connected to the second electrode arm, the electrode rod is connected to the second electrode arm, the first electrode cap is connected to the electrode rod, and the second electrode cap is connected to the first electrode arm.

[0040] Furthermore, it also includes a welding controller, a current transformer, and a voltage detection circuit. The welding controller is connected to the welding transformer to provide it with power. The current transformer is installed on the welding clamp circuit, and the power detection circuit is connected to the electrode arm of the welding clamp.

[0041] Compared with the prior art, the beneficial effects of the present invention are: the present invention realizes the automatic detection of electrode cap grinding status and welding gun alignment of robot-based resistance spot welding system, providing technical means for rapid and accurate detection of welding gun status, thereby improving the welding quality of robot resistance spot welding. Attached Figure Description

[0042] Figure 1 This is a flowchart of the automatic detection method for the state of the robot welding gun in an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the robot welding clamp transmission device structure connection in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the welding controller, welding transformer, and electrical connection structure of the robot welding clamp transmission device in an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of the resistance curve in an embodiment of the present invention;

[0046] In the diagram: 10. Robot body; 20. Welding clamp; 30. Welding transformer; 40. Servo motor; 50. Welding controller; 60. Current transformer; 70. Power detection circuit; 11. Mounting bracket; 21. First electrode cap; 22. Second electrode cap; 23. First electrode arm; 24. Second electrode arm; 25. Electrode rod; 41. Transmission device; 42. Encoder. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] Please refer to the accompanying drawings in the specification. This invention provides a technical solution: such as... Figure 1 As shown, an automatic detection method for the status of a robot welding clamp includes the following steps:

[0051] S102. Determine the reference resistance value of the welding clamp circuit and the current resistance value of the welding clamp circuit after the electrode cap of the robot under test is ground.

[0052] Specifically, the welding clamp is pressurized and output voltage is applied, and the current and voltage of the circuit are detected; a circuit resistance curve is generated based on the current and voltage; the peak value reached again after the circuit resistance curve drops is the welding clamp circuit resistance value.

[0053] The robot controls the welding clamp to apply pressure, starts the welding controller, and outputs voltage; the current transformer detects the current I, the voltage U is checked through the voltage detection circuit, and the resistance of the welding clamp circuit R = U / I is calculated; the welding controller saves the resistance R curve, and after the resistance of the dynamic resistance curve decreases, it detects the peak value reached when the resistance curve rises again after decreasing, which is the resistance value R of the welding clamp circuit.

[0054] Specifically, such as Figure 4 As shown, when the surface condition of the robot electrode cap is good, the reference resistance curve of the welding clamp circuit is collected; based on the reference resistance curve, the reference resistance value of the welding clamp circuit is determined; the electrode cap of the robot under test is ground, and the current resistance curve of the welding clamp circuit is collected; based on the current resistance curve, the current resistance value of the welding clamp circuit is determined.

[0055] Among them, when a new electrode cap is used and the surface condition of the electrode cap is good, the welding clamp circuit resistance reference curve is collected according to the welding clamp circuit resistance curve acquisition method, and the welding clamp circuit resistance value R0 is detected. Electrode cap grinding status detection: After the robot electrode cap is ground, the current welding clamp circuit resistance curve is collected, and the welding clamp circuit resistance value R1 is detected.

[0056] S104. Compare the reference resistance value with the current resistance value, and determine whether the grinding of the electrode cap of the robot under test is qualified based on the comparison result.

[0057] Specifically, comparing the reference resistance value with the current resistance value and determining whether the grinding of the electrode cap of the robot under test is qualified based on the comparison result also includes:

[0058] Set the resistance limit threshold to Rz, the reference resistance value to R0, and the current resistance value to R1.

[0059] When R1-R0>Rz, the grinding of the electrode cap of the robot under test is deemed unqualified.

[0060] When R1-R0 < Rz, the electrode cap of the robot under test is deemed to have passed the grinding test.

[0061] S106. Set the detection pressure for the welding clamp indentation, and establish a standard welding clamp indentation depth under the detection pressure. The standard welding clamp indentation depth is the average value of multiple welding clamp indentation depths under the condition of good welding clamp alignment.

[0062] Specifically, the number of pressurization cycles is set to n; under the first detection pressure, the welding clamp is pressed in n times, and the average value L1 of the welding clamp pressing depth is calculated; under the second detection pressure, the welding clamp is pressed in n times, and the average value L2 of the welding clamp pressing depth is calculated; then the standard welding clamp pressing depth is set to A0, and A0 = L2 - L1.

[0063] First, a standard welding clamp indentation depth is established as a reference. Under the condition of good welding clamp alignment, 10 pressure F0 pressurizations are performed, the encoder values ​​are recorded, and the average value is calculated as L1 = (L10 + L11 + ... + L19) / 10. The same method is used to perform 10 pressure pressurizations, the encoder values ​​are recorded, and the average value is calculated as L2 = (L20 + L21 + ... + L19) / 10. A0 = L2 - L1, and the reference indentation depth is A0.

[0064] Optionally, assuming good alignment of the welding clamp, the first testing pressure is 500 N, and the second testing pressure is the maximum permissible pressure.

[0065] S108. Under the test pressure, determine the depth of the welding clamp to be tested;

[0066] Among them, the welding alignment detection adopts the welding clamp indentation depth detection method. Two different pressures are measured, the encoder position is recorded, and the current welding clamp indentation depth is calculated. This indentation depth is A1.

[0067] S110. Compare the reference indentation depth and the indentation depth of the welding clamp to determine the alignment of the welding clamp electrode rod. The detection pressure includes a first detection pressure and a second detection pressure. The second detection pressure is greater than the first detection pressure. The welding clamp indentation depth is the difference between the data of the welding clamp servo motor encoder under the first detection pressure and the data of the welding clamp servo motor encoder under the second detection pressure.

[0068] Specifically, set the neutrality threshold Az and the indentation depth of the welding clamp to be tested is A1;

[0069] When A1-A0>Az, the welding clamp is judged to have poor centering.

[0070] When A1-A0 < Az, the welding clamp is judged to be well aligned.

[0071] On the other hand, such as Figure 2 As shown, a robot welding clamp transmission device is provided, comprising:

[0072] Robot body 10;

[0073] The welding clamp 20 includes a first electrode cap 21 and a second electrode cap 22, which are disposed opposite to each other, and the welding clamp is connected to the robot body.

[0074] A robot controller that controls the robot body to move the welding clamp axis of the welding clamp;

[0075] A welding transformer 30 is mounted on a welding clamp and provides power to the welding clamp circuit.

[0076] Servo motor 40 is connected to welding clamp. The servo motor drives the welding clamp to move the first electrode cap by adjusting the pressing depth, thereby adjusting the relative position between the first electrode cap and the second electrode cap.

[0077] Optionally, the robot body 10 includes a mounting bracket 11, and the robot body 10 is connected to the mounting bracket 11; the welding clamp 20 includes a first electrode arm 23, a second electrode arm 24, and an electrode rod 25, the first electrode arm 23 and the servo motor 40 are respectively connected to the mounting bracket 11; the servo motor 40 includes a transmission device 41 and an encoder 42, the transmission device 41 is connected to the second electrode arm 24, the electrode rod 25 is connected to the second electrode arm 24, the first electrode cap 21 is connected to the electrode rod 25, and the second electrode cap 22 is connected to the first electrode arm 23.

[0078] Optionally, such as Figure 3 As shown, it also includes a welding controller 50, a current transformer 60, and a voltage detection circuit 70. The welding controller 50 is connected to the welding transformer 30 to provide it with power. The current transformer 60 is installed on the welding clamp 20 circuit, and the power detection circuit 70 is connected to the welding clamp.

[0079] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An automatic detection method for the status of a robot welding gun, characterized in that, include: Determine the reference resistance value of the welding clamp circuit, and the current resistance value of the welding clamp circuit after the electrode cap of the robot under test has been ground; Compare the reference resistance value with the current resistance value, and determine whether the grinding of the electrode cap of the robot under test is qualified by comparing the comparison results; Set the detection pressure for the welding clamp indentation, and establish a standard welding clamp indentation depth under the detection pressure. The standard welding clamp indentation depth is the average value of multiple welding clamp indentation depths under the condition of good welding clamp alignment. Under test pressure, determine the depth of the welding clamp to be pressed in; By comparing the reference indentation depth and the indentation depth of the welding clamp to be tested, the centering of the welding clamp electrode rod is determined. The detection pressure includes a first detection pressure and a second detection pressure, the second detection pressure being greater than the first detection pressure. The welding clamp indentation depth is the difference between the data of the welding clamp servo motor encoder under the first detection pressure and the data of the welding clamp servo motor encoder under the second detection pressure. Set the number of pressurization cycles to n; Under the first detection pressure, the welding clamp is pressed in n times, and the average value L1 of the welding clamp pressing depth is calculated. Under the second detection pressure, the welding clamp is pressed in n times, and the average value L2 of the welding clamp pressing depth is calculated. If the standard welding clamp insertion depth is set to A0, then A0 = L2 - L1; Set the neutrality threshold Az, and set the indentation depth of the welding clamp to be tested to be A1; When A1-A0>Az, the welding clamp is judged to have poor centering. When A1-A0 < Az, the welding clamp is judged to be well aligned.

2. The automatic detection method for the state of a robotic welding gun according to claim 1, characterized in that, include: Under the condition that the surface of the robot electrode cap is in good condition, the reference resistance curve of the welding clamp circuit is collected. Determine the reference resistance value of the welding clamp circuit based on the reference resistance curve; The electrode caps of the robot under test are ground and the current resistance curve of the welding clamp circuit is collected. Determine the current resistance value of the welding clamp circuit based on the current resistance curve.

3. The automatic detection method for the state of a robot welding gun according to claim 2, characterized in that, include: After applying pressure to the welding clamp, the output voltage is measured, and the current and voltage of the circuit are detected. Generate the loop resistance curve based on current and voltage; The peak value reached again after the loop resistance curve drops is the welding clamp loop resistance value.

4. The automatic detection method for the state of a robotic welding gun according to claim 2, characterized in that, The comparison between the reference resistance value and the current resistance value, and the determination of whether the grinding of the electrode cap of the robot under test is qualified based on the comparison result, also includes: Set the resistance limit threshold to Rz, the reference resistance value to R0, and the current resistance value to R1. When R1-R0>Rz, the grinding of the electrode cap of the robot under test is deemed unqualified. When R1-R0 < Rz, the electrode cap of the robot under test is deemed to have passed the grinding test.

5. The automatic detection method for the state of a robot welding gun according to claim 1, characterized in that, Under the condition that the welding clamp is properly aligned, the first testing pressure is 500N, and the second testing pressure is the maximum permissible pressure.

6. A robotic welding clamp transmission device, employing the automatic detection method for the state of a robotic welding clamp as described in any one of claims 1 to 5, characterized in that, include: The robot itself; A welding clamp, comprising a first electrode cap and a second electrode cap, the first electrode cap and the second electrode cap being disposed opposite to each other, the welding clamp being connected to the robot body; A robot controller that controls the robot body to move the welding clamp axis of the welding clamp; A welding transformer, which is mounted on the welding clamp and provides power to the welding clamp circuit; A servo motor is connected to the welding clamp. The servo motor drives the welding clamp to move the first electrode cap by adjusting the pressing depth, thereby adjusting the relative position between the first electrode cap and the second electrode cap.

7. A robotic welding clamp transmission device according to claim 6, characterized in that, The robot body includes a mounting bracket, and the robot body is connected to the mounting bracket; the welding clamp includes a first electrode arm, a second electrode arm, and an electrode rod, the first electrode arm and the servo motor are respectively connected to the mounting bracket; the servo motor includes a transmission device, the transmission device is connected to the second electrode arm, the electrode rod is connected to the second electrode arm, the first electrode cap is connected to the electrode rod, and the second electrode cap is connected to the first electrode arm.

8. A robotic welding clamp transmission device according to claim 6, characterized in that, It also includes a welding controller, a current transformer, and a voltage detection circuit. The welding controller is connected to the welding transformer to provide it with power. The current transformer is installed on the welding clamp circuit, and the power detection circuit is connected to the electrode arm of the welding clamp.

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