CN115889956A - Method for detecting point position thickness of workpiece by using personal clothing spot welding robot - Google Patents

Abstract

The invention relates to the technical field of automobile manufacturing, in particular to a method for detecting the point position thickness of a workpiece by a customer of a spot welding robot for a customer service, which comprises the steps of calibrating parameters of the spot welding robot for the customer service, deducing the relation between output pressure and displacement, recording the current opening amount, obtaining the thickness of the workpiece, calculating the corresponding offset amount and the like, wherein if the feedback pressure value reaches the set maximum value, and the actual offset amount is smaller than the calculated predicted offset amount in comparison with the offset error, the thickness of the plate is considered to be normal, and the plate can be normally welded. Compared with the prior art, the method and the device can judge whether the given workpiece is the required workpiece thickness or not through the deformation amount and the pressure value of workpiece compression at the same time, do not need to additionally increase hardware, and have high detection reliability and high stability.

Description

Method for detecting point position thickness of workpiece by using personal clothing spot welding robot

Technical Field

The invention relates to the technical field of automobile manufacturing, in particular to a method for detecting the point position thickness of a workpiece by a personal spot welding robot.

Background

Spot welding is an efficient, economical and important joining method, commonly found in assembly shops for automotive bodies. Spot welding is one kind of resistance welding, and includes pressurizing with two upper and lower cylindrical electrodes, pressing the workpiece to be welded between the two electrodes, applying electric current to the electrodes, and heating to melt the base metal with the resistance to form welding spot.

Materials with different thicknesses in the spot welding process have different required currents and corresponding pressures, so that the change of the actual pressure feedback between the two electrodes needs to be detected in real time during welding to judge whether the plate workpiece is a correspondingly welded plate. If the welded plate is too thin or too thick, the quality of the weld is affected.

In the prior art, the thickness of a welding workpiece is considered to be a workpiece corresponding to welding by default, or the thickness of the workpiece is judged by a visual sensor or the welding quality is judged by a visual camera after the welding is finished, and the thickness of the workpiece is judged by the visual sensor, so that the method needs to be provided with an additional visual angle system and has higher cost; and the visual sensor has higher requirement on light, and when a plurality of welding spots are welded, different lighting visual judgment effects of different point positions are different, and the detection accuracy is not high.

Disclosure of Invention

In view of the above, the invention provides a method for detecting the point location thickness of a workpiece by a private spot welding robot, which adopts the following technical scheme:

a method for detecting the point location thickness of a workpiece by a personal spot welding robot comprises the following steps:

1) Firstly, calibrating parameters of a spot welder for personal clothing, wherein the parameters comprise an acceleration ratio and a running speed so as to ensure that output pressure is in direct proportion to a compression offset;

2) Before the teaching of spot welding, the pressure gauge is used for calibrating for multiple times to form a relation table of output pressure, torque of a servo motor and displacement, and the relation between the output pressure and the displacement is deduced after the least square method is used for fitting data, so that the method is convenient to use in the detection process;

3) The upper electrode and the lower electrode of the movable spot welder are contacted and combined, and the current opening amount is recorded;

4) The position of the fixed plate is prohibited from moving, the spot welding robot is moved to the position of a teaching workpiece, and the lower electrode is moved upwards to the bottom of the plate to be contacted;

5) Moving the movable upper electrode to close the mouth, contacting with the top of the plate, recording the mouth opening amount, performing difference calculation with the mouth opening amount recorded in the step 3) to obtain the thickness of the workpiece, and recording the current teaching point position information;

6) Setting corresponding parameters according to the material and thickness of the plate, setting the required pressure in a key manner, and calculating the corresponding offset according to the pressure value and a pressure displacement relation table;

7) After the welding instruction is operated, the welding gun moves to the teaching point position in the step 5), and the upper electrode and the lower electrode touch the upper surface and the lower surface of the plate;

8) Starting to execute a pressurizing process, wherein in the compressing process, as the maximum feedback pressure of continuous compression is not reached, the servo motor can continuously apply pressure until the set maximum torque value;

9) Continuously recording the pressure value and the offset output in each period in the whole process;

10 If the actual offset is too small compared with the calculated predicted offset after the feedback pressure value reaches the set maximum value, an alarm is given to indicate that the plate workpiece is too thick;

11 If no significant change in the feedback pressure is detected in a plurality of cycles before the expected offset is reached, and the actual offset is too much offset compared with the calculated expected offset, an alarm is raised to indicate that the plate workpiece is too thin;

12 If the feedback pressure value has reached the set maximum value and the actual offset is less in offset error than the calculated expected offset, the sheet thickness is considered normal and welding can be performed normally.

Compared with the prior art, the method and the device can judge whether the given workpiece is the required workpiece thickness or not through the deformation amount and the pressure value of workpiece compression at the same time, do not need to additionally increase hardware, and have high detection reliability and high stability.

Detailed Description

The present invention is further described below.

A method for detecting the point location thickness of a workpiece by a personal clothing spot welding robot comprises the following steps:

1) Firstly, calibrating parameters of a spot welder for the personal clothing, wherein the parameters comprise an acceleration ratio and a running speed so as to ensure that the output pressure is in direct proportion to the compression offset;

2) Before the teaching of spot welding, the pressure gauge is used for calibrating for multiple times to form a relation table of output pressure, torque of a servo motor and displacement, and the relation between the output pressure and the displacement is deduced after the least square method is used for fitting data, so that the method is convenient to use in the detection process; for example, the following table of torque, pressure and displacement is obtained in this example:

3) The upper electrode and the lower electrode of the movable spot welder are contacted and combined, and the current opening amount is recorded;

4) The position of the fixed plate is forbidden to move, the spot welding robot is moved to the position of a teaching workpiece, and the lower electrode is moved upwards to the bottom of the plate to be contacted;

5) Moving the movable upper electrode to close the mouth, contacting with the top of the plate, recording the mouth opening amount, performing difference calculation with the mouth opening amount recorded in the step 3) to obtain the thickness of the workpiece, and recording the current teaching point position information;

6) Setting corresponding parameters according to the material and thickness of the plate, setting the required pressure in a key manner, and calculating the corresponding offset according to the pressure value and a pressure displacement relation table;

7) After the welding instruction is operated, the welding gun moves to the teaching point position in the step 5), and the upper electrode and the lower electrode touch the upper surface and the lower surface of the plate;

8) Starting to execute a pressurizing process, wherein in the compressing process, as the maximum feedback pressure of continuous compression is not reached, the servo motor can continuously apply pressure until the set maximum torque value;

9) Continuously recording the pressure value and the offset output in each period in the whole process;

10 If the actual offset is too small compared with the calculated predicted offset after the feedback pressure value reaches the set maximum value, an alarm is given to indicate that the plate workpiece is too thick;

11 If no significant change in the feedback pressure is detected in a plurality of cycles before the expected offset is reached, and the actual offset is too much offset compared with the calculated expected offset, an alarm is raised to indicate that the plate workpiece is too thin;

12 If the feedback pressure value has reached the set maximum value and the actual offset is less in offset error than the calculated expected offset, the sheet thickness is considered normal and welding can be performed normally.

The invention has not been described in detail in relation to the prior art or common general knowledge in the field.

Claims (1)

1. A method for detecting the point location thickness of a workpiece by a personal clothing spot welding robot is characterized by comprising the following steps:

1) Firstly, calibrating parameters of a spot welder for personal clothing, wherein the parameters comprise an acceleration ratio and a running speed so as to ensure that output pressure is in direct proportion to a compression offset;

2) Before the spot welding teaching, the pressure gauge is used for calibrating for multiple times to form a relation table of output pressure, private clothes motor torque and displacement, and the relation between the output pressure and the displacement is deduced after the least square method is used for fitting data, so that the method is convenient to use in the detection process;

3) The upper electrode and the lower electrode of the movable spot welder are contacted and combined, and the current opening amount is recorded;

4) The position of the fixed plate is prohibited from moving, the spot welding robot is moved to the position of a teaching workpiece, and the lower electrode is moved upwards to the bottom of the plate to be contacted;

5) Moving the movable upper electrode to close the mouth, contacting with the top of the plate, recording the mouth opening amount, performing difference calculation with the mouth opening amount recorded in the step 3) to obtain the thickness of the workpiece, and recording the current teaching point position information;

6) Setting corresponding parameters according to the material and thickness of the plate, setting the required pressure in a key manner, and calculating the corresponding offset according to the pressure value and a pressure displacement relation table;

7) After the welding instruction is operated, the welding gun moves to the teaching point position in the step 5), and the upper electrode and the lower electrode touch the upper surface and the lower surface of the plate;

8) Starting to execute a pressurizing process, wherein in the compressing process, as the maximum feedback pressure of continuous compression is not reached, the servo motor can continuously apply pressure until the set maximum torque value;

9) Continuously recording the pressure value and the offset output in each period in the whole process;

10 If the actual offset is too small compared with the calculated predicted offset after the feedback pressure value reaches the set maximum value, an alarm is given to indicate that the plate workpiece is too thick;

11 If no significant change in the feedback pressure is detected in a plurality of cycles before the expected offset is reached, and the actual offset is too much offset compared with the calculated expected offset, an alarm is raised to indicate that the plate workpiece is too thin;

12 If the feedback pressure value has reached the set maximum value and the actual offset is less in offset error than the calculated expected offset, the sheet thickness is considered normal and welding can be performed normally.