阅读说明：本技术 一种基于伺服电机驱动的电阻点焊机加压控制方法 (Resistance spot welding machine pressurization control method based on servo motor drive ) 是由 袁忠杰 于 2021-08-12 设计创作，主要内容包括：本发明公开了一种基于伺服电机驱动的电阻点焊机加压控制方法,其特征在于：采用伺服电机驱动点焊机的焊动臂向焊静臂移动将焊动臂与焊静臂之间的待焊接工件夹紧焊接,通过伺服电机驱动焊动臂的位移使得焊静臂产生相应的形变量进而精确控制工件的焊接压力。本发明在焊接过程中,由于焊静臂具有完美结构弹性体以及电极位置高精度标定校正的特点,焊静臂的形变量与设计焊接压力存在着对应关系进而精确控制压力,使得压力控制更加精确,进而完美保证了焊接工艺品质；通过控制焊静臂的形变量完全消除了传动机构各种阻力对焊接压力精确控制造成控制精度差的问题,尤其是在低压力焊接效果显著。(The invention discloses a resistance spot welding machine pressurization control method based on servo motor driving, which is characterized by comprising the following steps of: the servo motor is adopted to drive the welding movable arm of the spot welding machine to move towards the welding static arm so as to clamp and weld the workpiece to be welded between the welding movable arm and the welding static arm, and the servo motor is used to drive the welding movable arm to move so that the welding static arm generates corresponding deformation and further accurately controls the welding pressure of the workpiece. In the welding process, the welding static arm has the characteristics of a perfect-structure elastomer and high-precision calibration and correction of the electrode position, and the deformation quantity of the welding static arm has a corresponding relation with the designed welding pressure so as to accurately control the pressure, so that the pressure control is more accurate, and the quality of the welding process is perfectly ensured; the problem of poor control precision caused by various resistances of a transmission mechanism to the precise control of welding pressure is completely solved by controlling the deformation of the welding static arm, and the welding static arm has obvious effect particularly in low-pressure welding.)

1. A resistance spot welding machine pressurization control method based on servo motor driving is characterized in that: the servo motor is adopted to drive the welding movable arm of the spot welding machine to move towards the welding static arm so as to clamp and weld the workpiece to be welded between the welding movable arm and the welding static arm, and the servo motor is used to drive the welding movable arm to move so that the welding static arm generates corresponding deformation and further accurately controls the welding pressure of the workpiece.

2. The resistance spot welding machine pressurization control method based on servo motor driving according to claim 1, characterized in that: the deformation of the welding static arm is in a corresponding relation with the designed welding pressure, and is determined according to the following formula:

ΔS＝S-L+D

in the first formula: s is the displacement of the welding movable arm under the designed welding pressure, L is the distance between the movable electrode on the welding movable arm and the end part of the static electrode on the welding static arm when the welding movable arm is at the initial position, D is the total welding thickness of the workpiece to be welded, and Delta S is the deformation quantity of the welding static arm caused by the elastic deformation of the welding static arm.

3. The resistance spot welding machine pressurization control method based on servo motor driving according to claim 1, characterized in that: in the welding process, the deformation amount of the welding static arm is controlled by driving the welding movable arm to move, so that the welding pressure is adjusted, and the welding pressure can be adjusted and controlled in the welding process.

4. The resistance spot welding machine pressurization control method based on servo motor driving according to claim 1, characterized in that: before welding, calibrating and correcting the reference position between a moving electrode on the welding movable arm and a static electrode on the welding static arm periodically.

5. The resistance spot welding machine pressurization control method based on servo motor driving according to claim 4, characterized in that: the calibration correction is to calibrate the position of the moving electrode on the welding movable arm moving towards the static electrode on the welding static arm at the touch contact position as a relative reference point for calculating the distance between the end parts of the moving electrode and the static electrode to be zero, and correct the position of the welding static arm according to the calibrated relative reference point position.

6. The resistance spot welding machine pressurization control method based on servo motor driving according to claim 4, characterized in that: the calibration correction is to place the workpiece to be welded between the moving electrode and the static electrode, drive the moving electrode to move towards the static electrode, so that the moving electrode is used as a reference point when the workpiece and the static electrode are in short circuit, and the position at the moment is determined as a reference position where the workpiece starts to apply welding pressure.

7. The resistance spot welding machine pressurization control method based on servo motor driving according to claim 1, characterized in that: in the welding process, after the displacement position of the welding arm is adjusted and stabilized, the current value of the servo motor is acquired in real time, and the current pressure value is directly and accurately reflected through the corresponding relation between the current value of the servo motor and the welding pressure.

8. A resistance spot welding machine welding method based on servo motor driving, which adopts the resistance spot welding machine pressurization control method based on servo motor driving according to claim 1, and is characterized in that: the welding method comprises the following steps:

the method comprises the following steps that a workpiece is placed between a moving electrode on a welding movable arm and a static electrode on a welding static arm, the servo motor drives the welding movable arm to move and move so that the moving electrode and the static electrode clamp and weld the workpiece, the servo motor drives the welding movable arm to move in a welding process so that the welding static arm generates corresponding deformation, and welding pressure of the workpiece is accurately controlled, and the deformation of the welding static arm corresponds to the designed welding pressure;

wherein, the deformation of the welding static arm is determined according to the following formula:

Δ S ═ S-L + D (a formula)

In the first formula: s is the displacement of the welding movable arm under the designed welding pressure, L is the distance between the movable electrode on the welding movable arm and the end part of the static electrode on the welding static arm when the welding movable arm is at the initial position, D is the total welding thickness of the workpiece to be welded, and Delta S is the deformation quantity of the welding static arm caused by the elastic deformation of the welding static arm;

and after the welding is electrified for a certain time, controlling the servo motor to drive the welding arm to return to the initial position, and completing one welding cycle.

9. The resistance spot welding machine welding method based on servo motor driving as claimed in claim 8, characterized in that: in the welding process, the deformation amount of the welding static arm is controlled by driving the welding movable arm to move, so that the welding pressure is adjusted, and the welding pressure can be adjusted and controlled in the welding process.

The technical field is as follows:

the invention relates to the technical field of resistance welding, in particular to a resistance spot welding machine pressurization control method based on servo motor driving.

Background art:

resistance welding is a welding method in which a workpiece is locally heated by using resistance heat generated by passing a current through the workpiece and a contact surface as heat input, and the workpiece needs to be pressurized by a welding tongs.

In the process of resistance spot welding, a welding clamp is needed to pressurize a welding workpiece; in the existing resistance welding, a piston type cylinder is generally adopted to control the welding pressure by using the air pressure in the cylinder, or a servo press is adopted to control the output of the pressure by using the torque of a motor, and the output is indirectly transmitted to a welding clamp electrode through a transmission mechanism to be pressurized. In practical use, the pressure transmitted to the welding electrode is unstable due to resistance change during movement and abrasion between transmission parts, so that the pressure control precision is poor, and particularly in the case of low pressure, the transmission resistance is in a large proportion to the driving force, so that the control precision is even worse. Meanwhile, in the prior art, a pressure sensor is adopted for detecting welding pressure and controlling the welding pressure according to a detection result, but the mode is complex in installation, complex in control and poor in stability.

In the technical field of resistance welding, the control of the welding pressure precision is an important factor influencing the quality of a joint, and the phenomena of splashing, too large and too small indentation diameter, unattractive nugget forming and the like are easily caused in the welding process due to poor pressure control precision in the welding process, so that the welding process is directly influenced, the welding process is not perfect, and the stable good welding quality cannot be ensured. And the clamp can have the arm lock deformation after long-time use, and the deformation is difficult to recover for welding precision is lower and lower, thereby leads to product quality unstability, and welding repeatability is not high.

The invention content is as follows:

the invention aims to solve the defects and provides a resistance spot welding machine pressurization control method based on servo motor driving.

The invention provides a resistance spot welding machine pressurization control method based on servo motor driving, which is characterized by comprising the following steps:

the servo motor is adopted to drive the welding movable arm of the spot welding machine to move towards the welding static arm so as to clamp and weld the workpiece to be welded between the welding movable arm and the welding static arm, and the servo motor is used to drive the welding movable arm to move so that the welding static arm generates corresponding deformation and further accurately controls the welding pressure of the workpiece.

In the welding process, a movable electrode is fixedly connected to a welding arm, a static electrode is fixedly connected to the welding static arm, the welding arm moves to enable the movable electrode and the static electrode to clamp a workpiece, the welding arm continues to move towards the welding static arm to clamp displacement variation so that the welding static arm generates deformation, the displacement after the welding arm clamps and the deformation of the welding static arm have a corresponding relation, namely, the welding arm generates certain displacement after clamping, the welding static arm correspondingly generates certain deformation, the stress-strain corresponding relation exists between the deformation (corresponding strain) of the welding static arm and the welding pressure (corresponding stress), namely, the displacement of the welding arm is driven to enable the welding static arm to generate corresponding deformation and the designed welding pressure have a corresponding relation, and the deformation generated by the welding static arm is driven to accurately control the welding pressure of the workpiece by the servo motor in a position mode, thereby making the control convenient and accurate.

Furthermore, because the deformation of the welding static arm has a corresponding relation with the designed welding pressure, the deformation of the welding static arm is determined according to the following formula:

Δ S ═ S-L + D (a formula)

In the first formula: s is the displacement of the welding movable arm under the designed welding pressure, L is the distance between the movable electrode on the welding movable arm and the end part of the static electrode on the welding static arm when the welding movable arm is at the initial position, D is the total welding thickness of the workpiece to be welded, and Delta S is the deformation quantity of the welding static arm caused by the elastic deformation of the welding static arm. The value of the displacement S driven by the welding arm is the displacement of the movement of the welding arm measured by experiments under the condition of the designed welding pressure of a standard welding workpiece.

Furthermore, in the welding process, the deformation amount of the welding static arm is controlled by driving the welding movable arm to move, so that the welding pressure is adjusted, and the welding pressure can be adjusted and controlled in the welding process.

Furthermore, before welding, calibration correction is periodically carried out on the reference position between the movable electrode on the welding movable arm and the static electrode on the welding static arm.

Further, the calibration correction is to calibrate the position of the moving electrode on the welding arm moving towards the static electrode on the welding static arm and contacting with the static electrode at the touch contact position as a relative reference point for calculating the distance between the moving electrode and the end part of the static electrode to be zero, and correct the position of the welding static arm according to the calibrated relative reference point position. Wherein the touch contact between the movable electrode and the static electrode can be judged by short circuit between the electrodes. By means of the method for periodically calibrating and correcting before welding, the influence of deformation generated by long-time use of the welding movable arm or the welding static arm on welding precision is avoided, and the pressure control precision in the welding process is more accurate.

In another scheme, the calibration correction is to place the workpiece to be welded between the moving electrode and the static electrode, drive the moving electrode to move towards the static electrode, so that the moving electrode is used as a reference point when the workpiece and the static electrode are short-circuited, and the position at the moment is determined as a reference position where the workpiece starts to apply welding pressure.

Furthermore, in the welding process, after the displacement position of the welding arm is adjusted stably, the current value of the servo motor is acquired in real time, and the current pressure value is directly and accurately reflected through the corresponding relation between the current value of the servo motor and the welding pressure.

In the process of controlling the welding pressure, after the displacement of the welding arm reaches the stable welding position, the current welding pressure change can be accurately reflected by acquiring the current value change of the servo motor in real time, the real-time pressure change state can be directly reflected, and support data are provided for improving the welding process. In actual welding, after entering the welding stage, the welding pressure change in the welding process can make servo motor's electric current change, through observing servo motor electric current value change, can real-time supervision nugget's shaping change.

The invention also provides a resistance spot welding machine welding method based on servo motor driving, which adopts the resistance spot welding machine pressurization control method based on servo motor driving, and the welding method comprises the following steps:

the method comprises the following steps that a workpiece is placed between a moving electrode on a welding movable arm and a static electrode on a welding static arm, the servo motor drives the welding movable arm to move so that the moving electrode and the static electrode clamp and weld the workpiece, the servo motor drives the welding movable arm to move so that the welding static arm generates corresponding deformation in the welding process, the welding pressure of the workpiece is accurately controlled, and the deformation of the welding static arm corresponds to the designed welding pressure;

wherein, the deformation of the welding static arm is determined according to the following formula:

Δ S ═ S-L + D (a formula)

In the first formula: s is the displacement of the welding movable arm under the designed welding pressure, L is the distance between the movable electrode on the welding movable arm and the end part of the static electrode on the welding static arm when the welding movable arm is at the initial position, D is the total welding thickness of the workpiece to be welded, and Delta S is the deformation quantity of the welding static arm caused by the elastic deformation of the welding static arm; the value of the displacement S driven by the welding arm is the displacement of the movement of the welding arm measured by experiments under the condition of the set welding pressure of a standard welding workpiece.

And after the welding is electrified for a certain time, controlling the servo motor to drive the welding arm to return to the initial position, and completing one welding cycle. In the welding method, the deformation amount of the welding static arm is controlled by driving the welding movable arm to move in the welding process so as to adjust the welding pressure, so that the welding pressure can be adjusted and controlled in the welding process.

The invention discloses a resistance spot welding machine pressurization control method based on servo motor driving, which has the following beneficial effects:

1. the servo motor drives the welding movable arm to move in a position mode, so that the deformation quantity generated by the welding static arm is generated, and the deformation quantity of the welding static arm has a corresponding relation with the designed welding pressure so as to control the welding pressure of the workpiece. The welding static arm has the characteristics of a perfect structure elastomer and high-precision calibration and correction of the electrode position before welding, deformation of the welding static arm is controlled to achieve accurate control of welding pressure in the welding process, the influence of various resistances of a transmission mechanism on pressure accurate control in the prior art is completely eliminated, and particularly, the problem of poor pressure control precision caused by the fact that the relative ratio of the resistance to the welding pressure is large in a torque control mode during low-pressure welding is avoided under the condition of low-pressure welding.

2. By utilizing the characteristics of high precision and quick response of the servo motor in a position mode, when the displacement adjustment of the welding arm is stable, the current value of the servo motor is acquired in real time, the current value and the welding pressure have a one-to-one correspondence relationship after the stabilization, the current welding pressure change is accurately reflected by observing the change of the current value of the servo motor, a pressure sensor is replaced, the forming of a nugget can be monitored in real time, the technological process can be accurately controlled, and the welding quality is perfectly ensured.

3. In the welding process, the deformation amount of the welding static arm is controlled by driving the welding movable arm to move, so that the welding pressure is adjusted, and the welding pressure can be adjusted and controlled in the welding process.

Drawings

Fig. 1 is an exemplary apparatus structure for applying a pressurization control method for a resistance spot welding machine based on servo motor driving according to an embodiment of the present disclosure.

Fig. 2 is a schematic diagram of relative positions of a moving electrode and a static electrode in a welding process of an exemplary device structure applying a pressurization control method of a resistance spot welding machine based on servo motor driving according to an embodiment of the disclosure.

Fig. 3 is a schematic view illustrating a current variation trend of the servo motor according to an embodiment of the disclosure.

The reference numbers in the figures illustrate: 1. a soldering turret body; 2. welding a static arm; 3. welding a movable arm; 4. a moving electrode; 5. a static electrode; 6. a servo motor; 7. driving the screw rod; 8. a feed screw nut; 9. and (5) welding the workpiece.

Detailed Description

The present invention is further illustrated by the following examples, which are carried out on the premise of the technical solution of the present invention, and detailed embodiments and specific procedures are given, but the scope of the present invention is not limited to the following examples.

Summary of the invention:

welding current, energization time and pressure are three conditions of resistance welding. The first two conditions are very important because they can be controlled with high precision and ideally by a resistance welding high current tester, compared with which the control of pressure is much more difficult than it is. In the existing resistance welding, a piston type cylinder is generally adopted to control the air pressure by utilizing the stroke of a piston rod, or a servo press is adopted to control the output of pressure by utilizing the torque of a motor, and then the pressure is indirectly transmitted to a welding tongs electrode through a transmission mechanism to be pressurized. In the mode, the welding pressure reaching the electrode is reduced due to the resistance and the abrasion loss of the transmission mechanism, and after the welding device is used for a period of time, the resistance and other resistance of the transmission mechanism can change along with the change of the time, so that the welding pressure is further unstable, and the welding quality is influenced; particularly in the case of welding at a low welding pressure, the specific gravity of the resistance to the welding pressure becomes large, so that the error of the welding pressure becomes larger. The deformation amount of the welding static arm is controlled by adopting the servo motor to drive the displacement of the welding movable arm, so that the welding pressure of the workpiece is controlled. The servo motor drives the welding movable arm to move so that the deformation quantity generated by the welding static arm can be more accurately controlled without being influenced by the resistance; and the deviation generated by long-time work is overcome by regular and simple calibration and correction.

The method comprises the following steps:

a resistance spot welding machine pressurization control method based on servo motor driving is characterized in that:

the servo motor is adopted to drive the welding movable arm of the spot welding machine to move towards the welding static arm so as to clamp and weld the workpiece to be welded between the welding movable arm and the welding static arm, and the servo motor is used to drive the welding movable arm to move so that the welding static arm generates corresponding deformation and further accurately controls the welding pressure of the workpiece.

As shown in fig. 1 and 2, during welding, a movable electrode 4 is fixedly connected to a welding arm 3, a static electrode 5 is fixedly connected to a welding static arm 2, the welding arm moves to clamp a workpiece 9 between the movable electrode 4 and the static electrode 5, and then the welding arm continues to move in the direction of the welding static arm to clamp a displacement variation so that the welding static arm generates a deformation Δ S, and the displacement after the welding arm clamps and the deformation of the welding static arm have a corresponding relationship, that is, the welding arm clamps and generates a certain displacement, the welding static arm correspondingly generates a certain deformation, and a stress-strain corresponding relationship exists between the deformation Δ S (corresponding strain) of the welding static arm and a welding pressure F (corresponding stress), that is, the displacement of the welding arm causes the corresponding deformation Δ S of the welding static arm to correspond to a design welding pressure F, and the displacement of the welding static arm is driven by a servo motor 6 in a position mode so that the deformation Δ S of the welding static arm can accurately control the welding pressure of the workpiece Thereby the control is convenient and accurate.

Before welding, as shown in fig. 1 and fig. 2, the servo electrode 6 is controlled to drive the welding movable arm 3 to move towards the static electrode 5 on the welding static arm 2 for calibration correction; an exemplary calibration and correction method is to make the moving electrode 4 slowly approach the static electrode 5, when the circuit is short-circuited due to the touch of the moving electrode 4, calibrate the position as a standard reference point and calculate a relative reference point with a zero distance between the ends of the moving electrode 4 and the static electrode 5, and then correct the position of the welding static arm according to the calibrated relative reference point position. The touch contact between the movable electrode 4 and the static electrode 5 can be judged through short circuit between the electrodes, and then the high-precision calibration and correction of the electrode position can be achieved.

As shown in fig. 2, the total thickness D of the welding workpiece can be measured directly by a gauge or by a method of contact of a welding arm: the method comprises the steps of placing a workpiece 9 to be welded between a moving electrode 4 and a static electrode 5, driving the moving electrode 4 to move towards the static electrode 5, and when the moving electrode 4 touches and contacts the workpiece 9 and the static electrode 5 is in short circuit, the distance between the moving electrode 4 and the static electrode 5 is the total thickness D of the welded workpiece, and the position of the moving electrode 4 is the position where the welding arm starts to pressurize after the workpiece 9 is clamped by the moving electrode 4 and the static electrode 5.

The corresponding deformation quantity delta S generated by the welding static arm corresponds to the designed welding pressure F, experimental data of a standard welding workpiece are obtained under the condition of the designed welding pressure, specifically, the deformation quantity delta S generated by the welding static arm is obtained by measuring the movable electrode extrusion static electrode of the standard welding workpiece through an experiment, and the welding pressure F under the corresponding deformation quantity delta S is measured. In one embodiment, the deformation Δ S of the welding static arm of the electrode holder of a resistance spot welding machine, such as a C-type, corresponds to the variation of the welding pressure F as follows:

static arm deformation (Delta S) mm	Welding pressure F
		0.372	1000
1.114	3000
		1.900	5000
2.694	7200

Specifically, in the welding pressure control process, the deformation amount Δ S of the welding static arm is calculated according to the following formula:

Δ S ═ S-L + D (a formula)

In the formula: s is the displacement of the welding movable arm drive under the designed welding pressure, L is the distance between the movable electrode on the welding movable arm and the static electrode end on the welding static arm when in the initial position, D is the total welding thickness of the workpiece to be welded, and Delta S is the deformation quantity of the welding static arm caused by the elastic deformation of the welding static arm.

L in the formula is calibrated through calibration, the total thickness D of the welding workpiece can be directly measured through a measuring tool or can be measured through a calibration and calibration method, S is the displacement of the welding arm under the designed welding pressure, and therefore the deformation quantity delta S of the welding static arm is an accurate and determined value.

Due to the characteristic of high-precision displacement control of the servo motor in the position mode, the corresponding static welding arm deformation quantity is set according to the characteristics of the thickness and the like of a welding workpiece, so that the welding pressure is accurately controlled, the problem that in the prior art, the pressure output is influenced by various resistances of a transmission mechanism to the accurate control of the pressure is solved, and the effect is more obvious particularly under the condition of low-pressure welding.

The positions of a moving electrode on the welding movable arm and a static electrode on the welding static arm are calibrated and corrected regularly before welding, so that the influence of deformation generated by long-time use of the welding movable arm or the welding static arm on welding precision is avoided, and the pressure control precision in the welding process is more accurate.

Specifically, in the welding process, the deformation amount of the welding static arm is controlled by driving the welding movable arm to move, so that the welding pressure is adjusted, and the welding pressure can be adjusted and controlled in the welding process.

As shown in fig. 3, after the displacement position of the welding arm is adjusted and stabilized, the current of the servo motor is in a relatively stable state, the trend of the change curve is shown in the rear section of fig. 3, the current value of the servo motor is acquired in real time, and the current pressure value is directly and accurately reflected through the corresponding relationship between the current value of the servo motor and the welding pressure. In actual welding, after entering the welding stage, the welding pressure change in the welding process can make servo motor's electric current change, through observing servo motor electric current value change, can real-time supervision nugget's shaping change.

The invention utilizes the characteristics of high precision and quick response of the servo motor in the position mode, accurately reflects the current welding pressure change by observing the change of the current value of the servo motor, replaces a pressure sensor, does not need to additionally add detection elements such as the pressure sensor and the like, reduces the cost, avoids the problem that the detection precision of the pressure sensor is not accurate enough due to the creep deformation of a welding movable arm or a welding static arm, and simultaneously can monitor the formation of a nugget in real time, so that the welding process can be accurately controlled, and the welding quality is perfectly ensured.

Meanwhile, corresponding displacement compensation can be carried out, so that the deformation of the welding static arm is controlled to adjust the welding pressure, and the high-precision control of the welding pressure in the welding process is further improved.

As shown in fig. 1, the disclosure provides an exemplary welding device structure of a resistance spot welding machine applying the pressurizing control method based on servo motor driving.

As shown in fig. 1, an exemplary system architecture includes a welding clamp body 1, a static welding arm 2 is fixedly connected to the welding clamp body 1, a movable welding arm 3 is slidably connected to the welding clamp body 1, and a movable electrode 4 is fixedly connected to the movable welding arm 3; the static welding arm 2 is fixedly connected with a static electrode 5, a moving electrode 4 and the static electrode 5 are respectively and electrically connected with a welding power supply, and the moving electrode 4 and the static electrode 5 are oppositely arranged;

the welding tongs comprises a welding tongs body 1, a servo motor 6, a driving screw 7, a screw nut 8, a ball screw, and a welding arm 3, wherein the servo motor 6 is fixedly installed on the welding tongs body 1, an output shaft of the servo motor 6 is fixedly connected with the driving screw 7, the driving screw 7 is connected with the screw nut 8, the screw nut 8 is matched with the driving screw 7 to form the ball screw, and the welding arm is fixedly connected to the screw nut 8.

Before welding, the servo electrode 6 is controlled to drive the welding movable arm 3 to move towards the static electrode 5 on the welding static arm 2 for calibration and correction, and relative reference points with zero distance between the ends of the movable electrode 4 and the static electrode 5 are respectively calibrated; and the deformation quantity delta S of the welding static arm caused by the elastic deformation of the welding static arm under the designed welding pressure is obtained through experiments.

During welding, a workpiece is placed between a moving electrode on a welding arm and a static electrode on a welding static arm, the servo motor drives the welding arm to move so that the moving electrode and the static electrode clamp and weld the workpiece, the servo motor drives the welding arm to move so that the welding static arm generates corresponding deformation in the welding process, and then the welding pressure of the workpiece is accurately controlled, and the deformation of the welding static arm corresponds to the designed welding pressure;

specifically, in the welding pressure control process, the deformation amount Δ S of the welding static arm is calculated according to the following formula:

Δ S ═ S-L + D (a formula)

In the formula: s is the displacement of the welding movable arm drive under the designed welding pressure, L is the distance between the movable electrode on the welding movable arm and the static electrode end on the welding static arm when in the initial position, D is the total welding thickness of the workpiece to be welded, and Delta S is the deformation quantity of the welding static arm caused by the elastic deformation of the welding static arm.

And after the welding is electrified for a certain time, controlling the servo motor to drive the welding arm to return to the initial position, and completing one welding cycle. The servo motor drives the displacement of the welding movable arm in a position mode, deformation generated by the welding static arm is accurately controlled, and then the welding pressure of a workpiece is controlled, the control precision is high, the welding pressure is more stable, the consistency and repeatability of a welding product can be guaranteed, the welding quality is obviously improved, and the robot welding automation is favorably realized, and the production efficiency is improved.

In another embodiment, during welding, the deformation amount of the welding static arm is controlled by driving the welding movable arm to move so as to adjust the welding pressure, so that the welding pressure can be adjusted and controlled during welding.

In order to optimize better welding process quality, the deformation quantity of the welding static arm is adjusted at different stages, the displacement quantity S of the welding static arm is a variable which is changed in welding, the deformation quantity of the welding static arm is adjusted through the change of the displacement in welding so as to adjust welding pressure, the welding pressure is controlled to be changed, welding parameters are adjusted, and welding quality is improved.

The control method is not only used in the structure of the embodiment, but also can be applied to the welding pressure control of the electric welding machine of the X-shaped welding tongs. And the control method of the present application is not limited to be driven by a servo motor, and other driving mechanisms for accurately controlling displacement are all within the protection scope of the claims of the present application.

The foregoing is merely an example of the present invention and common general knowledge of features in the schemes is not described here in any greater extent. It should be noted that, for a person skilled in the art, several modifications can be made without departing from the invention, which should also be considered as the protection scope of the invention.