CN105750694B - Based on magnetic control rotating arc sensor from the complex-curved overlaying method in pathfinding footpath - Google Patents

Abstract

The invention discloses a surfacing welding method for self-seeking complex curved surfaces based on magnetron rotating arc sensing. The main principle of this method is to use the magnetron rotating arc sensor to scan the curved surface, collect the current signal of the sampling point through the Hall sensor, divide the sampling points of each rotation cycle into intervals and directions by the directional interval sensor, and calculate the interval and direction of each interval by the arithmetic processor. The average current of the sampling period is filtered and the direction of the minimum average current of the sampling period is determined. At the same time, the position compensation controller automatically adjusts the height of the welding torch by comparing the sampling period with the average current value of the reference period, stably avoiding arc break and torch collision; The shaft linkage welding machine ensures that the welding direction faces the corresponding direction of the sampling group with the smallest current average current, so that the welding is always carried out at the lower level of the curved surface until the average current in each interval of the sampling period fluctuates very little, and it is judged that the current curved surface has tended to be flat , the surfacing of the curved surface is completed.

Description

Surfacing welding method for complex curved surface with self-seeking path based on magnetron rotating arc sensor

technical field

The invention relates to the field of automation, and relates to a method for surfacing welding of complex curved surfaces with self-seeking paths based on magnetron rotating arc sensing.

Background technique

Welding is a commonly used manufacturing process and technology, and surfacing welding, as an economical and fast process method for surface modification of materials, is more and more widely used in the manufacture, repair and surface modification technology of parts and components in various industrial sectors . In the actual surfacing process, the surface of the workpiece to be welded is basically required to be flat. When the surface shape of the workpiece is complex, such as a curved surface, the traditional surfacing process cannot be directly applied, and the automation of the surfacing process is low, requiring manual real-time adjustment. In order to ensure the surfacing work. In order to solve the technical difficulties of surfacing welding under complex curved surface conditions, a method of self-seeking complex curved surface surfacing welding based on magnetron rotating arc sensing is proposed, which has a positive effect on further promoting the automation of surfacing welding process.

Contents of the invention

In order to solve the shortcomings of the existing technology and better promote the automatic development of the surfacing welding process, in the current surfacing welding production line, the surfacing welding of workpieces with complex curved surfaces can only be done manually, resulting in poor surfacing welding effect , the quality and thickness of the surfacing layer cannot meet the requirements, etc., a self-seeking path-finding complex curved surface surfacing method based on magnetron rotating arc sensing is proposed. : Magnetically controlled rotating arc sensor, directional zone sensor, arithmetic controller, position compensation controller, four-axis linkage welding machine; this method divides the sampling zone and position direction through the directional zone sensor, collects welding current according to the magnetically controlled arc sensor, The arithmetic controller calculates the direction corresponding to the sampling group with the smallest average current, and the four-axis linkage welding machine controls the welding torch to always weld along the direction with the smallest average current, that is, the direction with the lowest surface level. In the subsequent cyclic sampling and positioning process, when the average When the fluctuation of the current change is less than or equal to the reference interval, the surfacing welding of the current curved surface is completed. The unevenness of the curved surface is filled by continuous welding until the entire curved surface is completely flattened; at the same time, the position compensation controller ensures that the arc is stable at different heights of the curved surface, so as to realize automatic surfacing welding of workpieces with complex curved surfaces, which specifically includes the following steps:

Step 1: Divide the sampling interval and determine the direction signal, and collect the welding current signal at the reference position

The magnetically controlled rotating arc sensor is installed on the welding torch, and an optical code disc with 64 mark points is installed on the motor shaft that drives the magnetic pole to rotate. According to the magnetic field to control the movement law of the arc, the directional interval sensor divides a sampling period into 8 sampling intervals and 8 interval directions, and set every two adjacent intervals as a sampling group, each sampling group is a direction signal, and the position of the signal is in the middle of the two intervals. Set 8 optocouplers to locate the 8 direction signals. When the repair work starts, the welding current signal of one or more sampling periods is collected at the flat position of the surface as reference data. After data processing, the average current of the reference period and the standard deviation of the average current of the sampling interval are determined as the subsequent welding current. Standard reference data for signal processing.

Step 2: Determine the high and low position of the welding torch according to the average current signal of the reference cycle

The position compensation controller analogizes the average current value of the reference sampling period according to the average current value of the sampling period received in each sampling period. Under the condition that the dry elongation of the welding wire remains unchanged, it calculates and processes according to the classic formula of the arc length of the rotating arc and the current, and converts The equivalent arc length difference is used to control the height of the welding torch to prevent large changes in the level of the curved surface, such as arc breakage when the curved surface is concave and gun collision when the curved surface is convex, to ensure the stability of the welding arc during the automatic surfacing welding process sex.

Step 3: Determine the welding direction according to the welding arc signals of different sampling groups in the current sampling period

The Hall sensor collects the average welding current value of different sampling intervals in the current sampling period, and adopts the interval variance analysis method. When the average current variance of the current sampling period is calculated to be greater than the average current variance of the reference period, the sampling group with the smallest average welding current value is determined. Locate the direction signal corresponding to the interval of this sampling group, according to the corresponding formula of welding current and arc length, determine that this direction is towards the position with a lower surface level, and drive the four-axis linkage welding machine to control the welding torch to perform welding sampling in the next cycle along this direction , to ensure that the welding direction is always towards the lower level of the surface; only when the variance of the average current value in each interval of the sampling period is less than or equal to the average current variance of the reference interval, the surface is considered to be approximately flat at this time. As the welding sampling is always carried out in the concave direction of the curved surface, the uneven position of the curved surface is always compensated, and the curved surface in a certain range tends to be flat, and the subsequent cycle of this process is repeated until the complex curved surface is completely flattened.

The beneficial effects of the present invention are: to propose a method of self-seeking complex curved surface surfacing welding based on magnetron rotating arc sensing, the method detects the uneven position of the curved surface through the signal of welding itself, and continuously fills the unevenness of the complex curved surface, Finally, the complete surfacing welding of the entire curved surface is achieved; the signal of the welding arc itself is adopted, the real-time performance is good, multiple sensors work in coordination, the system stability is high, and the process is highly intelligent, which solves the problem of low automation of complex surface surfacing welding. Problems such as low production efficiency, general surfacing quality and high labor costs have laid the foundation for the development of automated surfacing technology.

Description of drawings

Figure 1 is a block diagram of the automatic surfacing system

Figure 2 is a flow chart of the automatic surfacing welding process

Figure 3 is a schematic diagram of the working principle of the directional zone sensor

Figure 4 is a diagram of the system motion model

Implementation case

In order to better express the technical solutions and beneficial effects of the entire invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. However, the embodiments of the present invention are not limited thereto.

Embodiment 1 The present invention's self-seeking complex curved surface surfacing method based on magnetron rotating arc sensor is shown in Fig. Linkage welding machine; the working principle of the directional interval sensor is shown in Figure 3. One rotation sampling cycle is divided into 8 sampling intervals and 8 interval directions, and each adjacent two intervals are set as a sampling group. Each sampling The group is a direction signal whose position is in the middle of the two intervals. Eight optocouplers are installed on the optical code disc to locate each direction signal; in the workflow shown in Figure 2, when starting to work, the magnetron arc sensor first collects the welding current signal of the reference period, and the operation controller calculates the corresponding Interval average current, the four-axis linkage welding machine controls the welding torch to always weld along the direction where the average current of the sampling group is smaller, that is, the direction where the surface level is lower, until the average current in each interval fluctuates very little. At this time, the surface of the current area is approximately flat. If If there are other areas of the surface, continue the welding sampling process; as shown in Figure 4, the surface morphology of the surface is changed in a certain range by continuously filling the unevenness of the surface, and finally the entire surface is completely flattened, and the position compensation controller can Ensure the stability of the arc at different heights of the curved surface so as to realize automatic surfacing welding under complex curved surface conditions.

The specific implementation steps of the self-seeking complex curved surface surfacing welding method based on the magnetron rotating arc sensor in the present invention are as follows:

Step 1: Divide the sampling interval and determine the direction signal, and collect the welding current signal at the reference position

As shown in Figure 3: The magnetically controlled rotating arc sensor is installed on the welding torch, and an optical code disc with 64 mark points is installed on the motor shaft that drives the magnetic pole to rotate. The cycle is divided into 8 sampling intervals such as a, b, c, d, e, f, g, and h. In a single cycle, the average current for the area If x takes the value a:h, it can be expressed as:

Where: c is the number of data in a sampling period; n is the number of rotation cycles of the magnetic pole; s=c/8.

At the same time, set every two adjacent intervals as a sampling group, each sampling group is a direction signal, and the position of the signal is in the middle of the two intervals, and set 8 optocouplers to locate the direction signals of 1-8. The average welding current for each sampling group is It can be seen that:

The sampling data of the reference period is exactly 8 sampling data when n=0, and the average welding current average value of the reference period is represented by I ₀ ,

Step 2: Determine the high and low position of the welding torch according to the average current signal of the reference cycle

As shown in Figure 4, the sampling period is firstly taken at the flat position of the curved surface, and the position compensation controller compares the average current value of each sampling period with the average current value of the reference sampling period. Rotating arc GMAW welding system arc length and current classical formula calculation processing,

In the formula: v _n represents the rate of current change in the sampling period

Converted into the equivalent arc length difference e=L _n -L ₀ , it is used to control the height of the welding torch, so as to prevent the torch from colliding when the level of the curved surface changes greatly, such as when the curved surface is concave and the arc is broken, and the curved surface is convex. Stability of the welding arc during automatic overlay welding.

Step 3: Determine the welding direction according to the welding arc signals of different sampling groups in the current sampling period

The Hall sensor collects the average welding current value of different sampling intervals in the current sampling period, and the operation controller adopts the interval variance analysis method to express the average current in a single sampling period as In, and the average current _variance D(In) can _be expressed as:

When the variance of the average current value in the sampling interval is greater than the average current variance of the reference period, that is, D(I _n )>D(I ₀ ), determine 8 sampling groups The minimum value, get the direction signal corresponding to the sampling group with the minimum average current. According to the corresponding formula of welding current and arc length, it is determined that this direction is towards the lower level of the curved surface, and the four-axis linkage welding machine is driven to control the welding torch to go down in this direction. A period of welding sampling ensures that the welding is always at the lower level of the surface; only when the calculated variance of the average current value of each interval is less than or equal to the average current variance of the reference interval, that is, D(I _n )≤D(I ₀ ), It is determined that the curved surface is similar to a flat surface at this time, and sampling is carried out while welding during the whole process. As the welding is always carried out towards the lower level of the curved surface, the uneven position of the curved surface is always compensated, and the curved surface in a certain range tends to be flat. This process is repeated until the complex The curved surface is fully welded and smoothed.

Embodiment 2 The present invention is also applicable to the automatic processing of surfacing coatings on workpieces with complex shapes.

The above descriptions are only preferred implementations of the present invention, and it should be pointed out that any improvements made without departing from the principles of the present invention are considered within the protection scope of the present invention.

Claims (4)

1. The method of self-seeking complex curved surface surfacing welding based on magnetron rotating arc sensor is used for automatic surfacing welding of complex curved surface workpieces. Arithmetic controller, position compensation controller, four-axis linkage welding machine; this method divides the sampling interval and position direction through the directional interval sensor, the magnetic control rotating arc sensor collects the welding current, and the arithmetic controller calculates the average current of the corresponding interval in each direction. The four-axis linkage welding machine controls the welding torch to always weld along the direction where the average current is small, that is, the horizontal height of the curved surface is low. The position compensation controller ensures that the arc is stable at different heights of the curved surface, until the fluctuation of the average current in each interval is small, and the surfacing welding of the curved surface Finish. 2. According to claim 1, the self-seeking complex curved surface surfacing method based on magnetron rotating arc sensing is characterized in that: the direction-separating interval sensor includes a direction positioning module composed of an optical code disc and 8 optocouplers, a data The sampling and signal processing module is composed, and the sampling period is divided into 8 sampling intervals and 8 interval directions through the direction positioning module. Every two adjacent intervals are regarded as a sampling group, and each sampling group corresponds to a direction signal, and this direction is the welding torch direction of movement. 3. The method for overlaying complex curved surfaces based on magnetron rotating arc sensing according to claim 1, characterized in that: the average current value of each sampling cycle is compared with the average current value of the reference sampling cycle, according to the rotating arc The arc length and current are calculated and processed by the classic formula, which is converted into the equivalent arc length difference to control the height of the welding torch, prevent arc breaks at the concave surface of the curved surface and collision with the torch at the convex surface of the curved surface, so as to ensure the stability of the welding arc during the automatic surfacing welding process sex. 4. According to claim 1, the method of self-seeking complex curved surface welding based on magnetron rotating arc sensor is characterized in that: when the sampling starts, a cycle of welding current signal is first sampled at the flat position of the curved surface as a reference cycle, and passed The Hall sensor receives the welding current signal in the sampling interval, and the arithmetic controller calculates the average current value of each interval after filtering. Using the interval variance analysis method, when the average current variance of each interval in the sampling cycle is greater than the average current variance in the reference interval , compare and select the direction corresponding to the sampling group with the smallest average current, and according to the corresponding relationship of current arc length, it is determined that the level of the curved surface in this direction is low, and the four-axis linkage welding machine controls the welding torch to move forward according to the direction feedback of the directional interval controller; Fill the unevenness of the surface until the average current variance of the sampling period is less than or equal to the average current variance of the reference period interval, it is determined that the surface is close to a flat surface at this time, and the automatic surfacing welding under complex surface conditions is completed.