CN113894404B - Friction stir welding method based on photogrammetry - Google Patents

Abstract

The invention discloses a photogrammetry-based friction stir welding method, which belongs to the field of friction stir welding. The device used for welding includes friction stir welding equipment, photogrammetry equipment, and return light reflection mark points; the photogrammetry equipment and friction stir welding equipment are fixed , Paste the reflective mark point on the base metal to be welded; the specific welding method includes: equipment debugging, determining the welding seam track, setting the threshold, and welding. The invention has a simple and compact structure, is suitable for a wide range of plate thickness and plate width, high clamping efficiency, and low cost, and is especially suitable for complex working conditions such as trajectory planning of irregular welds and height differences between base metals on both sides of the weld. For various welding base materials, various friction stir welding equipment has strong adaptability.

Description

A Friction Stir Welding Method Based on Photogrammetry

technical field

The invention relates to the technical field of friction stir welding, in particular to a photogrammetry-based friction stir welding method.

Background technique

Friction stir welding technology is a high-quality solid-phase joining technology, which is widely used in splicing of aluminum alloy plates, welding of circumferential welds of aluminum alloy cylinders, welding of longitudinal welds of aluminum alloy cylinders and welding of large aluminum alloy structural parts . Friction stir welding technology mainly includes three technologies: stirring head structure design, effective process parameter planning and reasonable tooling structure design. Effective process parameter planning directly affects product welding quality, production efficiency and labor intensity, so effective process parameter planning is a key technology that restricts the further development of this technology, and it is also the most critical step that affects weld quality.

The application number is 201811169627.4, and the Chinese patent titled "A Tracking Device for Controlling the Penetration Depth of Friction Stir Welding Welding Head" has designed a device that can dynamically adjust the penetration depth according to the change of plate thickness. The equipment designed by this invention has a complex structure and high cost, and the invention cannot plan the weld trajectory and cannot adapt to the welding conditions where the thickness of the base metal on both sides is different. The function of adjusting the feeding speed of the stirring head according to the amplitude of the piercing process.

The application number is 202110087412.4, and the Chinese patent titled "Automatic Weld Tracking Method Based on Visual Sensing Based on Line Drawing Method" designs a prefabricated straight line parallel to the weld to plan the weld trajectory. This method does not have the function of dynamically adjusting the pressure depth according to the height difference between the two sides of the base metal to be welded. The accuracy of trajectory planning depends entirely on the accuracy of the prefabricated line, and the production is difficult.

It can be seen that when the special equipment for friction stir welding is used to weld the base metal, it is necessary to reduce the process and process equipment required for the base metal to be welded in order to better adapt to various welding conditions.

Contents of the invention

The object of the present invention is to provide a method of friction stir welding based on photogrammetry to solve the above-mentioned problems in the prior art.

In order to achieve the above object, the present invention provides the following scheme: the present invention provides a method of friction stir welding based on photogrammetry, and the devices used for welding include friction stir welding equipment, photogrammetry equipment, and return light reflection mark points;

The specific welding method includes the following steps:

For equipment debugging, the photogrammetry equipment is fixed on the friction stir welding equipment, and the light reflection mark points are pasted on the base material area outside the shoulder of the stirring head on both sides of the weld;

Determining the trajectory of the welding seam, using the friction stir welding equipment to manually teach the two-dimensional trajectory of the welding seam trajectory to the photogrammetry equipment;

Setting the threshold, inputting into the photogrammetry equipment the adjustment threshold of the feed speed, the adjustment threshold of the penetration depth and the adjustment threshold of the welding trajectory;

Do the welding.

Preferably, when the welding is performed, the welding process is divided into: the stage of inserting the stirring head, the stage of adjusting the shoulder of the stirring head, and the trajectory planning.

Preferably, in the stage of inserting the stirring head, the RMS value during the measurement process is fed back in real time by the photogrammetry equipment using photogrammetry technology, and the RMS value is compared with the adjustment threshold value of the inserting feed speed to determine Stirring head pressing speed, and adjust the stirring head pressing speed.

Preferably, in the stage of adjusting the shoulder of the stirring head, the distance between the shoulder of the stirring head and the base material to be welded is determined by the photogrammetry equipment, and the obtained distance parameter is compared with the adjustment threshold of the penetration depth, the The photogrammetry equipment sends the obtained comparison results to the control system of the friction stir welding equipment, and the height of the shoulder of the stirring head is adjusted by the control system of the friction stir welding equipment.

Preferably, in the trajectory planning, the photogrammetry equipment will identify the spatial coordinate position and passing order of the reflective marker points pasted on the surface of the welded base material during the manual teaching process, and the photogrammetry equipment will identify The obtained welding trajectory coordinates and the insertion amount of the stirring head are sent to the control system of the friction stir welding equipment, and the welding trajectory is corrected by the control system of the friction stir welding equipment.

Preferably, the retroreflective marker points are coded retroreflective marker points.

Preferably, the device used for welding further includes a reference ruler, the reference ruler is fixed with the friction stir welding equipment, and the reference ruler is located in the field of view of the photogrammetry equipment at the starting position of welding.

Preferably, the number of photogrammetry devices is not less than two.

Compared with the prior art, the present invention discloses the following technical effects:

First, the present invention is simple and compact in structure, applicable to a wide range of plate lengths and widths, easy to install, high in process planning efficiency, reliable and practical, and low in cost, and can meet the technical requirements of single shoulder and double shoulder friction stir welding.

Second, the present invention can solve the defect that the performance of the weld seam near the starting point of friction stir welding is weaker than that in the middle position, increase the usable length of the entire weld seam, save the processing amount of the weld seam with poor performance, and save materials and subsequent process time.

Third, the present invention is compatible with various welding conditions and process equipment, not only can be used for welding conditions of unequal thickness of the base metal to be welded and complex two-dimensional and three-dimensional welds; it can also be used for machine tool friction stir welding equipment, single Mechanical arm friction stir welding equipment and double mechanical arm cooperative or non-cooperative welding measuring arm.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is that the present invention is applied to the schematic diagram of machine tool class equipment;

Fig. 2 is a schematic diagram of the present invention applied to stand-alone friction stir welding equipment;

Fig. 3 is a schematic diagram of the application of the present invention to dual robotic arm equipment;

Among them, 1-machine tool type friction stir welding equipment; 2-photogrammetry equipment; 3-reference ruler; 4-light reflection point group; 5-single-arm friction stir welding equipment; 6-coordinated welding measuring arm.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The present invention provides a method of friction stir welding based on photogrammetry. The device used for welding includes friction stir welding equipment, photogrammetry equipment 2, and return light reflection mark points;

The specific welding method includes the following steps:

For equipment debugging, fix the photogrammetry equipment 2 on the friction stir welding equipment. The number of photogrammetry equipment 2 is not less than two, and the reflective mark points are pasted on the base material area outside the shoulder of the stirring head on both sides of the weld; the first use , it is necessary to calibrate the external reference and internal reference of the photogrammetry equipment 2; the retroreflective marker points can be single, or can be distributed in any shape such as strips or blocks.

The photogrammetry equipment 2 and the friction stir welding equipment are fixed together, so that the photogrammetry equipment 2 and the friction stir welding equipment can vibrate at the same frequency and amplitude, and can more accurately identify the intensity of the stirring head vibration, and then adjust the insertion of the stirring head Feed speed; and can more accurately identify the relative position of the shaft shoulder of the stirring head and the base metal to be welded, and make the shaft shoulder of the stirring head reach the preset pressure depth through an algorithm, so as to prevent vibration caused by insufficient rigidity of the equipment and other reasons, causing shaft Deep pulsation of shoulder pressure; it can also more effectively reduce the height difference of fish scales after welding, making the surface after welding smoother, denser and less post-welding processing.

Determine the welding seam trajectory, and use the friction stir welding equipment to manually teach the two-dimensional trajectory of the welding seam trajectory to the photogrammetry equipment 2;

Set the threshold, enter the adjustment threshold of the penetration feed speed, the adjustment threshold of the penetration depth and the adjustment threshold of the welding trajectory in the photogrammetry equipment 2;

The range of the adjustment threshold for the penetration feed speed is 0 to 100, the adjustment threshold for the penetration depth is -10 to +10, and the adjustment threshold for the welding trajectory is -10 to 10. The adjustment threshold of the piercing feed speed is responsible for adjusting the piercing speed. The piercing speed is related to the hardness of the metal material to be welded. The material with low hardness can use a larger threshold, and the material with high hardness can use a small threshold; through the piercing feed speed The threshold adjusts the process characteristics of the initial welding position of the friction stir welding; the penetration depth adjusts the threshold to control the penetration depth of the stirring head, and the positive threshold will make the stirring head penetrate deeper, so that the contact force between the shaft shoulder of the stirring head and the workpiece is greater, and the negative threshold is the opposite. The adjustment threshold of the penetration depth affects the forging force in the friction stir welding process, and the greater the threshold, the greater the forging force. The welding trajectory adjustment threshold is responsible for adjusting the allowable offset range between the trajectory detected by the camera equipment and the planned trajectory. The trajectory adjustment threshold is negative, biasing to the left, and biasing to the right when it is positive. The influence of welding track adjustment threshold can adjust the offset process parameters when the tool setting is inaccurate, so as to make the welding track more accurate.

Finally, it is enough to start the friction stir welding equipment. During the welding process, the photogrammetry equipment 2 will compare the deviation between the actual position of the stirring head and the set position in real time, and will adjust in real time when the above adjustment threshold is exceeded.

When welding, the welding process is divided into: the stirring head plunges into the stage, the stirring head shoulder adjustment stage, and trajectory planning.

In the stage of inserting the stirring head, the RMS value during the measurement process is fed back in real time by photogrammetry equipment 2 using photogrammetry technology, and the RMS value is compared with the threshold value of the feed speed adjustment to determine the pressing speed of the stirring head and adjust the speed of the stirring head. The pressing speed is adjusted.

If the RMS value exceeds the set value to the adjustment threshold of the feed speed during the stirring head insertion process, it means that the pressing speed of the stirring head is too high, and the base metal to be welded is not hot enough, then gradually reduce the downward pressing speed of the stirring head. Give the speed so that the difference between the RMS value and the set value is less than the adjustment threshold of the plunger feed speed; if the RMS value is less than the set value during the pressing of the shoulder, the amount is greater than the threshold value of the plunger feed speed adjustment, indicating that the stirring head is under If the pressing speed is too small, the base metal to be welded will be overheated. It is necessary to gradually increase the pressing feed speed of the stirring head until the difference between the RMS value and the set value is less than the adjustment threshold of the piercing feed speed.

In the stage of adjusting the shoulder of the stirring head, the distance between the shoulder of the stirring head and the base metal to be welded is determined by the photogrammetry device 2, and the obtained distance parameter is compared with the adjustment threshold of the penetration depth, and the photogrammetry device 2 sends the obtained comparison result to For the control system of the friction stir welding equipment, the height of the shoulder of the stirring head is adjusted by the control system of the friction stir welding equipment.

When the distance between the shoulder of the stirring head and the base material to be welded is greater than the adjustment threshold, the photogrammetry system of the photogrammetry device 2 sends an instruction to gradually press down the shoulder to the control system of the friction stir welding equipment; When the distance of the material is less than the adjustment threshold, the photogrammetry system sends an instruction to the control system of the friction stir welding equipment to gradually increase the shoulder; when the distance between the stirring head shoulder and the base metal to be welded fluctuates within the adjustment threshold, the photogrammetry system Send instructions.

Trajectory planning, through the photogrammetry equipment 2 to identify the spatial coordinate position and passing order of the coded return light reflection mark points pasted on the surface of the welded base metal during the manual teaching process, the photogrammetry equipment 2 will identify the welding trajectory coordinates and the stirring head The penetration amount is sent to the control system of the friction stir welding equipment, and the welding track is corrected by the control system of the friction stir welding equipment.

During the welding process, when the position of the welding fixture or the welding base material is changed due to heat, force or other disturbances, the photogrammetry system can also correct the welding trajectory, so that the equipment can complete the welding process according to the actual weld position.

When the number of photogrammetry equipment 2 is one, the device used for welding also includes a reference ruler 3, which is fixed with the friction stir welding equipment, and the reference ruler 3 is located in the field of view of the photogrammetry equipment 2 at the starting position of welding.

When using dual photogrammetry equipment 2 or multiple photogrammetry equipment 2, it is not necessary to use the reference ruler 3, and if the use of dual photogrammetry equipment 2 or multiple photogrammetry equipment 2 cannot guarantee a certain relative position, the reference ruler 3 needs to be used.

The friction stir welding equipment can be a machine tool friction stir welding equipment, or a single-arm or multi-arm mechanical arm friction stir welding equipment. The multi-arm friction stir welding mechanical arms can move cooperatively or independently. When the single-arm friction stir welding equipment and the cooperative welding measuring arm 6 are mounted with the photogrammetry equipment 2 at the same time, the reference ruler 3 is not needed.

Utilizing the friction stir welding method based on photogrammetry provided by the present invention can simplify the scale of equipment, greatly reduce the manufacturing cost and difficulty of manufacturing special equipment for friction stir welding; the welding process planning efficiency is high, and the welding phase measurement process and complexity are saved. The trajectory planning time of the weld seam.

In describing the present invention, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientations or positional relationships indicated by "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention, rather than indicating or It should not be construed as limiting the invention by implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation.

The above-mentioned embodiments are only to describe the preferred mode of the present invention, not to limit the scope of the present invention. Without departing from the design spirit of the present invention, those skilled in the art may make various Variations and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (4)

1. A kind of friction stir welding method based on photogrammetry, it is characterized in that, the device used for welding comprises friction stir welding equipment, photogrammetry equipment, return light reflection mark point; When carrying out described welding, welding process is divided into: stirring The head plunge stage, the stirring head shaft shoulder adjustment stage, and trajectory planning; the trajectory planning is to identify the spatial coordinates of the reflective marker points pasted on the surface of the welding base material during the manual teaching process through the photogrammetry equipment position and passing sequence, the photogrammetry equipment sends the identified welding trajectory coordinates and the amount of the stirring head penetration to the control system of the friction stir welding equipment, and corrects the welding trajectory through the control system of the friction stir welding equipment The reflective mark point of the return light is a coded reflective mark point of the return light; the device used for welding also includes a reference ruler, the reference ruler is fixed with the friction stir welding equipment, and when the reference ruler is located at the starting position of welding in the field of view of the photogrammetric device; The specific welding method includes the following steps: For equipment debugging, the photogrammetry equipment is fixed on the friction stir welding equipment, and the light reflection mark points are pasted on the base material area outside the shoulder of the stirring head on both sides of the weld; Determining the seam trajectory, the photogrammetry equipment uses the two-dimensional trajectory of the welding seam trajectory of the friction stir welding equipment to perform manual teaching; Setting the threshold, inputting into the photogrammetry equipment the adjustment threshold of the feed speed, the adjustment threshold of the penetration depth and the adjustment threshold of the welding trajectory; Do the welding. 2. The friction stir welding method based on photogrammetry according to claim 1, characterized in that, the stirring head plunges into the stage, and the photogrammetry equipment utilizes photogrammetry technology to feed back the RMS value in the measurement process in real time, and The RMS value is compared with the adjustment threshold of the piercing feed speed to determine the pressing speed of the stirring head, and adjust the pressing speed of the stirring head. 3. The friction stir welding method based on photogrammetry according to claim 1, characterized in that, in the stage of adjusting the shoulder of the stirring head, the distance between the shoulder of the stirring head and the base material to be welded is determined by the photogrammetry equipment, And compare the obtained distance parameter with the adjustment threshold of the penetration depth, the photogrammetry equipment sends the comparison result obtained to the control system of the friction stir welding equipment, and the control system of the friction stir welding equipment is used to control The height of the stirring head shoulder can be adjusted. 4. The photogrammetry-based friction stir welding method according to claim 1, wherein the number of the photogrammetry devices is not less than two.

Images