Welding system with X-ray imaging of the weld
The welding system addresses the challenge of weld penetration depth and porosity detection by using X-ray cameras and data processors to control electron beams, ensuring precise imaging and real-time defect identification.
Patent Information
- Application Number
- JP2025517103
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-12-12
- Filing Date
- 2023-11-13
- Publication Date
- 2025-11-28
AI Technical Summary
Existing welding systems using high-energy sources face challenges in accurately determining the penetration depth and detecting defects such as porosity in welds due to issues with imaging resolution and defect identification during the welding process.
A welding system incorporating an evacuable welding chamber with an electron beam gun and detectors positioned at the front and rear of the joining interface, utilizing X-ray cameras to monitor weld penetration depth and porosity in real-time, with data processors controlling beam deflection and movement for precise imaging.
Enables real-time monitoring of weld penetration depth and porosity, allowing for immediate process adjustments and post-weld inspection triggers, enhancing weld quality and defect detection.
Smart Images
Figure 2025538338000001_ABST
Abstract
Description
[Technical Field]
[0001] FIELD OF THE INVENTION The present invention relates in particular to a welding system involving X-ray imaging of the weld to enable monitoring of the quality of the weld joint.
[0002] Background of the Invention When high-energy sources such as electron beams are used to weld joints, problems arise with weld quality during the welding process. The penetration depth of the weld can vary and can exhibit porosity within the cooled joint. Imaging of welds has been performed using x-ray sources that transmit x-rays through the completed weld, but problems arise with resolving the weld area and therefore determining the nature and extent of defects within the weld.
[0003] SUMMARY OF THE INVENTION According to the present invention, there is provided a welding system comprising an evacuable welding chamber, an electron beam gun connected to the welding chamber, at least one detector for acquiring X-ray images, and at least two bodies to be welded together, the bodies being adjacent along a joining interface defining a path along which the welding will occur, the joining interface having a front portion and a rear portion, the at least one detector comprising an input element positioned near the front portion of the joining interface to detect X-rays emitted during welding, thereby enabling easy detection of the image penetration depth of the weld joining the two bodies together.
[0004] Preferably, the electron beam gun generates an electron beam that travels along the connection interface from the rear portion to the front portion and thus towards the input element.
[0005] The at least one detector may comprise a photodiode or an array of sensing elements such as found in an X-ray camera.
[0006] The welding system may further comprise a second detector for acquiring X-ray images, the second detector comprising a second input element positioned near a rear portion of the connection interface, thus enabling imaging of porosity in the completed weld.
[0007] Preferably, the second detector comprises a photodiode or an array of sensing elements such as found in an X-ray camera.
[0008] The or each input element is preferably located within the welding chamber and may comprise a pinhole fiber optic input, or alternatively, the or each input element may be external to the welding chamber and adjacent an x-ray transparent window.
[0009] The or each detector may be connected to a data processor configured to affect the beam deflection system and thus control the properties and direction and speed of the electron beam produced by the electron beam gun.
[0010] The or each detector may be connected to a data processor configured to act on the controller to regulate the movement of the body during welding.
[0011] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]
[0012] [Figure 1] 1 is a schematic diagram of a welding system used to obtain an X-ray image of a weld joint. [Figure 2] FIG. 1 is a schematic diagram of a weld during acquisition of an X-ray image. [Figure 3] 1 is an exemplary X-ray image obtained by imaging from the front of a weld joint. [Figure 4] 1 is an exemplary X-ray image obtained by imaging from behind a weld joint. DETAILED DESCRIPTION OF THE INVENTION
[0013] explanation A schematic diagram of a welding system 10 having two parts or bodies 12, 14 to be welded together is shown in Figure 1, in which an electron beam gun 20 generates an electron beam 22 within a vacuum chamber 24. The beam 22 moves along a joining interface 26 between adjacent parts 12, 14, creating a keyhole weld having a width of approximately 300-600 µm. Typically, the beam 22 moves in a raster pattern, scanning across the interface 26 in a direction perpendicular to the direction of travel of the beam 22 along the interface 26.
[0014] A pinhole fiber optic input 30 located within the vacuum chamber 24 near the front end 31 of the interface 26 detects the x-rays generated by the electron beam 22 impinging on the materials 12, 14 being welded. The input 30 is connected to an image detector 36, such as a single photodiode, an array of sensing elements, or an x-ray camera, preferentially located outside the vacuum chamber 24.
[0015] The use of an optical fiber or other small pinhole-like input allows the input 30 to be placed close to the interface 26, and multiple switchable inputs can be used if necessary to ensure speed and ease of image acquisition. Optionally, an aperture shim can be positioned in front of the input 30 to provide protection from weld debris.
[0016] The X-ray camera 36 includes a high-speed scintillator and image acquisition electronics. X-ray images detected by the camera 36 generate image data, which are processed within a processor 42. The processed data from the processor 42 is passed to a deflection control system 44, which changes the direction and focus of the electron beam 22, moves the beam 22 along the interface 26, and controls the time of image acquisition by the camera 36. A motor encoder 46 and a CNC controller 48 are also connected to the processor 42 so that data can be transferred bidirectionally to provide active control of the movement of the bodies 12, 14 as needed during weld creation and image detection.
[0017] FIG. 2 shows parts 12, 14 in more detail. During welding, which typically occurs at a voltage of about 36-170 kV, electron beam 22 is controlled by system 44 to move in the direction of arrow 48 along a path defined by connection interface 26. Input 30 to x-ray camera 36 is positioned perpendicular to welding beam 22 and coincident with interface 26 to image along connection interface 26 where parts 12, 14 abut but have not yet been welded together. Beam 22 is shown traveling in the direction of arrow 48 from behind interface 26 toward a position where input 30 is positioned near leading edge 31. For flat, substantially two-dimensional parts, camera 36 is again positioned directly above the surface of the part, which is the imaging interface 26.
[0018] When the electron beam 22 strikes the parts 12, 14, it creates a melt pool 51 that solidifies to form a weld 32 joining the parts 12 and 14. X-rays 52, 52' are generated within and emitted from the melt pool 51 between the parts 12, 14. By positioning the input 30 near the leading end 31 at a location forward of the weld joint 32, an X-ray image can be obtained from the front of the weld joint 32. This produces an image 60, as shown in FIG. 3, which allows the penetration depth of the weld joint 32 to be measured and monitored. Detection of any changes in the weld penetration depth can be used to trigger a process alarm so that weld defects can be addressed. If necessary, the linear or motor position of the beam 22 along the joint 32 can be recorded when a process alarm is triggered, thus identifying areas that may require ultrasonic inspection after the weld is completed.
[0019] If desired, a second X-ray camera 36' with an associated input 30' can be positioned at a rear portion 61 of the interface 26 to image the completed weld. Referring to FIG. 4, where an upper spot 62 represents the weld location and a lower spot 64 indicates the presence of porosity in the weld, a portion of the X-rays generated from the molten pool 51 will travel through the completed weld 32 toward the input 30', thereby identifying areas of porosity in the completed weld. With X-rays generated near the area where the beam 22 is incident, the X-ray images generated as the beam 22 travels along the interface 26 provide a series of images along the length of the weld joint, allowing the entire length of the weld joint 32 to be imaged.
[0020] By using cameras behind and in front of the interface 26, both the penetration and porosity of the weld 32 can be actively monitored as it is being formed.
[0021] The resolution of the x-ray images is limited by the response time of the scintillators in the cameras 36, 36', with fast scintillators typically having a response time of less than 100 ns, thus allowing for a resolution of greater than 50 x 50 pixels. FPGA closed-loop image processing can be used to control the welding process, monitoring the acquired images to determine when the weld is complete and allowing monitoring of beam penetration at the weld site so that the welding beam power can be increased to achieve the required melting.
Claims
1. 1. A welding system comprising: an evacuable welding chamber; an electron beam gun connected to the welding chamber; at least one detector for acquiring X-ray images; and at least two bodies to be welded together, the bodies adjacent along a connection interface defining a path along which welding occurs, the connection interface having a forward portion and a rearward portion, the at least one detector comprising an input element positioned near the forward portion of the connection interface to detect X-rays emitted during welding.
2. The welding system of claim 1 , wherein the electron beam gun generates an electron beam that travels along the connection interface from the rear portion to the front portion.
3. The welding system of claim 1 or claim 2, wherein the at least one detector comprises an X-ray camera.
4. 10. The welding system of claim 1, further comprising a second detector for acquiring an X-ray image, the second detector comprising a second input element positioned near the rear portion of the connection interface.
5. The welding system of claim 4 , wherein the second detector comprises an x-ray camera.
6. 10. A welding system according to any preceding claim, wherein the or each input element is located within the welding chamber.
7. A welding system according to any preceding claim, wherein the or each input element is external to the welding chamber and adjacent an X-ray transparent window.
8. A welding system according to any one of claims 5 to 7, wherein the or each input element is a pinhole fibre optic input.
9. 10. A welding system according to any preceding claim, wherein the or each detector is connected to a data processor arranged to affect a beam deflection system.
10. 10. A welding system according to any preceding claim, wherein the or each detector is connected to a data processor arranged to act on a controller to regulate movement of the body during welding.