Method of fusion joint

Abstract

To provide a method of fusion joint that joins different types of metal plates having a large difference in melting point with high rigidity force.SOLUTION: A method of fusion joint includes the steps of: providing a steel plate 50 with a taper hole 211 and a lead plate 51 having a melting point that is lower than that of the steel plate 50, where the taper hole 211 is a hole of which diameter increases toward a non-contact surface from a contact surface where the steel plate 50 and the lead plate 51 come into contact with each other at mutual surfaces; putting a metal piece 209 containing the same component as the lead plate 51 into the taper hole 211; and irradiating the taper hole 211 with a laser beam 225 to fuse and solidify the metal piece 209, thereby joining the lead plate 51 to the steel plate 50 via the taper hole 211.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a fusion joining method for fusion joining different types of metal plates with a large difference in melting point to increase the strength of the joint. [Background technology]

[0002] Generally, lead plates are used to shield radiation, but because the lead plate itself is soft, it needs support from a steel plate or the like to stand on its own. Conventionally, the rigidity of the lead plate is ensured by bonding the steel plate and the lead plate together. Recently, instead of bonding using adhesives, a method of joining by frictional melting has been devised in which, by utilizing the difference in melting point of the lead plate, which has a lower melting point than the steel plate, when the steel plate and the lead plate are in contact with each other's surfaces, a joining tool part is pressed against the joint that joins the steel plate and the lead plate while rotating, so that the steel plate is heated by friction and the lead plate melts by thermal conduction, and the molten liquid flows into the joint and solidifies to join the steel plate and the lead plate (see, for example, Patent Document 1).

[0003] This frictional melting joining method has the advantage that it is easier to assemble and disassemble than adhesive bonding methods. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-32887 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional techniques can join different metal plates having widely different melting points, but in practice, higher rigidity, such as higher tensile strength, is required.

[0006] This embodiment has been proposed to solve the problems of the conventional technology as described above. The object of this embodiment is to provide a fusion joining method for joining different types of metal plates having a large difference in melting point with high rigidity. [Means for solving the problem]

[0007] In order to achieve the above object, the invention described in claim 1 comprises a first metal plate having a tapered hole, a second metal plate having a melting point lower than that of the first metal plate, the tapered hole being a hole whose diameter increases from a contact surface where the first metal plate and the second metal plate are in contact with each other toward a non-contact surface, and a metal piece containing the same components as the second metal plate is inserted into the tapered hole, and laser light is irradiated into the tapered hole to melt and solidify the metal piece, thereby joining the first metal plate and the second metal plate via the second metal plate and the tapered hole.

[0008] In order to achieve the above-mentioned object, the invention described in claim 2 is characterized in that, in the fusion joining method described in claim 1, laser light is irradiated toward the surface of the tapered hole, and the metal pieces are melted by also utilizing the reflected light of the laser light generated by the surface of the tapered hole.

[0009] In order to achieve the above-mentioned object, the invention described in claim 3 is characterized in that, in the fusion joining method described in claim 2, the intensity and beam diameter of the laser light and the speed at which the laser light scans the tapered hole are set so that the temperatures of the metal piece, the second metal plate, and the first metal plate exceed their respective melting points and are below their respective boiling points.

[0010] In order to achieve the above object, the invention as recited in claim 4 is characterized in that in the fusion joining method as recited in claim 1, the surface of the tapered hole has an uneven portion.

[0011] In order to achieve the above object, the invention described in claim 5 is characterized in that, in the fusion joining method described in claim 1, the first metal plate is a steel plate and the second metal plate is a lead plate, thereby increasing the radiation attenuation coefficient for X-rays and gamma rays.

[0012] In order to achieve the above object, the invention as recited in claim 6 is characterized in that, in the fusion joining method as recited in claim 5, the metal pieces are made of a lead alloy containing antimony. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of an embodiment of the present invention. [Diagram 2] This is a cross-sectional view of the start of the supply of metal pieces for fusion joining one steel plate and one lead plate. [Diagram 3] This is a cross-sectional view of the start of the supply of metal pieces to perform fusion joining of one lead plate sandwiched between two steel plates. [Figure 4] FIG. 11 is a cross-sectional view showing the completion of supply of metal pieces. [Diagram 5] This is a perspective view of the fiber laser light from the fiber nozzle when the galvanometer scanner starts. [Figure 6] FIG. 2 is an enlarged perspective view of the mechanism of a galvano scanner of fiber laser light. [Figure 7] 1 is a schematic diagram of a tapered surface of a tapered hole in a steel plate irradiated with fiber laser light. FIG. [Figure 8] This is a diagram of the molten layer between the steel plate and the lead plate. [Figure 9] This is a perspective view of the raised, solidified state of a lead plate before it is flattened using a belt grinding machine. [Figure 10] This is an oblique view of the finished product after the raised, solidified state of the lead plate has been flattened using a belt grinding machine. [Figure 11] This is a diagram showing how steel plates and lead plates are separated and dismantled using a cutting drill. [Figure 12] FIG. 1 is a comparison diagram of tensile tests of friction melt joining and laser melt joining of steel and lead plates. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (Configuration of the embodiment) Hereinafter, the configuration of the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a fusion joining apparatus 200 which is an apparatus for realizing a fusion joining method. FIG. 2 is a cross-sectional view showing the start of supplying a metal piece 209 containing the same components as a lead plate 51 in order to fusion-join a steel plate 50 (first metal plate) and a lead plate 51 (second metal plate). The fusion joining apparatus 200 is for manufacturing a radiation inspection room or panel for storing a radiation source or the like, and in order to fix the lead plate 51 which can increase the radiation attenuation coefficient and the steel plate 50 which supports it, the steel plate 50 and the lead plate 51 are fusion-joined by hooking a plurality of tapered holes 211 provided in the steel plate 50. By using the lead plate 51, the radiation attenuation coefficient for X-rays and gamma rays can be increased.

[0015] FIG. 3 shows a method for producing a fusion-jointed panel using a total of three metal plates, with two steel plates 50 and a lead plate 51 sandwiched between them.

[0016] The method in FIG. 2 is used when the lead plate 51 is relatively thin and it has been confirmed through calculation and experience that there will be no problems with it falling when used on the ceiling or wall of a radiology examination room. The method in FIG. 3 is used when the lead plate 51 is thick and heavy and when used on the ceiling or wall of a radiology examination room, it takes into consideration safety measures in the unlikely event that it peels off or falls.

[0017] 2 and 3, in order to melt and join a steel plate 50 and a lead plate 51, a metal piece 209 is supplied to a tapered hole from a metal piece supplying machine 208, and a lead plate 51 cut to a required size is laid on the XY movable table 219 in Fig. 1. The steel plate 50 is placed on top of it so that a tapered hole 211 in the lead plate 51 becomes larger in diameter from the joining surface to the non-joining surface, and the lead plate 51 is fixed with a C-type vice or the like (not shown). This allows the metal piece 209 to be inserted into the tapered hole 211.

[0018] Fig. 4 is a cross-sectional view of the completion of supply of metal pieces 209 for fusion joining in the configuration of Fig. 1. Fig. 5 is a perspective view of the start of fiber laser light 225 from fiber laser nozzle 205 irradiated by a galvanometer scanner in order to perform fusion joining in the configuration of Fig. 1. As shown in Figs. 4 and 5, the start points of multiple tapered holes 211 in steel plate 50 are determined, and metal pieces 209 are supplied to multiple tapered holes 211 by moving XY movable table 219 and up / down / front / back movable telescopic arm 221. Then, fiber laser light 225 is irradiated from inside fiber laser nozzle 205, and the irradiated position is set to about half the depth of the inclined side surface of tapered hole 211.

[0019] The fiber laser light 225 in Figures 6 and 7 is irradiated onto the tapered hole 211 via a rotation mechanism of a galvanometer mirror X 227 and a galvanometer mirror Y 226 and a lens 228, and a scan area 220 of the fiber laser light 255 is secured for a plurality of tapered holes 211 as shown in Figure 7.

[0020] FIG. 8 is a diagram showing the melting process of steel plate 50 and lead plate 51, with the vertical axis indicating temperature and the horizontal axis indicating time. The shaded areas are melting layer diagrams of the melting point (1536°C) and boiling point (2863°C) of steel plate 50 and the melting point (327°C) and boiling point (1750°C) of lead plate 51.

[0021] FIG. 9 is a diagram showing the state in which the steel plate 50 and the lead plate 51 are fused together by using the tapered holes 211 formed in the steel plate 50 as hooks, with the tapered hole 211 portion raised, and is a diagram showing the state before grinding with the belt grinding machine 207.

[0022] FIG. 10 is a diagram showing a state 224 in which a bulge 223 formed after melting in a tapered hole 211 of a steel plate 50 has been ground by a belt grinding machine 207 .

[0023] FIG. 11 is a diagram showing how the steel plate 50 and the lead plate 51 are separated and dismantled by a cutting drill 229. When a radiation shielding box becomes unnecessary and is to be discarded, it is necessary to separate and dismantle the lead plate of the radiation shielding box. Until now, a professional company was required to separate and dismantle the steel plate and the lead plate by prying open the adhesive between the steel plate and the lead plate with a tool or by applying fire to melt the lead. According to this embodiment, this can be easily done by cutting the molten joint part of the tapered hole 211 of the steel plate 50 with a cutting drill 229 to cut the lead plate 51, although cutting chips 230 will be produced.

[0024] In summary, the embodiment of the present invention has the following configuration.

[0025] (1) The laser oscillator 201 is provided for emitting fiber laser light 225.

[0026] (2) A control device 202 is provided for controlling the power supply, control system, cooling unit, etc. of the fiber laser light 225.

[0027] (3) Place the lead plate 51 on the XY movable table 219, place the steel plate 50 on top of that, and after confirming that there is no misalignment, a clamp (not shown) or the like is provided to prevent the steel plate 50 and the lead plate 51 from moving.

[0028] (4) A metal piece feeder 208 is provided to feed the material of the metal piece 209 (hard lead = pure lead + 4 to 6% antimony) to the tapered hole 211. By including antimony, the strength of the metal piece 209 increases when the metal piece 209 solidifies due to melting and joining the lead plate 51.

[0029] (5) A belt grinding machine 207 is provided for grinding the protruding portion of the metal piece 209 after melt joining to a flat surface.

[0030] (6) The belt grinding machine 207 is equipped with a belt grinding machine cover 203 and a dust vacuum 216 to prevent shavings from scattering during grinding.

[0031] (7) A telescopic arm 221 that moves up and down and back and forth is provided to optimize the irradiation position of the fiber laser light 225.

[0032] (8) Galvanometer mirrors 226 and 227 are provided so that when irradiating fiber laser light 225, the center position in tapered hole 211 can be changed to an optimal position by rotation.

[0033] (9) Near the fiber laser beam 225, there is provided an assist gas sprayer 210 which has the effect of quickly removing the molten material and evaporated gas generated by the fiber laser beam 225, blowing off the molten deposits, cooling the molten portion, and suppressing the expansion of the heat-affected area, and which also protects the lens of the focusing optical system of the fiber laser beam 225 from the molten material and flying material (spatter).

[0034] (10) Equipped with an interior observation camera 222 that allows the interior condition to be confirmed.

[0035] (11) The whole cover 214 for preventing damage caused by the fiber laser light 225 has an observation window from the outside and is fitted with a plate that blocks the fiber laser light 225 to protect the eyes. In addition, ducts 212a and 212b with dust suction fans are installed to prevent workers from inhaling dust coming out of the steel and lead plates.

[0036] (12) The operation panel 215 is provided with a monitor 217 on which an operator 218 can check the state of the fusion bonding apparatus 200 via the operation panel 215 .

[0037] (Operation of the embodiment) The operation of the fiber laser melt joining device of this embodiment is as follows.

[0038] The up-down and back-and-forth movable extendable arm 221 of the fusion bonding device 200, the fiber laser head 204, and the like are all placed on standby at the origin position of the XY movable table 219.

[0039] If the lead plate 51 is lightweight, a combination of one steel plate 50 and one lead plate 51 is also similarly arranged so that when the steel plate 50 and the lead plate 51 are brought into contact with each other's faces, the diameter of the tapered hole 211 increases from the contact surface toward the non-contact surface, and the plates are set on the XY movable table 219 and fixed with a C-clamp or the like.

[0040] If the lead plate 51 is thick or heavy, it is sandwiched between two steel plates 50, and the steel plate 50 and the lead plate 51 are set on an XY movable table 219 so that the diameter of the tapered hole 211 increases from the contact surface toward the non-contact surface when the steel plate 50 and the lead plate 51 are in contact with each other, and then the plate is fixed with a C-clamp or the like (not shown). After completing the fusion joining of the steel plate 50 and the lead plate 51 on one side at the multiple tapered holes 211, the opposite side is also joined in the same manner.

[0041] A constant amount of metal pieces 209 is supplied from a metal piece supplying device 208 to a tapered hole 211 of a steel plate 50. Thereafter, a state in which a constant amount of metal pieces 209 has been supplied is confirmed by a sensor (not shown). It is preferable to supply enough metal pieces 209 to fill the tapered hole 211 so that it is heaped up.

[0042] The fiber laser head 204 moves toward the inclined portion of the tapered hole 211 of the steel plate 50 and irradiates the fiber laser light 225 from the fiber laser nozzle 205 under the following fiber laser irradiation conditions. Fiber laser light power: Approx. 600W Galvano scanner speed for tapered hole: 0.5mm / S Fiber laser irradiation diameter: φ2mm Fiber laser light galvanometer scanner Outer diameter: φ4mm

[0043] 6 shows the internal mechanism of the galvanometer mirror 206. To perform a galvanometer scanner on the circumference of the inclined portion of the tapered hole 211, the galvanometer mirror Y 226 and the galvanometer mirror X 227 are operated.

[0044] The molten layer diagram (shaded area) of steel plate 50 and lead plate 51 shown in Figure 8 shows the temperature axis vertically and the time axis horizontally, with fusion joining occurring near the melting point of steel plate 50 (1536°C) and near the boiling point of lead plate 51 (1750°C).

[0045] 9 and 10 show the steel plate 50 and the lead plate 51 fused together in the tapered hole 211, and the portion of the lead plate 51 where the solidified metal piece 209 rises in the tapered hole 211, before and after grinding in the belt grinding machine 207.

[0046] In summary, the embodiment of the present invention operates as follows.

[0047] (1) The lead plate 51 is placed on the XY movable table 219 using a lifter, crane, etc.

[0048] (2) The steel plate 50 has a plurality of tapered holes 211 machined on its upper surface, and is stacked so that the holes are oriented such that their diameter increases from the contact surface where the steel plate 50 and the lead plate 51 are in contact with each other toward the non-contact surface.

[0049] (3) After confirming that the steel plate 50 and the lead plate 51 on the XY movable table 219 are not misaligned, they are firmly fixed in place with a clamp (not shown) or the like to prevent movement.

[0050] (4) The metal pieces 209 are supplied from the metal piece supplying device 208 to the tapered hole 211. After the metal pieces 209 are irradiated with the fiber laser light 225, they cool and solidify, causing them to dent. Therefore, it is advisable to supply a certain amount of metal in advance in a heap.

[0051] (5) The fiber laser light 225 is irradiated by a galvanometer mirror scanner mechanism with a laser light intensity, beam diameter, and scanning speed of the tapered hole that are predetermined conditions, and the metal piece 209 and the lead plate 51 can be melted by making one revolution inside the tapered hole 211.

[0052] (6) The fiber laser light 225 is irradiated and adjusted so that the temperatures of the metal piece 209, the lead plate 51, and the steel plate 50 exceed their respective melting points and are below their respective boiling points.

[0053] (7) At this time, the steel plate 50 is near its melting point, but the metal piece 209 with a low melting point is above its melting point, and while it is in a state close to boiling, the steel plate 50 and the lead plate 51 are in a molten and joined state. Therefore, it is advisable to select the first metal plate and the second metal plate that have a temperature range from the melting point to the boiling point that overlaps in part. The lead plate 51 is first irradiated with the fiber laser light 225, and instantaneously reaches its melting point of 327.5°C. The fiber laser light 225 rotates once while reflecting at a reflectance rate of about 55% at the tapered hole 211. At this time, it reaches near the boiling point of the lead plate 51, 1750°C. The steel plate 50 reaches its melting point of 1536°C, and then it slightly exceeds its melting point, and the metal piece 209 and the lead plate 51 flow into and penetrate the unevenness of the processed surface of the tapered hole 211 of the steel plate 50, and are in a molten and joined state.

[0054] In order to keep the temperature of the spot irradiated with the fiber laser light 225 within a predetermined temperature range, it is possible to monitor the temperature with an infrared thermometer or the like, and automatically control at least one of the intensity and beam diameter of the fiber laser light 225, and the speed at which the fiber laser light 225 scans the tapered hole 211.

[0055] (8) After the fusion joining of the steel plate 50 and the lead plate 51 is completed, the raised portion of the tapered hole 211 of the steel plate 50 is ground down by the belt grinding machine 207 using the XY movable table 219 to make it flat to the same height as the surrounding area. This makes it possible to create an inconspicuous and beautiful appearance after painting.

[0056] (9) Repeat the above steps.

[0057] (Effects of the embodiment) This embodiment has the following advantages.

[0058] (Tensile test comparison results) 12 is a graph showing comparative results of a tensile test when a steel plate 50 and a lead plate 51 are joined by a conventional friction fusion joining method and the fusion joining method of this embodiment. As can be seen from this graph, the fusion joining method of this embodiment can obtain a tensile strength about three times that of the conventional method.

[0059] In addition, when the working time required to join the steel plate 50 and the lead plate 51 is compared between the conventional friction fusion joining method and the fusion joining method of this embodiment, the fusion joining method of this embodiment can reduce the working time by about 1 / 25.

[0060] The unnecessary steel plate 50 and lead plate 51 can be separated and dismantled simply by machining the tapered hole 211 of the steel plate 50 with a cutting drill 229, and the work time can also be shortened.

[0061] When the steel plate 50 and the lead plate 51 are separated and dismantled, the steel plate 50 and the lead plate 51 are unlikely to be seriously damaged, and therefore can be reused.

[0062] By using the fusion bonding method of this embodiment, it is possible to manufacture a radiology examination room.

[0063] The overall finish is smooth and there are no uneven areas, making for a beautiful painted surface when painted. [Explanation of symbols]

[0064] 50 steel plate 51 Lead plate 200 Fusion bonding equipment 201 Laser Oscillator 202 Control device 203 Belt grinding machine cover 204 Fiber laser head 205 Fiber laser nozzle 206 Galvano Mirror 207 Belt grinding machine 208 Metal piece feeder 209 Metal piece 210 Assist gas sprayer 211 Tapered hole 212a,b Duct with dust absorbing fan 213 Fiber laser processing machine 214 Total cover for preventing accidents 215 Operation Panel 216 Dust Vacuum 217 Monitor 218 Worker 219 XY movable table 220 Scan Area 221 Up / down / forward / backward movement telescopic arm 222 Interior Observation Camera 223 The state of the lead plate after melting 224 Completed grinding of lead plate after melting 225 Fiber laser light 226 Galvano Mirror Y 227 Galvano Mirror X 228 Lens 229 Cutting Drill 230 Lead plate chips

Claims

1. A first metal plate having a tapered hole; a second metal plate having a melting point lower than that of the first metal plate; The tapered hole is a hole whose diameter increases from the contact surface where the first metal plate and the second metal plate are in contact with each other toward the non-contact surface, and a metal piece containing the same components as the second metal plate is inserted into the tapered hole, and laser light is irradiated into the tapered hole to melt and solidify the metal piece, thereby joining the first metal plate and the second metal plate via the second metal plate and the tapered hole.

2. The fusion joining method according to claim 1 , further comprising irradiating a laser beam toward a surface of the tapered hole, and using reflected light of the laser beam generated by the surface of the tapered hole as well, to melt the metal pieces.

3. The fusion joining method according to claim 2, wherein the intensity, beam diameter and speed at which the laser light scans the tapered hole are set so that the temperatures of the metal piece, the second metal plate and the first metal plate exceed their respective melting points and are lower than their respective boiling points.

4. The fusion joining method according to claim 1 , wherein the surface of the tapered hole has an uneven portion.

5. 2. The fusion joining method according to claim 1, wherein the first metal plate is a steel plate and the second metal plate is a lead plate, thereby increasing the radiation attenuation coefficient for X-rays and gamma rays.

6. 6. The fusion joining method according to claim 5, wherein the metal pieces are made of a lead alloy containing antimony.

Images