KR20030092553A - Method and Apparatus for Welding - Google Patents

Abstract

PURPOSE: A welding method and a welding apparatus are provided to improve productivity while reducing environmental contamination by reducing a volume of weld shielding gas and automatically operating the welding apparatus. CONSTITUTION: A welding apparatus includes a laser beam generator(20), a beam splitter(23), a focusing lens(40), and a cylinder(36). The laser beam generator(20) generates laser beam and is coupled to a laser supplying section(19) connected to a host computer(66). The beam splitter(23) is installed at the front of the laser beam generator(20) in such a manner that a route of laser beam is converted by means of scanning mirrors(38,39). The focusing lens(40) is installed on linear slider tables(25,26). The cylinder(36) securely fixes male and female films(41,,42) by using a vacuum cup(33).

Description

Welding Method and Apparatus {Method and Apparatus for Welding}

The present invention relates to a welding method and apparatus, in particular, in manufacturing a welded metal bellows, it is possible to increase the manufacturing throughput, and to reduce the volume of weld shielding gas consumed during the welding process. Welding method and apparatus for fabricating welded metal bellows to reduce contamination by automating the parts that operate the device, to reduce contamination, and to produce higher production rates without the need for skilled welders. will be.

In a conventionally known method for manufacturing a welded metal bellows, a large number of circular metal diaphragms are pressed to a thickness of 0.004 inch, and the male and female pairs are put into the clamping machine and then the clamp is closed.

The metal diaphragm introduced into the clamping machine as described above welded the inner diameter ID of the diaphragm using conventional welding methods such as TIG torch, plasma, electron beam, MIG, gas, and / or GTAW.

After mass welding the metal diaphragms together using the TIG or the like, the diaphragm is loaded on an axis between a copper heat dispersing ring and an end plate clamped to a clamping machine, and the metal diaphragm is loaded. Close contact with adjacent part and fix it. The clamping machine is then placed on the shelf and rotated at low speed under another TIG welding torch.

The welding operator adjusts the position of the welding torch so that the welding tip is close to the first seam of the two diaphragms, and then discharges an arc between the torch tip and the seam, carefully using a microscope. Welding is performed along the deviation of the seam path. By following the deviation of the seam path as described above, the welder can discharge the arc at the center of the diaphragm seam.

When welding is completed as described above, the TIG torch is moved to the next shim and the above process is continued and repeated to manufacture a welded metal bellows.

However, in the welding method as described above, a number of convolutions have to be made in order to produce one metal bellows, which increases the fatigue of the welding worker. In particular, in the case of using the above method, the welding speed varies according to the welder's skill, and the maximum welding speed of the skilled welder depends on the time required for manual adjustment during the welding procedure.

The welding speed of a typical metal diaphragm is typically 10 to 12 inches per minute when welding a pair of diaphragms with a thickness of 0.008 inches. Therefore, in the entire welding procedure from the first welding to the last welding, the time required for one skilled worker to weld may be 1 hour or more, and it may take a very long time when an unskilled or semi-skilled worker welds.

In most cases, the welder uses a microscope to monitor the welding process. During the welding process, a welding gas such as argon is injected directly into the welding part, and if the welder is exposed to the welding gas for a long time, there is a possibility of mild oxygen deficiency. Since the weld must be open so that the welder can access the weld, the weld gas continues to flow. Since the dimensions of the diaphragm are small, it is difficult to automate the welding process at an efficient cost, and thus it is difficult to maintain the robustness, integration, and reliability of the welding that can be obtained by a skilled welder.

Particularly, a case of manufacturing a welded bellows using a laser has been attempted, but the laser edge-welding method cannot obtain sufficient reliability or repeatability, and only a few prototypes are used. And the amount of laser welded bellows that could be produced experimentally could only be obtained.

The disadvantage of using the laser beam in such a bellows welding process is that the dimension of the laser beam is generally very small, and the output density of the laser beam is relatively high. In fact, high power densities of up to several Mwatts / cm ² are much hotter than any type of TIG torch that is currently used for this type of welding, and can instantly melt most materials in the focus range.

In conclusion, the welding fixture used for the laser welding method must be made 100% accurate.

However, deviations in the weld seam can be caused by minute vibrations in the machine, which can cause the weld seam to move from side to side as the bellows assembly rotates under the TIG torch. The passive method used when welding the bellows diaphragm requires a large amount of dependence on the technical skills of the welder when any deviation occurs in the welding seam, and therefore, the skill of a skilled welder is required to produce a high quality weldment.

In addition, the welder should inspect each weld bead when the welding is completed, thereby increasing the fatigue caused by the inspection, as well as using each microscope for each weld bead when the weld bead is moved from one welding station to another. By inspection. If a faulty weldment is used in the bellows assembly, there is a risk of failure during exercising, and air leaks due to incomplete welding, and thus there is a problem of discarding the completed bellows. .

In addition, another problem related to the above-described laser welding method is a spatial mode hopping phenomenon. In other words, when the laser is running, the profile of the laser beam output distribution shows that the laser beam is the hottest at the center. However, the adjustment of the laser resonator mirror or the variation of the pump power into the arc lamp changes the spatial distribution, so that the hottest part of the laser may appear to move in the cross section of the laser beam. Indeed, the spatial mode in high power laser systems changes often early or late in the welding process, since the laser power is programmed to increase or decrease. Along with the static beam, variations in the power density in the cross section of the beam are often reflected in the molten material of the weld pool. Due to the small size of the paper and the movement of the seam away from the melt, the melt hardens rapidly as it exits the melt. As a result, asymmetrical melt may be present at the weld site due to variations in the power density in the laser beam, resulting in an asymmetric welding bead. Formation and nonuniform stress characteristics can occur. In addition, this often leads to cracks during the test-cycling of the finished product, which results in the product becoming unusable.

One way to overcome this problem is to use a laser with a continuous low order profile. That is, the use of a laser capable of maintaining a well-controlled output distribution in the cross section of the laser beam over the entire range of the laser output output.

However, it is difficult, but not impossible, to make a constant output distribution in the cross section of the laser beam, and it is more difficult to keep it constant.

As described above, deviations in the weld seam can occur due to machining tolerances or the like. Many studies have been done on how to accurately maintain alignment between the focused laser beam and the weld seam, and some of these methods include magnified vision systems, tactile sensors, magnetism and capacitance. Magnetic and capacitive proximity sensors and digital signal processing (DSP) techniques have been introduced. The method is described in US Pat. 6,040,550, which was used to find the center of the weld seam using a magnification system and a computer. The position of the laser beam was controlled using a mirror, and along the path of the weld seam using the mirror. However, the system is vulnerable to vibration, lacks accuracy in alignment, and in particular lacks compensation for thermal effects such as system alignment can change in response to temperature changes.

Therefore, while the conventional welding method is expensive, there are many disadvantages such as being extremely vulnerable to vibration, temperature and electromagnetic interference from the laser system.

SUMMARY OF THE INVENTION The present invention has been made to improve the above-mentioned conventional problems, and an object thereof is to produce a welded metal bellows, and to increase the throughput of a product, and to consume weld shielding gas during the welding process. To reduce weld volume, reduce contamination by automating the parts that operate the device, and produce welded metal bellows that can produce higher production rates without the need for skilled welders due to lower operating costs. It relates to a welding method and apparatus.

1 shows an embodiment of an outer diameter welding system according to the present invention.

Figure 2 shows an embodiment of the inner diameter welding system according to the present invention.

Figure 3 illustrates the principle of operation of a laser beam delivery mechanism according to the present invention.

Figure 4 illustrates a top and bottom weld clamp ring that can be used in one embodiment of an inner diameter welding system according to the present invention.

Figure 5 shows how the laser beam is guided to the weld seam in one embodiment of an outer diameter welding system according to the present invention.

Figure 6 shows how the laser beam is guided to the weld seam in one embodiment of the inner diameter welding system according to the present invention.

7A and 7B show a comparison between the conventional welding method shown in FIG. 7A and the penetration amount in the laser welding of FIG. 7B.

Explanation of symbols on the main parts of the drawings

19 ... laser output supply 20 ... laser beam generator

21 ... upper laser beam 22 ... lower laser beam

23 ... beam splitter 24 ... beam refraction prism

25 ... Upper Linear Slide Table

26 ... Lower Linear Slide Table

31 ... stepper motor 33 ... vacuum cup

34 ... DC motor 38 ... scanner mirror

39.Welding gas nozzle 40 ... Focus lens

41 ... water diaphragm 42 ... cancer diaphragm

43 ... top clamp ring 44 ... bottom clamp ring

46 ... focusing lens 49 ... CCTV monitor

56 DC motors for lathes 58 solenoid valves

As a technical means for achieving the above object, the present invention comprises: a laser beam generator for generating a laser beam through a laser output supply portion that is addressed to the host computer;

A beam splitter installed in front of the laser beam generator such that the laser beam is spectrally bisected by an appropriate wavelength so that the path can be changed by a scanning mirror which vibrates through a focal lens and a prism and a semicircle over a welding core;

A focus lens installed on the upper and lower linear slider tables so that the reflected laser beam from the scanning mirror is directed to the upper and lower edges of the weld seam; And

The female diaphragm is installed in a clamping fixture that rotates through a DC motor controller and the spoked generator and is supported by an inner diameter clamping surface fixed to the lower side on the inner edge, and the diaphragm is positioned upside down above the female diaphragm. And a cylinder installed to firmly fix the female and female diaphragms by a vacuum cup provided at one end of the arm with the motor.

In this case, the beam reflected from the mirror is guided vertically, characterized in that the nozzle assembly is installed to reach the focus of the weld seam through the focus lens.

In addition, the scanning mirror is installed in the CCTV camera for checking the welding state through the focus lens on the welding core is characterized in that the speech to the monitor.

In addition, the present invention comprises the steps of generating a laser beam through the laser beam generator spoken with the laser output supply by a signal from the host computer;

Irradiating the laser beam onto the welding seam so that the laser beam is spectroscopically divided by the appropriate wavelength of the beam splitter so that the path can be diverted by a scanning mirror which vibrates in a semicircle with the prism through the focus lens over the welding seam;

The female diaphragm welded by the laser beam is installed and supported in a clamping fixture that rotates through a generator, and the upper and lower female diaphragms are positioned upside down to fix the female and female diaphragms by a vacuum cup at one end of the arm. Becoming steps:

The reflected laser beam from the scanning mirror is directed through the focus lens to the upper and lower edges of the weld seam, wherein the oscillating laser beam creates an efficient laser spot larger than the laser spot size, and the oscillating laser beam And welded when the female diaphragm and the water diaphragm are welded when the vibrating laser beam moves along the seam.

As the scanning mirror vibrates in a semicircle, the mirror refraction exiting through angle q ₁ deflects the reflected laser beam through angle q ₂ , where the angle q ₂ = 2q ₁ of the reflected laser beam becomes. It features.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention makes it possible to produce edge welded metal bellows even faster and more reliably using oscillating beam techniques. The present invention can be used to form a convolution pair and bellows capsule by welding a metal bellows diaphragm in one embodiment. The invention also relates to an outer diameter (OD) welding system for the outer seam welding of two diaphragms and an inner diameter (ID) welding system for the inner seam welding.

In welding, it is preferable to weld the inner core first, which is a typical welding method conventionally welded using other welding methods such as manual TIG welding. 2 shows a system for performing the above process. The female diaphragm 42 may be installed in a rotating clamping fixture, which may be supported by an inner diameter clamping surface which is fixed to the bottom above the inner edge. Then, when the male diaphragm 41 is placed upside down on the female diaphragm, the upper movable clamp is lowered by a predetermined air pressure, and the air pressure is firmly fixed to the female and the diaphragm. Apply enough pressure to make it work.

The clamp can be made to rotate at a constant speed through the DC generator 34 by computer control. In this case, the laser beam may be divided into two at an appropriate wavelength by a 50:50 beamsplitter 23. The spectroscopic laser beam can then be redirected by the prism 24 and the scanning mirrors 38, 39 over the focal lens 40, 46 over the weld seam.

The two mirrors 38 and 39 can be fixed frequency scanners, also called resonant scanners, and can be used to position the beam at the weld seam.

As shown in Fig. 6, in the static mode, ie with the scanner output off, the focused laser beam is directed to the upper and lower edges of the weld seam. During the welding process, the scanning mirrors 38 and 39 can vibrate at high speed to move the focused laser spot across the weld seam.

In one embodiment, the focused laser spot may move across the weld seam in the focal plane, and in one embodiment the focused laser spot may move back and forth perpendicular to the weld seam.

3 shows how the laser beam can scan back and forth, the position of the static beam striking the front reflective surface of the scanning mirror 38 as indicated by the thick line 21. The reflected beam exits through the focus lens 40, preferably near normal incidence, and focuses on the focal plane 72.

As the mirror 38 vibrates in a semicircle, the laser beam, which exits through the angle q ₁ , reflects the reflected laser beam through the angle q ₂ , where q ₂ = 2q ₁ . The angle path through the lens repositions the focus of the beam 71a.

In the opposite semicircle, the beam travels almost equidistant from the opposite of the static point 71. The amount of beam refracted by the mirror may be small and may be doubled by the laser beam angular refraction using optical leverage. Therefore, depending on the number of vibrations, the laser spot may appear as a heat source of a constant line rather than as a point heat source.

Thus, the heating position can be adjusted without a non-shifting low-order spatial mode that does not move in the laser beam. In addition, the use of the scanning laser beam of the present invention can reduce the dependence on the use of an expensive seam tracking system.

The laser beam optical delivery system of ID welders and OD welders can be operated on the same principle. As shown in FIG. 5, in the case of an external machine, the laser beam may be preferably guided in a direction perpendicular to the weld seam, and as shown in FIG. 6, the laser beam is guided in the 45 inch angle direction to the weld seam. Can be. In the above embodiment, the inner diameter welding and the outer diameter welding may be performed using one welding machine.

1 shows an embodiment of an outer diameter (OD) welder. The laser beam 21 first strikes the resonant scanner mirror 38 at an angle. In this embodiment, the laser beam is installed in a static mode which does not vibrate, and the beam coming out hits the center of the 45 inch mirror 43. The beam reflected from the mirror 43 is then guided vertically, passing through the center of the focus lens 40 and passing through the hole in the nozzle assembly 44 to reach the focus of the weld seam.

FIG. 9 shows that the diaphragm 54 is held between reusable clamp half rings during the welding process. When the scanner mirror is activated, the focused laser beam traverses up and down the weld joint, and in particular the scanner mirror allows the beam to scan back and forth across the weld joint.

2 illustrates one embodiment of an inner diameter. The laser beam from the laser 20 is distributed into two beams by a 50:50 beam splitter 23. The two distributed beams 21 and 22 follow a similar path towards the weld seam. The laser beam 21 is 90 inch refracted by a beam refracting prism 24 that completely reflects it, and follows a path parallel to the upper beam 21. Resonance scanner mirrors 38 and 39 are installed in static mode so that the reflected beam is guided perpendicular to the center of the focus lens 40, 46. The beam is then positioned close to the upper and lower edges of the weld joint. Therefore, the combined output of the two beams is the sum of the respective outputs.

In this case, the diaphragm may fix the diaphragms 41 and 42 during the welding process by using a clamping method (not shown) of a compressed air driving method. The laser beam can then scan while welding the edges of the shim together.

Figure 3 illustrates the principle of operation of the scanning method of the present invention. The laser beam 21 strikes the reflective surface of the scanner mirror 38 at a predetermined angle so as to strike at a certain angle in a static mode, ie in a non-moving mode. The angle of the mirror may be adjusted such that the outgoing beam is guided perpendicular to the center of the focus lens 40 to move the point 71 in the target plane 72.

The path of the static laser beam is shown in bold in FIG. 3. When the scanner mirror 38 is actuated, the refraction on the semicircle 38a causes the mirror to move through angle q ₁ , which causes the reflected laser beam 21a to pass through the focus lens at angle q ₂ and fall off from the center. . The resulting beam moves away from center and focuses on a point away from vertex 71. Similarly, when the scanner is refracted in the opposite semicircle, the laser beam is refracted at the same distance on the opposite side of the vertex 71. The laser beam thus transmits energy on a thinner line than at one point near the vertex 71. The thickness of the thin line is the diameter of the focused laser beam, and the length of the line is varied depending on the scanning angles of the resonant scanner mirrors 38, 39.

Figure 4 illustrates the basic form of the top and bottom of the weld clamp ring that can be used in the ID welding system of the present invention. The embodiment of Figure 4 shows a cross section of clamp rings suitable for each bellows diaphragm being welded. As described above, manufacturing a clamp ring for each diaphragm is time-consuming and expensive to manufacture, but there is an advantage that the bellows diaphragm can be automatically positioned at the center of the welding fixture.

This greatly reduces the probability that the diaphragm is out of center, which can lower the level of precision required in the pick and place mechanism. Current alignment techniques require a tolerance within +/- 0.0005 inch, but the clamp of the present invention can be increased to a factor of ten (0.1) which is very practical.

5 shows how the laser beam appears at the weld seam in one embodiment of an OD welding system. The difference in angle of incidence in the focus lens can cause the focused laser spot to draw a line across the weld seam, perpendicular to the weld seam, or the like. Preferably the laser is scanned back and forth at a sufficiently high speed that it can be seen as a continuous laser beam that is much wider than the actual laser beam. The width of the laser scan can be adjusted by adjusting the maximum angle of the scanner mirror and the distance from the scanner mirror to the weld seam.

The width of the beam that can be identified in this embodiment can be up to 2-3 times the weld seam thickness, which means that most deviations from the straight seam can be successfully welded without the use of expensive, sophisticated seam tracking systems. To be possible. In one embodiment, the focused laser beam can traverse the welding seam about 5,000 times per second, and overlapping scans in the welded portion are in close contact with each other.

FIG. 6 shows an embodiment showing how the laser beam appears at the weld seam during ID welding. The position of the beam can be adjusted so that the focused beam is directed to the corner of each diaphragm section while the inner diameter welding system is in static mode, ie not scanned. Thus, the scanning mirror is operated to move the position of the laser beam so that the focused beam overlaps the interface of the weld seam, thereby allowing the two diaphragms to melt completely.

7A and 7B illustrate TIG welding and laser welding of a typical welded metal bellows diaphragm pair. Microscopic analysis shows that laser welding is deeper and therefore harder than TIG welding. In the case of laser welding, deeper penetrations are formed for deposition beads of the same size. Most causes of welding failure have been found to occur in heat affected zones (HAZ). The area heated by laser welding (HAZ) may be much smaller than the area heated by TIG welding, which means that the total heat input (time x temperature) during total laser welding is much less than TIG. Because. Therefore, the final stress analysis shows that the welded parts show higher reliability.

The inner diameter ID of the diaphragm may be welded using the inner diameter welding system of the present invention. In one embodiment of the internal race, a hermetic enclosure including any type of CW laser, laser beam steering and delivery optics device having a sufficient output to melt bellows material. Container and compressed air driven clamping system, Stepper motor driven platform driven by air driven vacuum pick and place, How to move male and female diaphragm with pick and place mechanism, Welded conball operated in vacuum A removal mechanism may be used. Lasers and other components can also be installed on the table. A CCTV system can be installed to align the laser with the diaphragm during the welding process, or a desktop computer can be used to control the system. Outer diameter in one embodiment of the system may be used by a larger diaphragm, and for up to ^6-1 / _{2, and} simply changing the welding clamp.

In one embodiment of the invention as described above, the laser system is a solid state continuous wave (CW) Nd: YAG system. The maximum output power of the laser is about 200 watts. In addition, the laser includes a built-in feature, which can be preferably used in the present invention. For example, it can be easily connected to a computer for laser output output control, shutter control, and safety interlocks. For initial installation the laser system can be used in manual operating mode. Other lasers can also be used that produce sufficient power to melt the material to be welded. The lasers that can be used include Nd: YAG, Nd: Glass, Nd: YVO, carbon monoxide, carbon dioxide, chromium, ruby, diode lasers, diode pumped lasers, and derivative lasers for the lasers. to be. All types of continuous wave (CW) lasers and pulsed lasers are also included in the category of lasers that can be used.

As described above, the system of the present invention may use a sealed container, which completely covers the welded portion and the laser optics to prevent dust from accumulating on the laser beam steering mirror to protect it from damage. have. A gas purge prior to the operation of the machine lowers the oxygen content in the sealed device, and preferably eliminates the oxygen in the device. Positive pressure during operation can remove dust and oxygen. Therefore, the welded part can be made cleaner and the content of oxygen can be lowered. The closure device prevents accidental movement or unauthorized adjustment of the laser optical component, thereby increasing reliability. The closed container also allows proper observation of the manufacturing process, while preventing the laser beam from being exposed to unnecessary elements. Argon gas can be recycled to reduce the amount of gas needed for the manufacturing process. The volume of gas consumed when using the method is about 5% to 10% when using the existing method.

In addition, the hermetically sealed container allows the welder to be less exposed to argon gas and prevents the diaphragm from being contaminated before the welding process. The diaphragms are cleaned before welding begins and placed in sealed containers to keep the welder out of fingerprints and skin tissue, water, oil and other contaminants that can degrade the weld.

In one embodiment, the laser beam steering and delivery optics comprises a plurality of flat mirrors, flat convex focus lenses, a single 50:50 beam splitter, a 90 inch prism and beam entry into a container. A beam entrance window can be used. Among such components, in the case of beam entry windows, preferably only one side of the beam entry window is exposed to the atmosphere. And all other elements can be completely enclosed in the welding container. In this way, the laser optics can be kept very clean and can be prevented from being contaminated. Preferably, the access window is not able to greatly modify the laser beam or the path of the laser, but can be easily kept clean.

In the air driven clamp, it can be used to apply pressure between the female and the diaphragm during the ID welding process. The air driven clamp provides several desirable functions. 2 inch stroke air cylinders installed at each end of the upper clamp platform apply downward pressure to fix the male and female diaphragms during the welding process. By controlling the flow and pressure of air, the system can be flexibly applied to bellows of various sizes that can be produced using the present invention.

In a stepper motor driven rotating stage, another air cylinder can be fixed so that it can be used to pick up the non-welded diaphragms under the computer control and into the lower weld clamp. One three position arm can be used to move a vacuum cup specifically designed for diaphragm welding. The cups can in turn be computer controlled via a vacuum solenoid valve. The diaphragm can be picked up and released by opening and closing the solenoid valves connected to a vacuum reservoir. The welded diaphragms (convolutions) are sorted out of the weld clamp area by a third vacuum cup and placed in a carrier for the next step operation.

The purged, non-welded diaphragms are loaded into removable cans for refill and placed in a pick and place mechanism port. The can may include a built in delivery mechanism for conveying the diaphragm, and adjusts the height at which the diaphragm is loaded to maintain a constant height of the vacuum pick and place mechanism cup.

You can observe the septum inside the clamp while adjusting the laser optics using a CCTV system. The viewing optics are from about 40x to 100x magnification, which allows the laser beam to be correctly positioned in relation to the diaphragm edge, and also allows the welding site to be observed during the welding process and to be installed from above or below the work bench. Can be. The optical system may be used for installation purposes and may continue to be used to monitor the welding process as needed.

In one embodiment the optical system is designed such that the CCTV system can be seen through the last focus lens on the weld seam. Thus, an enlarged image of the weld is shown on the TV monitor, making it easy to adjust and install the laser focus and weld seam position accordingly.

In one embodiment, the computer system for controlling the operation of the ID welding system is a desktop type PC with a special connection board. The digital to-analog board controls the laser output and the DC motor speed, and the digital I / O board controls all of the computer's input and output switching functions. The laser interlock can be monitored through the digital I / O port. The data table may store information according to the order of part numbers according to the type and size of each bellows to be manufactured. That is, welding speed, type of material, laser output, laser output ramp, welding overlap, material thickness, convolution diameter and welding clamp information can be stored under part numbers representing the bellows being manufactured. have.

When welding, it is desirable for the computer to control the entire welding process, unless the machine is in setup or in manual mode. While placing the diaphragm in the welding clamp fixture, the upper clamp is lowered in place to ensure that the diaphragms are secured. The computer then instructs the DC monitor to rotate at a constant speed. This rate depends on the size of the diaphragm, the material, and the thickness of the material. A short gas purge can be used to clean the welded area where oxygen is floating.

The laser shutter can then be opened to raise the laser output as needed for welding and maintain the output level until a complete diaphragm convolution is made. A short overlap of the weld ends can confirm that the seam is fully attached. The laser output is then lowered to the standby state, then the laser shutter is closed and the welding gas is turned off. The DC motor stops rotating, retracts the upper clamp and uses a pick and place mechanism to recover the convolution from the weld and replace it with a new diaphragm. The entire process can take from a few seconds (for small convolution) to 30 seconds (for large convolution). Also, the welding speed is generally 40 to 120 inches per minute, which depends on the type and thickness of the material. This speed is a significant improvement over manual TIG welding, with TIG welding taking about 12 inches per minute (for experienced welders).

The outer diameter OD of the convolution may be welded in the outer diameter welding system. In one embodiment of the outer diameter welding system an optical rail, laser beam deflection optics, multiple conveying nozzles and shield plates, CCTV with 200 Watt (max power) CW Nd: YAG laser and resonance scanner The system is available. The laser and other components can be installed on a table. A linearly moving table can be installed on the tabletop to carry shelves with arbors. The arbor carries the convolutions and a copper half ring (not shown) in the order of welding. There is no limit to the maximum outer diameter convolution that can be welded using the system.

In one such embodiment, it is possible to use a solid state continuous wave (CW) laser system comprising a Nd: YAG crystal with a high current Krypton arclamp used as a pump source. The maximum output from the laser is about 200 Watts. It may be used if necessary in the present invention by introducing a built in device. The laser system can be easily connected to a computer for laser output control, shutter control and safety lock. At initial installation, the laser system can be used in manual operating mode.

In one embodiment, the OD welded laser beam is deflected at the distal end of the optical rail by a mirror mounted on the resonance scanner 38. The deflected beam then hits the mirror 43 coated with an insulator and is 90 inch vertically reflected into the center of the focus lens 40. The optical system of this embodiment is designed such that the CCTV system can also be seen through the mirror and the focusing lens on the weld seam coated with an insulator. Thus, an enlarged image of the welded area can be viewed on a TV monitor, which can facilitate installation, laser focusing and welding seam positioning.

Shield gas nozzles may be used in the system. The shielding gas nozzle may contain an argon shielding gas layer between the gas exit port and the welded portion until the weld seam is cooled below the oxidation temperature. In one embodiment, the nozzle design allows only 5% to 10% of the gas flow rates typically used in TIG systems. The focus lens and nozzle are integrated into a package that can be easily adjusted to ensure that the gas nozzle is correctly positioned from the weld when the correct focus position is found through a CCTV monitor.

The linear motion table can support a shelf that can accommodate a bellows capsule assembly of maximum diameter and maximum length that can be welded in the system. In one embodiment, the linear motion table can move approximately 16 inches, and can load more than 20 lbs. The table can be controlled using an indexing drive and a computer program, thus moving the table forward by one convolution pitch for each welding sequence. Using the program used to control the motion of the table, information about the welding and motion parameters can be obtained from input information such as part numbers for the particular bellows type produced.

In one embodiment, the computer system for controlling the operation of the ID system is a desktop PC with a specific interface board and software packages associated with the operation. The connection board controls the laser output and the DC motor speed, and another connection board controls all the switching functions inside and outside the computer. The laser lock can be monitored via the digital I / O port. The data table may contain information about each type and size of bellows to be manufactured, sorted according to part number order or the like. Parts representing the bellows type in which information on welding speed, material type, laser output, laser output ramp, welding overlap, material thickness, convolution diameter and weld clamp, and half ring will be manufactured Can be stored below the number.

The half ring, for example, may be specially made for the bellows type to be welded to the copper half ring. The rings can be fabricated to assist in removing heat from the weld edge and to support against buckling applied to the edge during the welding process. The rings used in the prior art have been disposed of after use, and in contrast, in the present invention, recyclable rings can be used, which can be easily removed from the welded bellows.

While working in the ID welding apparatus of the present invention, the bellows diaphragms are provided with a pick-and-place arm, a stepper motor, an air cylinder and a vacuum cup to the welding clamp. Can be placed using. This method of movement can maintain a constant feed rate without obstacles, and by reducing or eliminating the manual work of the welder, it is possible to prevent contamination due to skin scratches and sebum. It also prevents contamination due to particles that may fall from the protective gloves worn by the welder. The method can eliminate errors occurring in diaphragm placement and lower the required level of proficiency of the welder. Automatic movement of the diaphragm allows a welder to operate multiple machines without having to watch throughout the welding process. This eliminates the need for a large number of skilled welders in welding, thus reducing manufacturing costs.

In one embodiment, the bellows diaphragms are filled and then filled in a closed container (described below) and filled with a shielding gas. The top closure cover can be removed and containers can be installed under the pick-and-place arm before welding. This packaging method provides one or more of the advantages described below. If bellows diaphragms are not needed immediately, they can be stored in the container until used. Filling the shielding gas prevents the surface from oxidizing, making the weld cleaner and stronger. Since the diaphragm is not damaged or missing, product throughput can be increased. A common method of handling the diaphragm before welding is to pair the diaphragms two on a stainless steel wire. Often during this process, the diaphragms are dropped on the floor, damaging the edges and contaminated by dust and the like.

In one embodiment, the laser beam is split into two beams, for example having approximately the same output, before being moved to the weld seam. Or two separate beams may be used.

The present invention overcomes the drawbacks of splitting the beam into two beams, preferably of equal power, leading the beam at an opposite side of the weld seam and leading it at an acute angle. By inducing in the above manner, the heat field can be uniformly distributed, which makes the welding symmetrical. (See FIG. 6) The system of the present invention also allows for welding without the elliptical laser spot by vibrating the beam, as shown in FIGS. 3 and 5. This beam guidance method can also provide other advantages. The final focus lens 40 is located far from the weld so that the weld spatter is less in contact with the lens. It also allows welders to maintain and maintain a cleaner area around the weld clamps and optical system. Because the distance from the lens to the welding zone is far enough, when using bellows of different sizes, there is sufficient distance to change the welding half-type clamps 43 and 44 without removing or obstructing the beam guidance mechanism. can do.

The dimension and symmetry of the weld beads can be adjusted through the independent positions of the two laser beam spots. When the beam is separated and 45 inch rejoined from the weld seam, some but not all of the laser energy irradiated to the edge of the weld seam can be reflected back by the weld clamp wall that is polished in the face of the weld seam. Thus, more laser energy is used to melt the diaphragm material, allowing welding at lower power, or making welding faster or at higher power.

The apparatus of the present invention is heated during use, causing the laser beam to float less from the weld seam. Preferably, there is no optical component so close to the weld that it is affected by the welding process to move or damage. Because of the openness, nothing can affect the weld gas coverage around the weld to make the weld more consistent and clean. The vapor pressure over the weld pool applies a slight pressure to the surface of the melt pool. By vibrating the beam in the manner described above, there is an effect of equalizing the variation in the melt volume caused by the burrs at the edge of the rolled diaphragm. By using split beams the limit on inner diameter welding is reduced. With the system of the present invention it is possible to weld the inner diameter of less than 1/8 inch diameter, there is no limit to welding larger diameter than this.

By installing a CCTV camera 50 can be focused on the laser beam exactly on the weld seam. This can usually be used not only to install the system, but also to monitor the welding process. The camera looks through laser optics and allows you to see the welding process in real time. Weld gas induction nozzles can independently adjust the XYZ position through a 3-axis translation stage, and thus precisely adjust the gas distribution above the weld point, thus ensuring accurate positioning for a robust and clean weld. This is necessary.

In order to fully cover the weld seam in case of drift or run-out due to machining tolerances, the laser beam may be oscillated in the vertical plane rather than guided in a static manner. The required oscillation angle is small and can be adjusted to cover at least three to four times the weld seam width. With this vibration, the beam guidance method offers several advantages. Because the beam vibrates rapidly over the weld joint, it appears to be a continuous beam that looks much wider than it actually is. Therefore, even if the welding seam shows a deviation vertically or horizontally from the intermediate position, the laser beam can cover the welding seam, thereby enabling continuous welding.

5, 5a, 6 and 6a, the related principle is shown applied to the inner diameter welding system and the outer diameter welding system. If the bellows diaphragm is not correctly positioned and shows a slight radial runout, if the static beam is guided, the weld will be poor as a result of total weld failure. The constant heat field provided by the vibrating laser beam of the present invention effectively eliminates the asymmetric welding phenomenon commonly seen (see FIG. 10) and allows all metals to be uniformly melted. In the case of high power laser beams, the power density across the cross section of the beam tends to be inconsistent. The degree of inconsistency depends on the change of the output level according to the welding process. It also depends on the spot of focus. The spot size of the beam focus during the welding process is related to the size of the welding material. At typical constant focal spots, weld seam variations or power variations will melt faster at the highest power density (on one side of the seam).

Accordingly, rugged, irregular, asymmetrical, and even some parts will appear as welds that are not welded. The beam vibration described in the method of the present invention has the effect of mixing the beam well, thereby providing a constant power density at the beam cross section during power ramping (laser output rises and falls at the start and end of welding). To indicate.

As described in the above method, the wider beam coverage afforded by the beam vibration provided by the present invention has a wider machining tolerance in the inner diameter clamp, which makes the clamp easier and faster to produce. The degree of welder skill becomes less important and product throughput increases because fewer rejected parts.

Initial setup for new bellows sizes and clamps is easy. Beam vibration mirrors and laser beam guidance optics are installed in a common translation stage 25, 26 to allow the associated optical components to be fixed in their respective relationships. By converting these stages internally and externally, larger or smaller diameters can be welded with minimal effort. A red light sighting laser can be used to position the beam at the weld joint. The tolerance for laser beam positioning is on the order of +/- 0.01 inch from the ideal position. In some prior systems, the beam had to be positioned exactly within +/- 0.001 inch above the weld seam to produce a consistent weld bead. This shows the difference in accuracy required for successful welding. When the new setting is implemented, the requirement to continuously monitor by beam vibration and 45 inch beam alignment for weld seam / laser beam alignment can be reduced, as shown in FIG.

As the coverage is increased by the beam vibration, more laser output can be reflected from the face of the welding clamp and transmitted to the weld. This allows larger penetration (see FIG. 7B) than when welding using the conventional welding method (see FIG. 7A).

By using the inner diameter clamp design provided by the present invention, it is easy to convert from one bellows size to another without going through complicated set up or alignment procedures. In one embodiment there are two parts to change: the upper and lower half clamps, which are manually compressed in the rotary bearing. These bearings are used as reference surfaces for laser and clamp alignment and can also be used repeatedly between various clamp sizes. The time taken to replace the clamp is about 10-15 minutes and the clamp design of the present invention is quite unique and has some additional advantages. The clamp inserts (43-44 in FIG. 4) can be rolled into the round steel plate before final work. This allows you to check whether the half clamps are working properly and whether they are parallel to the reference plane, and whether the clamps are working as designed and working to a certain reference level. The insert allows the clamp face to be reworked and replaced as needed without any cost. Replacing the inserts is much cheaper and faster than replacing the entire clamp.

In one embodiment, the worked profile (Figs. 4, 43-44) over the insert may fit exactly with the profile of the bellows septum. This allows the clamp to remain loose (+/- 0.002 inch) without having to be made to meet extreme tolerances. In this way, the slight profile of the diaphragm in the clamp with the profile shown on the clamp surface is effective in aligning itself, thus reducing the tolerance of the pick-and-place mechanism and lowering the manufacturing cost. . In addition, there are no steps that would result in damage from providing or contaminating the source. In addition, the clamp of the present invention can keep the gloss much easier and cleaner.

The clamp design of the present invention enables effective heat-sinking, improves the safety of the clamping mechanism and extends its life. This improves the quality of the weld by removing the approaching heat more effectively and reducing the likelihood of the steel diaphragm burning.

As briefly discussed at the top, the bellows diaphragm of the present invention may be stored in a closed container before being loaded into an inner diameter welding machine. These containers provide many functions that affect the productivity and quality of the final product. The containers 93, in one embodiment, may be made using transparent Plexiglas or other transparent material. Other materials may be used, but this material allows the welder to see the interior of the bellows diaphragm, count the number of parts remaining, and identify the contents. A water diaphragm may be loaded in one container and a dark diaphragm in another container, and may be fixed to the bottom of the inner diameter welding station through a spring clip 102. The clips can securely hold containers against an airtight seal beneath the workbench to keep them clean. The third container can be secured to the bottom of the workbench and hold the welded convolutions retrieved by the pick-and-place mechanism. Immediately connected to the system, an internal motor drive screw 94 can be raised after rotating the platform 95, on which the diaphragms 91 are loaded. This allows the diaphragm on the top floor to be retrieved and placed in place using a pick-and-place mechanism through a vibrating cup. As the diaphragms are removed, the sensors in the container sense a change in the level of the diaphragm at the top and allow the motor-driven screw to rotate to maintain the correct height for the pick-and-place suction cup. Do it. This process can continue until the final diaphragm is lifted from the container, where another sensor sends a signal to the computer indicating that the container is empty, allowing the welder to replace the empty container with a new container unit. At this point, the welder can stop the work by pressing the resume button on the computer keyboard. One container can hold enough bellows diaphragm (1200-1500 convolution) to work for about four hours in a row. As soon as the welded convolution is withdrawn from the weld, the pick-and-place arm can place the newly welded convolutions into a third empty container. This container can only accept welded convolutions. When the computer detects a certain value entered, the system tells the welder to replace the container. The container is then removed and sealed before being transferred to the outer diameter welding system. In this way, an accurate measurement of the inventory (the computer tracks all welded convolutions) and all production can be kept absolutely clean. Throughout the inner diameter welding process, the welder does not have to touch any diaphragm directly and can only handle it through a closed container.

The outer diameter welder of the present invention can use laser beam vibration, as described above in one embodiment of the inner diameter welding apparatus. This vibration yields the same advantages discussed in internal diameter welding systems. With regard to weld seam coverage of the above methods, the use of expensive and sophisticated optical, mechanical or seam tracking mechanisms may or may not be used.

In the design of the present invention, the laser beam can be directed to a weld seam that is perpendicular to the center line of the bellows. This allows the welder to ensure maximum safety from being exposed to the laser beam, such as when changing the bellows size and when maintaining the bellows. In one embodiment, the laser beam is safely absorbed by the aluminum plate if the welder starts the welding process without the part to be welded accidentally.

The outer diameter welding device of the present invention may introduce a CCTV camera 50 used to monitor the weld seam using the same components as the laser optical components. Therefore, the laser can be easily focused on the weld seam, which can be easily done by simply lowering the welding nozzle until the image on the CCTV monitor is clearly captured. The target shown on the monitor indicates the position of the laser beam with respect to the seam, making positioning easy. In order to make laser beam positioning easier, a red sighting laser can be used.

The apparatus of the present invention can use standard, commercially available products to vibrate the laser beam in the manner described above. Such devices could be small mirrors attached to the unfixed end of a fixed shaft made to twist at a constant frequency. The amplitude of the torsion can be adjusted according to a large or small path. In one embodiment of the invention, two of these devices may be in the inner diameter welding system 38, 38 inch, and one device may be used in the outer diameter welding system 38.

The welding shielding gas may be coaxially guided through a laser beam guide nozzle 39 located proximate to the welding point on the weld seam. Therefore, the shielding gas may be emitted in the same direction as the laser beam in a thin layer in proximity to the welding core. At the welding site, the shielding gas can be applied to both sides, thereby covering the welding site with the shielding gas. This can greatly reduce the amount of shielding gas flowing while maintaining good welding operation. It also reduces production costs and prevents welders from creating oxygen deficiencies due to the dense concentration of shielding gas. The system of the present invention may use an air driven, low-flow vacuum system installed to remove the shielding gas used and to discharge the shielding gas out of the building.

The welding parameter storage and control method of the present invention allows easy access to many operating features associated with bellows welding. Welding parameters can be entered from information recorded in a logbook. When setting up the machine of the present invention with as many parameters as possible, it will be difficult to exactly repeat the welding process that was at some point in the past. This is due to possible adjustments to the clamp, clamp pressure, laser, and optical components. In addition, the diaphragms may be from different heat batches, and there may be other subtle differences that affect the welding. By using the above logbook, an accurate operating parameter can be obtained. In order to obtain good repeatable results, it is only necessary to arrange the welding parameters for a while.

The welding ring design used in the conventional welding method has its limitations. When this style of welding ring is used, the diaphragm material cannot be melted sufficiently, resulting in a shallow penetration and consequently weak welding. The design of the present invention makes it possible to weld with repeatability much more successfully and reliably.

In the design of this embodiment, the ring is not using steps or notches on the outer edge of the ring. Instead, it has 45-inch slope edges that offer some advantages over staircase or notch designs. The sloped edge on the ring of the present invention can be very shiny with the machine. The slope can be used to make the ring easier and faster at a lower price. The slopes are easier to keep clean than stairs or notches and hold less contaminants. The slope reflects the laser light back from the side to the weld seam, thereby increasing the amount of available laser energy available for welding. In addition, because of the less absorption due to the polished surface of the design of the present invention, the ring can be kept clean for a longer period of time, allowing less impurities to be contained in the weld root than in a stepped design. In one embodiment of the present invention, the ring can be divided into two equally sized parts, designed to be recyclable, easy to remove, and reused up to at least 30 times prior to disposal, thereby reducing manufacturing costs. do. Sloped edges provide better control of deposit bead thickness. This is important for bellows cycle life (expansion / detraction cycle before failure). The rings may be inserted after the end of the inner diameter welding. In this way, a pile of welded convolutions are stored in an inventory that can be used to make bellows when needed. The rings are recyclable and require fewer rings than before.

The bellows diaphragm is loaded in a sealed container and attached to the underside of the welding table (inner diameter system). These containers are sealed prior to installation and can be unsealed when the containers are connected to the operating system via short control cables. By using this method, it is possible to reduce the propagation of the gas in the welding chamber. The gas pressure in the chamber can be monitored by computer adjustment and, if necessary (in the case of internal-diameter systems), a fresh shield gas can be introduced through the control port. This allows the amount of gas to be controlled while minimizing its escape to the atmosphere. The bellows diaphragm is moved by a pick-and-place arm using a vacuum cup (inner diameter system) from the containers to the weld. In this vacuum system, larger diaphragms can be discharged and a very small but naturally drawn shielding gas is drawn from the welding chamber. The vacuum cup may push down the diaphragms before the vacuum is initiated through a computer controlled solenoid valve.

The welding ring design of the present invention may enable recycling (in an outer diameter system). Previous weld rings had one thin sawcut, which had a pick inserted into the sawcut to remove the weld ring from the welded bellows site. Using this method, the ring would have been warped and the once used ring had to be discarded. This also means that one ring is required for every bellows convolution. In the design of the present invention shown in FIG. 9, two sawcuts were inserted and two half rings of the same size were made. This makes it easy to remove the weld ring without using picks or twisting the ring. In this way the rings can be reassembled onto a new convolution and reused to create a new bellows. With the design of the present invention, the ring can be reused at least 30-50 times before discarding. This means that one set of rings can produce 50 sets of (or more) convolutions, which significantly lowers manufacturing costs for machine time, welding ring material, and recycling or disposal of crushed metal. It is.

According to the welding method and apparatus of the present invention as described above, when manufacturing the welded metal bellows, it is possible to increase the throughput of the product, reduce the volume of weld shielding gas consumed during the welding process, and operates the device By automating the parts, the contamination is reduced, and the operating cost of welding is low, and there is an excellent effect of achieving a higher production rate without requiring a skilled welder.

While the invention has been shown and described with respect to specific embodiments thereof, it will be appreciated that various changes and modifications can be made in the art without departing from the spirit or scope of the invention as set forth in the following claims. Those of ordinary skill will want to know easily.

Claims (5)

A laser beam generator 20 through which a laser beam is generated via a laser output supply unit 19 that is communicated with the host computer 66; The laser beam is spectrally bisected by the appropriate wavelength so that the path can be diverted by the scanning mirrors 38 and 39 which oscillate in a semicircle with the prism 24 over the focal lenses 40 and 46 above the weld seam. A beam splitter 23 installed in front of the laser beam generator; A focus lens 40 mounted on the upper and lower linear slider tables 25 and 26 so that the reflected laser beams from the scanning mirrors 38 and 39 are directed to the upper and lower edges of the weld seam; And The arm diaphragm 42 is installed in a clamping fixture that rotates through the generator 34 spoken with the DC motor controller 59 and is supported by an inner diameter clamping surface fixed at the bottom above the inner edge, The cylinder 36 is installed so that the male and female diaphragms are firmly fixed by the vacuum cup 33 provided at one end of the arm 32, which is positioned upside down, above the diaphragm 42. Welding device, characterized in that configured to include. 2. A welding device according to claim 1, wherein the nozzle assembly (44) is installed such that the beam reflected from the scanning mirror is guided vertically to reach the focus of the weld seam through the focus lens (40). The welding device according to claim 1, wherein the scanning mirror is installed with a CCTV camera (50) for checking a welding state through a focus lens on a welding core and is spoken with a monitor (48). Generating a laser beam through a laser beam generator spoken with a laser output supply by a signal from a host computer; Irradiating the laser beam onto the welding seam so that the laser beam is spectroscopically divided by the appropriate wavelength of the beam splitter so that the path can be diverted by a scanning mirror which vibrates in a semicircle with the prism through the focus lens over the welding seam; The female diaphragm welded by the laser beam is installed and supported in a clamping fixture that rotates through a generator, and the upper and lower female diaphragms are positioned upside down to fix the female and female diaphragms by a vacuum cup at one end of the arm. Becoming steps: The reflected laser beam from the scanning mirror is directed through the focus lens to the upper and lower edges of the weld seam, wherein the oscillating laser beam creates an efficient laser spot larger than the laser spot size, and the oscillating laser beam According to the welding method, wherein the female diaphragm and the water diaphragm are welded when the vibrating laser beam moves along the core. The laser beam of claim 4, wherein the scanning mirror vibrates in a semicircle, thereby refracting the reflected laser beam through the angle q ₁ through the angle q ₂ , wherein the angle q ₂ of the reflected laser beam is reflected. = 2q ₁ welding method.