A method of manufacturing edge welded bellows

Abstract

Method of manufacturing edge-welded bellows with precise alignment, by stamping first 100 and second annular diaphragm membranes 200, pairing the two diaphragms, welding around their inner circumferen

Description

Field of the Invention The present invention relates to a method for manufacturing an edge welded bellows, in particular a method for precisely aligning and welding the components of an edge welded bellows. Background Edge welded bellows are flexible, hermetically sealed components that are used as seals, springs or vibration isolators. Edge welded bellows are often used to absorb movements, frequently within ultra-high vacuum systems. Due to the ubiquity of edge welded bellows in these high performance systems, there is a strong demand for their rapid manufacture. Additionally, as secondary components within these systems, there is a significant need for the manufacturing process by which they are made to be flexible to accommodate the many sizes and lengths of edge welded bellows required in practice. Objects and aspects of the present invention seek to address the above. Summary of Invention According to the present invention, there is provided a method of manufacturing edge welded bellows, the method comprising the steps of: manufacturing a plurality of convolutions, each convolution within the plurality of convolutions manufactured by: stamping a sheet to form an annular first half convolution with a first shape; stamping a sheet to form an annular second half convolution with a second shape; pairing the first half convolution with the second half convolution, and welding the first half convolution and the second half convolution together around their inner diameters to create a convolution with a central aperture; fitting a spacer to each convolution, wherein the spacer separates the external diameter of the first half convolution from the external diameter of the second half convolution; sorting the convolutions such that the first half convolution of each convolution is adjacent to a second half convolution of another convolution to form a series of convolutions; mounting the series of convolutions on a mounting tool that extends through the central aperture of each convolution; compressing the series of convolutions along the longitudinal axis of the mounting tool such that each convolution is in contact with its adjacent convolutions within the series of convolutions; using an alignment tool to exert radial pressure around the circumference of each convolution within the series of convolutions to precisely radially align each convolution within the series of convolutions; removing the alignment tool; welding each convolution within the series of convolutions to its adjacent convolutions around their external diameter to form an edge welded bellows. In this way, the convolutions can be aligned to within the required tolerance of 0.004” (100 pm) as required in the manufacturing process. In this way, an advantageous method is provided by which an edge-welded bellows can be manufactured in a rapid and flexible process. As such, customer needs can be accommodated as required, and edge welded bellows of varying lengths can be provided using the same manufacturing process as it is only necessary to vary the number of convolutions used during the manufacturing process. Preferably, the method further comprises removing the edge welded bellows from the mounting tool. Preferably, the method further comprises the step of removing the spacers. Preferably, the method comprises the further step of welding a first flange to a first end of the edge welded bellows. In this way, the edge welded bellows may be connected to a further piece of apparatus using the first flange. More preferably, the method comprises the further step of welding a second flange to a second end of the edge welded bellows. In this way, the edge welded bellows may be connected to other pieces of apparatus, or the same piece of apparatus, by the first and second flanges. In this way, the installation of the edge welded bellows by the user may be eased. Preferably, the step of welding each convolution within the series of convolutions to its adjacent convolutions around their external diameter to form an edge welded bellows comprises rotating the series of convolutions. The rotation of the series of convolutions may allow the accuracy of the welding process to be increased. Preferably, the step of welding each convolution within the series of convolutions to its adjacent convolutions around their external diameter to form an edge welded bellows comprises welding each convolution to its neighbouring convolutions in turn. By conducting each weld in series, the reliability of each weld may be increased and the reliability of the edge welded bellows improved. Preferably, the edge welded bellows is leak tested. Preferably, the alignment tool is a tapered cylinder. The use of a tapered cylinder may be advantageous in increasing the ease with which the series of convolutions may be aligned. Preferably, the step of using an alignment tool to exert radial pressure around the circumference of each convolution within the series of convolutions to precisely radially align each convolution within the series of convolutions comprises further compressing the series of convolutions along the longitudinal axis of the mounting tool. In this way, the series of convolutions can be brought into close proximity and precisely aligned in a convenient process. Preferably, each first half convolution has a thickness below or equal to 250 pm. More preferably, each first half convolution has a thickness below or equal to 150 pm. Still more preferably, each first half convolution has a thickness below or equal to 100 pm. Preferably, each second half convolution has a thickness below or equal to 250 pm. More preferably, each second half convolution has a thickness below or equal to 150 pm. Still more preferably, each second half convolution has a thickness below or equal to 100 pm.Preferably, the first and / or second half convolution is a metal or alloy. More preferably, the first and / or second half convolution is steel, stainless steel, Monel, Hastelloy, Inconel or titanium. Preferably, the method comprises the further steps of manufacturing a second edge welded bellows, and then welding the first edge welded bellows to the second edge welded bellows. In this way, long sections of edge welded bellows may be more conveniently produced. Preferably, the first shape and the second shape are complementary. More preferably, the first shape and the second shape are male and female counterparts. In this way, the edge welded bellows may collapse into a small footprint and / or stack. Alternatively, the first shape and the second shape are identical. Alternatively, the first shape and the second shape are different to one another. Preferably, the process of stamping the first half convolution and / or the second half convolution comprises the use of a rubber insert. In this way, the half convolutions can be shaped and formed in a single action. Preferably, at least one welding step comprises plasma welding. Preferably, the edge welded bellows have an outer diameter less than 200 mm. Detailed Description Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is an image of a first half convolution and a second half convolution; Figure 2 is an image of a convolution; Figure 3 is an image of the convolution of Figure 2, where a half spacer is being inserted between the first half convolution and the second half convolution; Figure 4 is an image of a series of convolutions stacked together; Figure 5 includes an image of a mounting tool and an image of the series of convolutions depicted in Figure 4 mounted on the mounting tool; Figure 6 includes an image of an alignment tool and an image of the alignment tool around the series of convolutions mounted on the mounting tool; Figure 7 is an image of the aligned series of convolutions mounted for welding; and Figure 8 is an image of an edge welded bellows attached to two non-specific flanges. With reference to Figure 1, there is depicted a first half convolution 100 and a second half convolution 200. Here, both the first half convolution 100 and the second half convolution 200 are annular pieces of stainless steel stamped and formed in a stamping process. In the stamping process, the first half convolution 100 and the second half convolution 200 have been shaped using a rubber insert such that they are shaped and formed in a single action. The thickness of the stainless steel in the first half convolution is 100 pm, and the thickness of the stainless steel in the second half convolution is also 100 pm. Embodiments where the thickness of the metal in the first and second half convolutions is different are also envisaged. Both the first 100 and the second 200 half convolutions have a central aperture 110, 210. Both central apertures 110, 210 have an identical diameter and, additionally, both the first 100 and the second 200 half convolutions have an identical outer diameter. However, not all features of the first 100 and second 200 half convolutions are identical. As can be seen in Figure 1, the first half convolution 100 has a first shape, and the second half convolution 200 has a second shape. Here, the first shape and the second shape are complementary to one another. As such, when rested on top of each other, the first 100 and second 200 half convolutions nest neatly. Turning to Figure 2, there is a convolution 300 constructed from the first 100 and the second half convolutions of Figure 1. Here, the convolution 300 has been constructed by aligning the first 100 and second 200 half convolutions with one another such that their central apertures 110, 210 are in complete overlap, and then by welding the first 100 and second 200 half convolutions together around their inner diameters. Here, plasma welding has been used to form the convolution 300, although other kinds of welding may also be suitable. As such, the convolution has a central aperture 310 that has an identical diameter to the central apertures 110, 210 of the first 100 and second 200 half convolutions. Additionally, the outer diameter of the convolution 300 is identical to the outer diameter of the first 100 and second 200 half convolutions. The process illustrated in Figures 1 and 2 may be repeated as many times as desired to form several convolutions 300. Figure 3 depicts a convolution 300 as seen in Figure 2 where a half spacer 400 has been inserted. The half spacer 400 is inserted into the convolution 300 such that it lies between the first 100 and second 200 half convolutions, urging the first half convolution 100 away from the second half convolution 200. Hence, the first 100 and the second 200 half convolutions remain spaced apart from one another. To ensure the first 100 and second 200 half convolutions are evenly spaced from one another around their entire outer diameter, more than one half spacer 400 combine to extend around the outer diameter of the convolution 300. Typically, the half spacer 400 comprises or consists of steel, although other materials (including brass) may be preferred. After the half spacers 400 have been inserted, a plurality of convolutions 300 may be arranged to provide the series of convolutions 500 depicted in Figure 4. Here, the series of convolutions 500 includes several individual convolutions 300 stacked such that the first half convolution 100 of each convolution 300 within the series of convolutions 500 is adjacent to the second half convolution 200 of an adjacent convolution 300 within the series of convolutions 500. As such, the series of convolutions 500 is an alternating stack of half convolutions with the first shape and the second shape. In the series of convolutions 500, the individual convolutions 300 are aligned such that the central aperture 310 of each convolution is aligned. Additionally, the outer circumferences of each convolution 300 within the series of convolutions 500 are generally aligned. Once the series of convolutions 500 has been formed, it can be mounted on a mounting tool 600 as seen in Figure 5. The mounting tool 600 has generally the shape of a dumbbell with a narrow central portion 610, and wider first 620 and second 630 removable ends. Here, the first 620 and second 630 ends are held on to the central portion 610 by screw threads (not shown). As seen in Figure 5, the series of convolutions 500 is mounted on to the mounting tool 600 by first removing the first end 620 from the central portion 610. Subsequently, the central portion 610 of the mounting tool 600 is placed through the central apertures 310 of each convolution 300 within the series of convolutions 500. As such, the series of convolutions 500 extends along substantially the entire length of the central portion 610 of the mounting tool. Subsequently, the first end 620 of the mounting tool 600 is screwed back on to the central portion 610 such that the series of convolutions 500 is compressed slightly in the longitudinal direction. In this way, each convolution 300 within the series of convolutions 500 abuts its neighbours at its outer circumference. Whilst the method so far brings the convolutions 300 within the series of convolutions 500 into general alignment, a greater degree of alignment is required before the final welding stages to create the edge welded bellows. As such, an alignment tool 700 as shown in Figure 6 is used to obtain the greater level of alignment required. Here, the alignment tool 700 is a tapered cylinder, where the cylinder has an internal diameter slightly larger than the outer diameter of the series of convolutions 500. Additionally, the alignment tool 700 has a series of longitudinal slits 710 that extend along the outer surface of the alignment tool 700. As can be seen in Figure 6, this alignment tool 700 includes three longitudinal slits evenly spaced around the outer circumference of the alignment tool 700. In use, these slits allow the alignment tool 700 to be compressed such that its inner diameter is reduced. To align the convolutions 300 within the series of convolutions 500, the alignment tool 700 is placed around the series of convolutions 500 on the mounting tool 600. As such, the series of convolutions 500 abuts the first end 620 of the mounting tool 600 at a first end, the second end 620 of the mounting tool 600 at a second end and the alignment tool 700 around its outer circumference. In the alignment process, the alignment tool 700 is placed under compressive pressure in the radial direction, here by a vice 720, such that due to the longitudinal slits 710 the internal diameter of the alignment tool 700 is reduced. Consequently, the convolutions 300 within the series of convolutions 500 are pushed into radial alignment. To further increase the alignment of the series of convolutions 500, the first end 620 and / or the second end 630 of the mounting tool 600 may be further tightened to reduce the effective length of the central portion 610. This process compresses the series of convolutions 500 in the longitudinal direction and, in combination with the alignment tool 700, increases the alignment of the convolutions 300 within the series of convolutions 500. After the alignment process, the mounting tool 600 containing the now completely aligned series of convolutions 500 is removed from the alignment tool 700. After alignment, the series of convolutions 500 is connected via the mounting tool 600 to a rotatable stage 800 as seen in Figure 7. Here, the aligned outer perimeter of each convolution 300 within the series of convolutions 500 is exposed, such that each convolution 300 may be welded to its neighbours around its outer periphery. In some embodiments of the invention, it may be preferred to weld each convolution 300 to its neighbours simultaneously. In other embodiments, it may be preferred to conduct each weld individually in a stepped process. In either process, the welding of the outer perimeter of the convolutions 300 within the series of convolutions 500 may be eased by rotating the series of convolutions via the rotatable stage 800. Here, the series of convolutions 500 is rotated around its longitudinal axis. Again, plasma welding may be preferred in this stage of the manufacturing process. Once the welding is complete, the series of convolutions 500 has been formed into an edge welded bellows 900. After each convolution 300 has been welded to its neighbours in the series of convolutions 500, the mounting tool 600 is removed from the rotatable stage 800. Subsequently, the edge welded bellows 900 are removed from the mounting tool 600, via removal of the first 620 or second 630 end. Subsequently, the half spacers 400 are removed from the edge welded bellows, facilitated by the flexibility of the edge welded bellows 900 structure. The edge welded bellows 900 may also be leak tested to check the quality of the welds. Additionally, the edge welded bellows 900 may be welded to a second set of edge welded bellows if 5 desired. It may also be that the edge welded bellows is welded to one or two flanges, such that the edge welded bellows 900 can be attached to other equipment by a user. After manufacture, the edge welded bellows 900 appear as shown in Figure 8. Here, the edge welded bellows 900 are attached to a first flange 910 at a first end and a second flange 920 10 at a second end. The flanges 910, 920 may be welded to the edge welded bellows 900 using plasma welding as required.

Claims

1. A method of manufacturing edge welded bellows, the method comprising the steps of:manufacturing a plurality of convolutions, each convolution within the plurality of convolutions manufactured by:stamping a sheet to form an annular first half convolution with a first shape;stamping a sheet to form an annular second half convolution with a second shape;pairing the first half convolution with the second half convolution, and welding the first half convolution and the second half convolution together around their inner diameters to create a convolution with a central aperture;fitting a spacer to each convolution, wherein the spacer separates the external diameter of the first half convolution from the external diameter of the second half convolution;sorting the convolutions such that the first half convolution of each convolution is adjacent to a second half convolution of another convolution to form a series of convolutions;mounting the series of convolutions on a mounting tool that extends through the central aperture of each convolution;compressing the series of convolutions along the longitudinal axis of the mounting tool such that each convolution is in contact with its adjacent convolutions within the series of convolutions;using an alignment tool to exert radial pressure around the circumference of each convolution within the series of convolutions to radially align each convolution within the series of convolutions;removing the alignment tool;welding each convolution within the series of convolutions to its adjacent convolutions around their external diameter to form an edge welded bellows.

2. The method of claim 1, wherein the method further comprises removing the edge welded bellows from the mounting tool.

3. The method of claim 1 or claim 2, wherein the method further comprises the step of removing the spacers.

4. The method of any one preceding claim, wherein the method comprises the further step of welding a first flange to a first end of the edge welded bellows.

5. The method of claim 5, wherein the method comprises the further step of welding a second flange to a second end of the edge welded bellows.

6. The method of any one preceding claim, wherein the step of welding each convolution within the series of convolutions to its adjacent convolutions around their external diameter to form an edge welded bellows comprises rotating the series of convolutions.

7. The method of any one preceding claim, wherein the step of welding each convolution within the series of convolutions to its adjacent convolutions around their external diameter to form an edge welded bellows comprises welding each convolution to its neighbouring convolutions in turn.

8. The method of any one preceding claim, wherein the edge welded bellows is leak tested.

9. The method of any one preceding claim, wherein the alignment tool is a tapered cylinder.

10. The method of claim 9, wherein the step of using an alignment tool to exert radial pressure around the circumference of each convolution within the series of convolutions to radially align each convolution within the series of convolutions comprises further compressing the series of convolutions along the longitudinal axis of the mounting tool.

11. The method of any one preceding claim, wherein each first half convolution has a thickness below or equal to 250 pm.

12. The method of any one preceding claim, wherein each second half convolution has a thickness below or equal to 250 pm.

13. The method of any one preceding claim, wherein the first and / or second half convolution is a metal or alloy.

14. The method of claim 13, wherein the first and / or second half convolution is steel, stainless steel, Monel, Hastelloy, Inconel or titanium.

15. The method of any one preceding claim, where the method comprises the further steps of manufacturing a second edge welded bellows, and then welding the first edge welded bellows to the second edge welded bellows.

16. The method of any one preceding claim, wherein the first shape and the second shape are complementary.

17. The method of any one preceding claim, wherein the first shape and the second shape are identical.

18. The method of any one preceding claim, wherein the process of stamping the first half convolution and / or the second half convolution comprises the use of a rubber insert.

19. The method of any one preceding claim, wherein at least one welding step comprises plasma welding.

20. The method of any one preceding claim, wherein the edge welded bellows have an outer diameter less than 200 mm.Amendments to the Claims have been filed as followsClaims1. A method of manufacturing edge welded bellows, the method comprising the steps of:manufacturing a plurality of convolutions, each convolution within the plurality of convolutions manufactured by:stamping a sheet to form an annular first half convolution with a first shape;stamping a sheet to form an annular second half convolution with a second shape;pairing the first half convolution with the second half convolution, and welding the first half convolution and the second half convolution together around their inner diameters to create a convolution with a central aperture;fitting a spacer to each convolution, wherein the spacer separates the external diameter of the first half convolution from the external diameter of the second half convolution;sorting the convolutions such that the first half convolution of each convolution is adjacent to a second half convolution of another convolution to form a series of convolutions;mounting the series of convolutions on a mounting tool that extends through the central aperture of each convolution;compressing the series of convolutions along the longitudinal axis of the mounting tool such that each convolution is in contact with its adjacent convolutions within the series of convolutions;using an alignment tool to exert radial pressure around the circumference of each convolution within the series of convolutions to radially align each convolution within the series of convolutions;removing the alignment tool;welding each convolution within the series of convolutions to its adjacent convolutions around their external diameter to form an edge welded bellows;wherein the alignment tool is a tapered cylinder.

2. The method of claim 1, wherein the method further comprises removing the edge welded bellows from the mounting tool.

3. The method of claim 1 or claim 2, wherein the method further comprises the step of removing the spacers.

4. The method of any one preceding claim, wherein the method comprises the further step of welding a first flange to a first end of the edge welded bellows.

5. The method of claim 5, wherein the method comprises the further step of welding a second flange to a second end of the edge welded bellows.

6. The method of any one preceding claim, wherein the step of welding each convolution within the series of convolutions to its adjacent convolutions around their external diameter to form an edge welded bellows comprises rotating the series of convolutions.

7. The method of any one preceding claim, wherein the step of welding each convolution within the series of convolutions to its adjacent convolutions around their external diameter to form an edge welded bellows comprises welding each convolution to its neighbouring convolutions in turn.

8. The method of any one preceding claim, wherein the edge welded bellows is leak tested.

9. The method of any one preceding claim, wherein the step of using an alignment tool to exert radial pressure around the circumference of each convolution within the series of convolutions to radially align each convolution within the series of convolutions comprises further compressing the series of convolutions along the longitudinal axis of the mounting tool.

10. The method of any one preceding claim, wherein each first half convolution hasa thickness below or equal to 250 pm.

11. The method of any one preceding claim, wherein each second half convolution has a thickness below or equal to 250 pm.

12. The method of any one preceding claim, wherein the first and / or second half convolution is a metal or alloy.

13. The method of any one preceding claim, where the method comprises the further steps of manufacturing a second edge welded bellows, and then welding the first edge welded bellows to the second edge welded bellows.

14. The method of any one preceding claim, wherein the first shape and the second shape are complementary.

15. The method of any one preceding claim, wherein the first shape and the second shape are identical.

16. The method of any one preceding claim, wherein the process of stamping the first half convolution and / or the second half convolution comprises the use of a rubber insert.

17. The method of any one preceding claim, wherein at least one welding step comprises plasma welding.

18. The method of any one preceding claim, wherein the edge welded bellows have an outer diameter less than 200 mm.

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