Forming device for pipe sections to be welded together

Abstract

The invention relates to a forming device for pipe sections (1) to be welded together, comprising at least two forming bladders (2) which can be inflated via a filling line (3), a flushing line (4) for supplying a flushing chamber (5), which is defined between the forming bladders (2), with flushing gas, and a gas outlet (6) for discharging a gas located in the flushing chamber. In order to improve such a forming device with respect to the flushing quality and performance, the invention proposes that the two forming bladders (2) have at least one connectable connection (7) for releasably connecting the flushing line (4), which opens into flushing chamber (5), and at least one closable gas outlet (6).

Description

[0001]Forming device for pipe sections to be welded together. Technical field: The invention relates to a forming device for pipe sections to be welded together, comprising at least two forming bladders that can be inflated via a filling line, a purge line for supplying purge gas to a purge chamber spanned between the forming bladders, and a gas outlet for discharging a gas located in the purge chamber. Both forming bladders have at least one closable gas outlet. A forming device is used when welding two pipe sections together to protect the weld root from oxidation and scaling. Various forming devices are available for this purpose.State of the art A forming device mentioned above for pipe sections to be welded together, comprising two forming bladders that can be inflated via a filling line, with a purging line for supplying a purging chamber spanned between the forming bladders with purging gas and with a gas outlet for discharging a gas located in the purging chamber, is disclosed, for example, in GB 2383108 A. Other generic devices are known from WO 2005084870 A1 and KR 20100011238 A. The "Purge Star" forming device from Holzer-ASS® has inflatable forming bladders for this purpose, each of which is inserted into a pipe section in such a way that the joint of the pipe sections to be welded is arranged between the forming bladders. By inflating the forming bladders via a filling line, they are pressed against the inner wall of the pipe sections, so that the forming bladders form a seal.A purging chamber is thus created between the inflated forming bladders, which is defined on the end section side by the forming bladders and on the shell side by the pipe sections. One forming bladder has a purge line for purge gas and a gas outlet, while the other forming bladder serves merely as a seal. The purge line supplies the purge chamber with a purge gas, such as argon, or forming gas, and at the same time, the gas in the purge chamber, in particular oxygen, is expelled or flushed out via the gas outlet located in the area of ​​the purge line connection. Although this forming device can sufficiently expel the air atmosphere in the purge chamber for standard applications, tests have shown that the required purge time is relatively long.Furthermore, for certain pipe systems to be welded, specifications arise as to the direction in which the gas expelled from the purging chamber must be discharged, which complicates the correct arrangement of the forming bladders and requires special designs for certain pipe systems. Description of the invention The invention is therefore based on the object of proposing a forming device of the type mentioned at the outset that allows both flexible use with different pipe systems and offers the possibility of a faster purging process without compromising weld root protection. The invention achieves this object in that both forming bladders have at least one closable connection for detachably connecting the purging line leading into the purging chamber.As a result of the measures according to the invention, both forming bladders can be used equally to supply the purge chamber with a purge gas, for example, argon or forming gas, and both forming bladders can be used equally to discharge the gas present in the purge chamber, in particular the oxygen. Specifically, each forming bladder has, in addition to a flow connection to a filling line through which the forming bladders can be inflated, at least two lines, one line containing the gas outlet and one line containing the connection for the purge line. This results in a multitude of different possible applications and circuit configurations.In a first application, the backflushing circuit, the connection for the purge line and the gas outlet can be closed in one purge bladder, which in this case only serves as a seal, so that the entire purge process takes place via the connected purge line and the open gas outlet of the other purge bladder. In a second application, the flushing circuit, the purge line can be connected to one purge bladder, while the gas outlet of this purge bladder is closed. The other purge bladder, on the other hand, has an open gas outlet and a closed connection for the purge line. In this way, the purge gas is applied via one purge bladder and the gas is discharged via the other purge bladder.Surprisingly, it has been found that this second application option allows significantly lower residual oxygen levels to be achieved in the purge chamber, making it particularly suitable for use with this type of circuit when welding pipes used in the food and pharmaceutical industries. A particularly short purge time is achieved with a third application option, the high-volume flow purge circuit. In this case, the purge line can be connected to one purge bladder, while the gas outlet of this purge bladder is closed, and the other purge bladder has an open gas outlet and an open connection for the purge line. In this way, both the connection for the purge line and the gas outlet function as lines through which the gas can be expelled from the purge chamber.In this way, the purging chamber can be supplied with much higher volume flows, so that the purging time can be significantly reduced. In the simplest case, the connection of the purging line and the gas outlet can be closed off using a sealing plug. Alternatively, valves can also be used for closing. If the device according to the invention is to be used for forming, the forming bladders are each inserted into a pipe section in such a way that the joint of the pipe sections to be welded is arranged between the forming bladders, after which the forming bladders are inflated via the filling line in such a way that they are pressed against the inner wall of the pipe sections to form a seal. Each forming bladder can be assigned its own filling line to inflate the forming bladders.Particularly simple constructionally, however, results when the forming bladders are fluidly connected to one another via a common, preferably detachable filling line. In this way, the inflation process of both forming bladders can take place via a filling gas supply line arranged on one side, which is connected to one forming bladder, since the other forming bladder is also supplied with the filling gas, e.g. air, forming gas, or argon, via the common filling line. A purging chamber is thus created between the inflated forming bladders, which is delimited on the end section side by the forming bladders and on the shell side by the pipe sections. Typically, the joint between the pipe sections is sealed from the outside with a sealing tape, so that the purging chamber is sealed except for the gas outlet.Purge gas is then introduced via the purge line and, after a specific purge time, the welding process is carried out. The sealing tape is gradually removed before the exposed joint section is welded together. The purge gas atmosphere in the purge chamber prevents oxidation of the weld root. In order to make changing between the different applications, in particular the connections, as easy as possible, the connection for the purge line and the gas outlet can be of identical design. This means that no adapter or similar is necessary if, for example, the forming device is converted from the previously mentioned backflushing circuit to the purge circuit, since the same closures can be used for the connection and the gas outlet. In addition, there is flexibility in the arrangement of the purge line leading into the purge chamber on the forming bladder.A structurally particularly simple forming device is obtained when both forming bladders are penetrated by a bladder core having at least three lines running in the direction of the bladder core's longitudinal axis, with one line for each bladder core being fluidly connected to the filling line and the other lines being optionally connected to the purge line, forming the gas outlet, or being closed. The lines not connected to the filling line can therefore fulfil different functions. When the purge line is connected, they can form the connection for the purge line; when the purge line is not connected, they can either be closed or form the gas outlet. Particularly when the three lines are of identical construction and run parallel to one another, particularly flexible interconnection is achieved.To increase the volume flow rate and thus reduce the purging time, the bladder core can have four or more lines running in the direction of the bladder core's longitudinal axis, preferably parallel. To ensure that the forming bladders can be inflated in a structurally simple manner, it is proposed that the line fluidically connected to the filling line have radially extending branch lines for inflating the forming bladder. The forming bladder can thus be clamped onto the bladder core on the shell side and connected to it in a flow-tight manner, so that the branch lines conduct the filling gas from the filling line or from a filling gas supply line into the interior of the forming bladder. The other lines of the bladder core are not fluidly connected to the interior of the bladder core.In order to be able to flexibly design not only the supply of gas to the purging chamber, but also the inflation of the forming bladders, both forming bladders can have a closable purge gas supply connection for a purge gas supply line and a closable filling gas supply connection for a filling gas supply line. Thus, especially when the forming bladders are fluidly connected to one another via a common filling line, inflation can take place from both sides of the forming bladder. The purge gas supply connection and the filling gas supply connection are preferably arranged on the side of the forming bladders facing away from the purge chamber. The purge gas supply connection is preferably formed by the opposite end section of that line of the bladder core whose end section facing the purge chamber forms the connection for the purge line.The filling gas supply connection is preferably formed by the end section of the bladder core line having branch lines facing away from the purge chamber. Preferably, the bladder cores of both forming bladders and / or the forming bladders themselves can be identical parts. This means that these components are structurally identical and thus each have all connections, lines, and gas outlets, which further increases the flexibility of the forming device. In use, the bladder cores and / or the forming bladders differ only in the differently connected components or closures. Particularly good results with regard to a low residual oxygen content have been achieved by having the purge line leading into the purge chamber have a diffuser through which a filling line runs through the purge chamber and connects the forming bladders to one another.The diffuser, which comprises, for example, a sintered metal and is connected to the end section of the purge line, ensures that the purge chamber is evenly supplied with the purge gas. Because the diffuser simultaneously accommodates the filling line, which runs particularly in the region of the forming bladder's longitudinal axis, it is supported by the filling line, so that the diffuser is essentially equally spaced radially from the walls of the pipe sections in all directions. The diffuser is thus arranged centrally in the purge chamber in the radial direction, which promotes even distribution of the purge gas in the purge chamber. Surprisingly, it has been found that the residual oxygen content in the purge chamber can be further reduced by two measures. Firstly, a throttle can be provided downstream of the gas outlet. This throttle can in turn comprise a sintered metal.Alternatively, the purge bags can be encased in a neoprene jacket, which improves the sealing effect of the purge bag against the pipe section and reduces the tendency to wrinkle. It has been shown that both unrelated measures promote an enrichment of the purge gas in the purge chamber and thus a reduction in oxygen. In the pharmaceutical and food industries, the "weld discoloration level"—i.e., the discoloration of the weld root—is regularly used to monitor the oxidation of the weld roots. The more severe the discoloration, the less favorable, as this represents a growth potential for microorganisms.It has been found that, on the one hand, results accepted by the food and pharmaceutical industries and, on the other hand, a rapid purging time can be achieved when the purge gas flows into the purge chamber at a volume flow of 20-45 L / min, preferably 25-40 L / min, and in particular at a volume flow of 28-37 L / min. In this volume flow range, a pulse-like expansion of the purge gas occurs in the purge chamber, which particularly effectively expels a large portion of the gas - the air - present in the purge chamber at the beginning of the purge process. While volume flows below the proposed range result in severe discoloration in the area of ​​the weld root, which promotes undesirable microbial growth, higher volume flows lead to hardly any improvement in terms of residual oxygen content, but merely to increased resource consumption.In particular, the purge circuit in which the purge gas flows in via one forming bladder and the gas in the purge chamber flows out via the other forming bladder has shown the best results. A volume flow of 30-35 L / min produces a particularly effective purge pulse. The purge pulse can advantageously cause pressure fluctuation-induced suction effects in the gas outlet, which further promotes the rapid expulsion of oxygen from the purge chamber and, with such a volume flow with the forming device according to the invention, reduces the residual oxygen content in the purge chamber to 6 ppm. Brief description of the invention The subject matter of the invention is illustrated by way of example in the drawing. Fig. 1 shows a schematic section through a forming bladder of a forming device according to the invention, Fig. 2 shows a section along the line II-II of Fig. 1 on the same scale, Fig. 3 shows a forming device according to the invention in a purge circuit, Fig.4 shows a forming device according to the invention in a backflushing circuit, Fig. 5 shows a forming device according to the invention with three forming bladders in a flushing circuit, Fig. 6 shows a forming bladder of a forming device according to the invention in a pipe end section in a backflushing circuit and Fig. 7 shows a diffuser of a forming device according to the invention. Ways of carrying out the invention A forming device according to the invention for pipe sections 1 to be welded together has, as can be seen for example in Figs. 3-5, at least two forming bladders 2 which can be inflated via a filling line 3. Although each forming bladder 2 can have its own filling line 3, particularly simple construction conditions result if the forming bladders 2 are fluidly connected to one another via a common filling line 3, as is the case in Figs. 3 and 4.In addition, the forming device, which can also be called a forming device, has a purging line 4 for supplying purging gas to a purging chamber 5 spanned between the forming bladders 2. As can be seen from Figs. 3 to 5, the purging chamber 5 can be delimited on the end section side by the inflated forming bladders 2 and on the shell side by the pipe sections 1. After the start of the purging process, the gas in the purging chamber 5 is displaced by the purging gas and purged out via a gas outlet 6, which is assigned to a forming bladder 2. According to the invention, both forming bladders 2 have at least one closable connection 7 for detachably connecting the purging line 4 opening into the purging chamber 5 and at least one closable gas outlet 6. In this way, the forming device can be used in different circuits. Fig.3 shows a purging circuit in which the purge gas is introduced via the connection 7 for the purge line 4 of the right forming bladder 2 and the gas is discharged from the purge chamber via the gas outlet 6 of the left, i.e. the other, forming bladder 2. For this purpose, the gas outlet 6 of the right forming bladder and the connection 7 for the purge line 4 of the left forming bladder 2 are closed. Fig. 4 shows a backflushing circuit in which the purge gas is introduced via the connection 7 for the purge line 4 of the right forming bladder 2 and the gas is discharged from the purge chamber 5 via the gas outlet 6, also of the right, i.e. the same, forming bladder 2. For this purpose, the gas outlet 6 and the connection 7 for the purge line 4 of the left forming bladder 2 are closed. The closure can be achieved using simple sealing plugs 8. As can be seen in particular in Figs.1 and 2, the connection 7 for the purge line 4 and the gas outlet 6 can be constructed identically, so that both components have both functions and thus the connection 7 can also function as a gas outlet 6 and vice versa. Fig. 1 shows that the forming bladders 2 can be penetrated by a bladder core 9, for example made of plastic. The bladder core 9 can have at least three, preferably four lines 11a, b, c, d running in the direction of the bladder core longitudinal axis 10. One line 11a can be fluidly connected to the filling line 3. The other lines 11b, c, d can optionally be connected to the purge line 4, form the gas outlet 6, or be closed. The lines 11b, c, d can thus form the connection 7 and / or the gas outlets 6.The three lines 11b, c, d can be of identical construction, which further facilitates the optional connection to the purge line 4, the formation of the gas outlet 6, and the closure, for example, via identical sealing plugs 8. To inflate the forming bladders 2, the line 11a, which is connected to the filling line 3, can have radially extending branch lines 12. Referring to Figs. 1-6, both or all of the forming bladders 2 can have their own purge gas supply connection 13 for a purge gas supply line 14 and a filling gas supply connection 15 for a filling gas supply line 16. The purge gas supply connection 13 and the filling gas supply connection 15 can be closable, for example, via a sealing plug 8. The purge gas supply connection 13 and the filling gas supply connection 15 can be of identical construction.The filling gas supply connection 15 can be formed by the end section of the line 11a facing away from the rinsing chamber. The purge gas supply connection 13 can be formed by the end section of the lines 11b, 11c, 11d facing away from the rinsing chamber. In particular, the bladder cores 9 of both forming bladders 2 and / or the forming bladders 2 can be identical parts, which further facilitates the exchange of various supply lines, closures, and other components and increases the flexibility of use of the forming device. Identical parts means that the components are structurally identical. For example, from Fig. 5, which shows a variant with three forming bladders 2, it can be seen that the purge line 4 has a diffuser 17. The diffuser 17 can be penetrated without any flow connection by the filling line 3, which runs through the rinsing chamber 5 and connects the forming bladders 2 to one another.There is therefore no flow connection between the filling line 3 and the diffuser 17. As a result of these measures, the diffuser 17 can be carried by the filling line and thus arranged centrally in the pipe section in the radial direction. The diffuser 17 can be seen in more detail in Fig. 7. This can be formed by a sintered metal 18 connected to the purge line 4 and optionally with radially arranged openings 19, wherein the sintered metal 18 is enclosed by a distributor drum 21 having holes 20, wherein the holes 20 are preferably assigned to both the drum shell and the cover sides. This makes it possible to achieve a purge gas flow that spreads essentially spherically around the distributor drum 21. The diffuser 17 can have a through-pipe to accommodate the filling line 3. In Fig. 7, the filling line 3 runs on the axis of the distributor drum 21 and the purge line 4 is spaced radially from the axis of the distributor drum 21.The arrangement of the filling line 3 and the purge line 4 can also be reversed. Figures 3-6 show that a throttle 22 can be provided downstream of the gas outlet 6. The throttle 22 can in turn be formed by a diffuser. The jacket 23 of the forming bladders 2 can be made of neoprene.

Claims

Patent claims 1. Forming device for pipe sections (1) to be welded together, comprising at least two forming bladders (2) inflatable via a filling line (3), a purge line (4) for supplying purge gas to a purge chamber (5) defined between the forming bladders (2), and a gas outlet (6) for discharging a gas located in the purge chamber, wherein both forming bladders (2) have at least one closable gas outlet (6), characterized in that both forming bladders (2) have at least one closable connection (7) for releasably connecting the purge line (4) opening into the purge chamber (5).

2. Forming device according to claim 1, characterized in that the connection (7) for the purge line (4) and the gas outlet (7) are of identical construction. 3.Forming device according to claim 1 or 2, characterized in that both forming bladders (2) are penetrated by a bladder core (9) having at least three lines (11a, b, c) running in the direction of the bladder core longitudinal axis (10), wherein one line (11a) for each bladder core (9) is fluidically connected to the filling line (3) and the other lines (11b, c) are optionally connected to the flushing line (4), form the gas outlet (6), or are closed.

4. Forming device according to claim 3, characterized in that the bladder core (9) has four lines (11a, b, c, d) running in the direction of the bladder core longitudinal axis (10).

5. Forming device according to claim 3 or 4, in that the line (11a) fluidly connected to the filling line (3) has radially extending branch lines (12) for inflating the forming bladder (2).

6. Forming device according to claim 4 or 5, characterized in that three lines (11b, c, d) are identically constructed for each bladder core (9) and can be optionally connected to the purge line (4), form the gas outlet (6), or are closable.

7. Forming device according to one of claims 1 to 6, characterized in that both forming bladders (2) have a closable purge gas supply connection (13) for a purge gas supply line (14) and a closable filling gas supply connection (15) for a filling gas supply line (16).

8. Forming device according to one of claims 1 to 7, characterized in that the bladder cores (9) of both forming bladders (2) and / or the forming bladders (2) are identical parts. 9.Forming device according to one of claims 1 to 8, characterized in that the flushing line (4) opening into the flushing chamber (5) has a diffuser (17) through which a filling line (3) runs through the flushing chamber (5) and connects the forming bladders (2) to one another.

10. Forming device according to one of claims 1 to 9, characterized in that a throttle (22) is provided downstream of the gas outlet (6).

11. Forming device according to one of claims 1 to 10, characterized in that the forming bladders (2) have a jacket (23) made of neoprene.

12. Method for forming pipe sections to be welded together using a forming device according to one of claims 1 to 11, characterized in that the flushing gas is supplied at a volume flow of 20-45. L / min, preferably 25-40 L / min, in particular with a volume flow of 28-37 L / min into the rinsing chamber (5).

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