DE102019007820A1 - Device for leveling a weld - Google Patents

Abstract

The invention relates to a device (11) for leveling a weld seam (10) between an inner container (4) and a connection piece (2) inside a Type IV compressed gas container (1), with a drive device (12) for a tool (13 ). The device according to the invention is characterized in that the tool (13) is designed to be rotatable relative to the pressurized gas container (1), the tool (13) having a shaft (14) which has a smaller diameter than a central connection opening (17) of the connection piece ( 2, 3), wherein at one end of the shaft (14) a tool arm (15) is pivotally mounted, which has at least one cutting edge (16) and which can be arranged in alignment with the shaft (14), and the diameter the connection opening (17) does not exceed, and which is pivotable eccentrically to the shaft (14) in a working position.

Description

The invention relates to a device for leveling a weld in a type IV compressed gas container according to the type defined in the preamble of claim 1.

So-called type IV compressed gas containers are so far known from the prior art. It is characteristic of this type of pressurized gas container that it has an inner container made of plastic, a so-called liner or inner liner, which is connected directly or typically indirectly via an intermediate element to a connector, the so-called boss. For example, the inner container can be welded to the connection piece and / or can be pressed by mechanical elements. Such a structure is for example from the DE 10 2006 031 118 A1 known. Furthermore, such a type IV compressed gas container comprises an outer shell or support shell which is constructed from one or more layers of fiber-reinforced plastic to absorb the mechanical forces.

In practice, it is now the case that the transition from the inner container to the connecting piece, and here in particular the area of the weld seam, is relatively susceptible with regard to the permanent mechanical load, in particular when subjected to pressure changes. The above DE 10 2006 031 118 A1 therefore goes the way to move the weld seam relatively far outwards in the area of a connection opening and to support it with an additional body that presses the inner shell with the connection piece.

Other variants such as the one in the DE 10 2009 049 948 A1 mentioned construction go the way that they weld the inner container with an intermediate layer or an intermediate element, which in turn is then connected to the actual connector.

In practice, it is difficult to achieve a high level of robustness and fatigue strength in the area of the connection for all structures.

The object of the present invention is therefore to provide a device which makes it possible to increase the robustness and fatigue strength of the pressurized gas container, in particular in the event of pressure changes, compared to the structures from the prior art.

According to the invention, this object is achieved by the device with the features in claim 1. Advantageous refinements and developments result from the dependent claims dependent thereon.

A connection of the inner container to a connecting piece by direct or indirect welding of the two is provided in the compressed gas container. In practice it is now the case that the welding, usually an indirect shedding between the inner container made of plastic and a plastic coating on the connection piece, creates a welding gap through the melted material, from which this material is displaced, and that a welding bead or weld seam forms, which typically has areas protruding into the interior of the pressurized gas container.

The device according to the invention now comprises a tool with a shank which has a smaller diameter than a central opening of the connection piece. A tool arm, which has at least one sheath, is also pivotably mounted at one end of the shaft. The tool arm is arranged in an insertion position in alignment with the shaft and does not exceed the diameter of the opening of the connection piece. It can therefore be inserted into the interior of the pressurized gas container through the opening in the connector. The tool arm also includes a working position in which the tool arm is arranged eccentrically to the shaft. In this working position, it can be pivoted in particular about a common axis of rotation between the shank and the tool arm, which in turn is preferably arranged centrally with respect to the width of the shank. The tool can therefore be inserted into the compressed gas container in the insertion position. If the tool arm with the cutting edge is then pivoted into the second eccentric working position, then according to the structural design of the tool arm, the cutting edge can engage with circumferential regions which are concentric about the rotation when the compressed gas container is rotated around the tool or the tool in the compressed gas container is rotated Axis of rotation are arranged.

It is precisely in this area, in which the tool of the device according to the invention can now engage, that the weld seam with the protruding areas mentioned above is located, which leads to the increased notch effect and is therefore undesirable with regard to the stability of the structure. Via the drive device of the tool, which, for example, drives the tool in a rotating manner or holds it accordingly, if the compressed gas container itself rotates, the tool can now also be appropriately delivered in order to remove the protruding areas of the weld seam. The delivery is preferably carried out in several small steps in order to produce correspondingly short and small chips, which can be easily removed from the inside of the compressed gas container.

By using the device according to the invention with its tool, the weld seam is thus equalized in order to avoid any notch effect emanating from the weld seam. This smoothing of the area of the weld seam creates a stable structure which is by no means as sensitive in the area of the potential weak point as the structures according to the prior art. By leveling the weld seam, a very robust and dense construction of the compressed gas tank can be achieved even over a long operating period. In particular in the case of pressure fluctuations which occur again and again, as frequently occur, for example, when using such pressurized gas containers as hydrogen tanks in the vehicle, the method according to the invention has decisive advantages.

According to a very advantageous development of the idea, it can further be provided that the tool arm can be locked in the second working position. This locking in the second working position ensures an exactly reproducible position of the tool arm and thus of the cutting edge, so that despite the external delivery of the tool via the drive device, clean, reliable and reproducible machining of the area of the weld seam is possible.

In particular, the locking can take place via an adjusting element, in particular a screw, on the shank of the tool and thus thus from the outside.

The cutting edge itself can preferably be designed as an exchangeable cutting insert, so that it can be easily replaced when worn, without the structure having to be newly realized and laboriously measured. Particularly suitable as an exchangeable cutting insert is a cutting insert or interchangeable cutting edge, as is generally known, for example, in the field of milling or turning.

Further advantageous configurations of the device according to the invention also result from the exemplary embodiment, which is explained below by way of example and is described with reference to the figures.

• 1 eine schematische Ansicht eines Druckgasbehälters;
• 2 eine Schnittdarstellung durch einen Teil des Druckgasbehälters nach dem Verschweißen des Innenbehälters mit dem Anschlussstück;
• 3 eine Zeichnung und eine Röntgenaufnahme eines Ausschnitts aus 2 in einer Vergrößerung;
• 4 einen Teil des Druckgasbehälters mit der erfindungsgemäßen Vorrichtung in einer ersten Einführposition;
• 5 Darstellung analog zu der in 4 in einer zweiten Arbeitsposition der Vorrichtung; und
• 6 Analog zu den Darstellungen in 3 eine zeichnerische Darstellung und eine Röntgenaufnahme des durch eine Bearbeitung mit dem Werkzeug erzielbaren Ergebnisses.

Show:

• 1 a schematic view of a pressurized gas container;
• 2nd a sectional view through part of the pressurized gas container after welding the inner container to the connector;
• 3rd a drawing and an x-ray of a detail 2nd in an enlargement;
• 4th a part of the compressed gas container with the device according to the invention in a first insertion position;
• 5 Representation analogous to that in 4th in a second working position of the device; and
• 6 Analogous to the representations in 3rd a graphic representation and an X-ray of the result that can be achieved by machining with the tool.

In the representation of the 1 is a type IV compressed gas tank 1 shown schematically. It essentially comprises a cylindrical central section and two semicircular end areas, which are also referred to as domes. In this area there are connectors 2nd , 3rd arranged which are also referred to as BOSS. The construction of a typical type IV compressed gas container 1 it now provides for the partial cut of the 2nd it can be seen that an inner container 4th made of plastic, a so-called liner is formed, which ensures tightness against the gas to be stored, for example hydrogen. This is with the connector 2nd in the representation of the 2nd connected, in the case shown here with a partial plastic covering 6 of the connector 2nd welded. This partially plastic wrap 6 , which is also known as BOSS Overmold, is form-fitting and / or glued to the connector 2nd connected, for example in which the connector 2nd and the depressions provided there are partially extrusion-coated. An outer shell then surrounds this entire structure 5 Made of a fiber-reinforced plastic material, which absorbs the mechanical load, without even for that in the compressed gas container 1 stored gas to be tight or to be tight. In addition there are reinforcement pieces or compensating pieces 7 arranged in the area of the dome or your shoulders in order to reinforce the structure accordingly in this area and to make it easier to take up in storage. This structure is known in principle from the prior art.

The inner container 4th has, as in the enlarged view of section III in 2nd you can see a stabilizing ring 8th of the inner container 4th made of plastic. In the representation of the 3rd on the left is the area in which the plastic covering 6 with the inner container 4th is welded, marked by a dashed line and with the reference symbol 9 Mistake. This area of welding is in the 3rd on the right again in an X-ray image, here the material of the plastic covering 6 darker than the material of the inner container 4th is shown. Clear it can be seen that the welding and the resulting liquefaction of the material result in a squeezed weld bead 10th from the material of the plastic covering 6 and / or the material of the inner container 4th arises. Overall, there is a weld seam or weld bead here 10th , which is raised in relation to the material in the environment and thus carries the massive risk of a notch effect.

This notch endangers the stability of the connection between the inner container 4th and over the plastic wrap 6 indirectly with the connector 2nd , so that a failure of either the connection or the areas surrounding the connection can occur very quickly under high load, in particular with a high cyclical load. To counteract this problem, the protruding material areas of the welding bead should 10th and ideally also the stabilization ring 8th , if it exists, be removed. Because at this point at least the connector 2nd already indirectly with the inner container 4th of the compressed gas tank 1 is welded, you must now work inside the body, either on the intermediate product from the inner container 4th and connector 2nd or on the finished pressurized gas container 1 after this the outer shell 5 and, if necessary, the reinforcement pieces 7 had received. In order to be able to implement this, there is a special device 11 provided which in the representation of the 4th is shown in an insertion position. The device 11 consists essentially of a drive device 12th as well as a tool 13 which has a shaft 14 and one opposite the shaft 14 swiveling tool arm 15 with one cutting edge 16 , for example an exchangeable cutting edge. Both the shaft 14 as well as the tool arm 15 with the cutting edge 16 have a diameter in this insertion position which is capable of streaking through the narrowest part of a connection opening 17th of the connector 2nd drive through. In the representation of the 4th the first insertion position is pulled through into the connection opening 17th retracted tool arm 15 to recognize, and in the position shown in dashed lines a second insertion position of the body with already in the interior of the compressed gas container 1 moved tool arm 15 .

In the representation of the 5 is now the working position of the device 11 or the tool 13 shown. The tool arm 15 is eccentric to the shaft 14 pivoted so that the cutting edge 16 in the area of connection 9 between the plastic wrapping 6 and the inner shell 4th comes to rest. Now, for example, via the drive device 12th the shaft 14 set in a rotational movement or held accordingly and the pressure vessel 1 set in a rotational movement, the cutting edge 16 the unwanted material of the welding bead in the manner of a turning or milling process 10th and the stabilization ring 8th from. It can by the drive device 12th a corresponding feed in the direction of the connector 2nd to be set. In particular, the adjustment takes place in correspondingly small feed steps, so that relatively small and therefore short chips result, which break correspondingly early and, in contrast to long unbroken chips, are much easier to get from the inside of the compressed gas container 1 are to be removed. The chips can, for example, through a suction pipe, which through a connection opening, not shown here, of the opposite connection piece 3rd is suctioned off. Alternatively or in addition, cleaning can also be carried out using compressed air after the end of the mechanical cutting process using the tool 13 respectively. In addition, a camera can be used, for example, via the connector 3rd is inserted together with a suction pipe, or which after processing through the connection opening 17th is introduced, the success of the mechanical processing is monitored and, if necessary, documented.

In practice, it now looks that the result of the processing roughly corresponds to that in the representation of the 6 shown geometry leads. In the 6 left is again analogous to the representation in 3rd on the left, the construction of a part of the connector 2nd with the plastic covering 6 and the inner container welded to it 4th to recognize. The welding bead 10th and the stabilization ring 8th are through the tool 13 have been completely removed here, so that an ideal continuous transition is created, which is smoothed accordingly and thus eliminates the risk of a potential notch effect. In the representation of the 6 on the right, the roughly the same section can be seen again in an X-ray, so that it can be seen that the representation is not idealized, but also goes hand in hand with a comparable quality of the geometry obtained. The connection between the inner liner and the connection piece achieved by welding in this way 2nd or its plastic casing 6 reworked compressed gas tank 1 thus enable a much higher load capacity and are extremely durable even with frequent pressure changes, such as those that can occur in vehicle applications. They are therefore particularly suitable for storing hydrogen at a nominal pressure of 70 MPa, as can be used, for example, in vehicles for use with a fuel cell drive system.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102006031118 A1 [0002, 0003]
• DE 102009049948 A1 [0004]

Claims (4)

Device (11) for leveling a weld seam (10) between an inner container (4) and a connecting piece (2) inside a Type IV compressed gas container (1), with a drive device (12) for a tool (13), characterized that the tool (13) is designed to be rotatable relative to the compressed gas container (1), the tool (13) having a shaft (14) which has a smaller diameter than a central connection opening (17) of the connection piece (2, 3), wherein at one end of the shaft (14) a tool arm (15) is pivotally mounted, which has at least one cutting edge (16) and which can be arranged in alignment with the shaft (14), and the diameter of the connection opening (17) is not exceeds, and which can be pivoted eccentrically to the shaft (14) in a working position. Device (11) after Claim 1 , characterized in that the tool arm (15) can be locked in the second working position. Device (11) after Claim 2 , characterized in that the locking can be realized via an adjusting element, in particular a screw, on the end of the shaft (14) facing away from the tool arm (15). Device (11) after Claim 1 , 2nd or 3rd , characterized in that the cutting edge (16) is designed as an exchangeable cutting insert.

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