Cylinder tube assembly and method for manufacturing the cylinder tube assembly

Abstract

The present invention relates to a cylinder tube assembly comprising a cylinder tube 1 and a connecting piece 2. The cylinder tube 1 comprises a cylinder body and a connecting part 1.3. The connecting part 1.3 comprises an outer shell carrot 3 on the cylinder tube outer shell 1.1, an inner shell carrot 4 on the cylinder tube inner shell 1.2, a structural reinforcement zone and a connecting penetration 5. The carrots 3, 4 are in the form of cold-formed concave embossed parts, the structural reinforcement zone 1.4 is located in the forming area between the carrots 3, 4, the connecting penetration 5 is in the form of a punched hole passing through the carrots 3, 4 and the structural reinforcement zone surrounds the connecting penetration 5. The connecting piece 2 is arranged in the connecting part 1.3 and has a pressure medium tube 6 and a connecting part, which has an annular axial boundary contour 7.1, which together with the annular mating surface 3.1 of the outer shell 3 form an annular touching contact surface, and the cylinder tube 1 and the connecting piece 2 are connected in a material-bonded manner at the annular touching contact surface by an annular welded seam 8, which forms a sealing surface.

Description

[Technical field]

[0001] The present invention relates to a cylinder tube assembly, in particular to the connection of a cylinder tube with a connecting piece, and to a method for the manufacture of a cylinder tube assembly. [Background technology]

[0002] In the prior art, different ways of connecting the connecting piece with the cylinder tube are described: threaded connections are possible, but also material-bonded connections, which are achieved, for example, by welding, are known.

[0003] Threaded connections are often designed such that an internal thread exists on the cylinder tube and a corresponding external thread exists on the connecting piece. The internal thread in the cylinder tube is usually a radial bore hole created perpendicular to the cylinder axis. The disadvantage of this solution is that the threaded area of ​​the cylinder tube must have a minimum thread depth to ensure sufficient mechanical length of the threaded connection. Therefore, the area of ​​the cylinder tube must have a large wall thickness or must be machined in a costly and time-consuming manner. Moreover, a large wall thickness is counterproductive to a material-efficient design.

[0004] In an alternative design, the connecting piece can be welded directly to the cylinder tube. Conventional welding processes such as TIG, MAG or laser welding can be used. In most cases, a filler material is added to fill the joint gap caused by the external curvature of the cylinder tube. Alternatively, milling off the external curvature is also a known process, but this method is disadvantageously associated with a local weakening of the cross section of the cylinder tube. Furthermore, the high heat introduced into the cylinder tube material is also a disadvantage of the mentioned welding process. This results in structural changes that adversely affect the strength. Moreover, there is also a risk of undesired deformation of the cylinder tube in this area.

[0005] Another disadvantage is that the bore holes or threads for the pressure medium connections or pressure medium flows are created by drilling or milling. The resulting cuttings and dust can accumulate inside the cylinder and can contaminate the oil and other surrounding components such as valves or similar components during the subsequent operation of the working cylinder. To avoid this disadvantage, extensive cleaning must be performed.

[0006] Another disadvantage of all known solutions is that the points through which the bore holes reach the inner cylinder wall form contours that either cause increased wear of seals or guides in the piston or that need to be extensively reworked to prevent such undesirable effects. Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to overcome the disadvantages of the prior art by providing a high-quality, robust cylinder tube assembly having a cylinder tube with a connecting piece arranged therein, which can be manufactured in a time-saving and cost-effective manner. [Means for solving the problem]

[0008] With regard to the cylinder tube assembly the problem is solved by the features set forth in claim 1, with regard to the method for the production of a cylinder tube assembly the problem is solved by the features set forth in claim 7. Preferred embodiments result from the corresponding dependent claims.

[0009] The cylinder tube assembly has as its basic components a cylinder tube and a connecting piece.

[0010] A cylinder tube is understood to be any hollow cylinder shell of a hydraulic or pneumatic assembly, preferably the cylinder tube of a hydraulic working cylinder, or the cylinder tube of a hydraulic valve, in particular a hydraulic control valve or a check valve.

[0011] If the cylinder tube is that of a hydraulic cylinder, a piston unit is disposed within the cylinder tube so that it can move axially. A pressure medium is applied to the cylinder tube to effect the movement of the piston unit within the casing. According to the disclosed cylinder tube assembly, the pressure medium is guided laterally in and out through the cylinder tube.

[0012] According to the present invention, the cylinder pipe has a cylinder body and a connection portion.

[0013] A cylinder body is understood to be the basic tubular structure of the cylinder tube.

[0014] The fluid is guided into the pressure medium working chamber formed by the cylinder tube, also known as the cylinder interior, via a connecting part as part of the cylinder tube. The connecting part in turn has an outer shell (calotte) arranged on the cylinder tube outer shell and an inner shell (calotte) arranged on the cylinder tube inner shell. The outer shell (calotte) and the inner shell (calotte) are also collectively called carrots.

[0015] The cylinder-tube assembly according to the invention is particularly characterized in that the carrots are designed as cold-formed concave embossed sections, creating structural reinforcement zones in the forming areas between the carrots.

[0016] From a geometrical point of view, the carrot is designed as a molded part which is concave with respect to the surface contour of the rest of the outer and inner cylinder tube shells, thus forming a recess, and preferably has an elliptical shape.

[0017] The structural reinforcement of the structural reinforcement zone advantageously results in the formation of a mechanically more stable area, where the cylinder tube material has its structure enhanced in a cold forming process as a result of the embossing of the carrot.

[0018] Furthermore, the connecting part has a connecting borehole (through-hole) designed to allow the pressure medium to pass through the cylinder tube, so that, depending on the operating state, said borehole serves as a pressure medium inlet or pressure medium outlet. According to the invention, the connecting borehole is designed as a punched borehole and passes through the two carrots and the cylinder tube located between them. Via the borehole, the working pressure medium can be guided into the cylinder interior.

[0019] The solution according to the invention is furthermore characterized in particular in that the connecting borehole is surrounded by a structural reinforcement zone.

[0020] Thus, the critical area of ​​the pressure medium inlet and the pressure medium connection is provided with greater mechanical strength.

[0021] The connecting piece is arranged in the connecting part and has a pressure medium tube which is designed for the passage of the pressure medium.

[0022] A pressure medium connection of the connecting piece, designed for example as a threaded part, offers the possibility of connecting a pressure medium hose with the connecting piece and indirectly with the cylinder, thus supplying or discharging pressure medium. Depending on the mounting conditions and the operating situation, such a pressure medium hose can be deformed during dynamic movements of the cylinder, thus subjecting the connecting piece to mechanical loads and indirectly to the cylinder tube in areas that are necessarily weakened by the boreholes in any case. A more durable connection option with higher load-bearing capacity is now provided by structural reinforcement.

[0023] Furthermore, the connection part has a connecting portion with an annular axial boundary contour surrounding the pressure medium channel.

[0024] Furthermore, the outer shell carrot also has an annular contour which forms an annular mating surface with the annular axial boundary contour of the connecting piece.

[0025] The annular axial profile according to the invention and the annular mating surface of the outer shell carrot form an annular contact surface which is advantageously practically gap-free. The annular contact and the carrot-shaped embossing allow the connection pieces to be fitted with high tolerances, but still allow a sealing contact. Due to the outer shell carrot designed in particular as a spherical cross section, a practically gap-free annular contact surface is always achieved, even if the connection pieces deviate from the ideal radius relative to the longitudinal axis of the cylinder tube.

[0026] The cylinder tube and the connecting piece are connected to one another at an annular contact surface by an annular weld seam. In the following, the cylinder tube and the connecting piece are also jointly referred to as joint partners. The annular weld seam also forms a sealing surface.

[0027] Furthermore, as a pressure medium passage through the cylinder wall, the pressure medium tube and the connecting bore hole form a common pressure medium channel.

[0028] With the cylinder tube assembly according to the invention, a solution has surprisingly been found which solves many of the problems of the prior art in a technically simple and reliable manner based on advantageous aspects which are explained in more detail below.

[0029] Advantageously, the cylinder-tube assembly according to the invention is obtained by a chip-free production so that no chips are generated that may get inside the cylinder and cause damage, which increases cleanliness and production quality.

[0030] It is also advantageous that burr formation in the connecting bores is prevented by the double-sided embossing. In particular, this eliminates the need for reworking to remove the burrs. Grinding marks that often remain after reworking are also avoided. Advantageously, there are smooth walls in the connecting bores, so that the flow of pressure medium can occur unhindered, uniformly and with low noise.

[0031] In this context, there is also the advantage that, without further measures, the transition between the cylinder inner shell surface and the inner shell carotid is also burr-free due to the embossing. Thus, the point at which the connecting borehole reaches the inner shell carotid is also advantageously slightly recessed radially relative to the contour of the cylinder inner shell surface, so that sensitive components, such as seals or guides on the piston, are particularly protected when passing through the connecting borehole.

[0032] Embossing also results in advantageous structural changes due to material compression in the structural reinforcement zone, i.e. the area around the connecting borehole. This is particularly advantageous in that the connecting borehole would necessarily result in a structural weakening of the cylinder tube wall, which would distribute buckling and axial tensile stresses around the connecting borehole. Furthermore, depending on the application, bending forces may be introduced through the connecting piece. This critical area is strengthened by the advantageous structural changes and can therefore better compensate for the structural weakening caused by the connecting borehole.

[0033] Furthermore, the outer shell carrot advantageously provides an annular mating surface as a contoured surface for flush and gap-free contact of the connecting pieces, thereby creating optimal conditions for a particularly high-quality welded joint without any welding material.

[0034] A further advantage is that the shapes or contours of the outer shell carrot and the inner shell carrot can also differ from each other, so that it is possible to provide special shapes such as a longitudinally extending inner shell carrot which forms a damping pressure medium channel in the cylinder inner shell surface without further steps.

[0035] Furthermore, it is advantageous that the connecting bore holes, the structural reinforcement zone, the annular mating surface of the outer shell carrot and the burr-free passing of the connecting bore holes to the cylinder inner shell surface are performed in just one constant work step, thus enabling cost-effective and efficient production.

[0036] The production of connecting bore holes by punching results in plugs, also called slugs, which can be fully recycled as clean solid scrap. Furthermore, the energy consumption in production for the disclosed punching and embossing process is significantly lower than for the prior art multi-stage machining processes. Also, advantageously, no contaminated cutting waste is generated, which is expensive to dispose of.

[0037] According to an advantageous further development, the cylinder-tube assembly is characterized in that it is designed as part of the working cylinder.

[0038] In a particularly preferred embodiment, this further development is a cylinder assembly for hydraulic actuating cylinders. This cylinder type is subjected to extremely high loads, for which the described advantages of high quality and strength are particularly advantageous. Such actuating cylinders comprise a cylinder tube assembly and a piston unit and are used as primary pressure flow consumers in many application fields.

[0039] According to another advantageous further development, the cylinder tube assembly is characterized in that the annular weld seam is formed as a pressure welded seam.

[0040] Pressure welded seams offer the advantage that the structure in the area surrounding the weld is not altered as much as in other welding processes, especially since the heat introduced into the materials of the weld partners is extremely low.

[0041] The solution according to the invention creates a virtually gap-free contact surface by bringing the annular mating surface of the outer shell carrot into the annular axial boundary contour of the connecting piece, so that an advantageous further development as a pressure welded seam is possible.

[0042] According to a further advantageous development, the cylinder tube assembly is characterized in that the annular weld seam is formed without weld material. The advantage of this development is that no filler material is required for welding.

[0043] Welding can therefore advantageously be carried out with lower energy input, technically simpler and faster, without the generation of weld spatter, and furthermore, no material contamination occurs in the weld joint with added welding material, which can cause corrosion or increased structural distortion.

[0044] According to another advantageous further development, the cylinder-tube assembly is characterized in that the outer shell carrot is designed as a spherical cross section.

[0045] Due to the spherical shape, the structural transition along the cylinder tube wall in the direction of the connecting bore hole as part of the pressure medium channel is a gradual transition which prevents structural cracks, thus avoiding the formation of cracks or dynamic failure.

[0046] The shaping of the carrot shell as a spherical cross section also has the advantage that a circular line can be geometrically inscribed on the surface of the carrot shell, the plane of which can be arranged at various angles so that the connecting pieces can be aligned in a particularly simple manner and a gap-free annular contact surface can always be achieved.

[0047] According to another advantageous further development, the cylinder-tube assembly is characterized in that the inner shell carot is designed as a damping pressure medium channel.

[0048] A further development of this relates to a damping solution in which the piston has a piston ring and the connecting bore hole in the cylinder end region is offset in the axial proximal direction, so that the piston, when approaching the end position, passes over the connecting bore hole with its piston ring and thus encloses the pressure medium volume in the cylinder end region. When the piston passes over the inner shell carrot with its piston ring, the pressure medium channel is not completely closed by the piston. Instead, in the inner shell carrot shaped in this way, a small amount of pressure medium can flow over the piston ring of the piston. Thus, damping of the piston movement can be achieved. The cross section of the damping pressure medium channel determines the degree of damping and its axial extent determines the damping path. In special embodiments, a stepped damping can also be achieved by a cross section with a variable axial extent.

[0049] According to a further aspect of the invention, the cylinder tube assembly is obtained by a manufacturing method which is described in more detail below.

[0050] A method for manufacturing a cylinder tube assembly, characterized in that the cylinder tube assembly is designed according to any one of claims 1 to 6 and comprises the following process steps:

[0051] a) preparing a cylinder tube The starting point of the process is a cylindrical tube, which is obtained from rod material by cutting to length, turning and, if necessary, other work steps.

[0052] The cylindrical tube thus prepared is placed in a device which consists of a press capable of ascending and descending movements and a tool with a defined holder for the tube, so that the tube is always inserted in the same position during serial production and processing always takes place at the same point of the tube.

[0053] b) punching connecting bore holes and forming carrots by using a punching and forming die and an opposing die in a cold forming process. The stamping and forming die has a suitable spherical cross-sectional shape embossing profile and a cylindrical cutting pin that passes through the center of the spherical cross-section. The die also extends beyond the spherical cross-section by at least the length of a single wall thickness of the cylindrical tube.

[0054] In process step b) punching stage, a cutting die contour penetrates into the cylinder tube and punches the connecting bore hole as a cylindrical hole.

[0055] After continued movement of the dies, in the embossing stage, a suitable spherical cross-section embosses the outer carrot shell into the outside of the cylindrical tube. The opposing die provides the reaction force. To do this, it assumes the internal shape of the cylindrical tube. The opposing die also has a suitable spherical convex profile, thus forming the inner carrot shell at the same time that the outer carrot shell is formed. Furthermore, the opposing die passes a cylindrical hole into which the punched cylinder slug and the cutting die cross-section sink.

[0056] During the embossing step, the cutting die, which is still in the connecting bore hole, advantageously supports the inner wall of the connecting bore hole, so that the cylindrical tube material, which plastically forms in the structural reinforcement zone during embossing, is particularly compressed at the inner wall, and at the same time the hole cross section of the connecting bore hole is protected from deformation.

[0057] Furthermore, a further embossing step can be performed with a different embossing tool after process step b) to remove any burrs from the connecting bore holes or to continue shaping the carrots.

[0058] According to a further aspect of the invention, process step b) can also be performed in two sub-steps: in a first sub-step the connecting bore holes are punched by a punching die and in a second sub-step the carrots are embossed by an embossing die, whereby any punching burrs are simultaneously pressed in and thus removed.

[0059] In an advantageous variant, process step b) can also be carried out simultaneously for both pressure medium connections in the case of a cylinder tube which should have two lateral pressure medium connections, one at each end region, so that after this process step a cylinder tube is obtained which has a connection part at one end region and a further connection part at the other end region. For this, the press, in addition to the embossing die and the counter die, in this further development has a further embossing die and a further counter die. Two counter dies are positioned on both lateral sides in the interior of the cylinder tube, where the respective connection parts are to be produced. Both embossing dies can thus be actuated in one press stroke. This applies in particular to cylinder tube assemblies for double-acting actuating cylinders, such as differential cylinders or cylinders with continuous piston rods and therefore two equally large effective surfaces for extension and contraction.

[0060] c) positioning the connecting piece on the outer shell carrot to form an annular contact surface and establish a fixed positional relationship while obtaining a pre-assembly; The connecting piece is positioned in the area of ​​the outer shell carrot with its annular contact surface. Due to the shape of the outer shell carrot in combination with the annular contact surface of the connecting piece, high angular tolerances exist during positioning and fitting. There is always a completely gap-free contact between the joining partner geometries, which results in a homogeneous material bond connection after the next process step.

[0061] d) welding the cylinder tube and the connecting piece, thus creating an annular weld seam. The welding is preferably carried out by pressing the joining partners to create a resistance weld. Welding is used to create a tight material-bonded connection between the cylinder tube and the connecting piece. Furthermore, the connection is impermeable to pressure media. Due to the gap-free prepositioning of the joining partner geometry, the weld can be performed with high quality without the need for costly rework.

[0062] Here, a pressure medium fluid supply in the form of a hose or tube can be attached to the cylinder tube, the connection between the connecting piece and the cylinder tube also providing sufficient resistance to dynamic loads due to pressure surges or hose movements caused by cylinder movements.

[0063] Like process step b), two process steps c) or d) can optionally be performed simultaneously for the two connection portions.

[0064] In an advantageous further development, the process for manufacturing a cylinder-tube assembly is characterized in that in process step b) punching and shaping are performed by means of an opposing die designed as a hardened sphere.

[0065] The opposing die therefore also has a convex area shaped like a spherical cross section, which is embossed on the inside of the cylinder tube, where it also forms a concave carrot.

[0066] By forming an opposing die with hardened spheres, a cost effective embossing tool can be advantageously provided with high process stability.

[0067] According to another advantageous further development, the process for manufacturing a cylinder tube assembly is characterized in that in process step d) the welding is performed as resistance welding.

[0068] The continuous, annular, gap-free support of the connecting pieces in the form of a carrot shell ensures that the supplied energy is distributed evenly. As a result, a precise, fluid-tight weld seam is achieved without the need to introduce additional material.

[0069] The invention will now be explained in more detail by way of an exemplary embodiment with the aid of the accompanying drawings, in which: [Brief description of the drawings]

[0070] [Figure 1] FIG. 2 is a schematic perspective view of a cylinder tube assembly. [Diagram 2] FIG. 2 is a schematic perspective view of a cylinder tube. [Diagram 3] FIG. 2 is a schematic cross-sectional view taken along a cylinder axis. [Figure 4] FIG. 2 is a schematic cross-sectional view perpendicular to the cylinder axis. [Diagram 5] FIG. 2 is a schematic cross-sectional view of a punching and embossing tool. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0071] It should be noted that the same reference numbers in the various figures refer to the same structures or components, and reference numbers are also used herein even if they are not shown in the associated figure.

[0072] Figure 1 shows a schematic perspective view of the entire cylinder tube assembly. In Figure 1, the cylinder tube 1 is connected to a connecting piece 2. In the area of ​​the outer shell carrot 3, the connecting piece 2 is joined in a material-bonded manner by an annular welded seam 8.

[0073] Figure 2 shows a schematic perspective view of a cylinder tube 1 ready for joining, where a spherical cross-sectional shape outer shell carrot 3 is embossed into the outer shell surface of the cylinder tube. Connecting bore holes 5 are also punched for the flow of pressure medium.

[0074] FIG. 3 shows a schematic diagram of the entire cylinder tube assembly cut along the longitudinal axis of the cylinder tube.

[0075] In the area of ​​the connection part 1.3, a spherical cross-sectional profile outer shell 3 is embossed on the cylinder tube outer shell 1.1 into the cylinder tube 1. In contrast, an inner shell 4, also having a spherical cross-sectional profile, is embossed on the cylinder tube inner shell 1.2 into the cylinder tube 1. Depending on the penetration depth, the structure of the cylinder tube material is compressed by a defined amount. This compression results in a local hardening of the material. This is the structure-reinforced zone 1.4.

[0076] At the same time, the connecting bore holes 5 provided for the pressure medium flow are punched out.

[0077] The connecting piece 2 has a pressure medium tube 6 for the passage of pressure medium. Furthermore, the connecting piece 2 has a connecting part 7 with an annular end contour, which is an annular axial boundary contour 7.1. In the joining position, the annular mating surface 3.1 of the outer shell 3 is located opposite this annular axial boundary contour 7.1.

[0078] The connecting piece is placed in the outer shell carrot 3 and is joined in a material-tight manner by an annular weld seam 8, which is produced by pressure welding and also forms a sealing surface for the pressure medium, such that the pressure medium can flow through the connecting piece 2 and the connecting bore hole 5 into the interior of the cylinder tube 1 and vice versa.

[0079] FIG. 4 shows a schematic diagram of the cylinder tube assembly, cut obliquely through the longitudinal axis of the cylinder tube.

[0080] In combination with Fig. 3, Fig. 4 in particular shows the spherical cross-sectional shape contours of the outer shell 3 and the inner shell 4. When the cylinder tube 1 is joined to the connecting piece 2 in process step c), the annular axial boundary contour 7.1 of the connecting piece 2 and the annular mating surface 3.1 as a surface section of the spherical cross-sectional concave surface of the outer shell 3 face each other without a gap. The shape of the outer shell 3 ensures a gap-free sealing contact after welding, even if the joining partners 1, 2 are inclined relative to each other with a large angular deviation.

[0081] During the subsequent pressing in process step d), a uniform energy input and, as a result, a pressure-resistant material bond connection is achieved by the annular weld seam 8. The pressure medium can flow into the interior of the cylinder tube 1 without interference via the connecting bore hole 5 and the downstream inner shell carrot 4.

[0082] FIG. 5 shows a schematic cross-sectional view of a punching and embossing tool for the process of machining the connection section 1.3 of the cylinder tube 1 for the subsequent joining of the connecting piece 2.

[0083] Here, the cylinder tube 1 prepared in process step a) is positioned in the counter die 9.2. In process step b), the die is inserted from the outside of the cylinder tube 1. The punching die 9.1 consists of a cylindrical punching section arranged on a punching section designed as a spherical section. Thus, the connecting bore holes 5 can be punched into the cylinder tube 1 by the punching die 9.1 and the outer carrot shell 3 and the inner carrot shell 4 are embossed simultaneously in the same press stroke.

[0084] In the present exemplary embodiment, the counter die 9.2 also has a spherical cross-section embossing contour, which means that the inner shell carrot 4 can be embossed in the same work step. Furthermore, the counter die 9.2 has a central conical bore hole which receives the punched slug and the cylindrical cross-section of the punch-form die 9.1. With this tool configuration, the entire required joint contour can be created in the cylinder tube 1 in just one press stroke. [Explanation of symbols]

[0085] 1 Cylinder tube 1.1 Cylinder tube outer shell 1.2 Cylinder inner shell 1.3 Connections 1.4 Structural reinforcement zone 2 Connection piece 3. Carrot Shell 3.1 Annular mating surface 4. Inner shell carrot 5 Connection bore hole 6 Pressure medium tube 7 Connection 7.1 Annular Axial Boundary Contour 8 Circular welded seam 9.1 Punching and forming dies 9.2 Opposed dies

Claims

1. A cylinder tube assembly having a cylinder tube (1) and a connecting piece (2), The cylinder tube (1) has a cylinder body and a connecting portion (1.3), The connecting part (1.3) has an outer shell (3), an inner shell (4), a structural reinforcement zone and a connecting bore hole (5), The outer shell carrot (3) is arranged on the cylinder tube outer shell (1.1) and the inner shell carrot (4) is arranged on the cylinder tube inner shell (1.2), the carrots (3, 4) being designed as cold-formed concave embossed profile parts, said structural reinforcement zone (1.4) being located in the moulding area between said carrots (3, 4); the connecting bore (5) is designed as a punched hole for the passage of pressure medium therethrough and passes through the carrots (3, 4), and the structural reinforcement zone surrounds the connecting bore (5), The connecting piece (2) is arranged in the connecting part (1.3) and comprises a pressure medium tube (6) and a coupling part, the pressure medium tube (6) is designed for the pressure medium passage of the pressure medium, The connecting portion has an annular axial boundary contour (7.1), said annular axial boundary contour (7.1) and an annular mating surface (3.1) of said outer shell (3) form an annular contact surface; A cylinder tube assembly, wherein the cylinder tube (1) and the connecting piece (2) are connected in a material-bonded manner at the annular contact surface by an annular weld seam (8), the annular weld seam (8) forming a sealing surface, and the pressure medium tube (6) and the connecting bore hole (5) form a common pressure medium channel.

2. 2. A cylinder tube assembly according to claim 1, characterized in that the cylinder tube assembly is designed as a part of a working cylinder.

3. 3. A cylinder tube assembly according to claim 1 or 2, characterized in that the annular welded seam is formed as a pressure welded seam.

4. 4. A cylinder tube assembly according to claim 1, wherein the annular weld seam is formed without welding material.

5. 5. A cylinder-tube assembly according to claim 1, characterized in that the outer shell (3) is designed with a spherical cross section.

6. 6. Cylinder tube assembly according to claim 1, characterized in that the inner shell carrot (4) is designed as a damping pressure medium channel.

7. 1. A method of manufacturing a cylinder tube assembly, comprising the steps of: The cylinder tube assembly is designed according to any one of claims 1 to 6 and is produced by the following process steps: a) providing said cylindrical tube (1); b) punching out the connecting bore holes (5) and forming the carrots by using a punching and forming die (9.1) and an opposing die (9.2) in a cold forming process; c) positioning the connecting piece (2) on the outer shell carrot (3) and establishing a fixed positional relationship and forming the annular contact surface to obtain a pre-assembly; d) welding the cylinder tube (1) and the connecting piece (2) together to create the annular weld seam (8); 1. A method for manufacturing a cylinder tube assembly, comprising:

8. 8. Method for manufacturing a cylinder-tube assembly according to claim 7, characterized in that in process step b) punching and forming are carried out by means of opposing dies (9.2) designed as hardened spheres.

9. 9. Method for manufacturing a cylinder tube assembly according to claim 7 or 8, characterized in that in process step d), the welding is performed as resistance welding.

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