Actuating cylinder

Abstract

The invention relates to a cylinder 1 having a cylinder tube 3, a closure member 4a and a further closure member 4b, the closure member 4a being arranged at one cylinder tube end 5a and the further closure member 4b being arranged at the other cylinder tube end 5b, the closure member 4a having an axial portion 4a.1, the cylinder tube 3 having a cylinder tube end portion 5a.1, the axial portion 4a.1 and the cylinder tube end portion 5a.1 forming a connection section 7a, in which the closure member 4a is arranged at the axial portion 4a.1 of the cylinder tube 3 and the cylinder tube end portion 5a. 1, the coupling section having a proximal section 7a.1 and a distal section 7a.2, the axial portion 4a.1 being tapered, the axial portion 4a.1 having at least partially oversized dimensions relative to the inner diameter of the cylinder tube 3, the cylinder tube 3 having an elastic circumferential expansion therein, the coupling section 7a being designed for an axial force- and form-fitting of the closure member 4a and the cylinder tube 3, the cylinder tube end 5a being bonded integrally to the closure member 4a by a circumferential ring weld seam 8a in the form of a laser welded seam and forming a pressure-medium-tight sealing surface.

Description

Technical Field

[0001] The present invention relates to an operating cylinder, particularly a hydraulic operating cylinder, and a method for manufacturing the same.

Background Art

[0002] Such operating cylinders are known from the prior art. Usually, these operating cylinders have a cylinder tube and a closure member.

[0003] According to the current technology, such an operating cylinder is manufactured, for example, by screwing a closure member and a cylinder tube together. Such an operating cylinder is also called a screw-type cylinder.

[0004] Furthermore, it is known from the current technology to connect a base closure member to a cylinder tube by MAG welding and then simply screw on a guide closure member.

[0005] Usually, the threads of the cylinder tube and the closure member are produced by a machining process.

[0006] Both screw-type cylinders and cylinders in which only one closure member is screwed and the other closure member is MAG welded are provided with high quality based on the current technology, and it has been found that they are products of the highest quality and high reliability.

[0007] The threads of the cylinder tube and the closure member are usually made by a shape cutting operation.

[0008] In terms of production, threads inevitably weaken the cylinder tube in the threaded area, so the tube wall thickness of the cylinder tube must be increased to remove material and insert the threads, which is disadvantageous. Therefore, the tube wall thickness must be considerably large enough to absorb the forces during operation, especially the forces caused by the operating pressure of the fluid. The drawbacks of this solution are increased material consumption and an increase in the final weight of the working cylinder. In manufacturing, when a desired specific angular position of the closure member relative to each other or to the cylinder tube is desired, it is even more difficult to align the threads of the closure member and the cylinder tube in such a manner that the appropriate tightening torque is applied during screwing.

[0009] WO2021 / 089069A1 describes a solution that overcomes many of the shortcomings of the prior art. This solution discloses an operating cylinder in which both closure members are joined to a cylinder tube by a laser-welded seam along the circumference. This solution presents production challenges in that, on the one hand, the laser-welded seam must have sufficient dimensions to absorb the forces between the cylinder tube and the associated closure members even at maximum operating pressure, and on the other hand, the energy input per unit length during welding must be sufficiently low so as not to impose excessive heat load on heat-sensitive components such as seals or guides. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] WO2021 / 089069A1 [Overview of the project] [Problems that the invention aims to solve]

[0011] The objective of this invention is to provide an operating cylinder that is highly reliable, can be manufactured in a cost-effective manner, and has a high load capacity. [Means for solving the problem]

[0012] This problem is solved by the configuration specified in claim 1. Preferred embodiments are obtained from the dependent claims.

[0013] The operating cylinder according to the present invention has a cylinder and a piston unit as its basic elements, and is particularly characterized by a special coupling section.

[0014] The cylinder of the operating cylinder according to the present invention comprises a cylinder tube, a closure member, and a further closure member.

[0015] As is known, the cylinder tube has a cylinder tube end and a further cylinder tube end, and therefore two cylinder tube ends opposite each other. A closure member is located at the cylinder tube end, and a further closure member is located at the further cylinder tube end. Hereafter, the cylinder tube end and the further cylinder tube end will be collectively referred to as the cylinder tube end, and the closure member and the further closure member will be collectively referred to as the closure member. The cylinder tube and the closure member located thereon form the interior of the cylinder.

[0016] The piston unit forms at least one working chamber inside the cylinder. Preferably, the piston unit is designed as an assembly of a piston and a piston rod, the piston rod slidingly passing through one of the closure members, in which case the closure member is a guide closure member. However, the piston unit may also be provided, for example, as a plunger piston, or as a piston unit of a cylinder having a continuous piston rod and thus having two equally sized effective surfaces for extension and retraction.

[0017] The operating cylinder according to the present invention also features a specially designed coupling section.

[0018] According to the present invention, the coupling section comprises a closure member, a cylinder tube end, and a ring weld seam provided thereon. The cylinder tube and the closure member are collectively referred to as the coupling partner.

[0019] In the area of ​​the connecting section, the closure member has a shaft portion, and the cylinder tube has a cylinder tube end portion. Both the shaft portion and the cylinder tube end portion form the connecting section.

[0020] The coupling section has a proximal and a distal section. The proximal and distal sections are directly adjacent to each other in the axial direction. In this context, the proximal direction and position indication is understood to specify the direction and position pointing toward the center of the operating cylinder, and the distal direction and position indication is understood to specify the opposite direction and position, i.e., the direction pointing toward the center of the operating cylinder.

[0021] According to the present invention, in the coupling section, the closure member's shaft portion is inserted axially into the cylinder tube end portion of the cylinder tube. As a result, the cylinder tube end portion surrounds the shaft portion like a sleeve.

[0022] According to the present invention, the shaft portion has a tapered design. Furthermore, the shaft portion has an overdimension relative to the inner diameter of the cylinder tube, at least partially (in sections). The overdimension correlates with the conicity. The overdimension is greatest in the area of ​​the thickened section of the cone and decreases in the direction of the tapered section of the cone. Also, the overdimension may not extend to the entire axial area, and in particular, there may be no conicity at all in the axial portion of the tapered section.

[0023] According to the present invention, the cylinder tube end is connected to the closure member in a positive-substance manner by a circumferential ring weld seam. The ring weld seam is designed as a laser ring weld seam. The laser ring weld seam also forms an airtight seal surface. The ring weld seam can be provided in the radial direction, the axial direction, or even inclined with respect to the main longitudinal axis. The circumferential ring weld seam forms a positive substance and airtight connection of the two joining partners against the pressure medium and preferably serves to absorb the peak load during operation.

[0024] According to a particularly preferred embodiment of the present invention, the taper of the shaft portion decreases in the distal direction. The fact that the taper decreases in the distal direction is understood here to mean that the outer diameter of the shaft portion, hereinafter referred to as the shaft outer diameter, decreases in a direction eccentric with respect to the axis. In this case, the shaft portion is inserted into the cylinder tube end portion with the portion having the larger outer diameter leading. The taper is preferably given in such a way that the shaft portion forms the lateral surface of a truncated cone, such that the outer diameter decreases linearly in the distal direction. However, the taper is also understood in the sense of the present invention to mean other shapes of the shaft portion in which the outer diameter becomes smaller from proximal to distal.

[0025] Furthermore, according to the present invention, the outer diameter of the shaft portion has a dimension that is larger compared to the inner diameter of the cylinder tube in the proximal region of the coupling section.

[0026] Therefore, the end of the shaft portion of the closure member facing towards the center of the working cylinder has an outer diameter with a dimension that is larger compared to the inner diameter of the cylinder tube. This larger dimension is reduced axially along the main longitudinal axis of the working cylinder.

[0027] Due to the interaction between the decreasing conicity in the distal direction and the large dimension with respect to the inner diameter of the cylinder tube, when the two coupling partners are joined, i.e., when the cylinder tube is guided onto the axial part of the closure member, an expansion of the cylinder tube along the circumference is caused. According to the present invention, the expansion occurs in the elastic region of the cylinder tube material. Thus, there is an elastic circumferential expansion in the proximal region according to the present invention. When viewed from the distal side, the circumferential expansion decreases corresponding to the decrease in conicity in this direction. Preferably, the circumferential expansion decreases as a result of the decrease in conicity in the distal direction to such an extent that the circumferential expansion decreases to zero in the distal region. The distal region and the proximal region are adjacent in the distal direction along the axis. Furthermore, it is also possible to reduce only the elastic circumferential expansion. In the context of this description, the boundary criterion between the proximal region and the distal region should be understood to be such that the maximum elastic circumferential expansion of the distal region is at most 50% of the maximum elastic circumferential expansion of the proximal region. In a particularly preferred embodiment, the minimum elastic circumferential expansion of the distal region is at most 20% of the maximum elastic circumferential expansion of the proximal region.

[0028] In the proximal region, since the tensile stress of the cylinder tube material increases along the circumference, the cylinder tube can easily follow the conical axial part and form a hybrid connection of form fit and press fit. Preferably, this hybrid connection itself provides a connection force sufficient to cope with the tensile force during the operation of the hydraulic cylinder between the two coupling partners.

[0029] The connection according to the present invention provides in particular the specific advantages described below.

[0030] Surprisingly, a solution has been found to impart a high load capacity to the connection between the cylinder tube and the associated closure member using means of a simple structure.

[0031] Advantageously, press fit, form fit, and active substance connection all act here to enable the absorption of particularly high tensile forces in the axial direction.

[0032] Furthermore, from a manufacturing perspective, it has the advantage of requiring virtually no additional effort compared to known solutions to achieve the conicity of the shaft portion of the closure component. At the same time, no additional machining of the cylinder tube is required.

[0033] Furthermore, a solution has been advantageously found in the present invention that allows the conicity to be designed such that the cylinder tube end portion exhibits little to no elastic circumferential expansion in the distal region, i.e., also in the area of ​​the laser ring weld seam. This means that there is little to no circumferential tensile stress. If high operating pressure generates axial tensile stress in the area of ​​the laser ring weld seam, multiaxial stress in the material at the end of the cylinder tube is thus avoided. This embodiment makes it possible to absorb greater axial tensile forces under conditions that are otherwise identical, particularly with respect to the thickness of the cylinder tube and the formation of the weld seam.

[0034] Furthermore, any dimensional tolerances of the inner diameter of the cylinder tube are compensated without requiring any additional measures.

[0035] At the same time, it is advantageous that the coupling according to the present invention is possible both between the cylinder tube and the bottom closure member and between the cylinder tube and the guide closure member.

[0036] According to an alternative embodiment of the present invention, the conicity of the shaft portion increases distally. Distal conicity increases are understood to mean that the outer diameter of the shaft increases eccentrically with respect to the axis. In this case, the shaft portion is inserted into the cylinder tube end portion with the portion having its tapered outer diameter leading.

[0037] According to this aspect of the present invention, there is a special advantage in that the centering of the closure member relative to the cylinder tube, and consequently the joining of the coupling partners, is facilitated, thus making assembly easier. In this design, any dimensional tolerance of the inner diameter of the cylinder tube is compensated without requiring any further additional measures.

[0038] According to an advantageous further development, the operating cylinder is characterized in that the closure member has an axial closure member ring surface, and the cylinder tube has an axial cylinder tube ring surface. The two ring surfaces also form a common ring contact surface. A ring welding seam is provided radially on the ring contact surface. The cylinder tube and the closure member are welded at the contact surface. Pressure resistance and airtightness are achieved by positive material connection.

[0039] Advantageously, when the cylinder tube ring surface and the axial closure member ring surface are joined, they form an axial stop, and as a result, the positional relationship between the joining partners is fixed in a secure manner in the axial direction, even before welding. In this way, it is also possible to apply compressive preload before or during welding.

[0040] According to another advantageous further development, the operating cylinder is characterized in that the cone of the shaft portion has a cone angle alpha, and the value of alpha is in the range of 0.1 to 1 degree with respect to the main longitudinal axis.

[0041] Angle alpha forms an undercut in the pull-out direction. This undercut is used for a shape-fit connection with the corresponding mating joint. This shape-fit connection ensures a permanent bond between the bonding partners. Due to the undercut, the bond force is lower than the pull-out force.

[0042] It was found that when the conicity angle alpha is in the range of 0.1 to 1 degree, it is possible to achieve both favorable elastic circumferential expansion of the cylinder tube end portion in the proximal region and little to no elastic circumferential expansion of the cylinder tube end portion in the distal region. This simultaneously enables high load-bearing pressure-fit and shape-fit connections and avoidance of multiaxial material stress in the ring weld seam area.

[0043] According to another advantageous further development, the operating cylinder is characterized in that the elastic circumferential expansion of the cylinder tube in the proximal region is in the range of 0.02% to 0.5%.

[0044] The circumferential expansion in this area is within the elastic range of the steel used and below the limit of its plastic range. Therefore, the resulting stress along the circumference causes a force to accumulate during joining, and this force supports the shape-fit connection with the angled closure member.

[0045] According to the following advantageous further development, the operating cylinder is characterized in that the closure member has a higher modulus of elasticity than the cylinder tube.

[0046] The combination of the angle alpha of the closure member and the inner diameter and circumferential expansion of the cylinder tube requires a specific material pairing. The closure member must have sufficient hardness in its conical axial portion to withstand the joining process, ensuring an undercut after the joining process. In contrast, the cylinder tube must expand sufficiently to conform smoothly to the undercut. The result is a shape-fit connection. Therefore, it is preferable that the two joining partners have different material hardness and elasticity.

[0047] In a further advantageous development, the operating cylinder is characterized in that the closure member has a chamfered portion at the inlet of the closure member, or the cylinder tube has a chamfered portion at the inlet of the cylinder tube.

[0048] To simplify the joining process, the closure member is provided with an outer chamfer so that the two joining partners are properly positioned relative to each other, and alternatively or additionally, the cylinder tube is provided with an inner chamfer. Furthermore, the sliding of the two chamfers relative to each other supports the expansion process of the cylinder tube.

[0049] In a further advantageous development, the operating cylinder is characterized in that the cylinder tube ring surface has an inclination angle beta, and the value of beta is in the range of 0.1 to 1 degree.

[0050] In this further development, the inclination angle β preferably coincides with the cone angle α. This further development is based on the fact that, in the cross-sectional view, as a result of elastic circumferential expansion in the proximal region, the cylinder tube is adjacent to the axial portion of the closure member at a cone angle α. In this case, the axial cylinder tube ring surface is also inclined at this angle. As a result, this surface forms a wedge-shaped gap that extends radially from the center with respect to the axial closure member ring surface, which is positioned perpendicular to the main longitudinal axis. In the further development presented here, the angle is corrected, and surface parallelism is created between the axial cylinder tube ring surface and the axial closure member ring surface, resulting in a highly rigid sealing laser ring weld seam.

[0051] The present invention will be further described in detail with reference to the following figures as examples. [Brief explanation of the drawing]

[0052] [Figure 1] This is a schematic cross-sectional view of an operating cylinder, where the angle of cone, which has decreasing cone in the distal direction, is exaggerated. [Figure 2] This is an enlarged cross-section of the joint section, with the conicity angle exaggerated. [Figure 3] These are cross-sectional and enlarged cross-sectional views of the operating cylinder. [Figure 4] This is a cross-sectional view and an enlarged cross-section of an operating cylinder in which the conicity increases distally. [Figure 5] This is a cross-sectional view of the operating cylinder showing further coupling sections. [Modes for carrying out the invention]

[0053] Here, the same reference number in various figures refers to the same feature or component. Reference numbers are also used in the description if they are not shown in the relevant figure.

[0054] Figure 1 shows a schematic cross-sectional view of one end of the operating cylinder 1.

[0055] The actuating cylinder 1 comprises a piston unit 2, a cylinder tube 3, and a closure member 4a. The cylinder tube 3 has two openings, one of which is closed by the closure member 4a and the other by a further closure member 4b. In a fully assembled actuating cylinder 1, the piston unit 2 slides through the further closure member 4b. In this exemplary embodiment, the piston unit 2 is designed in two parts, consisting of a piston rod and a piston. The piston unit 2 moves within the cylinder interior 6, where it forms the actuating chamber 6.1.

[0056] The closure member 4a is positioned at the end 5a of the cylinder tube.

[0057] To assemble the operating cylinder 1, the cylinder tube 3 is pressed onto the closure member 4a. In this process, the joining path is overcome by force. For this purpose, the closure member 4a and the cylinder tube 3 are brought into contact with the chamfered inlet portion 4a.3 of the closure member and the chamfered inlet portion 5a.3 of the cylinder tube. The chamfered portions are used to more precisely position the joining partners 4a and 3 relative to each other. During the axial joining operation, the cylinder tube end portion 5a.1 slides on the axial portion 4a.1 of the closure member 4a. In this sliding process, the cylinder tube end portion 5a.1 is elastically expanded and conforms smoothly around the axial portion 4a.1 of the closure member 4a, in which case the axial portion expands distally by a cone angle α, and as a result, this axial portion has a larger dimension in the proximal region 7a.1 compared to the inner diameter of the cylinder tube 3. The cylinder tube end portion 5a.1 is then extended in the proximal region 7a.1 of the connecting section 7a.

[0058] This extension provides a shape-fit connection between the coupling partners 4a and 3 that is also effective in the axial direction. The shape-fit connection interacts with a pressure-fit connection that also acts in the axial direction due to static friction between the inner lateral surface of the cylinder tube 3 in the region of the cylinder tube end portion 5a.1 and the conical outer lateral surface of the axial portion 4a.1 of the closure member 4a.

[0059] The two joining partners are joined with the assistance of force until the cylinder tube ring surface 5a.2 rests on the closure member ring surface 4a.2. The two ring surfaces 4a.2 and 5a.2 are the respective end faces of the joining partners, perpendicular to the main longitudinal axis 9 in the axial direction. The joining process is completed when the two ring surfaces 4a.2 and 5a.2 come into contact with each other.

[0060] The ring weld seam 8a is provided along the circumference of the cylinder tube 3, perpendicular to the main longitudinal axis 9, at the level of the ring surfaces 4a.2 and 5a.2, in order to seal the cylinder 1 in an active material and airtight manner.

[0061] Figure 2 shows an enlarged cross-section of Figure 1, where the conicity angle alpha is again shown in an exaggerated manner. In this exemplary embodiment, the conicity angle alpha is 0.2 degrees. Due to the conicity of the proximal portion 7a.1 of the connecting section 7a, the outer diameter of the shaft portion 4a.1 is larger than the inner diameter of the cylinder tube 3. As a result of this larger dimension, the cylinder tube 3 exhibits elastic circumferential expansion at the cylinder tube end portion 5a.1, which becomes smaller towards the distal direction. The geometry of the cone is designed so that there is no larger dimension compared to the inner diameter of the cylinder tube 3 in the distal region 7a.2 at the base of the shaft portion 4a.1, and therefore there is no elastic circumferential expansion of the cylinder tube 3 in the distal region of the connecting section 7a.

[0062] Furthermore, Figure 2 shows the inclination angle beta of the cylinder tube ring surface 5a.2 provided in an exemplary embodiment. In the exemplary embodiment, the inclination angle beta is 0.2 degrees, which is consistent with the value of the conicity angle alpha in this embodiment. The inclination angle beta compensates for the inclined position of the cylinder tube wall caused by the inequality of the elastic circumferential expansion decreasing distally over the axial portion 4a.1. As a result, the cylinder tube ring surface 5a.2 is precisely flat on the closure member ring surface 4a.2, and consequently, a ring weld seam 8a with high load-bearing capacity can be provided there as a laser ring weld seam extending throughout the entire depth of the weld seam. At the same time, the laser ring weld seam is not subjected to any tensile stress acting circumferentially on the material of the cylinder tube 3.

[0063] Figure 3 also shows a cross-sectional view in which the conical angle alpha is not exaggerated, and therefore the conical axial portion of the closure member 4a appears substantially cylindrical.

[0064] In the representation shown in Figure 3, the cylinder tube 3 and the closure member 4a are not yet connected, and therefore the shaft portion 4a1 is not yet inserted into the cylinder tube 3 at the cylinder tube end portion 5a1. Figure 3 specifically shows the arrangement and positional relationship between the closure member ring surface 4a.2 and the cylinder tube ring surface 5a.2, and between the closure member inlet chamfer portion 4a.3 and the cylinder tube inlet chamfer portion 5a.3.

[0065] Figure 4 shows an exemplary embodiment in which the conicity of the shaft portion 4a1 increases distally. Here, the tapered outer diameter is given to the proximal region 7a.1, and the increased outer diameter of the shaft is given to the distal region 7a.2. Thus, the conicity angle alpha expands in the opposite direction compared to the exemplary embodiments shown in Figures 1 and 2. When the cylinder tube 3 is cut strictly perpendicular to its length, the inclination angle beta opens outward due to the elastic expansion of the cylinder tube 3, and as a result, deep penetration of the laser steel into the butt joint between the closure member ring surface 4a.2 and the cylinder tube ring surface 5a.2 is supported during welding, making it possible to produce a ring weld seam 8a with particularly high load-bearing capacity.

[0066] Figure 5 shows an exemplary embodiment of an operating cylinder in which closure members 4a and 4b according to the present invention are coupled to both cylinder tube ends 5a and 5b. In addition to the coupling section 7a to the closure member 4a already shown in other figures at the cylinder tube end 5a, in this exemplary embodiment, a further closure member 4b, which is here designed as a guide closure member, is additionally coupled to the cylinder tube 3 at a further coupling section 7b at the further cylinder tube end 5b. The further coupling section 7b is designed similarly to coupling section 7a, and therefore the description relating to coupling section 7a also applies accordingly to the further coupling section 7b. [Explanation of symbols]

[0067] 1 cylinder 2 Piston Units 3 Cylinder Tube 4a Closure member 4a.1 Shaft section 4a.2 Ring surface of closure member 4a.3 Chamfered section at the entrance of the closure member 4b Further closure members 5a Cylinder tube end 5a.1 Cylinder tube end portion 5a.2 Cylinder, tube, and ring surface 5a.3 Cylinder tube inlet chamfer 5b Further cylinder tube ends 6 Cylinder interior 6.1 Working Chamber 7a Joined section 7a.1 Proximal area 7a.2 Distal segment 7b Further joining sections 8A Ring Weld Seam 9 Main longitudinal axis α Cone angle alpha β tilt angle beta

Claims

1. An operating unit having a cylinder (1) and a piston unit (2), The cylinder (1) comprises a cylinder tube (3), a closure member (4a), and a further closure member (4b). The cylinder tube (3) has a distal cylinder tube end (5a) in the axial direction of the cylinder tube (3) and a further proximal cylinder tube end (5b) opposite to the distal end, the closure member (4a) is provided on the cylinder tube end (5a), and the further closure member (4b) is provided on the further cylinder tube end (5b), The cylinder tube (3) and the closure members (4a, 4b) form the inside of the cylinder (6). The piston unit (2) has at least one working chamber (6.1) inside the cylinder (6), The closure member (4a) has a shaft portion (4a.1), the cylinder tube (3) has a cylinder tube end portion (5a.1), and the shaft portion (4a.1) and the cylinder tube end portion (5a.1) form a connecting section (7a). In the coupling section (7a), the closure member (4a) is inserted axially into the cylinder tube (3) at the cylinder tube end portion (5a.1) by the shaft portion (4a.1), and the coupling section has a proximal region (7a.1) on the proximal side and a distal region (7a.2) on the distal side. The shaft portion (4a.1) has a predetermined conicity, The shaft portion (4a.1) has a dimension that is at least partially larger than the inner diameter of the cylinder tube (3), and the cylinder tube (3) has elastic circumferential expansion therein. The coupling section (7a) is designed to connect the closure member (4a) and the cylinder tube (3) in the manner of axial pressure fitting and shape fitting. The cylinder tube end (5a) is connected to the closure member (4a) by a circumferential ring weld seam (8a), the ring weld seam (8a) is designed as a laser weld seam and forms a pressure medium sealing surface. The conicity is designed to decrease toward the distal side by the diameter of the shaft portion in the proximal region (7a.1), which is larger than the diameter of the shaft portion in the distal region (7a.2), and the shaft portion (4a.1) has a larger dimension than the inner diameter of the cylinder tube (3) in the proximal region (7a.1) of the coupling section (7a). An operating cylinder in which the cylinder tube (3) exhibits elastic circumferential expansion in the proximal region (7a.1).

2. The closure member (4a) has an axial closure member ring surface (4a.2), and the cylinder tube (3) has an axial cylinder tube ring surface (5a.2), and The operating cylinder according to claim 1, characterized in that both ring surfaces form a common contact ring surface, and the ring welding seam is provided radially on the contact ring surface.

3. The operating cylinder according to claim 1 or 2, characterized in that the conicity of the shaft portion (4a.1) has a conicity angle alpha, and alpha is in the range of 0.1 to 1 degree with respect to the main longitudinal axis 9.

4. The operating cylinder according to any one of claims 1 to 3, characterized in that the elastic circumferential expansion of the cylinder tube (3) in the proximal region (7a.1) is 0.02% to 0.5%.

5. The operating cylinder according to any one of claims 1 to 4, characterized in that the closure member (4a) has a higher modulus of elasticity than the cylinder tube (3).

6. The operating cylinder according to any one of claims 1 to 5, characterized in that the closure member has a chamfered portion (4a.3) at the inlet of the closure member, or the cylinder tube has a chamfered portion (5a.3) at the inlet of the cylinder tube.

7. The operating cylinder according to claim 2, characterized in that the cylinder tube ring surface (5a.2) has an inclination angle beta, and beta is in the range of 0.1 to 1 degree.

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