Working cylinder

Abstract

The invention relates to a working cylinder, comprising a cylinder (1) and a piston unit (2), wherein the cylinder (1) has a cylinder tube (3), a first closure part (4a) and a second closure part (4b), wherein the cylinder tube (3) has a first cylinder tube end (5a) and a second cylinder tube end (5b), wherein the first closure part (4a) is arranged on the first cylinder tube end (5a) and the second closure part (4b) is arranged on the second cylinder tube end (5b), and wherein the cylinder tube (3) and the closure parts (4a, 4b) form a cylinder interior (6), wherein the piston unit (2) forms at least one working space (6.1) in the cylinder interior (6), passes through the closure part (4a) in a sliding manner and has an outer end portion (2.1), characterized in that the working cylinder has a rod-side threaded coupling module (7) which is designed to be corrosion-resistant and which has a threaded portion (7.1) and a weld-on portion (7.2), in that the threaded portion (7.1) is designed for coupling to a device to be actuated, in that the rod-side threaded coupling module (7) is welded by its weld-on portion (7.2) to the outer end portion of the piston unit (2) by means of a weld seam (7.4), and in that the threaded portion is arranged in a longitudinal axis (7.3) of the piston unit (2).

Description

[0001] Working cylinder

[0002] The invention relates to a working cylinder with coupling sections for a screw coupling with a device to be actuated.

[0003] It is known from the prior art to screw and thus couple working cylinders to actuated devices using fastening threads. This can be done directly or indirectly via connection modules such as ball joints, fork eyes, and the like.

[0004] Such fastening threads are machined on both the piston rods and the base cap. A disadvantage of machining a fastening thread on a piston rod, for example, is that the previously applied valuable chrome plating is removed, thus destroying the corrosion protection. Another disadvantage is that wrench flats intended for applying torque or for counter-holding during screwing require significant material removal, resulting in an undesirable cross-sectional weakening.

[0005] A subsequent coating to provide corrosion protection is not possible or only possible with great effort.

[0006] The disadvantage is that the unprotected fastening threads are subject to high levels of corrosion and rust very quickly. A known countermeasure is to apply a thick layer of grease to reduce corrosive influences, especially during sea transport. This grease layer must be renewed after installation. In addition to the unsatisfactory corrosion protection effect, the environmental impact and the high manual labor required are also disadvantages.

[0007] Confirmation copy -

[0008] The object of the invention is to provide a thread-coupled working cylinder that is reliably protected against corrosion and can be manufactured with reduced material usage and time expenditure.

[0009] The problem is solved by the features listed in claim 1 and, according to a further aspect of the invention, by the features listed in claim 2. Preferred developments are set out in the subclaims.

[0010] The working cylinder according to the invention has a cylinder and a piston unit as basic elements and is characterized by a special threaded coupling module

[0011] The cylinder of the working cylinder according to the invention comprises, in a manner known per se, a cylinder tube, a first closure part and a second closure part.

[0012] The cylinder tube has two opposite cylinder tube ends. The two opposite cylinder tube ends are hereinafter referred to as the first cylinder tube end and the second cylinder tube end, and collectively as the cylinder tube ends.

[0013] The first closure part is arranged at the first cylinder tube end, and the second closure part is arranged at the second cylinder tube end. The first closure part and the second closure part are collectively referred to as the closure parts below. The cylinder tube and the closure parts arranged thereon form a cylinder interior. For this purpose, the two closure parts are designed such that they are pressure-tightly connected to the respective cylinder tube ends. For this purpose, the two closure parts are preferably laser-welded to the cylinder tube along the circumferential common contact surface.

[0014] The piston unit forms at least one working chamber in the cylinder interior. The piston unit is preferably designed as an assembly comprising a piston and piston rod, with the piston rod sliding through at least one of the closure parts, which then serves as a guide closure part. However, the piston unit can also be a plunger piston or a piston unit of a synchronous cylinder, for example. The working cylinder according to the invention can also be of other types, in particular a differential working cylinder or a pull cylinder. It is preferably a hydraulic cylinder, but is not limited thereto.

[0015] The piston unit has an outer end section. The outer end section is the distal head section of the piston unit, preferably the piston rod, located outside the cylinder interior. In the case of a plunger cylinder, this is the distal head of the plunger piston.

[0016] The working cylinder according to the invention is also characterized by a coupling section designed in a special way.

[0017] A coupling section within the meaning of the present invention is understood to be the part of the working cylinder that is connected to a device to be actuated, for example, an excavator arm, and via which the forces provided by the working cylinder are transmitted or the forces emanating from the device to be actuated are absorbed. The device to be actuated itself is not a component of the working cylinder according to the invention. It merely represents the functional context of the working cylinder according to the invention. Typically, two opposing coupling sections are arranged on the working cylinder, with at least one coupling section being designed according to the invention.

[0018] For this purpose, the working cylinder according to the invention has a rod-side threaded coupling module. According to the invention, the rod-side threaded coupling module is designed to be corrosion-resistant and is preferably a galvanized component or a stainless steel component, in particular a V2A or V4A component.

[0019] The threaded coupling module according to the invention comprises a threaded portion and a weld-on portion. Preferably, the rod-side threaded coupling module is designed in the shape of a screw, with the threaded shaft forming the threaded portion and the screw head forming the weld-on portion. The thread of the threaded portion is also referred to below as the fastening thread or coupling thread.

[0020] The threaded section is designed for coupling to the device to be actuated and is screwed into a receptacle as intended. Preferably, a metric thread is used.

[0021] The weld-on section adjoins the threaded section in a longitudinal direction and, according to the invention, is welded to the outer end section of the piston unit by means of a weld seam. The weld partner of the weld-on section is preferably the outer head section of a piston rod. However, the term "rod-side threaded coupling module" is also used in the context of the present invention when the outer end section does not refer to a piston rod in the narrower sense, but rather, for example, to a plunger piston of a plunger cylinder.

[0022] The weld seam is preferably formed as a circumferential laser weld seam. This advantageously creates a welded joint that connects the corrosion-resistant surface coating of the piston rod to the corrosion-resistant rod-side threaded coupling module, providing a continuously corrosion-resistant surface. According to the present invention, a double-threaded cylinder preferably has two rod-side threaded coupling modules, each of which is welded to the two outer end sections of the piston rod with a weld seam.

[0023] According to a further aspect of the invention, the working cylinder according to the further independent claim is characterized by a bottom-side threaded coupling module.

[0024] The basic design of the working cylinder with a bottom-side threaded coupling module corresponds to the basic design of the working cylinder with a rod-side threaded coupling module, so that the description contents relating to this apply accordingly, unless the following special features apply.

[0025] In the cylinder of the working cylinder with a bottom-mounted threaded coupling module, only the first locking part is designed as a guide locking part. The second locking part is a bottom locking part.

[0026] The characteristic feature here is the threaded coupling module on the bottom.

[0027] The base-side threaded coupling module is essentially designed in the same way as the rod-side threaded coupling module. Therefore, the descriptions for the rod-side threaded coupling module also apply to the base-side threaded coupling module, taking into account the special features.

[0028] The bottom-side threaded coupling module and the rod-side threaded coupling module are also referred to as the threaded coupling module and collectively as the threaded coupling modules. The bottom-side threaded coupling module is also corrosion-resistant and has a threaded section and a weld-on section. In the bottom-side threaded coupling module, the weld-on section is welded to an outer axial surface of the bottom closure part by means of a weld seam. The outer axial surface is the bottom-side, outward-facing cover surface of the bottom closure part. This is usually a circular surface of a cylindrical bottom closure part.

[0029] In addition, in the threaded coupling modules, the threaded section is arranged in the longitudinal axis of the working cylinder, wherein in particular in the rod-side threaded coupling module the threaded section is arranged in the longitudinal axis of the piston unit and in the bottom-side threaded coupling module the threaded section is arranged in the longitudinal axis of the cylinder.

[0030] A working cylinder can therefore have either one or two rod-side threaded coupling modules, one bottom-side threaded coupling module, or one rod-side and one bottom-side threaded coupling module.

[0031] The solution according to the invention has the following advantages in particular both in the design of the threaded coupling module as a rod-side threaded coupling module and as a base-side threaded coupling module.

[0032] Surprisingly, a very simple yet particularly effective solution was found to provide reliable corrosion protection for the fastening threads. Unlike the state of the art, this corrosion protection is achieved without additional measures and without harmful environmental influences.

[0033] The production of a working cylinder according to the invention is also particularly cost-effective and time-saving. Instead of the complex machining of a fastening thread, only laser welding is required, which typically takes a maximum of two seconds. Another advantage, particularly with a rod-side threaded coupling module, is the material savings made possible by the fact that the length of the cost-intensive piston rod can be reduced by the section no longer required for a fastening thread to be machined directly onto the piston rod. This length is advantageously replaced by the weldable threaded coupling module.

[0034] Another advantage is the high material quality and thus the high mechanical load capacity of the welded threaded coupling modules according to the invention, especially when they are designed as standardized screws.

[0035] According to an advantageous further development, the rod-side or the base-side threaded coupling module is designed as a cap screw.

[0036] The head of the cap screw forms the welding section and the threaded shaft of the cap screw forms the threaded section.

[0037] Advantageously, the head of the cap screw provides a weld-on section with a cross-sectional area larger than the cross-sectional area of ​​the threaded section. Furthermore, according to this refinement, the threaded coupling module can advantageously be provided by an inexpensive, readily available component. It is particularly advantageous that a high degree of standardization and quality assurance, expressed, for example, by strength classes, exists and can be utilized. These screws are preferably of strength class 8.8, which are also highly suitable for laser-welded welds.

[0038] According to a further advantageous development, the rod-side threaded coupling module is designed as a hexagon screw. In addition to the aforementioned advantages of a cap screw, there is the particular advantage that the hexagon head remains laterally accessible as a screw drive after the connection to the outer end section of the piston unit has been established by means of the weld seam. This advantageously provides a key flat as a drive for screwing the rod-side threaded coupling module to the device to be actuated, without any additional measures.

[0039] According to another advantageous development, the working cylinder according to the invention is characterized in that the bottom-side threaded coupling module is designed as a cylinder head screw and the welding section as a cylindrical screw head, that the second closure part, which is present as a bottom closure part, has a cylindrical bore on an outer axial surface, that the cylindrical screw head is received radially in a form-fitting manner by the cylindrical bore and that the weld seam is designed as an axial ring weld seam

[0040] According to this advantageous development, a bore can be created as a blind hole in the outer axial surface during production of the base closure part by machining. The inner diameter of this bore is matched to the outer diameter of the cylindrical screw head so that an exact fit or interference fit is preferably achieved. The base-side threaded coupling module, designed here as a cylinder head screw, is then inserted axially into the bore with the screw head and is fixed there axially in the distal direction with the exception of the linear degree of freedom. An axially directed laser ring weld seam is then created, preferably by laser welding, to create a material bond between the threaded coupling module and the base closure part.

[0041] This further development simplifies production in a particularly advantageous way, since the threaded coupling module and the base closure part can be precisely aligned to one another before welding and fixed by means of a press fit.

[0042] According to a further development, the working cylinder is characterized in that the rod-side threaded coupling module or the base-side threaded coupling module is designed as a galvanized screw or as a stainless steel screw.

[0043] Galvanized and stainless steel screws offer high corrosion resistance and are available cost-effectively in high, process-reliable quality. Stainless steel screws are defined as screws made of stainless steel, for example, with material number 4301. This provides a consistently corrosion-resistant surface, particularly when the weld seam is created using a laser weld.

[0044] According to another advantageous development, the threaded coupling module has a cover protective layer.

[0045] In addition to the use of corrosion-resistant screws or threaded studs as weld-on connectors, this refinement also provides for the laser welding of other threaded coupling modules coated with protective coatings to the base closure part or piston unit. Such a protective coating can be a chromium or nickel layer, for example.

[0046] The invention is illustrated by way of example with reference to

[0047] Fig. 1 Working cylinder with threaded coupling modules as head screws (sectional view

[0048] Fig. 2 Working cylinder with threaded coupling modules as stud bolts (sectional view) explained in more detail.

[0049] Identical reference symbols in the various figures refer to identical features or components. These reference symbols are used in the description even if they are not shown in the respective figure.

[0050] Fig. 1 shows a working cylinder in an embodiment in which the threaded coupling modules 7, 8 are designed as head screws.

[0051] The basic structure of the working cylinder consists of the cylinder 1 and the piston unit 2.

[0052] The cylinder 1 has a cylinder tube 3 with a first cylinder end 5a and a second cylinder tube end 5b. The first closure part 4a, here as a guide closure part, is arranged at the first cylinder tube end 5a, and the second closure part 4b, here as a base closure part, is arranged at the second cylinder tube end, each sealingly and by means of a laser weld seam, so that the closure parts 4a, 4b and the cylinder tube 3 enclose a cylinder interior 6.

[0053] In the exemplary embodiment, the piston unit 2 is formed in two parts, consisting of a piston and a piston rod (each without a reference symbol) that are connected to one another. The piston unit 2, together with the piston rod, penetrates the first closure part 4a and simultaneously forms at least one working chamber 6.1 in the cylinder interior 6. Reference numeral 6.1 denotes the piston chamber in the exemplary embodiment. The piston rod chamber (without a reference symbol) provides a further working chamber in the exemplary embodiment.

[0054] The rod-side threaded coupling module 7 is arranged on the outer end section 2.1 of the piston unit 2, here the end face of the piston rod. It is designed as a hexagon screw, so that the threaded section 7.1 of the threaded coupling module 7 is formed by the screw shaft and the weld-on section 7.2 of the threaded coupling module 7 is formed by the hexagon head. The weld-on section 7.2 thus has an axial end face that is opposite the axial end face of the outer end section 2.1. Both end faces are welded over their entire surface by the weld seam 7.4 as a laser weld, with the weld seam 7.4 being arranged radially. The radial arrangement is highlighted by the dashed line. After welding, the wrench flats of the hexagon head are advantageously available for assembly by screwing the threaded section 7.1 to a device to be actuated.For optimal power transmission, the longitudinal axis of the threaded section 7.1 lies on the longitudinal axis 7.3 of the piston unit 2.

[0055] Furthermore, the bottom-side threaded coupling module 8, which is designed as a cylinder head screw, is arranged on the outer axial surface 4b.1 of the second closure part 4b. The second closure part 4b has a bore on the outer axial surface 4b.1, the inner diameter of which corresponds to the outer diameter of the cylindrical head of the cylinder head screw and which snugly accommodates the head of the cylinder head screw. Thus, the head of the cylinder head screw forms the weld section 8.2, and its threaded shank forms the threaded section 8.1. Here, too, the weld is designed as laser welding, with the weld seam 8.4 being introduced axially, as highlighted by the dashed line. The weld seam 8.4 thus forms a cylindrical surface at the contact surface between the bore and the weld section 8.2, formed by the screw head. Here, too, the longitudinal axis of the threaded section 8 is located for optimal force transmission.1 on the longitudinal axis 8.3 of cylinder 1.

[0056] Fig. 2 shows a further embodiment, which corresponds in basic structure to the embodiment according to Fig. 1. According to Fig. 2, however, the threaded coupling modules 7, 8 are designed as stud bolts, which have a conical end, which forms the welding section 7.2, 8.2.

[0057] The piston unit 2 has a depression on its outer end section 2.1, as does the second closure part 4b on its outer axial surface 4b.1, the angle of inclination of which corresponds to the angle of inclination of the conical end of the stud screws.

[0058] The weld seam 7.4, 8.4 is arranged on the corresponding conical surfaces, the angle of inclination of which is highlighted by the respective dashed line.

[0059] Reference symbols used

[0060] 1 cylinder

[0061] 2 piston unit

[0062] 2.1 outer end section

[0063] 3 cylinder barrel

[0064] 4a first closure part

[0065] 4b second closure part

[0066] 4b.1 outer axial surface

[0067] 5a first cylinder ear end

[0068] 5b second cylinder tube end

[0069] 6 cylinder interior

[0070] 6.1 Workspace

[0071] 7 rod-side threaded coupling module

[0072] 7.1 Threaded section of the rod-side threaded coupling module

[0073] 7.2 Weld-on section of the rod-side threaded coupling module

[0074] 7.3 Longitudinal axis of the piston unit

[0075] 7.4 Weld seam of the rod-side threaded coupling module

[0076] 8 bottom-side threaded coupling module

[0077] 8.1 Threaded section of the bottom threaded coupling module

[0078] 8.2 Weld-on section of the bottom threaded coupling module

[0079] 8.3 Longitudinal axis of the cylinder

[0080] 8.4 Weld seam of the bottom threaded coupling module

Claims

Patent claims 1. Working cylinder comprising a cylinder (1) and a piston assembly (2), wherein the cylinder (1) has a cylinder tube (3), a first closure part (4a) and a second closure part (4b), wherein the cylinder tube (3) has a first cylinder tube end (5a) and a second cylinder tube end (5b), wherein the first closure part (4a) is arranged at the first cylinder tube end (5a) and the second closure part (4b) is arranged at the second cylinder tube end (5b), and wherein the cylinder tube (3) and the closure parts (4a, 4b) form a cylinder interior (6), wherein the piston assembly (2) forms at least one working chamber (6.1) in the cylinder interior (6), slidably passes through the closure part (4a) and has an outer end section (2.1), characterized in that the working cylinder has a rod-side threaded coupling module (7) which is corrosion-resistant and has a threaded section (7.1) and a weld-on section. (7.2) features that the threaded section (7.1) is designed for coupling with a device to be actuated, that the rod-side threaded coupling module (7) with its welded section (7.2) is welded to the outer end section of the piston unit (2) by means of a weld seam (7.4), and that the threaded section is arranged in a longitudinal axis (7.3) of the piston unit (2).

2. Working cylinder comprising a cylinder (1) and a piston assembly (2), wherein the cylinder (1) comprises a cylinder tube (3), a first closure part (4a) and a second closure part (4b), wherein the cylinder tube (3) comprises a first cylinder tube end (5a) and a second cylinder tube end (5b), wherein the first closure part (4a) is arranged at the first cylinder tube end (5a) and is designed as a guide closure part, and wherein the second closure part (4b) is arranged at the second cylinder tube end (5b) and is designed as a bottom closure part, and wherein the cylinder tube (3) and the closure parts (4a, 4b) form a cylinder interior (6), wherein the piston unit (2) forms at least one working chamber (6.1) in the cylinder interior (6), slidably passes through the first closure part (4a) and has an outer end section (2.1), characterized in that the working cylinder has a bottom-side threaded coupling module (8) which is corrosion-resistant and has a threaded section (8.1) and a weld-on section (8.2) has that the threaded section (8.1) is designed for coupling with a device to be actuated, that the bottom-side threaded coupling module (8) with its welded section (8.2) is welded to an outer axial surface (4b.1) of the second closure part (4b) by means of a weld seam (8.4), and that the threaded section is arranged in a longitudinal axis (8.3) of the cylinder (1). Working cylinder according to one of the preceding claims 1 or 2, characterized in that the rod-side threaded coupling module (7) or the bottom-side threaded coupling module (8) is designed as a cap screw.

4. Working cylinder according to claim 3, characterized in that the rod-side threaded coupling module (7) is designed as a hexagon screw.

5. Working cylinder according to claim 3, characterized in that the bottom-side threaded coupling module (8) is designed as a cylinder head screw and the weld-on section (8.2) as a cylindrical screw head, that the second closure part (4b) has a cylindrical bore on an outer axial surface (4b.1), that the cylindrical screw head is radially positively engaged by the cylindrical bore, and that the weld seam is designed as an axial ring weld seam.

6. Working cylinder according to one of the preceding claims, characterized in that the rod-side threaded coupling module (7) or the bottom-side threaded coupling module (8) is designed as a galvanized screw or as a stainless steel screw.

7. Working cylinder according to one of the preceding claims, characterized in that the rod-side threaded coupling module (7) or the bottom-side threaded coupling module (8) has a protective cover layer. INCLUDES TWO PAGES OF DRAWINGS

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