WORKING CYLINDER AND METHOD FOR THE PRODUCTION THEREOF

Abstract

A working cylinder has a cylinder tube, a first closure part, a second closure part and a piston unit. The first closure part is arranged on a first cylinder tube end, the second closure part is arranged on a second cylinder tube end to define a cylinder interior. The piston unit defines at least one working chamber in the cylinder interior. The piston unit slides through the first closure part. The first closure part is joined to the cylinder tube by a first peripheral laser ring weld seam and the second closure part is joined to the cylinder tube by a second peripheral laser ring weld seam. The laser ring weld seams each define a fluid-tight sealing plane. A method for producing the working cylinder is provided.

Claims

1-18. (canceled)

19. A working cylinder, comprising: a cylinder tube, a first closure part, a second closure part and a piston unit; said cylinder tube having a first cylinder tube end and a second cylinder tube end; said first closure part being arranged at said first cylinder tube end and said second closure part being arranged at said second cylinder tube end, said cylinder tube and said first and second closure parts define a cylinder interior; said piston unit defining at least one working chamber in said cylinder interior, said piston unit slidably passing through said first closure part; said first closure part being joined to said cylinder tube in a material-locking manner by a first circumferential laser ring weld seam, said second closure part being joined to said cylinder tube in a material-locking manner by a second circumferential laser ring weld seam, and each of said laser ring weld seams defining a fluid-tight sealing plane;

20. The working cylinder according to claim 19, wherein said working cylinder is double-acting and is constructed as a differential working cylinder, said first closure part is constructed as a guide closure part and said second closure part is constructed as a bottom closure part, said first cylinder tube end is a guide-side cylinder tube end and said second cylinder tube end is a bottom-side cylinder tube end; said piston unit includes a piston and a piston rod, said piston is arranged in said cylinder interior and separates said cylinder interior into a piston crown working chamber and a piston rod working chamber and said piston rod slidably passes through said guide closure part.

21. The working cylinder according to claim 19, wherein said working cylinder is double-acting and is constructed as a synchronized cylinder, said first closure part is constructed as a first guide closure part and said second closure part is constructed as a second guide closure part, said piston unit includes a piston and a piston rod, said piston is arranged in said cylinder interior and separates said cylinder interior into a first piston rod working chamber and a second piston rod working chamber, and said piston rod slidably passes through said guide closure part and said second guide closure part.

22. The working cylinder according to claim 19, wherein said working cylinder is single-acting and is constructed as a plunger cylinder, said first closure part is constructed as a guide closure part and said second closure part is constructed as a bottom closure part, said first cylinder tube end is a guide-side cylinder tube end and said second cylinder tube end is a bottom-side cylinder tube end, said piston unit is a plunger piston with a plunger, said plunger is arranged in said cylinder interior and defines a working chamber in said cylinder interior, and said plunger slidably passes through said guide closure part.

23. The working cylinder according to claim 19, wherein a first circumferential sealing ring is arranged at an axial distance from said first laser ring weld seam in said cylinder interior between said first closure part and a cylinder tube inner wall of said cylinder tube at said first cylinder tube end, said sealing ring defines a first pressure-separated annular section between said first circumferential sealing ring and said first laser ring weld seam, and/or a second circumferential sealing ring is arranged at an axial distance from said second laser ring weld seam in said cylinder interior between said second closure part and said cylinder tube inner wall at said second cylinder tube end, and said second circumferential sealing ring defines a second pressure-separated annular section arranged between said second circumferential sealing ring and said second laser ring weld seam.

24. The working cylinder according to claim 19, wherein each of said laser ring weld seams has a ring weld seam depth, said ring weld seam depth has a ratio of 1.1 to 2.5 relative to a cylinder tube wall thickness.

25. The working cylinder according to claim 19, wherein each of said laser ring weld seams has a ring weld seam center axis, said ring weld seam center axis and a main longitudinal axis of said cylinder tube include a ring weld seam inclination angle of 20 to 70 degrees.

26. The working cylinder according to claim 19, wherein at least one closure part has an axial opening that is a circumferential concave receiving contour in which said cylinder tube engages, said receiving contour radially overlaps said cylinder tube, and a ring weld seam inclination angle thereof is 110 to 160 degrees.

27. The working cylinder according to claim 19, wherein at least one of the laser ring weld seams is arranged axially at a front face side of said cylinder tube and the ring weld seam is parallel to a longitudinal axis of said cylinder tube.

28. A method of producing a working cylinder, according to claim 19, comprising: a) joining the cylinder tube, the first closure part, the second closure part and the piston unit to a pre-assembly group; b) establishing a fixed relative positional relationship between the cylinder tube, the first closure part and the second closure part; c) performing laser welding of the cylinder tube to the first closure part by producing the first laser ring weld seam and to the second closure part by producing the second laser ring weld seam.

29. The method for producing a working cylinder according to claim 28, wherein in joining process step a) the first closure part is provided as a guide closure part, the second closure part is provided as a bottom closure part and the piston unit is defined by a piston and a piston rod that slidably passes through the first closure part, to define a pre-assembly group of a differential working cylinder.

30. Method for producing a working cylinder according to claim 28, wherein for the joining process step a) the first closure part is constructed as a guide closure part, the second closure part is constructed as a further guide closure part and the piston unit is defined by a piston and a piston rod that slidably passes through both closure parts to define a preassembly of a synchronous cylinder.

31. Method for producing a working cylinder according to claim 28, wherein for the joining process step a) the first closure part is provided as a guide closure part, the second closure part is provided as a bottom closure part and the piston unit is provided as a plunger piston to define a pre-assembly group of a plunger cylinder.

32. The method for producing a working cylinder according to claim 28, wherein in the laser welding process step c) the laser ring weld seams have a ring weld seam inclination angle of 20 to 70 degrees.

33. The method for producing a working cylinder, according to claim 28, wherein in the laser welding process step c) is carried out with a ring weld seam inclination angle of 110 to 160 degrees.

34. The method for producing a working cylinder, according to claim 33, wherein in step c) is carried out axially on the front face side.

35. The method for producing a working cylinder according to claim 28, wherein: in step a) joining is carried out by joining further a piston-rod-side fastening module to the pre-assembly group; in step b) the fixed relative positional relationship of the rod-side fastening module is established; and in step c), welding of a piston rod to the piston-rod-side fastening module is performed by producing a first fastening-module weld seam.

36. The method for producing a working cylinder according to claim 28, wherein: in step a) joining is carried out by joining further a bottom-side fastening module to the pre-assembly group; in step b) the fixed relative positional relationship of the bottom-side fastening module is established; and in step c) the welding of the second closure part to the bottom-side fastening module is performed by producing a second fastening module weld seam.

Description

[0134] FIG. 1 Differential working cylinder (overview)

[0135] FIG. 2 Enlarged detail at the guide-side cylinder tube end

[0136] FIG. 3 Enlarged detail at the bottom-side cylinder tube end

[0137] FIG. 4 Enlarged view of a laser weld seam to show the cross-section and the ring weld seam angle beta

[0138] FIG. 5 plunger cylinder with 90-degree weld seam and upstream O-ring

[0139] FIG. 6 Enlarged detail to FIG. 5 to show the O-ring and the annular section

[0140] FIG. 7 Synchronized cylinder with negative-obliquely inclined weld seam

[0141] FIG. 8 Enlarged detail to FIG. 7 to show the concave receiving contour

[0142] FIG. 9 Enlarged detail to FIG. 7 in exploded view

[0143] FIG. 10 Telescopic cylinder with combination of 90-degree weld seam and oblique seam

[0144] FIG. 11 Schematic representation of a bottom closure part with 0-degree weld seam.

[0145] FIG. 1 shows an overview of an embodiment of the working cylinder 1 designed as a differential working cylinder. The differential working cylinder 1 comprises the cylinder tube 2, the first closure part 3, here designed as a guide closure part, the second closure part 4, here designed as a bottom closure part, and the piston unit 5. The piston unit consists of the piston 5a and the piston rod 5b.

[0146] In this embodiment, the piston-rod-side fastening module 15 is arranged at the piston rod 5b and the bottom-side fastening module 17 is arranged on the second closure part 4 designed as a bottom closure part. Fastening bolts 15a, 17a, which are not elements of the invention and are shown merely for the sake of clarity, are assigned to each of the two fastening modules 15, 17.

[0147] The piston unit 5 is arranged in relation to the piston 5a and with sections of the piston rod 5b in the cylinder interior 8, and the piston rod 5b slidably passes through the first closure part 3 designed as a guide closure part.

[0148] The first closure part 3, designed as a guide closure part, closes the cylinder tube 2 at the first cylinder tube end 6, here the guide-side cylinder tube end, and the second closure part 4, designed as a bottom closure part, closes the second cylinder tube end 7, here the bottom-side cylinder tube end.

[0149] The two cylinder tube ends 6, 7 are bevelled and, consequently, have a larger contact surface with the two closure parts 3, 4. In this embodiment, the two closure parts 3, 4 are designed such that they project with a cylindrical section partially and precisely fitting into the cylinder tube and can thus be joined more easily to the pre-assembly group.

[0150] The main longitudinal axis 14 of the cylinder tube 2 runs centrally and longitudinally through the working cylinder 1.

[0151] FIG. 2 shows an enlarged detail of the area of the first cylinder tube end 6. This is the cylinder tube end on the guide side. Here, the geometric conditions of the first circumferential laser ring weld seam 9 are shown in particular. During welding, the first circumferential laser ring weld seam 9 is produced by a laser along the ring weld seam center axis 13 in this embodiment. This seam runs along the contact surface between the first cylinder tube end 6 and the first closure part 3. For this purpose, the previously assembled and temporarily fixed pre-assembly group consisting of the cylinder tube 2, the first closure part 3, the second closure part 4, the piston unit 5 and the two fastening modules 15, 17 is rotated around the main longitudinal axis of the cylinder tube 14 and in front of the laser.

[0152] The ring weld seam center axis 13 runs centrally through the first circumferential laser ring weld seam 9 and includes the ring weld seam inclination angle alpha in its extension with the main longitudinal axis of the cylinder tube 14. The ring weld seam depth 11 is the length of the ring weld seam center axis 13 which runs in the actual laser ring weld seam 9. Due to the angulation, the ring weld seam depth 11 is greater than the cylinder tube wall thickness 12. The ring weld seam depth corresponds to the hypotenuse of a right-angled triangle formed by the ring weld seam, the cylinder tube wall thickness 12 and a perpendicular.

[0153] This representation also shows the first fastening module weld seam 16 between the piston-rod-side fastening module 15 and the piston rod 5b. It is produced by means of the same laser welding method that is applied for the first circumferential laser ring weld seam 9.

[0154] Furthermore, the sliding bearing of the piston rod 5b in the first closure part 3 designed as a guide closure part is also shown with guide 20 and seal 19.

[0155] FIG. 3 shows an enlarged view of a section of the bottom end of the cylinder tube, which is the second end of the cylinder tube 7.

[0156] The structure of the illustration mainly corresponds to FIG. 2. The connection of the second closure part 4, designed as a bottom closure part, to the second cylinder tube end 7 is established analogously to the connection of the first closure part 3, designed as a guide closure part, to the first cylinder tube end 6 (see FIG. 2) by means of a laser welding process. Here, the second laser ring weld seam 10 is formed.

[0157] In addition to FIG. 2, this illustration shows the piston 5a separating the cylinder interior 8 into a piston crown working chamber 8a and a piston rod working chamber 8b. Both working chambers 8a, 8b are separately supplied with a hydraulic pressure medium via the fluid connections, and the working cylinder 1 designed as a differential cylinder is operated in this way.

[0158] Analogous to the piston-rod-side fastening module 15 (see FIG. 2), the bottom-side fastening module 17 is also fastened by means of a laser weld seam, the second fastening module weld seam 18.

[0159] FIG. 4 shows an enlarged laser weld seam. The first laser weld seam 9, between the first cylinder tube end 2 and the first closure part 3, shown here is an exemplary laser weld seam according to the present invention.

[0160] This first laser weld seam 9 has a ring weld seam depth 11 and a ring weld seam center axis 13. In this embodiment, the ring weld seam depth 11 is greater than the cylinder tube wall thickness 12.

[0161] The laser weld seam has a slight conicity. If two tangents are put at the edge contour of the laser weld seam, they intersect and form a ring weld seam angle beta. The ring weld seam center axis 13 is also the bisecting line of the ring weld seam angle beta and, together with the main longitudinal axis 14, includes the ring weld seam inclination angle alpha. Furthermore, the ring weld seam center axis 13 runs along the contact surface of the first cylinder tube end 6 and the first closure part 3. In this embodiment, the ring weld seam inclination angle alpha is 90 degrees.

[0162] FIG. 5 shows an embodiment of a working cylinder which is designed as a plunger working cylinder. Here, the piston unit 5, which is designed as a plunger piston, is guided in the cylinder tube 2. In addition, the piston unit 5 is guided in the first closure part 3, which is designed as a guide closure part. For this purpose, the plunger cylinder is equipped with the guides 20. The guide closure part is connected to the cylinder tube 2 at its first cylinder tube end 6 by means of the first laser ring weld seam 9. Opposite the guide closure part, the second closure part 4, here designed as a bottom closure part, is connected to the cylinder tube 2 at the second cylinder tube end 7 by the second laser ring weld seam 10. In this embodiment, the two laser ring weld seams 9, 10 have a ring weld seam inclination angle of 90 degrees.

[0163] The reference numerals and descriptive contents given in FIG. 1 for a differential working cylinder apply in addition.

[0164] The plunger working cylinder in the embodiment according to FIG. 5 also comprises an additional first circumferential sealing ring 21 at the first closure part 3. This additional sealing ring 21 is also referred to as an O-ring and is arranged radially between the cylinder tube 2 and the first closure part 3 and provides a pressure-tight seal which separates the second circumferential laser ring weld seam 10 from the pressure medium in a pressure-tight manner.

[0165] In FIG. 6 the area of the sealing ring 21 (O-ring) at the first closure part 3 from FIG. 5 is shown in an enlarged view. The sealing ring 21 (O-ring) is shown here in more detail and is located in spatial proximity to the first circumferential laser ring weld seam 9. In this embodiment, the sealing ring 21 (O-ring) is made of an elastic polymer. The heat input during laser welding remains sufficiently low to avoid damaging of the sealing ring 21 (O-ring) despite its close proximity to the first laser ring weld seam 9. From an axial point of view, there is a pressure-separated annular section 22 between the sealing ring 21 (O-ring) and the first laser ring weld seam 9. In this pressure-separated annular section 22, the operating pressure of the pressure medium is not applied to the inside of the cylinder tube so that forces from the pressure medium do not act radially on the cylinder tube 2 in this area. Thus, the cylinder tube 2 is not subject to buckling forces in this area and the first laser ring weld seam 9 is relieved.

[0166] In this design, the ring weld seam center axis 13 runs perpendicular to the main longitudinal axis 14 of the working cylinder 1.

[0167] FIG. 7 shows a synchronized working cylinder with a negative-obliquely inclined weld seam. In the synchronized working cylinder, both closure parts 3, 4 are designed as guide closure parts. The piston 5a is arranged in the axially central area of the piston rod 5b, which is guided by both closure parts 3, 4.

[0168] In this embodiment, the two cylinder tube ends 6, 7 each are inserted into a concave receiving contour 23 in the two closure parts 3, 4 and welded there by means of the laser welding process. The laser ring weld seam 9, 10 is negative-obliquely inclined here, which means an opposite bevelling of the contact surfaces (in comparison to, for example, the embodiment of FIG. 1) of the closure part 3, 4 and the cylinder tube end 6, 7.

[0169] In FIG. 8, the embodiment of FIG. 7 is shown in more detail in an enlarged view.

[0170] Here, the second cylinder tube end 7 is already inserted into the wedge-shaped concave receiving contour 23 and welded to the second closure part 4 by means of the second circumferential laser ring weld seam 10.

[0171] The ring weld seam center axis 13 and the main longitudinal axis 14 include the ring weld seam inclination angle alpha.

[0172] Here, the ring weld seam angle alpha has an angle greater than 90 degrees, in the embodiment of about 120 degrees.

[0173] FIG. 9 shows a schematic exploded view of the coupling partners according to FIG. 8. FIG. 9 shows the first cylinder tube end 6 and the first closure part 3 with the wedge-shaped concave receiving contour 23 before joining. The concave receiving contour 23 is designed to receive the first cylinder tube end 6 and to form a common contact surface with it, on which the first laser ring weld seam 9 is then arranged. FIG. 9 shows that the concave receiving contour 23 opens axially in the direction of the cylinder tube 2. Radial buckling forces acting on the cylinder tube 2 from the inside are thus absorbed in a positive-locking manner by a radial overlap 24. This is the inclined section of the concave receiving contour 23.

[0174] FIG. 10 shows an embodiment of a telescopic working cylinder. Compared to the previously described cylinder types, the telescopic working cylinder has a further cylinder tube 2a, which is arranged in the cylinder tube 2, as well as a further closure part 3a. The first closure part 3 and the further closure part 3a are designed as guide closure parts. The further cylinder tube 2a is welded to the further closure part 3a via a further circumferential laser ring weld seam 9a.

[0175] In this embodiment, straight laser ring weld seams (ring weld inclination angle alpha=90 degrees) are also combined with oblique laser ring weld seams (ring weld angle alpha <90 degrees).

[0176] In this embodiment, the first circumferential laser ring weld seam 9 on the first closure part 3 and the further circumferential laser ring weld seam 9a on the further closure part 3a are designed as oblique laser weld seams, and the second circumferential laser ring weld seam 10 on the second closure part 10 is designed as a straight laser weld seam.

[0177] FIG. 11 is a schematic representation of a detail of an embodiment in which the second circumferential laser ring weld seam 10 runs parallel to the main longitudinal axis.

[0178] Here, the second closure part 4, designed as a bottom closure part, is radially enclosed by the second cylinder tube 2. In the embodiment, the second closure part 4 and the annular surface of the cylinder tube 2 form a common front face side. However, it is also possible that one of the coupling partners axially protrudes or is set back relative to the other coupling partner.

[0179] The ring weld seam center axis 13 does not intersect the main longitudinal axis 14. The ring weld seam inclination angle alpha is 0 degrees.

LIST OF REFERENCE NUMERALS

[0180] 1 working cylinder [0181] 2 cylinder tube [0182] 2a further cylinder tube [0183] 3 first closure part [0184] 3a further closure part [0185] 4 second closure part [0186] 5 piston unit [0187] 5a piston [0188] 5b piston rod [0189] 6 first cylinder tube end [0190] 7 second cylinder tube end [0191] 8 cylinder interior [0192] 8a piston crown working chamber [0193] 8b piston rod working chamber [0194] 9 first circumferential laser weld seam [0195] 10 second circumferential laser weld seam [0196] 11 ring weld seam depth [0197] 12 cylinder tube wall thickness [0198] 13 ring weld seam center axis [0199] 14 main longitudinal axis [0200] 15 piston-rod-side fastening module [0201] 15a fastening bolts of the piston-rod-side fastening module [0202] 16 first fastening module weld seam [0203] 17 bottom-side fastening module [0204] 17a fastening bolts of the des bottom-side fastening module [0205] 18 second fastening module weld seam [0206] 19 seal [0207] 20 guide [0208] 21 circumferential sealing ring [0209] 22 pressure-separated annular section [0210] 23 concave receiving contour [0211] 24 radial overlap [0212] α ring weld seam inclination angle alpha [0213] β ring weld seam angle beta