Hollow piston cylinder

Abstract

The invention relates to a hollow piston cylinder (1) for clamping a component (for example a tool or a workpiece), comprising a clamping cylinder (4), a hollow piston (5) which is movable in the clamping cylinder (4), and a connecting rod (2) which is anchored in the axial bore in the hollow piston (5) so that the hollow piston (5), when axially moved by the pressure medium, carries along the connecting rod (2) in the axial direction. According to the invention, the connecting rod (2) can be anchored in the axial bore in the hollow piston (5) in various axial positions.

Description

[0001] DESCRIPTION

[0002] Hollow piston cylinder

[0003] Technical field of the invention

[0004] The invention relates to a hollow piston cylinder for clamping a component, in particular a tool or a workpiece.

[0005] Background of the invention

[0006] Hollow piston cylinders are known from the state of the art and are ideal for clamping workpieces that have a through bore or opening.

[0007] Figure 1 shows an example of such a conventional hollow piston cylinder 1, as is known from the prior art. The known hollow piston cylinder 1 comprises a drawbar 2, which is axially displaceable in the direction of the double arrow and has a T-slot head 3 at its free end for engaging a T-slot in the component to be clamped.

[0008] In addition, the hollow piston cylinder 1 has a clamping cylinder 4 in which a hollow piston 5 is displaceable in the axial direction.

[0009] To seal the hollow piston 5 in the clamping cylinder 4, a plurality of seals 6, 7, 8 are provided, wherein the seal 6 is arranged in the outer surface of the hollow piston 5, while the seals 7, 8 are located in the running surface of the clamping cylinder 4.

[0010] The pull rod 2 is anchored in the hollow piston 5 by a screw connection 9. For this purpose, the pull rod 2 has an external thread which, with a corresponding internal thread in an axial bore of the hollow piston 5, forms the screw connection 9. Upon axial displacement of the hollow piston 5 in the clamping cylinder 4, the hollow piston 5 thus carries the pull rod 2 with it in the axial direction. The screw connection 9 between the hollow piston 5 and the pull rod 2 is self-locking, so that an axial tensile load on the pull rod 2 does not lead to a loosening of the screw connection 9 and thus does not change the axial position of the pull rod 2 within the hollow piston 5.

[0011] In addition, the hollow piston cylinder 1 has a spherical disc 10, which has a flat support surface 11 on the clamping side and a spherical surface 12 on the opposite side. The spherical disc 10 allows the clamping cylinder 4 with the hollow piston 5 and the drawbar 2 to perform a slight pivoting movement when clamping on uneven clamping edges.

[0012] The hollow piston 5 and the drawbar 2 are driven hydraulically via a hydraulic connection 13, through which hydraulic oil can be introduced into a pressure chamber 14. When hydraulic oil is introduced into the pressure chamber 14, the hollow piston 5 is then moved upwards from the released starting position shown in the drawing into its clamped position.

[0013] To return the hollow piston 5 from its upper clamped position to the illustrated lower released starting position, the hollow piston cylinder 1 has a helical spring 15 that preloads the hollow piston 5 downward into its released starting position. The helical spring 15 is supported on the one hand by a circumferential collar of the hollow piston 5 and on the other hand by a housing cup 16, which is screwed into the top of the clamping cylinder 4.

[0014] It should also be mentioned that the pull rod 2 has a radially through transverse bore 17 at its upper end, which serves to lock and secure the pull rod 2 in the hollow piston cylinder 1. For this purpose, a radially through receiving bore 18 is also provided in the hollow piston 5. For locking, the pull rod 2 is then screwed into the hollow piston cylinder 1 until the receiving bore 18 in the hollow piston 5 is aligned with the transverse bore 17 in the pull rod 2. A locking bolt 19 can then be inserted, which passes through the receiving bore 18 and the transverse bore 17 and thereby locks the pull rod 2 so that the screw connection 9 cannot be loosened because the pull rod 2 cannot be rotated.

[0015] A disadvantage of this known hollow piston cylinder 1 is the fact that the hollow piston cylinder 1 is inflexible with regard to the size of the components to be clamped, since the functional dimension is predetermined by the design and cannot be changed. Description of the invention

[0016] The object of the invention is to create a correspondingly improved hollow piston cylinder which is flexible with regard to the possible functional dimensions.

[0017] This object is achieved by a hollow piston cylinder according to the invention according to the main claim.

[0018] The hollow piston cylinder according to the invention is generally used to clamp a component, which can be, for example, a tool or a workpiece.

[0019] In accordance with the known hollow piston cylinder described at the outset, the hollow piston cylinder according to the invention also has a clamping cylinder in which a hollow piston can be driven by a pressure medium (e.g. hydraulic oil) and can be displaced in the axial direction between a released starting position and a clamping position, wherein the hollow piston has a central axial bore.

[0020] In accordance with the known hollow piston cylinder described at the outset, the hollow piston cylinder according to the invention also has a pull rod which is anchored in the axial bore of the hollow piston, so that the hollow piston takes the pull rod with it in the axial direction when axially displaced by the pressure medium (e.g. hydraulic oil).

[0021] The invention now provides that the tie rod can be anchored in the axial bore of the hollow piston in different axial positions, whereby the functional dimension of the hollow piston cylinder can be flexibly adjusted.

[0022] In one variant of the invention, the desired axial position of the pull rod in the axial bore of the hollow piston can be adjusted in several stages. For example, two different axial positions of the pull rod in the hollow piston may be possible, with the user then being able to select one of the two axial positions, as will be described in detail below.

[0023] In another variant of the invention, however, the desired axial position of the pull rod is continuously adjustable in the axial bore of the hollow piston, making the hollow piston cylinder even more flexible in terms of the desired functional dimensions. The following describes the first variant of the invention mentioned above, in which the desired axial position of the pull rod is continuously adjustable in the axial bore of the piston.

[0024] In this first variant of the invention, the axial bore of the hollow piston has an internal thread, as is also the case with the known hollow piston cylinder described above. Here, too, the pull rod has a corresponding external thread, which then forms a screw connection with the internal thread in the axial bore of the hollow piston, anchoring the pull rod in the hollow piston. Various axial positions of the pull rod relative to the hollow piston can then be achieved by screwing the pull rod into the hollow piston to different depths, which then leads to a corresponding axial displacement of the pull rod relative to the hollow piston until the pull rod has reached the desired axial position relative to the hollow piston.

[0025] It should be noted that the screw connection between the pull rod on the one hand and the hollow piston on the other hand is preferably self-locking, so that a purely axial tensile load on the pull rod does not lead to a rotation of the pull rod relative to the hollow piston and therefore does not lead to a corresponding adjustment of the axial position of the pull rod relative to the hollow piston.

[0026] In this first variant of the invention, the pull rod has a plurality of locking engagements (e.g., transverse bores) distributed along the pull rod. To lock the pull rod in the desired axial position in the hollow piston, the hollow piston cylinder in this first variant of the invention has a locking element (e.g., locking pin) that engages with one of the locking engagements of the pull rod according to the desired axial position of the pull rod, thereby locking the pull rod in the desired axial position.

[0027] In a preferred embodiment of this first variant of the invention, the individual locking engagements of the pull rod are each transverse bores in the pull rod, which preferably extend radially through the pull rod. For example, the pull rod can have two radially continuous transverse bores that are arranged axially distributed in the pull rod and enable the adjustment of two different axial positions of the pull rod relative to the hollow piston. The locking element is preferably a locking bolt that is inserted into a receiving bore in the wall of the hollow piston and then passed through one of the transverse bores in the pull rod. The locking bolt then prevents rotation of the pull rod relative to the hollow piston, since this would lead to a corresponding adjustment of the axial position of the pull rod in the hollow piston.In this way, the first variant of the invention enables the adjustment and locking of different axial positions of the pull rod relative to the hollow piston, wherein the number of possible axial positions is equal to the number of transverse bores.

[0028] It should also be mentioned that a trigger ring is preferably attached to one end of the locking bolt to allow the locking bolt to be removed manually.

[0029] As already mentioned above, the invention also includes a second variant that allows for the continuous adjustment of the desired axial position of the pull rod in the axial bore of the hollow piston. This second variant will therefore be described in more detail below.

[0030] This second variant of the invention is characterized by a gear to anchor the pull rod in the axial bore of the hollow piston in various selectable axial positions.

[0031] In a preferred embodiment of the invention, this gear mechanism for anchoring the pull rod in the hollow piston is multi-stage, with several gear pairs that are kinematically connected in series. Preferably, the gear mechanism comprises a planetary gear and a screw drive that are kinematically connected in series.

[0032] The above-mentioned planetary gear preferably has as an operating element a manually rotatable and externally accessible ring gear with an internal toothing, which can be rotated by a user in order to adjust the desired axial position of the pull rod in the hollow piston, as will be described in detail below.

[0033] In addition, the planetary gear preferably has a centrally arranged rotatable sun gear with external teeth.

[0034] Between the sun gear and the ring gear, there is preferably at least one rotatable gear, which meshes externally with the internal toothing of the ring gear and internally with the external toothing of the sun gear, so that the planetary gear converts a manual rotation of the outer ring gear into a rotational movement of the central sun gear. It should be noted that the planetary gear operates in what is known as a two-shaft mode, since the rotational axes of the gears are fixed in the circumferential direction between the sun gear and the ring gear.

[0035] As already mentioned above, the transmission preferably comprises both a planetary gear and a screw drive. The screw drive is implemented by the sun gear having an axial bore with an internal thread, while the pull rod has an external thread. The external thread of the pull rod then forms the screw drive with the internal thread of the sun gear, which converts the rotational movement of the sun gear into an axial movement of the pull rod.

[0036] It should also be mentioned that the screw drive is preferably self-locking, so that an axial tensile load on the draw rod does not lead to an adjustment of the axial position of the draw rod relative to the hollow piston.

[0037] In this second invention variant with a planetary gear and a screw drive, the planetary gear first converts the manual rotation of the ring gear into the rotational movement of the sun gear, while the screw drive then converts the rotational movement of the sun gear into the axial movement of the pull rod long relative to the hollow piston in order to set the desired axial position of the pull rod relative to the hollow piston.

[0038] It should be noted that the ring gear is preferably axially fixed relative to the clamping cylinder, just as the at least one gear between the sun gear and the ring gear is axially and circumferentially fixed relative to the clamping cylinder, but is rotatably mounted.

[0039] The central sun gear, on the other hand, is preferably supported axially on the hollow piston and, together with the hollow piston, is axially displaceable relative to the clamping cylinder.

[0040] In this case, a first spring is preferably provided which preloads the sun gear axially against the hollow piston, wherein this first spring is preferably designed as a helical spring.

[0041] Furthermore, the pull rod in the hollow piston is preferably secured against rotation relative to the hollow piston. The user can thus adjust the desired axial position of the pull rod relative to the hollow piston by rotating the ring gear. To lock the ring gear in the desired rotational position, at least one pressure screw is preferably provided, which preferably presses axially against an end face of the ring gear. A detent can be located in the end face of the ring gear, with the at least one pressure screw then pressing into the detent on the ring gear to lock the ring gear in the respective rotational position. In the preferred embodiment of the invention, as many as six such pressure screws are seen, which press axially against the end face of the ring gear to lock it by means of a locking connection, with three of the six pressure screws being arranged on each side of the ring gear.

[0042] In the second variant of the invention described above, the hollow piston cylinder preferably has a first housing part that is firmly connected to the clamping cylinder, in particular by a screw connection. For example, the first housing part can be screwed into the clamping cylinder. Furthermore, the hollow piston cylinder preferably has a second housing part that is firmly connected to the first housing part. The ring gear is then preferably arranged in a slot between the first housing part and the second housing part and is accessible from the outside so that the user can rotate the ring gear. The at least one gear between the sun gear and the ring gear is rotatably mounted on an axle, wherein the axle of the at least one gear between the sun gear and the ring gear can be mounted on the one hand in the first housing part and on the other hand in the second housing part.

[0043] Furthermore, it should be mentioned that the at least one pressure screw for locking the ring gear can be screwed into an axial bore in the second housing part.

[0044] The above-mentioned first spring for the axial preload of the sun gear against the hollow piston can be supported on the one hand on the sun gear and on the other hand on the second housing part.

[0045] It should also be mentioned that the ring gear may have knurling on its outer surface to facilitate manual rotation of the ring gear by a user.

[0046] In the second variant of the invention described above, the axial bore in the hollow piston preferably has an oversize relative to the tie rod, so that the tie rod is anchored in the hollow piston indirectly via the threaded connection to the sun gear. In addition to the first variant of the invention described above, with a stepwise adjustability of the axial anchoring position of the tie rod in the hollow piston, and the second variant of the invention, also described above, with the stepless adjustability of the axial anchoring position of the tie rod in the hollow piston by means of a planetary gear, the invention also includes a third variant of the invention, which is described below.

[0047] In this third variant of the invention, the adjustment of the axial anchoring position of the pull rod in the hollow piston is also carried out by means of a gear mechanism. However, the gear mechanism does not comprise a multi-stage planetary gear mechanism as in the second variant of the invention, but rather a single-stage gear mechanism with only a single pair of meshing gears. The advantage of this third variant of the invention is the significantly lower manufacturing effort compared to the second variant with the planetary gear mechanism.

[0048] In the third variant of the invention, the screw drive preferably comprises a rotatable sleeve as an operating element, which is arranged in the hollow piston, wherein the sleeve is rotatable relative to the hollow piston but axially fixed in the hollow piston. This sleeve has an internal thread which, together with a corresponding external thread in the outer surface of the pull rod, forms the screw drive. This means that a rotational movement of the sleeve is converted into a corresponding axial movement of the pull rod due to the threaded connection between the sleeve and the pull rod. Due to the aforementioned axial anchoring of the sleeve in the hollow piston, a rotational movement of the sleeve leads to a corresponding change in the axial anchoring position of the pull rod in the hollow piston.

[0049] It should be noted that in the third variant of the invention, the screw drive is preferably self-locking, so that an axial load on the screw drive does not lead to a rotational movement of the sleeve relative to the draw rod.

[0050] The sleeve preferably protrudes downwards in the axial direction from the clamping cylinder, allowing an operator to rotate the sleeve there. To facilitate this rotation by the operator, the sleeve preferably has knurling on its outer surface at its protruding end. This allows the operator to apply a higher torque to the sleeve.

[0051] As already described above, the rotatable sleeve is anchored axially in the hollow piston, so that an axial movement of the sleeve leads to a corresponding axial movement of the hollow piston, and vice versa. For this axial anchoring of the sleeve in the hollow piston, the sleeve preferably has an annular groove in its outer surface, into which a grub screw engages, which is guided in a radial bore in the hollow piston.

[0052] Furthermore, the third variant of the invention preferably provides a clamping ring to limit the axial adjustment range of the drawbar relative to the hollow piston. The clamping ring is preferably clamped onto the drawbar on the clamping side of the hollow piston. For this purpose, the clamping ring preferably has at least one radial bore into which a grub screw is screwed. The end of the grub screw presses against the outer surface of the drawbar, thereby clamping the clamping ring onto the drawbar.

[0053] Furthermore, within the scope of the invention there is the possibility of displaying the respective axial position of the pull rod relative to the hollow piston on a scale so that the user can immediately see which functional dimension is set. For this purpose, the pull rod preferably projects axially out of the clamping cylinder opposite the clamping side. At its protruding end, the pull rod then carries the aforementioned scale in its outer surface, which extends in the axial direction and, in the released starting position of the hollow piston, indicates the axial position in which the pull rod is locked in the hollow piston. The scale can be located directly in the pull rod or in an end piece that is screwed onto the end of the pull rod.

[0054] In general, it should also be mentioned that the hollow piston cylinder according to the invention can be either single-acting or double-acting.

[0055] In the single-acting variant, the hollow piston cylinder has a first pressure medium connection for supplying a pressure medium (e.g., hydraulic oil) that serves to clamp the hollow piston from the released starting position to the clamped position. A second spring (e.g., a coil spring) acts on the hollow piston to return it from the clamped position to the released starting position.

[0056] In the double-acting version, however, the hollow piston cylinder has two pressure ports for supplying a pressure medium (e.g., hydraulic oil). The hollow piston is thus driven by the pressure medium in both directions (clamping and releasing).

[0057] In general, it should also be mentioned that the axial bore in the hollow piston is preferably an axially continuous through-bore, which applies to both variants of the invention.

[0058] Furthermore, it should also be mentioned in general for both variants of the invention that the hollow piston cylinder is preferably designed such that it can exert a maximum axial tensile force and / or a maximum axial compressive force of at least 1 kN, 2 kN, 5 kN, 10 kN, 20 kN, 50 kN, 100 kN, 150 kN, 200 kN or 250 kN on the pull rod.

[0059] As already mentioned above, the pressure medium for driving the hollow piston cylinder according to the invention can be hydraulic oil. However, with regard to driving the hollow piston cylinder, the invention is not limited to hydraulic oil as the pressure medium, but can also be implemented using compressed air as the pressure medium, for example.

[0060] In general, it should also be mentioned that the hollow piston cylinder is preferably designed for an operating pressure of the pressure medium of at least 20 bar, 50 bar, 100 bar, 200 bar, 300 bar or 400 bar.

[0061] The axial position of the pull rod relative to the hollow piston is preferably adjustable over an axial range of at least 10 mm, 20 mm, 30 mm, 50 mm or 100 mm.

[0062] In one embodiment, the hollow piston cylinder has a spherical disc which has a flat support surface on the clamping side and a convexly curved surface on the opposite side, on which the clamping cylinder rests, so that the clamping cylinder with the pull rod can perform a pivoting movement relative to the spherical disc and the clamping surface.

[0063] Furthermore, the tension rod can be a T-slot screw at its distal end to anchor the tension rod in a T-slot of the component to be clamped.

[0064] Finally, it should be mentioned that the hollow piston in the clamping cylinder can have an axial stroke of at least 2 mm, 5 mm, or at least 10 mm.

[0065] Other advantageous developments of the invention are characterized in the subclaims or are explained in more detail below together with the description of the preferred embodiments of the invention with reference to the figures. Brief description of the drawings

[0066] Figure 1 shows a sectional view through a known hollow piston cylinder according to the prior art.

[0067] Figure 2A shows a perspective view of a hollow piston cylinder according to the invention according to a first variant of the invention.

[0068] Figure 2B shows a sectional view through the hollow piston cylinder according to the invention according to Figure 2A.

[0069] Figure 3A shows a perspective view of a hollow piston cylinder according to the invention according to a second variant of the invention.

[0070] Figure 3B shows a longitudinal sectional view through the hollow piston cylinder according to Figure 3A.

[0071] Figure 3C shows a cross-sectional view through the hollow piston cylinder according to Figures 3A and 3B.

[0072] Figure 4 shows a perspective view of the ring gear of the second variant of the invention according to Figures 3A-3C with pressure screws for locking the ring gear in a rotational position.

[0073] Figure 5A shows a perspective view of a third variant of the invention with a single-stage screw drive for adjusting the axial anchoring position of the pull rod in the hollow piston.

[0074] Figure 5B shows a side view of the third variant of the invention according to Figure 5A.

[0075] Figure 5C shows a bottom view of the third variant of the invention according to Figures 5A and 5B.

[0076] Figure 5D shows a sectional view of the third variant of the invention along the section line AA in Figure 5C.

[0077] Detailed description of the drawings

[0078] The following describes the first variant of the hollow piston cylinder 1 according to the invention, as shown in Figures 2A and 2B. This variant of the invention largely corresponds to the known hollow piston cylinder 1, as described above and shown in Figure 1. To avoid repetition, reference is therefore made to the above description of Figure 1, with the same reference numerals being used for corresponding details.

[0079] A special feature of this embodiment according to the invention is that in addition to the transverse bore 17, a further transverse bore 20 is provided in the pull rod 2, wherein the two transverse bores 17, 20 are arranged in different axial positions in the pull rod 2 and each pass radially through the pull rod 2.

[0080] The user can therefore fix the pull rod 2 in the hollow piston 5 in two different axial positions by selecting one of the two transverse bores 17, 20. In the drawing, the locking pin 19 is inserted into the transverse bore 20 in the pull rod 2, so that the functional dimension is relatively small. The desired transverse bore 17, 20 is selected by screwing the pull rod 2 into the hollow piston 5 before locking it using the locking pin 19 until the receiving bore 18 in the wall of the hollow piston 5 is aligned with the respective transverse bore 17 or 19, so that the locking pin 19 can then be inserted.

[0081] A further special feature of this embodiment is that a release ring 21 is attached to the end of the locking bolt 19, which makes it easier for the user to pull the locking bolt 19 out of the respective transverse bore 17 or 20.

[0082] The above-described variant of the invention of a hollow piston cylinder according to the invention thus enables the adjustment of two different functional dimensions by anchoring the locking bolt 19 optionally in the transverse bore 17 or in the transverse bore 20.

[0083] The second variant of the invention of the hollow piston cylinder 1 according to the invention, which is shown in Figures 3A-3C, is now described. This second variant of the invention also partially corresponds to the known hollow piston cylinder 1 described above and shown in Figure 1, so that to avoid repetition, reference is again made to the above description, with the same reference numerals being used for corresponding details. The second variant of the invention is characterized in that the axial position of the pull rod 2 relative to the hollow piston 5 is continuously adjustable. For this purpose, the second variant of the invention has a planetary gear and a screw drive.

[0084] The planetary gear initially comprises a ring gear 22 as an operating element, which is accessible from the outside and can be rotated by a user to set the desired axial position, as will be described in detail below.

[0085] In addition, the planetary gear comprises a central sun gear 23, which is arranged coaxially to the ring gear 22 and is also rotatable.

[0086] Between the outer ring gear 22 and the inner sun gear 23 there are three gears 24, 25, 26, each of which is rotatably mounted, whereby the axes of rotation of the gears 24-26 are fixed in the circumferential direction, so that the planetary gear works in the so-called two-shaft operation.

[0087] The gears 24-26 are each rotatably mounted on a rotational axis 27, wherein the rotational axis 27 is mounted on the one hand in a housing part 28 and on the other hand in a housing part 29.

[0088] The planetary gear thus converts a rotation of the ring gear 22 by the user into a rotation of the sun gear 23.

[0089] In addition, the transmission has a screw drive formed by the sun gear 23 and the pull rod 2. For this purpose, the pull rod 2 has an external thread that engages an internal thread in an axial bore of the sun gear 23. Due to this threaded connection, rotation of the sun gear 23 leads to a corresponding axial displacement of the pull rod 2 relative to the hollow piston 5.

[0090] The planetary gear thus initially converts a rotation of the ring gear 22 by the user into a corresponding rotational movement of the sun gear 23. The screw drive then converts the rotational movement of the sun gear 23 into a corresponding axial movement of the pull rod 2. By rotating the ring gear 22, the user can thus continuously lock the pull rod 2 in a desired axial position in the hollow piston 5.

[0091] It should be noted that the sun gear 23 falls axially on the hollow piston 5, so that the hollow piston 5 carries the sun gear 23 and thus also the pull rod 2 anchored in the sun gear 23 in the axial direction.

[0092] It should also be noted that an end piece 30 is screwed onto the end of the pull rod 2, which protrudes axially from the housing part 29 and is thus visible from the outside. A scale 31 is located on the outer surface of the end piece 30, which allows the user to determine the set functional dimension in the released initial position, since the end piece 30 then protrudes correspondingly far from the second housing part 29.

[0093] Furthermore, it should be mentioned that the sun gear 23 is axially displaceable and is axially preloaded against the hollow piston 5 by a helical spring 32.

[0094] It should also be mentioned that the ring gear 22 can be locked in the desired rotational position. This is achieved by six pressure screws 33, which press against the ring gear 22 in the axial direction (see Fig. 4). The ring gear 22 has a notch on its end face, into which the pressure screws 33 engage to lock the ring gear 22 in the desired rotational position. Three of the six pressure screws are arranged on each side of the ring gear 22.

[0095] Finally, it should be mentioned that the ring gear 22 has a knurling 34 in its outer surface, which makes it easier for the user to rotate the ring gear 22.

[0096] The third variant of the invention, illustrated in Figures 5A-5D, will now be described. This third variant of the invention partially corresponds to the second variant of the invention described above, as illustrated in Figures 3A-3C and 4. To avoid repetition, reference is therefore made to the above description of the second variant of the invention according to Figures 3A-3C and 4, with the same reference numerals being used for corresponding details.

[0097] In this third variant of the invention, the axial anchoring position of the pull rod 2 in the hollow piston 5 is also adjusted continuously by means of a gear mechanism. However, the gear mechanism is not a multi-stage planetary gear mechanism as in the second variant of the invention according to Figures 3A-3C and 4, but rather a single-stage gear mechanism with a screw drive 35.

[0098] The screw drive 35 initially comprises a rotatable sleeve 36, which is arranged coaxially in the hollow piston 5. The rotatable sleeve 36 is axially fixed in the hollow piston 5, so that an axial movement of the sleeve 36 leads to a corresponding axial movement of the hollow piston 5 and vice versa. However, an axial load on the screw drive 35 does not lead to a rotation of the sleeve 36 relative to the draw rod 1, since the screw drive 35 is self-locking.

[0099] The sleeve 36 has a circumferential annular groove 37 in its outer surface, into which a grub screw 38 engages, which is screwed into a radial bore in the hollow piston 5. In the position according to Figure 5D, the grub screw 38 engages with its radially inner end in the annular groove 37 of the sleeve 36 and thereby fixes the sleeve 36 in the axial direction in the hollow piston 5.

[0100] Furthermore, the sleeve 36 has an internal thread that engages with a corresponding external thread of the pull rod 2 and forms the screw drive 35. The screw drive 35 ensures that a rotation of the sleeve 36 is converted into a corresponding axial movement of the pull rod 2 relative to the sleeve 36 and thus also relative to the hollow piston 5.

[0101] The lower end of the sleeve 36 protrudes from the clamping cylinder 4 and has a knurling 39 there to facilitate manual turning of the sleeve 36. The knurling 39 allows the operator to apply a greater torque to the sleeve 36.

[0102] Furthermore, it should be mentioned that the pull rod 2 projects in the axial direction from the sleeve 36 and carries the scale 31 already mentioned there, so that the user can immediately see which functional dimension is set.

[0103] Furthermore, in this third variant of the invention, a clamping ring 40 is provided, which limits the axial adjustment range of the pull rod 2 relative to the hollow piston 5. The clamping ring 40 surrounds the pull rod 2 in a ring shape on the clamping side of the hollow piston 5. Several radial bores are arranged in the clamping ring 40, into each of which a grub screw 41 is screwed. In the position according to Figure 5D, the grub screw 41 presses into the thread in the outer surface of the pull rod 2, whereby the clamping ring 40 is clamped firmly onto the pull rod 2. The pull rod 2 can therefore only be adjusted in the axial direction relative to the hollow piston 5 until the clamping ring 40 abuts the upper end face of the hollow piston 5, as shown in Figure 5D.

[0104] The invention is not limited to the preferred embodiments described above. Rather, the invention also encompasses variants and modifications that also utilize the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and features of the subclaims, independently of the respective claims referred to, and in particular even without the features of the main claim. The invention thus encompasses various aspects of the invention that enjoy independent protection.

[0105] List of reference symbols

[0106] 1 hollow piston cylinder

[0107] 2 drawbar

[0108] 3 T-slot head of the drawbar

[0109] 4 clamping cylinders

[0110] 5 hollow pistons

[0111] 6 Seal in the outer surface of the hollow piston

[0112] 7 , 8 Seals in the running surface of the clamping cylinder

[0113] 9 Screw connection between hollow piston and pull rod

[0114] 10 spherical disc

[0115] 11 Support surface of the spherical disc

[0116] 12 Spherical surface of the spherical disc

[0117] 13 Hydraulic connection for clamping the hollow piston cylinder

[0118] 14 Pressure chamber of the clamping cylinder

[0119] 15 Coil spring for releasing the hollow piston cylinder

[0120] 16 Housing pot

[0121] 17 Cross hole in the pull rod

[0122] 18 Mounting hole in the hollow piston for the locking bolt

[0123] 19 locking bolts

[0124] 20 Cross hole in the pull rod

[0125] 21 Trigger ring for pulling out the locking bolt

[0126] 22 Ring gear of the helical gear

[0127] 23 Sun gear of the helical gear

[0128] 24-26 gears of the helical gear between the ring gear and the sun gear

[0129] 27 axes of the gears

[0130] 28 Housing part on the clamping cylinder

[0131] 29 Housing part on the clamping cylinder

[0132] 30 End piece of the pull rod

[0133] 31 Scale to display the set functional dimension

[0134] 32 Coil spring for preloading the sun gear against the hollow piston

[0135] 33 pressure screws for locking the ring gear in a locking position

[0136] 34 Knurling

[0137] 35 screw drive

[0138] 36 Sleeve 37 Ring groove

[0139] 38 grub screw

[0140] 39 Knurling in the outer surface of the sleeve

[0141] 40 Clamping ring 41 Grub screw in the clamping ring

Claims

CLAIMS 1. Hollow piston cylinder (1) for clamping a component, in particular a tool or a workpiece, with a) a clamping cylinder (4), b) a hollow piston (5) which is displaceable in the clamping cylinder (4) in the axial direction between a released starting position and a clamping position and is driven by a pressure medium and has a central axial bore, and c) a pull rod (2) which projects from the clamping cylinder (4) on a clamping side and is anchored in the axial bore of the hollow piston (5) so that the hollow piston (5) entrains the pull rod (2) in the axial direction upon axial displacement by the pressure medium, characterized in that d) the pull rod (2) can be anchored in the axial bore of the hollow piston (5) in various axial positions.

2. Hollow piston cylinder (1) according to claim 1, characterized in that a) the desired axial position of the pull rod (2) in the axial bore of the hollow piston (5) is adjustable in several stages, or b) the desired axial position of the pull rod (2) in the axial bore of the hollow piston (5) is continuously adjustable.

3. Hollow piston cylinder (1) according to one of the preceding claims, characterized in that a) the axial bore of the hollow piston (5) has an internal thread, b) the pull rod (2) has an external thread, c) the external thread of the pull rod (2) forms a screw connection (9) with the internal thread of the axial bore of the hollow piston (5), which screw connection anchors the pull rod (2) in the hollow piston (5), and d) the screw connection (9) allows the different axial positions of the pull rod (2) relative to the hollow piston (5) by screwing the pull rod (2) into the hollow piston (5) to different extents, e) the screw connection (9) of the pull rod (2) and the hollow piston (5) preferably is self-locking, so that a purely axial tensile load on the pull rod (2) does not lead to a rotation of the pull rod (2) relative to the hollow piston (5) and therefore also does not lead to a corresponding adjustment of the axial position of the pull rod (2) relative to the hollow piston (5).

4. Hollow piston cylinder (1) according to claim 3, characterized in that a) the pull rod (2) has a plurality of locking engagements (17, 20) which are arranged distributed along the pull rod (2), and b) in order to lock the pull rod (2) in the hollow piston (5) in one of the different axial positions, a locking element (19) is provided which engages in one of the locking engagements (17, 20) of the pull rod (2) in accordance with the desired axial position of the pull rod (2).

5. Hollow piston cylinder (1) according to claim 4, characterized in that a) the individual locking engagements (17, 20) of the pull rod (2) are each transverse bores (17, 20) in the pull rod (2), which preferably pass radially through the pull rod (2), b) the locking element (19) is a locking pin (19), c) the hollow piston (5) has a receiving bore (18) in its wall for the locking pin (19), and d) the locking pin (19) is inserted into the receiving bore (18) in the wall of the hollow piston (5) for locking the pull rod (2) in one of the axial positions and is guided through one of the transverse bores (17, 20) in the pull rod (2), e) a withdrawal ring (21) is attached to one end of the locking pin (19). in order to be able to remove the locking bolt (19) manually.

6. Hollow piston cylinder (1) according to claim 1 or 2, characterized by a gear for anchoring the pull rod (2) in the axial bore of the hollow piston (5) in various selectable axial positions.

7. Hollow piston cylinder (1) according to claim 6, characterized in that a) the gear is multi-stage with several gear pairs (22-26) which are kinematically connected in series, and / or b) that the gear has a planetary gear (22-26) and a screw drive (23, 2) which are kinematically connected in series.

8. Hollow piston cylinder (1) according to claim 7, characterized in that a) the planetary gear (22-26) has, as an operating element, a manually rotatable and externally accessible ring gear (22) with internal teeth, b) the planetary gear (22-26) has a centrally arranged rotatable sun gear (23) with external teeth, c) the planetary gear (22-26) has at least one rotatable gear (24-26) which engages externally with the internal teeth of the ring gear (22) and internally with the external teeth of the sun gear (23), and d) the planetary gear (22-26) converts a manual rotation of the outer ring gear (22) into a rotary movement of the central sun gear (23).

9. Hollow piston cylinder (1) according to claim 8, characterized in that a) the sun gear (23) has an axial bore with an internal thread, b) the pull rod (2) has an external thread, c) the external thread of the pull rod (2) engages in the internal thread of the sun gear (23), so that the pull rod (2) with the sun gear (23) forms the screw drive which converts a rotary movement of the sun gear (23) into an axial movement of the pull rod (2), d) the screw drive is preferably self-locking, so that an axial tensile load on the pull rod (2) does not lead to an adjustment of the axial position of the pull rod (2) relative to the hollow piston (5).

10. Hollow piston cylinder (1) according to claim 9, characterized in that a) the planetary gear (22-26) converts the manual rotation of the ring gear (22) into the rotary movement of the sun gear (23), and b) the screw drive converts the rotary movement of the sun gear (23) into the axial movement of the pull rod (2) relative to the hollow piston (5) in order to set the desired axial position of the pull rod (2) relative to the hollow piston (5).

11. Hollow piston cylinder (1) according to one of claims 8 to 10, characterized in that a) the ring gear (22) is axially fixed relative to the clamping cylinder (4), and / or b) the at least one gear (24-26) is axially and circumferentially fixed and rotatably mounted between the sun gear (23) and the ring gear (22) relative to the clamping cylinder (4), and / or c) the sun gear (23) is axially supported on the hollow piston (5) and, together with the Hollow piston (5) is axially displaceable relative to the clamping cylinder (4), and / or d) that a first spring (32) prestresses the sun gear (23) axially against the hollow piston (5), in particular a first helical spring (32), and / or e) that the pull rod (2) in the hollow piston (5) is secured against rotation relative to the hollow piston (5).

12. Hollow piston cylinder (1) according to one of claims 8 to 11, characterized in that a) at least one pressure screw (33) is provided to lock the ring gear (22) in the respective rotational position, b) the at least one pressure screw (33) preferably presses axially against an end face of the ring gear (22), and c) the end face of the ring gear (22) preferably has a detent in the circumferential direction and the at least one pressure screw (33) presses into the detent on the ring gear (22) in order to lock the ring gear (22) in the respective rotational position.

13. Hollow piston cylinder (1) according to one of claims 8 to 12, characterized in that a) the hollow piston cylinder (1) has a first housing part (28) which is firmly connected to the clamping cylinder (4), in particular by a screw connection, in particular with an internal thread in the screw cylinder and an external thread on the first housing part (28), so that the first housing part (28) is screwed into the clamping cylinder (4), and / or b) the hollow piston cylinder (1) has a second housing part (29) which is firmly connected to the first housing part (28), and / or c) the ring gear (22) is arranged in a slot between the first housing part (28) and the second housing part (29) and is accessible from the outside, and / or d) the at least one gear (24-26) is rotatably mounted on an axle (27) between the sun gear (23) and the ring gear (22),and / or e) that the axis (27) of the at least one gear (24-26) is mounted between the sun gear (23) and the ring gear (22) on the one hand in the first housing part (28) and on the other hand in the second housing part (29), and / or f) that the pressure screw (33) for locking the ring gear (22) is screwed into an axial bore in the second housing part (29), and / or g) that the first spring (32) for the axial preload of the sun gear (23) against the hollow piston (5) is supported on the one hand on the sun gear (23) and on the other hand on the second housing part (29), and / or, h) that the ring gear (22) has a knurling (34) in its outer circumferential surface in order to facilitate the manual rotation of the ring gear (22), and / or i) that the axial bore in the hollow piston (5) has an oversize compared to the pull rod (2), so that the pull rod (2) is anchored in the hollow piston (5) indirectly via the threaded connection with the sun gear (23).

14. Hollow piston cylinder according to claim 6, characterized in that a) the gear is a single-stage screw drive (35) which converts a rotary movement of a sleeve (36) serving as an operating element into an axial movement of the pull rod (2) relative to the hollow piston (5), b) the screw drive (35) is preferably self-locking, so that an axial load on the screw drive (35) does not lead to a rotary movement of the sleeve (36) relative to the pull rod (2) and thus also not to an axial relative movement of the pull rod (2) relative to the sleeve (36).

15. Hollow piston cylinder (1) according to claim 14, characterized in that a) the sleeve (36) is arranged in the hollow piston (5), wherein the sleeve (36) serves to adjust the axial anchoring position of the pull rod (2) in the hollow piston (5), b) the sleeve (36) is rotatable relative to the hollow piston (5) in order to adjust the axial anchoring position of the pull rod (2) in the hollow piston (5), c) the sleeve (36) is axially fixed in the hollow piston (5) so that an axial relative movement of the sleeve (36) relative to the hollow piston (5) is prevented, d) the sleeve (36) has an internal thread, e) the pull rod (2) has an external thread in its outer surface, f) the sleeve (36) engages with its internal thread in the external thread of the pull rod (2) and forms the threaded drive (35), so that a rotational movement of the sleeve (36) determines the axial position of the pull rod (2) relative to the sleeve (36) and thus also relative to the hollow piston (5),g) that the sleeve (36) preferably projects in the axial direction from the clamping cylinder (4) and has a knurling (39) on its outer surface., 16. Hollow piston cylinder according to claim 15, characterized in that a) the sleeve (36) has an annular groove (37) in its outer surface, b) the hollow piston (5) has a radial bore with a screw thread, and c) a grub screw (38) is screwed into the radial bore of the hollow piston (5), which engages with its radially inner end into the annular groove (37) in the outer surface of the sleeve (36) and thereby fixes the sleeve (36) axially in the hollow piston (5).

17. Hollow piston cylinder according to one of claims 14 to 16, characterized in that a) a clamping ring (40) is provided to limit the axial adjustment range of the pull rod (2) relative to the hollow piston (5), b) the clamping ring (40) is clamped onto the pull rod (2), c) the clamping ring (40) for clamping onto the pull rod (2) preferably has a radial bore with a screw thread into which a grub screw (41) is screwed, which presses with its radially inner end onto the outer circumferential surface of the pull rod (2) and thereby clamps the clamping ring (40) onto the pull rod (2), d) the clamping ring (40) is preferably clamped onto the pull rod (2) on the clamping side of the hollow piston (5).

18. Hollow piston cylinder (1) according to one of the preceding claims, characterized in that a) the pull rod (2) projects axially out of the clamping cylinder (4) opposite the clamping side, and b) the pull rod (2) has a scale (31) on its end projecting out of the clamping cylinder (4) opposite the clamping side in its outer circumferential surface, which scale extends in the axial direction and indicates, in the released initial position of the hollow piston (5), in which axial position the pull rod (2) is locked in the hollow piston (5), c) the scale (31) is preferably located on the circumferential surface of an end piece (30) which is screwed onto the end of the pull rod (2).

19. Hollow piston cylinder (1) according to one of the preceding claims, characterized in that a) the hollow piston cylinder (1) is single-acting with a1) a first pressure medium connection (13) for supplying the pressure medium for clamping the hollow piston (5) from the released starting position into the clamped position and a2) a second spring for returning the hollow piston (5) from the clamped position into the released starting position, in particular as a second helical spring, wherein the second spring is preferably supported on the one hand on the hollow piston (5) and on the other hand on the first housing part, or b) the hollow piston cylinder (1) is double-acting with bl) a first pressure medium connection (13) for supplying the pressure medium for clamping the hollow piston (5) from the released starting position into the clamping position and b2) a second pressure medium connection for supplying a pressure medium for returning the hollow piston (5) from the clamping position into the released starting position.

20. Hollow piston cylinder (1) according to one of the preceding claims, characterized in that a) the axial bore in the hollow piston (5) is an axially continuous through-bore, and / or b) the hollow piston cylinder (1) is designed to exert a maximum axial tensile force and / or a maximum axial compressive force of at least 1 kN, 2 kN, 5 kN, 10 kN, 20 kN, 50 kN, 100 kN, 150 kN, 200 kN or 250 kN on the pull rod (2), and / or c) the pressure medium is hydraulic oil or compressed air, and / or d) the hollow piston cylinder (1) is designed for an operating pressure of the pressure medium of at least 20 bar, 50 bar, 100 bar, 200 bar, 300 bar or 400 bar, and / or e) the axial position of the pull rod (2) relative to the hollow piston (5) over an axial range of at least 10 mm, 20 mm, 30 mm, 50 mm or 100 mm, and / or f) that the hollow piston cylinder (1) has a spherical disc (10),which has a flat clamping surface (11) on the clamping side and a convexly curved surface (12) on the opposite side, on which the clamping cylinder (4) rests, so that the clamping cylinder (4) with the drawbar (2) can perform a pivoting movement relative to the spherical disc (10) and the clamping surface (11), and / or g) that the drawbar (2) is a T-slot screw at its distal end in order to anchor the drawbar (2) in a T-slot of the component to be clamped, and / or h) that the hollow piston (5) in the clamping cylinder (4) has an axial stroke of at least 2 mm, 5 mm, or at least 10 mm, in particular an axial stroke of 12 mm.

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