FASTENING DEVICE FOR A WORKPIECE

Description

Technical field

[0001] The invention relates to a fastening device for fixing a workpiece to a flat, upright support element, with a main body to which two clamping jaws are movably attached relative to each other, which extend below the main body and can be moved towards each other by means of a clamping means accessible from the top of the main body.

[0002] Another aspect of the proposal described here concerns a method for processing a flat workpiece on a waterjet cutting system with a worktable that has a plurality of flat, upright support elements as described above, arranged at intervals from one another, wherein the workpiece is placed on a plurality of spacer elements distributed over the surface of the workpiece. The proposal described here further relates to a spacer element and a set comprising at least one fastening device and a plurality of spacer elements for fixing a workpiece to a worktable with a flat, upright support element. State of the art

[0003] Fixing workpieces during machining ensures precise and accurate positioning. This development is particularly suitable for workpiece fixation during mechanical machining, especially when cutting workpieces with a water jet. In water jet cutting, the workpieces rest on the narrow edges of flat support elements, which are essentially oriented in a vertical plane and arranged in a basin that collects the water from the jet. The support elements are replaceable because they are damaged by the water jet.

[0004] A holding device for fixing a workpiece in a waterjet cutting system is known from publication CN 113442205 A. The holding device comprises a first guide rail, a second guide rail, and a plurality of clamping devices. The first and second guide rails are placed on the support elements of the waterjet cutting system and fastened to them by means of wing nuts. At least one clamping device for fixing a workpiece to be processed is detachably attached to each of the first and second guide rails. The clamping device comprises a compression spring and a lever that is pressed onto the workpiece by means of the compression spring. The fastening device is intended to enable the quick clamping and unclamping of workpieces of different sizes and shapes in a waterjet cutting system.

[0005] Publication AT 10 883 U1 describes a fastening device with a clamping mechanism, in particular a flower box holder for a windowsill / sheet metal. Publication GB 215 349 A describes a screw clamp with three clamping jaws that can be pressed against a workpiece. Summary of the invention

[0006] The invention is based on the objective of providing an easy-to-use fastening device. Preferably, the fastening device should be simple and inexpensive, be securely, quickly, and flexibly attachable to a workbench, and securely and easily fix a workpiece to the workbench.

[0007] According to the invention, this problem is solved by a fastening device having the features of the independent claim. Advantageous embodiments are described in the dependent claims.

[0008] The fastening device described here for fixing a workpiece to a flat, upright support element comprises a main body to which two clamping jaws are movably attached relative to each other, which extend below the main body and can be moved towards each other by means of a clamping means accessible from the top of the main body.

[0009] The flat, upright support elements are typically vertically oriented sheets and are also known as wear plates. As mentioned above, the worktable of a waterjet cutting system has a basin for collecting the water, containing multiple such support elements. These elements are essentially arranged in vertical planes, and their upper edge, furthest from the worktable, forms the support for a workpiece. Alternatively, the support element can also be a bar, a rib, or a grid, with the bar, rib, or grid having an edge pointing away from the worktable on which the workpiece rests.

[0010] The clamping device can be attached to the support element by means of the clamping jaws in such a way that the main body is placed against the edge of the support element furthest from the worktable and secured to it with the clamping jaws. Often, the workpiece to be machined is flat and plate-shaped and is oriented horizontally for machining. For this purpose, the main body is placed against the upper edge of the support element furthest from the worktable, and the clamping jaws rest against two side surfaces of the support element adjacent to this edge, clamping the support element in place. The two clamping jaws are movably attached to the main body relative to each other and protrude at least partially from beneath the main body. The clamping jaws are moved towards each other by means of a clamping device accessible from the top of the main body.The jaws are moved away from each other to move from a clamping position with a small gap between them to a release position with a large gap between them. In the clamping position, the fixture is firmly clamped to the support element, and in the release position, it can be removed. The top of the main body is the side facing away from the support element. For example, the workpiece to be machined can be placed on the top. The jaws can be moved together by means of a single clamping device acting on both jaws. Alternatively, two separate clamping devices—for example, identical ones—accessible from the top of the main body can be provided, with each of these two clamping devices moving one jaw between the clamping position and the release position.

[0011] To solve the problem according to the invention, the fastening device has a holding element which is arranged above the main body, that is, on the side of the main body furthest from the clamping jaws, and which is movable towards the main body by means of a clamping device. In other words, a holding element is proposed with which a workpiece to be machined, and arranged at least partially below the holding element, can be pressed against the main body or against the support element. The holding element is particularly flat and projects upwards by less than 2.5 mm, preferably less than 2 mm, above the top surface of the workpiece. The holding element can be smaller than the top surface of the main body or substantially congruent with it. In both of these cases, the workpiece to be fixed can be pressed by the holding element against the top surface of the main body.Alternatively, the holding element can be larger than the top of the main body. In this case, the holding element projects laterally beyond the main body and can press the workpiece to be fixed against the support element and / or against the top of the main body. The force with which the workpiece is pressed against the main body and / or against the support element is generated by the clamping device. ToFor this purpose, the clamping device pushes or pulls the retaining element in the direction of the main body. The clamping device is connected to the main body by a first section. This connection can be material-fit, positive-locking, and / or force-locking. The clamping device is connected to the retaining element by a second section. This connection can also be material-fit, positive-locking, and / or force-locking. A plurality of clamping devices—for example, identical ones—with the features described above can also be used, allowing the retaining element to be moved towards the main body. The clamping device or the plurality of clamping devices can also be designed, arranged, and connected to the retaining element in such a way that no part of the fastening device protrudes more than 2.5 mm, preferably 2 mm, beyond the side of the workpiece facing away from the main body.Overall, the clamping device is thus essentially positioned below the workpiece being processed. A tool for processing the workpiece, particularly a nozzle of a waterjet cutting system, is often moved a few millimeters above the side of the workpiece facing away from the main body. This distance is often less than 3 mm. Due to the design of the clamping device, which is primarily positioned below the workpiece and has only a flat retaining element above it, the tool can move freely above the workpiece. This reduces or eliminates the risk of the tool colliding with and being damaged by the clamping device during movement above the workpiece.

[0012] In practice, a gap can be formed between the clamping jaws in a first plane, and a gap in a second plane between the holding element and the top of the main body, with the second plane being perpendicular to the first. These two perpendicular gaps allow workpieces to be fixed in a horizontal orientation using the clamping device when the device is attached from above to a support element that projects vertically from a horizontal worktable. This is the case, for example, with waterjet cutting systems where the worktable has a tray or basin to collect the water, in which the flat support elements extend vertically upwards. The clamping device can also be used with flat support elements that do not extend exactly vertically.In this case, "below" means near the workbench and "above" means away from the workbench.

[0013] In practice, the clamping device can be a clamping screw. The clamping screw has a connecting element and a threaded section. The connecting element, also called the drive, serves to create a positive connection with a tool for turning the clamping screw, such as a screwdriver or wrench. The connecting element can be slotted or Phillips-shaped, or it can be shaped like an internal hexagon or a six-point socket (TORX®). It can also be a square or hexagonal projection for a wrench. The threaded section of the clamping screw protrudes through a bore in the main body, which has an internal thread. Using the connecting element located on the top of the main body, the clamping screw can be turned from above, thus being screwed into and out of the bore. The clamping screw can also have a drive lug.The drive pin is positioned at the end of the threaded section opposite the connecting element. The clamping screw engages with the drive pin in a recess optionally provided in the clamping jaws. The recesses in the clamping jaws are essentially geometrically complementary to the drive pin. The recesses can be located on the facing sides of the clamping jaws, so that these sides of the jaws abut the clamping screw located in the main body. When the clamping screw is screwed into the internal thread of the bore in the main body from above, pressure is exerted on the clamping jaws via the drive pin, forcing the jaws apart into the release position.By unscrewing the clamping screw upwards from the main body, a tensile force is exerted on the clamping jaws via the drive pin, which moves the clamping jaws towards each other in the clamping position. However, a drive pin on the clamping screw is not strictly necessary. For example, the clamping screw can have a stub or a point at the end of the threaded section opposite the connecting element, with the clamping screw bearing against an edge of each of the two clamping jaws that faces the surface of the main body. In this case, screwing the clamping screw into the internal thread of the bore in the main body from above exerts pressure on the clamping jaws, forcing them apart into the release position.Moving the clamping jaws into the clamping position can be achieved, for example, by unscrewing the clamping screw upwards from the main body and using elastic springs that press the clamping jaws together. Optionally, two clamping screws can be used, each with a drive, a stub, or a point, and interacting with one of the two clamping jaws. For example, one clamping screw with a stub at the end of the threaded section opposite the connecting element can press against an upward-facing edge of one of the two clamping jaws. In this case, screwing the clamping screws into the internal thread of the bore in the main body from above exerts pressure on each of the clamping jaws, for example, pressing them together into the clamping position.Moving the clamping jaws away from each other into the release position can be achieved, for example, by unscrewing the clamping screws upwards from the main body and by means of elastic springs which push the clamping jaws apart.

[0014] In practice, the clamping jaws can be pivotally attached to the main body. By pivoting the clamping jaws around pivot axes, it is possible to move the opposing sides of the clamping jaws away from each other or towards each other, and to adjust the release or clamping position. To For this purpose, both clamping jaws or only one of the two clamping jaws can be pivotally arranged. In particular, the clamping jaws can have separate pivot axes. The clamping element can then engage the clamping jaws, especially in an area located between the pivot axes.

[0015] In one practical embodiment, the main body can have a recess in which the clamping jaws are arranged. The recess is formed in a lower surface of the main body, opposite the upper surface, and is perpendicular to the upper surface. In particular, the recess can be a slot, i.e., a narrow, elongated recess in a plane, in which the clamping jaws are at least partially arranged. By inserting the pivotable clamping jaws into a slot in the main body, the clamping jaws are guided along the main body, reducing the risk of a user of the device pinching their fingers. The main body can additionally have a second slot that is perpendicular to the first slot and perpendicular to the upper surface. A gap is formed between the clamping jaws in a clamping plane, in which the flat support element can be clamped.The clamping plane can coincide with the plane of the second slot, so that the second slot guides the support element into its intended position between the clamping jaws. The main body can then be placed onto the upper edge of the support element using the second slot and clamped to the support element by the clamping jaws located in the first slot.

[0016] In practice, the clamping jaws can have a sawtooth profile on their facing sides. This sawtooth profile makes attaching the mounting device to the support element particularly secure because the saw teeth of the profile exert high surface pressure against the support element in the clamping position.

[0017] In practice, the holding element can be attached to the top of the main body in a sliding direction perpendicular to the top surface. This sliding attachment of the holding element allows workpieces of varying thicknesses to be fixed between the top of the main body and the holding element.

[0018] Implementing a sliding mounting of the holding element is particularly simple in practice when the holding element is attached to the main body by means of an elastic clamping device, such as a tension spring or bending spring. This device pulls the holding element towards the top of the main body, where the main body has an inclined guide surface opposite the underside of the holding element. This guide surface defines an insertion slot that runs obliquely to the direction of movement. A workpiece to be machined, such as a metal plate, wooden board, or plastic sheet, can be inserted obliquely into this insertion slot. As the workpiece pivots downwards into a plane perpendicular to the direction of movement, it lifts the holding element relative to the main body, thus widening the slot. The elastic clamping device counteracts this lifting action and thus secures the workpiece to the mounting device.

[0019] In another practical embodiment, the clamping jaws can each have a projection on their opposite sides. These projections act as levers, allowing the clamping jaws to be pivoted from the clamping position to the release position. Manually actuating the levers after releasing the clamping device moves the clamping jaws from the clamping position to the release position, enabling the main body to be removed from the support element.

[0020] In practice, clamping jaws pivotally mounted on the main body can be supported by plain bearings, particularly solid friction plain bearings. These plain bearings ensure smooth pivoting between the release and clamping positions. Additionally, plain bearings are durable and easy to clean.

[0021] Additionally or alternatively, the clamping jaws can be made of a material with higher strength than the main body. This reduces wear on the mechanically stressed clamping jaws and increases their service life.

[0022] Another aspect of the invention relates to a method for processing a flat workpiece on a waterjet cutting system with a worktable comprising a plurality of flat, upright support elements as described above, arranged at intervals from one another, wherein the workpiece is placed on a plurality of spacer elements distributed over the surface of the workpiece. Each of the spacer elements comprises a lower slotted area, into the slot of which a support element is inserted, and a second unslotted area, on the free end surface of which the workpiece rests.

[0023] Furthermore, the proposal described here concerns the spacer element described above, as well as a set for fixing a workpiece to a workbench with a plurality of flat, upright support elements, comprising at least one fastening device as described above and a plurality of spacer elements, i.e., two or more spacer elements. If the spacer element has a small, approximately point-shaped upper end face for supporting the underside of the workpiece, at least three spacer elements should be used. Three points define an area. If the upper end face of at least one spacer element extends over a greater length, two spacer elements may suffice. However, with such long spacer elements, there is a risk that they will be destroyed by the water jet, whereas point-shaped spacer elements can be positioned in such a way that few or no spacer elements are cut by the water jet.

[0024] Spacers are used to create a gap between the underside of the workpiece and the support element. When cutting a workpiece with a water jet, the water, when the jet passes over a support element, rebounds from the upper edge of the support element and can strike the underside of the workpiece. With delicate workpieces, such as decorative wood or acrylic glass, there is a risk that their underside will be damaged by water rebounding from the support elements. By placing the spacers on the support elements and creating the resulting gap between the underside of the workpiece and the upper edges of the support elements, it is ensured that the kinetic energy of the rebounding water upon impact with the underside is sufficiently low to prevent damage.By fixing the workpiece with the clamping device, it is held securely, and the workpiece resting on the spacers provides even support. The combination of the clamping device and the spacers ensures that the workpiece maintains its predetermined position above the worktable during machining, allowing for precise processing and preventing damage to the underside from splashing water.

[0025] In practice, the length of the unslotted areas of all spacer elements can be the same. This allows a plurality of spacer elements to create a plane above the plane of the edges of the support elements, on which a workpiece can be placed with a flat side. In particular, the length of the unslotted areas of all spacer elements can also be identical to the distance between the top of the fastening device and the edge of the support element to which the fastening device is attached.

[0026] In practice, the spacer elements can be tubular. A slot can then be machined into a lower end face of the tube at a right angle to the end face. The end face opposite this slotted end face is the free end face of the unslotted area. The workpiece is placed on this free end face. Tubular spacer elements are compact and offer the advantage of being able to be positioned very flexibly on the wear plates. With a known cutting pattern of the workpiece to be machined, it is therefore possible to position the spacer elements in such a way that a water jet processing the workpiece passes by the spacer elements. This prevents damage to the spacer elements.

[0027] In this context, it is also worth noting the possibility of visualizing the cutting path before processing a flat workpiece on a waterjet cutting system by optically projecting the processing pattern, particularly a cutting pattern to be produced. The processing pattern can be projected onto the worktable or the workpiece resting on it using a light beam, especially a laser beam. Based on the projected cutting pattern, it is possible to predict which areas will not be cut by the waterjet. The workpiece to be processed can then be aligned with the cutting pattern, for example, when processing a wooden workpiece and the grain direction needs to be matched to the cutting path.The fastening device and / or the spacer elements on which the workpiece rests can be arranged and positioned relative to the machining image in such a way that they do not lie on a cutting line and are not damaged by the water jet.

[0028] As an alternative to a tubular design, the spacer elements can be designed in a strip-like form. These strip-like spacer elements have a slotted lower section, allowing them to be positioned over a significant portion or the entire length of a straight support element (also called a wear plate). By using strip-shaped spacer elements, a workpiece can be securely supported with just two spacer elements. Fewer spacer elements need to be placed on the wear plates, making the process particularly fast.

[0029] In practice, the spacers can be made of plastic. Plastic is particularly inexpensive and easy to work with. At the same time, the strength of most plastics is high enough to bear the load of a workpiece. However, wooden tubes, e.g., made of bamboo, can also be used.

[0030] In practice, when processing a workpiece on a waterjet cutting system, the workpiece can be fixed with at least one clamping device as described above, whereby the clamping device is clamped onto a support element. This ensures that the workpiece is securely held and can be processed precisely. Brief description of the drawings

[0031] Further practical embodiments and advantages of the invention are described below in connection with the drawings. Fig. 1shows a perspective view of a fastening device according to a first embodiment from a low angle. Fig. 2 shows a perspective view of the fastening device made of Fig. 1 from a slightly elevated angle. Fig. 3 shows a cutaway side view of the fastening device Fig. 1 . Fig. 4 shows a cutaway front view of the mounting device Fig. 1 . Fig. 5 shows a perspective view of a fastening device according to a second embodiment from an oblique angle above. Fig. 6 shows a cutaway front view of the mounting device Fig. 5 . Fig. 7 shows a perspective view of a spacer element that is attached to the fastening device made of Fig. 1 can work together in one sentence. Fig. 8 shows a perspective view of another distance element. Fig. 9 shows a perspective view of another distance element. Fig. 10shows a perspective view of another distance element. Fig. 11 shows a perspective view of another distance element. Fig. 12 shows a perspective view of another distance element. Fig. 13 shows a first perspective view of a wear plate with spacer element according to Fig. 7 and fastening device according to Fig. 1 . Fig. 14 shows a first perspective view of a wear plate with spacer element according to Fig. 7 and another embodiment of a fastening device. Fig. 15 shows a detached perspective view of the fastening devices made of Fig. 14 . Fig. 16 shows a sectional view of the fastening devices and the spacer element made of Fig. 14 when attaching a workpiece. Fig. 17 shows one of the Fig. 16 corresponding illustration with the workpiece swivelled into the machining position. Fig. 18shows a top view of a workbench for machining a workpiece with spacers and fastening devices. Fig. 19 shows a perspective oblique top view of the arrangement. Fig. 18 . Description of the embodiments

[0032] The Figures 1 to 4 show a first embodiment of the fastening device in various views. Figures 5 and 6 shows a second embodiment of the fastening device. Figures 7 to 12 show spacer elements, preferably in combination with the fastening device made of Figs. 1 to 4 can be used. Figures 13 to 18 The drawings explain the interaction of the fastening devices and the spacers. Identical or functionally equivalent elements are designated with the same reference numerals.

[0033] With the in the Figures 1 to 4The fastening device 1 shown allows a workpiece 2 to be fixed to a flat, upright support element 3 of a workbench, as is the case, for example, in Figure 13 The support element 3 is a flat sheet of metal or plastic with a flat upper edge, onto which the workpiece 2 is often placed directly in known prior art machining processes. Such support elements 3 are referred to as wear plates in waterjet cutting. The wear plates 3 are generally located in a water basin or collection basin, which forms the worktable of a waterjet cutting system. As an alternative to multiple parallel wear plates 3, it is also known to use intersecting support elements forming a grid.

[0034] The fastening device 1 has a main body 4 to which two clamping jaws 5a, 5b are movably attached relative to each other. The movable attachment of the clamping jaws 5a, 5b is achieved by means of sliding bearings 6a, 6b attached to the main body 4, in which the clamping jaws 5a, 5b are each slidably pivoted about a pivot axis. By pivoting the clamping jaws 5a, 5b, they can be moved towards each other into a clamping position and away from each other into a release position. A gap 7 is formed between the clamping jaws 5a, 5b in a first plane. When the opposing sides of the clamping jaws 5a, 5b are oriented substantially parallel to each other, the thickness of the gap 7 between them corresponds approximately to the thickness of the support element 3.

[0035] The clamping jaws 5a, 5b project partially below the main body 4 and thus extend at least partially beneath it. However, a larger section of the clamping jaws 5a, 5b is arranged in a recess 8 in the main body 4. The recess is formed in the shape of a first slot 8. The first slot 8 defines the plane in which the clamping jaws 5a, 5b are pivotable. The width of the first slot 8 corresponds approximately to the thickness of the clamping jaws 5a, 5b perpendicular to their direction of movement. The clamping jaws 5a, 5b and the sliding bearings 6a, 6b in which the clamping jaws 5a, 5b are mounted are protected from contamination by their arrangement within the slot 8. Furthermore, this arrangement reduces the risk of a user pinching their fingers with the clamping jaws 5a, 5b.

[0036] In Figure 4The representation of the clamping jaws 5a, 5b is divided along the central plane of the gap 7, indicated by a dashed line. The left clamping jaw 5a is shown in the release position and the right clamping jaw 5b in the clamping position. A second slot 9 is formed in the main body 4 at right angles to the first slot 8. The second slot 9 is located in the same plane as the gap 7 between the clamping jaws 5a, 5b. The width of the second slot 9 is chosen such that the support elements 3 can be inserted into the second slot 9 without obstruction.

[0037] The clamping jaws 5a, 5b are moved by means of a clamping element, designed as a clamping screw 11, accessible from the top 10 of the main body 4. The clamping screw 11 extends through a bore 12 with an internal thread in the main body 4, which extends from the top 10 of the main body 4 to the first slot 8. The clamping screw 11 has a threaded section with an external thread, allowing it to be screwed into or out of the bore 12 relative to the top 10. The upper end of the clamping screw 11 is designed as a setscrew and can be fully screwed into the bore 12 in the main body 4. The upper end of the clamping screw 11 has a connecting element 13, with which a screwdriving tool can be positively coupled. At its lower end, the clamping screw 11 has a driver 14. The driver 14 projects from the bore 12 and into the first slot 8.The driver 14 engages a recess in the facing sides of the clamping jaws 5a, 5b, which is complementary to the driver 14. By screwing the clamping screw 11 into the main body 4 from the top 10, pressure is exerted on the clamping jaws 5a, 5b via the driver 14 and the recess, thereby pressing the clamping jaws 5a, 5b into the release position. As mentioned, the left half of the... Fig. 4 The clamping jaw 5a and the left half of the clamping screw 11 are in this release position. Unscrewing the clamping screw 11 upwards causes both clamping jaws 5a and 5b to pivot towards each other into the clamping position. The right clamping jaw 5b and the right half of the clamping screw 11 are in Fig. 4 shown in this clamping position.

[0038] It should be noted that the clamping device can also be implemented using any other element. For example, instead of a clamping screw, a so-called quick-release device, known from bicycle manufacturing, can be used. In this device, a clamping lever with an eccentric rests on the upper surface 10 of the main body 4, whereby rotating the eccentric pulls a shaft with a drive element upwards and moves the clamping jaws into the clamping position.

[0039] On their opposing sides, the clamping jaws 5a, 5b each have a sawtooth profile 15. Due to the sawtooth profile 15, the clamping jaws 5a, 5b have point-like contact areas with the surfaces of the support element 3 in the clamping position, resulting in a particularly high surface pressure in the contact areas and ensuring secure attachment of the fastening device 1 to the support element 3.

[0040] In particular, when the clamping jaws 5a, 5b press into the material of the support element 3 with their sawtooth profiles 15, a high force may be required to release the clamping jaws 5a, 5b from the support element 3. To prevent damage to the clamping screw 11, for example, when releasing the clamping jaws 5a, 5b, the clamping jaws 5a, 5b can have structures by which an additional force can be manually applied to open them. These structures are designed as projections 16a, 16b on the opposite sides of the clamping jaws 5a, 5b. When the projections 16a, 16b are pressed together (i.e., moved towards each other), the clamping jaws 5a, 5b are pivoted about their respective pivot axes into the release position. By simultaneously pressing the projections together and screwing in the clamping screw 11, the clamping jaws 5a, 5b can be easily detached from the support element 3.

[0041] To fix the workpiece 2 to the fastening device 1 of the Fig. 1 - 4 A retaining element 17 is arranged above the main body 4. In this embodiment, the retaining element 17 is flat and has the shape of an annular disc. The retaining element 17 is slidably attached to the top surface 10 of the main body 4 by means of a clamping device 18, which in the embodiment described here is a clamping screw 18 screwed into a threaded hole 23 of the main body 4, in a displacement direction perpendicular to the top surface 10 of the main body 4. This creates a second gap 19 in a second plane extending perpendicular to the first plane between the retaining element 17 and the top surface 10 of the main body 4. The workpiece 2 can be clamped in the second plane between the top surface 10 and the retaining element 17.

[0042] The Fig. 13As mentioned, this shows a fastening device 1 clamped onto a wear plate 3. Figs. 1 to 4 , which fixes a workpiece 2. The wear plate 3 protrudes through the slot 9 and is clamped by the clamping jaws. The workpiece 2 is a flat plate which is clamped against the main body 4 of the fastening device 1 by the disc-shaped holding element 17.

[0043] Furthermore, in Fig. 13 A spacer element 20 can be identified, the free end surface of which supports the plate-shaped workpiece 2. Embodiments of such spacer elements 20 are described further below with reference to the Figs. 7 - 11 explained in more detail.

[0044] In the Figures 5 and 6A second embodiment of the fastening device 1' is shown. With the exception of the features described below, the second embodiment of the fastening device 1' corresponds to the first embodiment described above. In the second embodiment of the fastening device 1', the retaining element 17' is larger than the top surface 10' of the main body 4' and is essentially rectangular. It projects laterally beyond the main body, so that a workpiece 2' can be pressed by the retaining element 17' against the upwardly facing edge of the support element 3', to which the fastening device 1' is fixed. The retaining element 17' is slidably attached to the top surface 10' of the main body 4' by two identical clamping screws 18' in a direction of movement perpendicular to the top surface 10' of the main body 4'. The clamping screws 18' are identical to the clamping screw 18 of the first embodiment.

[0045] The clamping jaws 5a', 5b' are each mounted so as to be pivotable about a pivot axis.

[0046] The clamping jaws 5a', 5b' are moved separately by means of a clamping element designed as a clamping screw 11', accessible from the top 10' of the main body 4'. The two clamping screws 11' each protrude through a bore 12' with an internal thread in the main body 4', extending from the top 10' of the main body 4' to the first slot 8'. The clamping screws 11' are essentially designed like the clamping screw 11, except that they do not have a driver, but rather a stub at their lower end. The two stubs of the two clamping screws 11' protrude from the two bores 12' and into the first slot 8'. Each of the two stubs presses against an upward-facing edge of one of the two clamping jaws 5a', 5b'. By screwing the clamping screws 11' into the main body 4' from the top 10', pressure is exerted on the clamping jaws 5a', 5b' via the stub, which causes the clamping jaws 5a', 5b' to clamp into the Fig. 6The clamping position shown is pressed. Unscrewing the clamping screws 11' upwards means that no pressure is exerted on the clamping jaw 5a' or 5b' located below the unscrewed clamping screw 11'. Coil springs (not shown here), one of which is arranged around the pivot axis of the clamping jaws 5a', 5b' and connected to one of the two clamping jaws 5a', 5b', push the clamping jaws apart when the pressure on the clamping jaws 5a', 5b' is removed by unscrewing the clamping screws 11'.

[0047] Fig. 7Figure 20 shows a spacer element 20, which is designed as a round tube section with parallel end faces 21a, 21b. A diametrically opposed slot 22 is formed in the spacer element 20 at right angles to the lower end face 21b, the width of which is matched to the thickness of the support element 3. The spacer element 20 is slid onto the support element 3 with the slot 22. Consequently, the width of the slot 22 should be slightly less than the thickness of the support element 3 so that the slot 22 expands elastically when slid onto the support element and the spacer element 20 sits firmly on the support element 3. The upper end face 21a forms the free end face of the spacer element 20, on which the workpiece 2 can rest. An unslotted area of ​​the spacer element 20 extends in the axial direction of the spacer element 20 from the free end face 21a to the slot 22. As shown in Figure 20, the spacer element 20 is slid onto the support element 3. Fig. 13It can be seen that the length of the unslotted area of ​​the spacer element 20 is identical to the distance between the upper edge of the support element 3 and the top surface 10 of the main body 4 of the mounting device 1, to which the mounting device 1 is attached. The upper edges of the support elements 3 of a waterjet cutting system generally lie in the same plane. Thus, a common plane can be defined by the top surface 10 of the mounting device 1 and the free end surface 21a of the spacer element 20, which forms the support plane for the flat underside of the workpiece 2.

[0048] In practice, several spacer elements 20 and / or fastening devices 1 can also span a common plane, as in the Figures 18 and 19as shown. In this case, the length of the unslotted areas of all spacer elements 20 is identical and corresponds to the distance between the top 10 of all fastening devices 1 and the bottom of the workpiece 2.

[0049] The distance between adjacent spacer elements 20 must be selected such that the workpiece 2 does not deflect excessively between these spacer elements 20. The distribution of the spacer elements 20 over the surface of the workpiece can be, as shown in Fig. 18 depicted, be irregular. In Fig. 18 and 19A plate-shaped workpiece 2 with a square surface is attached at all four corners by means of a fastening device 1. The number of fastening devices 1 can also be reduced or increased to securely fix the workpiece 2. When processing with water jets impacting the surface of the workpiece 2 perpendicularly, hardly any transverse forces act on the workpiece 2, and the required holding force of the fastening devices 1 is quite low, so that fewer than four fastening devices 1 may suffice.

[0050] The spacer elements 20 can also be distributed irregularly over the surface of the workpiece 2. It is possible to project the cutting pattern to be generated by the water jet onto the worktable using a projection device, particularly a laser. With a workpiece made of natural material, such as a wooden or stone slab, grain patterns and color patterns can be aligned with the cutting direction to be produced. It is also possible to distribute at least the majority of the spacer elements 20 over the surface of the workpiece 2 in such a way that they are not cut by the water jet. In this way, at least the majority of the spacer elements 20 can be reused multiple times.

[0051] The in the Figure 7 , 13 , 14 and 16The spacer elements 20 shown have the shape of a tube with a circular cross-section. However, the shapes of the spacer elements can deviate from the circular shape. For example, rectangular tubes or other tube shapes can be used whose end faces extend perpendicular to their axis of symmetry and which have a slot in a plane that preferably contains the axis of symmetry. Other shapes of the spacer elements, each mounted on a support element, are shown in the Figures 8 - 12 depicted.

[0052] The Figures 8 - 12 show strip-shaped spacer elements. The spacer element 20a of the Fig. 8The cross-section resembles the gable end of a house. In axial plan view, this cross-section consists of a rectangular base and a roof section mounted on it, with roof surfaces arranged symmetrically to the center line of the rectangle. The slot 22 is located in the center of the lower base line of the rectangular base and extends upwards along the vertical axis of symmetry of the cross-section to approximately the midpoint of the height of the spacer element. The ridge line of the roof section of the strip-shaped spacer element 20a forms the free end surface or face 21a, upon which the workpiece rests.

[0053] The distance element 20b of the Fig. 9It has a circular cross-section, with the slot 22 extending radially to the center of the cross-section. The lateral surface of the strip-shaped spacer element 20a opposite the opening of the slot 22 forms the free end face 21a on which the workpiece rests. A similar situation applies to the spacer element 20c of the Fig. 10 , which does not have a solid cross-section, but rather a cylindrical shell with radial webs, manufactured as an extruded profile.

[0054] The Fig. 11 shows another strip as a spacer element 20d with the same profile as strip 20a in Fig. 8 Longitudinally running cavities are incorporated here, saving material and weight. Spacer element 20d is manufactured as an extruded profile. Spacer element 20e is also manufactured as such. Fig. 12 is an extruded profile. The profile cross-section essentially corresponds to that of the spacer element 20d. Fig. 11, wherein the free end face 21a is enlarged by a horizontally extending web.

[0055] As mentioned above, the Fig. 13 a combination of the fastening device from the Fig. 1 with a spacer element 20 from the Fig. 7 . Similarly, the fastening device can be combined with the other spacer elements 20a - 20e.

[0056] During a session in the Figs. 14 to 17In the illustrated embodiment of the fastening device 1, the main body 4, the clamping jaws 5a, 5b, and the clamping screw 11 are essentially designed as described above. Only the top surface 10 of the main body and the retaining element 17 are designed differently. The top surface 10 of the main body 4 has a guide surface 24 that is angled relative to the horizontal underside of the retaining element 17, and the retaining element 17 is designed as a spring clamp. The spring clamp 17 presses the workpiece 2 toward the top surface 10 when it is pivoted into the horizontal position, as shown in the figure. Fig. 10 shown. The spring clamp 17 thus also forms the clamping element. In this embodiment, the screw 18 only fixes the spring clamp 17 to the main body 4.

[0057] The upper surface 10 of the main body 4 extends from its right edge, facing the viewer, towards its center. The inclined guide surface 24 adjoins the horizontal upper surface 10. It is inclined towards the underside of the fastening device 1, so that the workpiece 2 can be inserted laterally into the gap between the inclined guide surface 24 and the spring clamp 17, as shown in Fig. 10As shown, when the workpiece 2 is swung down into a horizontal position, it pushes the spring clamp 17 upwards from below. This causes the spring clamp 17 to deform elastically. The workpiece 2 is thus held securely and is easy to use. Like the holding elements 17 of the previously described embodiment, the spring clamp 17 has an opening 25 so that a user of the fastening device 1 can engage a screwdriver with the connecting element 13 of the clamping screw 11 under the spring clamp 17.

[0058] It should be noted that the shape of the holding element and the clamping device can be varied and adapted to the respective machining process and the shape of the workpiece.

[0059] The features of the invention disclosed in this description, in the drawings, and in the claims can be essential for realizing the invention in its various embodiments, both individually and in any combination. The invention is not limited to the described embodiments. It can be varied within the scope of the claims, taking into account the knowledge of the person skilled in the art. List of reference symbols

[0060] 1 Fastening device 2 Workpiece 3 Support element, wear plate 4 Main body 5a, 5b Clamping jaws 6a, 6b Slide bearing 7 First-level slot 8 Recess, first slot 9 Second slot 10 Top side 11 Clamping element, clamping screw 12 Bore 13 Connecting element 14 Driver 15 Sawtooth profile 16 Projections 17 Retaining element 18 Clamping element, clamping screw 19 Second-level slot 20 Spacer element 21a, 21b End faces 22 Slot 23 Threaded hole 24 Guide surface

Claims

1. A fastening device (1) for fixing a workpiece (2) to a flat, upright support element (3), having a main body (4), two clamping jaws (5a, 5b) movable with respect to one another attached to the main body (4), the two clamping jaws (5a, 5b) extending below the main body (4) and being movable towards one another using a clamping means (11) accessible from the top (10) of the main body (4), comprising a holding element (17) arranged above the main body (4) and movable towards the main body (4) using a clamping means (18), wherein the holding element (17) is configured to press the workpiece (2), which is arranged at least partially below the holding element (17), against the main body (4) or against the support element (3) .

2. The fastening device (1) according to claim 1, characterised in that a gap (7) is formed between the clamping jaws (5a, 5b) in a first plane and a gap (19) is formed between the holding element (17) and the top (10) of the main body (4) in a second plane, wherein the second plane is at right angles to the first plane.

3. The fastening device according to claim 1 or 2, characterised in that the clamping means (11) is a clamping screw (11).

4. The fastening device according to one of the preceding claims, characterised in that the clamping jaws (5a, 5b) are pivotably attached to the main body (4).

5. The fastening device according to one of the preceding claims, characterised in that the main body (4) has a recess (8) in which the clamping jaws (5a, 5b) are arranged.

6. The fastening device according to one of the preceding claims, characterised in that the clamping jaws (5a, 5b) have a sawtooth profile (15) on their sides facing each other.

7. The fastening device according to one of the preceding claims, characterised in that the holding element (17) is fastened to the top (10) of the main body (4) in a manner discplaceable in a displacement direction perpendicular to the top (10).

8. The fastening device according to claim 5, characterised in that the holding element (17) is fastened to the main body (4) using an elastic tensioning means which presses the holding element (17) towards the top (10) of the main body (4), wherein the main body (4) has an inclined guide surface opposite the underside of the holding element (17), which defines an insertion gap with the underside of the holding element that extends at an angle to the displacement direction.

9. The fastening device according to one of the preceding claims, characterised in that the clamping jaws (5a, 5b) each have a projection (16a, 16b) on the sides facing away from each other.

10. A set for fixing a workpiece (2) to a workbench with a flat, upright support element (3), comprising at least one fastening device (1) according to one of claims 1 to 9 and a plurality of spacer elements (20) with a slotted and an unslotted region.