Device for producing an undefined finish on a surface of a metal workpiece in a continuous process

Description

[0001] The present invention relates to a device for producing an undefined finish on a surface of a metal workpiece in a continuous process according to the preamble of claim 1.

[0002] An undefined finish is an irregular surface texture that lacks any discernible orientation in a specific direction. This type of irregular finish is also referred to as a jumbled finish, directionless grinding pattern, vibratory grinding, matt vibrated surface, or eccentric grinding pattern. The advantage of this type of undefined finish is that workpieces treated in this way can be mounted in any orientation with other workpieces to form a large overall surface, without having to pay attention to the respective orientation. This is particularly advantageous for a building facade, as the individual facade sheets can be attached to the building regardless of their processing direction.

[0003] The present invention is based on the finding that when the workpiece enters the area of the disc grinder, a particularly large force acts on the edge area of the workpiece, with the result that a greater grinding effect is achieved in this edge area than in the remaining part of the workpiece, so that a uniform grinding pattern is not produced.

[0004] In known devices for producing an undefined finish, the contact pressure is therefore reduced so much that a uniform, undefined finish is produced. The disadvantage here is that the grinding performance is low, which leads to long processing times, or that several disc grinders are used in parallel, as for example in the device known from EP 1 500 467 A1, which is discussed in more detail below: EP 1 500 467 A1 discloses a device for producing an undefined finish on the surface of a stainless steel sheet using a through-feed process, which device comprises a conveyor belt for transporting the workpiece under the grinding unit, a tool bridge for holding the grinding unit, and a total of two grinding units, each with two disc grinding units.Each of the grinding units rotates around a vertical axis V, V', the disc grinding units rotate around their own vertical axis Z, and the actual grinding discs are mounted eccentrically and rotate around the N axis. The eccentric stroke, i.e., the distance between the N and Z axes, is 3 mm. Furthermore, the tool bridge oscillates in the direction of the X axis, so that the surface structure created by the sandpaper is very diffuse and undefined, resulting in an undefined finish on the surface of the stainless steel plate.

[0005] The two grinding units, arranged side by side and rotating about their respective axes V, V', are positioned so closely together that the areas covered by the grinding discs overlap, creating a uniform grinding pattern even in the center of the workpieces. The grinding units rotate about their axes V and V' with such a time offset that at a given time, one grinding unit is aligned in the direction of transport, while simultaneously the other grinding unit is aligned transversely to the transport device, thus achieving an overlap of the ground surface with the respective grinding units. However, coordinating such overlapping movements is very complex, and in the event of a defect, there is a risk of damage to the entire device.

[0006] Furthermore, the manufacture and maintenance of a device according to EP 1 500 467 A1 is very complex because the actual disc grinding unit rotates around a large number of axes and also oscillates in the X-direction.

[0007] Further related devices are disclosed in US 6 244 933 B1, US 6 602 118 B1, US 2006 / 019579 A1 and US 5 927 264 A.

[0008] In order to reduce the manufacturing and operating costs of a device of the type mentioned above, the aim of the present invention is to create a device of the type mentioned above which does not require overlapping working areas of the grinding units and yet still produces a high grinding performance.

[0009] Based on this, the object of the present invention is to create a device of the type mentioned at the outset which, despite different contact pressures on the edge and inside the workpiece, produces a uniform grinding pattern with an undefined finish.

[0010] As a technical solution to this problem, the invention proposes a device of the type mentioned above with the features of claim 1. Advantageous further developments of this device can be found in the respective subclaims.

[0011] A device designed according to the technical teaching according to claim 1 dispenses with two independently operating grinding units and manages with the same grinding performance with a single disc grinding unit if the grinding unit hangs in a holding device so that it can be displaced vertically upwards that the grinding unit moves upwards when the workpiece acts on the grinding disc.

[0012] The displacement device can comprise a base plate attached to a tool bridge, to which two vertically aligned guide rails are attached. These guide rails are positively engaged by a holding plate mounted on the grinding unit. The holding plate, held by the guide rails, can be moved vertically relative to the base plate.

[0013] During processing, the grinding unit rests on the workpiece with the grinding disc, pressing the abrasive against the workpiece with its own weight. This has the advantage that when the workpiece hits the grinding disc, the grinding unit is pushed upwards, thus preventing excessive contact pressure from the abrasive at the edge of the workpiece.

[0014] Even in the event of an unexpected increase in grinding pressure, for example due to bending of the workpiece or a thickness tolerance of the workpiece, the grinding unit can move upwards and thus avoid an increase in contact pressure and thus a change in the grinding pattern.

[0015] According to the invention, the contact pressure is determined by the weight of the sanding unit, which remains the same regardless of where the workpiece is located on the sanding disc, or regardless of the workpiece's irregularity. Thus, the quasi-proximal sanding unit avoids the high contact pressure typical of prior art, particularly when the workpiece enters the disc sander, resulting in a uniform, undefined finish.

[0016] A further advantage is that by avoiding the increased contact pressure, vibrations and oscillations of the entire device are at least partially avoided, which reduces the load on the device and increases its service life.

[0017] According to the invention, a brake, in particular a friction brake, is provided on the eccentrically held disc sanding unit to slow down the sanding disc. The moment the disc sanding unit does not engage the workpiece or does not engage sufficiently, the sanding disc rotates about the vertical axis N of the sanding disc and gradually reaches high speeds. When the disc sanding unit is then fed back to the workpiece, the sanding disc impacts the workpiece with its high kinetic energy and grinds the surface accordingly. Due to the friction between the workpiece and the sanding disc, the sanding disc increasingly slows down and then, at the appropriate time, stops rotating about the axis N. During this phase, however, an undesirable sanding pattern is created on the surface of the metal workpiece, which then has to be laboriously sanded over again.To prevent such unwanted acceleration of the grinding disc, a brake, in particular a friction brake, is provided. The brake is applied to the grinding disc and, due to the existing friction, prevents unwanted rotation of the grinding disc around the N axis.

[0018] According to the invention, the brake is designed as a corrugated hose and comprises, on the side adjacent to the grinding disc, a friction ring preferably made of abrasion-resistant plastic, in particular Kevlar, PE, or POM. The invention provides for the integration of a spring steel coil into the corrugated hose, which presses the friction ring onto the grinding disc and thus enhances the braking effect.

[0019] In a preferred embodiment, an air pressure cylinder is provided between the holding device and the grinding unit, which partially raises the grinding unit. This has the advantage of reducing the weight of the grinding unit acting on the grinding wheel and thus the contact pressure acting on the workpiece, thus achieving the desired grinding pattern. In a preferred development, the air pressure cylinder is adjustable to allow the weight and thus the contact pressure to be easily adjusted.

[0020] In another preferred embodiment, means for supporting weights are provided on the grinding unit. These weights can be used to increase the total weight of the grinding unit to increase the contact pressure, if necessary.

[0021] In another preferred embodiment, a bevel is formed on the edge of the grinding disc, so that the workpiece is guided under the disc grinder by means of the bevel.

[0022] In a further preferred embodiment, a stopper is provided on the holding device, against which the grinding unit rests. The stopper is vertically displaceable and can be locked in the desired position on the holding device. This stopper prevents the grinding unit, which is held vertically displaceably in the holding device, from moving vertically downward in an uncontrolled manner. It is positioned on the holding device in such a way that the grinding plate of the grinding unit is positioned at the desired height above the transport device, as required for processing the workpiece.

[0023] In a preferred embodiment, the tool bridge has means for moving the grinding unit across the entire workpiece width transversely to the transport direction. This has the advantage that the at least one disc grinding unit mounted on the tool bridge can be moved transversely to the transport direction and across the entire workpiece width, so that the workpiece can be machined across its entire width and provided with an undefined finish with a single disc grinding unit.

[0024] A particular advantage of the device according to the invention, particularly with a feed rate of 0.5 mm to 2 mm, is that the flexible and yielding nonwoven fiber grinding wheel gives way slightly when gripping the workpiece, thus evenly processing the surface of the workpiece to produce an undefined finish. Depending on the workpiece and the desired surface quality, a correspondingly thick nonwoven fiber grinding wheel can be used. In particular, a nonwoven fiber grinding wheel that is appropriately thick for the application allows the contact pressure to be adjusted as required, because the thicker the nonwoven fiber grinding wheel, the lower the grinding pressure acting on the workpiece. It has proven advantageous to select a nonwoven fiber grinding wheel with a thickness of at least 5 mm, but preferably with a thickness of 6 mm.Even an undefined finish can be achieved on a metal workpiece using a 15 mm thick nonwoven sanding disc.

[0025] A further advantage of the device according to the invention is that less energy is required to grind the metal workpiece.

[0026] In a preferred embodiment, the eccentric sanding unit has an eccentric stroke of at least 6 mm, preferably 9 mm. This extremely large eccentric stroke, combined with the uniform feed of the workpiece by the conveyor belt and the transverse movement of the eccentric sanding unit along the tool bridge, has the advantage that the grinding wheel is reached irregularly in the longitudinal direction, the transverse direction, and in all other intermediate directions of the conveyor device, resulting in a very uniform, undefined finish on the surface of the metal workpieces.

[0027] In yet another preferred embodiment, at least one vertically aligned elongated hole is provided in the upper region of the corrugated hose, so that the corrugated hose, particularly if it is provided with a spring steel coil, can be pre-tensioned to achieve the desired braking effect on the sanding disc. The corrugated hose is attached to the disc sanding unit by a screw passing through the elongated hole, with the position of the corrugated hose being adjustable along the elongated hole to adjust the pre-pressure of the brake on the sanding disc. It is understood that multiple elongated holes can also be provided distributed around the circumference of the corrugated hose.

[0028] In another preferred embodiment, an eccentrically shaped shim is provided on the disc sanding unit to compensate for the imbalance caused by the eccentric mounting of the sanding disc. In an advantageous further development, this shim has an oval or round outer contour, with the thickest part of the shim being positioned directly opposite the eccentrically arranged sanding disc.

[0029] In another, likewise preferred embodiment, the grinding disc has a diameter of preferably 250 mm and is operated at a speed of preferably 1,500 rpm (revolutions per minute). With this comparatively large grinding disc, a correspondingly large surface can be machined. If the disc grinding unit is then operated at a comparatively low speed of 1,500 rpm, this has the advantage that a relatively large eccentric stroke of preferably 9 mm can be realized, and that with this large eccentric stroke, a cutting speed sufficient for economical machining of the workpieces is achieved.A further advantage is that this large eccentric stroke enables movements of the abrasive grain in a comparatively large radius, with the result that a large-area machining of the workpiece is achieved and that a very good and evenly distributed, undefined finish is produced over the surface.

[0030] In an advantageous embodiment, the grinding wheel is designed as a nonwoven fiber grinding wheel. This nonwoven fiber grinding wheel is flexible and compliant and, in conjunction with the eccentric disc sanding unit, produces a high-quality, undefined finish on the surface of a metal workpiece, especially on stainless steel workpieces. This nonwoven fiber grinding wheel is made of a synthetic resin, nylon fiber, and abrasive mineral, with aluminum oxide and / or silicon carbide being used as the abrasive mineral. Nonwoven fiber grinding wheels are offered, for example, by 3M under the brand name Scotch-Brite.

[0031] The great advantage of the grinding wheel according to the invention, in particular the nonwoven fiber grinding wheel, is that the elastically deformable layer, in particular the individual fibers and the synthetic resin, can be compressed when a force is applied, thereby at least partially storing the energy used. At the same time, the compressed layer strives to return to its original position (memory effect) and in doing so exerts a certain force on the abrasive. This force correlates with the contact pressure of the abrasive on the workpiece. The special feature of this is that the deformable layer absorbs force peaks well and initially gives way at the moment the force peak occurs. As a result, this force peak does not lead to an increased contact pressure of the abrasive on the workpiece and thus does not lead to a changed grinding pattern.

[0032] When the workpiece hits the grinding wheel according to the invention, in particular the nonwoven fiber grinding wheel, it is compressed first at the edge and then over the entire surface according to the selected infeed depth, with the memory effect generating the contact pressure with which the abrasive is pressed onto the workpiece. This flexibility of the grinding wheel means that the contact pressure at the edge of the workpiece is not as high as with abrasives known from the prior art, thus preventing excessive machining in the edge area of the workpiece. The result is that, despite a high grinding performance, a uniform, undefined finish is created on the surface of the workpiece. Further advantages of the device according to the invention can be seen from the attached drawing and the embodiments described below.The embodiments mentioned are not intended to be exhaustive, but rather are exemplary in nature. They show: . Fig. 1 is a plan view of a first embodiment of a device according to the invention; Fig. 2 is a front view of the device according to Fig. 1 ; Fig. 3 a sectional enlarged detail of the disc grinding unit of the device according to Fig. 1 , cut along line III in Fig. 2 ; Fig. 4 a sectional plan view of a disc grinding unit of the device according to Fig. 1 , cut along line IV -IV in Fig. 2 ; Fig. 5 a sectional side view of the disc grinding unit of the device according to Fig. 1 , cut along line V -V in Fig. 4; Fig. 6 a side view of a part of a disc grinding unit of a second embodiment of a device according to the invention; Fig. 7 a detailed enlargement of the disc grinding unit according to Fig. 6 , cut along line VII in Fig. 6 ; Fig. 8 a detailed enlargement of the disc grinding unit according to Fig. 6 , cut along line VIII in Fig. 6 ; Fig. 9 is a plan view of a third embodiment of a device according to the invention; Fig. 10a is a perspective view of a fourth embodiment of a device according to the invention in a rest position; Fig. 10b is a perspective view of the device according to Fig. 10a in an upwardly displaced position (working position); Fig. 11 a sectional plan view of a part of the device according to Fig. 10a , cut along line XI - XI in Fig. 10a ; Fig. 12 a perspective view of a fifth embodiment of a device according to the invention.

[0033] In the Figures 1 to 5 A first embodiment of the device according to the invention for producing an undefined finish on the surface of a metal workpiece using a continuous process is shown. This device comprises a transport device 10 for the linear transport of a workpiece 12 with a circulating conveyor belt 14 on which the workpiece 12 rests flat and is transported in the transport direction indicated by arrow 16.

[0034] Above the transport device 10, a tool bridge 18 is provided on a holding frame 20, wherein a grinding unit 22 comprising two identical disc grinding units 24 is held on the tool bridge 18. Furthermore, means for moving the grinding unit transversely to the transport direction 16 are provided on the tool bridge 18. These means for moving the grinding unit 22 comprise a rail 26 mounted transversely to the transport direction and a toothed belt 30 driven by an electric drive 28, which moves the grinding unit 22 back and forth. Such means are known, for example, from DE 20 2012 002 267 U1.

[0035] The disc sanding unit 24 has its own electric drive 32 and an eccentrically mounted sanding disc 34, to which a sanding disk 35 is held by means of a hook-and-eyelet connection. The eccentrically arranged center axis of the sanding disc 34 is designated N and spaced 9 mm from the Z axis, resulting in an eccentric stroke of 9 mm. In another embodiment, the eccentric stroke can also be between 6 mm and 15 mm. The sanding disc 34 is held on the disc sanding unit 24 by a ball bearing 38, has a diameter of 250 mm, and is driven by the electric drive to rotate about a Z axis, with the sanding disc rotating at 1,200 to 1,800 rpm, preferably at 1,500 rpm.

[0036] A grinding wheel 35 is held on the underside of the grinding plate 34 by means of a hook-and-eye connection. This grinding wheel 35 comprises a layer 36 made of a resilient material with a memory effect, in which the abrasive 37 is embedded. In this embodiment, this layer 36 is formed from a flexible and resilient fiber fleece, wherein a resin-bonded abrasive, for example aluminum oxide and / or silicon carbide, is embedded in the fiber fleece. Such fiber fleece grinding wheels 35 are available, among others, from the company 3M under the name Scotch-Brite. When machining stainless steel workpieces 12, a fiber fleece grinding wheel 35 with a layer 36 of 6 mm thickness has proven effective. This layer can be compressed to up to 4 mm depending on the contact pressure, i.e., with a feed depth of up to 2 mm.In another embodiment, and particularly for other metal workpieces, a grinding wheel with a thickness between 5 mm and 15 mm can also be used.

[0037] As particularly in the Figures 3 to 5 As can be seen, a compensating disc 40 is provided on the disc grinding unit 24, which compensates for the imbalance caused by the eccentric attachment of the grinding disc 34.

[0038] A typical grinding process is described in detail below: The metal workpiece 12, here made of stainless steel, is placed on the conveyor belt 14 and transported by the conveyor belt 14 in the direction of arrow 16 beneath the grinding unit 22. The grinding unit 22, consisting of the two disc grinding units 24, is moved back and forth at a constant speed in the direction of the double arrow X, transverse to the transport direction 16, via the electric drive 28 and the toothed belt 30, so that the grinding disc 34 attached to the disc grinding unit 24 is moved transversely across the workpiece 12. The grinding disc 34 rotates about its central axis N and pivots about the central axis Z of the disc grinding unit 24. However, because the grinding disc 34 is held eccentrically on the disc grinding unit 24 with an eccentric stroke of 9 mm, the grinding disc 34 performs a corresponding eccentric movement with respect to the Z-axis.

[0039] A nonwoven fiber grinding wheel 35 is secured to the underside of the grinding plate 34 by means of a hook-and-loop connection (Velcro connection). This approximately 6 mm thick nonwoven fiber grinding wheel 35 is adjusted to achieve a feed depth of 1 mm. In other words, as soon as the grinding wheel 35 hits the workpiece 12, the flexible and yielding nonwoven fiber grinding wheel 35 is compressed by approximately 1 mm. This creates sufficient grinding pressure so that the surface of the stainless steel workpiece 12 is adequately ground. At the same time, the yielding and flexible nonwoven fiber grinding wheel 35 ensures that the edges of the stainless steel workpiece 12 do not become rounded, but essentially retain their original contour.

[0040] In addition, the eccentric attachment of the sanding disc 34 on the disc sanding unit 24 in conjunction with the transverse movement in the direction of the double arrow X and the feed movement of the workpiece 12 by the conveyor belt 14 results in an undefined finish on the surface of the stainless steel workpiece 12. This has the advantage that this workpiece 12 can be attached, for example, to a piece of furniture, a facade or the like, regardless of its orientation.

[0041] In the Figures 6 to 8 A disc grinding unit 124 of a second embodiment of the device according to the invention is shown. This disc grinding unit 124 has a friction brake 142 and is otherwise identical to the one shown in the Figures 1 to 5 illustrated disc grinding unit 24 of the first embodiment and can also be used in a device according to the invention.

[0042] This friction brake 142 comprises a corrugated hose 144 made of a dimensionally stable plastic material, at the lower end of which a friction ring 146 made of POM is attached. The length of the corrugated hose 144 is dimensioned such that the friction ring 146 rests on the grinding disc 134. The corrugated hose 144 is made of a dimensionally stable plastic and carries a spring steel coil 148. At its upper end, the corrugated hose 144 is attached to the disc grinding unit 124, with an elongated hole 150 provided in this area on the corrugated hose 144. The corrugated hose 144 can be adjusted via this elongated hole 150.This means that by adjusting the setting using the elongated hole 150, the corrugated hose 140, together with the spring steel coil 148, can be pre-tensioned to a greater or lesser extent, with the result that the corrugated hose 144, together with the spring steel coil 148, exerts a force on the friction ring 146 according to the pre-setting and accordingly presses on the sanding plate 134. This contact pressure on the friction ring 146 also determines the friction to be overcome between the friction ring 146 and the sanding plate 134 and thus the desired braking effect. This friction brake 142 ensures that the sanding plate 134 does not accelerate and rotates about its axis N when the disc sanding unit 124 leaves the area of the workpiece, so that when the sanding plate 134 re-engages, no undesirable sanding patterns are created on the workpiece.

[0043] Fig. 9shows a third embodiment of a device according to the invention for producing an undefined finish on a surface of a metal workpiece 212 in a continuous process, which is identical either to the one shown in the Figures 1 to 5 first embodiment shown or identical with the ones shown in Figures 6 to 8 illustrated second embodiment and additionally has a deburring unit 252. This deburring unit 252 is also attached to the tool bridge 218 and is also moved back and forth across the workpiece 212 in the direction of the double arrow X. This deburring unit 252 is arranged upstream of the grinding unit 222 and serves to deburr and round the metal workpiece 212. Such a deburring unit 252 is previously known from the prior art and is described, for example, in DE 20 2012 002 267 U1.

[0044] With a device according to this third embodiment, as in Fig. 9As described above, the workpiece, especially the stainless steel workpiece, can be deburred and rounded in a single operation, and an undefined surface finish can be created in the same operation. This results in significant cost savings because both steps are completed in one operation.

[0045] In the Fig. 10a , 10b and 11 A fourth embodiment of a device according to the invention for producing an undefined finish on a surface of a metal workpiece in a continuous process is shown in detail. Analogous to the device shown in the Figures 1 to 5In addition to the first embodiment shown, this fourth embodiment also includes a transport device (not shown here) with a conveyor belt for transporting the workpiece. The holding frame and the tool bridge of this fourth embodiment are also identical to the device shown in the first embodiment.

[0046] The grinding unit 322 of this fourth embodiment is vertically displaceable in a displacement device 354, which comprises a base plate 356 attached to the tool bridge, to which two vertically aligned guide rails 358 are attached. These guide rails 358 are positively encompassed by a holding plate 360 mounted on the grinding unit 322. The holding plate 360, held by the guide rails 358, is vertically displaceable relative to the base plate 356.

[0047] An orthogonally projecting stopper 362 is fixedly attached to the base plate 356, in which a vertically oriented spindle is held vertically movable. A rotatable and thus height-adjustable stop 366 is mounted on the spindle 364, which comes into contact with the stopper 362 as soon as the grinding unit 322 has reached its rest position. At a lower end of the spindle 364, it is firmly connected to the holding plate 360 via a fastening element.

[0048] By rotating the stop 366, the spindle 364 is moved downwards or upwards depending on the direction of rotation, and thus the holding plate 360 and the grinding unit 322 are simultaneously moved downwards or upwards. The grinding unit 322, which is guided vertically in the displacement device 154, is pressed downwards due to its own weight until the stop 366 comes to rest on the stopper 362 and remains in this position, referred to as the rest position, as can be seen from Fig. 10a can be seen. Consequently, by adjusting the stop 366, the feed depth of the grinding disc 334 can be precisely adjusted depending on the respective workpiece.

[0049] There is no upper limit, so that the grinding unit 322 can be moved vertically upwards by the guide rails 358 as soon as a force acts on the grinding plate 334. Such a working position is in Fig. 10b shown.

[0050] In the fourth embodiment shown here, a flat, circumferential phase 370 is formed on the grinding plate 334 on its side facing the workpiece, which is slightly higher than the expected infeed depth. The phase 370 is designed so flat that the impacting wall section is captured and guided under the grinding plate 334. A phase angle between 10° and 40°, preferably 22.5°, has proven effective.

[0051] Attached to the side of the grinding plate 334 facing the workpiece is a conventional grinding wheel 335, which consists solely of the abrasive and a paper or linen pad that holds the abrasive. A grinding wheel with a flexible layer according to the first embodiment is not required here. This grinding wheel 335 also covers the phase 370.

[0052] The sequence of a grinding process using a device according to this fourth embodiment is described below as follows: The workpiece (not shown in detail here) is fed to the grinding unit 322 on a conveyor belt. The grinding plate 334 with the grinding wheel 335 attached to it rotates eccentrically, as described in detail in connection with the first embodiment. As soon as the workpiece hits the rotating grinding plate 334, the workpiece slides under the grinding plate 334 and lifts the entire grinding unit 322 vertically upwards. From then on, the grinding unit 322 presses onto the workpiece with its own weight while the actual grinding process is carried out. Consequently, the contact pressure exerted by the grinding wheel 335 on the workpiece is determined by the own weight of the grinding unit 322.However, because the grinding unit can move upwards if necessary, the contact pressure will never be particularly high, resulting in a uniform, undefined finish.

[0053] In the event that the workpiece is bent or has surface tolerances, the grinding unit 320 is moved upwards to a greater or lesser extent, whereby the contact pressure remains essentially constant and thus a uniform grinding pattern is produced on the entire workpiece.

[0054] The Fig. 12 The fifth embodiment shown differs from that shown in the Figures 10a , 10b and 11The fourth embodiment shown differs only in that a receiving device 472 for holding weights is provided on the grinding unit 422. By attaching a suitable weight, the contact pressure can be increased accordingly. Thus, the grinding unit 422 can be better adjusted to the respective workpiece.

[0055] In another sixth embodiment, not shown here, a pneumatic system with an air cylinder is provided on the grinding unit, which raises the grinding unit completely or partially depending on the set air pressure. This provides a further possibility for adjusting the contact pressure by reducing the weight of the grinding unit acting on the workpiece.

Claims

1. Apparatus for producing an undefined finish on a surface of a metal workpiece in a continuous process, comprising a grinding unit (322, 422) with at least one disk grinding unit (24, 124) having a grinding disk (34, 134, 334) and a grinding wheel (335) held on the grinding disk (34, 134, 334), wherein the grinding wheel (335) has abrasive means arranged parallel to the surface of the workpiece and wherein the grinding disk (34, 134, 334) is held eccentrically on the disk grinding unit (24, 124), with a transport device for linear transport of the workpiece under the grinding unit (322, 422) and with a tool bridge for mounting the grinding unit (322, 422) above the transport device, wherein the grinding unit (322, 422) is suspended in a displacement device (354) so that it can be displaced vertically upwards in such a way that the grinding unit (322, 422) deflects upwards when the workpiece acts on the grinding disk (34, 134, 334), characterized in that a friction brake (142) is provided on the disk grinding unit (24, 124) for braking the grinding disk (34, 134, 334), which comprises a shaft hose (144) and a friction ring (146) bearing against the grinding disk (34, 134, 334), wherein a spring steel coil (148) is integrated in the shaft hose (144).

2. Device according to claim 1, characterized in that an air pressure cylinder is provided between the displacement device and the grinding unit (322, 422), which partially lifts the grinding unit (322, 422).

3. Device according to claim 2, characterized in that the air pressure cylinder is adjustable in order to set the weight of the grinding unit (322, 422) acting on the workpiece.

4. Device according to any of the preceding claims, characterized in that means for receiving (472) at least one weight are provided on the grinding unit (322, 422).

5. Device according to any of the preceding claims, characterized in that a chamfer (370) is provided on one edge of a side of the grinding disk (34, 134, 334) facing the workpiece.

6. Device according to any of the preceding claims, characterized in that the displacement device (354) comprises a stopper (362) against which the sliding unit (322, 422) comes to rest.

7. Device according to at least one of the preceding claims, characterized in that the tool bridge (18, 218) has means for moving the grinding unit (22, 222) across the entire width of the workpiece transversely to the transport direction (16).

8. Device according to at least one of the preceding claims, characterized in that the disk grinding unit (24, 124) has an eccentric stroke of at least 6 mm, preferably 9 mm.

9. Device according to any of the preceding claims, characterized in that at least one vertically aligned slot (150) is provided in the upper region of the shaft hose (144).

10. Device according to one of the preceding claims, characterized in that the grinding disk (34, 134, 334) has a diameter of between 220 mm and 350 mm, preferably of 250 mm, and in that the disk grinding unit (24, 124) is designed for a maximum speed of 2000 rpm, preferably 1500 rpm.

11. Device according to at least one of the preceding claims, characterized in that a deburring unit (252) is provided on the tool bridge (218) in front of the grinding unit (322, 422) in the transport direction.

12. Device according to at least one of the preceding claims, characterized in that the grinding wheel (35) is designed as a fiber fleece grinding wheel.