Device for processing a workpiece

Abstract

The invention relates to a device (1) for machining a workpiece (2), which preferably consists at least partially of wood, wood-based material, or plastic, comprising a machining unit (10) for machining the workpiece (2), a conveying unit (20) for conveying the workpiece (2) relative to the machining unit (10), wherein the conveying unit (20) has at least one endlessly circulating belt (30) having an outer circumferential surface (32) which is configured to bear against the respective workpiece (2) during conveying, and a guide unit (22) for guiding the belt (30) along a circular path. The belt (30) is elastically deformable in a direction transverse to its outer circumferential surface (32).

Description

Technical area

[0001] The invention relates to a device (1) for machining a workpiece (2), which preferably consists at least in sections of wood, wood-based material or plastic, according to the preamble of claim 1. Such a device is known from the document EP1842637 A1. State of the art

[0002] In the furniture and construction component industries, workpieces are often processed in processing devices that transport them along processing units. Such processing devices often have a conveyor track and a so-called top pressure system to convey the workpieces. The conveyor track and top pressure system can comprise various conveying devices, such as conveyor chains, conveyor belts, roller conveyors, etc.

[0003] For example, EP 2 614 940 A1 discloses a processing device of this type, which features multiple conveyor tracks and top pressures. Such devices have proven their worth in practice. However, it has been shown that adapting the devices to varying workpiece thicknesses requires considerable design effort.

[0004] Further workpiece support devices are known from EP 3 839 287 A1 and JP H08 66901 A. Description of the invention

[0005] The invention is based on the object of providing a device for machining a workpiece of the type mentioned above, which has a simple construction and a good adaptability to varying workpiece thicknesses.

[0006] This object is achieved according to the invention by a device for machining a workpiece according to claim 1. Particularly preferred developments of the invention are specified in the dependent claims.

[0007] The invention is based on the idea of ​​equipping the at least one belt of the conveyor unit with a functionality for adapting to varying workpiece thicknesses. For this purpose, the invention provides that the belt is elastically deformable in a direction transverse to its outer circumferential surface.

[0008] This allows the design of the processing device or conveyor unit to be significantly simplified. Previously, the belts were typically mounted on rollers, which in turn were mounted on deflectable roller levers, allowing different workpiece thicknesses to be conveyed. Such complex substructures are no longer necessary with the belt according to the invention, as the belt's elasticity allows it to compensate for varying workpiece thicknesses. Furthermore, a more uniform contact pressure is achieved. This not only prevents pressure peaks, but also allows shorter workpieces (in the conveying direction) to be conveyed.

[0009] According to a further development of the invention, the elastic stiffness of the belt increases at least once in a direction transverse to its outer circumferential surface, at least in some sections, with increasing deformation. This provides, in a sense, a hybrid belt which has a relatively low stiffness in a first deformation region and a greater stiffness in at least one further deformation region (with increasing deformation). The belt can thus fulfill a dual function, namely enabling particularly good adaptability in its first deformation region and providing sufficient stability for clamping workpieces in its further deformation region. It is particularly preferred that the stiffness in the further deformation region is at least five times greater than the stiffness in the first deformation region, although the invention is not limited thereto.

[0010] The belt can be designed in different ways within the scope of the invention. The belt further comprises at least two layers which have different elastic stiffnesses in a direction transverse to its outer circumferential surface. A middle layer has a lower elastic stiffness in a direction transverse to the outer circumferential surface than an outer layer. The layer structure allows for a particularly good combination of different mechanical properties. For example, the outer layers can have a sufficiently high resistance to the loads encountered, while at least one inner layer can have a lower stiffness in order to achieve the desired elastic deformability. A wide variety of other layer structures are also possible within the scope of the invention.

[0011] It is particularly preferred that at least two layers of the belt be made of different materials. This allows the different elastic stiffnesses of the layers to be achieved with ease of manufacture, while additional functionalities can also be achieved through appropriate material selection.

[0012] Alternatively or additionally, according to a further development of the invention, the belt is provided with one or more cavities. By providing one or more cavities, the stiffness of the belt can be specifically controlled, so that the desired elastic deformability can be achieved in a particularly simple manner and, if necessary, even using only a single material.

[0013] It is particularly preferred that adjacent cavities are each separated by a web, which preferably has a smaller thickness than the cavities in the direction of belt extension. The webs allow sufficient basic stiffness of the belt to be maintained, while a suitable arrangement of the webs can also fulfill additional functions, such as stabilizing the belt in the area of ​​contact surfaces with gears. At the same time, the preferably relatively narrow (compared to the cavities) dimensioning of the webs enables a sufficient reduction in belt stiffness in the respective area.

[0014] According to a further development of the invention, the guide unit comprises, at least in some areas, a sliding guide on which an inner circumferential surface of the belt slides. This results in a particularly simple design of the device according to the invention, since, for example, no support rollers, deflection levers, or the like are required; instead, the belt simply slides on a suitable sliding guide.

[0015] It is particularly preferred that the sliding guide has a sliding surface coated with a sliding coating, such as PTFE, and / or hard anodized. This not only results in a high level of durability for the sliding guide, but also makes the belt particularly quiet and requires low drive forces. Furthermore, the durability of the belt is also increased.

[0016] In this respect, it is also preferred that the inner circumferential surface of the belt is at least partially coated with a sliding coating such as in particular PTFE and / or polyamide.

[0017] According to a further development of the invention, the guide unit can have a roller guide at least in some areas, which is particularly advantageous at very high conveying speeds or pressure forces. The inventive design of the conveyor belt allows the rollers to be advantageously fixedly mounted, thereby simplifying the construction.

[0018] With regard to the conveying concept, the belt can be designed in various ways, in principle also as a V-belt. According to a further development of the invention, however, it is particularly preferred for the belt to be designed as a toothed belt. This allows for significantly more precise conveying operation, in which the advance of the belt (if driven) can be precisely coordinated with other advance elements of the device. It should be noted that the use of a V-belt was not considered in previous devices due to the usually complicated support structures, but is now advantageously enabled by the inventive concept.

[0019] According to a further development of the invention, the conveyor unit further comprises a support unit configured to support the workpiece during conveying and preferably comprising an endless circulating element, such as, in particular, a chain. The combination of the support element with the at least one belt results in secure guidance and stabilization of the workpiece, which ultimately enables precise and rapid machining of the workpiece with a simple design. The use of a conveyor chain enables a highly dynamic conveying process with high durability and precision.

[0020] The at least one belt described above can in principle be a passive belt that is not actively driven, but merely rolls on a conveyed workpiece to support or clamp it. According to a further development of the invention, however, it is provided that the conveyor unit has at least one drive for driving the belt, so that this can also contribute to the feed of the workpiece. Alternatively or additionally, the device can also have at least one drive for driving the support unit, wherein the drive for driving the belt and the drive for driving the support unit are preferably synchronized with one another. It is precisely the combination of both drives that results in a precise and simultaneously highly dynamic conveying process that combines outstanding machining quality with a high workpiece throughput. Short description of the drawings

[0021] Fig. 1shows schematically a side view of an apparatus for machining a workpiece according to an embodiment of the invention; Fig. 2 shows schematically a section of a side view of a belt; Fig. 3 shows schematically various partial views of a belt; Fig. 4 shows schematically various partial views of a belt. Detailed description of embodiments

[0022] Embodiments of the invention are described in detail below with reference to the accompanying figures.

[0023] A device 1 for machining a workpiece 2 is shown in Fig. 1shown schematically in a side view. The device 1 is used for processing workpieces 2, which consist, for example, of wood, wood-based materials, plastic, or similar composite materials, such as those widely used in the furniture and construction element industries. The workpieces 2 can be, for example, plate- or strip-shaped.

[0024] For processing the workpieces 2, the device 1 initially comprises a processing unit 10. This can perform a wide variety of processing operations, such as machining such as drilling, milling, sawing, etc., but also finishing operations such as applying coating material, painting, printing, etc. For this purpose, the processing unit 10 can also combine several processing means.

[0025] In addition, a conveyor unit 20 is provided, which conveys the respective workpiece 2 along the processing unit 10 or through it. In the present embodiment, the conveyor unit 20 comprises a support unit, which in the present embodiment comprises a conveyor chain 42. In the present embodiment, chain plates 44 are attached to the conveyor chain 42, on which the respective workpieces 2 are supported. The conveyor chain 42 is driven in rotation by means of a drive and moves in Fig. 1 from left to right (or vice versa). The conveyor chain 42 can be supported, for example, by suitable rollers on a guide (not shown) or support unit 40.

[0026] Furthermore, the conveyor unit 20 in the present embodiment comprises a so-called top pressure, which is formed by one or more circulating belts 30, which are guided along a circulating path by a beam-shaped guide unit 22. A conveying gap for the respective workpieces 2 is defined between the belt 32 and the conveyor chain 42 or the chain plates 44, such that the belt 30 rests against the respective workpiece 2 with its outer circumferential surface 32, while the workpiece 2 is supported on at least one chain plate 44.

[0027] The belt slides in the region of its inner circumferential surface 33 on a sliding surface 26 of a sliding guide 24 arranged on the guide unit 22. In the present embodiment, the sliding surface 26 is hard-anodized and coated with PTFE (Teflon). Likewise, the inner circumferential surface 323 of the belt 30 is coated with PTFE and / or polyamide (PAR / PAZ) in the present embodiment. Although not shown in the figures, the guide unit (22) can, at least in some areas—alternatively or additionally—have a roller guide whose rollers are preferably fixedly mounted.

[0028] Furthermore, the belt is deflected via deflection rollers 27 at the ends of the guide unit 22, wherein in the area of ​​at least one deflection roller (right in Fig. 1 ) a drive 28 for driving the deflection pulley 27 and thus the belt 30.

[0029] The drive 28 is advantageously synchronized with the drive 29, so that the conveyor chain 42 and the belt 32 are driven synchronously with each other and can convey a workpiece 2 with corresponding precision. To enable a particularly synchronous operation, the belt 33 is designed as a toothed belt, which is Figures 2 to 4 is best seen. In this case, the idler pulleys 27 have a complementary tooth profile for secure and precise engagement between the belt 30 and the idler pulleys 27.

[0030] According to the invention, the belt itself is elastically deformable in a direction transverse to its outer circumferential surface 32. This elastic deformability can be achieved, for example, by suitable material selection, by a suitable layer structure or by various structural measures on or in the belt, which can be illustrated by way of example with reference to Figures 2 to 4 described.

[0031] The Fig. 2The belt 30 shown in a schematic and partial side view has a plurality of layers 34, 35 and 36. According to the invention, the middle layer 34 has a lower elastic stiffness in a direction transverse to its outer circumferential surface 32 than the outer layer 36 and / or the inner layer 35. This enables a deformation behavior in which the belt 30, when subjected to a load occurring transversely to its outer circumferential surface 32, initially has a relatively low stiffness, which primarily results from the comparatively low elastic stiffness of the middle layer 34. As soon as the middle layer 34 is largely or completely compressed, the overall stiffness of the belt 30 increases sharply transversely to the direction of extension of the outer circumferential surface 32 and can then, for example, be five times or more of the previous stiffness.

[0032] Alternatively or additionally, the belt can Fig. 3illustrated structure. In this embodiment, the belt has a meandering cavity 38 predominantly in its interior, although the cavity 38 may also have a variety of other geometries. Furthermore, a foam may also be used to define cavities.

[0033] By providing the cavity, the belt again exhibits comparatively low stiffness when subjected to a load transverse to its outer circumferential surface 32. As soon as the cavity has largely or completely closed due to the load, the stiffness of the belt 30 increases significantly, so that it is, in a sense, a hybrid belt, analogous to the embodiment described above.

[0034] Another embodiment of the belt is in Fig. 4illustrated. In this embodiment, the belt 30 has a plurality of cavities 38 transverse to its endless direction of rotation, which are separated from one another by webs 39. It should be noted that the number, geometry, and direction of extension of the cavities can be varied in many ways within the scope of the invention. In any case, the cavities result in a targeted reduction in the stiffness of the belt 30 transverse to its outer circumferential surface 32, with the stiffness of the belt in turn increasing significantly as soon as the cavities have largely or completely closed as a result of an external load.

[0035] The above-described exemplary configurations of the belt 30 allow the belt to deform elastically when a workpiece is fed into the conveying gap between the conveyor chain 42 and the belt 30. This allows the belt to flexibly adapt to varying workpiece thicknesses, so that the design of the device according to the invention can be significantly simplified.

Claims

1. Device (1) for processing a workpiece (2) which preferably consists at least in part of wood, wood-based material or plastic, comprising: a processing unit (10) for processing the workpiece (2), a conveying unit (20) for conveying the workpiece (2) relative to the processing unit (10), wherein the conveying unit (20) has: at least one endlessly circulating belt (30) which has an outer circumferential surface (32) which is designed to be in contact with the respective workpiece (2) during conveying, and a guide unit (22) for guiding the belt (30) along a circulation path, characterised in that the belt (30) is elastically deformable in a direction transverse to its outer circumferential surface (32) and the belt (30) has at least two layers (34, 36) which exhibit different elastic stiffnesses in a direction transverse to its outer circumferential surface (32), wherein a middle layer (34) has a lower elastic stiffness in a direction transverse to the outer circumferential surface (32) than an outer layer (36).

2. Device according to claim 1, wherein the elastic stiffness of the belt (30) in a direction transverse to its outer circumferential surface (32) increases at least once, at least in sections, with increasing deformation.

3. Device according to claim 1, wherein at least two layers (34, 36) of the belt (30) have different materials.

4. Device according to one of the preceding claims, wherein the belt (30) has one or more cavities (38).

5. Device according to claim 4, wherein adjacent cavities (38) are in each case separated by a web (39) which preferably has a lesser thickness in the direction of extension of the belt (30) than the cavities.

6. Device according to one of the preceding claims, wherein the guide unit (22) has, at least in some areas, a sliding guide (24) on which an inner circumferential surface (33) of the belt (30) slides.

7. Device according to claim 6, wherein the sliding guide (24) has a sliding surface (26) which is coated with a sliding coating such as PTFE in particular and / or is hard-anodised.

8. Device according to one of the preceding claims, wherein an inner circumferential surface (33) of the belt (30) is coated, at least in some areas, with a sliding coating such as PTFE in particular and / or polyamide.

9. Device according to one of the preceding claims, wherein the guide unit (22) has, at least in some areas, a roller guide, wherein the rollers are preferably firmly mounted.

10. Device according to one of the preceding claims, wherein the belt (30) is designed as a toothed belt.

11. Device according to one of the preceding claims, wherein the conveying unit (20) further comprises a support unit (40) which is designed to support the workpiece (2) during conveying and preferably has a continuous circulation element (42) such as in particular a chain.

12. Device according to one of the preceding claims, wherein the conveying unit (20) has at least one drive (28) for driving the belt (30) and / or at least one drive (29) for driving the support unit, wherein the drives (28, 29) are preferably synchronised.

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