Die press and method for treating a material

Abstract

A die press comprising a die (20), a first roller (31), a second roller (32), and a drive (16, 17). The die (20) has a raceway (24) provided with bores (21). The drive (16, 17) is designed to generate a relative movement between the die (20) and the rollers (31, 32), causing the first roller (31) and the second roller (32) to roll on the raceway (24) of the die (20). Each roller (31, 32) has a circumferential surface designed as a working surface (40). The working surface (40) comprises a first axial section (41) and a second axial section (42), wherein the working surface (40) in the second axial section (42) is set back radially relative to the working surface (40) in the first axial section (41). The invention also relates to a method for treating a material resting on a die (20).

Description

[0001] The invention relates to a die press and a method for treating a material.

[0002] Die presses are used to process various materials. Material on the surface of a die is processed by rolling rollers and pressed through the die's holes. Depending on parameters such as consistency, quantity, and composition, the material can be pressed into pellets or crushed. A common application of die presses is the production of pellets from biomass materials.

[0003] In conventional die presses, the working area of ​​a roller corresponds to the width of the raceway on the die, DE 20 2018 000 161 U1. Die presses are also known in which each roller covers only a portion of the raceway width, EP 2 902 100 A1. It has been found that known die presses do not achieve high efficiency in material processing in all application areas.

[0004] The invention is based on the objective of presenting a die press and a method for treating a material, with which the aforementioned disadvantages are reduced. This objective is achieved by the features of the independent claims. Advantageous embodiments are specified in the dependent claims.

[0005] A die press according to the invention comprises a die with holes, a first roller, a second roller, and a drive. The die with holes has a raceway provided with bores. The drive is designed to generate a relative movement between the die with holes and the rollers, such that the first and second rollers roll on the raceway of the die with holes. Each roller has a circumferential surface designed as a working surface. The working surface has a first axial section and a second axial section, wherein the working surface in the second axial section is offset radially relative to the working surface in the first axial section.

[0006] The invention is based on the concept of subjecting the material on the die to pre-compaction and post-compaction. When material on the surface of the die is rolled over by the recessed second axial section of the working surface, the pressure exerted on the material is lower than for material rolled over by the first axial section of the working surface. This lower pressure results in pre-compaction of the material. Post-compaction can follow the pre-compaction by rolling over this area of ​​the die with the first section of a trailing roller. The majority of the material does not pass through the pre-compaction but only through the holes of the die during the subsequent post-compaction. It has been shown that the combination of pre-compaction and post-compaction enables particularly efficient material processing.

[0007] The die press can be designed such that the first axial section of the first roller rolls on a different area of ​​the raceway than the first axial section of the second roller roll. Similarly, the second axial section of the first roller roll can roll on a different area of ​​the raceway than the second axial section of the second roller roll. There can be an overlap between the area of ​​the raceway on which the second axial section of the first roller rolls and the area on which the first axial section of the second roller rolls. In this way, pre-compaction can be achieved with the second axial section of the first roller roll, followed by post-compaction with the first axial section of the second roller roll.

[0008] The rollers have a direction of movement relative to the die when the die press is in operation. The width of the die's raceway forms a right angle with the instantaneous direction of movement. The axial direction of a roller can be aligned parallel to the width of the raceway. The raceway can be curved, so that the direction of movement of a roller changes during one revolution of the die press. The raceway can form a continuous path that is repeatedly traversed by the rollers on each revolution of the die press. Each axial segment of a roller can traverse the same width segment of the raceway on each revolution of the die press. The working surface of the first roller can extend across the entire width of the raceway. The working surface of the second roller can extend across the entire width of the raceway.In this way, the entire material on the die is subjected to either pre-compaction or post-compaction when rolled over by a roller.

[0009] The raceway of the die corresponds to the area in which the die is provided with holes through which the processed material passes. The holes can be arranged so that the raceway has a constant width.

[0010] The working surface of a roller is textured to allow the roller to machine the material. This textured surface can feature raised areas and depressions with sharp edges between them. It can be created by forming a pattern of depressions on the roller's outer surface. These depressions can include, for example, holes and / or grooves. The surface texture in the first axial section of the working surface can be the same as in the second axial section. Depending on the application, it can also be advantageous for the surface texture in the first axial section to differ from that in the second axial section.The surface structuring can be the same or different between the first roller and the second roller.

[0011] An axial section of a work surface can span a cylindrical shape that extends over the corresponding axial section of the roller. The diameter of the cylindrical shape in the first axial section of the work surface can correspond to the largest diameter of the roller. In the second axial section of the work surface, the cylindrical shape has a smaller diameter. The diameter of the roller in the first axial section of the work surface can, for example, be between 100 mm and 800 mm, preferably between 130 mm and 550 mm. The diameter of the roller in the second axial section of the work surface can be, for example, between 5 mm and 50 mm, preferably between 10 mm and 30 mm smaller than the diameter of the roller in the first axial section of the work surface.Additionally or alternatively, the diameter of the roller in the second axial section can be between 60% and 98%, preferably between 70% and 90%, of the diameter of the roller in the first axial section of the working surface.

[0012] In the case of an overlap between the second section of the first roller and the first section of the second roller, the material in the relevant width section can be pre-compacted by rolling over it with the first roller and then post-compacted by rolling over it with the second roller. The overlap between the second section of the first roller and the first section of the second roller can comprise at least 50%, preferably at least 80%, and more preferably at least 90% of the width of the first section of the second roller.In one embodiment, the width of the second section of the first roller corresponds to the width of the first section of the second roller.

[0013] The working surface of the first roller can cover the entire width of the die's raceway. This means that the raceway width is no greater than the distance between the opposite ends of the working surface. The axial extent of the roller can be greater than the width of the raceway. The roller can extend beyond the raceway on both sides. The roller can overlap a groove located adjacent to the raceway. The groove can extend around the circumference of the die. In one embodiment, such a circumferential groove is formed on both sides of the raceway. The axial extent of the roller can be such that the roller overlaps both circumferential grooves. The working surface can cover the width of the raceway without interruption. It is also possible for the working surface to have an axial gap at the transition between two sections.

[0014] The first roller can be designed such that the first axial section of the working surface and the second axial section of the working surface together constitute the entire working surface of the first roller. The roller can be designed such that the axial extent of the first axial section of the working surface differs from the axial extent of the second axial section of the working surface by no more than 20%, preferably no more than 10%, and more preferably no more than 5%. The percentage refers to the larger of the two axial sections. In one embodiment, the axial extent of the first axial section is identical to the axial extent of the second axial section. If the axial extents differ, the first section can have a larger extent than the second section.The invention encompasses embodiments in which the working surface of the first roller comprises more than two axial sections, wherein adjacent axial sections differ in diameter from one another.

[0015] Each characteristic mentioned in connection with a roller can be implemented in the first roller and / or the second roller. In a die press with more than two rollers, the characteristics can also be implemented individually or in combination in each of the rollers.

[0016] At the transition between two axial sections of the working surface, the roller may have a shoulder. This shoulder can form a transition between an axial section of the roller with a larger diameter and an axial section of the roller with a smaller diameter. Load peaks can occur in the area of ​​such a shoulder, which can lead to increased wear of the rollers or the die. To counteract this, the die may have a groove in the area where it is rolled over by such a shoulder on the roller. The groove can extend around the entire circumference of the die press so that, during one revolution of the die press, the position of the roller shoulder continuously coincides with the position of the groove.

[0017] The die press can be equipped with exactly two rollers. The axial sections of the working surfaces of the two rollers can be interchanged, so that in one width section of the track the first roller provides pre-compaction and the second roller provides post-compaction, and that in another width section of the track the second roller provides pre-compaction and the first roller provides post-compaction.

[0018] The die press can be equipped with more than two rollers that roll sequentially along the track. The rollers should be designed and arranged so that each width section of the track worked by a roller's working surface undergoes at least one pre-compaction and at least one post-compaction during one revolution of the die press. It is also possible for each width section of the track to undergo pre-compaction and post-compaction more than once during one revolution of the die press. In one embodiment, this is achieved by forming pairs of rollers that alternately perform pre-compaction and post-compaction. For example, the die press can comprise four rollers that interact in pairs in this manner.

[0019] The die press can be a pellet press. The die press can be designed as a flat die press. In a flat die press, the die extends in a plane, usually a horizontal one. The track can extend around a central axis of the die. The rollers can follow the track around the central axis, rolling around a horizontal axis in the process. Alternatively, the die press can be designed as a ring die press. In a ring die press, the die has the shape of a cylinder, with the rollers rolling around axes parallel to the cylinder's axis. Often, the rollers are located inside the ring die, and the material is pressed radially outward by the rollers.

[0020] The drive of the die press can be designed to drive a roller head on which a plurality of rollers are rotatably mounted. The rollers can rotate relative to the roller head while the roller head rotates relative to the die. In one embodiment, the die press includes a drive that actively drives the rotation of the rollers relative to the roller head. In another embodiment, the rollers are set into rotation by friction between the rollers and the material being processed relative to the roller head.

[0021] The invention also relates to a method for treating a material resting on a die with a first roller and a second roller. The die comprises a raceway provided with bores. The first roller and the second roller are driven such that they roll on the raceway of the die. Each roller has a circumferential surface designed as a working surface, the working surface having a first axial section and a second axial section. The working surface in the second axial section is set back radially relative to the working surface in the first axial section, so that the material is subjected to pre-compaction by the second axial section of the working surface and to post-compaction by the first axial section of the working surface.

[0022] The disclosure includes further developments of the method, which are described in connection with the die press according to the invention.

[0023] The invention is described below by way of example with reference to the accompanying drawings and advantageous embodiments. The drawings show: Fig. 1: a schematic representation of the structure of a die press according to the invention; Fig. 2: a top view of the roller head of the die press made of Fig. 1 Fig. 3: a top view of the die of the die press made of Fig. 1 ; Fig. 4: a first roller of the die press made of Fig. 1 ; Fig. 5: a second roller of the die press made of Fig. 1 ; Fig. 6, 7: the view according to Fig. 4, 5 in an alternative embodiment of the invention; Figs. 8, 9: the view according to Fig. 4, 5 in a further embodiment of the invention.

[0024] During a Fig. 1 In the flat die press shown, a machine housing 14 stands on a base 15. The machine housing 14 carries a drive shaft 16 designed as a vertical shaft, which is rotatably mounted in the machine housing 14. The drive shaft 16 can be set in rotation by a drive motor (not shown) via a drive 17. Four horizontal pivot pins 18 are connected to the drive shaft 16, of which are shown in the schematic representation of the Fig. 1 Two are visible. Four roller rollers 31, 32, 33, 34 are rotatably mounted on the axle journal 18, of which in Fig. 1 Only the first roller 31 and the third roller 33 are visible. The axle journals 18 and the rollers 31, 32, 33, 34 are components of the roller head 23 of the flat die press.

[0025] The rollers 31, 32, 33, 34 run on the top surface of a die 20, which is provided with a plurality of bores 21. The bores 21 extend from an inlet end facing the rollers 31, 32, 33, 34 through the die 20 to an outlet end on the underside of the die 20. When the drive shaft 16 rotates, the rollers 31, 32, 33, 34 move along a circular raceway on the top surface of the die 20.

[0026] The pellet press has a material inlet 22 through which a material, for example wood, can be introduced in a shredded form into the interior of the flat die press. The material falls onto the top of the die 20 and is compressed there by the pressure of the rollers 31, 32, 33, 34 and forced through the bores 21. This creates pellet strands that exit at the outlet ends of the bores 21 and are conveyed away through an outlet 27.

[0027] In Fig. 2 The roller head 23 of the flat die press is shown in a top view. The roller head 23 comprises a central body 46, which is in Fig. 1 The central body 46 is in a rotationally fixed connection with the main shaft 16. The four axle journals 18 extend outwards from the central body 46, with an angle of 90° between each pair of axle journals 18. The axle journals 18 extend in a plane that is orthogonal to the main shaft 16.

[0028] Each roller 31, 32, 33, 34 comprises a working surface 40 formed on a cylindrical surface of the roller 31, 32, 33, 34. Each working surface 40 has a first axial section 41 and a second axial section 42, each extending along a section of the axle journal 18. The first axial section 41 has a larger diameter, which corresponds to the largest diameter of the roller 31, 32, 33, 34. The second axial section 42 has a diameter slightly smaller than the diameter of the first axial section 41. The first axial section 41 and the second axial section 42 together form the axial extension 43 of the working surface 40.

[0029] The working surfaces 40 of the rollers 31, 32, 33, 34 are provided with a surface structure by which the rollers 31, 32, 33, 34 interact with the material to be treated. In the first axial section 41, the surface structure in this embodiment is formed by a plurality of short blind bores. In the second axial section 42, the surface structure is formed by a plurality of grooves extending over the axial extent of the second axial section 42.

[0030] In Fig. 3 The die 20, on which the rollers 31, 32, 33, 34 roll, is shown in a top view. The die 20 includes a raceway 24, which extends over the surface of the die 20 in the form of a closed annular track. In the area of ​​the raceway 24, the die 20 is provided with a plurality of bores, which are Fig. 3 The raceway 24 is schematically indicated by hatching. The raceway 24 has a width 25, which extends transversely to the direction of the raceway 24. The raceway 24 corresponds to the area of ​​the die 20 in which the die 20 is provided with bores through which the material passes during operation of the flat die press.

[0031] The width 25 of the raceway 24 corresponds to the axial extent 43 of the working surface 40 of the rollers 31, 32, 33, 34. The entire material lying on the raceway 24 is therefore rolled over by the rollers 31, 32, 33, 34 during one complete revolution of the roller head 23.

[0032] The Fig. 4, 5 The schematic views of the first roller 31 and the second roller 32 above the die 20 are shown. In the first roller 31, the first axial section 41 of the working surface 40 is arranged radially outside the roller head 23, and the second axial section 42 of the working surface 40 is arranged radially inside the roller head 23. In the second roller 32, the arrangement is reversed. The first axial section 41 is arranged radially inside the roller head 23, and the second axial section 42 is arranged radially outside the roller head 23.

[0033] If a section of the raceway 24 is first rolled over by the first roller 31 and then by the second roller 32, the second axial section 42 of the first roller 31 causes a pre-compaction of the material in an inner area of ​​the raceway 24. The pre-compacted material is shortly thereafter rolled over by the first axial section 41 of the second roller 32 and thus further compacted.

[0034] Conversely, the first axial section 41 in the outer area of ​​the raceway 42 rolls over a layer of material that was pre-compacted shortly before by the second axial section 42 of the fourth roller 34. The first axial section 41 of the first roller 31 causes further compaction of the pre-compacted material. Particularly during this further compaction, the pressure exerted on the layer of material is so great that the material passes through the bores 21 of the die 20 and is formed into pellets.

[0035] In the operation of the flat die press, new material is continuously fed in, falling between two roller rollers onto the top of the die 20. The freshly fed material is subject to pre-compaction, in particular, as it only falls onto the area of ​​the raceway 24 after being rolled over by the preceding roller roller. This area is then rolled over by the second section 42 of a roller roller 31, 32, 33, 34.

[0036] Each pair of two consecutive rollers thus creates a sequence of pre-compaction and post-compaction in a section of the track. For the pairs consisting of leading roller 31 and trailing roller 32, as well as leading roller 33 and trailing roller 34, the sequence of pre-compaction and post-compaction takes place in the inner section of the track. For the pairs consisting of leading roller 32 and trailing roller 33, as well as leading roller 34 and trailing roller 31, the sequence of pre-compaction and post-compaction takes place in the outer section of the track 24.

[0037] In the Fig. 6, 7 An alternative embodiment is shown in which the raceway 24 has no bores in the area over which the shoulder 47 between the first axial section 41 and the second axial section 42 of the working surface 40 is rolled. Instead, a groove 45 is formed in this radial position of the die 20, extending in the form of a closed ring over the surface of the die 20. By allowing the material resting on the die 20 to move into the groove 45, the mechanical load on the rollers 31, 32, 33, 34 in the area of ​​the shoulder 47 is reduced, which has a beneficial effect on the service life of the rollers 31, 32, 33, 34 and the die 20.

[0038] In the further embodiment in the Fig. 8, 9An inner annular groove 48 is formed within the raceway 24, and an outer annular groove 49 is formed outside the raceway 24. The rollers 31, 32, 33, 34 project inwards and outwards beyond the raceway 24 and overlap with the annular grooves 48, 49. Similar to the groove 45 in the center of the raceway, the inner annular groove 48 and the outer annular groove 49 serve to reduce wear on the rollers 31, 32, 33, 34 and the die 20.

Claims

1. Die press with a die (20), a first roller (31), a second roller (32) and a drive (16, 17), wherein the die (20) has a raceway (24) provided with bores (21), wherein the drive (16, 17) is designed to generate a relative movement between the die (20) and the rollers (31, 32) such that the first roller (31) and the second roller (32) roll on the raceway (24) of the die (20), wherein each roller (31, 32) has a circumferential surface designed as a working surface (40), wherein the working surface (40) comprises a first axial section (41) and a second axial section (42), wherein the working surface (40) in the second axial section (42) is radially oriented relative to the working surface (40) is set back in the first axial section (41).

2. Die press according to claim 1, wherein the first axial section (41) of the first roller roll (31) rolls on a different area of ​​the raceway (24) than the first axial section (41) of the second roller roll (32).

3. Die press according to claim 1 or 2, wherein the second axial section (42) of the first roller (31) rolls on a different area of ​​the raceway (24) than the second axial section (42) of the second roller (32).

4. Die press according to one of claims 1 to 3, wherein there is an overlap between the area of ​​the raceway (24) on which the second axial section (42) of the first roller roll (31) rolls and the area of ​​the raceway (24) on which the first axial section (41) of the second roller roll (32) rolls.

5. Die press according to one of claims 1 to 4, wherein the axial extent (43) of the working surfaces (40) of the first roller (31) and the second roller (32) covers the width (25) of the raceway (24).

6. Die press according to claim 5, wherein the first roller (31) and the second roller (32) extend beyond the width of the raceway (24) and overlap with an annular groove (48, 49) arranged laterally to the raceway (24).

7. Die press according to one of claims 1 to 6, wherein the working surfaces (40) of the first roller (31) and the second roller (32) are provided with a surface structuring.

8. Die press according to one of claims 1 to 7, wherein the diameter of the roller (31, 32) in the second axial section (42) of the working surface (40) is between 5 mm and 50 mm, preferably between 10 mm and 30 mm smaller than the diameter of the roller (31, 32) in the first axial section (41) of the working surface (40).

9. Die press according to one of claims 1 to 8, wherein the diameter of the roller (31, 32) in the second axial section (42) of the working surface is between 60% and 98%, preferably between 70% and 90% of the diameter of the roller (31, 32) in the first axial section (41) of the working surface (40).

10. Die press according to one of claims 1 to 9, wherein the diameter of the working surface (40) in the first axial section (41) corresponds to the largest diameter of the roller (31, 32).

11. Die press according to one of claims 1 to 10, wherein the axial extent of the first axial section (41) of the working surface (40) differs by no more than 20%, preferably by no more than 10%, and more preferably by no more than 5% from the axial extent of the second axial section (42) of the working surface (40).

12. Die press according to one of claims 1 to 11, wherein the raceway (24) of the die (20) has a recess (45) extending over the circumference of the die press, which is opposite a shoulder (47) between the first axial section (41) and the second axial section (42) of a roller (31, 32).

13. Die press according to one of claims 1 to 12, wherein the die press is designed as a flat die press with more than two roller rollers (31, 32, 33, 34), wherein two successive roller rollers (31, 32, 33, 34) are each designed in pairs to subject material lying on a region of the die (20) to pre-compaction and post-compaction.

14. Method for treating a material resting on a die (20) with a first roller (31) and a second roller (32), wherein the die (20) has a raceway (24) provided with bores (21), wherein a relative movement is generated between the die and the rollers (31, 32) such that the first roller (31) and the second roller (32) roll on the raceway (24) of the die (20), wherein each roller (31, 32) has a circumferential surface designed as a working surface (40), wherein the working surface (40) comprises a first axial section (41) and a second axial section (42), wherein the working surface (40) in the second axial section (42) is set back in the radial direction relative to the working surface (40) in the first axial section (41).so that the material is subjected to pre-compaction with the second axial section (42) of the working surface (40) and that the material is subjected to post-compaction with the first axial section (41) of the working surface (40).

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