Direct-driven spindle

Abstract

The invention relates to a direct-driven spindle (1) for machining workpieces, having a rotary drive, which comprises an armature (2) and a stator (3), and a rotor shaft (4), which is assigned to the at least one tool holder (5) for a tool (6) mounted in a floating manner, wherein the rotor shaft (4) is rotatably mounted in a housing (7), in particular by means of two bearings (8). In order to create a powerful, particularly compact rotary drive, it is proposed that the armature (2) is formed by a cup-shaped rotor rim (9) that is fastened to the rotor shaft end face (10) opposite the at least one tool holder (5) and mounted in a floating manner.

Description

[0001] Direct drive

[0002]

[0003] Technical field

[0004] The invention relates to a device, in particular a direct-drive spindle for workpiece machining, comprising a rotary drive (an electric motor) with an armature and a stator, and a rotor shaft to which at least one tool holder for a cantilevered tool is assigned, wherein the rotor shaft is rotatably mounted in a housing, in particular by means of two bearings. It is in particular a direct-drive rotor shaft / spindle for machine tools for workpiece machining, for example for sawing, milling, grinding any materials such as wood, metal, plastic, glass, and the like.

[0005] State of the art

[0006] The direct-drive spindle according to the invention is intended, for example, for use in twin-spindle circular saws, which have become established in the field of sawing technology for processing round and squared timber in recent decades. Circular saw blades and milling cutters can be used as tools. Devices of this type are known, for example, from EP 3917710 A2, DE 4038 129 A, and EP 0785 051 A. The main advantages of this technology lie in a cut surface with the best surface properties, precise cutting accuracy, and very high cutting performance. The circular saw itself can be designed as a group saw, i.e., perform several cuts simultaneously with several saw blades arranged on a common tool, thus enabling particularly high throughput with relatively simple machines.Due to the limitations of the circular saw blades and their maximum practical diameter, twin-spindle circular saws have a restricted cutting height. Therefore, the cutting process is carried out from two opposite sides, using two saw groups, with the saw blades always working in pairs in a common cutting plane. The workpiece is fed through the twin-spindle circular saw between the saw spindle axes by a suitable conveying drive.

[0007] Furthermore, the two saw groups are arranged with an offset in the cutting direction, resulting in a vertical overlap of a few millimeters between the centrifugal circles of the circular saw blades working in the same cutting plane, ensuring a clean cut through the timber. This overlap, free from lateral offset, is a prerequisite for a flat surface on the sawn timber.

[0008] To ensure this, the radial distance between the saw spindles of the saw assemblies must be adjustable, depending on the circular saw blade diameter. The drive units must therefore be correspondingly slim to allow for axially parallel arrangement, which, however, increases the overall length of the drives and thus their weight. According to the teaching of EP3917710 A2, the armature is fixed to the saw spindle, and the stator is fixed to the housing between a fixed bearing and a floating bearing of the saw spindle, with the saw tool being cantilevered, i.e., supported only on one side, on the saw spindle. The spindle and motor thus form a single unit located between the bearings.

[0009] Acoustic monitoring is a known method for monitoring circular saws. However, this type of monitoring is very prone to interference and errors, which is why users have often taken this expensive system out of service. Description of the invention

[0010] The invention is therefore based on the objective of creating a direct-drive spindle with a lighter, more powerful, and particularly compact rotary drive.

[0011] The invention solves the problem by forming the armature from a cup-shaped rotor rim, which is attached to the rotor shaft end face opposite the at least one tool holder and is cantilevered, i.e., mounted exclusively on one side.

[0012] According to the invention, the rotor shaft is mounted in the housing by means of bearings. At one end of the rotor shaft is assigned at least one tool holder for the cantilevered tool, and at the other end is the cup-shaped rotor rim forming the armature of the electric motor, which, like the tool, is cantilevered, i.e., mounted exclusively on one side by means of the rotor shaft. Separate bearings for the rotor rim are therefore not required. This design offers advantages in terms of weight and simultaneously enables a compact construction. The cup-shaped rotor rim reduces the weight of the armature to a minimum. A cup-shaped rotor rim has the advantage of good magnetic field distribution and can efficiently absorb the mechanical load caused by rotation. This design is particularly compact, yet ideally suited for the high-performance applications in question, where high speeds and efficiency are required.

[0013] The direct-drive spindle according to the invention allows for the most compact design possible with the smallest possible installation space per unit of power, a significantly reduced overall length, and a lower weight per unit of power. The reduced weight enables higher adjustment speeds when used as frame saws, for example, in twin-spindle circular saws. With such saws, trees can be processed at very high cutting speeds of up to 1000 m / s. Due to the floating bearing of the armature, i.e., the rotor rim, temperature-related changes in the armature's length are no longer a significant factor, which greatly improves the cutting performance of the direct-drive spindle.

[0014] As a result of the more compact design and lower weight, a curved steering system can be implemented for a direct-drive spindle according to the invention. A kinematic displacement of the armature transversely to its axis of rotation causes a gyroscopic effect, which, like the inertial force of a gyroscope in its rotational position, counteracts any change in position. This load is absorbed by the rotor shaft bearings and transferred into the housing. The rotor shaft bearings are designed as support bearings, for which purpose the two bearings are preloaded against each other in the direction of the rotor's longitudinal axis. Typically, two angular contact ball bearings or tapered roller bearings arranged in a mirror image are preloaded against each other. If the center of pressure is located between the bearing points, it is called an X-arrangement; outside the bearing points, it is called an O-arrangement.In an O-arrangement, the bearing can absorb a larger tilting moment than in an X-arrangement, because in an O-arrangement the distance between the pressure centers is greater, which is why an O-arrangement should also be provided in the present case.

[0015] The direct-drive spindle according to the invention can be used in twin-spindle circular saws (Duo or Quattro), in variously arranged single-shaft circular saws, in edging circular saws, in edging chipping machines and in high-speed edgers up to 1000 m / min cutting speed, which cutting speeds require maximum speeds of up to 6000 rpm.

[0016] Preferably, the rotor rim has a cylindrical shell, the outer surface of which is fitted with permanent magnets from a permanent magnet synchronous machine that forms the rotary drive. The permanent magnet-excited rotor rim is thus equipped with permanent magnets that are integrated with the rotor, thereby generating the magnetic field without external excitation. In this context, the cup-shaped rotor rim offers the advantage of good magnetic field distribution. This design allows for a compact form factor when used in high-performance applications, such as this one, where high speeds and power outputs are required.

[0017] Permanent magnet synchronous machines with a rotor rim according to the invention can cover a power range of up to several MW.

[0018] Permanent magnet synchronous machines generally offer higher efficiency and better power density compared to conventional asynchronous machines. They allow for high torque density and precise control.

[0019] The rotor rim can have a cylindrical shell, the inner surface of which forms a pot-shaped interior that extends away from the rotor shaft along its longitudinal axis and is open towards the inside of the housing. The pot-shaped rotor rim is thus open away from the rotor shaft, with the interior of the pot being accessible from the housing. Various housing-mounted, i.e., non-rotating, components can be housed within the pot in a space-saving manner.

[0020] To cool the rotor rim, a radial fan can be attached to the rotor shaft side of the rim, which is fixed to the rotor rim. The radial fan ensures the circulation of a fluid within the pot.

[0021] The housing can be equipped with a tube projecting into the interior of the pot and fixed to the housing in a rotationally stable manner. This tube is positioned at a distance from the inner surface of the casing, creating a cooling channel between the inner surface and the outer surface of the tube. The tube acts as a guide for the fluid and can also accommodate the aforementioned non-rotating components within its interior, saving space. This ensures proper cooling of the rotor rim, on whose outer surface the permanent magnets are located and which is heated by the magnetic flux.

[0022] Additionally or alternatively, a spiral tube, arranged with clearance to the inner surface of the tube, can be associated with the tube, in particular its outer shell surface, and can be connected to a coolant circuit. Thus, compared to the prior art, internal air cooling can be implemented without the very complex liquid cooling system that would otherwise have to be introduced into the rotor via rotary feedthroughs, since the cooling elements, except for the optional fan, do not have to rotate with the rotor rim, and rotary feedthroughs are therefore unnecessary.

[0023] In order to be able to adjust the distance of tools along the rotor shaft axis quickly and easily, it is advantageous if the rotor shaft comprises at least two rotor shaft units connected to each other in a rotationally fixed manner, each of which has at least one tool holder for a tool on its working side, wherein at least one rotor shaft unit is displaceable along a rotor longitudinal axis (15), relative to the rotor shaft and relative to the other rotor shaft unit.

[0024] Each rotor shaft unit can be moved along the rotor's longitudinal axis by either a hydraulic cylinder or an electric cylinder.

[0025] The respective cylinder housing can be fixedly arranged, and the piston can be connected to the rotor shaft units via rotary bearings to prevent rotation of the piston relative to the rotor shaft units, ensuring displacement parallel to the rotor longitudinal axis. At least the pistons penetrate the inner chamber.

[0026] To enable quick tool or tool group changes, the tool holder can comprise an interchangeably mounted tool, in particular an interchangeably mounted circular saw blade group, wherein the tool holder is detachably attached to the rotor shaft, which has a corresponding counterpart in the form of a conical axle stub, via a quick-change cone and is secured in the mounting position with a screw connection coaxial to the rotor's longitudinal axis, wherein a head of the screw connection is mounted in the tool holder so as to be freely rotatable but axially secured for loosening the tool holder. Brief description of the invention

[0027] The invention is illustrated in the drawing as an example. It shows

[0028] Fig. 1 Direct-drive spindle for sawing workpieces in a schematic longitudinal section,

[0029] Fig. 2 shows an enlarged section of Fig. 1 in schematic longitudinal section, Fig. 3 shows a design variant of the direct-drive spindle from Fig. 1, and Fig. 4 shows an exploded view of a tube including a spiral tube that can be inserted into the interior of the pot in oblique view.

[0030] Fig. 5 and 6. a multi-spindle circular saw with four directly driven spindles according to the invention, adjustable on a frame, in side and front view.

[0031] Ways to implement the invention

[0032] The direct-drive spindle 1 for workpiece machining comprises a rotary drive, i.e., an electric motor, comprising an armature 2 and a stator 3, and a rotor shaft 4 to which at least one tool holder 5 for a cantilevered tool 6 is assigned. The rotor shaft 4 is rotatably mounted in a housing 7 by means of two bearings 8. The direct-drive spindle 1 shown in the drawing represents a circular saw, in particular a twin-spindle circular saw, which is equipped with several saw blades. The armature 2 is formed by a cup-shaped rotor rim 9, which is attached, in particular screwed, to the rotor shaft end face 10 opposite the at least one tool holder 5 and is cantilevered, i.e., supported only on one side. For clarification, it should be noted that only the rotor shaft 4 is supported in the housing 7.The rotor rim 9 itself is bearingless and is attached at its end face to the rotor shaft end face 10 opposite the tool holder 5, i.e. rigidly connected to the rotor shaft 4, here screwed in place.

[0033] The rotor rim 9 has a cylindrical shell 11, on the outer surface 12 of which permanent magnets 13 of a permanent magnet synchronous machine forming the rotary drive are arranged. The permanent magnets 13 can also be integrated into or embedded in the rotor rim 9. The inner surface 14 of the cylindrical shell 11 also forms a pot-shaped interior 17, extending away from the rotor shaft 4 along its longitudinal axis 15 and open towards the interior of the housing 16. This means that the rotor rim 9 has a low mass.

[0034] For cooling the pot interior 17, a radial fan 18 is assigned to the rotor rim 9 on the rotor shaft side, which is connected to the rotor rim 9 in a rotationally fixed manner, in particular by screwing it on.

[0035] Furthermore, a tube 20, projecting into the interior of the pot 17 and arranged in a rotationally fixed manner on the housing 7, in particular on a housing cover 19, is associated with the housing 7. This tube is positioned at a distance from the inner surface of the shell 14 such that a cooling channel 22 is formed between the inner surface of the shell 14 and the outer surface 21 of the tube shell. A cooling medium, for example air, is conveyed through this cooling channel 22 by the radial fan 18. This cooling medium can be conveyed, for example, through radial openings 23 in the housing-side tube 20 into the interior of the tube 24 and from there drawn back in by the radial fan 18.

[0036] For the purpose of heat dissipation, a spiral tube 25 arranged with clearance to the inner surface 14 of the tube shell can be assigned to the outer shell surface 21, which can be connected to a schematically represented coolant circuit, which in addition to the spiral tube 25 includes coolant lines 26, a pump 27 and a heat exchanger 28 for heat dissipation.

[0037] The rotor shaft 4 can comprise at least two rotor shaft units 4a, 4b that are rotationally fixed to one another, each having at least one tool holder 5 for a tool 6 on its working side, wherein at least one rotor shaft unit 4a, 4b is displaceable along the rotor longitudinal axis 15 relative to the rotor shaft 4 and relative to the other rotor shaft unit 4b, 4a. The rotor shaft units 4b, 4a are telescopically adjustable within the rotor shaft 4 and are rotationally fixed to each other and to the rotor shaft 4, for example via splined connections.

[0038] For the displacement of each rotor shaft unit 4a, 4b along the rotor longitudinal axis 15, a hydraulic cylinder is provided in particular. The cylinders 29 of the hydraulic cylinders are in particular arranged fixedly to the housing, and the pistons 30 of the hydraulic cylinders can be connected to the rotor shaft units 4a, 4b via rotary bearings 31 to prevent rotation of the pistons 30 relative to the rotor shaft units 4a, 4b in a manner that prevents displacement parallel to the rotor longitudinal axis.

[0039] The tool holder 5 can comprise an interchangeably mounted tool, in particular an interchangeably mounted circular saw blade assembly (Fig. 3), wherein the tool holder 5 can be detachably attached to the rotor shaft 4, which has a corresponding counterpart in the form of a conical stub axle 33, via a quick-change cone 32 and secured in the mounting position by a screw connection 34 coaxial with the rotor longitudinal axis 15, wherein a head 35 of the screw connection 34 for releasing the tool holder 5 from the conical stub axle 33 can be freely rotatable but axially secured in the tool holder 5. For this purpose, a washer 36 is provided to secure the head 35 in the removal direction.

[0040] The housing 7 can preferably be equipped with vibration monitoring for the direct-drive spindle I, located between the bearings 8. Reliable monitoring can be ensured if the housing 7 is equipped with two vibration sensors 41, preferably arranged on a common sensor adapter 40, and in particular directly on the housing. One of the vibration sensors 41 is arranged to detect radial vibrations, and the other is arranged to detect axial vibrations.

[0041] Such monitoring, as described in the invention, offers significant economic advantages during the operation of the direct-drive spindle 1, since it allows the material feed to be stopped immediately and the respective rotor shaft 4 or the tool spindle to be shut down immediately in the event of tool damage caused by frequently occurring foreign objects in the wood (e.g., stones, nails, projectiles, or splinters). This prevents unnecessary damage to neighboring tools, significant and unnecessary scrap, and unnecessary downtime.

[0042] However, for this described vibration detection to function reliably (because any error would be counterproductive and cause even greater damage), certain prerequisites are required in the rotor shaft 4, namely a high-precision spindle bearing, a mono-bearing block (this enables distortion-free mounting in the surrounding machine frame, which is an indispensable prerequisite for the use of high-precision preloaded spindle bearings in conjunction with an electric motor), slightly preloaded bearings in an O-arrangement (as already described), cooling and lubrication of the bearing connection parts (shaft and housing) via appropriate connections 42, and a high degree of balancing of the rotor shaft 4.

[0043] For successful and accurate vibration detection, using an empirically determined but consistently recurring vibration profile of ten vibration parameters for the event of damage, and ensuring that this profile matches the input profile and the associated signal output, the system remains permanently stable and reliable for detection under the stated conditions. Furthermore, the vibration monitoring can also be reliably used to monitor the bearings themselves.

[0044] Figures 4 and 5 show a frame 43 on which, in the illustrated embodiment, four direct-drive spindles 1 according to the invention are arranged such that, for example, a tree trunk can be cleanly cut or trimmed in the desired manner. The direct-drive spindles 1 can be arranged in almost any configuration:

[0045] Examples include: twin-spindle circular saw in side arrangement (duo), twin-spindle circular saw in top arbor arrangement (quadro), single-shaft circular saw (top arbor), single-shaft circular saw (bottom arbor), edging circular saw in side arrangement, edging circular saw in top arbor arrangement, edging chipper in side arrangement, edging chipper in top arbor arrangement, high-speed edgers up to 1000 m / min due to machine-related maximum speeds up to 6000 rpm resulting from the suitability of compact bearings as a result of the ideally integrated overall design. (without torque-transmitting, radially load-causing, wear-prone and speed-limiting machine elements such as couplings, drive shafts, belt drives and the like, planer cutters, corner cutters or drum cutters)

[0046] The illustrated frame 43 essentially comprises a base frame 44 with transverse guides 45 on which two machine columns 46 rest, which can be moved along the transverse guides 43 by means of actuating drives 47. Each machine column 46 has a vertical guide 48 along which monolinear slides 49, one for each directly driven spindle 1, can be moved by means of associated actuating drives 47. The directly driven spindles 1 are firmly anchored to the monolinear slides 48, in particular by bolting.

[0047] In particular, the illustrated monolinear slides with adjustable preload are a prerequisite for the design of a single machine stand (column) per compact spindle pair (duo arrangement). In a spire arrangement, two opposing machine stands enable a quadro arrangement. In any case, the monolinear slide allows for the highest possible linear alignment. The enormous reduction in machine weight achievable with the invention (70% less weight with the same performance) combined with the simultaneous increase in structural rigidity opens up the possibility of faster adjustment processes and thus, especially in applications as edgers, previously unattainable.

[0048] Peak performance.

Claims

Patent claims 1. Direct-drive spindle (1) for workpiece machining with a rotary drive comprising an armature (2) and a stator (3) and with a rotor shaft (4) to which at least one tool holder (5) for a cantilevered tool (6) is assigned, wherein the rotor shaft (4) is rotatably mounted in a housing (7), in particular by means of two bearings (8), characterized in that the armature (2) is formed by a cup-shaped rotor rim (9) which is attached to the rotor shaft end face (10) opposite the at least one tool holder (5) and is cantilevered.

2. Direct-drive spindle (1) according to claim 1, characterized in that the rotor rim (9) has a cylindrical shell (11) whose outer shell surface (12) is assigned permanent magnets (13) of a permanent excitation synchronous machine forming the rotary drive.

3. Direct-drive spindle (1) according to claim 2, characterized in that the rotor rim (9) has a cylindrical shell (11) whose inner surface (14) spans a pot interior (17) extending away from the rotor shaft (4) along its longitudinal axis (15) and open towards the interior of the housing (16).

4. Direct-drive spindle (1) according to one of claims 1 to 3, characterized in that a radial fan (18) is assigned to the rotor rim (9) on the rotor shaft side, which is connected to the rotor rim (9) in a rotationally fixed manner.

5. Direct-drive spindle (1) according to claim 3 or 4, characterized in that a tube (20) projecting into the pot interior (17) and arranged rotationally fixed to the housing (7) is associated with the housing (7), which is arranged at a distance from the inner surface (14) of the shell such that a cooling channel (22) is formed between the inner surface (14) of the shell and the outer surface (21) of the tube shell.

6. Direct-drive spindle (1) according to claim 5, characterized in that a spiral tube (25) arranged with clearance to the inner surface (14) of the tube shell is associated with the outer surface (21) of the tube shell and can be connected to a coolant circuit.

7. Direct-drive spindle (1) according to one of claims 1 to 6, characterized in that the rotor shaft (4) comprises at least two rotor shaft units (4a, 4b) connected to each other in a rotationally fixed manner, each having at least one tool holder (5) for a tool (6) on its working side, wherein at least one rotor shaft unit (4a, 4b) is displaceable along a rotor longitudinal axis (15), relative to the rotor shaft (4) and relative to the other rotor shaft unit (4b, 4a).

8. Direct-drive spindle (1) according to claim 7, characterized in that a hydraulic cylinder / electric cylinder is provided for each rotor shaft unit (4a, 4b) along the rotor longitudinal axis (15).

9. Direct-drive spindle (1) according to claim 7, characterized in that cylinders (29) of the hydraulic cylinders are arranged fixed to the housing and pistons (30) of the hydraulic cylinders are connected to the rotor shaft units (4a, 4b) via rotary bearings (31) to prevent rotation of the pistons (30) relative to the rotor shaft units (4a, 4b) in a manner that prevents displacement parallel to the rotor longitudinal axis.

10. Direct-drive spindle (1) according to one of claims 1 to 6, characterized in that the tool holder (5) comprises an interchangeably mounted tool, in particular an interchangeably mounted circular saw blade assembly, wherein the tool holder (5) is detachably fastened to the rotor shaft (4) having a corresponding counterpart in the form of a conical axle stub (33) via a quick-change cone (32) and is secured in the assembly position with a screw connection (34) coaxial to the rotor longitudinal axis (15), wherein a head (35) of the screw connection (34) for releasing the tool holder (5) is mounted in the tool holder (5) so as to be freely rotatable but axially secured.

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