WO2012168414A1

WO2012168414A1 - Method, apparatus and system for reducing vibration in a rotary system of a tool

Info

Publication number: WO2012168414A1
Application number: PCT/EP2012/060869
Authority: WO
Inventors: Prof. Dr.-Ing. Norbert SEITZ
Original assignee: Carnehammar, Prof. Dr. Lars Bertil
Priority date: 2011-06-10
Filing date: 2012-06-08
Publication date: 2012-12-13

Abstract

A method of reducing vibration in a rotary system of a tool, comprising balancing said rotary system, characterized by providing a rotational element comprising a chamber having a fulcrum on a rotational axis of said rotational element, comprising a circumferential balancing area and being partially filled with an amount of a thixotropic balancing substance. A corresponding apparatus and system.

Description

Method, Apparatus and System for Reducing Vibration in a Rotary System of a Tool

Field of the Invention

Embodiments of the invention described herein relate generally to reducing vibration, and more particularly to a method, an apparatus and a system for reducing vibration in a rotary system of a tool such as a power tool or machine tool.

Background of the Invention

A tool is a device for producing an item or achieving a task, but that is not consumed in the process of producing. The tool may be powered manually or by a power source delivering energy, for example in the form of electrical energy, that is electricity.

The tool may be comprised within a housing, for example a case or building such as a plant. The tool may be comprised in a system, for example a production line such as an assembly line.

The tool may comprise a drive unit, and a tooling unit or tooling units; for example a drilling machine, and drills having different diameters.

The tool, or tooling unit, may rotate at a few revolutions per minute (rpm) or several thousand revolutions per second. The tool may consume energy in a range from a few watts (W) or kilowatts (KW) to several megawatts (MW).

Vibration is a major factor in a tool. Vibration negatively effects durability that is service interval and life time, safety and comfort. With regard to safety, vibration has a direct influence on stability and may cause material fatigue and damage. With regard to comfort, vibration has a direct influence on noise and may increase a level of noise. Moreover, vibration-induced noise may be amplified by the system comprising the tool. Furthermore, vibration may negatively effect health of a person operating the tool.

A main source of vibration is a rotary system of the tool, comprising, for example, a drive unit and a tooling unit. The rotary system may comprise a shaft, a bearing, a rotor or a combination thereof. Vibrations may comprise rotation- speed-dependent vibrations generally originating from the rotary system. Vibrations may damage rolling-element bearings, for example ball bearings or roller bearings, used, for example, as bearings, or seals.

In order to reduce vibration, the rotary system may initially be balanced during production of the rotary system by selectively removing material from a rotating element of the rotary system such that its centre of gravity (CofG) is moved to its centre of rotation (CofR), that is fulcrum. Removing material may comprise abrading, for example grinding, material from the rotating element, or drilling a hole into the rotating elements, or a combination thereof. However, the removing step is an additional step in production, requiring time and increasing cost, particularly in large-volume production.

Moreover, owing to wear and tear of the rotary system, or collection of particles, for example dirt, on the rotary system, vibration in the tool generally increases over time. In more detail, owing to wear and tear of a rotating element, for example a drill and grinding wheel, its CofG moves away from the CofR over time causing an imbalance causing vibration.

WO 2010/029112 discloses a method for reducing vibration in a rotary system of an article processing machine, for example a washing machine.

For these and other reasons, there is a need for the invention as set forth in the following in the embodiments. Summary of the Invention

The invention aims to provide a method, an apparatus and a system for reducing vibration in a rotary system of a tool.

An aspect of the invention is a method of reducing vibration in a rotary

system 120, 130, 140, 150 of a tool 100; 300; 400; 500, such as a power tool or machine tool, for example an electric tool, hydraulic tool or pneumatic tool, comprising balancing said rotary system 120, 130, 140, 150, characterized by providing a rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200 comprising a chamber 210 having a fulcrum on a rotational axis 240 of said rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200, comprising a circumferential balancing area 220 and being partially filled with an amount of a thixotropic balancing substance 230. Another aspect of the invention is a method, further comprising rotating said rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200 about the rotational axis 240, such that said thixotropic balancing substance 230 liquefies and distributes itself along the circumferential balancing area 220, and an imbalance of said rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200 is reduced.

Another aspect of the invention is a method, wherein said rotational axis 240 is oriented horizontally; or said rotational axis 240 is oriented vertically.

Another aspect of the invention is a method, wherein said rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200 is an original element of said rotary system 120, 130, 140, 150, a replacement element of said rotary system 120, 130, 140, 150, or a supplemental element to said rotary system 120, 130, 140, 150; said rotational element 130, 152 is a hollow shaft or tubular shaft; said rotational element 130, 152 is an articulated shaft, for example a cardan shaft; or a combination thereof.

Another aspect of the invention is a method, wherein the supplemental element is disc-shaped; or the supplemental element is ring-shaped.

Another aspect of the invention is a method, wherein said rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200 is a shaft 130, 152; said rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200 is a rotor 124 of said tool 100; 300; 400; 500; said rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200 is a gear wheel; said rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200 is a bearing 135; 145; or a combination thereof.

Another aspect of the invention is a method, wherein said chamber 210 is annular or ring-shaped, or cylindrical; said chamber 210 has a cross section being rectangular, square, semicircle-shaped, bell-shaped or circular; said chamber 210 has a diameter of between 0.005 m and 2 m, or between 0.01 m and 1 m, or between 0.02 m and 0.5 m, or between 0.05 m and 0.2 m, or 0.1 m; said chamber 210 has a length of between 0.01 m and 1 m, or between 0.02 m and 0.5 m, or between 0.05 m and 0.2 m, or 0.1 m; or a combination thereof.

Another aspect of the invention is a method, wherein said amount of said thixotropic balancing substance 230 is between 0.001 kg and 1000 kg, or between 0.002 kg and 500 kg, or between 0.005 kg and 200 kg, or between 0.01 kg and 100 kg, or between 0.02 kg and 50 kg, or between 0.05 kg and 20 kg, or between 0.1 kg and 10 kg, or between 0.2 kg and 5 kg, or between 0.5 kg and 2 kg, or 1 kg; said chamber 210 is filled with the amount of said thixotropic balancing substance 230 to between 1 % and 90 %, or between 10 % and 80 %, or between 25 % and 75 %, or 50 %; or a combination thereof.

Another aspect of the invention is an apparatus for reducing vibration in a rotary system 120, 130, 140, 150 of a tool 100; 300; 400; 500, characterized by a rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200 comprising a chamber 210 having a fulcrum on a rotational axis 240 of said rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200, comprising a circumferential balancing area 220 and being partially filled with an amount of a thixotropic balancing substance 230.

Another aspect of the invention is a rotary system 120, 130, 140, 150 of a tool 100; 300; 400; 500, for reducing vibration in said rotary system 120, 130, 140, 150, characterized by a rotational element 120, 124, 130, 135, 140, 142,

144, 145, 150, 152, 154; 200 comprising a chamber 210 having a fulcrum on a rotational axis 240 of said rotational element 120, 124, 130, 135, 140, 142, 144,

145, 150, 152, 154; 200, comprising a circumferential balancing area 220 and being partially filled with an amount of a thixotropic balancing substance 230.

Brief Description of the Several Views of the Drawing

While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are depicted in the appended drawing, in order to illustrate the manner in which embodiments of the invention are obtained. Understanding that the drawing depicts only typical embodiments of the invention, that are not necessarily drawn to scale, and, therefore, are not to be considered limiting of its scope, embodiments will be described and explained with additional specificity and detail through use of the accompanying drawing in which :

Fig. 1 shows a schematic view of a tool, to which the invention may be applied;

Fig. 2 shows, for a preferred embodiment of the invention, a cross-sectional view of the cylindrical chamber at an initial point in time; Fig. 3 shows, for the preferred embodiment of the invention, a cross-sectional view of the cylindrical chamber at a point in time, when the thixotropic balancing substance is distributed along the circumferential balancing area of the chamber;

Fig. 4 shows a cross-sectional view of a chamber in a rotational element according to yet another embodiment of the invention;

Fig. 5 shows a cross-sectional view of a chamber in a rotational element according to yet another embodiment of the invention;

Fig. 6 shows a cross-sectional view of a chamber in another rotational element according to yet another embodiment of the invention;

Fig. 7 shows a cross-sectional view of another chamber in a rotational element according to yet another embodiment of the invention;

Fig. 8 shows a cross-sectional view of another chamber in a rotational element according to yet another embodiment of the invention;

Fig. 9 shows a cross-sectional view of yet another chamber in a rotational element according to yet another embodiment of the invention;

Fig. 10 shows a cross-sectional view of another chamber in another rotational element according to yet another embodiment of the invention;

Fig. 11 shows a cross-sectional view of a juicer according to an embodiment of the invention under test;

Fig. 12 shows an exemplary representation of deflections of an original juicer over time;

Fig. 13 shows an exemplary representation of deflections of a modified juicer over time with supplemental rotational element;

Fig. 14 shows an exemplary representation of deflections of the modified juicer over time with supplemental rotational element and added imbalance;

Fig. 15 shows an exemplary representation of deflections of the modified juicer over time with supplemental rotational element comprising an amount of the balancing substance and added imbalance;

Fig. 16 shows a cross-sectional view of an angle grinder according to an embodiment of the invention under test; Fig. 17 shows an exemplary representation of deflections of an original angle grinder over time without supplemental system;

Fig. 18 shows an exemplary representation of deflections of the original angle grinder over time with original supplemental system;

Fig. 19 shows an exemplary representation of deflections of a modified angle grinder over time with supplemental rotational element comprising an amount of the balancing substance; and

Fig. 20 shows a cross-sectional view of an injection-moulding machine according to an embodiment of the invention. Detailed Description of the Invention

In the detailed description of the embodiments, reference is made to the accompanying drawing which forms a part hereof and shows, by way of illustration, specific embodiments in which the invention may be practiced. In order to show the structures of the embodiments most clearly, the drawing included herein is a diagrammatic representation of inventive articles. Thus, actual appearance of the fabricated structures may appear different while still incorporating essential structures of embodiments. Moreover, the drawing shows only the structures necessary to understand the embodiments. Additional structures known in the art have not been included to maintain clarity of the drawings. It is also to be understood, that features and/or elements depicted herein are illustrated with particular dimensions relative to one another for purposes of simplicity and ease of understanding, and that actual dimensions may differ substantially from that illustrated herein. In the drawing, like numerals describe substantially similar components throughout the several views. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those of skill in the art to practice the invention. Other embodiments may be utilized and structural, logical or electrical changes or combinations thereof may be made without departing from the scope of the invention.

Moreover, it is to be understood, that the various embodiments of the invention, although different, are not necessarily mutually exclusive. For example, a particular element, feature, structure, characteristic, integer or step, or group of elements, features, structures, characteristics, integers or steps described in one embodiment may be included within other embodiments. Furthermore, it is to be understood, that embodiments of the invention may be implemented using different technologies. Also, the term "exemplary" is merely meant as an example, rather than the best or optimal. The detailed description is, therefore, not to be taken in a limiting sense.

Throughout this specification the word„comprise" or variations such as

"comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

In the description and claims, the terms "include", "have", "with" or other variants thereof may be used. It is to be understood, that such terms are intended to be inclusive in a manner similar to the term "comprise".

In the description and claims, the terms "coupled" and "connected", along with derivatives such as "communicatively coupled" may be used. It is to be understood, that these terms are not intended as synonyms for each other.

Rather, in particular embodiments, "connected" may be used to indicate, that two or more elements are in direct physical or electrical contact with each other.

However, "coupled" may also mean that two or more elements are not in direct contact with each other, but yet still co-operate or interact with each other.

In the description and claims, terms, such as "upper", "lower", "first", "second", etc., may be only used for descriptive purposes and are not to be construed as limiting. The embodiments of a device or article described herein can be manufactured, used, or shipped in a number of positions and orientations.

Fig. 1 shows a schematic view of a tool 100, to which the invention may be applied. The tool 100 may comprise a housing 110. The housing 110 may be a case or building such as a plant. The tool 100 comprises a drive unit 120 for providing rotary energy at a shaft 130 having a fulcrum on a rotational axis 240. As indicated in Fig. 1, the drive unit 120 may comprise a rotor 124 housed in a stator 122 and coupled to the shaft 130. The drive unit 120 may typically be powered by electrical energy delivered from a power supply (not shown), for example a battery such as a rechargeable battery or a mains supply. However, the drive unit 120 may comprise a turbine (not shown) with one, two, three or more turbine wheels housed in a turbine housing. The drive unit 120 may be powered by diverse sources of power comprising, for example, hydraulic power and pneumatic power. The turbine may be powered by gas such as natural gas or bio gas, or steam. The drive unit 120 may comprise an internal combustion engine powered by, for example, gas, such as natural gas or bio gas, oil, gasoline or diesel. The tool 100 further comprises a tooling unit 140 coupled to the drive unit 120 for receiving the rotary energy, and directly or indirectly supporting a tool or an item to be processed. The tooling unit 140 may be partially or completely housed in the housing 110, as indicated in Fig. 1. The tooling unit 140 may comprise a collet chuck such as a scroll chuck for receiving and clamping the tool or item. The tool 100 may comprise one, two, three or more support elements 180 having bearings 135 and being arranged along the shaft 130 for supporting the shaft 130. Rotating elements of the tool 100 such as rotor 124, shaft 130, bearing 135 and tooling unit 140 form a rotary system of the tool 100. The rotary system of the tool 100 may optionally comprise a gear box 150 arranged between the drive unit 120 and the tooling unit 140 for coupling the drive unit 120 and the tooling unit 140. The gear box 150 may be an indexing gear box, that is a shift gear box. The gear box 150 may convert a rotational speed of the drive unit 120 to a rotational speed of the power generating unit 140. The gear box 150 may increase or decrease the rotational speed. The gear box 150 may or may not change direction of the rotation. The gear box 150 may redirect the rotary energy into another direction. The gear box 150 may distribute the rotary energy among one, two, three or more drive units 120 and one, two, three or more power generating units 140. The tool 100 may further comprise a percussion unit or hammer unit (not shown).

The tool 100 may be oriented horizontally, vertically, or at any suitable angle.

The tool 100 may generate rotational power. The tool 100 may generate rotational power in the range from a few watts (W) to several megawatts (MW), for example kilowatts (KW). The rotational power may be used directly for processing the item or indirectly for handling the tool or item. Processing may comprise tooling, for example cutting such as sawing, drilling such as boring, grinding, turning or lathing, milling, and planing. Handling may comprise, for example, moving a tool mount, for example a collet chuck such as a scroll chuck, door or lid, and safety device. The tool 100 may transform a primary energy, that is input energy such as electrical energy, into a secondary energy, that is output energy such as rotational energy.

The tool 100 may be stationary.

The tool 100 may be a machine tool comprising a circular saw bench, pillar drilling machine or column drilling machine such as a pillar boring machine or column boring machine, turning machine or lathe such as a numerically controlled (NC) turning machine or computer numerically controlled (CNC) turning machine, milling machine such as a NC milling machine or CNC milling machine, and planning machine, for example in a workshop. Further, a machine tool may comprise an injection-moulding machine for producing, for example, items comprising plastics.

Further, the tool 100 may be portable.

The tool 100 may comprise a grinder such as a power grinder or coffee grinder, mixer such as a hand mixer, stand mixer, power chopper or meat mincing machine, that is meat chopper, blender such as a hand blender or immersion blender, food processor, food slicer, and juicer such as a power juicer or juice centrifuge.

Further, the tool 100 may be hand-held.

The tool 100 may comprise a grinder such as an angular grinder, sander, polisher, saw, such as a circular hand saw, drilling machine or boring machine such as a power drill, that is an electric drill or a cordless drill, percussion drilling machine, and hammer drilling machine, for example pneumatic hammer drilling machine, power screwdriver such as an electric screwdriver or a cordless screwdriver, drywall screwdriver, and power planer such as an electric planer.

Thus, it may be employed at home, in an office, a business, a shop, a workshop, a building site, or a constructions site.

Furthermore, the tool 100 may be employed mobile.

The tool 100 may comprise a mowing machine such as a lawn-mower, and agricultural machine or farm machine such as a harvester.

Thus, the tool 100 may, among other things, be employed in processing items and achieving tasks. According to embodiments of the invention, one, two, three or more rotational elements 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154 of the tool 100 comprise one, two, three or more chambers 210 having a fulcrum on a rotational axis 240, comprising a circumferential balancing area 220 and being partially filled with an amount of a thixotropic balancing substance 230. The one, two, three or more rotational elements 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154 comprising one, two, three or more chambers 210 may comprise metal, for example steel, titanium, copper or aluminium, or composite material, for example glass-fibre-reinforced material or carbon-fibre-reinforced material, or synthetic material, for example plastics or plexiglas. The one, two, three or more rotational elements 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154 comprising one, two, three or more chambers 210 may replace original rotational elements 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154 of the rotational system. The one, two, three or more rotational elements 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154 comprising one, two, three or more chambers 210 may be supplemental elements to the rotational system.

The chamber 210 may be caved into the rotational element such as rotor 124 or gear wheel. The chamber 210 may be situated in a shaft 130, such as a hollow shaft, tubular shaft or threaded rod, and extend partially or fully, such as substantially fully, along the hollow shaft or tubular shaft.

The circumferential balancing area 220 may comprise a nanostructure for improving movability and flow of the thixotropic balancing substance 230, said nanostructure being, for example, formed by a material, such as a varnish, comprising nanoparticles, or imprinted on said circumferential balancing area 220. The thixotropic balancing substance 230 operates in the chamber 210. Owing to vibration, the thixotropic balancing substance 230 distributes itself along the circumferential balancing area 220, such that a CofG 250 moves towards the rotational axis 240, that is CofR, of the rotational element 120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200, such as the shaft 130, and the vibration is reduced or minimized or eliminated.

Fig. 2 shows, for a preferred embodiment of the invention, a cross-sectional view of the cylindrical chamber 210 at an initial point in time, when the thixotropic balancing substance 230 partially fills the chamber 210. The thixotropic balancing substance 230 may be evenly distributed along the circumferential balancing area 220 as shown in Fig. 2. For a vertical rotational axis 240, the thixotropic balancing substance 230 may partially fill the chamber 210 to an even level perpendicular to the rotational axis 240. For a horizontal rotational axis 240, the thixotropic balancing substance 230 may partially fill the chamber 210 to an even level along the rotational axis 240. However, the thixotropic balancing

substance 230 may partially fill the chamber 210 in any other manner. Owing to an imbalance of the rotational element 200 or the rotary system, a CofG 250 is offset from the rotational axis 240, that is CofR.

Fig. 3 shows, for the preferred embodiment of the invention, a cross-sectional view of the cylindrical chamber 210 at a point in time, when the thixotropic balancing substance 230 is distributed along the circumferential balancing area 220 of the chamber 210, such that the vibration is reduced. As the rotational element 200 rotates about the rotational axis 240, the thixotropic balancing substance 230 liquefies owing to vibration in the rotary system and distributes itself along the circumferential balancing area 220 of the chamber 210, such that an imbalance of the rotational element 200 is reduced, and, thus, the vibration is reduced. The CofG 250 moves towards the rotational axis 240, that is CofR. When the vibration is reduced, the thixotropic balancing substance 230 may solidify and maintain its position and distribution on the circumferential balancing area 220. Thus, during operation of the rotary system, its balance is constantly adjusted.

The amount of the thixotropic balancing substance 230 may be between approximately 0.001 kg and approximately 1000 kg, or between approximately 0.002 kg and approximately 500 kg, or between approximately 0.005 kg and approximately 200 kg, or between approximately 0.01 kg and approximately 100 kg, or between approximately 0.02 kg and approximately 50 kg, or between approximately 0.05 kg and approximately 20 kg, or between approximately 0.1 kg and approximately 10 kg, or between approximately 0.2 kg and approximately 5 kg, or between approximately 0.5 kg and approximately 2 kg, or approximately 1 kg. The chamber 210 may be filled with the amount of said thixotropic balancing substance 230 to between approximately 1 % and approximately 90 %, or between approximately 10 % and approximately 80 %, or between

approximately 25 % and approximately 75 %, or approximately 50 %. Fig. 4 shows a cross-sectional view of a chamber 210 in a rotational element 200, 204 according to yet another embodiment of the invention. The chamber 210 is caved into the rotational element 200, 204, such as a flywheel, a gear wheel or an additional element, for example a container or vessel. The chamber 210 is annular or ring-shaped. The chamber 210 may have a cross section being rectangular, square (not shown), semicircle-shaped (not shown), bell-shaped (not shown), circular (not shown) or the like.

Fig. 5 shows a cross-sectional view of a chamber 210 in a rotational element 200, 204 according to yet another embodiment of the invention. With reference to Fig. 4, the rotational element 200, 204 comprises a centre hole 260. The centre hole 260 may be circular, square (not shown), hexagonal (not shown) or the like. The centre hole 260 of the rotational element 200, 204 may receive a shaft for coupling the rotational element 200, 204 to the rotational system.

The rotational element 200, 204 may comprise a rotor of a tool (not shown), and the centre hole 260 houses a shaft (not shown). In a preferred embodiment, the rotational element 200, 204 may be injection-moulded in one, two, three or more parts, and the chamber 210 may be sealed by a sealing element. The sealing element may be a snap-in or snap-on sealing element. In another preferred embodiment, the rotational element 200, 204 may be part of a rotating element of the tool 100, such as the rotor 124, the shaft 130 or the tooling unit 140, and the chamber 210 may be sealed by a sealing element. The sealing element may be welded to the rotational element, for example using friction-welding, laser- welding or ultrasonic-welding.

Fig. 6 shows a cross-sectional view of a chamber 210 in another rotational element 200, 206 according to yet another embodiment of the invention. The chamber 210 is caved into the other rotational element 200, 206, such as a flywheel, a gear wheel or an additional element, for example a container or vessel. The chamber 210 is cylindrical. The chamber 210 may have a cross section being rectangular, square (not shown), semicircle-shaped (not shown), bell-shaped (not shown), circular (not shown) or the like.

Fig. 7 shows a cross-sectional view of another chamber 210 in a rotational element 200, 204 according to yet another embodiment of the invention. With reference to Fig. 4, the rotational element 200, 204 comprises an opening 270 providing access to the chamber 210. The opening 270 may be circumferential. The opening is situated, such that the balancing substance 230 is and remains contained in the chamber 210.

Fig. 8 shows a cross-sectional view of another chamber 210 in a rotational element 200, 204 according to yet another embodiment of the invention. With reference to Fig. 5, the rotational element 200, 204 comprises an opening 270 providing access to the chamber 210 as discussed with reference to Fig. 7.

The rotational element 200, 204 may comprise a rotational element of the tool 100 as described with reference to Fig. 5.

Fig. 9 shows a cross-sectional view of yet another chamber 210 in a rotational element 200, 204 according to yet another embodiment of the invention. With reference to Fig. 5, the rotational element 200, 204 comprises an opening 270 providing access to the chamber 210 as discussed with reference to Figs 7 and 8.

Fig. 10 shows a cross-sectional view of another chamber 210 in a rotational element 200, 206 according to yet another embodiment of the invention. With reference to Fig. 6, the rotational element 200, 206 comprises an opening 270 providing access to the chamber 210 as discussed with reference to Fig. 7.

The thixotropic balancing substance 230 may be a thixotropic tyre balancing composition disclosed in EP patent application no. 0 281 252 and corresponding US patent no. 4,867,792, which are hereby incorporated by reference in their entirety, having a yield stress value between 1 Pa and 260 Pa being capable of balancing tyres by being able to flow under the influence of the vibrations induced when a heavy spot on the tyre hits the road surface.

The thixotropic balancing substance 230 may be a tyre gel balancing composition disclosed in European patent no. 0 557 365 and US corresponding patent no. 5,431,726, which are hereby incorporated by reference in their entirety, having a storage modulus of between 3000 and 15000 Pa and the specific gravity less than 1000 kg/m^ in the temperature range between -20 and +90 °C, preferably its storage modulus is about 9000 Pa, being capable of balancing tyres by being able to flow under the vibrations caused by imbalance in a wheel assembly. The composition preferably comprises a mixture of: 1) paraffinic oils, polybutene oils, polyolesters or polyol ethers; 2) hydrophobic or hydrophilic fumed silica; 3) polyalkyl-methacrylates, styrene-ethylene-propylene block copolymers or polyhydroxycarboxylic acid derivatives; and optionally corrosion inhibitors and antioxidants.

The thixotropic balancing substance 230 may be one of the tyre balancing compositions disclosed in European patent no. 1 196 299 Bl and corresponding US publication nos US-2005-0159534-A1 and US-2010-0252174-A1, which are hereby incorporated by reference in their entirety, having improved balancing properties and comprise a visco-plastic gel and solid bodies having an average smallest dimension in the range of 0.5-5 mm; preferably 1-4 mm, more preferably around 3 mm. When applied in a layer to the inside of a motor vehicle tyre, the compositions act by allowing the solid bodies move through the gel and to concentrate in areas to counteract imbalances. The solid bodies preferably have an average ratio alpha between their smallest and their largest dimension of alpha < = 2, more preferably alpha < = 1.5, especially around 1. The visco-plastic gel preferably has a storage modulus (G') between 1000 Pa and 25000 Pa at 22 °C, a loss modulus (G") smaller than the storage modulus, and a critical yield stress above 3 Pa at 22 °C. The bodies may be shaped as prolate or oblate ellipsoids, cylinders, rectangular parallelipipeds, or spheres, or mixtures of such bodies; they may have an apparent specific gravity in the range of 500- 3000 kg/m³, preferably 600-2000 kg/m³, in particular 700-1000 kg/m³, especially 800-900 kg/m³; they may be made from polyolefins, polystyrene, polyvinyl chloride, polyamide, rubber or glass. The weight ratio between the solid bodies and the gel is from 10 : 1 to 1 : 10, preferably from 5: 1 to 1 : 5, in particular from 2: 1 to 3 : 1, such as from 1 : 1 to 1 : 2.

The thixotropic balancing substance 230 may be one of the visco-elastic tyre balancing compositions disclosed in international patent application

WO 2010/055097, which is hereby incorporated by reference in its entirety, comprising 1) 85 to 97 % by weight of a glycol ether component comprising one or more ethylene/propylene glycol copolymer ethers of the general formula (I) or the general (II) or mixtures thereof R-0 {[CH(Ci.i3)CH₂-0-]_m [CH₂-CH₂-0-]„}H (I) R,-(0- {[CH(CHOCH₂-0-]_m [CH₂-CH₂-0-]_n}H)₂ (II) wherein R is hydrogen or an alkyl group of 2-8 carbon atoms; R i is an alkylene moiety of 2-8 carbon atoms in which the two substituents are not carried on the same carbon atom; m is the mole percentage of propylene glycol in the ethylene/propylene glycol copolymer moiety or moieties; and n is the mole percentage of ethylene glycol in the ethylene/propylene glycol copolymer moiety or moieties, wherein the ratio n: m is in the range from 35:65 to 80: 20; each glycol copolymer compound having a number average molecular weight in the range of 2000-10000; and 2) 3 to 15 % by weight of a fumed silica gel former; said balancing compositions being visco- elastic and having a Storage Modulus (G') between 1500 Pa and 5000 Pa at 22 °C, a Loss Modulus (G") smaller than the Storage Modulus up to a Cross Over

Frequency of 10-40 Hz, and a Critical Yield Stress exceeding 2 Pa.

The thixotropic balancing substance 230 may be a composition for balancing a rotary system disclosed in international patent application no. WO 2011/042549, which is hereby incorporated by reference in its entirety, comprising an amount of a thixotropic balancing substance; characterized by an amount of hydrophobic particles or nanoparticles distributed in said amount of said thixotropic balancing substance.

The thixotropic balancing substance 230 may comprise a plurality of balls. The balls may comprise metal, such as steel, titanium, copper or aluminium, composite material, such as aluminiumoxide or ceramics, or plastics. The balls may be polished or coated, for example polytetrafluoroethylene- (PTFE)- coated. The balls may have a diameter between approximately 1 mm and approximately 50 mm, for example approximately 15 mm.

Fig. 11 shows a cross-sectional view of a juicer, that is a juice centrifuge 300, according to an embodiment of the invention under test. The juice centrifuge 300 comprises a rotary system vertically housed in an approximately round

housing 110 comprising feet 115. In the test, the rotary system comprising motor 120 comprising stator 122 and rotor 124, shaft 130, bearings 135, container 140 situated above and separated from the motor 120, and comprising a cutting disc 142 and a locking device 144 has been modified according to the preferred embodiment of the invention. As shown in Fig. 11, the modified juice centrifuge 300 comprises a supplemental rotational element 200, that is adapter, attached to the container 140 above the cutting disc 142. The supplemental rotational element 200 corresponds with the closed rotational element 200, 204 shown in Fig. 5 and has been made from transparent polymethyl methacrylate (PMMA, poly methyl 2-methylpropenoate, acrylic glass, for example Plexiglas). The supplemental rotational element 200 has an outer diameter of 170 mm, an inner diameter of 130 mm, a height of 26.7 mm and a weight of 133 g. Its chamber 210 has been filled with 15 g of a thixotropic balancing substance 230 comprising 93 % by weight glycol polyethers, 4 % by weight fumed silica former and 3 % by weight polytetrafluoroethylene (PTFE) nanoparticles in accordance with the above-mentioned international patent application nos

PCT/EP2009/065058 and PCT/EP2010/065125. Experimental data has been taken with a make Crossbow (www.xbow.com^'), model CAL10HF3 triaxial acceleration sensor module 190 attached to a side of the housing 110 near the container 140 as shown in Fig. 11, such that its y-axis is oriented along the shaft 130, that is vertically, its x-axis is horizontally oriented perpendicularly to the shaft 130, that is in radial direction, and its z-axis is axis is horizontally oriented perpendicularly to the shaft 130 and the x-axis. Further, in order to add an imbalance, a steel bolt (not shown) having a weight of 6 g has been loosly placed in the

container 140.

With reference to Fig. 11, Fig. 12 shows an exemplary representation of deflections (d_x, d_y and d_z) in x-axis, y-axis and z-axis, respectively, in

millimeter (mm) of the original juicer 300 over time (t) in seconds (s), that is without supplemental rotational element 200 and thixotropic balancing

substance 230. The representation derives from experimental data taken at a rate of about 2 1/s and covers a period of about 70 s. After the original juicer 300 has been switched on, the deflections d_y in the y-axis increase to about 1.5 mm, the deflections d_z in the z-axis increase to about 3.7 mm, and the deflections d_x in the x-axis increase to about 4.6 mm. Changes of the deflections are about 1 mm. After the juicer 300 has been switched off at t = 18 s, the deflections decrease from t = 18 s to t = 40 s and tail off from t = 40 to t = 70 s. Briefly increasing deflections after switching off are caused by resonances of the juicer 300 during speeding down.

With reference to Fig. 11, Fig. 13 shows an exemplary representation of deflections (d_x, d_y and d_z) in x-axis, y-axis and z-axis, respectively, in

millimeter (mm) of the modified juicer 300 over time (t) in seconds (s), that is with supplemental rotational element 200, and without thixotropic balancing substance 230. The representation derives from experimental data taken at a rate of about 2 1/s and covers a period of about 115 s. After the modified juicer 300 initially without thixotropic balancing substance 230 has been switched on, the deflections d_y in the y-axis increase to about 1.2 mm, the deflections d_z in the z-axis increase to about 2.8 mm, and the deflections d_x in the x-axis increase to about 2.7 mm. Changes of the deflections are less than 1 mm. After the juicer 300 has been switched off at t = 38 s, the deflections decrease from t =38 s to t = 80 s and tail off from t = 80 to t = 115 s. Briefly increasing deflections after switching off are caused by resonances of the juicer 300 during speeding down.

A comparison of Figs 12 and 13 shows, that the supplemental rotational element 200 decreases vibration. This may be explained with the position of the supplemental rotational element 200 in the container 140. In some angle positions, the supplemental rotational element 200 compensates a portion of the vibration. Further, the weight of the container 140 is increased by the weight of the supplemental rotational element 200.

With reference to Fig . 11, Fig. 14 shows an exemplary representation of deflections (d_x, d_y and d_z) in x-axis, y-axis and z-axis, respectively, in

millimeter (mm) of the modified juicer 300 over time (t) in seconds (s), that is with supplemental rotational element 200 and added imbalance, and without thixotropic balancing substance 230. The representation derives from

experimental data taken at a rate of about 2 1/s and covers a period of about 120 s. After the modified juicer 300 without thixotropic balancing substance 230 has been switched on, the deflections d_y in the y-axis increase to about 10 mm, the deflections d_z in the z-axis increase to about 16 mm, and the deflections d_x in the x-axis increase to about 14 mm. After the juicer 300 has been switched off, the deflections decrease from t =25 s to t = 90 s and tail off from t = 90 to t = 120 s. Briefly increasing deflections after switching off are caused by resonances of the juicer 300 during speeding down.

A comparison of Fig. 14 with Figs 12 and 13 shows, that the deflections increase about five-fold and about six-fold, respectively.

With reference to Fig . 11, Fig. 15 shows an exemplary representation of deflections (d_x, d_y and d_z) in x-axis, y-axis and z-axis, respectively, in

millimeter (mm) of the modified juicer 300 over time (t) in seconds (s), that is with supplemental rotational element 200 comprising an amount of the thixotropic balancing substance 230 and added imbalance. The representation derives from experimental data taken at a rate of about 2 1/s and covers a period of about 117 s. After the modified juicer 300 with supplemental rotational element 200 comprising an amount of the thixotropic balancing substance 230 and the added imbalance has been switched on, the deflections d_y in the y-axis increase to about 4.5 mm, the deflections d_z in the z-axis increase to about 13.5 mm, and the deflections d_x in the x-axis increase to about 11 mm. Changes of the deflections decrease over time. At t =27 s, the thixotropic balancing substance 230 has distributed itself along the circumferential balancing area 210 such that the vibration is minimized, and the changes of the deflections approach zero. After the juicer 300 has been switched off, the deflections decrease from t =28 s to t = 90 s and tail off from t = 90 to t = 117 s. Briefly increasing deflections after switching off are caused by resonances of the juicer 300 during speeding down.

A comparison of Figs 14 and 15 shows, that, in general, the deflections comprise less changes, and that the deflections d_y in the y-axis are decreased by about 2.5 mm, the deflections d_z in the z-axis are decreased by about 1 mm, and the deflections d_x in the x-axis are decreased by about 2 mm. Thus, the supplemental rotational element 200 comprising an amount of the thixotropic balancing substance 230 according to an embodiment of the invention reduces, to a substantial degree, vibration in the rotary system of the juice centrifuge 300.

Fig. 16 shows a cross-sectional view of an angle grinder 400 according to an embodiment of the invention under test. The angle grinder 400 comprises a rotary system housed in a multi-sectional housing 110 comprising a handle section comprising a power cord 182 having a length of 4 m and switch 184, motor section, gear-box section and a protective shield 116. In the test, the rotary system comprising motor 120 comprising stator 122 and rotor 124, shaft 130, bearing 135, gear box 150 perpendicularly deflecting the shaft 130, a grinding disc or grinding wheel 146 having a diameter of 230 mm and being partially housed in the protective shield 116 and a locking device 144 having M14 thread has been modified according to the preferred embodiment of the invention. The angle grinder 400 is a make KRESS-elektrik GmbH & Co. KG, model

2600 WSB/1 230 angle grinder having a weight of approximately 6.5 Kg and comprising an original equipment manufacturer (OEM) balancing unit as

attachment. The OEM balancing unit comprises a rotational element comprising five steel balls having a diameter of 10 mm and oil. As shown in Fig. 16, the modified angle grinder 400 comprises a supplemental rotational element 200, that is adapter, attached to the shaft 130 between the protective shield 116 and the grinding disc 146. The supplemental rotational element 200 corresponds with the closed rotational element 200, 204 shown in Fig. 5 and has been made from steel. The supplemental rotational element 200 has an outer diameter of 62 mm, a conical inner diameter from 15.07 mm to 16.07 mm, a height of 19.2 mm and a weight of 238 g. Its chamber 210 has been filled with 10 g of a thixotropic balancing substance 230 comprising 93 % by weight glycol polyethers, 4 % by weight fumed silica former and 3 % by weight polytetrafluoroethylene (PTFE) nanoparticles in accordance with the above-mentioned international patent application nos PCT/EP2009/065058 and PCT/EP2010/065125. For the test, the angle grinder 400 has been situated on a cushion (not shown) and fixed to the ground using tension belts (not shown). Experimental data has been taken with a make Crossbow (www.xbow.com), model CAL10HF3 triaxial acceleration sensor module 190 attached to a side the motor section as shown in Fig. 16, such that its z-axis is oriented along the shaft 130 driving the grinding disc 146, that is vertically, its y-axis is oriented along to the housing 110, and its x-axis is axis is oriented perpendicularly to the shaft 130 and the y-axis.

With reference to Fig. 16, Fig. 17 shows an exemplary representation of deflections (d_x, d_y and d_z) in x-axis, y-axis and z-axis, respectively, in

millimeter (mm) of the original angle grinder 400 over time (t) in seconds (s), that is without the OEM balancing unit or supplemental rotational element 200 and thixotropic balancing substance 230, and without grinding disc 146. The representation derives from experimental data taken at a rate of about 2 1/s and covers a period of about 43 s. After the original angle grinder 400 has been switched on, the deflections d_y in the y-axis increase to about 5.5 mm, the deflections d_z in the z-axis increase to about 11 mm, and the deflections d_x in the x-axis increase to about 40 mm. The deflections d_x in the x-axis, that is around the y-axis, are caused by rotary movement from an angular momentum.

Thereafter, the deflections d_y in the y-axis decrease to about 0.5 mm, the deflections d_z in the z-axis decrease to about 2 mm, and the deflections d_x in the x-axis decrease to about 3 mm. After the angle grinder 400 has been switched off at t = 30 s, the deflections decrease from t =30 s to t = 40 s and tail off from t = 40 to t = 43 s. Briefly increasing deflections after switching off are caused by resonances of the original angle grinder 400 during speeding down. With reference to Fig. 16, Fig. 18 shows an exemplary representation of deflections (d_x, d_y and d_z) in x-axis, y-axis and z-axis, respectively, in

millimeter (mm) of the original angle grinder 400 over time (t) in seconds (s), that is with the OEM balancing unit, and with grinding disc 146. The

representation derives from experimental data taken at a rate of about 2 1/s and covers a period of about 46 s. After the original angle grinder 400 with the OEM balancing unit has been switched on, the deflections d_y in the y-axis increase to about 7.5 mm, the deflections d_z in the z-axis increase to about 8.5 mm, and the deflections d_x in the x-axis increase to about 44 mm. Changes of the deflections are about 4 mm. After the angle grinder 400 has been switched off at t = 30 s, the deflections decrease from t =30 s to t = 40 s and tail off from t = 40 to t = 46 s. Briefly increasing deflections after switching off are caused by

resonances of the angle grinder 400 during speeding down.

A comparison of Figs 17 and 18 shows, that, in general, the deflections are increased and comprise more changes. This may be explained with the presence of the grinding disc 146.

With reference to Fig. 16, Fig. 19 shows an exemplary representation of deflections (d_x, d_y and d_z) in x-axis, y-axis and z-axis, respectively, in

millimeter (mm) of the modified angle grinder 400 over time (t) in seconds (s), that is with supplemental rotational element 200 comprising an amount of the thixotropic balancing substance 230, and with grinding disc 146. The

representation derives from experimental data taken at a rate of about 2 1/s and covers a period of about 43 s. After the modified angle grinder 400 with the supplemental rotational element 200 comprising an amount of the thixotropic balancing substance 230 has been switched on, the deflections d_y in the y-axis increase to about 5 mm, the deflections d_z in the z-axis increase to about 6 mm, and the deflections d_x in the x-axis increase to about 45 mm. The deflections d_x in the x-axis, that is around the y-axis, are caused by rotary movement from an angular momentum. Thereafter, the deflections d_y in the y-axis decrease to about 4 mm, the deflections d_z in the z-axis decrease to about 4 mm, and the

deflections d_x in the x-axis decrease to about 2 mm. After the angle grinder 400 has been switched off at t = 28 s, the deflections briefly increase from t =28 s to t = 31 s, decrease from t =31 s to t = 38 s and tail off from t = 38 to t = 43 s. Briefly increasing deflections after switching off are caused by resonances of the angle grinder 400 during speeding down.

A comparison of Figs 17 and 18 shows, that, in general, the deflections d_y and the deflections d_z are increased and comprise more changes owing to the presence of the grinding disc 146. However, despite to the presence of the grinding disc 146, the deflections d_x are similar, if not even reduced to a certain degree.

A comparison of Figs 18 and 19 shows, that, the deflections d_y, deflections d_z and deflections d_x are substantially reduced and comprise less changes owing to the presence of the thixotropic balancing substance 230. In more detail, the average deflections d_y are reduced from about 5 mm to about 4 mm and the

corresponding changes are reduced from about 2 mm to less than 1 mm, the average deflections d_z are reduced from about 7.5 mm to about 4 mm and the corresponding changes are reduced from about 3 mm to about 2 mm, and the average deflections d_x are reduced from about 6 mm to about 2 mm and the corresponding changes are reduced from about 3 mm to about 1 mm. Thus, the supplemental rotational element 200 comprising an amount of the thixotropic balancing substance 230 according to an embodiment of the invention reduces, to a substantial degree, vibration in the rotary system of the angle grinder 300.

Fig. 20 shows a cross-sectional view of an injection-moulding machine 500 according to an embodiment of the invention. The injection-moulding

machine 500 comprises a motor 120, a first end support 530, and a second end support 540 spaced apart from the first end support and serving as a fixed work- holding attachment 540, on a machine base or machine bed 520. The injection- moulding machine 500 further comprises a tooling unit 140 being slidably movable between the first end support 530 and the second end support 540 with bearings 148, for example bush bearings, plan bearings or sliding bearings, on one, two, three, four or more rods 550, and serving as free work-holding attachment. Thus, parts of an injection die (not shown) may be attached to the fixed work-holding attachment 540 and the free work-holding attachment 140. The free work-holding attachment 140 may be moved towards the fixed work- holding attachment 540 for injection-moulding an item in the injection die in a closed position, and, thereafter, the free work-holding attachment 140 may be moved away from the fixed work-holding attachment 540 for releasing the injection-moulded item from the injection die in an opened position. The injection-moulding machine 500 further comprises a rotary system for driving the free work-holding attachment 140, that may be horizontally arranged as indicated in Fig. 20. The rotary system comprises motor 120 comprising stator 122 and rotor 124 and shaft 130. The shaft 130 may be connected to the free work- holding attachment 140. The rotor 124 may comprise a first gear 152 having an inner thread, and the shaft 130 may comprise a second gear 154 having an outer thread meshing with the inner thread, such that turning the rotor 124 in a first direction drives the free work-holding attachment 140 towards the fixed work- holding attachment 540, and turning the rotor 124 in a second direction opposite to the first direction drives the free work-holding attachment 140 away from the fixed work-holding attachment 540. The rotary system may further comprise a bearing 138, that may be situated in the first end support 530. According to the preferred embodiment of the invention, the rotor 124 further comprises a supplemental rotational element 200 for reducing vibration when driving the free work-holding attachment 140.

In another injection-moulding machine 500, the shaft 130 may be rotatable. Thus, the shaft 130 may be coupled to the free work-holding attachment 140 via a bearing (not shown), and the rotor 124 may be connected to the shaft 130 and comprise a first gear (not shown) having an outer thread, and the stator 122 may comprise a second gear (not shown) having an inner thread meshing with the inner thread, such that turning the rotor 124 and shaft 130 in a first direction drives the free work-holding attachment 140 towards the fixed work-holding attachment 540, and turning the rotor 124 and shaft 130 in a second direction opposite to the first direction drives the free work-holding attachment 140 away from the fixed work-holding attachment 540. In the injection-moulding machine 500, wherein the shaft 130 is rotated, the shaft 130 may comprise a supplemental rotational element 200 for reducing vibration when driving the free work-holding attachment 140. The supplemental rotational elements 200 may, for example, correspond with the closed rotational element 200, 204 shown in Figs 5, 8 or 9. In the injection-moulding machine 500, wherein the shaft 130 is rotated, the shaft 130 may, alternatively or additionally, comprise be the rotational element 200, 204, 206 shown in Figs 4-10 for reducing vibration. In an injection-moulding machine 500, wherein a pump for conveying injection- moulding material comprises a rotary system, the rotary system may comprise a rotational element 200, 204, 206 for reducing vibration.

In a tooling machine such as an injection-moulding machine 500, comprising a door or lid for shielding comprises a rotary system, the rotary system may comprise a rotational element 200, 204, 206 for reducing vibration.

Embodiments of the inventions comprise a corresponding apparatus that may carry out the method.

Embodiments of the inventions comprise a corresponding system that may carry out the method, possibly across a number of devices.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art, that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown. It is to be understood, that the above description is intended to be illustrative and not restrictive. This application is intended to cover any adaptations or variations of the invention. Combinations of the above embodiments and many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. The scope of the invention includes any other embodiments and applications in which the above structures and methods may be used. The scope of the invention is, therefore, defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A method of reducing vibration in a rotary system (120, 130, 140, 150) of a tool (100; 300; 400; 500), comprising :

balancing said rotary system (120, 130, 140, 150),

characterized by

providing a rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200) comprising a chamber (210) having a fulcrum on a rotational axis (240) of said rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200), comprising a circumferential balancing

area (220) and being partially filled with an amount of a thixotropic balancing substance (230).

2. The method of claim 1, wherein the tool is a hand-held tool.

3. The method of claim 1 or 2, wherein the tool is a machine tool, a grinder, a mixer, a stand mixer, power chopper or meat mincing machine, that is meat chopper, blender such as a hand blender or immersion blender, food processor, food slicer, a juicer, a power juicer or juice centrifuge, a grinder, an angular grinder, sander, polisher, saw, a circular hand saw, drilling machine or boring machine, a power drill, that is an electric drill or a cordless drill, percussion drilling machine, a hammer drilling machine, a pneumatic hammer drilling machine, power screwdriver, an electric screwdriver or a cordless screwdriver, drywall screwdriver, a power planer, an electric planer, a mowing machine, a lawn- mower, an agricultural machine or farm machine, a harvester, an injection- moulding machine, or a combination thereof.

4. The method of claim 1, further comprising :

rotating said rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200) about the rotational axis (240), such that said thixotropic balancing substance (230) liquefies and distributes itself along the circumferential balancing area (220), and an imbalance of said rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200) is reduced.

5. The method of any one of the claims 1-4, wherein : said rotational axis (240) is oriented horizontally; or

said rotational axis (240) is oriented vertically.

6. The method of any one of the claims 1-5, wherein :

- said rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200) is an original element of said rotary system (120, 130, 140, 150), a replacement element of said rotary system (120, 130, 140, 150), or a

supplemental element to said rotary system (120, 130, 140, 150);

said rotational element (130, 152) is a hollow shaft or tubular shaft;

- said rotational element (130, 152) is an articulated shaft, for example a cardan shaft; or

a combination thereof.

7. The method of claim 6, wherein:

- the supplemental element is disc-shaped; or

the supplemental element is ring-shaped.

8. The method of any one of the claims 1-7, wherein :

said rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200) is a shaft (130, 152);

said rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200) is a rotor (124) of said tool (100; 300; 400; 500);

said rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200) is a gear wheel;

- said rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200) is a bearing (135; 145); or

a combination thereof.

9. The method of any one of the claims 1-8, wherein :

- said chamber (210) is annular or ring-shaped, or cylindrical;

said chamber (210) has a cross section being rectangular, square, semicircle-shaped, bell-shaped or circular;

said chamber (210) has a diameter of between 0.005 m and 2 m, or between 0.01 m and 1 m, or between 0.02 m and 0.5 m, or between 0.05 m and 0.2 m, or 0.1 m; said chamber (210) has a length of between 0.01 m and 1 m, or between 0.02 m and 0.5 m, or between 0.05 m and 0.2 m, or 0.1 m; or

a combination thereof.

10. The method of any one of the claims 1-9, wherein :

said amount of said thixotropic balancing substance (230) is between 0.001 kg and 1000 kg, or between 0.002 kg and 500 kg, or between 0.005 kg and 200 kg, or between 0.01 kg and 100 kg, or between 0.02 kg and 50 kg, or between 0.05 kg and 20 kg, or between 0.1 kg and 10 kg, or between 0.2 kg and 5 kg, or between 0.5 kg and 2 kg, or 1 kg;

said chamber (210) is filled with the amount of said thixotropic balancing substance (230) to between 1 % and 90 %, or between 10 % and 80 %, or between 25 % and 75 %, or 50 %; or

a combination thereof.

11. An apparatus for reducing vibration in a rotary system (120, 130, 140, 150) of a tool (100; 300; 400; 500), characterized by:

a rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200) comprising a chamber (210) having a fulcrum on a rotational axis (240) of said rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200), comprising a circumferential balancing area (220) and being partially filled with an amount of a thixotropic balancing substance (230).

12. The apparatus of claim 11, wherein the tool is a hand-held tool.

13. The apparatus of claim 11 or 12, wherein the tool is a machine tool, a grinder, a mixer, a stand mixer, power chopper or meat mincing machine, that is meat chopper, blender such as a hand blender or immersion blender, food processor, food slicer, a juicer, a power juicer or juice centrifuge, a grinder, an angular grinder, sander, polisher, saw, a circular hand saw, drilling machine or boring machine, a power drill, that is an electric drill or a cordless drill, percussion drilling machine, a hammer drilling machine, a pneumatic hammer drilling machine, power screwdriver, an electric screwdriver or a cordless screwdriver, drywall screwdriver, a power planer, an electric planer, a mowing machine, a lawn-mower, an agricultural machine or farm machine, a harvester, an injection- moulding machine, or a combination thereof.

14. A rotary system (120, 130, 140, 150) of a tool (100; 300; 400; 500), for reducing vibration in said rotary system (120, 130, 140, 150), characterized by: a rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200) comprising a chamber (210) having a fulcrum on a rotational axis (240) of said rotational element (120, 124, 130, 135, 140, 142, 144, 145, 150, 152, 154; 200), comprising a circumferential balancing area (220) and being partially filled with an amount of a thixotropic balancing substance (230).

15. The rotary system of claim 14, wherein the tool is a hand-held tool.

16. The rotary system of claim 14 or 15, wherein the tool is a machine tool, a grinder, a mixer, a stand mixer, power chopper or meat mincing machine, that is meat chopper, blender such as a hand blender or immersion blender, food processor, food slicer, a juicer, a power juicer or juice centrifuge, a grinder, an angular grinder, sander, polisher, saw, a circular hand saw, drilling machine or boring machine, a power drill, that is an electric drill or a cordless drill, percussion drilling machine, a hammer drilling machine, a pneumatic hammer drilling machine, power screwdriver, an electric screwdriver or a cordless screwdriver, drywall screwdriver, a power planer, an electric planer, a mowing machine, a lawn-mower, an agricultural machine or farm machine, a harvester, an injection- moulding machine, or a combination thereof.