Title of Invention

SPINDLE FOR A MACHINE TOOL WITH A BEARING ELEMENT WITH A CAPILLARY INLET FOR FEEDING OF LUBRICANT

Abstract

EN) The invention relates to a spindle (1) for a machine-tool, especially an engine spindle, comprising a housing (6) for receiving an electric engine, a shaft received in bearing elements (2, 3, 4, 5) and driven by the electric engine, and especially a tool receiving element for a tool for machining workpieces, at least one bearing element (2, 3, 4, 5) comprising a capillary feeding line (15, 16, 17, 18) for supplying lubricant by means of a pump element (20). The invention also relates to a bearing element (2, 3, 4, 5) for one such spindle (1), said bearing element comprising at least one recess (11, 12, 13, 14) for receiving a capillary feeding line (15, 16, 17, 18) for supplying lubricant by means of a pump element (20). The invention further relates to a method for operating one such spindle for a machine-tool, whereby a temporal and/or quantitative dosing of lubricant is carried out according to the evaluation of a sensor element, in order to sufficiently lubricate at least one bearing element.

Full Text

Spindle for a Machine Tool with a bearing element with a Capillary Inlet for feeding of lubricant Description: The Invention relates to a spindle for a machine tool with the properties of the generic description of the Patent Claim 1. Further the Invention relates to a bearing element for such a spindle and a process for operating such a spindle. As the state-of-the-art of technology, it is already known for quite some time about conventional oil-air lubrication for feeding of oil as lubricant to the bearing elements of spindles for machine tools. In such oil-air-lubrication, oil quantities are fed in specific intervals in an impulse type fashion, whereby the oil quantities fed should not be below a certain minimum quantity. The Invention is focused on the task to offer a spindle for a machine tool, in which a bearing element can be supplied uniformly with minimum quantities of lubricant. Further, a bearing element and a process should be offered for operating such a spindle. This task is resolved for the spindle through the properties of distinguishing part of the patent claim 1 in conjunction with the properties of the generic description. Advantages Design Form of the Spindle are described in the sub-claims 2-7. For the bearing element, this task is resolved through the properties of the distinguishing part of the patent claim 8 in conjunction with the properties of the generic description. For the process the objective is achieved through the characteristics of the distinguishing part of the patent claim 9 in conjunction with the characteristics of the generic description. In respect of the invention based spindle, oil is fed as lubricant through minimum one capillary inlet to at least one of the bearing elements. In contrast to the known oil-air-lubrication, transport of the oil does not happen through an air stream/ glow but within the capillary inlets (capillary hose or tube), which is always filled with oil, such that in the case of an enhanced feed, an immediate reaction and oil supply at the place of requirement takes place without any delay because of the available capillary inlets, that is at the end of the respective capillary inlet. A uniform lubrication of even smallest quantities of especially 10-100 jil/h (micro litre per hour) is enabled. The capillary inlets have typically an open dia of less than 2/10 mm, whereby inlets in accordance with the customary oil-air-lubrication have an opening dia of typically minimum 2 mm. Advantageously the capillary inlet is seated in a recess (bore) in the inner or outer ring of the bearing element (for instance, a roller bearing, radial beveled ball bearing) and the lubricant is directly fed to the roller contact without air as the transport medium. As a result, in contrast to the customary oil-air-lubrication, the bearing cannot be blown dry. In an alternative design form, the oil is almost immediately fed to the bearing element through the capillary inlet, and a last path to the bearing element is surmounted by feeding of air through carrying of oil at the end of the capillary inlet. In an advantageous design, the pump element for instance is designed as a micro toothed ring pump or as micro valve (for instance, in the form of Piezoactors). The pump element in an ideal design form is connected with a distribution element, from which several capillary inlets branch out. As a result, a reliable spreading of the lubricant for several bearing elements in the spindle is made possible. The flow resistance of a capillary is proportional to 4 x potency of the open dia (Law of Hagen-Poiseuille). By means of an additional capillary, bypass the oil quantity fed can be decreased to lesser percentage of the nominal volume flow of the pump element, because the oil quantity conveyed from the pump element is divided in the ratio of the flow resistance of inlet capillaries and bypass capillaries. As a result, the pump element can operate in an advantageous work range. The capillaries can be realized in an integrated manner as part of the oil field or as capillary jets in the pump element, (for instance, as micro system technically manufactured Maender (or such similar item. In an alternative design form, the pump element can be so designed, for instance, through correspondingly defined leakage flows or defined split geometries, that the properties of the bypass can be realized through the pump characteristic itself. Through a filter element in bypass, the cleanliness of the lubricant can be enhanced permanently in the subsidiary flow. The oil quantity conveyed from the pump element is divided in the ratio of the cross section of the inlet capillary(s) and bypass capillary. Based on an advantageous design form, the pump element, the distributor element and additional elements can be integrated in a space saving fashion in the housing of the spindle. The invention-based bearing element possesses at least a recess for seating a capillary inlet for feeding of lubricants through a pump element. Such bearing elements can be used for a spindle designed as described and can also be used for jointing with capillary inlets for feeding of lubricant for lubricating the bearing heads and the bearing. In the invention-based process for operating the spindle, a time based and/or quantity based dosage of lubricants for adequate lubrication for at least one of the bearing elements is carried out through an evaluation of the sensor element. The invention is further explained on the basis of design examples in the drawings. The drawings show: Figure 1: A schematic totality of the spindle for capillary inlets for feeding of lubricants. Figure 2 A first design form of bearing elements in a spindle as per figure 1 Figure 3 A further design form of bearing elements of a spindle as per figure 1, as well as Figure 4: A control circuit for requirement-based lubricant dosage. Figure 1 shows a schematically illustrated spindle 1 for a machine tool (machining spindle) with a shaft placed in bearing elements 2, 3, 4 and 5, located in a housing 6 of the spindle 1. The outer rings 7,8, 9 and 10 of the bearing elements 2, 3, 4 and 5 possess recesses 11, 12, 13 and 14 (Bores) for seating of capillary inlets 15, 16, 17 and 18 illustrated schematically and therefore in an enlarged fashion, which for instance are designed as capillary hoses known by themselves. Totally 4 capillary inlets, 15, 16, 17 and 18 are illustrated which are jointed with a pump element 20 through a distributor 19. The distributor 19 can have further capillary jets 42, 43, 44 and 45 and possesses one more capillary line 21, namely a bypass, which can also have a capillary jet. The capillary jets can be individually adjustable and could serve the purpose of dosaging the transported quantity flows in the individual capillary inlets and in bypass. The pump element 20 transport lubricant, for instance, oil from a storage container 22, and feeds the conveyed lubricant to the four capillaries 15, 16, 17 and 18. A part of the lubricant is deflected through the additional capillary line 21 and returned to the storage container 22, where applicable after being filtered. Figure 2 shows an arrangement possibility of bearing elements 23 and 24 immediately side by side in a housing 6 of a spindle 1 as per figure 1. The outer rings 25 and 26 of the bearing element 23 and 24 have recesses 27, and 28 for seating of capillary lines 29 and 30 schematically illustrated. Figure 3 shows an additional design form in which the bearing elements 31 and 32 are seated with a distance from each other in housing 6 of a spindle 1. Between the bearing elements 31 and 32, a distributor element 33 is provided in which capillary inlets 34 and 35 converge. These capillary inlets 34 and 35 end at the end points 36 and 37 and are connected through connection channels 38 and 39 sideways with the bearing elements 31 and 32. A feeding of air takes place through a bore 40 and oil in the end areas 36 and 37 of the capillary inlets 34 and 35 collected and fed through the connection channels 38 and 39 to the bearing elements 31 and 32. A self explanatory control cirbuit as illustrated in figure 4, enables a requirement-based regulation of the lubrication. Using sensor elements, operating parameters of the working spindle 1 (for instance, RPM, Motor Temperature, Coolant Temperature, Bearing Temperature) can be compiled and using well known inter-relationships, the strength of a lubricant foil/coating in the existing bearing elements can be estimated. In the event that here a value is below the limit value, the lubrication regulator can be fed with an enhanced lubricant quantity through the dosing element, as a result of which the spindle bearing receives an additional coating of the lubricant and thus remains adequately lubricated. The dosing of the lubricant quantities and therewith the modification of the activity of the pump element can take place for instance according to the following strategies: - With fixed values for the entire machine operation time as a factor of the type of spindle bearing design etc. (comparable with hitherto adopted lubrication processes) or - Controlled on the basis of characteristic fields for instance oil quantity = f (RPM of the spindle) or - Regulation on the basis of a direct measurement of the lubricant coating on the bearing (at the moment, no reliable process is available) - Regulation on the basis of an estimate of the thickness of the lubricant coating with the help of parameters which are simple to measure (bearing temperature etc.) All strategies can be used individually or combined. The estimated thickness of the lubrication coating can serve as the regulating parameter, as the setting parameter for the lubricant quantity. Reference Glossary 1 Spindle 2,3,4,5 Bearing Element 6 Housing 7,8,9,10 Outer ring 11,12,13,14 Recess 15,16,17,18 Capillary Inlet 19 Distributor 20 Pump Element 21 Capillary Inlet 22 Storage Container 23,24 Bearing Element 25,26 Outer Ring 27,28 Recess 29,30 Capillary Inlet 31,32 Bearing Element 33 Distributor Element 34,35 Capillary Inlet 36,37 End Points 38,39 Jointing Channel 40 Bore 41 Shaft 42,43,44,45,46 Jet Patent Claims 1. Spindle for a machine tool, especially motor spindle, with a housing for seating an electro motor and a shaft capable of being driven by the electro motor and placed in the bearing element, especially with a tool seating for a tool for work piece machine is thereby characterized, that minimum one bearing element (2,3,4,5) has a capillary inlet (15,16,17,18) for feeding of lubricant through a pump element (20). 2. Spindle according to Claim 1 is thereby characterized, that the bearing element (2,3,4,5) has a recess (11,12,13,14) in the outer or inner ring for seating the capillary inlet (15,16,17,18). 3. Spindle according to Claim 1 or 2 is thereby characterized, that several capillary inlets (15,16,17,18) are visualized which are connected with the pump element (20) through a distributor element (19). 4. Spindle according to Claim 3 is thereby characterized, that the distributor element (19) has an additional capillary inlet (21) as bypass. 5. Spindle according to one of the above claims, is thereby characterized, that the spindle (1) has two bearing elements (2,3,4,5) adjacently arranged with a capillary inlet each (15,16,17,18). 6. Spindle according one of the above claims, is thereby characterized, that the spindle (1) has two bearing elements (2,3,4,5) arranged adjacent and at a distance to each other with a capillary inlet (15,16,17,18) 7. Spindle according to one of the above claims, is thereby characterized, that the bore (40) for feeding of air is meant for compiling information on the lubricant flowing from a capillary inlet (15,16,17,18) 8. Bearing element for a spindle for a machine tool especially for a spindle according to one of the Claims 1 to 7, is thereby characterized, that the bearing element (2,3,4,5) has at least one recess (11,12,13,14) for locating a capillary element (15,16,17,18) for feeding of lubricants through a pump element (20). 9. Process for operating a spindle for a machine tool especially a spindle according to one of the claims 1 to 7, is thereby characterized, that a time based and/or quantity-specific dosing of lubricant for ensuring adequate lubrication for at least one bearing element takes place through use of a control circuit. Dated this 21 day of September 2006

Documents:

3470-CHENP-2006 CORRESPONDENCE OTHERS 08-11-2012.pdf

3470-CHENP-2006 FORM-3 08-11-2012.pdf

3470-CHENP-2006 AMENDED CLAIMS 08-11-2012.pdf

3470-CHENP-2006 AMENDED CLAIMS 20-06-2012.pdf

3470-CHENP-2006 CORRESPONDENCE OTHERS 04-01-2012.pdf

3470-CHENP-2006 CORRESPONDENCE OTHERS 04-07-2012.pdf

3470-CHENP-2006 EXAMINATION REPORT REPLY RECEIVED 20-06-2012.pdf

3470-CHENP-2006 FORM-3 20-06-2012.pdf

3470-CHENP-2006 OTHER PATENT DOCUMENT 20-06-2012.pdf

3470-CHENP-2006 POWER OF ATTORNEY 04-07-2012.pdf

3470-chenp-2006-abstract.pdf

3470-chenp-2006-claims.pdf

3470-chenp-2006-correspondnece-others.pdf

3470-chenp-2006-description(complete).pdf

3470-chenp-2006-drawings.pdf

3470-chenp-2006-form 1.pdf

3470-chenp-2006-form 3.pdf

3470-chenp-2006-form 5.pdf

3470-chenp-2006-pct.pdf