DE3338075A1 - Bearing with hydrostatic load compensation, preferably for a plurality of table guideways arranged one above the other - Google Patents

Abstract

Bearing with hydrostatic load compensation, preferably for a plurality of table guideways arranged one above the other. Pressure medium is fed to the bearing gap of the table guideway via restrictors by a pressure generator and the pressure in the feed to the restrictors is controlled as a function of the loading of the table guideway. The aim is optimum control of the bearing-gap size when there are changes in static and dynamic load and viscosity, including the case of table guideways arranged one above the other. The object is, by means of an optimisable control structure, to enable the accuracy of bearing-gap constancy during load changes to be influenced and the size of the bearing gap to be changed and to achieve partial interlinking in terms of control in the case of a plurality of table guideways. According to the invention, the pressure prevailing in the bearing gap of one table guideway is used to form a pressure set point by electronic means, the same set point applying even when there is a plurality of table guideways. This pressure set point is, after evaluation of its sign, summed with an actual pressure value formed from the pressure prevailing upstream of the restrictors and a control variable analogous to the viscosity. The deviation obtained is amplified and used to drive an actuator which, in a bypass line, diverts part of the delivery flow in order to maintain the actual pressure. <IMAGE>

Description

Hydrostatically load-compensated storage, preferably

several table guides arranged one above the other The invention relates to a hydrostatic load-compensated bearing, preferably several on top of each other arranged table guides, with the bearing gap of the table guide via carrier bags a pressure flow is supplied from a pressure flow generator via throttle points and Depending on the load on the table guide, an assigned regulator regulates the pressure regulates the inlet to the throttle points, as well as other control technology means to eliminate the effects of changes in viscosity of the pressure medium on the Bearing gap size are provided.

Are hydrostatic load-compensated bearings of table guides well known. For example, from DE-OS 1 525 121 a work-related one Procedure of a hydrostatic bearing known, the bearing gap of a Delivery pump a flowing operating medium is supplied via throttle points, wherein the pressure of the Betriebsæittcls at the inlet to the throttle point in at least approximately constant, predetermined ratio to the one depending on the bearing load changing pressure is kept in the bearing gap. A partial flow of the equipment is thereby used branched off before the inlet to the throttle point, the size of the partial flow through a regulator according to the one acting at the inlet to the throttle point and in the bearing gap Pressures is set. The one to carry out this working procedure in DE-OS 1 525 121 described and shown control device has a Feed pump. which from a storage container operating medium via a supply line in which an adjustable throttle is arranged. feeds into the bearing gap.

Before and after the adjustable throttle are from the supply line a branch line and a pressure measuring line connected to a hydromechanical regulator. This controller has two interconnected and axially movable in a housing recorded pistons with different cross-sectional areas, on each other facing away from the end faces the pressures of the branch line and the pressure measuring line works. The ratio of the cross-sectional areas corresponds to the inverse ratio of pressures. The front edge of the smaller piston serves as the control edge in Connection to a control opening, to which one led to the storage container Return line is connected.

This control device suffers from several serious disadvantages afflicted, which have both economic and technical effects. So there is a major disadvantage in the use of the hydromechanical regulator, which is is a proportional controller with a large permanent control deviation. The reason for this is the small size given due to structural and dimensional considerations Circular strengthening.

Since with hydromechanical regulators the functional features and properties are already finalized with the construction, this controller is liable Another disadvantage is that an optimal design of the controller is only unjustifiable high effort empirically and for specific conditions is possible. This disadvantage leads back to the reason that the optimal design of the total gap size the viscosity of the operating medium, the pressure range, etc. depends on factors.

Another disadvantage is that this control device no influence on the constancy of the bearing gap size when the load regime changes The reason for this is that the given loop gain is not influenced of the control loop, but only through a constructive change (dimensionally) of the Controller is possible, Another disadvantage is the time-consuming and costly Adjustment of a changed bearing gap size.

The reason for this is the required controllable attitude of everyone individual throttle, which requires gap size measurements on the individual carrier bags are.

To partially limit the disadvantages shown, the DE-OS 1 525 121 is supplemented by DE-OS 1 575 464. Aim of this supplement is the constancy of the bearing gap size under changing conditions Influencing variables such as deformations of the bearing or changes in viscosity of Resources. The working procedure is based on the fact that the intermediate pressure in the bearing gap between two defined, adjacent measuring sections the intermediate pressure between two nominal measuring sections connected in parallel to the measuring sections is compared, and that the difference between the two intermediate pressures is constantly on one constant value, preferably to zero, is adjusted. The ones to carry out this The device disclosed in the method provides that that of DE-OS 1 525 121 according to Throttle point is designed as an axial control slide, the control piston of which on both sides can be acted upon with the intermediate pressures of the measuring section or the target measuring section and due to a change in the difference in the intermediate pressures, the effective throttle length of the control piston is changed.

The disadvantage of the device according to DE-OS 1 575 464 is that with unacceptably high expenditure, only individual ones triggered by external influences Effects on the control device according to DE-OS 1 525 121 are reduced, however the regulatory disadvantages are not eliminated.

The reason why the thermally induced changes are only reduced, but could not be eliminated or corrected, lies in the design the throttle point with a function of a hydromechanical regulator. In order to are the disadvantages shown with respect to the controller of DE-OS 1 525 121 and their Causes fully transferable to the throttle point of DE-OS 1 575 464.

The invention has the purpose of providing a static under conditions and dynamic load changes and different viscosity and pressure values optimal regulation of the bearing gap size, also for several table guides arranged one above the other to be realized with little economic effort.

The invention is based on the object of a hydrostatically load-compensated Storage, preferably several table guides arranged one above the other, whereby the bearing gap of the table guide via carrier bags from a pressure current generator Throttle points a pressure flow is supplied and depending on the load an assigned to the table guide Regulator increases the pressure in the inlet regulates the throttling points, as well as other control-technical means for elimination the influence of changes in the viscosity of the pressure medium on the size of the bearing gap are provided to create, the accuracy through an optimizable control structure the constancy of the bearing gap can be influenced in the event of load changes and the size of the bearing gap without mechanical component change is changeable, as well as a direct inclusion of viscosity-dependent Corrections in the bearing gap control loop and a partial control system Chaining is possible with table guides arranged one above the other.

According to the invention the object is achieved in that of at least two between the throttle points and these zugeord.

Neten carrier bags running pressure lines of a table guide Secondary lines branched off and on the input side to an electronic single or Multiple setpoint generator modules are connected, the output side to a The input of a table guide-related summing element is connected to its further Input and output of a p-u converter is present, whose input-side secondary line from a table guide-related pressure line, in the direction of flow of the pressure medium is branched off in front of the assigned laminar fixed throttle, to at least one pressure medium temperature measuring point an electronic single or multiple temperature evaluation assembly is created and on the output side to another input of the table guide-related summing element is connected, the output of which is connected to a control amplifier and this with its output on an actuator in a bypass line of the table guide-related Main pressure line is switched.

An advantageous embodiment of the invention is that the Electronic single setpoint generator module on the input side of each secondary line has associated p-u converters, the outputs of which are switched to a summing element and its output is fed to a setpoint generator block, whose output is that of this module.

Another advantageous embodiment of the invention, preferably for several table guides arranged one above the other is that the electronic Multiple setpoint generator -Assembly on the input side of each Secondary line to one of several table guides or table guides arranged one above the other.

p-u transducers assigned by a guideway to a table guide owns whose outputs are connected to a summing element and this with his Output parallel to each of the table guides or table runners arranged one above the other.

Setpoint generator block belonging to the individual guideways of a table guide whose outputs are those of this module.

Another advantage of the invention is that the electronic Single temperature evaluation module with a temperature sensor on the input side T-u converter, which has its output on a correction value generator is switched and this is applied to an adapter whose output is the this temperature evaluation module is.

Depending on the application, one advantage of the invention is its further advantage Design in that the electronic multiple temperature evaluation module consists of a single temperature evaluation assembly, the output of the Correction value generator parallel to table guide or guide track related for a table guide is brought out and each switched to an adaptation link, the outputs of which are those of the multiple temperature evaluation module.

Another advantage of the invention is that the control amplifier is implemented by an operational amplifier that is fed back via a PID element. Another preferred embodiment of the invention provides that the correction value generator consists of an operational amplifier that is fed back via a correction element. Another advantage here is that the correction element consists of a non-linear one Network exists. It is preferably provided for the further embodiment that a motor-adjustable throttle is used as the actuator.

In other ways, however, it can also be advantageous that as an actuator a proportional valve is used.

In addition, the invention is more dynamic when taken into account Load changes have the advantage that each carrier bag has a control loop with carrier bag-related electronic Single setpoint generator module is assigned.

Finally, as an advantage of the embodiment according to the invention mention that as throttle points, laminar fixed throttles optimized for the table guide The invention is to be provided in more detail below using an exemplary embodiment explained. The accompanying drawing shows a schematic representation the inventive storage of two table guides arranged one above the other.

The selected embodiment shows a table guide track 1 of a Machine bed, a machine table which can be moved on the table guide track 1 2 and mounted on its table guide a rotary table 3, as it is for example is required for generating the rolling motion during gear machining. The table guide track 1 and the table guide of the machine table 2 are each with several carrier bags 4; 5 or 6; 7 provided. The one made up of several table guideways 1 existing table guide of the machine bed and the table guide of the machine table 2 is a pressure current generator 8 in relation to the table guide; 9 assigned which from a storage container 10 pressure medium via its main pressure lines 11; 12 as well from these branched pressure lines 13; 14; 15; 16 and 17, respectively; 18; 19; 20 in the carrier bags 4; 5 or 6; 7 promote. In each of the pressure lines 13; 14; 15; 16 and 17, respectively; 18; 19; 20 is a table guide-related laminar fixed throttle that is optimized in the same size 21; 22; 23; 24 or

25; 26; 27; 28 arranged. Of at least two pressure lines 14; 16 are a table guide, each between the laminar fixed throttle 22; 23 and the associated carrying case 4; 5, secondary lines 29; 30 branched off and to a Multiple setpoint generator module 31 connected. This multiple setpoint generator assembly 31 has at least two pressure-voltage converters on the input side, followed by p-u converters 32 33 denotes, at the inputs of which the secondary lines 29; 30 are present. The exits the p-u converter 32; 33 are connected to inputs of a summing element 34, the with its output parallel to table guidance-related setpoint generator modules 35; 36 is clamped, the outputs of which are the outputs of the multiple setpoint generator module 31 form and at each an input of a table guide-related Summing member 37; 38 are connected. Each of a pressure line 14; 17th each table guide is in front of the associated one in the direction of flow of the pressure medium laminar fixed throttle, a bypass 39; 40 branched off and to a p-u converter 41; 42 switched, the output of which is connected to a further input of the table guide-related Summing member 37; 38 is present. At a pressure medium temperature measuring point 43 is a electronic multiple temperature evaluation assembly 44 connected. This exists from a temperature-voltage- # andler, named after the following T-u-ttJandle r 45, the output of which is applied to a correction value generator 46. The correction value oiler 46 is made up of an operational amplifier which is fed back via a correction element 47 48 is formed, the correction element 47 consisting of a non-linear network. The output of the correction value generator 46 is parallel to the table guide Adjustment members 49; 50 switched, the outputs of which are those of the multiple temperature evaluation module 44 are and to further inputs of the assigned table guide-related summing elements 37; 38 are clamped. The table management related summaries 37; 38 are each with its output to a control amplifier 51; 52 connected, the control amplifier 51; 52 by a proportional-integral-differential element. below PID gate 53; 54 called, feedback operational amplifier 55; 56 realized is. The output of each variable gain amplifier 51; 52 is to an actuator 57 or 58 connected, each in a bypass line 59; 60 of the associated table guide-related Main pressure line 11; 12 is arranged.

As an actuator 57; 58 can be a motor-adjustable throttle as well as a proportional valve may be best suited on a case-by-case basis.

The application of the hydrostatic load-compensated bearing for a Individual table guidance requires instead of the multiple setpoint generator module 31 only a simple sol # worth building group, which differs in that the output of the summing element 34 is only switched to a setpoint generator module 35 and the single setpoint generator module therefore only has one output. The same applies to the multiple temperature evaluation module from which themselves the single temperature evaluation assembly applicable to a single table guide differs in that the output of the correction value generator 46 is only on Adaptation element 49 is connected and thus the simple temperature evaluation module also has only one exit.

The requirements of a load-compensated storage under the conditions dynamic load changes within a table guide are made using a described table guide-related control loop for each carrying bag of the table guide fulfilled with the bag-related single setpoint generator assembly.

The operation of the device according to the invention is as follows: The pressure flow generators 8; 9 via their main pressure lines 11; 12 and pressure lines 13; 14; 15; 16 and 17, respectively; 18; 19; 20 in the carrier bags assigned to the table guide 4; 5 or 6; 7 conveyed pressure flow experiences through the laminar fixed throttles 21; 22; 23; 24 and 25, respectively; 26; 27; 28 a constant pressure drop, with that in the respective table guide-related carrier bags 4; 5 or 6; 7 existing print as a product with the supporting surface of the respective table guide, for machine table 2 or rotary table 3 keeps the balance of an external load. The one under these specific equilibrium conditions in the carrier bags 4; 5 or 6; 7 of the respective table guide conveyed pressure flow forms a bearing gap of a certain size. That in the bearing gap of a table guide, In the exemplary embodiment, the lower table guide was chosen for this, prevailing Pressure is measured at several points, each with a p-u converter 32:33 and converted into an analog electrical quantity. These electrical quantities are in the Summing element 34 is added and in the downstream setpoint generator module 35, an averaging and an adjustment, according to the pressure gradient across the fixed throttles 22; 23, and this adjusted mean value as the pressure setpoint issued. For the few table guides, their pressure in the bearing gap no measurement is subjected in the exemplary embodiment that is the upper table guide, takes place Obtaining the pressure setpoint in the way that the output of the summing element 34 parallel to the setpoint generator module assigned to this table guide 36 is placed, in which the adapted to the load of this table guide Average value formed and output as a pressure setpoint for the upper table guide will. The multiple setpoint generator assembly 31 thus allows electronic means a powerless measurement and for setting up the table guides with several combinations Throttle point - carrying bag and common pressure control circuit an averaging from several bag presses and thus a representative target value generation.

The summing members 37; o8 attached Sign-weighted setpoint pressure values are converted from the p-u converters 41; 42 The signed-weighted actual pressure values obtained are summed up. In addition, a viscosity-dependent controlled variable taken into account from the outputs of the multiple temperature evaluation module 44 is made available and also signed with the table guide-related Summers 37; 38 is applied, the measured at the pressure medium temperature measuring point 43 For this purpose, the temperature is converted by the T-u converter 45 into an analog electrical variable and converted into a control variable in the correction value generator 46, the from one nonlinear network existing correction element 47 the temperature-dependent viscosity curve replicates. The adaptation members 49; SO allow this controlled variable to be adjusted on the table guide-related pressure medium temperature in the bearing gap.

This also takes account of designs in which the pressure medium temperature measuring point 43 not directly on or in the bearing gap, but for example in the storage container 10 or at another easily accessible point at which a temperature difference to the temperature in the bearing gap. The from the control amplifiers 51; 52 taking place Provision of the controlled variables is based on optimal adaptation, through static and dynamically optimal controller structure by means of the PID members 53; 54 and that made it possible Circular reinforcement, to the Jevreilige table guide to achieve a load-independent Bearing gap constancy. Except for a very small remaining system deviation from Controlled variables of the control amplifier that go to zero 51; 52 regulate the Actuators 57; 58 to a bypass pressure medium flow via the bypass lines 59; 60, which shows the pressure ratio of the pressures upstream and downstream of the leminary fixed throttles 21; 22; 23; 24 and 25, respectively; 26; 27; 28 holds constant. Are the laminar fixed throttles 21; 22; 23; 24 and 25, respectively; 26; 27; 28 table guide-related with a certain bearing gap size optimized to the effect that their throttle resistance is equal to the taiderstand of the bearing gap is, then there is a certain constant pressure ratio of the pressures before and behind the laminar fixed throttles 21; 22; 23; 24 and 25, respectively; 26; 27; 28. These two Conditions, the resistances and the pressures ensure that when there are changes the workpiece load F a pressure medium flow is provided, which despite the changed Load of the table guides the bearing gap size is kept constant.

Setting or changing the size of the bearing gap is easy and controllable way by setting a corresponding pressure setpoint at the corresponding setpoint generator module 35 or 36. This advantage works especially in applications that take dynamic load changes into account off, whereby the same laminar fixed throttles are related to the carrier bag and each have their own Control loop are assigned. The same advantages in terms of setpoint adjustment result for use on a table guide whose individual table guide tracks, For example, due to asymmetrical workpieces, are unevenly loaded. For this is a device shown in the drawing of the embodiment Kind of suitable, with the required pressure setpoint for the individual table guideways to the setpoint generator module 35; 36 is individually adjustable.

List of the reference symbols used 1 - table guide track 2 - machine table 3 - rotary table 4 "carrying bag 6- -" 7 8 - pressure generator 9 ~.

10 - Reservoir 11 - Main pressure line 12-13 - Pressure line 14 -15 -16 -17 -18 -19 -20 -21 - laminar fixed throttle 22 -23 - "" 24 - tu 25 - "" 26 "27 ~, 28 - tu tu 29 - secondary line 30 - tu 31 - multiple setpoint generator assembly 32 - p-u-converter 33 -34 - summing element 35 - setpoint generator S'lock 36 - 37 - table guide related Sulmmier member 38 - * tu 39 - secondary line 40 - "41 - p-u converter 42 -43 - Pressure medium temperature measuring point 44 - Multiple temperature evaluation module 45 - T-u converter 46 - Correction value generator 47 - Correction element (non-linear network) 48 - operational amplifier 49 - adapter 50 tu 51 - control amplifier 52 - tu 53 - PID element 54 - tu 55 - operation amplifier 56 - "57 - actuator 58 - tu 59 - bypass line 60 - tu F - workpiece load

Claims (12)

Hydrostatically load-compensated storage, preferably several on top of each other arranged table guides Patent claims 1 Hydrostatically load-compensated bearing, preferably several table guides arranged one above the other. being the bearing gap the table guide via carrier bags from a pressure generator via throttling points a pressure current is supplied and depending on the load on the table guide an assigned regulator regulates the pressure in the inlet to the prosel positions, as well as further control engineering means for eliminating the effects of changes in viscosity of the pressure medium are provided on the bearing gap size, characterized by ~, that of at least two between the throttle points and these associated carrier bags (4; 5) running pressure lines (14; 16) of a table guide secondary lines (29; 30) deducted and on the input side to an electronic single or multiple setpoint generator module (31) are connected, the output side to an input of a table guide-related Summing element (37; 38) is connected, at the other input of which the output of a p-u converter (41; 42) is applied, the input-side secondary line (39; 40) of a table guide-related pressure line (14; 17), in the direction of flow of the pressure medium before the assigned throttle point, branched off is at least a pressure medium temperature measuring point (43) an electronic single or multiple temperature evaluation module (44) and on the output side to another input of the table guide-related Summing element (37; 38) is connected, the output of which is connected to a control amplifier (51; 52) and this with its output on an actuator (57; 58) in a Bypass line (59; 60) of the table guidance-related main pressure line (ii; 12) switched is, 2, hydrostatic load-compensated mounting according to claim 1, characterized. that the electronic single setpoint generator module on the input side each secondary line (29; 30) assigned p-u converter (32; 33), whose Outputs are connected to a summing element (34) and this with its output to a setpoint generator module (35), the output of which is that of this module is. 3. Hydrostatically load-compensated storage according to claim 1, characterized marked. that the electronic multiple setpoint generator assembly (31) on the input side of each secondary line (29; 30) one of several table guides arranged one above the other or p-u transducers assigned to a table guide by a table guide track (1) (32; 33), the outputs of which are connected to a Summlor member (34) and this with its output parallel to each of the table guides arranged one above the other or the setpoint generator modules belonging to the individual table guideways (1) of a table guide (35; 36) is performed, the outputs of which are those of this assembly. 4. Hydrostatically load-compensated storage according to claim 1, characterized marked. that the electronic single temperature evaluation module on the input side a temperature sensor with T-u converter (45), which with its output switched to a correction value generator (46) and this to an adapter (49) is applied, the output of which is that of this temperature evaluation module. 5. Hydrostatically load-compensated storage according to claim 1 and 4, characterized. that the electronic multiple temperature evaluation assembly (44) consists of a single temperature evaluation assembly, the output of the Correction value generator (46) in parallel with reference to a table guide or related to a table guide path for a table guide and each on an adapter (49; 50) whose outputs are those of the multiple temperature evaluation module (44) are 6. Hydrostatic load-compensated storage according to claim 1, 4 and 5, characterized characterized1 that the correction value generator (46) consists of a correction element (47) feedback operational amplifier (48) consists. 7. Hydrostatically load-compensated storage according to claim 1 and 4 to 6, characterized in that the correction element (47) consists of a non-linear network consists. 8. Hydrostatically load-compensated storage according to claim 1. characterized in that the control amplifier (51; 52) by a is implemented via a PID element fed back operational amplifier (55; 56). 9. Hydrostatically load-compensated storage according to claim 1, characterized characterized in that a motor-adjustable throttle is used as the actuator (57; 58) is. 10. Hydrostatically load-compensated storage according to claim 1, characterized characterized in that a proportional valve is used as the actuator (57; 58). 11. Hydrostatic load-compensated storage taking into account dynamic load changes according to claim 1; 2; 4th and 6 to 10., characterized in that each carrying case (4; 5) of the table guide has a control circuit assigned to the electronic single setpoint generator module related to the carrying case is. 12. Hydrostatic load-compensated storage according to claim 1 characterized characterized in that as throttle points 21; 22; 23; 24 and 25, respectively; 26; 27; 28 table guide-related Optimized laminar fixed throttles of the same size are provided.