DE102009024291A1 - Pivot bearing i.e. antifriction bearing, for use in crankshaft grinder, has actuators acting in radial direction of bearing ring, where bearing ring and actuators are formed such that bearing ring is deformable by actuators - Google Patents

Abstract

The bearing has a bearing ring (18) formed at a frame side and possessing a bearing ring centroid (S14). Three actuators (22.a-22.c) act in a radial direction of the bearing ring, where the bearing ring and the actuators are formed such that the bearing ring is deformable by the actuators. The actuators are designed as piezo actuators, and a sensor is provided for detecting a measured variable, where shifting of the bearing ring centroid and/or a change of a bearing clearance are adjustable by actuation of the actuators. Independent claims are also included for the following: (1) a positioning machine i.e. robot, comprising a frame and a tool receptacle (2) a method for fine machining of a workpiece.

Description

The The invention relates to a rotary bearing with a shaft-side bearing ring, which has a geometric bearing ring center of gravity, a frame-side bearing ring and at least one actuator, at least in the radial direction acts on at least one of the bearing rings. According to a second aspect relates to Invention a fine machining process for fine machining a Workpiece.

such Rotary bearings, for example in the form of rolling bearings, for example Used in grinding machines for grinding crankshafts be used. The manufacture of crankshafts involves forging a blank an unbalance analysis. Based on the Imbalance analysis centering holes are introduced into the blank and the blank subsequently cured. After hardening The blank is clamped and ground in the centering holes. After grinding, an iterative process follows from unbalance analysis and balancing by suitable material removal on the crank webs, until the unbalance of the crankshaft is below a specified critical Imbalance lies. Due to the high speed of the crankshaft in use Only small imbalances are tolerated. It is therefore necessary that the center holes only a few microns from their respective Ideal location may lie.

adversely In the state of the art, the high cost is due to the iterative Determine the imbalance and regrinding.

Of the Invention is based on the object disadvantages of the prior art to overcome.

The Invention solves the problem of a generic pivot bearing, in which at least one of the bearing rings and the at least one actuator so formed are that an actuation the actuator leads to a targeted deformation of the bearing ring. In other Words are the bearing ring and the at least one actuator designed so that the bearing ring is selectively deformable by means of the actuator.

According to one second aspect triggers the invention the problem by a finishing method for fine machining a workpiece, with the steps (i) determining an imbalance of the workpiece, (ii) Controlling at least one actuator, at least one pivot bearing according to the invention, so that the imbalance is reduced, and (iii) finishing the Workpiece.

Advantageous on the invention is that a bearing with the pivot bearing workpiece, for example a Crankshaft, so finely positioned during a grinding process can be that the imbalance is reduced. Because of that Bearing ring is selectively deformed by means of the actuator can, via a deformation the bearing ring of the geometric bearing ring center of gravity and / or a Bearing stiffness or bearing damping changed become. That makes it possible to determine an unbalance of the crankshaft in one clamping and then the at least one actuator to control so that the bearing ring deformed in a way that causes the crankshaft to turn around rotates a rotation axis, so chosen is that after sanding a significantly smaller or no Imbalance is more present.

By deforming the bearing ring by means of the actuator, it is possible to Shift bearing center of gravity in the micrometer range targeted. This in turn allows an extreme fine positioning at the same time greater Stiffness of the pivot bearing, so that, for example, a crankshaft can be finished in one clamping. That saves the usual so far Iteration steps and shortens the Process chain.

Advantageous on the invention is also that the deformation of the bearing ring can be done very quickly. The invention therefore makes it possible to use the geometric Changing the bearing ring center of gravity quickly. That in turn leads to that an in-process control possible is, which is a desired position of the tensioned by the pivot bearing object aligns with an actual position and by controlling the actuator to readjust the situation.

in the The scope of the present description will be below the shaft side Bearing ring that bearing ring understood that the rotating, too facing bearing components. Usually it will be to act around the inner bearing ring.

Under the frame-side bearing ring is that bearing ring understood which rests, which is usually the outer bearing ring is.

Under the at least one actuator is understood in particular to mean every device by means of a targeted force can be applied to the bearing ring, so that it deforms. It is possible that the actuator is force-controlled and / or works remotely. It is also possible that the actor at the same time acts as a sensor. Here are the bearing ring and the at least an actuator designed so that the deformation of the bearing ring causal is for a shift of the geometric bearing ring center of gravity. It can this is a time-varying or over time act constant relocation.

According to a preferred embodiment, the at least one bearing ring and the at least an actuator is designed so that by moving the actuator, a displacement of the bearing ring center of gravity and / or a change ei Nes bearing clearance of the pivot bearing is adjustable. This is understood to mean a reproducible shift or change. Preferably, the rotary bearing is a roller bearing comprising a plurality of rolling elements. If the bearing ring is deliberately deformed by means of the actuator, this results in a change in a circulation curve of the rolling rings. This in turn alters on the one hand a position of the bearing ring center of gravity, on the other hand, a local stiffness of the pivot bearing. The change in local rigidity also indirectly leads to a change in the bearing ring center of gravity. If a radial force is applied to the rotary bearing, for example because a grinding wheel presses on a crankshaft supported by the rotary bearing, an increase in the stiffness of the rotary bearing causes the crankshaft to displace less under the force of the grinding wheel. It is therefore possible to change the rigidity of the rotary bearing locally or as a whole by deliberately deforming the outer bearing ring and thus to change the bearing ring center of gravity.

According to one preferred embodiment at least the frame-side bearing ring at least one desired deformation point which is arranged so that an actuation of the actuator to a deformation the frame-side bearing ring such that the bearing clearance and / or the bearing ring balance changed. The at least one desired deformation point may be, for example around a solid-state joint act. Solid joints are areas of the bearing ring that have a lower strength, so that a deformation of the bearing ring in an environment of Intended deformation point concentrated.

Especially Preferably, the frame-side bearing ring has three or more desired deformation points, those in equidistants Angular steps are arranged. In this way, the deformation can the bearing ring are set particularly defined.

Preferably is the bearing ring in the circumferential direction at least two parts. To this This way, an easy-to-manufacture bearing is obtained, which is also light deformable by applying a force through the actuator is.

Prefers the at least one actuator acts in the radial direction on the frame side Bearing ring. That way to achieve a particularly effective deformation of the bearing ring.

Prefers the at least one actuator comprises a piezoactuator. In particular the actuator is formed by a piezoelectric actuator, alternatively, the piezoelectric actuator also be used to a pneumatic or hydraulic valve to press, wherein the force on the bearing ring then pneumatically or hydraulically via a corresponding piston drive is applied. Especially preferred The pivot bearing comprises at least three actuators, which are in equidistant Angular steps are arranged around the frame-side bearing ring.

According to one preferred embodiment the pivot bearing at least one sensor for detecting at least one Measured variable, off which also closed the position of the geometric bearing ring center of gravity can be. It may be, for example, a position sensor, a speed sensor, an acceleration sensor or a Force sensor act. It is also possible that the sensor is formed is to capture two or more of the sizes mentioned. It is too possible, that the actuator acts as a sensor at the same time. That's for example given when a piezoelectric actuator is used.

Preferably The pivot bearing includes an electrical control unit that is set up is to perform a method comprising the steps of (i) detecting an actual position of a first bearing ring, in particular of the shaft-side bearing ring, relative to a frame of a machine in which the pivot bearing is installed, and (ii) driving the at least one actuator so that the second bearing ring, in particular the frame-side bearing ring, so deforms, that the first bearing ring approaches a desired position. The can be done, for example, that the electrical control unit is set up to drive the at least one actuator so that the spring stiffness of the pivot bearing changes accordingly. at the actual position is, for example, the position of the geometric center of gravity or the center of mass of the pivot bearing or one by means of the Turning bearings stored workpiece.

Under the feature that the electrical control unit is set up to perform the specified steps, is understood in particular that the Control unit has a digital memory, in the program code is stored. The program code executes to that the control unit automatically processes the delivered steps performs.

According to a preferred embodiment, the bearing ring center of gravity of the shaft-side bearing ring is rotatable relative to the frame-side bearing ring with an actuator unactuated actuator, wherein the electrical control unit is configured to drive the at least one actuator so that a spring stiffness of the pivot bearing changes so that the bearing ring center of gravity rotates about a compensation axis of rotation displaced parallel to the actual axis of rotation. For this purpose, the electrical control unit in particular specially adapted for detecting a rotational position of the shaft-side bearing ring and for determining a force acting on the rotary bearing force.

Prefers the control unit is set up to perform a procedure with the Steps (i) detecting the at least one measured variable, determining a manipulated variable, in particular an electrical voltage based on at least one measurand and (ii) Actuation of the at least one actuator with the manipulated variable, so that the bearing ring center of gravity occupies a predetermined position. Prefers However, it is provided that the actuator in its damping constant adjustable is trained.

in the Below, the invention will be described with reference to an exemplary embodiment explained in more detail. there shows

1 a perspective view of two pivot bearings according to the invention, by means of which a shaft is mounted,

2a a frame-side bearing ring of a rotary bearing according to the invention and three actuators in the inactive state,

2 B according to the bearing ring 2a in the state in which the actuators are active,

3 a schematic view of a pivot bearing according to the invention,

4 a second schematic view of a second embodiment of a pivot bearing according to the invention and

5 with the subfigures 5a and 5b schematically shows a grinding machine according to the invention.

1 shows a first inventive pivot bearing 10.1 in the form of a movable bearing and a second inventive pivot bearing 10.2 in the form of a permanent camp. By means of the two pivot bearings 10.1 . 10.2 becomes a wave 12 rotatably mounted. The two pivot bearings 10.1 . 10.2 are structurally the same, with the respective elements for the pivot bearing 10.2 carry the counting suffix ".2", that for the pivot bearing 10.1 the counting suffix ".1". Reference numerals without counting suffix designate the object as such.

The pivot bearing 10.2 has a shaft-side bearing ring 14.2 , which has a geometric bearing ring center of gravity S ₁₄ in the unstressed state on a longitudinal axis L of the pivot bearing 10.2 lies. In the unstressed state, the longitudinal axis L is also the longitudinal axis of the pivot bearing 10.1 and the wave 12 ,

The pivot bearing 10.2 also includes a variety of rolling elements 16.a , 16.b . 16.c , ..., around the shaft bearing ring 14.2 circulate. The rolling elements 16 be from a frame-side bearing ring 18.2 captured.

2a shows the frame-side bearing ring 18 , which is made of metal, for example steel. The frame-side bearing ring 18 has three nominal deformation points 20.a . 20.b . 20.c on. The desired deformation points 20 are formed by material weakenings in the otherwise circumferentially homogeneous stiffness having rack side bearing ring 18 ,

Between every two deformation points 20 is a respective actor 22.a . 22.b respectively. 22.c arranged. The actors 22 are piezo actuators, which are connected via not shown electrical lines with an also not shown electrical control unit. The bearing ring center of gravity S ₁₄ is located in the geometric center of gravity of a geometric inner circle of the frame-side bearing ring 18 ,

2 B shows the case that the actuator 22.a is subjected to an electrical voltage so that it elongates and at its base 24.a on the frame-side bearing ring 18 suppressed. As a result, the frame-side bearing ring deforms 18 , this deformation being in 2 B is shown greatly inflated.

Due to the two target deformation points 20.a and 20.b , on both sides of the actor 22.a are arranged decreases in an environment of the foot 24.a a curvature K _{1 of} the frame-side bearing ring 18 , The curvature K ₁ is smaller than a curvature K _{0 of} the unstressed frame-side bearing ring 18 , Also in the area of the foot points 24.b of the sensor 22.b and 24.c of the sensor 22.c the respective curvatures K ₂ and K _{3 are} smaller than the curvature K ₀ . The frame-side bearing ring 18 is less curved at these points. In contrast, the bearing ring 18 adjacent to the desired deformation points an increased curvature, it is K ₄ , K ₅ , K ₆ > K ₀ .

By the pressure of the actuator 22.a on the frame-side bearing ring 18 and the resulting deformation shifts the geometric bearing ring focus 814 from its original position to a resulting position, designated as S _'14 . It shifts therefore also in 1 shown wave 12 so that by means of the actor 22.a the location of the shaft 12 can be influenced. By actuating another actuator or two or three actuators can be another position of the shaft 12 set in a predetermined range of possible positions.

3 shows a schematic view of the pivot bearing 10 with four actuators 22.a . 22.b . 22.c . 22.d , in each foot on the frame side bearing ring 18 attack. The respective foot point 24 turned away, the actuators are based on a schematically drawn frame 26 from.

In the enlarged oval limited section is the actuator 22.a indicated schematically in its effects. So can the actor 22.a be caused by applying an electrical voltage to cause the foot point 24.a relative to the frame 26 shifts. That's through the two positions 26 and 26 ' characterized.

The sensor 22.a also has the effect of an adjustable suspension with a spring constant κ. The actor 22.a also has a damping effect with a damping constant d. The spring constant κ and the damping constant d describe properties of the actuator 22.a together with an indicated, assigned control unit.

The spring constant κ means that the application of an external force F to the actuator 22.a in the floor 24.a leads to a displacement radially outward by a distance .DELTA.x, resulting in the spring constant κ = F / Δx results. Will the actor 22.a in the floor 24.a stimulated pulse-like, so the resulting vibration sounds with the timer e ^{-d * t} . The actor 22.a can also be used as a measuring system to measure the position of the foot point 24.a be educated. This is through the M and the snake-shaped arrows at the actuator 22.b indicated. Alternatively, at least one separate sensor is provided, by means of which by the control unit, the position of the shaft 12 is determined.

4 shows the pivot bearing according to 3 in a schematic view, wherein an electrical control unit 28 is located, which are connected via electrical connections to the respective actuators, which also act as sensors. This is how the control unit stands 28 via an electrical line 30.c in connection with the actuator 22.c and over a line 30.a with the sensor 22.a ,

The control unit 28 continuously records the actual position of the shaft-side bearing ring 14 relative to the frame 26 the machine in which the pivot bearing is installed. By applying the actuators of the frame side bearing ring 18 then deformed so that the bearing ring focus S ₁₄ shifts as desired and the shaft 12 assumes the desired position.

5 shows schematically how a finishing process in the form of a crankshaft pendulum lift grinding is performed. In 5a is a crankshaft 32 between workpiece holders in the form of tips 33.a . 33.b curious; excited. The tips are from pivot bearings 10.3 and 10.4 held, which are constructed as described above. By means of a grinding wheel 34 can the bearing seats of the crankshaft 32 be sanded. The pivot bearing 10.4 is on a tailstock 36 the corresponding grinding machine 38 attached, the pivot bearing 10.3 is either on a second tailstock or on a frame of the grinder 38 assembled.

To carry out the finishing process, in the present case of the grinding process, first an imbalance of the workpiece in the form of the crankshaft 32 certainly. This can for example be done by the crankshaft 32 is rotated, wherein the forces occurring during rotation are detected by the actuators of the pivot bearing, which act as sensors in this case. If it turns out that a nominal axis of rotation A _SOLL deviates from an actual axis of rotation A _IST , then the pivot bearings 10.3 , 10.4 from the in 5 not shown control unit 28 (see. 4 ) so controlled that the actual axis of rotation A _actual coincides with the desired axis of rotation A _target or whose distance is below a present limit value. After that, the crankshaft 32 by means of the grinding wheel 34 finished, so that any iteration steps consisting of balancing and reworking can be performed in one setting.

Advantageous at the pivot bearing according to the invention is that process relocated the focus in the field of less than three microns can be achieved.

2 B also shows that by the action of the actor 22.a a deformation of the frame-side bearing ring 18 entry. This causes that in the environment of the foot point 24.a a higher pressure acts on the rolling elements, in this way increases the bias of the pivot bearing and thus the rigidity. In other words, a higher force must be applied to the shaft side bearing ring on the actuator 22.a to move as if the actor 22.a would be inactive.

If now in 5 the actor 22.a arranged down, so leads from the grinding wheel 34 also downwardly acting passive force F _p to the crankshaft 34 in the pivot bearings 10.3 and 10.4 is pressed down. Will now the actor 22.a operated, the rigidity of the bearing and the crankshaft increases 32 moves against the passive force F _p upwards. This results in the described displacement of the rotation axis A.

The actors 22 can have a multiple function. The first function is to set a center position of the bearing so that an average force acts on the shaft. The second function is It uses sensors (sensor and transformer) to adjust the position, speed and acceleration as well as the force and the characteristic diagram of the actuator, the exact position and force of the actuator. In this case, the transfer function of the actuator can be used and processed as a map or system of equations in the superimposed control in the computer system (evaluation unit computer system and algorithm for control).

The third function is to brace the bearing so that the supply of the warehouse over the adjustment mechanism of the outer fixed point can be adjusted. The actuator is usually a linear actuator and so executed, that it has an adjustable stiffness and an adjustable damping and his length changes depending on the state of control. As an alternative to the piezoelectric actuator electromagnets can be used be, with the actuators be pneumatically or hydraulically supported can.

Also the combination of a linear actuator with a rotary actuator for angular error is possible. Further can the damping be continuously adjusted by an actuator. This is the control unit used so that a detected force acting on the actuator to a loading of the actuator with a voltage leads the a certain, the force counteracting force generated.

extended has the unit over an elastic adjustment mechanism, which is designed so that the outer bearing ring divided and / or by elastic solid joints (articulated bearings) accomplished is. The roller conveyor of the rolling bodies can also be affected be. These Duly is the process by which the actuator is regulated by feedback control which is implemented on a computer unit (evaluation unit) is and stops the process during operation. That's it System over a connection (mechanical / electrical) with the control unit in contact. Fine positioning applications are just like applications conceivable in the field of unbalance compensation.

10

pivot bearing

12

wave

14

shaft-side bearing ring

16

rolling elements

18

frame side bearing ring

20

Target deformation zone

22

actuator

24

nadir

26

frame

28

control unit

30

management

32

crankshaft

33

Workpiece holder

34

grinding wheel

36

tailstock

38

grinding machine

A _REQUEST

Desired axis of rotation

A _IS

Actual rotational axis

F _p

piezo actuator

K

curvature

κ

spring constant

d

damping constant

L

longitudinal axis

S ₁₄

Race-focus

Claims (19)

Pivot bearing ( 10 ) with (a) a shaft-side bearing ring ( 14 ), which has a geometric bearing ring center of gravity (S ₁₄ ), (b) a bearing-side bearing ring ( 18 ) and (c) at least one actuator ( 22 ), at least in the radial direction on at least one of the bearing rings ( 14 . 18 ), characterized in that (d) at least one of the bearing rings ( 18 ) and the at least one actuator ( 22 ) are formed so that the bearing ring ( 18 ) by means of the actuator ( 22 ) is selectively deformable. Pivot bearing ( 10 ) according to claim 1, characterized in that the at least one of the bearing rings ( 18 ) and the at least one actuator ( 22 ) are formed so that by actuating the actuator ( 10 ) a displacement of the bearing ring center of gravity (S ₁₄ ) and / or a change of a bearing clearance of the pivot bearing ( 10 ) is adjustable. Pivot bearing ( 10 ) according to one of the preceding claims, characterized in that at least the frame-side bearing ring ( 18 ) at least one desired deformation point ( 20 ), which is arranged so that an actuation of the actuator ( 22 ) to a deformation of the frame-side bearing ring ( 18 ) in such a way that the bearing clearance changes. Pivot bearing ( 10 ) according to one of the preceding claims, characterized in that at least the frame-side bearing ring ( 18 ) three or more desired deformation points ( 20.a . 20.b . 20.c ), which are arranged in equidistant angular steps. Pivot bearing ( 10 ) according to one of the preceding claims, characterized in that the at least one actuator ( 22 ) in the radial direction on the frame-side bearing ring ( 18 ) acts. Pivot bearing ( 10 ) according to one of the preceding claims, characterized in that the at least one actuator ( 22 ) comprises a piezoelectric actuator. Pivot bearing ( 10 ) according to one of the preceding claims, characterized by at least one sensor ( 22 ) for detecting at least one measured variable, by means of which the position of the bearing ring center of gravity (S ₁₄ ) can be concluded. Pivot bearing ( 10 ) according to one of the preceding claims, characterized by an electrical control unit ( 28 ), which is set up for carrying out a method with the steps: (i) detecting an actual position of a first bearing ring, in particular of the shaft-side bearing ring ( 14 ), relative to a frame ( 26 ) of a machine, (ii) driving the at least one actuator ( 22 ), so that the second bearing ring, in particular the frame-side bearing ring ( 18 ), deformed so that the first bearing ring approaches a desired position. Pivot bearing ( 10 ) according to one of the preceding claims, characterized in that - the bearing ring center of gravity (S ₁₄ ) of the shaft-side bearing ring (S ₁₄ ) 14 ) with unactuated actuator ( 22 ) about an actual axis of rotation (A _IST ) relative to the frame-side bearing ring ( 18 ) is rotatable, - wherein the electrical control unit is configured to drive the at least one actuator ( 22 ) so that a spring stiffness of the pivot bearing ( 10 ) so that the bearing ring center of gravity (S ₁₄ ) rotates about a desired axis of rotation parallel to the actual axis of rotation offset by an offset (A _SOLL ). Pivot bearing ( 10 ) according to claim 8 or 9, characterized in that the control unit is adapted to perform a method comprising the steps of: - detecting the at least one measured variable, - determining a manipulated variable, in particular an electrical voltage, based on the at least one measured variable and - applying at least an actor ( 22 ) With the manipulated variable, so that the bearing ring center of gravity (S ₁₄ ) occupies a predetermined position. Pivot bearing ( 10 ) according to one of the preceding claims, characterized by a damper adjustable in its damping constant (d). Positioning machine, in particular machine tool or robot, with - a frame ( 26 ) and - at least one pivot bearing ( 10 ) according to any one of the preceding claims attached to the frame ( 26 ) is attached. Positioning machine according to claim 12, characterized by - a first workpiece holder ( 33.a ) for picking up a workpiece ( 32 ) with one of the bearing rings ( 14 ) and - a drive for rotating the workpiece, - wherein the electrical control unit ( 28 ) is arranged to carry out a method with the steps: continuous detection of an actual axis of rotation (A _actual ) of the workpiece, continuous activation of the at least one actuator ( 22 ), So that the actual rotational axis (A _IS) of a desired axis of rotation (A _SOLL) approaches. Positioning machine according to claim 12 or 13, characterized by - a second pivot bearing ( 10 ) according to one of claims 1 to 9, - wherein the electrical control unit ( 28 ) is arranged to perform a method comprising the steps of: detecting a wobble error of the workpiece ( 32 ), continuous activation of the at least one actuator ( 22 ) of the first pivot bearing ( 10 ) and / or the at least one actuator ( 22 ) of the second pivot bearing ( 10 ), So that the actual rotational axis (A _IS) of a desired axis of rotation (A _SOLL) approaches. Positioning machine according to claim 14, characterized characterized in that it is a crankshaft grinding machine. Finishing method for fine machining a workpiece, comprising the steps of: (i) determining an imbalance of the workpiece ( 32 ), (ii) driving at least one actuator ( 22 ) at least one pivot bearing ( 10 ) according to one of claims 1 to 9, so that the imbalance is reduced, (iii) finishing the workpiece ( 32 ). A method according to claim 16, characterized in that the driving of the at least one actuator ( 22 ) of the at least one pivot bearing ( 10 ) driving at least a first actuator ( 22 ) of the first pivot bearing ( 10 ) and / or driving at least one second actuator ( 22 ) of a second pivot bearing ( 10 ) according to any one of claims 1 to 9. Method for grinding a crankshaft ( 32 ), comprising the steps of: determining a desired position of a hardened crankshaft blank, driving the at least one first actuator 22 ) of the first pivot bearing ( 10 ) and / or driving the at least one second actuator ( 22 ) of the second pivot bearing ( 10 ) so that the crankshaft blank extends along a desired axis of rotation (A _SOLL ) and - grinding the crankshaft blank. A method according to claim 18, characterized in that the finishing is a loop fen, in particular a pendulum, is.