DE102008001861A1 - Method for centric aligning of element relative to another element, involves adjusting element relative to another element in two directions, particularly in two linear independent directions - Google Patents

Abstract

The method involves adjusting an element (1) relative to another element (9) in two directions, particularly in two linear independent directions. The electrical capacity of an electrical condenser or a measured variable dependent on this capacity is measured during the relative adjustment of the elements. An independent claim is included for a device, particularly machine tool, for centric aligning an element relative to another element.

Description

State of the art

The The invention relates to a method for, in particular centric, Aligning a first element relative to a second element according to the preamble of claim 1 and a Device, in particular a machine tool, according to the The preamble of claim 10.

From the EP 1 541 282 B1 a method for aligning a tool relative to a workpiece on a machine tool is known in which a desired position (alignment position) of the elements to each other is calculated on the basis of four actual positions of the workpiece relative to the tool, wherein the actual positions Detection of a contact (short circuit) of the two elements are determined. The known method has proven itself. The disadvantage, however, is that the method is sensitive to dirt, since located between the workpiece and the tool dirt particles can prevent a short circuit. The same applies with regard to a possible formation of a short-circuit preventing oxide layers. In addition, the use of the method is then problematic in terms of achievable accuracy when the diameter ratio of the tool and a cylinder bore of the workpiece, relative to which the tool is to be aligned, is in the vicinity of 1. In this case, actual positions can not be determined exactly.

Disclosure of the invention

Technical task

Of the Invention is therefore the object of an opposite Dirt-resistant alignment method for alignment to propose two, in particular electrically conductive, elements. Furthermore, the object is to provide a correspondingly optimized device, In particular, a machine tool to propose, with or on the two elements, in particular a workpiece to a Tool relative to each other, preferably centric, exactly aligned can be.

Technical solution

These Task is in terms of the method with the features of the claim 1 and with regard to the device with the features of the claim 10 solved. Advantageous developments of the invention are specified in the dependent claims. Within the scope of the invention all combinations of at least two of in the description, the claims and / or the figures revealed Features. To avoid repetition should be disclosed according to the method Features also disclosed as a device apply and be claimable. Likewise, according to the device disclosed Features as disclosed according to the method apply and claimable.

Of the Invention is based on the idea, the arrangement of the first and the second element as a capacitor to nut nut and, in particular during the relative displacement of the elements to each other, the electrical Capacity of this, in particular as a cylindrical capacitor trained, capacitor and / or a capacity-dependent Measure to measure. This can be the capacity or the measured variable, as explained later will be used to determine actual positions of the two elements be used relative to each other, then based on the target position (Alignment position) of the elements is calculated to each other. Additionally or alternatively it is, as will be explained later is possible, by a, in particular continuous, Capacity or measurement measurement on one, in particular symmetrical, trajectory of one of the elements Capacity or measured variable course too determine, d. H. at a variety of on this trajectory located actual positions, the capacity or the measured variable to determine and based on this information, the target position (Alignment position) to determine. In any case, independent from the concrete realization of the procedure, the procedure can be carried out without contact - d. H. a mechanical striking of the elements together, as this is necessary in the art, is usually avoided. This is especially true for high precision, especially electric conductive, elements of advantage, since in every mechanical Contact on, at least minimal, chip removed or at least one of the elements is deformed. It is preferable one of the elements around a workpiece to be machined and the other element is a tool for machining the workpiece. As a tool comes in particular the use of an erosion electrode, a milling tool, a drilling tool, a grinding tool or a laser tool into consideration. Particularly preferred the workpiece while a, example, as a stepped bore trained, bore relative to the (in the) the tool, in particular centric, to be aligned, preferably such that the Tool is aligned centrally to the inner circumference of the bore.

When it is said in the description of it that the first element is adjustable relative to the second element, this can be realized such that the second element is fixed and only the first element is actively adjusted. Likewise, the opposite case can be realized that the second element is actively adjusted, while the first element is fixed. It is also an embodiment feasible, in which both elements, one after the other or simultaneously, are actively adjusted. Preferably, at least one of the piezoelectric actuators is used for adjusting at least one of the elements, since precise adjustment paths can be realized with this. However, a trained according to the concept of the invention method is not limited to use in a workpiece / tool combination. The method can be used in all areas with high accuracy requirements for a, in particular concentric, alignment of two, in particular at least partially electrically conductive, elements. The measurement variable that can be measured in addition to or alternatively to the capacitance may be, for example, a resonance frequency of an LC resonant circuit whose capacitor (capacitance) is formed by the elements to be aligned.

Under "during Relativverstellens of the elements "can according to a first alternative understood that the Relativverstellbewegung the Elements at the time of measurement or for the purpose of measurement interrupted is, d. H. the Relativverstellbewegung takes place in steps. Prefers However, this is a second alternative, where the measurement of capacity or the capacity-dependent size during a relative movement of the two elements takes place to each other.

In a development of the invention, it is advantageously provided that the capacitance and / or measured variable measurement is used to determine defined actual positions of the first element relative to the second element. In other words, in such an embodiment of the method, the capacitance or measured variable measurement is used instead of a short circuit monitoring required in the prior art. Preferably, the geometric shape of at least one of the elements, preferably both elements, is known at least in the mutually aligning region. By way of example, the contour of the first element is a circular inner contour of a bore and the contour of the second element is a circular outer contour. In this case, the positions at which the measured capacitance or the capacitance-dependent measured variable reaches a defined value are preferably stored as actual positions. Upon reaching such a defined value, the two elements have a defined distance from each other, so that when several such actual positions are determined from these (with knowledge of the geometry of the elements) the desired position (alignment position) of the elements relative to each other, in particular analogous to EP 1 541 282 B1 , is calculable.

Especially preferred is an embodiment of the invention in which the two elements along a first axis in a first direction be moved relative to each other until the capacity or the Capacity-dependent measured variable reaches a defined value. Upon reaching the defined value the associated relative actual position is saved. Then the direction of relative movement is reversed and a second Actual position is stored at which the defined value, preferably the same defined value as before is reached. Thereupon become the elements preferably moved to the original position, whereupon the procedure described above along a second, in particular to the first axis extending at right angles, axis is repeated. Particularly preferred are the particular crossing Axes about axes of movement of a machine tool on which the process is preferably carried out.

alternative the two elements are relative to each other along a first Axis, preferably in two opposite directions of movement adjusted, whereby an actual position is stored, at which the measured capacity is minimal or that of capacity dependent size (depending on the type of measured variable) is minimal or maximum. After that, the elements become relative to each other along a second, in particular at right angles to the first axis running, axis moved. Based on the two specific actual positions is, in particular knowing the contour of at least one of the elements, the desired position, d. H. the alignment position of the elements relative calculable to each other. The nominal position results directly from the coordinates of the actual positions.

According to one Alternative method variant, the actual positions are not depending on the measured capacities or Measurements determined, but it becomes a Variety of actual positions along a defined relative movement path each of the elements of the associated capacity value or the associated capacitance-dependent measured variable determined, so that a capacity or measured variable course along the, preferably symmetrical, relative movement path of Elements to each other is obtained. Follows the capacity history or the course of the measurement is not expected History, is the capacity size history or the measured variable course in a circular, for example Relative motion path is not constant, the logic unit recognizes that the center of the circular relative motion path is spaced from the desired position. Based on the determined Information can be a logic unit in the sequence the target position calculate at which the capacity or measured variable course the expected capacity or measured variables equivalent.

Particularly preferred is an embodiment of the method with contact protection. Different out Pressing the relative movement between the elements is stopped when a contact between the elements, for example by detecting a current flow, is detected. As a result, malfunctions of a device carrying out the method, in particular of a machine tool, can be prevented.

As previously mentioned, it is particularly preferred if the axes, along which the elements are adjusted relative to each other, are arranged crossing each other. Preferably, the axes are about movement axes of a machine tool.

Especially it is preferred if the first element is a tool, in particular an erosion electrode, and the second element a workpiece, in particular with a, in particular circular, contoured Bore, is. Alternatively, the first element may be a workpiece and the second element is a tool, in particular an erosion electrode, be.

In Development of the invention is provided with advantage that the Procedure is performed on a machine tool.

To the Increasing the measurement sensitivity, it is preferable if in particular radially, between the two elements a dielectric, in particular a liquid is provided.

The Invention also leads to a device, in particular a machine tool, for aligning two elements (preferably Workpiece and tool) relative to each other. The device includes logic means for storing a plurality of actual positions the elements relative to each other, possibly with associated measured values (Capacity values, capacity-dependent Measurements). Signal-conducting with the logic means are means of measuring the electrical capacity or a capacity-dependent measured variable connected to, as explained by the method described above, Determine / store actual positions of the elements relative to each other and / or to a plurality of actual positions the respectively associated Save capacity or measured value to be able to.

A Possibility to measure a capacity-dependent The measure is that of the elements formed, in particular cylindrical, capacitor to integrate into an LC resonant circuit and as a capacitive Measured variable the resonant frequency of the resonant circuit to mes sen, which is dependent on the generator frequency of the resonant circuit.

Especially preferred is an embodiment of the device, in the means for detecting a, in particular electrical and / or mechanical, contact of the elements are provided, wherein the means preferably signal-conducting with a control device or the aforementioned logic means are connected to Detecting a contact (collision) to interrupt the alignment process.

Brief description of the drawings

Further Advantages, features and details of the invention will become apparent the following description of preferred embodiments as well as from the drawings. These show in:

1 FIG. 2: a longitudinal section through a workpiece with a predrilled bore into which an electrode has been inserted, FIG.

2 FIG. 2: a schematic representation of an LC resonant circuit whose capacitor is formed by two elements which are to be aligned relative to one another,

3 : the capacity curve during the relative displacement of two elements to be aligned along an axis,

4 : a schematic representation of an exemplary embodiment of the alignment method, in which the determination of the setpoint position S is carried out by a minimum determination of capacities,

5 : different stages of an alternative embodiment of the method and

6 in a schematic representation of a method step of an alternative embodiment of the method.

embodiments the invention

In The figures are the same elements and elements with the same Function marked with the same reference numerals.

In 1 is a first element 1 (Workpiece) partially cut and shown greatly enlarged. In the first element 1 are before a erosion a blind hole 3 and a stepped bore 5 available. Between the blind hole 3 and the stepped bore 5 There is no connection before the erosion process. The aim of a processing to be carried out following the process to be described is, between the blind hole 3 and the stepped bore 5 a thin hole 7 , in the 1 indicated by a dashed line to work out. This hole 7 For example, it may have the function of a throttle, especially if the first element 1 is a component of a fuel injector.

The stepped bore 5 consists of a first cylindrical section 5a a conical section 5b and a second cylindrical portion 5c , How out 1 can be seen, the transition between the conical section 5b and the second cylindrical portion 5c be rounded.

The hole 7 is using a second element 9 (Electrode) in an electrode guide 11 is stored and guided, produced by spark erosion (not shown). The method of spark erosion per se is known in the art and any person skilled in manufacturing technology, so that is dispensed with further explanations.

The second element 9 that's like the first element 1 is electrically conductive, can in the direction of a Z-axis from the electrode guide 11 be moved out. This movement of the second element 9 in the direction of the Z-axis is referred to below as a feed movement.

The hole 7 is completed when the lower end of the second element 9 the blind hole 3 has reached. Because of the diameter of the hole 7 and also on the hydraulic properties of both the bore 7 as well as the conical stepped bore 5 and the blind hole 3 high demands are made, it is necessary to drill the hole 7 exactly in the middle of the second cylindrical section 5c the stepped bore 5 to place. In addition, the diameter of the hole 7 be made very accurately.

In the in 1 shown position of the second element 9 this is not exactly centered in the second cylindrical section 5c the stepped bore 5 , The second element 9 is rather positioned slightly offset to the left from the middle. This is undesirable and must be corrected before starting the erosion process. This correction or the determination of the desired position of the second cylindrical portion 5c the stepped bore 5 or the first element 1 relative to the second element 9 will be described below with reference to various embodiments.

The core of the process is that during the relative displacement of the two elements 1 . 9 (ie during movement or during breaks in motion) the capacity or a capacity-dependent measure of one of the elements 1 . 9 educated, in 2 schematically shown capacitor 12 is measured. One possibility for this is to design the capacitor, which is designed as a cylindrical capacitor in the embodiment shown 12 into an LC resonant circuit 13 to integrate, in addition to the capacitor 12 an inductance 15 and a frequency generator 17 includes. In the example in 2 shown resonant circuit 13 are means 19 for measuring the capacitance of the capacitor 12 or a capacitance-dependent measured variable, in this case the resonance frequency f of the LC resonant circuit 13 , integrated. The means 19 are signal-conducting with not shown logic means one in 1 only partially indicated device (machine tool) connected, wherein the logic means for determining and storing actual positions are optionally formed with the associated capacity and / or capacity-dependent measures.

In 3 is in a diagram of the capacity curve over relative positions of the first element 1 relative to the second element 9 shown along the X-axis. It can be seen that the capacity in a middle area is minimal and close to the second element 9 is maximum. For determining two actual positions of the first element 1 relative to the second element 9 it is now possible for example, as later with reference to 4 will be explained, with a relative movement of the elements 1 . 9 to determine the minimum capacity along two intersecting axes. In the case of a circularly contoured bore, its center point (nominal position) can then be determined by determining the point of intersection of two straight lines running at right angles to one another, each straight line passing through an associated actual position (minimum capacity position) on the X or Y axis , This procedure is schematic in 4 shown. In 4 is a section along the section line AA according to 1 shown. To recognize further is the of the elements 1 . 9 formed capacitor 12 , Initially, the relative displacement of the elements 1 . 9 along a X-axis, a first actual position [x ₁ , 0] determined by the capacitance of the capacitor 12 is minimal. Then it is returned to the original position and it becomes the elements 1 . 9 Adjusted along a Y-axis extending perpendicular to the X-axis, during which the actual position [0, y ₁ ] is determined during this adjustment. The target position (alignment position) has the coordinates [x ₁ , y ₁ ] in the sequence and lies at the intersection of two intersecting, through the actual position [x ₁ , y ₁ ] extending straight line.

To illustrate another embodiment of an alignment method, FIGS 5 several sections along the section line AA according to 1 at different times T ₀ to T ₆ , wherein the second element 9 occupies different positions. Based on 2 Now is another alternative to the centric alignment of the elements 1 and 9 be described to each other.

In the seven representations of 5 are each the X and the Y axis, analogous to 4 , egg Cartesian coordinate system. The origin of this coordinate system lies in the middle of the second element 9 before starting the measurement of the position of the second cylindrical portion 5c of the first element 1 ,

At time T ₀ is in 2 the position of the second element 9 shown the position of the second element 9 in 1 equivalent. Starting from the position of the second element 9 at time T ₀ become the first element 1 or its second cylindrical section 5c and the first element 1 relative to each other along the X-axis in the drawing plane moves to the left until the measured capacitance reaches a defined value, in particular a maximum value. Upon reaching this defined value, the movement before a mechanical or electrical contact of the elements 1 and 9 completed at time T ₁ . The actual position of the second element 9 at time T ₁ has the coordinates [x ₁ , 0]. However, the defined capacity value to be achieved does not necessarily have to be the maximum achievable capacity value.

In connection with the relative movements of the second element 9 and the first element 1 and the second cylindrical portion 5c the stepped bore 5 It goes without saying that, depending on the design of the machine tool, not shown (EDM) either a machine table on which the first element 1 is spanned, along the X and Y axis can be moved or the electrode guide 11 along the X or Y axis can be moved. For the procedure is irrelevant whether the second element 9 or the first element 1 emotional. There are also combinations of both movements possible.

Starting from the actual position [x ₁ , 0], the second element is in a further method step 9 move to the right along the X axis in the drawing plane.

At time T ₂ , the measured capacitance reaches a defined value which corresponds to a defined distance between the first and the second element 1 . 9 equivalent. Preferably, the capacitance values to be achieved for determining all actual positions are chosen to be the same, so that the distance of the elements 1 . 9 is equal to each other in the determined, stored actual positions to each other. The actual position with the coordinates [x ₂ , 0] is saved.

Subsequently, the second element 9 back to the origin of the coordinate system. This position is reached at time T ₃ . That is, the second element 9 as well as at time T ₀ having coordinates [0, 0].

In a further step, the second element now becomes 9 in the drawing plane move down along the Y-axis until the defined capacity value is reached again, whereupon the third actual position with the coordinates [0, y ₁ ] is stored. In a further step, the second element now becomes 9 in the drawing plane moves up until a capacity value is reached again. The associated actual position with the coordinates [0, y ₂ ] is stored.

From the coordinates [x ₁ , x ₂ , y ₁ , y ₂ ], the center point (set position S) of the second cylindrical portion 5c the stepped bore 5 be calculated. The coordinates of the target position S (set point in the XY plane) are in 2 denoted by x ₃ and y ₃ . Subsequently, the second element 9 move to this target point and then the coordinate system in the desired position S, ie the center of the second cylindrical section 5c , transformed. This transformed coordinate system is at time T ₆ in _FIG 2 marked with the axes X 'and Y'.

When this transformation of the coordinate system in the center (target position S) of the second cylindrical section 5c may have occurred a processing of the first element 1 with the help of the second element 9 , here by eroding, connect. All feed paths can be realized in all three spatial directions.

In 5 is another embodiment of an alignment shown schematically. This is the second element 9 relative to the first element 1 along a circular relative motion path 21 emotional. The non-drawn center of the circular relative movement path 21 deviates from the desired position S (center) of the lower second cylindrical portion 5c the stepped bore 5 from. During the relative displacement between the elements 1 . 9 The capacity or a capacity-dependent variable is continuously measured and stored with the associated actual positions. This results in a sinusoidal capacitance curve. Based on the stored information, the direction and distance can be calculated to be the center of the relative trajectory 21 must be moved so that this center coincides with the target position S (alignment position).

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1541282 B1 [0002, 0008]

Claims (12)

Method for, in particular centric, alignment of a first element ( 1 ) relative to a second element ( 9 ), the first element ( 1 ) relative to the second element ( 9 ) in at least two directions, in particular in two linearly independent directions (X-axis, Y-axis), is adjustable, wherein a desired position (S) (alignment position) of the first element ( 1 ) relative to the second element ( 9 ) on the basis of several by relative displacement of the elements ( 1 . 9 ) achievable actual positions of the first element ( 1 ) relative to the second element ( 9 ) and then the first element ( 1 ) relative to the second element ( 9 ) is adjusted to the desired position (S), characterized in that, in particular during the relative displacement of the elements ( 1 . 9 ), an electrical capacitance of the first and second elements ( 1 . 9 ) formed electrical capacitor ( 12 ) or a measured variable dependent on this capacitance is measured. Method according to Claim 1, characterized by the following method steps: • Adjustment of the first element ( 1 ) relative to the second element ( 9 ) in a first direction along a first axis (X-axis) until the measured capacitance or the measured variable dependent on this capacitance reaches a defined value and storing the associated actual position (x ₁ ) of the first element ( 1 ); Reversing the relative motion of the first and second elements ( 1 . 9 ), Adjusting the first element ( 1 ) relative to the second element ( 9 ) in a second direction along the first axis (X-axis) until the measured capacitance reaches a defined value or the measured variable dependent on this capacitance reaches a defined value and stores the associated actual position (x ₂ ) of the first element ( 1 ); • adjusting the first element ( 1 ) relative to the second element ( 9 ) in a first direction along a second axis (Y-axis) until the measured capacitance or the measured variable dependent on this capacitance reaches a defined value and storing the associated actual position (y ₁ ) of the first element ( 1 ); Reversing the relative motion of the first and second elements ( 1 . 9 ), Adjusting the first element ( 1 ) relative to the second element ( 9 ) in a second direction along the second axis (Y-axis) until the measured capacitance or the quantity dependent on this capacitance reaches a defined value and storing the associated actual position (y ₂ ) of the first element ( 1 ); Calculating the desired position (S) from the stored actual positions (x ₁ , x ₂ , y ₁ , y ₂ ) of the first element ( 1 ) relative to the second element ( 9 ). Method according to one of claims 1 or 2, characterized by the following method steps: • adjusting the first element ( 1 ) relative to the second element ( 9 ) along a first axis (X-axis) and storing the actual position (x ₁ ) of the first element ( 1 ) at which the measured capacitance is minimal or the measured variable dependent on this capacitance is minimal or maximal. • adjusting the first element ( 1 ) relative to the second element ( 9 ) along a second axis (Y-axis) and storing the actual position (y ₁ ) at which the measured capacitance is minimum or the measured variable dependent on this capacitance is minimum or maximum; Calculating the desired position (S) from the stored actual positions (x ₁ , y ₂ ) of the first element ( 1 ) relative to the second element ( 9 ). Method according to one of the preceding claims, characterized by the following method steps: • Adjustment of the first element ( 1 ) on a defined, preferably symmetrical, in particular circular, preferably around a center running, relative movement path ( 21 ) and storing a plurality of actual positions on the relative movement path ( 21 ) with associated measured capacitances or associated capacitance-dependent, measured variables; • Calculating the desired position (S) from the stored actual positions and the associated measured capacities or measured variables. Method according to one of the preceding claims, characterized in that the relative movement between the elements ( 1 . 9 ) is stopped as soon as contact between the elements ( 1 . 9 ) is detected. Method according to one of the preceding claims, characterized in that the axes (X, Y) along which the elements (X, Y) 1 . 9 ) are adjusted relative to each other, intersect and preferably correspond to the axes of movement of a machine tool. Method according to one of the preceding claims, characterized in that the first element ( 1 ) a tool, in particular an erosion electrode, and the second element ( 9 ) a workpiece, or the first element ( 1 ) a workpiece and the second element ( 9 ) is a tool, in particular an erosion electrode. Method according to one of the preceding claims, characterized in that the method is on a machine tool is carried out. Method according to one of the preceding claims, characterized in that between the elements ( 1 . 9 ) a dielectric, in particular a liquid and / or an electrolyte, preferably water, is provided. Device, in particular a machine tool, preferably designed for carrying out a method according to one of the preceding claims, for, in particular centric, aligning a first element ( 1 ) relative to a second element ( 9 ), the first element ( 1 ) relative to the second element ( 9 ) in at least two directions, in particular in two linearly independent directions (X-axis, Y-axis), is adjustable, wherein a desired position (S) of the first element ( 1 ) relative to the second element ( 9 ) by means of logic means on the basis of several by relative displacement of the elements ( 1 . 9 ) adjustable actual positions of the first element ( 1 ) relative to the second of the elements ( 9 ) and then the first element ( 1 ) relative to the second element ( 9 ) is adjustable to the desired position (S), characterized in that signal-conducting connected to the logic means means ( 19 ) for measuring an electrical capacitance of the first and second elements ( 1 . 9 ) formed electrical capacitor ( 12 ) or a quantity dependent on the capacitance, in particular during the relative displacement of the elements ( 1 . 9 ) are provided. Device according to claim 10, characterized in that the means ( 19 ) an LC resonant circuit ( 13 ), wherein the capacitor ( 12 ) of the LC resonant circuit ( 13 ) of the elements ( 1 . 9 ) is formed. Device according to one of claims 10 or 11, characterized in that means ( 19 ) for detecting a, in particular electrical, contact between the elements ( 1 . 9 ) are provided.