Measuring and testing – Vehicle chassis – Steering
Reexamination Certificate
2002-10-11
2004-12-28
Le, Dang (Department: 2834)
Measuring and testing
Vehicle chassis
Steering
C279S004020
Reexamination Certificate
active
06834539
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The invention relates to a rotary machine element in which at least one functional part performs movements into nominal stop positions or into mechanical terminal stop positions which are functionally related and whose individual actual position values can be detected independent from one another with at least one position sensor. The invention further relates to a method for detecting position values of at least one functional part of such a rotary machine element.
2. Description of the Related Art
The alignment and clamping of workpieces, in particular, of crankshafts and camshafts, is carried out generally by hydraulically actuated chucks as a rotary machine element. In this connection, the workpiece can be received in a centered or floating arrangement by the chuck. Generally, the chuck comprises, dependent on the workpiece arrangement, several functions which can be carried out during the clamping process usually only in a temporal sequence one after another. Such functions are, for example, centering, clamping, as well as radial, axial, and rotary alignment of the workpiece. These functions are carried out by the corresponding functional parts, such as centering tips, alignment elements, and clamping elements. The functional states are monitored by control functions, for example, recognition of the workpiece type, control whether a workpiece is present or absent, or the like. During the clamping process, mechanical stop positions are conventionally present in the chuck, for example, when the clamping jaws or the centering tip impact on the workpiece. These stop positions are nominal positions which result from the workpiece geometry, for example, the clamping diameter. Further stop positions result when the maximum stroke of the individual chuck functions is reached, dependent on the mechanical chuck configuration, i.e., in the end position of the stroke, respectively. These stop positions are the terminal stop positions.
For controlling the different stop positions the respective mechanical movement of a functional part is coupled conventionally to one or more control rods whose positions are controlled by means of contactless proximity switches in combination with adjusting cams. Since particularly during alignment and clamping of crankshafts and camshafts a plurality of these chuck functions are necessary, numerous such proximity switches are required accordingly. The adjusting expenditure of these terminal proximity switches is high because the switching positions of each individual stop position must be adjusted by the adjusting cams. One proximity switch is thus required for each stop position. They must be adjusted with a relatively high precision. This high adjusting sensitivity, however, can result in faulty messages when vibrations occur, for example, in the case of residual imbalance of a lathe, as a result of machining vibrations on milling machines, or as a result of unavoidable concentricity deviations of the adjusting cams.
A further problem occurs when the stop positions to be controlled are changed as a result of, for example, workpiece dimensions which are not constant or a different type of workpiece. In this situation, the switching positions must be manually corrected or adjusted, which results in a cost-intensive downtime of the machine, maintenance work, repairs, and adjusting work.
A further disadvantage of conventionally employed control devices of a chuck resides in that a safe and reliable course of the functions is carried out serially and therefore is time-intensive with regard to machine cycles. For example, only after checking that the nominal position of a function has been reached, the next function is initiated. With this method it is prevented that, for example, clamping of the workpiece begins already during an accidentally delayed alignment movement. The mechanical position of a chuck function moreover is known to the control device only in those positions where the terminal proximity switches are provided. Intermediate positions between the individual terminal proximity switches are not detected.
Chucks are known tram DE 200 12 080 in which the mechanical position of the piston rod is detected by a control system based on magnetostrictive sensors. The position sensors are used in analogy to terminal proximity switches. i.e., the nominal positions provided during the course of the function or the terminal stop positions are controlled. Additional functions, for example, NC-controlled (NC=numerical control) moving of the chuck functions between the stop positions, measuring, checking, or moving for determining a reference point, are not realized.
Also, a servo device is known (DE 199 54 634) which enables detection of the respective position of the clamping piston by induction. This system is also used only for controlling the nominal positions or the terminal stop positions.
SUMMARY OF INVENTION
It is an object of the present invention to configure the rotary machine element of the aforementioned kind and the method of the aforementioned kind such that in a constructively simple way the functional part can be monitored with high precision.
In accordance with the present invention, this is achieved in regard to the rotary machine element in that the position sensor is located within a control and/or regulating path between the functional part and an NC-control which path is active in positions between the nominal stop positions and/or the mechanical terminal stop positions.
In accordance with the present invention, this is furthermore achieved in regard to the method in that the actual position values of the functional parts are detected and, based thereon, the speed and acceleration of the functional parts is determined by means of the NC-control.
The rotary machine element according to the invention is characterized in that the position sensor is located in a control and/or regulating path between the functional part and the NC-control. The control and/or regulating path (for short “control path”) is active in positions between the nominal stop positions and/or the mechanical terminal stop positions. The position sensor enables efficient diagnostic methods particularly in the nominal position or in the mechanical terminal stop position. Procedures for a simplified detection or determination of the nominal position, also referred to as reference point methods, are enabled by the position sensor. The control and regulating function is enabled by a continuous and highly precise measurement of the actual position of the functional part.
The determination of the actual position value of the functional part enables with high precision the determination of speed and acceleration. Also, travel distances, speeds, and accelerations for the functional part can be defined. When the rotary machine element has several functional parts, the travel distances, speeds, and accelerations can be defined for each functional part individually.
The movements of the individual functional parts which are functionally correlated with one another are carried out in a precise relation to one another. The travel distances, speeds, and accelerations for each functional part are advantageously programmed, processed, and saved in data processing devices (computer) or in numerical control devices (NC-devices).
By employing the position sensor and by employing corresponding software programs and data processing devices (computers), these functions can be measured, checked, monitored, and controlled, and combinations of these tasks can be carried out. Processing of data and transmission of required information to peripheral devices is carried out advantageously by software.
The measuring of the actual position values by means of the position sensor is advantageously a length measurement. In this case, the respective functional part of the machine element according to the invention performs an axial movement which is detected by the position sensor.
It is also possible that the measurement of the actual position
Gebr. Heller Maschinenfabrik GmbH
Huckett Gudrun E.
Le Dang
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