Data processing: measuring – calibrating – or testing – Measurement system – Time duration or rate
Reexamination Certificate
2002-12-10
2004-04-27
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system
Time duration or rate
C700S003000, C700S174000
Reexamination Certificate
active
06728657
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a machining time estimation apparatus for estimating the machining time of a numerical control (NC) machine tool by analyzing an NC program for controlling the drive mechanisms of the NC machine tool.
2. Description of the Prior Art
As a conventional machining time estimation apparatus, an apparatus disclosed in Japanese Unexamined Utility Model Publication No. 5-63749 is known. This machining time estimation apparatus comprises a machining program storage section, a program interpreting section, an axis feed speed data storage section, an axis movement time calculation section, an MST operation time calculation section, an addition section, an MST operation time data storage section, a general-purpose M-code operation time data storage section, etc.
The program interpreting section reads an NC program stored in an NC program storage section, block by block, and interprets its contents and transmits axis movement commands and MST commands serving as miscellaneous function operation commands so as to be distributed to the axis movement time calculation section and the MST operation time calculation section, respectively. The miscellaneous functions are functions commanded as M, S and T codes in a machining program. Usually, M codes relate to spindle normal/reverse rotation commands, tool change commands, etc., S codes relate to spindle rotation speed, and T codes relate to tool designation, for example.
The axis movement time calculation section obtains the amount of axis movement on the basis of the axis movement commands transmitted from the program interpreting section, calculates an axis movement time on the basis of the obtained amount of the axis movement and the axis feed speed data stored in the axis feed speed data storage section, and transmits the time to the addition section.
On the other hand, the MST operation time calculation section reads applicable data from MST operation time data preset at each operation and stored in the MST operation time data storage section and the general-purpose M-code operation time data storage section on the basis of the MST commands transmitted from the program interpreting section and transmits the MST operation time obtained from the read data to the addition section. General-purpose M codes are codes allocated so as to be usable as desired by a user. Data on the operation time of the function set by the user is preset and stored in the general-purpose M-code operation time data storage section.
The addition section adds each operation time transmitted from the axis movement time calculation section and the MST operation time calculation section to calculate a machining time.
Hence, with this machining time estimation apparatus, the time required for applicable machining (machining time) can be known in advance from a machining program to be used for the machining, whereby it is possible to devise a detailed machining plan for a product to be obtained by the machining.
However, in actual practice, the axis movement time and the MST operation time are different depending on the kind of a machine tool and the state of the machine tool. In particular, the MST operation time changes frequently depending on a lapse of time and the incessantly changing state of the machine tool. For example, regarding the rotation of the spindle, the time required to reach its commanded rotation speed from the spindle stop state differs depending on the weight of a workpiece to be machined and the commanded rotation speed. In addition, when a tool is indexed to a machining position by swiveling the turret, the operation time differs depending on the interval between the currently indexed tool and the tool to be indexed next. Furthermore, the operation time changes depending on the change in the frictional resistance of the sliding portion. When the sliding portion is driven by hydraulic or pneumatic pressure, the operation time changes depending on the state of the pressure.
In the above-mentioned conventional machining time estimation apparatus, when the MST operation time is calculated, applicable operation time data is read from the operation time data preset as a fixed value regarding each MST operation and stored in the storage section, and the data is allocated as the MST operation time. Hence, when the actual MST operation time changes depending on a lapse of time and the incessantly changing state of the machine tool as described above, a problem of being incapable of accurate machining time calculation is caused.
For this reason, when a machining time is calculated by the above-mentioned conventional machining time estimation apparatus and when machining is carried out in accordance with a machining plan devised on the basis of the calculated machining times, the machining plan is deranged.
Accordingly, the present invention is intended to provide a machining time estimation apparatus capable of accurate machining time calculation.
SUMMARY OF THE INVENTION
The present invention for solving the above-mentioned problems relates to a machining time estimation apparatus for an NC machine tool, which estimates the machining time of the NC machine tool, comprising:
a program storage section for storing an NC program formed of a plurality of command blocks,
a program analysis section for reading the NC program stored in the program storage section, for analyzing the NC program, block by block, and for outputting a control signal on the basis of the result of the analysis,
a drive control section for receiving the control signal output from the program analysis section and for controlling the operation of each drive mechanism concerned with the axis movement and miscellaneous functions of the NC machine tool on the basis of the received control signal, wherein the machining time estimation apparatus further comprises:
a database for storing the actual operation time data of the drive mechanism concerned with the miscellaneous functions,
actual operation time calculation means for calculating the actual operation time of the drive mechanism concerned with at least the miscellaneous functions on the basis of the control signal output from the program analysis section and an operation completion signal obtained from the drive mechanism and for updating the data stored in the database by using data on the calculated actual operation time, and
operation time estimation means for analyzing each block of the NC program stored in the program storage section, for calculating the estimated operation time of the drive mechanism concerned with the axis movement on the basis of the result of the analysis, for estimating the operation time of the drive mechanism concerned with the miscellaneous functions by searching the database on the basis of the result of the analysis, for calculating the estimated operation time of each block on the basis of the estimated operation time of the drive mechanism concerned with the axis movement and the estimated operation time of the drive mechanism concerned with the miscellaneous functions, and for calculating the estimated machining time by totalizing the estimated operation time of each block.
With this machining time estimation apparatus, each time actual machining is carried out on the machine tool, the actual operation time of the drive mechanism concerned with at least the miscellaneous functions is calculated by the actual operation time calculation means. The data stored in the database is updated by the data on the calculated actual operation time. By this updating process, the reliability of the data stored in the database is enhanced.
The miscellaneous functions are functions other than axis movement functions and they are commanded as M, S and T codes in an NC program. Usually, M codes relate to spindle normal/reverse rotation commands, tool change commands, etc., S codes relate to spindle rotation speed, and T codes relate to tool designation, for example. The drive mechanisms for the miscellaneous functions are a mechanism for r
Barlow John
Le John
Mori Seiki Co. Ltd.
Westerman Hattori Daniels & Adrian LLP
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