Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Reexamination Certificate
2002-03-12
2004-05-04
Leykin, Rita (Department: 2837)
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
C318S569000, C318S573000
Reexamination Certificate
active
06731090
ABSTRACT:
TECHNICAL FIELD
This invention relates to a numerical value control processing method and a numerical value control system for a machine tool.
BACKGROUND ART
Along the increasing complexity and higher precision in the shapes of products, the frequency of using a CAD (Computer Aided Design) system and a CAM (Computer Aided Manufacturing) system has increased in order to efficiently prepare work programs of numerical value control units for machine tools. In the work programs prepared by using the CAD/CAM systems, there is a case where command blocks of short move quantity like a few millimeters or less are continuously disposed at portions like curves.
According to a conventional general numerical value control unit, a work program analyzing section analyzes the contents of a program commanded by a block, each time when the command information is read by one block. Then, a machine control section controls a machine movable part by carrying out interpolation and acceleration/deceleration processing.
In the case of a normal work program, a numerical value control unit analyzes a program in advance in the work program analyzing section, and a status that a result of the analysis is stored in a data buffer is maintained. However, in the case of a work program in which command blocks of short move quantity like a few millimeters or less are continuously disposed, the machine control section executes each command block faster than the work program analyzing section analyzes the program. As a result, there occurs such a phenomenon that the data inside the data buffer is kept consumed, and the data becomes empty in the data buffer.
As explained above, when a short command block immediately before has been executed in a short time, the next command is not in time. When the numerical value control unit cannot analyze the program in time, the forwarding of a tool between the blocks stops temporarily, and a cutter mark is attached to a product. This brings about the aggravation of the product quality. Further, this also gives bad effects to the production efficiency, such as the cycle time becomes longer.
For avoiding the temporary stopping of the tool between the blocks, according to the conventional numerical value control unit, it is necessary to lower the speed of forwarding the tool in line with the program analysis capacity of the numerical value control unit. This results in not being able to achieve the high-speed processing performance of the machine tool.
In order to solve the above problems, numerical value control (NC) system has been proposed as disclosed in Japanese Patent Application Laid-open Publication No. 63-26707. This numerical value control system will be explained below with reference to FIG.
13
. This numerical value control system comprises a numerical value control unit
10
, a buffer memory unit
12
installed separately from or attached to the numerical value control unit
10
, for storing NC work data, a work program supplying unit
14
for supplying a work program, a high-speed NC data preparing unit
16
for converting a predetermined NC work data into a high-speed NC work data according to a high-speed work command from the NC work program supplied from the work program supplying unit
14
, and a group of driving motors
18
that are operated according to NC work command data supplied from the numerical value control unit
10
.
The work program supplying unit
14
and the high-speed NC data preparing unit
16
are connected to each other via an interface unit
20
. Similarly, the high-speed NC data preparing unit
16
and the buffer memory unit
12
are connected to each other via a similar interface unit. The high-speed NC data preparing unit
16
has a data receiving section
24
, a high-speed NC data processing section
26
, and a data transmitting section
28
, as shown in FIG.
14
.
A work program supplied from the work program supplying unit
14
includes both an NC work command for executing an NC work in a normal or standard speed mode and an NC work command for executing an NC work in a high-speed mode. When an NC work program that includes a high-speed work command has been supplied to the data receiving section
24
of the high-speed NC data preparing unit
16
, the high-speed NC data preparing unit
16
transmits an NC command data to the data transmitting section
28
via the high-speed NC data processing section
26
or by bypassing the high-speed NC data processing section
26
. In the case of a high-speed mode, the high-speed NC data processing section
26
interpolates the NC command data, and converts the data into a binary move command data that can be directly supplied to a servo control section within the numerical value control unit
10
.
The high-speed NC data preparing unit
16
is a unit which prepares the data that can be directly supplied to the servo control section within the numerical value control unit
10
, in advance at high speed by a processing unit that is separate from the numerical value control unit
10
. This system is a numerical value control system that can omit all the interpolation processing of the numerical value control unit
10
. Based on this arrangement, it is possible to carry out the automatic processing with high efficiency.
However, when a work program has continuous command blocks of short move quantity, there is a case where even the above numerical value control system cannot obtain a target tool forwarding speed or a target work rotation speed by maintaining sufficient processing precision. Consequently, there is a limit to obtaining more increase in the processing speed of a machine tool.
This invention has been achieved in order to solve the above problems. The invention has an object of providing a numerical value control processing method and a numerical value control system capable of further increasing the processing speed of a machine tool, in the execution of a work program that has continuous command blocks of short move quantity.
DISCLOSURE OF THE INVENTION
This invention can provide a numerical value control system that controls a machine tool, by calculating a move command from a work program or a work data for a numerical value control unit, and directly inputting the move command to a servo control section within the numerical value control unit from the outside of the numerical value control unit, Wherein the numerical value control system comprises at the outside of the numerical value control unit: an analyzing unit which analyzes a work program or a work data; and an interpolating unit which carries out interpolation for each axis in a position control period of the servo control section based on output information from the analyzing unit and cut conditions, whereby the numerical value control system controls a machine tool by directly inputting a move command of a binary format prepared in advance by the interpolating unit, to the servo control section within the numerical value control unit.
Accordingly, at the outside of the numerical value control unit, it is possible to carry out interpolation in a position control period of the servo system shorter than a machine control period of the numerical value control unit. As a result, it is possible to further increase the processing speed of the machine tool, in the execution of a work program that has continuous command blocks of short move quantity.
Further, this invention can provide a numerical value control system that comprises at the outside of the numerical value control unit: a speed information generating unit which generates speed information per unit time in advance by carrying out acceleration/deceleration processing to interpolation data output from the interpolating unit, whereby the numerical value control system controls a machine tool by directly inputting a move command of a binary format including the speed information prepared in advance by the speed information generating unit, to the servo control section within the numerical value control unit.
Accordingly, it is possible to carry out not only the analysis p
Mizutani Kazuo
Tanaka Takahisa
Leykin Rita
Mitsubishi Denki & Kabushiki Kaisha
Sughrue & Mion, PLLC
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