Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2001-12-21
2004-11-16
Paladini, Albert W. (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S176000, C074S816000
Reexamination Certificate
active
06819973
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to indication of offset values of a cutting tool in a control apparatus which is employed in a cutting machine (specifically an NC lathe or machining center) for performing various cutting according to numerical control.
Particularly, the present invention relates to the control apparatus for the cutting machine in which a turret turns around a B-axis so that cutting process can be conducted at an arbitrary position (capable of indexing at the arbitrary position). Further, the present invention relates to the control apparatus for the cutting machine in which the cutting tool can rotate around the tool axis.
2. Description of the Related Art
(1) In a conventional control apparatus for the cutting machine based on the numerical control, an offset value of a cutting edge of the cutting tool has been indicated, and numerical values for conducting the cutting have been inputted referring to the values. There have been some cutting machines such as the NC lathe and machining center, in which the cutting tool turns around the B-axis. Here, the B-axis is a reference axis regulated by JIS which means an axis perpendicular to both the X-axis and Z-axis of the turret
1
as shown in FIG.
1
.
(2) There have been heretofore those control apparatuses in which the offset values are indicated on the bases of coordinate axes relative to the turret, when the turret has turned with respect to the B-axis. For example, in the case where the offset values of the cutting tool have been already determined, the same offset values are indicated at any positions where the turret has turned. In the case where the offset values are (X
100
, Z
25
) for example, even though the turret has turned by 90 degree, the offset values have been indicated as (X
100
, Z
25
).
In this case, an operator must calculate for himself the offset values according to the position after the turn, and input the numerical values based on the calculated values. This has been a heavy task to the operator, and also there has been a risk of miscalculation.
Particularly, because the X-axis offset value is indicated by diameter, when the turret has turned by 90 degree, the offset value must be twice as much as the Z-axis value and a half of the X-axis value, and the calculation has been annoying. In the case where the turning angle is 40 degree or so, it has been impossible to convert the offset values by mental arithmetic.
(3) Meanwhile, there is Japanese Publication No. JP-A-2000-141164 of unexamined Patent Application which relates to a cutting machine in which the turret can turn around the B-axis and tool compensation values (the offset values) of a cutting edge of the tool are not indicated relative to the turret. However, in this patent application, the tool compensation values corresponding to predetermined turning angles, such as the turns of the turret by every 90 degree, are indicated. Therefore, in the art disclosed in this patent application, the tool compensation values (the offset values) when the turret has turned to arbitrary angles cannot be indicated. Moreover, there has been a problem that if the tool compensation values at every turning angle are to be stored, it will cause an overload of a memory section in the control apparatus.
(4) Further, the above-described problems have existed also, when the cutting tool is rotated around the tool axis.
SUMMARY OF THE INVENTION
In view of the above, it is an object of the invention to provide a control apparatus for a cutting machine having a turret which can turn to arbitrary positions, in which offset values on coordinates relative to the cutting machine are indicated, regardless of the position of the turret, and an operator need not calculate the offset values in the cutting process.
It is another object of the invention that the offset values with respect to arbitrary turning angles of the turret can be indicated, while reducing load on a memory section in the control apparatus.
It is a further object of the invention to make it unnecessary to convert the offset values of a cutting edge of the tool after rotation, even in a control apparatus for a cutting machine which can rotate to an arbitrary position relative to a tool axis.
(1) This invention relates to a control apparatus for a cutting machine adapted to conduct numerical control and having a turret
1
which can be turned to arbitrary positions, characterized in that an X-axis offset value (&Dgr;X) and a Z-axis offset value (&Dgr;Z) of a cutting edge
3
of a cutting tool when the turret
1
has been turned to an arbitrary angle are converted to values on coordinates relative to the cutting machine, and indicated.
Here, the X-axis offset value (&Dgr;X) and the Z-axis offset value (&Dgr;Z) are defined as values for compensating a difference between a position of the cutting edge of the tool assumed on a prepared cutting program and an actual position of the cutting edge, when they are different from each other. Specifically, on coordinates defined by two axes (the X-axis and the Z-axis) perpendicular to each other concerning the positions of the cutting edge of the tool, the value twice as much as the X-axis value (indication by diameter) is referred to as “the X-axis offset value”, and the Z-axis value is referred to as “the Z-axis offset value”.
In the conventional cutting machine, the same offset values have been indicated even when the turret
1
has turned around the B-axis. This is because the offset values relative to the turret
1
have been indicated. On the other hand, in this invention, the offset values are not relative to the turret
1
, but always indicated as points on the coordinates relative to the cutting machine, at any position where the turret
1
has turned. This facilitates calculation of compensation values to be inputted in the cutting process. For example, in an embodiment as shown in
FIGS. 1
to
3
, an initial position is set at a position of −90 degree of the turret
1
in
FIG. 1
, and the offset values after the turret
1
has turned are indicated on the basis of this coordinate.
Also in this invention, at every turn of the turret
1
, the offset values are converted according to its turning angle (&agr;) and indicated. Accordingly, the memory section of the control apparatus need not store the offset values at every turning angle, and thus, the load with respect to a capacity for memory will be decreased.
(2) One of desirable embodiments of the invention is the above described control apparatus, characterized in that wear compensation values (&Dgr;Xt, &Dgr;Zt) are indicated in relation to the X-axis offset value (&Dgr;X) and the Z-axis offset value (&Dgr;Z). Further, this control apparatus is preferably in such a form that the inputted wear compensation values (&Dgr;Xt, &Dgr;Zt) may be indicated in order of the input.
An ordinary cutting process is not completed by a single cutting, but several cuttings must be conducted. This is done so as to avoid cutting too much when the cutting is conducted at a time, and so as to compensate for wear of the cutting edge of the tool.
When such several cuttings are conducted, the operator measures sizes of a workpiece to be cut after the cutting process, and further cuts a portion exceeding a preset value by inputting the wear compensation values. In this case, the wear compensation values are inputted with reference to the X-axis offset value (&Dgr;X) and the Z-axis offset value (&Dgr;Z) which are indicated. However, the wear compensation values to be inputted at a second and successive cuttings must be set with reference to the wear compensation values which have been inputted at a previous cutting, so that a further cutting may be conducted in addition to the inputted values.
For example, in case where the offset value is (X 100.0) and the wear compensation value at a first cutting is (−0.1) in cutting an outer periphery, the compensation value at the second cutting must be smaller than (−0.1). If the compensation value of (−0.05)
Nakahira Hiroki
Ono Katsuaki
Kosowski Alexander
Mori Seiki Co. Ltd.
Osha & May L.L.P.
Paladini Albert W.
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