Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1995-11-02
1998-04-21
Shoop, Jr., William M.
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318632, 318560, 318689, G05B 19408
Patent
active
057421404
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a machine tool, and particularly to a numerical-control machine tool in which a plurality of backlash compensation values are set
BACKGROUND ART
A numerical-control machine tool has its feed stages or tables moved and positioned along the positioning axis by means of feed screws. The feed screws are driven by servo motors which are controlled by a numerical control equipment
There has been proposed the compensation for the backlash of these feed screws.
For example, there has been proposed a scheme of compensation in which one backlash compensation register is provided for one positioning axis, a backlash compensation value is set in each register, and the backlash of feed screws is compensated based on the backlash compensation values.
The backlash compensation value is preset based on the degree of backlash of the feed screw. The degree of backlash is a mean value of actually measured values.
However, a numerical-control machine tool with the provision of the above-mentioned backlash compensation resistors behaves to have slightly different positioning errors between the high-speed feed mode and the low-speed feed mode. The reason for that is the occurrence of a different degree of backlash depending on the kind of mode and feed rate.
On this account, there is a drawback of degraded machining accuracy.
Particularly, recent numerical-control machine tools operate at increased feed rates, which results in an increased difference between feed rates of the high-speed feed mode and low-speed feed mode, and a resulting difference of positioning errors adversely affect the machining accuracy.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a numerical-control machine tool capable of compensating the backlash depending on the kind of mode and feed rate.
The first of the present invention resides in a numerical-control machine tool characterized in the provision of a plurality of backlash compensation registers for one positioning axis.
The second of the present invention resides in a numerical-control machine tool characterized in the provision of memory means of backlash compensation values for each of at least one positioning axis, with each backlash compensation value memory means storing a plurality of backlash compensation values in correspondence to modes.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a front view of the numerical-control machine tool based on a preferred embodiment of this invention.
FIG. 2 is a side view of the numerical-control machine tool shown in FIG. 1.
FIG. 3 is a block diagram showing the electrical connection in the numerical-control machine tool shown in FIG. 1.
FIG. 4 is a diagram used to explain the backlash compensation for the first feed screw.
FIG. 5 is a front view of the operator's panel of the numerical-control machine tool shown in FIG. 1.
FIG. 6 is a diagram used to explain the feeding in the X-axis direction and Y-axis direction.
FIG. 7 is a diagram used to explain the feeding in the X-axis direction and Z-axis direction.
BEST MODE FOR CARRYING OUT THE INVENTION
The numerical-control machine tool based on a preferred embodiment of this invention will be explained with reference to FIG. 1 through FIG. 7.
This numerical-control machine tool is a vertical machining center, and it includes a machine tool main body 1, a numerical control equipment 2, an operator's panel 3, and a dam file on-line system 4.
Machine Tool Main Body 1
The machine tool main body 1 will be explained with reference to FIG. 1 and FIG. 2.
The machine tool main body 1 includes a bed 11, a first table 12, a second table 13, a column 14, a spindle head 15, a first through third servo motors 16-18, a first through third feed screws 19-21, a first through third nuts 22-24, an automatic tool changer 25, a tool magazine 26, and a first through third mils 13a, 11a and 14a.
The first servo motor 16 and first rail 13a are fixed on the second table 13. The first table 12 is fitted movably in the X-axis direction relative to the
REFERENCES:
patent: 4510427 (1985-04-01), Nozawa et al.
patent: 5021941 (1991-06-01), Ford et al.
Kananen Ronald P.
Kitamura Machinery Co. Ltd.
Lockett Kim
Shoop Jr. William M.
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