Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1989-12-15
1993-11-09
Shoop, Jr., William M.
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318625, G05B 1918
Patent
active
052606309
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
a. Field of the Invention
This invention relates to a numerical control apparatus and, more particularly, to a numerical control apparatus for controlling the rotational velocity of a plurality of spindles independently or simultaneously.
b. Description of the Related Art
Some machine tools such as lathes are equipped with a plurality of spindles. For example, a lathe for backface machining has two spindles in order to rotate a workpiece. Back-face machining is performed by setting a workpiece on one spindle automatically when machining using the other spindle is completed. Besides machining such as turning, lathes can apply other types of machining, such as boring and grooving. In such case, the tools themselves must be rotated, there are two tool rests, and the number of spindles is three, four or more.
In order to control the rotational velocities of a plurality of spindles, the practice in the prior art is to (i) provide a plurality of rpm command output units and a plurality of units for converting rpm commands into voltages and delivering these voltages to a spindle control amplifier, or (ii) change over one rpm command so that the command may be used to control any one of a plurality of spindles. However, these former methods require provision of a plurality of spindle control systems and therefore result in a large and costly apparatus. Such methods are not suited for the control of a number of spindles.
Further, with the latter method, an rpm command is issued for only one spindle at all times. Consequently, even if spindles are to be commanded to rotate at the same rpm, it is required that the command be changed over a plurality of times. As a result, operability is poor when controlling a number of spindles.
Accordingly, an object of the present invention is to provide a numerical control apparatus in which control of the rotation of a plurality of spindles is performed efficient fashion and at high speed, and in which it is possible to readily deal with a change in the number of spindles.
SUMMARY OF THE INVENTION
In order to solve the foregoing problems, the numerical control apparatus of the present invention comprises an NC data generating unit for generating NC data for the purpose of designating spindle rpm, switching unit, and memory unit provided correspondingly for each spindle for storing spindle rotational velocity, wherein one or more spindles and one spindle rotational velocity are designated by NC data, the designated spindle rotational velocity is stored via the switching unit in the memory unit corresponding to the designated spindles, and the corresponding spindles are controlled to rotate at the spindle rotational velocity stored in each memory unit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a functional block diagram of a numerical control apparatus according to the present invention, and
FIG. 2 is a block diagram of a numerical control apparatus according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a functional block diagram of a numerical control apparatus according to the present invention, in which numeral 1 denotes an NC data generating unit, 2 denotes a switching unit, 2a through 2n denote command transmission switches which are provided for each of the corresponding spindles, 3a through 3n denote memory units provided for each of the corresponding spindles, 4a through 4n denote converters provided for each of the corresponding memory units for converting rpm's into voltage data, 5a through 5n denote spindle drive amplifiers, and 6a through 6n denote spindle motors.
When the NC data generating unit 1 issues a command for one or more spindles and one spindle rotational velocity, the command transmission switches 2a through 2n are turned on, so that the contents in the memories 3a through 3n of the spindles commanded via the switches are updated by the commanded spindle rotational velocity. As a result, the rotation of the corresponding spindle motors 6a through 6n is controlled in accordance with the s
REFERENCES:
patent: 4692872 (1987-09-01), Kiya
patent: 4862380 (1989-08-01), Kawamura et al.
Iwagaya Takashi
Kurokawa Takashi
Fanuc Ltd.
Kim Helen
Shoop Jr. William M.
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