Boots – shoes – and leggings
Patent
1987-02-24
1989-03-28
Smith, Jerry
Boots, shoes, and leggings
318571, 318696, 82118, G05B 1300
Patent
active
048170070
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to machine tool control systems.
2. Description of the Related Art
In recent years, many forms of machine tool including computer numerical control (CNC) systems have been developed. In such machine tools, a workpiece is rotated and a tool moved in two mutually perpendicular directions by stepping motors controlled to produce a required workpiece profile from data defining the required profile and held in digital form in a control system. In such CNC machine tools, however, the motor which rotates the workpiece is not controlled by the control unit; rather it is rotated independently and a workpiece position transducer is used to feed to the control system a signal corresponding to the angular position of the workpiece.
It is a disadvantage of such CNC systems that they have to perform a feedback function to account for variations in the speed of workpiece drive. This has the disadvantage that valuable data storage space and computing time are taken in performing this function, so reducing the overall machining speed.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a machine tool comprising an electric motor for rotating a workpiece from a datum angulor position, a tool for machining said rotating workpiece, a tool drive connected to said tool for moving said tool to produce a required surface profile on said rotating workpiece, a control system, a store included in the control system, connected to the tool drive and containing data defining said required surface profile, an output device included in the control system and connected to the workpiece motor, the tool drive and the store to output and to the workpiece motor a succession of step signals to rotate the workpiece motor and the workpiece, and, for each step signal, to output to the tool drive from the stored data, a tool drive signal corresponding to a required tool position to machine said required surface profile, at the angular position of the workpiece holder determined by the number of step signals outputted since a datum angular position of the workpiece motor.
Thus, by the workpiece motor from step signals produced from the tool system, the control system is not required to deal with feedback signals from the workpiece motor.
The following is a more detailed description of one embodiment of the invention, by way of example, reference being made to the accompanying drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic block diagram of a machine tool and of a control system for controlling the machine tool,
FIGS. 2A, 2B, 2C, 2D and 2E are views of five interior cross-sectional profiles of bearings when can be manufactured using the machine tool of FIG. 1, and
FIGS. 3A, 3B, 3C and 3D are views of four interior axial profiles of bearings which can be manufactured using the machine tool of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIG. 1, the machine tool comprises a workpiece stepping motor 10 which rotates a workpiece 11 (which will be described in more detail below). The workpiece motor 10 may drive the workpiece 11 directly, as shown, or may drive it through appropriate gearing or belting. A datum device 17 is connected to the workpiece motor 10 and produces a datum signal when the workpiece motor passes a predetermined angular position.
A tool holder 12 is mounted for pivotal movement on a post 13 which is mounted on a carriage 14. The pivot axis 15 of the tool holder is normal to the axis of rotation of the workpiece 11.
A tool 16 is mounted at one end of the tool holder 12 and the other end of the tool holder 12 is connected to a tool drive 18, which is also mounted on the carriage 14 and is for moving the tool holder 12 about the pivot.
The tool drive 18 is under the control of a tool drive control system 19 which receives feedback signals from a tool position transducer 20. The operation of these parts will be described in more detail below.
The carriage 14 is mount
REFERENCES:
patent: 4031368 (1977-06-01), Colding et al.
patent: 4038890 (1977-08-01), Winget
patent: 4237408 (1980-12-01), Frecka
patent: 4401930 (1983-08-01), Kato et al.
patent: 4468741 (1984-08-01), Simonton
patent: 4694401 (1987-09-01), Higuchi
AE PLC
MacDonald Allen
Smith Jerry
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