GB2094506A

GB2094506A - Control of production equipment

Info

Publication number: GB2094506A
Application number: GB8203119A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-02-05
Filing date: 1982-02-03
Publication date: 1982-09-15
Also published as: GB2094506B

Abstract

For production equipment having a movable operating element and manually actuated drives for effecting movement of the operating element, a numerical control system is programmed with data defining a limit contour and is effective to provide an over-ride limit on the movement of the operating element which is permitted by manual actuation of the drives. For example, in a lathe with machine tool 12 and a chuck 20 holding a workpiece 10, the limit contour L, L1 may be spaced slightly from the desired final profile P of the workpiece, requiring a final machining operation which may be carried out fully automatically or fully manually. <IMAGE>

Description

SPECIFICATION Control of production equipment This invention reiates to production equipment and is generally applicable to any such equipment having an operating element which in use executes controlled movements relative to a workpiece. Examples of such an element include a welding head, a paint spraying head, or a machining tool such as that of a lathe.

In such equipment, it is known to provide a numerical control system which may be programmed according to the movements which the operating element is required to execute throughout its production cycle, and the system then controls drives of the operating element to displace it according to those required movements. In the case of a lathe, for example, the system may be programmed according to the shape or profile of a part to be turned, and it then controls drives of the lathe tool so that the part will be turned automatically to its required profile.

Generally human supervision is still required of such automatically operating equipment, but the need for a skilled operator is removed and this is not found to be wholly desirable in all cases.

In accordance with this invention there is provided, in or for a production equipment having a movable operating element and manually actuated drives for effecting movement of the operating element, a numerical control system programmed or programmable with data defining a limit contour and effective to provide an override limit on the movement of the operating element which is permitted by manual actuation of said -drives. Thus the operator may exercise his skills in effecting manual control but the programmed limit contour prevents manual movement of the operating element to forbidden positions.

An embodiment of this invention will now be described, by way of example only, with reference to the accompanying drawing, the single figure of which is a diagrammatic longitudinal section through a part being turned on a lathe, to explain the nature of the control effected by the data control system associated with the lathe.

The lathe comprises a conventional construction and arrangement and includes a chuck 20 (shown diagrammatically) for holding and rotating a part 10 to be turned, and a tool 12.

The tool is mounted in a holder 14 (also shown diagrammatically) having associated with it a first drive for effecting movement of the tool parallel to the lathe axis Z and a second drive for effecting movement of the tool in the radial direction X.

Manual controls such as handwheels are provided for operating these drives to correspondingly move the tool 12.

The part 10 to be turned is shown with a required final profile P (shown on the iower half of the part only). A numerical control system associated with the lathe is programmable with a limit profile, which in the case shown is at L, spaced slightly from the required profile P: instead, the limit profile L may correspond exactly with the required profile P. The control system controls the tool drives such that the operator may have full manual control over movements of the tool so long as the latter is positioned outside the limit profile L, but it will override the manual controls should the operator attempt, for example accidentally, to move the tool beyond the profile L (i.e. out of the hatched zone M).Thus, each manual control may be arranged to freewheel when the tool reaches the profile L, requiring the operator to run that control in the opposite direction to return the tool to the permitted zone and to manual control.

The system may be programmed for a limit profile which includes portions of increasing and/or decreasing radii in the axial direction Z, as indicated by the limit profile L for increasing and further limit profile L, for decreasing radii.

The system described above is operative regardless of the tool orientation, which will be adjusted to whatever is appropriate for the part being turned. Also, the system may be arranged to control the rotational speed according to the radial position of the tool so that the peripheral speed at the tool point remains substantially constant. The control system preferably incorporates a facility for comparing an actually machined diameterwith an expected corresponding diameter, and effecting a correction on the programmed profile accordingly.

The control system in the embodiment shown is arranged so that certain operaticns can be carried out fully automatically, under program control. Thus for example, the part 10 shown includes a screw-thread portion 1 0a at its end, and firstly this portion is turned under fully automatic control and thereafter the system may be switched to manual control (with the over-ride of profile L) to machine the part to the profile L.

Finally, the system may be switched again to fully automatic control to machine down to the required final profile P.

The system may be arranged for carrying out the entire machining operation fully automatically under full data control, but also arranged for optionally switching if desired to the manual control with limit over-ride mode described above. In particular, the system may be switched between its fully automatic and manual modes whilst a part is in course of machining. Where the system is switched from manual to automatic, the feed (driven movement of tool in axial direction Z) may be continued at a previously programmed rate, or if required by the operator it may be continued at the previous manual rate (as measured by the system during the period of manual mode).

The system may include a visual display for displaying the required final profile and the actual current profile and other data, e.g. tool position.

The lathe may include two handwheels for controlling movement of the tool along the respective X and Z axes, or it may include one handwheel for both axes and a selector for selecting between the two. Once the part has been turned to the profile L, then instead of finishing it automatically to the final profile P, it may be finished under a fully manual mode. The system is preferably arranged to effect offset correction in the axial direction Z in respect of axial position or length of the blank part to be turned.

Claims

1. In or for a production equipment having a movable operating element and manually actuated drives for effecting movement of the operating element, a numerical control system programmed or programmable with data defining a limit contour and effective to provide an override limit on the movement of the operating element which is permitted by manual fluctuation of said drives.

2. A numerical control system according to claim 1, programmed or programmable to carry out movements of the operating element fully automatically, and switchable between fully automatic mode and the manual mode with override limit.

3. A numerical control system according to claim 2, arranged for movement of the operating element relative to the workpiece to continue at a previously programmed rate upon being switched to the automatic mode.

4. A numerical control system according to claim 2, arranged or selectively controllable for movement of the operating element relative to the workpiece to continue at the previous manual rate upon being switched to the automatic mode.

5. A numerical control system according to any preceding claim, including means to sense the actual position to which the operating element has moved and comparing this position with that expected according to commands given to the drives of the operating element, and accordingly effecting any necessary correction on the programmed data defining the limit contour.

6. A numerical control system according to any preceding claim, programmed or programmable for at least a component of relative velocity between the operating element and workpiece to vary according to the relative positions of operating element and workpiece.

7. A numerical control system according to any preceding claim, in or for a machining equipment (for example a lathe), arranged for the limit contour to correspond exactly with the desired final profile of the workpiece being machined.

8. A numerical control system according to any preceding claim, in or for a machining equipment (for example a lathe), arranged or selectively controllable for the limit contour to be spaced slightly from the desired final profile of the workpiece being machined, requiring a finishing machining operation to be performed on the workpiece after it has been machine to said limit contour.

9. A numerical control system as claimed in claim 8, programmed or programmable with data defining movements of the operating element (machining tool) for carrying out said finishing operation automatically.

10. A numerical control system as claimed in claim 8 or 9, controllable for carrying out said finishing operation fully manually.

1 A numerical control system in or for a lathe, substantially as herein described with reference to the accompanying drawing.