GB2117284A - Control of production equipment - Google Patents

Abstract

In, for example, a lathe having a numerical control system which displays co-ordinates of the tool tip position, data as to the offset of the tool tip (12), relative to a datum on the tool holder (10), is written into the system by actuating the manual drive for the tool holder, when these drives are disabled from driving that holder and when the tool tip is touching a known-dimension workpiece (14), the manual drive serving to drive the display until a value is displayed (say for the X-axis position) corresponding to the known dimension (say the radius) of the workpiece. <IMAGE>

Description

SPECIFICATION Control of production equipment This invention relates to production equipment having an operating element, for example a lathe having a machining tool, which in use executes controlled movements relative to a workpiece.

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 example of a lathe, the machining tool is removably held in a tool holder. The numerical control system is generally arranged to give numerical displays of the co-ordinates of the tool holder position, but this numerical data requires modification (according to the offset of the tool tip from the tool holder position) if it is to give directly the actual tool tip position. Hitherto, this has been carried out by physically measuring the offset of the tool tip from the datum on the tool holder (e.g.

measuring tool length), then keying this into the control system for the system to subtract this measurement from the displayed data and modify the latter accordingly, so that the control system is then set up to display numerically the true position of the tool tip at all times.

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 arranged to display co-ordinates of the position of a holder of the operating element, the operating element position and its offset relative to the holder, and arranged to write in data as to the offset by actuating the manual drives when these are disabled from driving the holder and the operating element is in a co-operating position with a known-dimension workpiece.

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 schematic diagram of a workpiece and machining tool and its holder in a lathe.

The diagram shows a tool holder 10 in which is held a machining tool 12. Manual hand wheels are provided for effecting movement of the tool holder and its tool along the X and Z axes relative to a workpiece 14. For the X axis, the numerical control system includes a numerical display which (at selecting by an appropriate push-button) will show the X co-ordinate of the tool holder, or of the tool tip, or the tool length. A similar numerical display is provided for the Z axis.

For example in the case of the tool length offset, suppose a finished workpiece of known diameter is in place. The the tool holder is driven by the manual hand wheels until the tool tie physically touches the outer surface of the workpiece. Then an appropriate push-button is actuated to select a "tool length adjustment" mode in which the handwheels are enabled to put data into the system without actually moving the tool holder and its tool. The the "tool position" display is selected, and the X-axis handwheel is manually turned until the display shows a value equal to the known diameter of the workpiece.

The correct data for tool offset is then written into the system memory from this.

Alternatively, an approximate measurement may be made of the tool length (using a ruler for example). Then the "tool length" display is selected and the "tool length adjustment" mode is selected and the X-axis handwheel turned until the displayed value approximates to the measured tool length. Then the system is returned to the normal mode and an actual cut is taken on a workpiece. The diameter of the workpiece at this cut is then measured with a micrometer, and the procedure outlined in the previous paragraph is carried out using this cut workpiece as the reference.

Similar procedures are carried out for the Z axis offset.

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 arranged to display co-ordinates of the position of the operating element, and arranged to write in data as to an offset of the operating element from its holder by actuating the manual drive for the corresponding axis, when this drive is disabled from driving the holder and the operating element is in a co-operating position with a knowndimension workpiece, the manual drive driving the display until a value is displayed corresponding to said known dimension.

2. A numerical control system as claimed in claim 1, in or for a lathe and in which said operating element is a machining tool and said offset is the offset of the tip of the machining tool from a datum on the tool holder.

3. 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 substantially as herein described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Control of production equipment This invention relates to production equipment having an operating element, for example a lathe having a machining tool, which in use executes controlled movements relative to a workpiece. 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 example of a lathe, the machining tool is removably held in a tool holder. The numerical control system is generally arranged to give numerical displays of the co-ordinates of the tool holder position, but this numerical data requires modification (according to the offset of the tool tip from the tool holder position) if it is to give directly the actual tool tip position. Hitherto, this has been carried out by physically measuring the offset of the tool tip from the datum on the tool holder (e.g. measuring tool length), then keying this into the control system for the system to subtract this measurement from the displayed data and modify the latter accordingly, so that the control system is then set up to display numerically the true position of the tool tip at all times. 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 arranged to display co-ordinates of the position of a holder of the operating element, the operating element position and its offset relative to the holder, and arranged to write in data as to the offset by actuating the manual drives when these are disabled from driving the holder and the operating element is in a co-operating position with a known-dimension workpiece. 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 schematic diagram of a workpiece and machining tool and its holder in a lathe. The diagram shows a tool holder 10 in which is held a machining tool 12. Manual hand wheels are provided for effecting movement of the tool holder and its tool along the X and Z axes relative to a workpiece 14. For the X axis, the numerical control system includes a numerical display which (at selecting by an appropriate push-button) will show the X co-ordinate of the tool holder, or of the tool tip, or the tool length. A similar numerical display is provided for the Z axis. For example in the case of the tool length offset, suppose a finished workpiece of known diameter is in place. The the tool holder is driven by the manual hand wheels until the tool tie physically touches the outer surface of the workpiece. Then an appropriate push-button is actuated to select a "tool length adjustment" mode in which the handwheels are enabled to put data into the system without actually moving the tool holder and its tool. The the "tool position" display is selected, and the X-axis handwheel is manually turned until the display shows a value equal to the known diameter of the workpiece. The correct data for tool offset is then written into the system memory from this. Alternatively, an approximate measurement may be made of the tool length (using a ruler for example). Then the "tool length" display is selected and the "tool length adjustment" mode is selected and the X-axis handwheel turned until the displayed value approximates to the measured tool length. Then the system is returned to the normal mode and an actual cut is taken on a workpiece. The diameter of the workpiece at this cut is then measured with a micrometer, and the procedure outlined in the previous paragraph is carried out using this cut workpiece as the reference. Similar procedures are carried out for the Z axis offset. 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 arranged to display co-ordinates of the position of the operating element, and arranged to write in data as to an offset of the operating element from its holder by actuating the manual drive for the corresponding axis, when this drive is disabled from driving the holder and the operating element is in a co-operating position with a knowndimension workpiece, the manual drive driving the display until a value is displayed corresponding to said known dimension.

2. A numerical control system as claimed in claim 1, in or for a lathe and in which said operating element is a machining tool and said offset is the offset of the tip of the machining tool from a datum on the tool holder.

3. 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 substantially as herein described with reference to the accompanying drawing.