GB2052756A

GB2052756A - Improvements relating to measuring apparatus

Info

Publication number: GB2052756A
Application number: GB8015995A
Authority: GB
Original assignee: Clarks Ltd
Current assignee: Clarks Ltd
Priority date: 1979-05-14
Filing date: 1980-05-14
Publication date: 1981-01-28
Also published as: GB2052756B

Abstract

An apparatus for measuring the co-ordinates of points in space comprises a contact element 14 fixed to an arm 13 which is movable lengthwise of itself and at right angles to itself and is rotatable about an axis extending normally to the length of the arm. Movement of the contact element in each of the three senses is measured by a signal producing means which produces a signal defining the position of the contact element with respect to a datum point. The apparatus includes a recording device actuatable to record sequences of positions of the contact element defining a line or lines, a visual display unit, a computer capable of processing the signals to produce on the display unit an image of the sequences which image can be rotated to show the line or lines from different viewpoints. <IMAGE>

Description

SPECIFICATION Improvements relating to measuring apparatus This invention relates to measuring apparatus and is concerned with an apparatus for producing co-ordinates of points in space relative to a given datum. The apparatus has an important application in producing co-ordinates defining a three-dimensional line. From a plurality of such lines a three-dimensional shape can be defined and recorded, for example in an electronic storage device.

According to this invention there is provided a measuring apparatus comprising a contact element mounted for rotation about an axis spaced from the element, for rectilinear movement radially of said axis, and for movement parallel to said axis, and means for producing a signal indicative of the position of the contact element relative to a datum point when the element is in contact with a surface at a selected location on the surface.

Preferably said signal producing means is adapted and arranged so that the signal is indicative of the cartesian co-ordinates of the position of the element relative to three predetermined mutually perpendicular axes extending through said datum point.

The signal producing means conveniently also comprises means for recording the signals produced, and electrical switch means for actuating recording of and the signal produced when the element is in a selected position.

In a preferred arrangement, the sensor is mounted on one end of an arm which extends radially of the said axis of rotation and which is mounted for radial and axial sliding movement on a frame which is mounted for rotation about said axis.

One embodiment of the invention will now be described by way of example with reference to the accompanying diagrammatic drawings in which: Figure 1 is a side view of a measuring apparatus according to the invention; Figure 2 is a front view of the apparatus of Figure 1; Figure 3 is a perspective view of part of the apparatus of Figure 1; and Figure 4 is a sectional view on the line 4-4 of Figure 3.

The illustrated apparatus is intended to measure co-ordinates of selected positions on a surface relative to a given datum position, and to transfer the relevant information to a storage system, e.g. a recording tape. One particular use of this apparatus is in relation to the design of shoes, boots and similar footwear.

Referring to the drawings, two parallel side plates 10 secured to a table 11 provide journals in which a frame 12 extending between the members 10 is rotatably mounted. An arm 13 extending radially of the axis of rotation of the frame is mounted in the frame 12 in a manner not shown for sliding movement radially and axially with respect to that axis. A C-shaped stylus 14 whose tip constitutes a contact element is rotatably mounted on one end of the arm for rotation about the lengthwise axis of the arm, the tip being on said axis. This form of stylus enables the contact element to be placed against any point on a shoe last, even on the underside of the last.

The position of the arm relative to the frame can be fixed by means of clamps 1 5 which extend along opposite edges of the frame and the movable jaws 16 of which are operated by respective solenoids 1 7 under the control of the operator.

For its rotary mounting the frame is secured to a central shaft 20, and a pulley 21 is secured on one end of the shaft. A bowden cable 22 extends over the pulley 21 and round jockey pulleys 28.

The cable is clamped to the periphery of the pulley by a clamp 23. One end of the cable carries a tension weight 24 and one element 25 of a linear transducer, the other element 26 of which is secured to the frame. The other end of the cable has a counterbalance weight 27 attached to it.

It will be understood that the linear position of the transducer element 25 relative to the element 26 provides a measure of the rotational position of the frame and hence of the angular position of the arm, and the angular displacement of the arm and frame from a given datum position is measured by a counting device. In a preferred version of the apparatus the linear transducer 25, 26 is replaced by a displacement encoder in the form of an optical tape extending over the pulley and marked with graduations along its length, and a graduation counting head secured to the end plate. Similariy the radial and axial sliding movements of the arm relative to the frame are measured by digital counters, and a recording device of any convenient type is used to record coordinates of the position of the contact element when the operator actuates an operating button.

Magnetic tapes with pulse marks may alternatively be employed in conjunction with pulse counting heads.

A computer may be employed in conjunction with the apparatus to convert the polar coordinates constituted by the angular displacement of the frame and the distance of the contact element from the axis of rotation of the frame into cartesian co-ordinates based on mutually perpendicular axes which intersect and are perpendicular to the axis corresponding to that along which axial displacements of the arm are measured.

In the application of the apparatus to the design of footwear a last 30 for a shoe has adhesively attached to it, in a manner well known in the art, a piece of material known as a drape, on which a design of shoe can be drawn by the designer.

Certain lines known as style lines are also marked on the drape. The last with its drape is then fixed to the table 11 in a predetermined attitude. Either the last is mounted with a datum location of the last in a predetermined datum position or the position of the contact point of stylus 14 is zeroed on the datum location of the last. The datum location on the last is preferably the point at which a vertical on the centre line of the last and passing through the heel/ball point intersects the bottom of the last where the last is in its predetermined attitude. The last three further reference points (one at the toe and two at the heel end) of which the co-ordinates are then measured.These reference points having been thus "measured", the contact point of the stylus is then moved manually by the operator along each style line in a series of steps and at each step the operator depresses a button or other actuator which causes the co-ordinates of the contact point at that instant to be recorded. The conversion of the polar co-ordinates to cartesian co-ordinates may be carried out by a computer before recording on a medium such as tape and simultaneously displayed on a visual display unit. This unit may be provided with facilities for showing which an image of the last is shown, defined by cartesian co-ordinates. The style line is superimposed on that image. For this purpose a known device is incorporated which produces on the screen a smooth curve drawn through the co-ordinates of the style line obtained from the illustrated apparatus. The computer is designed to enable the image of the last and the style line to be rotated in unison to enable the position of the style line on the last to be shown from different viewpoints.

Claims

1. A measuring apparatus comprising a contact element mounted for rotation about an axis spaced from the element, for rectilinear movement radially of said axis, and for movement parallel to said axis, and means for producing a signal indicative of the position of the contact element relative to a datum point when the element is in contact with a surface at a selected location on the surface.

2. Measuring apparatus as claimed in claim 1, wherein the signal producing means comprises means for recording the signals produced, and electrical switch means for actuating recording of and the signal produced when the element is in a selected position.

3. Measuring apparatus as claimed in claim 1 or claim 2, wherein the contact element is mounted on one end of an arm which extends radially of the said axis of rotation and which is mounted for radial and axial sliding movement on a frame which is mounted for rotation about said axis.

4. Measuring apparatus as claimed in claim 3, wherein the contact element is formed at the tip of a generally hook-shaped extension of the arm.

5. Measuring apparatus as claimed in claim 3 or claim 4 wherein a pulley is mounted for rotation with the frame and a belt extends over the pulley and is secured to move with rotation of the pulley, one end portion of the belt constituting or having ccnnected to it one element of a device for measuring rotation of the frame as a linear displacement.

6. Measuring apparatus as claimed in claim 5, wherein said device is a linear transducer and is connected to a counting apparatus measuring said linear displacement.

7. Measuring apparatus as claimed in claim 5, wherein said device is a strip of magnetic tape movement of which past a counting head gives a measure of said linear displacment.

8. Measuring apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.