GB1587971A

GB1587971A - Apparatus for measuring lengths

Info

Publication number: GB1587971A
Application number: GB2784777A
Authority: GB
Original assignee: SETIM SOC
Current assignee: SETIM SOC
Priority date: 1976-11-19
Filing date: 1977-07-04
Publication date: 1981-04-15
Also published as: FR2371672B1; DE2730654A1; FR2371672A1; JPS5364545A; ES460186A1; IT1117447B

Description

(54) APPARATUS FOR MEASURING LENGTHS (71) We, SOCIETE S.E.T.I.M. of 24, Place des Vosges, 54 000 Nancy France, A french body Corporate, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to apparatus for measuring the lengths of objects, particularly of long metallurgical products.

Such an appartus previously devised by the Applicants is in the form of a light emitting-receiving assembly comprising a light conducting rod as a receiver which communicates at its ends with photosensitive elements enclosed in a mobile cylinder having one or more slots and being rotated by a stepping motor. The rotating cylinder is, in turn, enclosed in an opaque cylinder formed with a longitudinal slot extending along a generatrix for transmitting light from a luminous zone, which comprises . a luminous tube illuminating a parabolic reflector. Rotation of the cylinder results in the displacement of a light window or light section along the rectangular opening in the fixed cylinder.

This type of apparatus has the disadvantage of requiring a complex assembly of delicate elements difficult to manufacture, such as the parabolic reflector, light conducting tube, slotted cylinder and so on.

The invention provides apparatus for measuring the lengths of objects such as moving or stationary metallurgical products, which comprises in combination a centrallyilluminated orthogonal dihedron light emitting unit adapted to produce a parallel beam and a light receiving unit having a mobile support movable by a rotatable control member provided with one or more helical grooves or slots and guided by at least one guide member which allows rectilinear movement of the support yet prevents angular movement of the support, the support carrying a photo-sensitive element at the end of a light guide rod or tube which in use faces the light emitting unit.

The invention thus has various advantages: - precision, - measure stability, - mechanism simplicity, - maximum use of components avail able on the market.

The invention will now be more particularly described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an apparatus according to the invention; Figure 2 is a perspective view of an alternative form of the receiving unit of the apparatus; Figure 3 is a cross-sectional view of the light emitting unit of the apparatus; Figure 4 is a transverse cross-sectional view of the receiving unit of the apparatus, and Figure 5 is a longitudinal cross-sectional view of the receiving unit.

The apparatus for measuring lengths, according to the invention, generally comz prises a light-emitting unit 1 having centrally-illuminated orthogonal dihedrons adapted to produce a beam of parallel rays 2.

The apparatus according to the invention also comprises a light receiving unit 3 having a mobile support block 4 adapted to be laterally displaced by a control rod 5 rotated by an electric motor 6 e.g. a stepping motor. The mobile support block 4 also slides on one or more guide rods, such as that indicated by 7, thereby ensuring a stable translational movement. The mobile support block 4 carries a cell-bearing member 8 on its front face, the member 8 bearing a photo-electric cell 9 facing one end of a light-guide tube or rod 10 mounted perpendicular to the front face of the member 8.

Figures 4 and 5 show the inner structure of the mobile support block in more detail.

The body of the mdbile support block 4 has two symmetrically shaped parts 11 and 12 each of which has a respective cylindrical bore 13 and 14, for respectively locating the control rod 5 and a guide rod 7. The control rod 5 is formed with two pairs of flats 15 extending parallel to the axis of the rod and perpendicular to one another at their respective common edges.

Each of the flats has at its edge opposite to the common edge a vertical wall 16 the outline of which is helically shaped with a pitch such as to be entirely traversed upon each revolution of the motor 6. The vertical walls 16 serve as rolling paths for respective rolling elements 17 each carried by a shaft 18 made rigid with a support member 19 by means of a traverse screw 20 for the upper rolling elements and by means of an upper blocking ring 21 fixed by screws 22 for the lower rolling elements. The other bore 14 is provided with a ball bearing 22a serving to support in displaceable manner the mobile block on the guide rod 7.

As shown in Figure 5, the cell-carrying member 8 is in the form of a screw-threaded bush 23 having an upper cylindrical housing 24 containing the photoelectric cell 9 fixed in position by an intermediate member 25 formed with a central lighting conduit 26.

The intermediate member 25 has an upper extension 27 with a screw-threaded side-wall on which there is mounted the light-guide rod 10, which comprises a tubular element the bore 28 of which is located as a prolongation of the conduit 26. The light-guiding rod 10 has at its free end an opening 29 designed to receive light beams from the light emitting unit 1 along its axis.

With reference to Figure 3, the light emitting unit comprises one or more orthogonal dihedrons 30 with reflecting surfaces facing the receptor, each dihedron 30 having in its bisecting plane perpendicular to the edge of the dihedron and in the median position thereof a lighting tube 31 fixed at 32 to a support 33 and fed by electric cables 34. Each tube 31 has a straight longitudinal filament 35, and this arrangement makes it possible to obtain the beam of rays 2 parallel to one another and to the bisecting plane of the dihedron. The tube emits rays perpendicular to its body, the said rays being reflected by each of the reflecting walls 36 and 37 of the dihedron, e.g. consisting of stainless steel, at an angle of incidence of 45 .

A simplified embodiment of light receiving unit according to the invention is shown in Figure 2. In this embodiment, the mobile support block is generally shaped as a bush 38 having on one of its faces a member 39 designed to carry the photo-sensitive element 9 and light-guide rod 10. The bush 38 is slidably mounted on a smooth rod 40 by way of ball bearings.

The bush can be slid along the rod 40 by an external device e.g. an assembly com prising a rotatable inner cylinder having a helical slot (shown diagrammatically at 43), and a co-axial outer fixed cylinder having a rectilinear slot (shown diagrammatically at 42) extending along a generatrix, the intersection of these two slots 42, 43, delimiting a window 41, generally in the shape of a rhombus, which is rectilinearly displaced along the rectilinear slot during rotation of the inner cylinder and through which, as shown, the light guide rod 10 extends.

Hence, as the window 41 is rectilinearly displaced along the rectilinear slot, the bush 38 is slid along the rod 40.

It will be noted that this latter solution requires the use of an external rotating device.

These devices, particularly the apparatus of Figure 1, permit the length of objects to be measured, for example the length of metallurgical products. An object, to be measured, lies between the light emitting unit 1 and the light receiving unit 3, which is arranged with the light guide rod facing the unit 1, and extends longitudinally in a direction parallel to the direction of movement of the bush 38. The length of the object can be measured by detecting the illumination variation of the cell when passing from a shade zone, in which light from the unit 1 to the unit 3 is interrupted by the object, to a light zone beyond the end of the object, by displacement of the product itself and/or of the mobile support of the light receiving unit 3.

It is thus possible to effect measurement of a stationary object in abutment with a stop, when the end of the light-guide rod 10 upon passing the end of the product remote from the stop causes the cell 9 to be illuminated. This generates a detection signal to stop the motor 6 and the counting.

It is also possible to effect measurements while the objects are moving. The electronic processing is then such as to make it possible to control the motor 6 so that the end of the light-guide rod 10 constantly follows the front of the product until the end of the travel of the light receiving unit 3, the measurement terminating when the rear end of the object has exceeded the useful length of the control rod 5.

The invention is not limited by the above particular description and various modifications in configuration, materials, and in combinations are possible within the scope of the appended claims.

WHAT WE CLAIM IS:- 1. Apparatus for measuring the lengths of objects such as moving or stationary metallurgical products, which comprises in combination a centrally-illuminated orthogonal dihedron light emitting unit adapted to produce a parallel beam and a light receiving unit having a mobile support mov

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. locating the control rod 5 and a guide rod 7. The control rod 5 is formed with two pairs of flats 15 extending parallel to the axis of the rod and perpendicular to one another at their respective common edges. Each of the flats has at its edge opposite to the common edge a vertical wall 16 the outline of which is helically shaped with a pitch such as to be entirely traversed upon each revolution of the motor 6. The vertical walls 16 serve as rolling paths for respective rolling elements 17 each carried by a shaft 18 made rigid with a support member 19 by means of a traverse screw 20 for the upper rolling elements and by means of an upper blocking ring 21 fixed by screws 22 for the lower rolling elements. The other bore 14 is provided with a ball bearing 22a serving to support in displaceable manner the mobile block on the guide rod 7. As shown in Figure 5, the cell-carrying member 8 is in the form of a screw-threaded bush 23 having an upper cylindrical housing 24 containing the photoelectric cell 9 fixed in position by an intermediate member 25 formed with a central lighting conduit 26. The intermediate member 25 has an upper extension 27 with a screw-threaded side-wall on which there is mounted the light-guide rod 10, which comprises a tubular element the bore 28 of which is located as a prolongation of the conduit 26. The light-guiding rod 10 has at its free end an opening 29 designed to receive light beams from the light emitting unit 1 along its axis. With reference to Figure 3, the light emitting unit comprises one or more orthogonal dihedrons 30 with reflecting surfaces facing the receptor, each dihedron 30 having in its bisecting plane perpendicular to the edge of the dihedron and in the median position thereof a lighting tube 31 fixed at 32 to a support 33 and fed by electric cables 34. Each tube 31 has a straight longitudinal filament 35, and this arrangement makes it possible to obtain the beam of rays 2 parallel to one another and to the bisecting plane of the dihedron. The tube emits rays perpendicular to its body, the said rays being reflected by each of the reflecting walls 36 and 37 of the dihedron, e.g. consisting of stainless steel, at an angle of incidence of 45 . A simplified embodiment of light receiving unit according to the invention is shown in Figure 2. In this embodiment, the mobile support block is generally shaped as a bush 38 having on one of its faces a member 39 designed to carry the photo-sensitive element 9 and light-guide rod 10. The bush 38 is slidably mounted on a smooth rod 40 by way of ball bearings. The bush can be slid along the rod 40 by an external device e.g. an assembly com prising a rotatable inner cylinder having a helical slot (shown diagrammatically at 43), and a co-axial outer fixed cylinder having a rectilinear slot (shown diagrammatically at 42) extending along a generatrix, the intersection of these two slots 42, 43, delimiting a window 41, generally in the shape of a rhombus, which is rectilinearly displaced along the rectilinear slot during rotation of the inner cylinder and through which, as shown, the light guide rod 10 extends. Hence, as the window 41 is rectilinearly displaced along the rectilinear slot, the bush 38 is slid along the rod 40. It will be noted that this latter solution requires the use of an external rotating device. These devices, particularly the apparatus of Figure 1, permit the length of objects to be measured, for example the length of metallurgical products. An object, to be measured, lies between the light emitting unit 1 and the light receiving unit 3, which is arranged with the light guide rod facing the unit 1, and extends longitudinally in a direction parallel to the direction of movement of the bush 38. The length of the object can be measured by detecting the illumination variation of the cell when passing from a shade zone, in which light from the unit 1 to the unit 3 is interrupted by the object, to a light zone beyond the end of the object, by displacement of the product itself and/or of the mobile support of the light receiving unit 3. It is thus possible to effect measurement of a stationary object in abutment with a stop, when the end of the light-guide rod 10 upon passing the end of the product remote from the stop causes the cell 9 to be illuminated. This generates a detection signal to stop the motor 6 and the counting. It is also possible to effect measurements while the objects are moving. The electronic processing is then such as to make it possible to control the motor 6 so that the end of the light-guide rod 10 constantly follows the front of the product until the end of the travel of the light receiving unit 3, the measurement terminating when the rear end of the object has exceeded the useful length of the control rod 5. The invention is not limited by the above particular description and various modifications in configuration, materials, and in combinations are possible within the scope of the appended claims. WHAT WE CLAIM IS:-

1. Apparatus for measuring the lengths of objects such as moving or stationary metallurgical products, which comprises in combination a centrally-illuminated orthogonal dihedron light emitting unit adapted to produce a parallel beam and a light receiving unit having a mobile support mov

able by a rotatable control member provided with one or more helical grooves or slots and guided by at least one guide member which allows rectilinear movement of the support yet prevents angular movement of the support, the support carrying a photosensitive element at the end of a light guide rod or tube which in use faces the light emitting unit.

2. Apparatus as claimed in claim 1, wherein the control member is a rod formed with two pairs of flats parallel to its axis and perpendicular to one another at their respective common edges, each flat being provided at its edge opposite to the common edge with a vertical wall having a helical path with a predetermined pitch which is entirely covered on each revolution of the control rod.

3. Apparatus as claimed in claim 1, wherein the light emitting unit comprises one or more orthogonal dihedrons having reflecting side walls facing the receiving unit, each wall having in its bisecting plane perpendicularly to the corner of the dihedron and in a median position a lighting tube.

4. Apparatus for measuring lengths, substantially as herein described and shown in Figures 1, 3, 4 and 5 or Figures 1 and 3 as modified by Figure 2 of the accompanying drawings.