WO2001094879A1

WO2001094879A1 - A method and a device for alignment of an object in relation to a projected image

Info

Publication number: WO2001094879A1
Application number: PCT/SE2001/001276
Authority: WO
Inventors: Hans HEDSTRÖM
Original assignee: Megascale Ab
Priority date: 2000-06-09
Filing date: 2001-06-07
Publication date: 2001-12-13
Also published as: SE515503C2; AU2001274718A1; SE0002171D0; SE0002171L

Abstract

A method and a device for aligning an object relative to a projected image independently of special characteristic features of the object. Instead of using object-inherent features, there is applied to the object an indicator that consists of a rotational punctiform marking for the alignment of said object, and a scale for controlling rotation when aligning the object. The marking may be a painted, printed, scored marking to a marking applied to the object in some other way. This enables the object to be aligned precisely and selectively with the aid of a simple projected image as a reference, for instance an image comprised of mutually intersecting laser lines.

Description

A METHOD AND A DEVICE FOR ALIGNMENT OF AN OBJECT IN RELATION

TO A PROJECTED IMAGE

The present invention relates to a method and to a device for aligning an object relative to a projected image, in accordance with the preamble of the independent method Claim and in accordance with the accompanying independent apparatus Claim.

It is well known to use a projected image as a reference in order to orientate objects in assembling and manufacturing operations. Precise characteristic features of said objects, such as edges, shoulders, holes or castings/moulding marks, can be used to position said objects in relation to the projected image.

One problem with the aforesaid known technology is that it is necessary to adapt the projected image to the objects. When the projected image is comprised of intersecting lines, it may be necessary either to rotate the projected image, to alter the angle between the intersecting lines or to provide more intersection points. In the absence of precise characteristic features, it is necessary to create a light image whose contours are identical with the contours of said object. When different objects shall be assembled or fitted one after the other, or when the same type of object is assembled, mounted or fitted in different positions of alignment, it is necessary to change the light image for each object, in addition to moving said projected image. This complicates the equipment used to create or generate the light image, therewith resulting in more expensive equipment.

The aim of the present invention is to solve the aforesaid problem by providing a technique which enables different objects to be brought into alignment quickly and precisely with a readily created projected image, without needing to change said image and regardless of the shape and orientation of said objects.

This object is achieved by the invention as defined in the accompanying independent method Claim.

The object is also achieved by the device defined in the accompanying independent apparatus Claim. A fundamental feature of the invention resides in ignoring particular characteristic features of the objects. Instead, there is applied to said objects a rotational punctiform marking which identifies the rotational axes of respective objects wherewith the objects are positioned relative to the projected image in accordance with said punctiform marking, and wherewith a scale according to which the object is rotated relative to the projected image is disposed, either completely or partially, around said axis. The marking may be a painted, printed, or scored marking applied to said object, or a marking that has been applied thereto in some other way. This enables the object to be brought into precise, selective alignment with the aid of a simple projected image as a reference, for instance in the form of mutually intersecting laser lines.

The laser lines may be created, for instance, in the manner described in Swedish Patent Application 9901228-8.

The invention will now be described in more detail by way of example and with reference to the accompanying drawing.

Fig. 1 is a side view of an assembling jig for use in the manufacture of roof trusses and the like.

Fig. 2 is a plan view of a roof truss assembling jig shown prior to the process of alignment.

Fig. 3 is a plan view of a roof truss under manufacture and resting on assembling jigs.

The setting-up of assembling jigs in the manufacture of roof trusses is described as one area in which the invention can be applied. The jigs are set-up in preparation for the series production of roof trusses, normally a series of from ten to twelve trusses in number. A high degree of accuracy is required to achieve precision in sequential operations. According to conventional techniques, there is used a straight edge on the floor, the wood required for the first roof truss, and a measuring tape. The time taken to set-up a jig is about 25-30% of the total time, depending on the complexity of the roof truss. The invention enables the setting-up time to be more than halved and also enables a higher degree of precision to be attained than when setting-up a jig with the use of measuring tapes as in the case of conventional techniques.

Shown in Figs. 1 and 2 is a roof truss-assembly jig that includes a support surface 1 for the wood concerned and a groove 2 for accommodating guides 3 against which the wood shall be fitted. The jig also includes a pressure plate 4 which can be moved in a perpendicular direction and therewith raised to force corrugated fasteners, that have been placed on the plate and beneath the wood, securely into the wood. The pressure plate has engraved thereon a rotational punctiform marking 7 and a scale 8. Alternatively, the scale 8, which need not have a circular shape, may be applied on the support surface 1 closer to the outer edge of said surface, so that the scale can be made larger. A bottom plate 5 rests on a floor covered with metal sheet, and the jig is held in position by a magnet 6.

Fig. 2 shows a projected image in the form of two intersecting laser lines 9. The point of intersection of the lines indicates a position accurately calculated for the jig by the roof truss construction program, said position being given by co-ordinate points and angles on the workshop drawing. The jig 10 is placed with the rotational punctiform marking 7 in the centre of the point at which the laser lines intersect. Alignment of the object in relation to the projected image is then effected by rotation, so that the marking on the scale 8 follows one of the laser lines 9.

The procedure is then repeated in respect of remaining jigs.

The invention can also be applied to position corrugated fasteners used to fasten the roof trusses together. Fig. 3 shows roof trusses with corrugated fasteners 12 disposed in position prior to being pressed into the wood. A maximum deviation of 5 mm in positioning the corrugated fasteners is permitted with respect to calculated dimensions of wood and fasteners. The claimed method can also be applied when the corrugated fasteners are provided with markings in accordance with the invention.

Although the use of a projected image in the form of mutually intersecting laser lines has been proposed in the illustrated example, it will be understood that other forms of light images can be used when applying the invention. For instance, the projected image may have the form of a straight line that a includes a short break which denotes a centre against which said alignment takes place.

Claims

1. A method of placing an object in a chosen position on a planar working surface and in chosen orientation in the plane of said working surface, wherewith a light image is projected onto said surface, characterised by providing the object with a punctiform marking (7) and a rotatable scale (8) around said marking; including in the light image a punctiform marking and a radius reference to the punctiform marking of said light image; orientating the object relative to the projected image so that the punctiform markings of said object and said image coincide; and causing the reference radius of the image to take a chosen position of rotation along the rotational scale of said object.

2. A method according to Claim 1, characterised by forming the light image (9) from two over-crossing laser light planes which mutually intersect in the working plane; and by using the point of intersection of the laser light plane to define the punctiform marking of said image, and by using as a reference radius the projection of one of the laser light planes that forms a line (9) in the working plane.

3. A method according to Claim 1 or 2, characterised by displacing the laser light planes independently of each other so that their projections in the working plane will form lines (9) that can be displaced parallel with one another in said plane, wherewith projections of the laser light planes in the working plane each form preferably perpendicularly intersecting lines, wherewith the point of intersection of said lines constitutes said punctiform marking.

4. Plant for placing an object on a planar working surface in a chosen position and in a chosen orientation in the plane of said working surface, said plant including a device for projecting a light image onto the plane of the working surface, characterised in that the object carries a punctiform marking (7) and a rotational scale (8) around said marking; in that the light image includes a punctiform marking and a reference radius enabling the surface markings of the object and the image to be brought into alignment, wherewith the object can be given chosen orientation relative to the reference radius of the image with the aid of said scale.

5. Plant according to Claim 4, characterised in that the object is a roof truss jig; and in that the jig has adjustable guides (3) for roof truss beams.

6. Plant according to Claim 4, characterised in that the object is a corrugated fastener (12) that shall be mounted on a roof truss frame for mutual fastening of beams in said frame.