WO2005088414A2

WO2005088414A2 - Method and arrangement for working profile blanks

Info

Publication number: WO2005088414A2
Application number: PCT/FI2005/050064
Authority: WO
Inventors: Jukka Gustafsson; Mikko Veikkolainen; Juhani Säikkö
Original assignee: Aker Finnyards Oy
Priority date: 2004-03-12
Filing date: 2005-03-04
Publication date: 2005-09-22
Also published as: FI20045073A; FI117086B; FI20045073A0; CN100465836C; WO2005088414A3; CN1930538A; KR20060125906A; EP1723478A2

Abstract

A method and an arrangement for finishing a number of different pre-treated profile blanks, such as T-bars or the like, at a finishing station provided with a transport means for transporting the profile blanks, positioning means for profile blanks, imaging means, at least one finishing robot and a computer-based control system. The method includes the following operations accomplished at the finishing station: each profile blank is introduced into the finishing station by means of the transport means and positioned into a certain preknown position; a selected field of view of the profile blank is photographed by means of the imaging means; the basic form and essential dimensions of the profile blank are detected from the picture; certain forms, taught to the control system and deviating from a regular profile blank, especially lead-through openings, lightening holes and yield cuts, are searched and identified from the picture, on the basis of which a classification of the profile blank is achieved, the control system determining the further operations to be carried out in each case on the basis of the classification; the control system controls the finishing robot to accomplish one or more of the following operations: milling, grinding and/or cutting the profile blank, or the profile blank is moved directly to the next step; the profile blank is moved one field of view forward in the finishing station.

Description

Description METHOD AND ARRANGEMENT FOR WORKING PROFILE BLANKS

[1] The present invention relates to a method according to the preamble of claim 1 and an arrangement according to the preamble of claim 11 for finishing a number of different pre-treated profile blanks, such as T-bars or the like at a finishing station provided with transport means for transporting profile blanks, positioning means for the profile blanks, imaging means, at least one finishing robot and a computer-based control system.

[2] Welded T-profile bars or the like are used especially in the hull structures of ships, the bars being different in size and being provided during pre-treatment with various lead-throughs for pipings and cables, lightening holes or yield cuts for installing stiffening bars to be installed across each other. The T-profile bars to be finished form a part of the steel or aluminium structure of the deck of a ship or other marine vehicle or marine-technical apparatus or a bridge. During the finishing of such bars, for example, the sharp edges of holes are milled and ground and the ends are cut to predetermined length, which in the manufacturing of a ship is the most time-consuming, monotonous, heavy and unergonomic work phase. The problem is great especially in cruise ships, because the amount of bars is very large, 10000 - 15000 individual parts depending on the size of the ships, which corresponds to 40 - 60 km of bars per ship. The are no known alternatives to the above-described procedure based on manual work.

[3] Traditionally, in individual production working of the pieces as described above is largely carried out manually, because a large part of the structures are technically or economically unsuitable for working with current automated working machinery. In, for example, shipbuilding a robotised working of T-profile bars has not been possible so far in practical production due to, e.g. problematic programming and the inadequate precision of manufacture of the bar blank. The precision of the profile itself and its positioning precision have not in practice been adequate due to welding transformations occurring in an earlier phase for basing robotisation on information from, for example, the planning system. The bars to be finished are unique pieces and thus, in practice, it has been impossible to automate their working and manufacture by traditional means, such as using a macro-based or graphic remote programming. These problems have not been solved in any known dockyard building passenger ships.

[4] The present invention aims to eliminate the setbacks of the known handcraft- intensive methods especially producing various profile blanks in shipbuilding and more specially their finishing and to produce a new type of solution, by means of which the amount of manual labour can be minimised and thereby to essentially increase both the production volume and the quality of work. More specifically the invention aims to produce a method of working especially T-profile blanks, but also profile blanks of other cross-section in their finishing stage, wherein the profile blanks can be actively acted on during the whole working process. The aim is that a detection of the special features of the different profile blanks introduced one after the other to the finishing station and defining of the operations necessary in each case on the basis of the detection can be arranged as automatically as possible.

[5] The aims of the invention can be achieved as disclosed in claim 1 and described in more detail in the other claims. The method according to the invention comprises the following operations executed at the finishing station:

[6] - each profile blank is introduced to the finishing station by means of transport means and positioned to a certain preknown position,

[7] - a selected field of view of the profile blank is photographed with the imaging means,

[8] - the basic form and the essential dimensions of the profile blank are detected from the picture,

[9] - certain forms, taught to the control system and deviating from a regular profile blank, especially lead-through openings, lightening holes and yield cuts are searched and identified from the image, on the basis of which a classification of the profile blank is accomplished, on the basis of which the control system determines the further operations to be carried out in each case,

[10] - the control system controls the finishing robot to accomplish one or more of the following operations: milling, grinding and/or cutting the profile blank, or the profile blank is moved directly to the next step,

[11] - the profile blank is moved one field of view forward in the finishing station.

[12] According to the invention, the source information of the programming is the piece positioned in the finishing station, i.e. a pre-worked profile blank and its imaging and measurement for detection and classification, whereby, among others, the deviation of part manufacturing accuracy from the theoretical is not detrimental. By means of the method according to the invention the amount of manual labour can be reduced to a fraction of that of known methods and simultaneously the quality and safety levels of the production can essentially be increased and pass-through times improved. With the invention, automating the heavy, dusty and unpleasant grinding and cutting work is possible by using robotics based on machine vision programming and control. The invention can in addition to T-bars be applied to other types of profile blanks, such as H-, L- and I-bars and the material of the piece to be worked can be steel or other cor- responding material, especially used in shipbuilding.

[13] The position of the profile blank when positioning it on the station can vary depending on the shape of the profile blank, but in the case of, for example, a T-bar the profile blank is preferably upright with the stiffening part upwards. The field of view is illuminated for imaging so that the lighting conditions are as constant as possible so that the holes, dimensions and location of the profile blank are suitably visible.

[14] The height, width and thickness, among others, of various portions of the profile blank can be considered its essential dimensions. In the method, one or more cameras can be used for photographing depending on the total arrangement and they are arranged in the surrounding structure. This also applies to the amount of finishing robots, whereby different working operations can be carried out as necessary by means of various robots.

[15] Further, the concept finishing station must be understood broadly, it can comprise a whole finishing track, along which both the profile blank or profile blanks to be worked continuously advance so that their precise location is continuously known. Thus, both the camera and robot means can be synchronised to correspondingly move along the track. Thus, it is possible to even have a number of objects to be worked on simultaneously on the track and more than one profile blank to be worked in different steps.

[16] The use of the method can be made more effective by defining the objects to be measured related to the said taught forms in more detail on the basis of the classification of the profile blanks, whereby the data from the detailed measurements are compared with the conditions related to the taught forms. Then, when setting the suitable conditions, deviations, which could damage the tools during working or which are caused by the insufficient accuracy of the work steps prior to finishing or which are based on totally new ideas related to form, for example, can be taken into consideration. These deviations can preferably be used for further development of the control system and improving the total quality control.

[17] In case the defined conditions are met, the control system creates the data and transmits them to the individual positioning points of the operation places and/or the carrying out of the whole operation schedule for controlling the finishing robot for executing the programs accomplishing the various finishing operations.

[18] If there are no identifiable taught forms or if the measurement data deviate in a predetermined manner from the comparison data input into the control system, the control system guides the profile blank to move into the next step without any actions by the finishing robot.

[19] The measurement operations depend on the form to be measured so that in case the taught opening is a round opening, its diameter is measured. When the taught form is oval or the like, its curve radii and/or the location of the origos of the corner points are measured. Here, the word "oval" is to be broadly understood especially as various forms used in shipbuilding, including, e.g. rectangles with corners rounded in various ways.

[20] Further, if the taught form is a rectangular opening, its length and breadth are measured, and if the taught opening is a so-called bulb opening, the location of its corner points are measured.

[21] In order to control the finishing operations the exact positioning information of the profile blank is defined by means of, e.g. a laser rangefinder permanently fixed in connection with the finishing robot. Thus the precision of the positioning of the profile blank and the exact control of metalworking operations can be assured even in the case that previous manufacturing operations, such as welding the web of a T-bar have caused detrimental form deviations.

[22] The invention also relates to an arrangement for finishing a number of different pre- treated profile blanks, such as T-bars or the like, at a finishing station provided with conveyor means for transporting profile blanks, means for positioning the profile blanks, imaging means, at least one finishing robot and a computer-based control system. In an arrangement according to the invention each profile blank is arranged to be introduced into the finishing station by means of the conveyor means and to be positioned at a preknown position. A selected field of view is arranged to be photographed by means of the imaging system and the basic form and essential measurements of the profile blank are arranged to be detected from the picture as well certain forms, deviating from a regular profile blank, especially lead-through openings, lightening holes and yield cuts, taught to the control system are arranged to be searched and identified, on the basis of which a classification of the profile blank is arranged to be accomplished, the control system being arranged to define further operations to be performed in each case on the basis of the classification. The control system is arranged to control the finishing robot to accomplish one or more of the following operations: milling, grinding and/or cutting a profile blank or the profile blank is arranged to be moved directly to the next step. Subsequent to this the profile blank is arranged to be moved one field of view forward in the finishing station.

[23] In the following, the invention is described in an exemplary way, with reference to the appended drawings, in which

[24] D figure 1 illustrates an operation diagram of the various steps of the method according to the invention,

[25] D figure 2 illustrates some basic forms of the openings to be taught to the control system beforehand and measurement points relating to them, and

[26] D figure 3 schematically illustrates an arrangement according to the invention for finishing the profile blanks.

[27] With reference to the figures, the method is applied in the following way. Subsequent to the profile blank 2 being provided with various lead- through openings, lightening holes and/or yield cuts, it is transferred in step A to the finishing station 1 by means of transport means 3 and positioned in longitudinal and transverse direction in a way known as such. The transverse positioning can preferably be accomplished by means of press roll pairs (not shown).

[28] Subsequent to this, the work area is photographed on its selected field of view 7 in step B by means of a camera 6 belonging to the imaging system, the camera being supported, if necessary, by the structures (not shown in detail) at a suitable distance from the profile blank, so that no detrimental picture distortions are formed. By using the camera image in step C classification of the profile blank is accomplished, whereby the position of the end of the profile blank 2, various holes 2a at the web of the profile blank, such as the said yield cut, lightening hole, lead-through as well as the cutting of the profile blank, the position of the profile blank and/or the markings of the identification data and cutting marks are detected at the finishing station 1. These observations can be transmitted from the camera 6 directly to the control of the finishing robot 4 supported by the support frame 5 or the camera image can be analysed by means of the control system that transmits the data to the control of the finishing robot 4. It is to be noted that the control system is to be understood broadly so that it can comprise a rather centralised data input, analysis and control, but it can as well be accomplished in a rather decentralized way as a part of the actual imaging system and/or especially the control of the finishing robot, based on the capabilities of the processor and control means related to the selected means.

[29] Subsequent to this the finishing robot 4 could, as consequence of step F, in principle start the milling operations by carrying out, for example, the cutting of the end of the profile, then the form holes cut or milled in the points marked in the profile and, finally, grinding of the ends and the holes.

[30] The use of the method can, however, be made more effective by defining the objects, related to the forms taught beforehand to the control system, to be measured and accomplishing their measuring in closer detail in step D on the basis of the classification of the profile blank 2 carried out in step C, whereby the information received from the detailed measurements is compared to the set conditions related to the forms taught in step E. Using suitable conditions makes it possible to attempt to beforehand eliminate working operations that could damage the tools during working. Deviations can also be an indication of excessive form deviations caused by previous working steps or they can be due to totally new applications relating to form. Such deviations can preferably be used for further developing the control system and the quality of the whole manufacturing process.

[31] In case the pre-set conditions are met, the control system accomplishes and transmits in step F data about each positioning point of the operation points and/or carrying out the whole operation program for executing the programs carrying out the various finishing operations for the control of the finishing robot 4. If, on the other hand, taught identifiable forms are not found, or if the measurement data deviate from the comparison data fed into the control system in a predetermined way, the control system guides the profile blank to move to the next step without any operations by the finishing robot 4.

[32] When all operations relating to the work area defined by the field of view 7 are accomplished, the profile blank is moved one field of view forward in the finishing station 1, until the whole profile blank is photographed and worked on. Additionally, the profile blank has been provided with markings even before the finishing station for cutting it into the desired dimensions. Subsequent to this, the profile blank is transferred by means of transport means 3 away from the finishing station to an intermediate storage or the like.

[33] Figure 2 shows some basic forms occurring in the profile blanks and taught to the control system beforehand as well as their measurement points, which are marked with a circled cross. Figure 2a shows a so-called bulb opening, from which the location of comer points is measured. The diameter is measured from a circular opening according to figure 2b. The dimensions, i.e. length and width are measured from a rectangular opening shown in figure 2c. Figure 2d shows an oval or the like opening, from which curve radii and/or positions of the origos of the corner points are measured. Oval is to be understood broadly, especially in forms used in the stiffeners used in shipbuilding, including for example rectangles with corners rounded in various ways shown in figure 2d. For example, the minimum/maximum for radiuscurvature, the smallest diameter to be worked can be input as comparison data for the measurement points.

[34] In figure 3, reference number 8 refers to a tool stock, from which the finishing robot 4 picks up various tools for carrying out various finishing operations.

[35] In order to control the finishing operations the precise position data can be defined, for example, by means of a laser rangefinder (not shown) supported to the support frame 5 of the finishing robot 4 depending on the distance of the precise measurement range of the sensors of the laser rangefinders. Thus a precise positioning of the profile blank and exact control of the working operations can be ensured also in the case that previous work steps, such as welding the web of a T-bar, has caused detrimental form deviations to the profile blank.

[36] Thus, the arrangement according to the invention photographs the profile blank entering the work area, detects its openings and outlines, analyses and compares the picture data to the criteria provided previously, forming the necessary operation programs automatically and continuously on the basis of rules defined from the locations of the work points. CAD or other geometric data is not needed as input data, and the operations carried out on the basis of detections can be totally prearranged or they might need some clarifying data. In case the data are needed, they can be input either via the operating system or they can be read from an accompanying memory following the profile with, for example, a bar code.

[37] The most simple and least expensive embodiment is detection with one camera together with a laser rangefinder, the rangefinder determining the exact location of the profile blank to the control system. Laser measurement is needed as long as considerable form deviations can be caused by the welding work of previous work steps. In this case the field of view corresponding to the work area is about 1 metre in the longitudinal direction. Using a number of cameras and finishing robots the finishing of the profile blanks can naturally be made more effective, similar to arranging the said means to move simultaneously with the profile blank. The price of such systems is correspondingly of a different order of magnitude.

[38] The invention is not related to the embodiment described above, but a number of modifications of the invention are possible on the basis of the appended claims.

Claims

[1] 1. A method for finishing a number of different pre-treated profile blanks, such as T-bars or the like, at a finishing station provided with a transport means for transporting the profile blanks, positioning means for profile blanks, imaging means, at least one finishing robot and a computer-based control system, characterized in that the method includes the following operations accom-plished at the finishing station: D each profile blank is introduced into the finishing station by means of the transport means and positioned into a certain preknown position, D a selected field of view of the profile blank is photographed by means of the imaging means, D the basic form and essential dimensions of the profile blank are detected from the picture, D certain forms, taught to the control system and deviating from a regular profile blank, especially lead-through openings, lightening holes and yield cuts, are searched and identified from the picture, on the basis of which a classification of the profile blank is achieved, the control system determin-ing the further ope rations to be carried out in each case on the basis of the classification, D the control system controls the finishing robot to accomplish one or more of the following operations: milling, grinding and/or cutting the profile blank, or the profile blank is moved directly to the next step, D the profile blank is moved one field of view forward in the finishing station.

[2] 2. A method according to claim 1, characterized in that the objects related to the said taught forms to be measured in more detail are determined on the basis of the classification and that the data from the detailed measurements are compared to the pre- set conditions related to the taught forms.

[3] 3. A method according to claim 2, characterized in that the control system creates and transmits the data to the each positioning point of the operation objects and/ or to the execution of the whole operation program for controlling the finishing robot for carrying out the programs accomplishing the various finishing operations in case the set conditions are met.

[4] 4. A method according to claim 2, characterized in that the control system guides the profile blank to move into the next step without any operations of the finishing robot in case no identifiable taught forms are found.

[5] 5. A method according to claim 2, characterized in that the control system guides the profile blank to move to the next step without any operations by the finishing robot in case the measurement data deviate from the comparison data input into the control system in a predefined way.

[6] 6. A method according to any of claims 2-5, characterized in that in case the taught form is a circular opening, its diameter is measured.

[7] 7. A method according to any of claims 2-6, characterized in that in case the taught form is oval or the like, its curvature radii and/or the locations of origos are measured.

[8] 8. A method according to any of claims 2-7, characterized in that in case the taught form is a rectangular opening, its length and breadth are measured.

[9] 9. A method according to any of claims 2-8, characterized in that in case the taught form is a so-called bulb opening, the location of its corner points is measured.

[10] 10. A method according to any of the preceding claims, characterized in that in order to control the finishing operations the precise positioning information of the profile blank is determined, for example, by means of a laser range-finder supported in connection with the finishing robot.

[11] 11. An arrangement for finishing a number of different pre-treated profile blanks (2), such as T-bars or the like, in a finishing station (1) provided with a transport means (3) for transporting the profile blanks, positioning means for profile blanks, imaging means (6), at least one finishing robot (4) and a computer-based control system, characterized in that each profile blank (2) is arranged to be introduced to the finishing station (1) by means of the transport means (3) and positioned in a certain preknown position, that a selected field of view (7) of the profile blank (2) is arranged to be photographed by means of the imaging system, the basic form and essential dimensions are arranged to be detected from the picture and certain forms (2a), especially lead- through openings, lightening holes and yield cuts, deviating from the regular profile blank (2), taught to the control system, are arranged to be searched and identified, on the basis of which a classification of the profile blank (2) is arranged, the control system being arranged to determine further operations to be performed in each case on the basis of the classification, that the control system is arranged to control the finishing robot (4) to accomplish one or more of the following operations: milling, grinding and/ or cutting the profile blank (2), or the profile blank (2) is arranged to be moved directly to the following step, and that the profile blank (2) is arranged to be moved one field of view (7) forward in the finishing station (1).

[12] 12. An arrangement according to claim 11, characterized in that the objects related to the said taught forms (2a) on the basis of the classification of the profile blank (2) to be measured in more detail are arranged to be defined and that the data from the detailed measurements are arranged to be compared to the set conditions related to the taught forms (2a).

[13] 13. An arrangement according to claim 12, characterized in that the control system is arranged to create and transmit data to each positioning point of the operation objects and/or to the execution of the whole procedure program for controlling the finishing robot (4) for carrying out the programs accomplishing the various finishing operations in case the set conditions are met.

[14] 14. An arrangement according to claim 12, characterized in that the control system is arranged to control the profile blank (2) to move to the next step without any operations by the finishing robot (4), in case no identifiable taught forms (2a) are found or in case the measurement data deviate from the comparison data input into the control system in a predefined way.