A METHOD FOR STEERING A MOVABLE MEMBER The invention relates to a method by means of which a movable member, as the movable head of a painting or a cutting apparatus, is controlled by means of a steering and regulation centre in the equipment unit, when cutting for instance pieces off a moving web or drawing for instance markings in a moving web with a pen steered by this method. In the method for the movable member a crosswise motion is arranged in regard to the forward direction of working, by adjustment of which motion the forward speed of the working direction is observed.

Previously known, e. g. from patent publications US 4,931, 140 and US 5,762, 759, as cutting methods of a movable web are edge cutting by means of a water jet and diagonal cutting of a movable paper web by means of a water jet nozzle. In these ones the paper web moves at constant speed and the water jet nozzles are placed in a beam mounted crosswise in regard to the web motion, in which beam the water jet nozzles are moved in crosswise direction of the web.

Water cutting devices of this kind are not fit for a case, where pieces of chosen shape should be cut off a web moving at constant speed. Crosswise cutting of web does not work, since it re quires an enormously fast crosswise motion from the apparatus. Cutting of works only from an approaching web, not more from the web portion that has passed the crossbeam conveying the cutting apparatus..

By means of the method as per the invention removal of a piece from a moving web is solved, when the removal is carried out by means of a cutting apparatus conveying in the web crosswise direction. By means of the invention also other in a moving web necessary machinings, markings can be solved, for instance studying a web in moving a detector or a measuring device on the web in a way as per the invention. The arrangement can also be carried out so that the object is immobile, for instance painting a road to be marked and moving the whole painting apparatus in the road direction.

The method as per the invention is characterized in that in order to reduce the speed of motion of the movable member in crosswise direction, the movable member is in the method moved by means of a second motion arrangement in the forward direction of working, when the movable member is cutting/working on one part of the piece and moved against the forward direction of working, when the movable member is cutting/working on another part of the piece.

The advantage of the method as per the invention is that for instance in a web cutting case, pieces of different shapes can be cut off the moving web by steering the cutting head. It is possible to cut off the web completely in the crosswise direction and it is also possible in all other cutting directions. By means of the method as per the invention the speed of motion of the steering head can be levelled in regard to the web so that the relative speed between them does not increase very much and is not impossible to carry out. By means of motion actuators, known per se, producing accurate and fast motion and with their steering units, the method as per the invention can be reliably used for conveyance of the water jet nozzle, while cutting pieces off a moving web. A further advantage of the method is that it can be used for many kinds of work.

In the following the invention is disclosed with reference to the enclosed drawing, where the use of the method for steering the water jet nozzle and the painting nozzle is illustrated.

Fig. 1 shows the head of a water jet cutting apparatus from above.

Fig. 2 shows the cutting line of an water jet nozzle after cutting.

Fig. 3 shows painting of road markings with the movable apparatus as, per the invention.

In figure 1 movable web 1, as a paper web, moves at constant speed Vx mthe ;, arrow direction, i. e. direction x. By means of an apparatus comprising water jet nozzles 9 round pieces 2 are cut off web 1. Water jet nozzle 9 is conveyed controllably in direction y, i. e. in the web crosswise direction by means of ball screw arrangement 1 la, 8a, 7. Water jet nozzle 9a is fixed in the lower surface of ball screw frame 7 by means of part 8a. Part 8a moves under rod 7, when the ball screw inside rod 7 is rotated by means of motor 1 la. Part 8a in direction y is dependent only of the nor} la rotation, which rotation is adjusted in both directions by means of cutting-cß ng steering unit. If water jet nozzle 9a cuts round shaped marks, as in figure 1, nozzle in direction y a speed of motion calculated from radius r equation proportioned to the forward speed of the web. Then the traverse ball screw frame 7 can be in place, while nozzle 9a is cutting circular marks shown in figure 1.

When a piece must be cut off the web, as intended in one embodiment of the method according to the invention, in most cases there must be a second nozzle or even several nozzles 9b to cut off one side of piece 2. In this case for nozzles 9a and 9b a phase shift is arranged in order to avoid their collision with each other. Nozzle 9b cuts symmetrically the other side of piece 2 as much as the phase shift, for instance ab. 10 cm, ahead of nozzle 9a in direction x. Both ball screws can move the nozzle end in direction y at least as much as the diameter of piece 2.

Figure 2 shows the cut mark of nozzle 9b, when nozzle 9b is making continuous motion changing side of piece 2 always at change of piece. Correspondingly, with nozzle 9a mirror image mark is cut. With this solution the nozzle 9 motions will turn out relatively even. On the other hand, there will be an unreasonably high instantaneous speed close to the spot, where y gets the value 0. The nozzle should be given a very high instantaneous crosswise speed in regard to the web, if exact circularity is demanded from piece 2. The web speed can be for instance from 30 to 60 metres each minute.

Steerings for nozzles 9a and 9b can also be made so that both nozzles are on their sides cutting only a semicircular mark. Then they are moved back and forth only a distance r, one on area + y and the other on area-y. By value y = 0 there will be for both nozzles a most abrupt alteration of course difficult to carry out, due to which the solution is not very practical. For instance, if the pieces are diamonds or similar and lack a form in web crosswise direction or close to the crosswise direction of the web, it is possible with the apparatus to cut off such pieces off a movable web.

When the piece to be cut off is a circle or some cutting line in it is in the web direction or close to it, the above method is not applicable. Therefore a method is developed, by means of which the motion of water jet nozzles 9 is levelled and the top speeds of their motions are cut off. The method as per the invention also includes an other motion arrangement, such as a ball screw arrangement 3,4, 5,10. By means of this arrangement the whole first ball screw arrangement 11,8, 6,7 can be moved controllably in web direction in both directions. By means of the second ball screw arrangement the water jet nozzles are 9a, 9b are given a speed close to the forward speed of web 1 in direction x, when nozzles 9 should cut in directions close to crosswise directions Of the web. Then the ball screws moved by motor 11 are not caused any impossible motion speeds, which the ball screws should carry out.

Correspondingly, when nozzles 9 ought to cut near the lines in web 1 direction, the first ball screw arrangement can be pulled back against the forward direction of the web without causing any unreasonable speeds to the ball screws in the first arrangement. Neither does the speed of the second ball screw arrangement get unreason able during back motion. Thanks to the back motion one can in the next phase by the means of the second ball screw arrangement move the first arrangement again in the forward direction of the web.

Figure 2 shows as an example on which area the first ball screw arrangement is moved in the forward direction of the web, and as area the cutting area E of nozzle 9b is presented. Back motion is carried out on cutting area P, when there are circular pieces to be cut off in the example. Areas E and P take turns all the time. There can be between areas E and P a cutting area, where the first ball screw arrangement is not moved in the web direct ion.

Since the pieces to be cut off can be of variable shape, the speed to be adjusted for nozzles 9a and 9b in direction y determines when motion of water jet nozzles in the web direction is needed and when back motion is possible. If the water jet nozzles must in direction y be given a speed, which is, for instance, more than 2 times the web speed Vx, then by means of the second ball screw arrangement a motion speed is given to water jet nozzles 9 also in the web direction. Possibly, this limit speed can also be another one, as for instance 3 times Vx. The steering system chooses a proper speed, which is given the water jet nozzles in the web direction. Therefore the steering system must also calculate and regulate new speed functions for water jet nozzles 9 in transverse direction so that the intended shape of piece 2 can be achieved.

The steering system regulates the second ball screw arrangement to carry out the back motion in a spot (as area P), where the speed q, f water jet nozzle 9 in direction y does not grow to the unreasonable. Also during back, haoton t steering sysl s, tp calculate and regulate new speeds for water jet nozzles 9tin in direction y.

So speed is demanded from the steering and regulation system so that it would be able to calculate rotations and directions necessary for motors 11 both in a case, where the second ball screw arrangement is in place, and when the second ball screw arrangement is moving water jet nozzles 9 both in the web direction and against it. Solution to necessary motion equations and coordinate equations can, however, be found in combining plane geometry and time function and making calculations by machine.

In the method as per the invention it is possible even by means of one water jet nozzle 9 to cut pieces off a moving web, when the first ball screw arrangement is given per each removable piece always a motion in the web direction and a back motion.

Figure 3 shows an arrangement, where the working portion, as movable members 9 and their motion arrangements are placed in a movable wagon 12, and the object, a road, is immovable, whereat it is possible to paint different road markings 13 in driving wagon 12 at smooth speed.

In markings 13, which are to be painted, there can even be shapes in crosswise direction.

As a cutting apparatus itself, there can be instead of a water jet nozzle a laser beam cutting apparatus or some other known mechanical cutting apparatus. Instead of ball screws movable members 8,9 can be moved even with other known devices making linear motion. The method is applicable to all kinds of web cutting, machining, drawing on the web, web painting and, for instance, measurement of the web qualities. Movable members can also be placed above or under the object and even several ones to be moved at the same time.