DE1913126A1 - Method and device for guiding an object at a constant distance to and along a predetermined path - Google Patents

Description

191 3126 LINDE AKTIENGESELLSCHAFT

H € 8/28 «

26. 2. 1969 Sat / kr

Method and device for guiding an object at a constant distance see below and along a predetermined path

The invention relates to a method and a device for Guiding an object, for example a processing machine or a welding torch, at a constant distance to and along a given path with a sensor * that scans the given path in a non-contacting manner and the movement of the object controls.

This occurs frequently in many areas of technology Problem on "any object", for example a processing machine or a welding torch, along a predetermined path at a constant distance from it

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^V '- * ■' ■ - ■ way to lead. The specified path can be, for example, a contour to be machined or a groove that is to be milled out. Another example of such a given path is a welding joint along which a welding torch is supposed to move. In many fills, the predetermined path is also simply the edge of a workpiece or a template or a surface from which the object is to be kept at a certain distance.

To solve this problem of guiding an object, mechanical sensors have become known which scan the given path and from which the object is controlled via some transmission mechanism. These mechanical sensors have the disadvantage that they follow the specified path, For example, touch a contour and, if necessary, control the process by touching it. * Sine such a disturbance arises, for example, when the sensor gets stuck or when frictional forces in the transmission mechanism move in the wrong direction to pretend. It is therefore known that non-contact sensors have been developed which optically follow the specified path scan and control the object via a photocell system. Such methods for guiding objects have in some cases proven their worth. However, they require a visually easy to understand path marking and also require a fairly large, equipment-like effort that cannot always be justified. The use of non-contact sensors has increased

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therefore in you technology has not yet been implemented as widely as it would be desirable.

The invention is based on the object of a method for guiding an object at a constant distance to and along a predetermined path that works reliably with a non-contact scanning probe and requires a relatively low outlay in terms of equipment.

This object is achieved in that as a sensor a plasma torch, preferably low power, connected to the object is used, the nozzle of which is influenced by it Its motor, which moves the object in a controlled manner, is kept at a constant distance from the predetermined path as a function of characteristic quantities of the plasma torch.

The method according to the invention is based on the knowledge that certain characteristic quantities in a plasma torch are very precise, for example The arc length is much more accurate than with conventional arc welding torches, proportional to the distance between the Brenners are from a Bszugselement. The main idea of the present invention therefore consists in the use of plasma torches as sensors, i.e. in the use a device commonly used as a tool for a completely different purpose.

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Plasma torches are known in welding technology. You brew « therefore do not need to be described in more detail here. Under Low-power plasma torches, which are preferred in the present context and are often also referred to as “micro-plasma torches”, are single-power burners to understand from 8 to 500 watts. Such a burner can be adjusted so that the element reproducing the predetermined path, for example a workpiece, only heats up slightly and will not be damaged.

The method according to the invention is expediently carried out in this way that the object to be guided is initially moved uncontrolled in a main direction of movement. The main direction of movement is approximately in the direction of the specified Path, for example along a straight or circular contour. The exact guidance along the specified carriage is carried out by a controlled movement of the fixed with the object connected plasma torch perpendicular to the main direction of movement. With a certain execution game of the invention @ ®iü £ $ @ n Procedure, the given path is simply the surface sines, WerketUckea, so that the object should keep a constant distance. Di · controlled movement of the object that is with is connected to the plasma torch, in this case the right on the surface of the workpiece - "* B" i "in another embodiment"! Let the given path play e.g. a "Sohwelfifuge, on its edge area or on one of its planks the arc

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the plasma torch is reddened iat. The controlled movement of the object, which is connected to the plasma torch, takes place in this case parallel to the surface of the workpieces to be welded.

Of course, the object can also be moved in a controlled manner in two mutually perpendicular directions, for example by using the two procedures described together. In this case, the object is connected to a first plasma torch and, with its help, is kept, for example, at a constant distance from a surface. A second plasma torch then controls the object together with the first torch in a direction parallel to the surface and perpendicular to the main direction of movement.

Sin Flasincbr®g% S3 @ r has several characteristic features Sizes that are suitable in the method according to the invention to guide an object as that which controls the object to serve the motor influencing variables. As examples of : Such quantities are hereinafter referred to as the arc length, the wear length of the arc and, if the main

arc of the plasma torch, in the direct current of the pilot arc treated with a free gas outlet from the burner nozzle superimposed wax flow.

In a first advantageous embodiment of the Y & rfnhr®tm , a with;

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ORIGINAL INSPECTED

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the object connected plasma torch, lower in this pall Power, used, whose arc length, which is very precisely proportional to the light arc voltage, kept constant will. For this purpose, the arc voltage is introduced into a control unit and compared there with a setpoint value. the Control unit acts on a control element in the power supply line a motor executing the controlled movement of the object is located.

For example, a device is used to carry out this process, which essentially consists of a carriage that moves uncontrolled in the main direction of movement and a carriage that slides in a carriage guide on the carriage and that carries the object with the plasma torch as a sensor. The slide is driven by a motor depending on changes in the light intensity of the plasma torch. In the case of the execution form of the process with two mutually perpendicular, controlled movements of the object, two mutually arranged carriages, each of which carries a burner, are provided in a corresponding manner. If a plasma torch is to be used for cutting or cutting ;, fcsrm. eles »Plasma torch at the same time sensor and guided objcfefe © elis»

His other Aaefuhruisgsites ^ öes erfisdwragsgeraägQsn procedure is based on the knowledge that the IbrelSllsigQ d @@. Arc, * » fXmm & MmmeTs under the-

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the other "variables which determine the properties of the arc, such as gas composition" gas flow rate, current intensity, etc., are kept constant, is very precisely constant Nozzle of the plasma torch and the workpiece and on the other hand, when the plasma torch approaches the workpiece, it is re-ignited at almost the same value of the distance, the re-ignition taking place with the help of the pilot arc that is always maintained in the plasma torch. The arc voltage of the plasma torch is used as a control variable for guiding the object; introduced into a Hegel unit on its predetermined path. When the with deer. Departing br <w "re-ignition of the arc connected discontinuous change in the arc" voltage, the control unit sends a signal to a control element "which litgt in the power supply" line of a motor executing the controlled movement of the object "this signal triggers 1" control element J "w" 11b a switching process that reverses the direction of rotation of the motor and thus the direction of movement of the object. ■. ' v / VO; "" ^ - ^. " ^: ^ - '■: ^ ■; .. ο:: ^' ■ ■ -

In this implementation of the procedure according to the invention, the controlled movement of the object is based on two opposing and laterally close

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mutually running movement elements together, the Switching to the one opposite to the previous one Direction of movement always takes place when the tear-off of the arc is exceeded in one direction or the other.

For example, in one particular embodiment of this method, the default path is simply the surface of a Workpiece to which the object should maintain a constant distance. The controlled movement of the object with the Plasma torch is connected, takes place in this case perpendicular to the surface of the workpiece. Here the object moves when the arc of the plasma torch is burning, the in this Case has low power, perpendicular to the workpiece nag and in the case of a non-burning arc perpendicular to the workpiece asu. The place of the Ob-Jektee applied over a Zeltaohse bew. The plasma torch lat therefore a zigzag line, where the length of the straight sections depends on the .Us * and it © n the workpiece depends.

However, the specified path can also be a joint «Wipe two workpieces» whereby the arc de *. ^ Plasma torch aimed at one of the two edges of the joint iet. The controlled movement of the object that is connected to the plasma torch takes place in parallel in this case Surface of the workpieces. In doing so, I move the object, des belapUlaw «! ··« in Sohwaiibrtner «, rait the two

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Workpieces are to be smoldered with burning light » arc in the direction of SfcoSfug «, upon reaching the arc leaves and thereby reverses the direction of movement of the object.

The object IKSt is also in this embodiment of the process controlled move in two mutually perpendicular directions, for example by placing the two last can be used together. In this case, the object is connected to a first plasma torch and is held with its help, for example, at a constant distance from a surface. A second Plasma torch then controls the object together with the first torch in a direction parallel to the surface and to the main direction of movement perpendicular direction.

To carry out the with the AbreiSlänge des Licht-Ii "
); bogens working method saird eg a device bej! uses »which essentially consists of a carriage» which moves uncontrolled in Ij the main direction of movement and consists of II a κ carriage sliding in a slide guide on the carriage, which moves the object together with the plasma

Brenner as Feeler is deceptive «The slide is driven by a motor

driven by Jew8ils in the manner described above i | exceeding the liability of the arc of the

Sj brensiers switched isird. When running the with two mutually perpendicular controlled movements of the

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Object are two slides arranged one on top of the other, each of which carries a plasma torch, provided * If welded or cut with a plasma torch should be, the plasma torch, as Im first ■ Example of execution described, at the same time sensor and be a managed object.

Another embodiment of the method according to the invention is based on the knowledge that in the gas outlet nozzle of a plasma torch, the main arc of which is not burning, with free, unhindered exit of the gas, a gas tube oscillation occurs which is comparable to the oscillation in a whistle. If the gas leaks in any ©? If the gas outlet nozzle of the plasma torch is brought very close to the surface of a piece or touches it, this oscillation does not occur. The characteristic in the area of the gas outlet, ie the occurrence or occurrence of the oscillation described, has, as has also been found, a very specific effect on the electric direct current flowing "through the Piletlielitbog" nd When the sc3te? Ingyag occurs, this direct current is an alternating current relatively stored, which with the disappearance "dar Oassätdeimctswingugts © i if disappears again * Srfindiaogsgerail wspdea the sife occurrence and ~ Y" rechiilnd & n <3 "er visually wobbly

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ORIGINAL INSPECTED

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UNDE AKTIENGESILSCHAFT

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the characteristics of the gas flow in the area of gas outlet nozzle used to influence a motor that moves the plasma torch and thus the object connected to it and to be guided.

When executing this method, the object is moved in a controlled manner in a main direction of movement, for example approximately parallel to the given path, uncontrolled and perpendicular to it and parallel to the area in which the main directions of movement and the given path lie. A suitable device for carrying out this method therefore consists of a chassis moving in the main direction of movement on which a slide guide is attached. In this slide guide, a slide runs perpendicular to the direction of movement of the chassis, which deceives the object to be guided as well as the plasma torch as a pusher become "full", or the hand of a sprite "is, which reproduces the path of the object. In a “very specific application”, for example, the edge _{B is} aimed at the plasma torch; one of the two edges of a welding joint and the object, a welding torch, with the help of which the sides forming the weld are to be welded to one another.

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The plasma torch is perpendicular to the course of the "edge, for example with the help of Distance rolls, so enclose * the Oaeaustrltt & nozzle so tightly as possible on the surface of the workpiece, which is through the Xante is limited «ends or just touches it lightly. As long as the gas outlet from the gas outlet nozzle through the Surface of the workpiece is obstructed * i.e. as long as none Oasis column vibrations and thus also no direct current de · pilot arc superimposed alternating current occurs «the motor moves the plasma torch towards the Xante. If the edge is over-the-ear, the oae can flow out freely, which causes it to the characteristic of the gas flow is changed in the manner described occurring alternating current 18efe in a Hegel unit a signal from there to a control element in the power supply line de · Motor · works and the direction of rotation of the motor · switches. This causes the plasma torch to move in the opposite direction towards the Xante. When the but then, if the Oae is not "more unhindered." auatrittsdUe can escape, the direction of rotation of the motor • rnaut uragesohsltet. This process repeats itself during of the "ens" n sequence of the procedure "so that the place of the Plaaeabrennaru or the" * object " a line is "where the length of the straight line depends on the course of the edge,

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The world-wide binary aspect of the learning will be followed by the execution examples shown in the figures. ; \ ^'ΐ: ■ ^_";;'; ■ - - ■ ^..;...

Ba show j. ";". ■ ■ ",; - ■ ^v '... - ·." . '■ """--;. ■ The Piguren 1 and 2 devices for performing the

Invention-agem Jiöen method using the arc length as a characteristic variable of the plasma torch!

Figures 3 and

Figure 5

Devices for carrying out the method according to the invention using the tear-off length of the arc as a characteristic bulb of the plasma torch;

a device for carrying out the method according to the invention using the pilot's direct current arc with a free gas outlet the Qasaustrlttsdüse Ubsritt ^ fcen VeOhselstroraes as of the plasma torch.

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In all figures, similar parts, ie parts of similar punctures »are given the same reference symbols *. .- ■ ■ _. - ν "~" ■ ■ ^v ".". "" ■ ': ■ "

FIG. I shows a device with the aid of which an object is guided at a constant distance from a surface. I denotes a low-power plasma torch which has an electrode 2 and an electrode holder 3. Between the electrode 2 and the workpiece% of the arc between the electrode 5 # 2 and the Brennerkör "burns by the pilot arc. 6

The plasma torch I is fastened in a torch bracket 7 to which the carriage 8 is connected. The slide 8 runs in a slide guide 9 with the aid of a threaded shaft 11 driven by the motor 10. The object to be guided is not shown, which is fixedly connected to the slide 8 in a manner which is insignificant in the context of the invention. The slide guide 9 is connected to a chassis which is indicated schematically by the roller 12 moving on the workpiece. The main movement direction of the chassis is perpendicular to the plane of the drawing, that of the carriage 8 and thus of the object and d @ s. Plasma burner 1 perpendicular to the surface of the memorandum piece @ a 4, as indicated by the double arrow IJ . ,

-. The arc 5 dt "plasma torch © i, .d © r © is set" fltt "r'4 * s workpiece 4 without the use of guns

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borrowed somewhat heated, is supplied from the main power source 14. The auxiliary power source 15 supplies the pilot arc 6. With the lines l6 and 17 the arc voltage of the plasma torch 1 of the control unit l8 as a control variable to * guided. The control unit 18 is connected to an adjustable setpoint generator 19. As soon as the one with the lines 16 and 17 actual value of the arc voltage taken from one differs from the setpoint set, the control element receives 20 a signal from the control unit 38 and switches the motor 10 in the direction of rotation required for the control. For this purpose, the control element 20 is in the power supply line from the motor power source 21 to the motor 10 this proportional control described succeeds in the arc length of the plasma torch I and thus the distance of the to be leading object vernier surface of the workpiece 4 very to keep exactly constant,

FIG. 2 shows a device for carrying out the method according to the invention "in which the object is to be guided along a joint 22 at a constant distance". The object may, for example, a Schweiibrenrmr Ain _s with the along the joint 22 a weld xur compound of the work pieces in this case placed 23 and 24

i The main direction of movement of the device is perpendicular to the counter plane. The controlled movement

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■ the object and the plasma torch 1, both of which are attached to the slide 8, the object, for example, via the carrier 26 -aind / runs parallel to the surface of the workpieces 23 and 24 according to the double arrow 25 in the plane of the drawing the jj device shown in Figure 2 has the same function as the corresponding Ba-U--; f! elements of the figure J. Compliance with a certain height j: of the device above the workpieces 23 and 2k is carried out by

^; the roller 12, which, however, is also supported by a complete height ■ f control in the manner of the device shown in FIG

i! ■ ■ ^: -

'can be replaced.

Is shown in Figure 3, let similar to FIG! / Direction, performed with the aid of an object in ji constant distance from a surface "In eyeletting \\ contrast to figure 1, however here the AbreiSIänge of ji Lichtboge ns as the characteristic variable des -PlesmabPenfsefo-. j 'is used for guiding the object.

With regard to the description of the structure * of the Ii ! Figure 3 illustrated arrangement is based on the description Figure 1 referenced. The setpoint generator 19 shown there is here, however, not necessary. As soon as the value of the arc voltage taken from lines 16 and 17 changes discontinuously, ie if the arc is ignited again, the control element 20 receives 18 from the control unit Signal by which the direction of rotation of the «Motora

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10 is reversed. The control member 20 is for this Purpose in the power supply line from the motor power source 21 to the motor 10. With this point control described it succeeds, the distance between the nozzle of the plasma torch 1 and the factory locomotive 4 and thus the distance to the leading Keeping the object constant from the surface of the workpiece 4 very precisely *

FIG. 4 shows a device for carrying out the method according to the invention using the abrel along the arc as a characteristic orus, in which the object is guided at a constant distance along a butt joint. The object can, for example, be a welding torch * with which a® weld seam mxp connection of the workpieces 23 and 24 is to be laid along the SfcoSfug® 22. The main direction of movement of the device is perpendicular to the plane of the drawing. The controlled movement of the object and the plasma torch 1 *, both of which are attached to the carriage 8 "the object, for example via the carrier 26", runs mainly parallel to the double arrow 25 in the plane of the drawing to the surface of the workpieces 23 and 24 Plasma torch 1 with the object b * i \ burning «arc 5 in the direction of the edge of the -Sf ^ tfug · The arc 5 goes out after exceeding the Ka & fev with the Äbreiälänge, whereby over the H@gelelnh.eit i8 -'- vmA

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Control member 20 a reversal of the direction of movement of the plasma burner 1 is caused. All other components of the device shown in FIG. 4 have the same function as the corresponding components of FIG Type of device shown in Figure 1 or in Figure 3 can be replaced.

FIG. 5 shows, similar to FIG. 4, a device with the aid of which an object is guided at a constant distance along a butt joint. In contrast to FIG. 4, however, an alternating current superimposed on the eieichetrem d @ s pilot "arc" is used as the QrHSe of the plasma torch. "

With 1 is again a plasma torch U9V, an electrode 2 and an® .Elektrod ^ atelt®! Between the electrode 2 and the torch body of the plasma torch I burns the pilot arc 6, in the case of the plasma torch, 1 is fixed in a Brentierhtlterußg T m & M which is connected to the slide 8. The slide a - S runs is ®ln®r slide guide 9 «it help a ·? vo »engine. 10. aag®teSeben®ii Oewiiad © "- well," Wicht 11 / darg "" t # falls IMT des'sJa.'ffBtranäi? object »äas in any ie '' ZnMwpJhun & mtt $ & r Zvflnäuva, ohen kind vma

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is connected to the support 26, feet. The slide guide 9 is connected to a chassis «that by slide on the Work piece calibrating moving roller 12 indicated echematically

• -

is. The main direction of movement of the chassis is perpendicular to the plane of the drawing, the direction of movement of the carriage θ and thus the object and the plasma torch 1 according to the double arrow 25 perpendicular to the main direction of movement and parallel to the surface of the workpieces 2> and 24, between where the welding joint 22 is located.

The gas outlet nozzle 5 * of the plasma torch 1 is directed at one of the two edges of the carbonization joint 22 and is located as close as possible to the surface "for example of the workpiece 23" or touches this surface lightly Inventions do not lead to the following: - the execution does not. The pilot arc 6 is supplied by the direct current source 15. In the line from the direct current source 15 to the electrode 2 there is a control unit 18.

If a superimposed alternating current occurs in the direct current circuit of the pilot arc 6 or if this disappears again »nae imoer then the case is * if the QasaustrittsdUse § ^f exceeds the edge of the workpiece 23, the control unit 18 sends a signal to a control member 20» that in the power supply line from the motor current

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source 21 «is around motor 10. At each signal, the control member 20 switches the direction of rotation of the motor 10. With this point control, it is possible to move the plasma torch 1 and thus the object at a constant distance along the prescribed path, which in this case is the edge of the workpiece 23. The object here can be a welding torch with which the workpieces 23 and Zk forming the Schvreififuge 22 are to be welded to one another.

. The inventive method for guiding a Object as contactless with the help of a plasma torch working feeler is certain because of the very hewn dependency and in the chartkterir> tables described in one Oil the plasma torch · from the distances to the given paths more accurate and accurate «The construction of a suitable device for carrying out the process * is simple and consists exclusively of components * which are based on the different» most technical fields are already in use »

12 claims 3 sheets of drawings

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Claims (1)

LINDE AKTIENGESELLSCHAFT H 68/28 " February 26, 1969 Sm / kr Claims / l. j Method for guiding an object, for example a processing machine or a welding torch, at a constant distance from and along a predetermined path with a sensor which scans the predetermined path without contact and controls the movement of the object, characterized in that a sensor with the object A connected plasma torch (1), preferably of low power, is used, the nozzle of which is kept at a constant distance from the predetermined path by influencing a motor (10) that moves the object in a controlled manner depending on characteristic (Srufien of the plasma torch (1)) 2. The method according to claim I, characterized in that daft as characteristic of the plasma torch (I) whose arc length is used, with the arc voltage in a "Begeleinheit" (18) is introduced, which in the event of deviations the Liehtbo $ enlMng # and thus the arc clamping of a «» setpoint on a control element (20) in the SUomzu- dea motors (10) works. 909845/0896 ORIGINAL INSPECTED; 1913128 LINDE AKTIENGESELLSCHAFT 3. The method according to claim 1, characterized in that the tear-off length of the arc (5) is used as the characteristic variable of the plasma torch (1), the arc voltage being introduced into a control unit (18) * the one with the tear-off or Reignition of the arc (5) associated discontinuous change in the arc voltage sends a signal to a control element (20) in the power supply line of the motor (10) and the direction of rotation of the motor (10) is switched by a switching operation of the control element (20). 4. The method according to claim l _s characterized in that only the pilot arc (6) of the plasma torch (1) brefrat that occurs as a characteristic size of the plasma torch (I with free exit of the Gn & ea from the gas from trtttsdfls® C5 ¹ } of the plasma torch (l) and alternating current superimposed on the direct current of the pilot arc (6) is used, the direct current of the pilot arc (6) being introduced into a control unit (18) which, when the superimposed alternating current occurs or disappears, sends a signal to an in the current supply of the motor . (10) lying- control element (20) gives and doodles a .- switching process of the control element j2Ql In each case the ^: ". Fcung dee motor (ΙΟ)" is umgeiseb & ranc * - ■: -. 909845/0806 ORIGINAL INSPECTED 1913128 LINDE AKTIEKQESELLSCHAFT 5 · The method according to claim 2 or 3 »characterized in that because the object is moved along a main direction of movement in an uncontrolled manner and in a controlled manner perpendicular to it. 6 * Method according to claim 5, characterized in that »dafl das Object perpendicular to the area in which the specified path and main direction of movement run is moved. 7. The method according to any one of claims 2 to ^ »characterized in that the object along a main direction of movement uncontrolled and perpendicular thereto and parallel to the area in which the specified path is the main direction of movement is moved in a controlled manner. 8. The method according to claim 5, characterized in that it is core Object in two mutually perpendicular directions with the help of « by two plasma torches and two moving the object in a controlled manner in Hotoran, independently of each other 9. The method according to Anapruch 5 or 8, characterized in that the object or one of the plaamabrennar itself is the guided object. . ■% ^: >, v V -: -. . - v ^: "^ t ■ ->: · ^v :. ^; : ''. ■ ,: ■: ' 909845/0896 1913128 LINDE AKTIENGESELLSCHAFT ■ -; * - · ■■ 10. The method according to any one of claims 1 to 9, characterized in that that the specified path is an edge, for example a welding joint. 11. Device for performing the method according to a One or more of Claims 5 to 10, characterized in that a carriage guide is provided on a chassis moving in the main direction of movement in an uncontrolled manner (9) is attached, which is movable perpendicular to the main direction of movement by a controlled motor (10) and guides the object with the slide (8) carrying the plasma torch (1). 12.Vorrichtung according to claim 11 for performing the method according to claim 8, characterized in that a second slide guide is perpendicular to the first slide guide Slide guide is provided, which has a second slide th with a second plasma torch, the first slide guide being part of the second slide is. 909845/0896