Nozzle for processing workpiece e.g. by laser beam - consists of nozzle body with sensor element of e.g. copper@ attached to insulating body for contactless measurement

The invention relates to a nozzle for machining a workpiece in accordance with the preamble of claim 1. Such a nozzle is part be already with the prior art (JP 21 37 686 A in "patent abstracts of Japan ", 1990, Vol. 14 / No. 375, Sec. M-1010) and contains

<ul><li>- A nozzle body,</li><li>- A arranged at the tip of the nozzle body sensor element for non-contact measurement, for example the distance between rule it and the workpiece or for process control,</li><li>- A signal line terminal,</li><li>- A further line connection and </li><li>- A first line, via which the sensor element with the Signallei device connection is in contact.</li></ul>

If the nozzle fixed to a tool, so it is possible that Tool relative to position m workpiece to the workpiece in To edit appropriately. Positioning is about ei ne usually means that the measured distance between Sensorele ment and workpiece as an actual receiving and the position of the nozzle in Ab a function of a comparison of the actual value with a predetermined desired value controls.

The tool may, for example, a laser cutting unit for generating be a laser beam, with which cut the workpiece or in can be treated otherwise.

The distance between the sensor element and the workpiece is on measured capacitively, for what purpose and via the signal line connection the first line, a measuring voltage is applied to the sensor element. About the other lead terminal, a shield potential to the SI senkörper be applied to the measurement voltage to external A rivers to protect. The sensor element is compared with the nozzle body electrically isolated.

The signal line connection is, for example, to the inner conductor of a Coaxial cable connected, the outer shield conductor to the other Line terminal is connected. The other end of the coaxial cable connected to a sensor electronics to produce the Meßspan tion is, which is an alternating voltage. This measurement wechselformige voltage is applied to the inner conductor of the coaxial cable. In case of a active shielding reaches the wechselformige measuring voltage also to the Shield conductor, for. Example, via a capacitor and an amplifier with the Gain V =. 1

In laser cutting, it may happen that due to vibrations during the machining of the workpiece loosens the sensor element, forming the tip of the nozzle and consists for example of copper. In the case, there is a poor cut quality, and the distance control may become unstable by a resulting poor contact.

If on the other hand, an operator forget when changing the nozzle body, the sensor electrode hineinzuschrauben in the tip of the nozzle, so can by resulting splash in the machining of the workpiece by means a laser beam damage the focusing lens occur the most The nozzle inlet is disposed. Finally, without any sensor electrode Distance control possible.

The invention has for its object, the nozzle of the initially genann educate th kind so that electronically a looser reveal certain seat or an absence of the sensor element.

The solution of the problem is in the characterizing part of patent demanding 1 indicated. Advantageous embodiments of the invention are in the dependent claims.

The nozzle according to the invention is characterized in that

<ul><li>- The sensor element lie at a distance from the first line ing point to a second line in contact and</li><li>- The second line via a resistor with the further line connection is connected.</li></ul>

The sensor electronics can therefore easily the Verbindungszu was thereby detect between the sensor element and the nozzle body, that it checks whether the circuit between the first conduit and the second line is closed by means of the sensor element or not. To this end, they may have a sense current on the inner conductor of the Coaxial cable, the signal line terminal, the first line, the Sen sensor element, the second line, the resistor, the other Leitungsan circuit and, for example, send the shield conductor of the coaxial cable, such that this current query the wechselformige measuring voltage for He mediation of the distance between the sensor element and workpiece not be influenced. For example, measuring voltage and wechselformige Abfra gestrom be periodically applied sequentially, or it may be to He generation of the query stream, a query-DC voltage of alternating shaped measuring voltage are superimposed. Here, the time in which the Query current flows, be extended so far that even Wackelkontak te Kings are reliably detected between the sensor element and the nozzle body NEN. If, during the query time is an open circuit Detek Animal T, the sensor electronics generate an error or alarm signal at least lead to the elimination of the laser unit. Of course can be achieved by this error or alarm signal also the entire plant Shut down.

According to an advantageous development of the invention the nozzle has to additionally a resistor between the signal line connection and the another line connection.

In this case can be described by the sensor electronics two error signals create, and by monitoring the size of the query stream. For example, if the nozzle is not connected to the sensor electronics so can no sensing current flow, resulting in an error signal leads, through which the entire system is shut down. However, if the nozzle connected to the sensor electronics, but lacking the sensor element, or is a loose connection between the sensor element and the nozzle body before, so the sense current flows only through the between the Signalleitungsan circuit and the other line terminal connected resistor what leads to a further error signal by which at least the laser cutting unit is turned off, to safely prevent the case game because of a missing sensor element no damage to the Optics by splashes occurring during laser cutting at the entrance of the nozzle.

According to an advantageous embodiment of the invention is the Sensorele held management at the top of an insulating body, which on the nozzle body is attached, wherein the first and the second line through the insulation bodies are guided. Here, the first and the second line extended at the top of the insulator to contact areas.

In the operating state, the sensor element generally pressed firmly against these contact surfaces so that a good electrical contact between ih NEN and the sensor element is present. However, once the Sensorele ment even ge due to vibrations in the workpiece machining slightly loosens, the electrical connection between it and the interrupted once the first or second line, so that a derarti ger fault condition can be detected quickly.

included According to another advantageous embodiment of the invention the first and the second line in the region of the nozzle body each have a insulated, resilient contact portion, said contact portions press against the corresponding line sections in isolation body run.

often Applications for a given nozzle body are several Sensorele elements to choose from, each with it a special Isola can connect tion body. is connected to the exchange of the sensor elements therefore connected replacement of the insulation body so that the sen case proper wiring between the nozzle body and insulation body extending portions of the first and second line must be ensured. To this end, the resilient Kon care Diplomatic sections which are isolated in the nozzle body and fixed.

The insulating material can for example be made of ceramic and its tip have an internal thread, into which the düsenformige Sen is screwed sensor element. The extended contact surfaces of he art and second line can thereby also on opposite Sides of this internal thread are. It is also a corresponding de silvering the end face of the ceramic part.

According to another embodiment of the invention, the sensor element also in the front end of a surface-insulated metal sleeve a be screwed to the outer circumference two mutually beabstan Contact finished parts are fixed, which the front end against a flange Sensor element hit.

Such a structure leads to particularly slender nozzle as in needed example for the three-dimensional workpiece processing are. In this case, a contact part with the signal line connection connected, while the other contact portion of the resistor with the another conduction terminal connected. Both are contact parts slightly above the face of the metal sleeve out so perfect electrical connection to the sensor electrode and the sensor element is possible.

According to yet another embodiment of the invention is the Sensorele ment in the front end of a surface-insulated metal sleeve set at the outer periphery of two spaced apart Kon clock parts are fixed, the front end against a flange of Sensorele beat mentes, wherein the sensor element by means of a oberflächeniso profiled coupling element is held, which with the outside of Kon clock parts engaged. Preferably, the metal sleeve and the Union member is made of anodized aluminum. so wear on its entire surface an electrically insulating layer. there can be designed as a union nut, the coupling element, the on the outer side of the contact parts is screwed. An anodized coating is also present in the area of ​​the internal thread of the union nut. in the the latter case, the sensor element in the metal sleeve single Lich inserted or be screwed. The Überwurfele ment may also have a Teflon coating or ceramic coating tra gene.

The invention will nä below with reference to the drawing ago described. Show it:

<b>Fig.</b> 1 a nozzle according to a first embodiment with egg nem resistance for sensor element detection,

<b>Fig.</b> 2 is a nozzle according to a second embodiment with a resistance to the sensor element detection and egg nem resistance to nozzle identifier,

<b>Fig.</b> 3 is a nozzle body having resilient contact portions for the first and second conduit,

<b>Fig.</b> 4 a nozzle body having an attached sensor element and

<b>Fig.</b> 5 In the left section of a nozzle body having been schraubtem sensor element and egg in the right section NEN nozzle body having a sensor element of a Nut is held.

The <b>Fig.</b> 1 shows the basic structure of a nozzle according to a first Embodiment of the invention.

The nozzle <b>1</b> includes a nozzle body <b>2</b>Which, for example, be made of metal stands. At the top of the nozzle body<b>2</b> is an insulating body <b>3</b> BEFE Stigt, such as a ceramic body. This insulating body<b>3</b> wearing again at its tip, a sensor element <b>4</b>, For example, of Copper is prepared. The ceramic body<b>3</b> are nozzle body <b>2</b> and sensor element <b>4</b> insulated from each other.

The entire nozzle <b>1</b> has an internal channel, not shown, by to a laser beam, and optionally processing gases for machining processing a workpiece to pass through.

A coaxial jack <b>5</b> is located on a side wall of Sen sorkörpers <b>2</b>, The coaxial jack<b>5</b> has a Signalleitungsan conclusion <b>6</b> and another line terminal <b>7</b> on. With the coaxial wall jack <b>5</b> is externally an unillustrated coaxial ver bindable, is connected to one end of a coaxial cable, whose the other end is connected to the sensor electronics. The center conductor of the Coaxial cable is thereby the signal line connection <b>6</b> in contact, while the shielding of the coaxial cable with the other Leitungsan conclusion <b>7</b> communicates. The shield can, for example, are ground potential or active potential, as already mentioned.

For the capacitive measurement of the distance between the sensor element <b>4</b> and the workpiece by the sensor electronics via the center conductor of the coaxial cable and via the signal line connection <b>6</b> a change formiges measuring signal (detection voltage) to the sensor element <b>4</b> transmitted, the is evaluated in a conventional manner. For example, can be his capture amplitude for determining distance, if there is a fixed frequency having.

The transmission of the measurement signal from wechselformigen Signalleitungsan conclusion <b>6</b> the sensor element <b>4</b> takes place via a first line <b>8th</b>, which the signal line connection <b>6</b> the sensor element <b>4</b> extends and the egg NEN portion within the nozzle body <b>2</b> and the other part within the insulator <b>3</b> runs. Since the insulation body<b>3</b> from Düsenkör by <b>2</b> is removable, located at the junction of a first contact <b>9</b> for connecting the two line portions of the first Lei tion <b>8th</b>, At the top of the insulator<b>3</b> is the first line <b>8th</b> to a contact area <b>10</b> expanded to provide good electrical contact to sensor element <b>4</b> be able to produce.

The sensor element <b>4</b> is at a distance from the first line <b>8th</b> lie ing point to a second line <b>11</b> in contact, also in the Iso lationskörper <b>3</b> runs. This second line<b>11</b> is at the top of Iso sweep solid <b>3</b> to a second contact surface <b>12</b> expanded to a gu th contact with the sensor element <b>4</b> be able to produce. first and second contact surface <b>10</b> and <b>12</b> best example, of silver hen. The sensor element<b>4</b> forms practically a bridge between these two contact surfaces <b>10</b> and <b>12</b>,

The other end of the second conduit <b>11</b> is a second contact <b>13</b>That between the nozzle body <b>2</b> and angeord the insulating body is net, in the nozzle body <b>2</b> ushered and is up there with one end a resistor <b>14</b> connected. The other end of this resistor<b>14</b> is connected via a further section of the second conduit <b>11</b> for example with the other line connection <b>7</b> the coaxial jack <b>5</b> verbun the. Instead of the second line terminal<b>7</b> , this end of the Lei tion <b>11</b> directly to the nozzle body <b>2</b> be connected if this consists of metal and is also at ground or shield potential.

In order to detect whether the sensor element <b>4</b> in prescribed manner the insulation body <b>3</b> is connected is on the sensor electronics the signal line connection <b>6</b> a sense current (sensing voltage) LOVED fert. If a proper connection of the sensor element<b>4</b> With the insulation body <b>3</b> before, so this query current flows from Signallei device connection <b>6</b> via the first line <b>8th</b>, The sensor element <b>4</b>, the second management <b>11</b> and the resistor <b>14</b> back to the further Leitungsan conclusion <b>7</b> the coaxial jack <b>5</b>, Since the magnitude of the resistance<b>14</b> and which are known to the scanning voltage, can in this way verify that a proper electrical contact between the sensor element <b>4</b> and the first contact surface <b>10</b> or the first line <b>8th</b> is available. Such contact is necessary in order a proper be able to make free adaptive cruise control, or more generally a one perform flawless distance measurements or process control to Kings NEN.

Has contrast due to vibrations or other phenomena that sensor element <b>4</b> loosened, or it is completely out of the insulating body <b>3</b> dropped out, so the first line are <b>8th</b> and the second line <b>11</b> no longer by the sensor element <b>4</b> bridged, so that the query current can no longer flow. This condition is caused by the Sensorelek tronics detected, which then generates an error or alarm signal. The ses alarm signal can be used, at least the laser trainees turn, to avoid damaging the workpiece or other components for example to prevent the optics above the nozzle.

As mentioned above, the query DC influence (query DC) and the measurement signal wechselformige mutually not because the measured capacitance between the signal line connection <b>6</b> or Mittellei ter of the coaxial cable and the workpiece to be machined is located, while the resistance ultimately between the center conductor of the coaxial cable or the signal line connection <b>6</b> and the other line terminal <b>7</b> or. Shieldwires comes to rest. Since the distance measurement of only the alternately shaped measuring signal is generated, the filtered accordingly may be, it is by the signal line connection <b>6</b> lying DC voltage or scanning voltage not affected.

In the <b>Fig.</b> 2 is a nozzle according to a second exemplary embodiment of the invention represented. The same parts as in<b>Fig.</b> 1 are given the same loading numerals and will not be described again.

In the nozzle according to <b>Fig.</b> 2 is located between the Signalleitungsan conclusion <b>6</b> and the other line terminal <b>7</b> the coaxial jack <b>5</b> an identification resistor <b>15</b>, Practically parallel to the series circuit tion is that of resistance <b>14</b> and a switch is obtained by the Elements <b>4</b>. <b>10</b> and <b>12</b> is formed.

By combining the resistors <b>14</b> and <b>15</b> can be various ne state of the nozzle determine, by checking the Abfra ge-DC current through the sensor electronics.

If no nozzle <b>1</b> to the coaxial cable via the coaxial jack <b>5</b> connected, so no current query what veran the sensor electronics flows caused to generate an alarm signal and shut down the entire plant. is however, the nozzle <b>1</b> ver to the coaxial cable or the sensor electronics prevented, but has the sensor element <b>4</b> the insulating body <b>3</b> ge loose or broken away from this, so is a proper distance measurement or distance control is no longer possible. In this case, the size of the sensor current only through the identification resistor <b>15</b> be True, so that can produce a second error signal, the error to abnormal operation state of the sensor element <b>4</b> indicates. In ordnungsgemä SSSR connecting the sensor element <b>4</b> and insulating body <b>3</b> on the other hand the sensing current through the combination of resistors <b>14</b> and <b>15</b> firmly placed, so that no error signal is generated in this case.

As already mentioned, can be of the insulation body <b>3</b> from the nozzle body <b>2</b> lose weight, so that contacts for connecting the respective Leitungsab sections of the first and second line <b>8th</b> or. <b>11</b> must be present. These contact portions through the contacts <b>9</b> and <b>13</b> formed that can be designed as resilient. It can therefore be ver different insulation body <b>3</b> with different sensor elements <b>4</b> at the nozzle body <b>2</b> start, the insulating body <b>3</b> at the SI senkörper <b>2</b> opposing surface are all identical.

The <b>Fig.</b> 3 shows the more detailed structure of the nozzle body <b>2</b>, Same parts as in the <b>Fig.</b> 1 and 2 are provided with the same reference numerals.

The nozzle body <b>2</b> consists essentially of a conically extending the nozzle part <b>16</b>Which consists of electrically conductive material, e.g. is made of steel. On the outer periphery of the thicker end of Dü senteils <b>16</b> There is a mounting sleeve <b>17</b>Which externally cylindrical is formed and an outer thread <b>18</b> wearing. nozzle part<b>16</b> and fastening supply sleeve <b>17</b> are fixedly interconnected, so that the entire nozzle over the external thread <b>18</b> can be screwed into a holder.

At the tip end of the nozzle portion <b>16</b> located peripherally a ring shaped channel <b>19</b>, Which serves to receive electrical leads. In the outer wall <b>20</b> the annular channel <b>19</b> the coaxial socket <b>5</b> (please refer <b>Fig.</b> 1 and 2) are used, the outside with a Coaxial cable is connected. The annular channel<b>19</b> also made of elec trically conductive material, said further line connection <b>7</b> the Ko axialsteckerbuchse <b>5</b> directly to the outer wall <b>20</b> in electrical Contact is. In this manner, the shield potential to the ringförmi gen channel <b>19</b> and via this to the nozzle part <b>16</b> placed. nozzle part<b>16</b> and annular channel <b>19</b> are, for example, an external thread <b>21</b> of the nozzle member <b>16</b> in electrically conductive connection, to which the ringför shaped channel <b>19</b> is screwed.

In the bottom surface <b>22</b> the annular channel <b>19</b> the contacts <b>9</b> and <b>13</b> obliquely downward pointing admitted. The contacts<b>9</b> and <b>13</b> are ge compared to the annular channel <b>19</b> or the bottom surface <b>22</b> electric isolated, via insulating sleeves <b>23</b>In which the contacts <b>9</b> and <b>13</b> to come to lie. The contacts<b>9</b> and <b>13</b> assign to her the nozzle tip facing end face respectively a resilient contact element <b>24</b> On that in the axial direction of the contacts <b>9</b> and <b>13</b> is slidable.

At the contact elements <b>24</b> opposite end faces of the Contacts <b>9</b> and <b>13</b> these are the portions of first and second management <b>8th</b> and <b>11</b> connected. The section of the line<b>8th</b> in <b>Fig.</b> 3 is un indirectly to the signal line connection <b>6</b> the coaxial jack <b>5</b> connected, while the portion of the conduit <b>11</b> in <b>Fig.</b> 3 with one end of in <b>Fig.</b> 3 resistance not shown <b>14</b> connected is. The rest the electrical circuit is either in accordance with the <b>Fig.</b> 1 or <b>Fig.</b> 2 built.

At the top of the nozzle body <b>2</b> is an approach <b>25</b> availability of the insulation body <b>3</b> can be placed. Furthermore, there is a cylindrical approach <b>26</b> on the lower side of the bottom surface <b>22</b>, This approach<b>26</b> has an external thread <b>27</b> onto which a in <b>Fig.</b> 4 Überwurfmut shown ter can be screwed to the insulation body <b>3</b> on the nozzle body <b>2</b> to be consolidate, as will be seen.

The <b>Fig.</b> 4 shows the nozzle body <b>2</b> after <b>Fig.</b> 3 with attached thereto Sen sensor element <b>4</b>,

The nozzle body <b>2</b> is to the embodiment <b>Fig.</b> 4 example , by means of a flange <b>28</b> maintained, which on the external thread <b>18</b> is screwed after the nozzle body with its mounting shell <b>17</b> through a suitable opening, not shown, of a Trägerele ment has been pushed.

As the <b>Fig.</b> 4 reveals, is on the approach <b>25</b> of the nozzle body <b>2</b> of the insulation body <b>3</b> attached, which consists for example of ceramic. With Aid of a union nut <b>29</b> is this insulation body <b>3</b> against the nozzle body <b>2</b> or approach <b>25</b> drawn, including the union nut <b>29</b> about a flange <b>30</b> the insulator <b>3</b> engages and on the other hand on the external thread <b>27</b> the cylindrical extension <b>26</b> is screwed. Of the insulation body <b>3</b> has an axial through bore which at its Tip with an internal thread <b>31</b> is provided. In this internal thread<b>31</b> is provided with a corresponding external thread, the sensor element <b>4</b> into screwed, which consists for example of copper. The sensor element<b>4</b> has an axial through opening <b>32</b> through which the laser beam and optionally pass a processing gas.

The electrical connection between the contact elements <b>24</b> the Kon contacts <b>9</b> and <b>13</b> on the one hand and the sensor element <b>4</b> on the other hand takes place through portions of the first and second line <b>8th</b> and <b>11</b>That within the insulator <b>3</b> extend. To this end are intra half of the insulation body <b>3</b> For example, each opposite the sides of the hollow channels, through which the lines <b>8th</b> and <b>11</b> pulled through are. The outlet surfaces of the hollow channels, the lines<b>8th</b> and <b>11</b> extended to contact surfaces which in <b>Fig.</b> 4 by the reference numerals <b>10</b> and <b>12</b> are designated. Also, at the opposite ends of this line portions may be present such contact surfaces against which then the contact elements <b>24</b> to press. The contact surfaces<b>10</b> and <b>12</b> be can be found at the lower end of the insulating body <b>3</b> and come in contact with the sensor element <b>4</b>When fixed in the internal thread <b>31</b> is screwed and against the face of the insulation body <b>3</b> suppressed. If the sensor element<b>4</b> Loosen any reason or the insulating body <b>3</b> fall, will open the line contact between the sensor element <b>4</b> and the contact surfaces <b>10</b> and <b>12</b>what leads to the interruption of the circuit for the current query. It will then generates the aforementioned error signal.

The error signal is also generated when, for example, by mistake Lich the nozzle is driven onto an obstacle, and as a result, the Ke ramikkörper <b>3</b> breaks.

A further embodiment of an inventive nozzle is in of the <b>Fig.</b> 5 is shown.

In this embodiment, a sensor element <b>4</b>a in the stirnseiti ge end of a surface-insulated metal sleeve screwed that the numeral <b>33</b> wearing. To this end, wearing a neck<b>4</b>b of Sensore lements <b>4</b>a an external thread <b>34</b>That in an internal thread <b>35</b> the metal shell <b>33</b> accesses. On the outer circumference of the metal shell<b>33</b> are per se opposite sides of metallic contact parts <b>36</b>. <b>37</b>Which against each other insulated and the metal sleeve <b>33</b> are firmly connected. The Kon clock parts <b>36</b> and <b>37</b> are also with respect to the metal sleeve <b>33</b> electrically iso lines, in turn, relative to the sensor element <b>4</b>is a electrically isolated, namely by the insulating surface coating, the Example as may be anodized layer when the element <b>33</b> made of Aluminium consists. The metallic contact parts<b>36</b> and <b>37</b> project somewhat over the front end face of the metal sleeve out and strike a flange <b>4</b>c of the sensor element <b>4</b>a, if this all in the metal sleeve <b>33</b> is screwed. Further, the metallic contact parts<b>36</b> and <b>37</b> respectively via the first and second lines <b>8th</b> and <b>11</b> in the same Way connected, as in the <b>Fig.</b> is 1 and the second Dissolves the sensor element <b>4</b>a from the metal sleeve <b>33</b>So lifts the flange <b>4</b>c of the tips of the contact parts <b>36</b> and <b>37</b> from what the circuit refraction results, and thus for generating the aforementioned errors signal.

The metallic sleeve <b>33</b> themselves can also shield or ground are, as well as an outer sleeve <b>38</b>Which sleeve the <b>33</b> and the contact parts <b>36</b> and <b>37</b> concentrically surrounds. To stabilize the assembly in within the outer sleeve <b>38</b> can between you and the contact parts <b>36</b> and <b>37</b> a further sleeve <b>39</b> be present, the electrically isolate a de surface coating contributes to a short circuit between the externa ßeren sleeve <b>38</b> and the contact holders <b>36</b> and <b>37</b> to prevent. These further sleeve <b>39</b> can also be an anodized aluminum sleeve the gap between the outer contact parts <b>36</b> and <b>37</b> and outer shell <b>38</b> fills.

The contact parts <b>36</b> and <b>37</b> For example, on the outer periphery the metal sleeve <b>33</b> be glued.

In the area of ​​the sensor element <b>4</b>A shows the <b>Fig.</b> 5 on the right side a white tere embodiment of the invention. Thus, the sensor element<b>4</b>a through a union nut <b>40</b> against the tip of the barrel <b>33</b> to be pulled. There to engage behind the coupling nut <b>40</b> the flange <b>4</b>c and is a Female thread on a tip-sided external thread not shown the metallic contact parts <b>36</b> and <b>37</b> screwed on. The union mother <b>40</b> carries at least in the contact area with the sensor element <b>4</b>a and the contact parts <b>36</b> and <b>37</b> an electrically insulating Oberflä chenbeschichtung, for example, an anodized layer when aluminum minium is. When using the coupling nut<b>40</b> , the Sen sensor element <b>4</b>a only in the sleeve <b>33</b> be plugged in without then there a thread must be present.

In the <b>Fig.</b> 5 is a workpiece by the reference numeral <b>41</b> provided. A La serstrahl permeated the entire nozzle and passes through a channel <b>42</b> out the tip of the sensor element <b>4</b>a from. The laser beam transmits the reference sign L. Its focusing optics (not shown) located in Entrance area of ​​the nozzle.