Fully automated process for the production of a measuring electrode for electrochemical measurements in a measuring fluid with a force-locking electrically conductive connection in the tubular body by means of shrink body pressing

Abstract

Fully automated process for producing a measuring electrode for electrochemical measurements in a measuring fluid, wherein the following steps are carried out in the process: (a) a first gripper (11) places a sensor material body (5) into a joining receptacle (10), (b) the sensor material body (5) is fixed to the joining receptacle (10) by means of suction force, (c) a second gripper (12) positions a piece of line (6) made of electrically conductive material relative to, preferably on, the fixed sensor material body (5), (d) the positioned line piece (6) is materially connected to the fixed sensor material body (5) by means of a joining tool (20) in order to obtain a sensor assembly (5, 6), (e) a tubular body (1) having an end opening (1a) in a front tubular body region is held by means of a chuck (15), (f) the sensor assembly (5, 6) and / or the tubular body (1) is / are positioned such that the sensor material body (5) faces the opening (1a) and the line piece (6) projects through the opening (1a) into the tubular body (1), (g) the tubular body (1) is connected in the region of the opening (1a) by means of a melt connection (S1) and / or material bond with the sensor material body (5) in a fluid-tight manner around the opening (1a), (h) a connecting cable (7) made of electrically conductive material and a shrink body (8) are inserted into a tubular auxiliary tool (23), (i) the auxiliary tool (23) with the connecting cable (7) and the shrink body (8) are inserted into the pipe body (1) which is open at a rear end and moved in the direction of the cable section (6), thereby bringing the connecting cable (7) and the shrink body (8) into overlap with the cable section (6), (j) wherein the auxiliary tool (23) surrounds the connecting cable (7) and the shrink body (8), preferably shrink tubing, and (k) the shrink body (8) is shrunk in the overlap by heating, so that the shrunken shrink body (8) presses the cable piece (6) and the connecting cable (7) together lengthwise and thereby connects it in an electrically conductive manner.

Description

[0001] The invention relates to a fully automated method for producing measuring electrodes, in particular redox electrodes but also other types of measuring electrodes, for example chlorine electrodes, hydrogen peroxide (H2O2) electrodes, corrotrodes, titration electrodes and other types of measuring electrodes for potentiometric or amperometric measurements.

[0002] DE 10 2012 101 004 A1 discloses a reference electrode for use in electrochemical measuring systems. The electrode comprises a housing with a chamber filled with an electrolyte, in which a potential-forming element is arranged so that the electrolyte wets the potential-forming element. To dissipate the potential, an electrical conductor is connected to the potential-forming element; it is mentioned that a shrink tube can serve as a connection point.

[0003] EP 0 171 959 A2 discloses an electrode with a sensor element made of antimony and antimony oxide. The sensor element is connected to a connecting lead via a graphite filament conductor. The graphite filaments are wound around the sensor element or coated with the sensor element material, thereby electrically connecting it to the sensor element at one end. At the other end, the graphite filament conductor is connected to the connecting lead. For insulation, a shrink tube surrounds the section where the sensor element is connected to the conductor.

[0004] CN 101 419 185 A discloses a CO2 electrode in which a connecting lead is soldered to a sensor material body. A shrink tube surrounds the solder joint and an adjoining section of the connecting lead.

[0005] Other measuring electrodes used for electrochemical measurements have a tubular body made of glass or plastic and a sensor material body arranged on the tubular body. The sensor material body is usually arranged at one end of the tubular body. The sensor material body is electrically connected to a connection area of ​​the measuring electrode through the hollow tubular body by means of a connecting line. Such measuring electrodes are disclosed, for example, in DE 20 2011 101 241 U1. During production of the measuring electrode, the sensor material body and the connecting line are connected to one another in a first step. The connecting line is then threaded through an opening in a tubular body blank. In a further step, the sensor material body is joined to the tubular body blank in the region of the opening, for example by melting the sensor material body.The manufacture of the joint between the sensor material body and the tube body is problematic due to the typically thin and / or flexible connecting cable that must be threaded into the tube body blank. Therefore, such measuring electrodes are manufactured using manual labor.

[0006] It is an object of the invention to further automate the production of measuring electrodes.

[0007] The object is achieved by a method according to claim 1.

[0008] A measuring electrode suitable for electrochemical measurements in a measuring fluid, which can be produced using the method, comprises a tubular body, a sensor material body arranged on the tubular body, and a connecting line electrically connected to the sensor material body. The connecting line extends within the tubular body. It electrically connects the sensor material body to a connection area of ​​the measuring electrode. The connection area serves to connect the measuring electrode to an external operating device, for example, a measuring device, monitoring device, control device, or control device.

[0009] The sensor material body is provided with a line piece for dissipating the electrical potential of the sensor material body. The line piece is electrically conductively connected to the sensor material body and projects from the rear of the sensor material body into the tubular body. The connecting line overlaps longitudinally with the line piece in the tubular body and is electrically conductively connected, expediently with a tensile strength, to the line piece in the overlap area. Due to the division of the electrical connection into a connecting line and a line piece projecting from the sensor material body into the tubular body, which can be significantly shorter than the connecting line, the joining of the sensor material body and the tubular body is facilitated. When positioning the sensor material body and the tubular body, there is no need for a comparatively long and correspondingly flexible orA flexible connecting cable can be threaded through a narrow opening in the tubular body in order to join the sensor material body to the tubular body with the connecting cable threaded in. The invention makes it easier or even possible for the first time to automate the joining process, including the insertion of the cable section. Due to its short length, with which it protrudes from a rear side of the sensor material body, the cable section is so stiff that when the sensor material body is positioned at the opening in the tubular body, the cable section is positioned at the same time, i.e. it protrudes into the tubular body. The cable section does not have to be positioned specifically for joining, for example by being laboriously threaded through the opening in the tubular body. The cable section can protrude from a rear side of the sensor material body, in particular orthogonally to the rear side.

[0010] The invention relates to a method in which a sensor assembly comprising a sensor material body and a conductor piece is provided or produced in the method. The conductor piece is electrically conductively connected to the sensor material body and protrudes from it on a rear side. The sensor material body is joined to the tubular body so that the conductor piece protrudes into the tubular body in the joined state. A connecting cable made of electrically conductive material is inserted into the tubular body until it overlaps with the conductor piece. The connecting cable is electrically conductively connected to the conductor piece in the overlap by a force-fitting connection.

[0011] Because of the frictional connection, a material-to-material connection can be dispensed with, although an additional material-to-material connection should not be ruled out from the outset. Soldered and welded connections have been common practice so far. When the sensor material body and the connecting cable are made of dissimilar materials, soldered connections are more common. Soldered and sometimes welded connections are cumbersome because, in order to connect them, not only the respective sensor material body and the connecting cable but also the solder or welding material must be fed in and positioned. The frictional connection allows for flexible material selection. For example, the cable section can be made of a first metal and the connecting cable of a different, second metal. It is expedient if the cable section is made of platinum or gold and the connecting cable of a cheaper precious metal, such as silver.When reference is made to “metal” or a specific metal, this also includes metal alloys containing the respective metal as a base metal.

[0012] The frictional connection is created by means of a shrink body that surrounds the cable section and the connecting cable in the overlap and, in the shrunken state, forms an electrically conductive connection in the frictional connection.

[0013] More preferably, the frictional connection is achieved by means of a shrink body, which is provided in addition to the cable section and the connecting cable. The shrink body can, in particular, be a shrinkable hollow profile. A shrink tube is particularly suitable. In the overlap, the cable section and the connecting cable are in longitudinal contact and are pressed together by the shrink body, which surrounds the cable section and the connecting cable in the overlap area, thus securely holding them in contact.

[0014] The invention offers further advantages in terms of manufacturing: the contacting can be carried out more easily by automated force-locking than by welding or soldering the cable section and the comparatively long connecting cable. Another advantage is that the shrinking process can be carried out simultaneously in a furnace with multiple assemblies, each consisting of a tubular body and a joined sensor material body.

[0015] A fully automated production of a measuring electrode comprises the provision of a sensor assembly consisting of a sensor material body and a lead piece, and the joining of the sensor assembly and the tube body. In the method, a first gripper positions the sensor material body on a joining receptacle. The sensor material body is fixed to the joining receptacle by suction force. The sensor material body rests with a front side on the joining receptacle and is sucked onto the joining receptacle at the front. The joining receptacle has a system for the sensor material body and, in the region of the system, a suction opening for sucking in the sensor material body. In a further step, a second gripper positions a lead piece relative to the fixed sensor material body; preferably, the second gripper positions the lead piece on, i.e. in contact with, the fixed sensor material body.In a further step, the positioned piece of cable is electrically connected to the fixed sensor material body by means of a joining tool.

[0016] The sensor assembly comprising the sensor material body and the line piece is joined to the tubular body. The tubular body is provided with a front opening in the front region of the tubular body. For joining, the sensor assembly and / or the tubular body is / are positioned relative to one another in a joining position. During joining, the tubular body is held by a chuck, advantageously in a horizontal orientation. In the joining position, the rear side of the sensor material body faces the front opening of the tubular body, and the line piece protrudes through the opening into the tubular body. In the region of the opening, the tubular body is connected to the sensor material body in a fluid-tight manner around the opening by means of a fusion bond and / or a material bond. The material bond can be an adhesive bond, for example. The fusion bond can involve a direct material bond between the sensor material body and the tubular body.

[0017] The assembly thus obtained, consisting of the tubular body and the sensor assembly, is supplemented by the connecting cable, as explained above, whereby the contacting by means of force-locking can follow as part of a continuous sequence of steps or only after the assembly consisting of the tubular body and the sensor assembly has been temporarily stored.

[0018] As far as the sensor assembly is concerned, the conductor piece can be butt-fitted with one end against the rear side of the sensor material body and joined to the sensor material body at the end. More preferably, the conductor piece is electrically connected to the sensor material body in a first conductor section and comprises a second conductor section that is inclined toward the first conductor section and protrudes from a rear side of the sensor material body. The conductor piece can be placed lengthwise against the rear side of the sensor material piece, fixed in this relative position, and joined to the sensor material body in a materially bonded and thus electrically conductive and mechanically secure manner using a joining tool in the region of the applied first conductor section.The second line section can be erected in the applied state before, during or, more preferably, after joining relative to the sensor material body so that it points at least substantially orthogonally to the back of the sensor material body.

[0019] The sensor assembly consisting of the sensor material body and the lead piece can be umbrella-shaped or nail-shaped.

[0020] An embodiment of the invention is explained below with reference to the figures. They show: Fig. 1 a measuring electrode with a tubular body and a sensor material body, which is contacted with a connecting cable via a cable piece, Fig. 2 a front tubular body area with the joined sensor material body and a contact area of ​​the cable piece and connecting cable, Fig. 3 the sensor material body with the joined line piece, Fig. 4 a first gripper during positioning of the sensor material body on a joining holder, Fig. 5 a second gripper when positioning the cable piece on the sensor material body, Fig. 6 a joining tool when joining the cable piece and the sensor material body, Fig. 7 an interaction of the second gripper and joining tool when erecting the line piece relative to the sensor material body, Fig. 8 a transfer of the sensor assembly consisting of sensor material body and cable piece to a third gripper, Fig. 9 positioning of sensor assembly and pipe body for joining, Fig. 10 a melting device when joining the tube body and sensor assembly, Fig. 11 the insertion of the connecting cable and the shrink body into the pipe body, Fig. 12 the shrink body and an auxiliary tool and Fig. 13 the auxiliary tool in a position inserted into the pipe body in which the connecting cable overlaps the cable section lengthwise and is surrounded by the shrink body in the overlap.

[0021] Fig. Figure 1 shows a measuring electrode, for example, a redox electrode, in a longitudinal section. The measuring electrode is part of a single-rod measuring chain, which includes the measuring electrode and a reference electrode in an integrated design. The reference electrode is not shown. Fig. Figure 1 shows only the container for an electrolyte and a discharge system for the reference electrode. The measuring chain further comprises a connection device via which the measuring chain can be connected to a display device, monitoring device, or other external operating device related to the measuring chain.

[0022] The measuring electrode comprises a tubular body 1, which is double-walled to maintain the single-rod measuring chain with an outer tube 2 and an inner tube 3. The inner tube 3 surrounds an inner cavity H I . The outer tube 2 surrounds the inner tube 3 and an outer cavity H A , which is limited internally by the inner tube 3. The outer cavity H A serves to hold the electrolyte and the reference electrode's conduction system. It is ring-shaped and closed at the front of the tubular body. The tubular body 1 is closed at its rear end by both cavities H I and H A open and is sealed with the connection device after the reference electrode is completed. The connection device thus serves not only for the electrical connection of the measuring and reference electrodes, but also for sealing tubular body 1.

[0023] A sensor material body 5 is arranged in the front tubular body area, in this embodiment at the front end of tubular body 1. The sensor material body 5 is fused into the material of tubular body 1 and / or remelted with the tubular body material, i.e., joined to tubular body 1 by means of a fusion bond. The sensor material body 5 forms the front end of the measuring electrode in the form of a measuring tip. It is made of a metal, preferably platinum or gold, or, for example, silver or titanium. As already mentioned at the beginning, this also includes corresponding metal alloys.

[0024] Fig. 2 shows the front tubular body area of ​​the measuring electrode in the same longitudinal section as Fig. 1. The fusion joint is designated S1. At the inner cavity H I facing rear side, a wire-shaped line piece 6 protrudes from the sensor material body 5 into the cavity H IThe electrical potential of the sensor material body 5 is derived via the line section 6 and a connecting line 7 to the connection device of the measuring electrode, in the exemplary embodiment of the single-rod measuring chain. The connecting line 7 extends from the rear region of the tubular body 1 in the longitudinal direction through the inner tube 3 to a longitudinal overlap with the line section 6. In the overlap, the line section 6 and the connecting line 7 are connected in a frictional connection in an electrically conductive and mechanically sufficiently strong manner. The frictional connection is created by means of a hollow shrink body 8, expediently a plastic shrink tube. The shrink body 8 surrounds the line section 6 and the connecting line 8 in the area of ​​the overlap and, in the shrunken state, presses the line section 6 and the connecting line 8 against one another lengthwise.It is advantageous if the shrink body 8 extends a little way beyond the overlap to the rear, as in the exemplary embodiment, only surrounding the connecting cable 7.

[0025] The line section 6 protrudes only a comparatively small length into the cavity H l in. L6 denotes the length by which the line piece 6 projects from the sensor material body 5, i.e. it is the length L6 measured from the free end of the line piece 6 to the back of the sensor material body 5. The length L6 is several times smaller than a length L1 of the tubular body 1. The length L1 is measured from the rear end of the tubular body 1, here from the rear end of the inner tube 3, to the sensor material body 5. The length L1 is advantageously more than five times or more than ten times greater than the length L6. It is advantageous for the contact and tensile strength of the frictional connection if the length L6 is at least 4 mm or at least 6 mm.

[0026] On the other hand, a short length facilitates insertion into the pipe body 1 during joining, so that a length L6 of less than 40 mm or, more preferably, less than 30 mm is advantageous.

[0027] In Fig. Figure 3 shows the sensor assembly consisting of sensor material body 5 and lead piece 6 in the assembled state in a central longitudinal section. The sensor material body 5 is cup-shaped and convex when viewed from its front side. The sensor material body 5 can, for example, be a spherical or hollow spherical cap. The lead piece 6 protrudes from the concave rear side orthogonally to the rear side. Figuratively speaking, the sensor assembly 5, 6 has the shape of a thumbtack or umbrella.

[0028] In Fig. 3 also denotes the length L6 by which the line section 6 protrudes from the rear of the sensor material body 5. D5 denotes the greatest width of the sensor material body 5, ie, the greatest extension of the sensor material body 5 transverse to the longitudinal axis L. In expedient embodiments, the length L6 is less than six times or less than three times the width D3.

[0029] The line piece 6 is electrically and mechanically firmly connected to the sensor material body 5 in a first line section 6a by means of a material bond S2. The line piece 6 protrudes freely from the sensor material body 5 with a second line section 6b. A short transition section connects the line sections 6a and 6b, which point at an angle to each other (in the exemplary embodiment, at an acute angle).

[0030] The lead piece 6 is also made of a precious metal or a precious metal alloy. Advantageously, this is at least substantially the same material as the sensor material body 5. The material bond S2 is a welded connection directly between the sensor material body 5 and the lead piece 6. If the sensor material body 5 and the lead piece 6 are not made of identical materials, in advantageous embodiments the materials are at least similar enough that they can be welded directly, i.e., without weld metal.

[0031] The Fig. 4 to 13 illustrate steps of a method for manufacturing the measuring electrode, wherein the order of the figures corresponds to the sequence of the method.

[0032] In steps not shown, which precede the respective measuring electrode, sensor material bodies 5 and conductor pieces 6 are obtained. A conductor wire is unwound from a wire reel and cut to the length of the respective conductor piece 6. The sensor material body 5 is obtained by separating and forming a strip material. For this purpose, a punching tool can also be designed as a deep-drawing die, so that the sensor material bodies 5 are punched directly from the strip material during the deep-drawing process.

[0033] As in Fig. 4, the sensor material body 5 is moved by a first gripper 11 to a joining receptacle 10 and placed against the joining receptacle 10, for example, placed in the joining receptacle 10. The first gripper 11 is a suction gripper that holds the sensor material body 5 at its rear side using suction force during handling. For this purpose, a vacuum line 17 opens into one end of the first gripper 11. The gripper 11 picks up the respective sensor material body 5 at its rear side with this gripper end. The front side of the sensor material body 5 remains free, so that the sensor material body 5 can very easily be placed with its front side against the joining receptacle 10. The sensor material body 5 is also held on the joining receptacle 10 using suction force. A vacuum line 18 therefore opens into a contact surface provided for the sensor material body 5, via which the sensor material body 5 is sucked in and thereby fixed to the joining receptacle 10.The contact surface is shaped complementarily to the front surface of the sensor material body 5.

[0034] Fig. 5 shows the joining receptacle 10 with the received sensor material body 5, which is subjected to negative pressure via the vacuum line 18 and thereby fixed to the joining receptacle 10. A second gripper 12 holds a line section 6 in a clamping engagement and positions the line section 6 longitudinally on the rear side of the sensor material body 5 fixed to the joining receptacle 10.

[0035] In Fig. 6, the line section 6 is in the joining position on the sensor material body 5. The gripper 12 holds the line section 6 in the joining position. For joining, a joining tool 20, in the exemplary embodiment a welding tool, is pressed against the line section 6 in the joining position in the region of the first line section 6a. In pressure contact, the line section 6 is directly connected to the sensor material body 5 by means of the joining tool 20, in the exemplary embodiment by direct welding, for example, resistance welding.

[0036] To install the sensor assembly 5, 6 in the Fig. 3, the line piece 6, which is positioned on the back of the sensor material body 5 and has already been joined by a material bond, is raised relative to the sensor material body 5 by forming, such as bending or edging. This is expediently carried out by means of the second gripper 12, which remains in clamping engagement with the line piece during the joining and forming process. During the forming process, the line piece 6 in the first line section 6b is pressed against the sensor material body 5 and thereby held down. The joining tool 20 can serve as a hold-down device during the forming process.

[0037] Fig. 7 shows the sensor assembly 5, 6 still in the joining receptacle after the material bond S2 between the sensor material body 5 and the line piece 6 has been established and immediately after the line piece 6 has been erected.

[0038] The forming and material-to-material joining process can also be designed in such a way that the line section 6 is first erected using the gripper 12 and then joined to the sensor material body 5 using the joining tool 20. The joining tool 20 would initially act only as a hold-down device. In another alternative process, the erection can be performed simultaneously with the material-to-material joining.

[0039] During the joining of the sensor material body 5 and the line piece 6 and during the forming of the line piece 6, the sensor material body 5 remains on or in the joining receptacle 10 and can be fixed thereto by means of suction force.

[0040] The sensor assembly 5, 6 obtained by forming and joining can be set aside or even temporarily stored. It is preferably held by a gripper on the line section 6 and transferred to a third gripper for joining with a pipe body 1. The transfer can expediently be performed by the second gripper 12, which can maintain the clamping engagement with the line section 6 and remove the sensor assembly 5, 6 directly from the joining receptacle 10 and transfer it to the third gripper.

[0041] The handover is in Fig. 8. The third gripper 13 is a suction gripper that holds the sensor assembly 5, 6 at the front of the sensor material body 5 by means of suction force. The gripper 13 is therefore connected to a device for generating a vacuum via a vacuum line 19, which opens at a contact surface of the gripper 13. Once the sensor assembly 5, 6 has been picked up by the third gripper 13 by means of the vacuum application, the second gripper 12 releases the clamping engagement with the line section 6, so that the transfer to the gripper 13 is completed. The gripper 13 now holds the sensor assembly 5, 6 at the front of the sensor material body 5, and the line section 6 protrudes freely from the rear of the sensor material body 5.

[0042] To join the sensor assembly 5, 6 with a tubular body 1, the tubular body 1 in question is removed from a separating magazine for tubular bodies 1, moved into a joining position and held in the joining position.

[0043] The Fig. 9 and Fig. 10 shows the joining of the sensor assembly 5, 6 to a tubular body 1, which is clamped in a horizontal orientation in a chuck 15, in the exemplary embodiment a rotary spindle chuck. The tubular body 1 has a front opening 1a at its front end, relative to which the sensor assembly 5, 6 is positioned by means of the gripper 13 such that the rear side of the sensor material body 5 is axially opposite the opening 1a and the line piece 6 protrudes into the tubular body 1, in the exemplary embodiment into its inner cavity H1. Fig. 9, the sensor assembly 5, 6 and the tubular body 1 assume this relative position. A melting device 22, in this embodiment a burner, is used for joining.

[0044] With the pipe body 1 clamped, a measurement is taken to determine the exact position of the front opening 1a. The chuck 15 can then be rotated. The melting device 22 moves from a starting position to a joining position according to the measurement of the position of the opening 1a. Before the actual joining, for example, in the Fig. In the relative position shown in Figure 9, the tubular body 1 is heated by the melting device 22 along its peripheral edge surrounding the opening 1a. The peripheral edge begins to melt, and the opening 1a narrows. The suction gripper 13 moves the sensor assembly 5, 6 in the longitudinal direction L until it touches the already softened peripheral edge of the opening 1a.

[0045] If the pipe body 1 in the cavity H iWhen joining, a negative pressure is applied so that the sensor assembly 5, 6 adheres to the peripheral edge of the opening 1a, the tube body 1 or only the cavity H l at its rear end with a seal. Sealing is preferably performed before the tubular body 1 is set in rotation. Sealing is also advantageous for quality control after joining. After joining, the tubular body 1 can be pressurized while still in the chuck 15, or optionally at another location, to test the fused joint S1 for leaks.

[0046] Fig. 10 shows the joining arrangement of tubular body 1 and sensor assembly 5, 6 with the sensor material body 5 already attached to the tubular body 1. For melting and joining, it is advantageous if the tubular body 1 rotates about its longitudinal axis L. The gripper 13 can be rotatably mounted and remain on the sensor material body during rotation of the tubular body 1. However, it is more expedient if the gripper 13 detaches from the sensor material body 5 immediately before the onset of rotation, so that the sensor assembly 5, 6 can rotate freely from the gripper 13 together with the tubular body 1. In this case, it is advantageous if the sensor group 5, 6 is held to the tubular body 1 by applying negative pressure to the tubular body 1. The rotation centers the sensor assembly 5, 6 on the tubular body 1. Once the fused connection S1 has been established, the melting device 22 moves back to its starting position.

[0047] After joining, overpressure can be generated and monitored to check the fused joint S1 in the pipe body 1. If a pressure drop is detected, the assembly comprising the pipe body 1 and the joined sensor assembly 5, 6 is rejected as defective. If a pressure drop is not detected, the assembly 1, 5, 6 is advanced to the next process step. For this purpose, the rotation of the chuck 15 is stopped if the chuck 15 was previously rotating, the chuck 15 is opened, and a gripper pulls the assembly 1, 5, 6 out of the chuck 15 and places it on a transport device, for example a conveyor belt. The transport device moves the assembly 1, 5, 6 one position further to create a free space for the next assembly 1, 5, 6.The machine cycle begins again and continues until either the transport means is filled, a supply magazine for pipe bodies 1 is emptied or the wire reel for producing line pieces 6 or the strip material for producing sensor material bodies 6 is used up.

[0048] In a subsequent process step, the line section 6 of the respective assembly consisting of the tubular body 1 and the sensor assembly 5, 6 is electrically connected to the connecting line 7 ( Fig. 1 and Fig. 2) connected.

[0049] Fig. 11 shows an assembly 1, 5, 6 in a joining position for establishing the frictional connection. A chuck or gripper 16 holds the assembly 1, 5, 6 in the joining position. The connecting cable 7 and a shrink body 8, expediently a shrink tube, are inserted into the tubular body 1 through the open rear end of the tubular body 1 and advanced in the longitudinal direction L toward the sensor assembly 5, 6 until the connecting cable 7 and the shrink body 8 overlap the cable section 6 lengthwise and the shrink body 8 surrounds the cable section 6 and the connecting cable 7. This positioning of the connecting cable 7 and the shrink body 8 is carried out using an auxiliary tool 23.

[0050] The Fig. 12 next to the shrink body 8 is designed as a tube, for example a glass tube. The shrink body 8 is received in a front receiving section 24 of the auxiliary tool 23 when inserted into the tubular body 1, i.e. the shrink body 8 is shaped so as to be adapted with regard to its outer circumference and the auxiliary tool 3 is shaped so as to be adapted with regard to its inner circumference, at least in the receiving section 24, so that it can receive and hold the shrink body 8 with a slight frictional connection. It is advantageous if the shrink body 8 protrudes beyond the front end of the auxiliary tool 23 when received. In order to receive the shrink body 8 in a defined manner, for example to prevent it from slipping into the hollow auxiliary tool 23, an axial stop 25 for the shrink body 8 is formed in the front end section of the auxiliary tool 23.In the exemplary embodiment, the auxiliary tool 23 is narrowed in the front end section, so that the receiving section 24 for the shrink body 8 and the axial stop 25 are formed there. The connecting line 7 expediently extends through the auxiliary tool 23 and the shrink body 8 when inserted into the tubular body 1.

[0051] In Fig. 13, the auxiliary tool 23, together with the connecting cable 7 and the shrink body 8, is inserted into the joining position of the pipe body 1. It can be seen that the auxiliary tool 3 is adapted in terms of its outer diameter to the inner diameter of the inner pipe 3 of the pipe body 1, so that it is guided axially by the inner pipe 3 during insertion.

[0052] The entire assembly comprising assemblies 1, 5, 6, the connecting cable 7 located in a longitudinal overlap, the shrink body 8 located in a longitudinal overlap, and the inserted auxiliary tool 23 is placed in an oven, expediently together with other such assemblies. In the oven, the assembly or multiple assemblies are heated so that the respective shrink body 8 shrinks and presses the connecting cable 7 in the overlap along the length of the cable section 8, thereby establishing the contact.

[0053] In subsequent process steps, the reference electrode is manufactured, the connecting line 7 and a connecting line of the reference electrode are connected to a connecting device at the rear end of the tubular body 1, and the tubular body 1 is closed by means of the connecting device. Reference symbol: 1 pipe body 1a front opening 2 outer tube 3 inner tube 4 Diaphragm 5 Sensor material body 6 line section 6a first line section 6b second line section 7 Connection cable 8 shrink bodies, shrink tubing 9 - 10 joining holder, receiving tray 11 first gripper 12 second gripper 13 third gripper 14 - 15 chucks 16 chucks 17 Vacuum line 18 Vacuum line 19 Vacuum line 20 joining tools, welding tools 21 - 22 Melting device, burner 23 Auxiliary tools 24 Recording section 25 Axial stop, constriction D5 largest width, diameter of the sensor material body 5 H A outer cavity H l inner cavity L Longitudinal axis, longitudinal direction L1 Length of the pipe body 1 L6 Length of the cable section 6 S1 Fusible link S2 material bond

Claims

[1] Fully automated process for producing a measuring electrode for electrochemical measurements in a measuring fluid, wherein the following steps are carried out in the process: (a) a first gripper (11) places a sensor material body (5) into a joining receptacle (10), (b) the sensor material body (5) is fixed to the joining receptacle (10) by means of suction force, (c) a second gripper (12) positions a piece of line (6) made of electrically conductive material relative to, preferably on, the fixed sensor material body (5), (d) the positioned line piece (6) is materially connected to the fixed sensor material body (5) by means of a joining tool (20) in order to obtain a sensor assembly (5, 6), (e) a tubular body (1) having an end-face opening (1a) in a front tubular body region is held by means of a chuck (15), (f) the sensor assembly (5, 6) and / or the tubular body (1) is / are positioned such that the sensor material body (5) faces the opening (1a) and the line piece (6) projects through the opening (1a) into the tubular body (1), (g) the tubular body (1) is connected in the region of the opening (1a) by means of a melt connection (S1) and / or material bond with the sensor material body (5) in a fluid-tight manner around the opening (1a), (h) a connecting cable (7) made of electrically conductive material and a shrink body (8) are inserted into a tubular auxiliary tool (23), (i) the auxiliary tool (23) with the connecting cable (7) and the shrink body (8) are inserted into the pipe body (1) which is open at a rear end and moved in the direction of the cable section (6), thereby bringing the connecting cable (7) and the shrink body (8) into overlap with the cable section (6), (j) wherein the auxiliary tool (23) surrounds the connecting cable (7) and the shrink body (8), preferably shrink tubing, and (k) the shrink body (8) is shrunk in the overlap by heating, so that the shrunken shrink body (8) presses the cable piece (6) and the connecting cable (7) together lengthwise and thereby connects it in an electrically conductive manner. [2] Method according to the preceding claim, wherein the sensor assembly (5, 6) has the shape of a screen or short nail and the sensor material body (5) forms a cap, for example a spherical shell cap, and the line piece (6) forms a short stem. [3] Method according to one of claims 1 and 2, wherein the first gripper (11) holds the sensor material body (5) by means of suction force on a rear side of the sensor material body (5) and places it against the joining receptacle (10) with a front side of the sensor material body (5). [4] Method according to one of claims 1 to 3, wherein the second gripper (12) is a clamping gripper and holds the line piece (6) in a clamping engagement during positioning in step (c). [5] Method according to one of claims 1 to 4, in which the line piece (6) is erected during or after the material connection to the sensor material body (5) and before the production of the fusion connection (S1) of the tube body (1) and the sensor material body (5) relative to the sensor material body (5) in a direction pointing away from the sensor material body (5), preferably by bending the line piece (6). [6] Method according to the preceding claim, in which the joining tool (20) presses the line piece (6) against the sensor material body (5) when erecting it and thereby holds it down. [7] Method according to one of claims 5 and 6, wherein the line section (6) is erected by means of the second gripper (12). [8] Method according to one of claims 1 to 7, wherein the line piece (6) is welded directly to the sensor material body (5) in step (d) by means of the joining tool (20), for example by resistance welding. [9] Method according to one of claims 1 to 8, in which the sensor assembly (5, 6) is moved into a joining position with a third gripper (13) for producing the fusion connection (S1) of the pipe body (1) and the sensor material body (5), wherein the third gripper (13) is preferably a suction gripper and holds the sensor assembly (5, 6) with suction force, preferably on a front side of the sensor material body (5) facing away from the line piece (6). [10] Method according to one of claims 1 to 9, in which the tubular body (1) is heated at a peripheral edge extending around the front opening (1a) by means of a melting device (22), the sensor material body (5) is placed with its rear side on the peripheral edge and the melt connection (S1) of the sensor material body (5) and the line piece (6) is produced. [11] Method according to one of claims 1 to 10, wherein the sensor material body (5) is obtained from a strip of an electrically conductive material, preferably precious metal, by means of cutting, preferably punching, and forming, preferably deep drawing or deep forming. [12] Method according to the preceding claim, wherein the sensor material body (5) is punched from the strip material during forming. [13] Method according to one of claims 1 to 12, wherein the sensor material body (5) is obtained from a strip of an electrically conductive material in line (in time) of the method by cutting and forming. [14] Method according to one of claims 1 to 13, in which the line piece (6) is cut to length in line with the method from a wire made of an electrically conductive material, preferably precious metal.

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