Method for connecting a thermoplastic line element to a connecting element
Patent Information
- Application Number
- PCT/AT2026/060105
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-04-14
- Filing Date
- 2026-04-09
- Publication Date
- 2026-10-22
Smart Images
Figure AT2026060105_22102026_PF_FP_ABST
Abstract
Description
[0001] METHOD FOR CONNECTING A THERMOPLASTIC CONDUCTING ELEMENT TO A CONNECTING ELEMENT
[0002] The invention relates to a method for producing a welded connection of a conductor element with a connecting element, and to a welding device for carrying out the method.
[0003] The joining of thermoplastic pipe components using a thermoplastic connector equipped with a heating element is a well-known practice. Pipe components in this context refer to pipe sections, fittings, and components that are joined together by the connectors to form pipes and pipe networks. These connectors are frequently designed as electrofusion couplings and electrofusion-weldable connection and tapping clamps. While connectors can also be used to join elements other than pipe components, such as joining rod sections, their use in pipeline construction remains one of the most common applications. In particular, it is also conceivable that the connector is designed as a socket located on one side of a pipe component.
[0004] To ensure the reliable connection of pipe components using such connectors, weld inspection is desirable. EP0173174A1 assumes that the weld quality depends essentially on the correct temperature in the welding area and the welding pressure generated during the welding process, i.e., the pressure exerted on the material in the weld zone that has been plasticized by the applied heat. This pressure arises because the connector has a shrinkage allowance, which manifests itself as a shrinkage of the connector when the weld area is plasticized by the applied heat. This shrinkage, combined with the increase in the material's volume when the weld area is heated, causes this pressure increase in the weld zone.
[0005] Since all circumstances that prevent the achievement of the correct welding temperature and pressure result in a reduction in the quality of the weld, several prior art documents already address welding processes of this type. These include, for example, JP 2000-035178A, JP 2018-156740 A, JP H09-264483 A, US4602148A, US4631107A, US4642155A, US4684789A, and EP3840941B1.
[0006] Electrofusion couplings known from the prior art have the disadvantage that if pipes are not inserted properly into the coupling, a sufficient connection between the pipe and the coupling cannot be established. This leads to leaks in the pipe connections. Furthermore, a pipe that is not inserted properly into the coupling can cause it to overheat locally, which in the worst case can even lead to a fire.
[0007] The object of the present invention was to overcome the disadvantages of the prior art and to provide an improved method and an improved welding device for welding connecting elements.
[0008] This problem is solved by a method and a device according to the claims.
[0009] According to the invention, a method for connecting a thermoplastic conductor element to a connecting element is provided. The method comprises the following steps: providing the at least one thermoplastic conductor element; providing the connecting element, wherein the connecting element has a thermoplastic body and a heating element is embedded in the body, the heating element being located in a welding area to generate heat for welding the body to the at least one conductor element; joining the connecting element to the at least one thermoplastic conductor element; providing a welding device for welding the connecting element to the at least one thermoplastic conductor element; and inputting information about the connecting element to be welded into the welding device.Welding the connecting element to the at least one thermoplastic conductor element by energizing the heating element using the welding device and thus generating heat in the welding area, wherein the welding device stops the welding of the connecting element to the at least one thermoplastic conductor element before the end of the planned welding time and / or the welding device issues an error message when an error criterion is reached, wherein the error criterion is reached when a certain number of error messages are summed in a fault counter implemented in the welding device, wherein a conductor resistance of the heating element is detected during the welding of the connecting element. An error message is added to the fault counter if a resistance drop of the conductor resistance is greater than a resistance change tolerance of the conductor resistance.
[0010] In particular, it can be provided that the conductor resistance is calculated from the current and voltage using Ohm's law. The voltage can be set to a fixed value in the welding machine, and the current can be measured by the welding machine.
[0011] The method according to the invention has the advantage that by stopping the welding process before the end of the planned welding time upon reaching a fault criterion, local overheating of the connecting element and thus a critical situation, such as a fire in the connecting element, can be prevented. Thus, the measures according to the invention surprisingly increase the safety when connecting conductor elements to the connecting element. The method according to the invention enables a safe and efficient connection of thermoplastic conductor elements to a connecting element, whereby the quality of the weld is ensured by monitoring the conductor resistance and adjusting the welding parameters accordingly.
[0012] Furthermore, it can be provided that several of the heating elements are embedded in the body.
[0013] Furthermore, it may be stipulated that the resistance change tolerance is defined or adjusted taking into account the measured conductor resistance. By adjusting the resistance change tolerance to the measured conductor resistance, the reliability of the process can be increased and the welding process further optimized.
[0014] According to further training, it is possible to define the resistance change tolerance as a percentage of the measured conductor resistance. Defining the resistance change tolerance as a percentage of the measured conductor resistance allows for precise adjustment of the tolerance to the current conditions and improves process reliability.
[0015] Furthermore, it may be advantageous to define the resistance change tolerance between 0.1% and 10%, particularly between 0.5% and 5%, preferably between 1% and 3%, of the maximum value of the measured conductor resistance during an observation period. This definition of tolerance limits contributes to further improving process reliability and prevents unnecessary fault messages.
[0016] Alternatively, the resistance change tolerance can be set between 0.1% and 10%, particularly between 0.5% and 5%, preferably between 1% and 3%, of the mean value of the measured conductor resistance over an observation period. This definition of the tolerance limits contributes to further improving process reliability and prevents unnecessary fault messages. Using a mean value has the advantage that any measurement errors or other measurement spikes, which might be caused by measurement errors, for example, do not distort the resistance change tolerance.
[0017] Furthermore, the system can be configured to continuously measure the conductor resistance, with a fault message being added to the fault counter if a drop in conductor resistance within a specific period exceeds the resistance change tolerance. Continuous measurement of the conductor resistance enables ongoing monitoring of the process, further increasing reliability and efficiency.
[0018] In particular, it may be provided that the waste period is defined as a time between 10 milliseconds and 1 second, in particular between 50 milliseconds and 500 milliseconds, preferably between 100 milliseconds and 200 milliseconds.
[0019] Furthermore, it can be stipulated that the resistance drop is calculated from a maximum or average value of the measured conductor resistance over an observation period. This calculation method ensures that the resistance change is precisely recorded and evaluated, thus increasing the reliability of the procedure.
[0020] It is also advantageous to have a configuration in which the observation period begins between 1.1 and 10 sees in the past from the respective measurement time, particularly between 1.2 and 5 sees, preferably between 2 and 4 sees, and the observation period ends between 0 and 1 sees in the past from the respective measurement time, particularly between 0.01 and 0.8 sees, preferably between 0.1 and 0.3 sees. The choice of observation period allows for optimal adaptation to the specific requirements and improves the accuracy of resistance monitoring.
[0021] Furthermore, it can be advantageous to calculate the ratio between the length of the fall-off period and the resistance change tolerance. This relationship enables precise and tailored monitoring of the resistance drop, which further increases process reliability.
[0022] Furthermore, it can be provided that X fault messages are added to the fault counter if the resistance drop of the conductor is X times the resistance change tolerance, in particular that only integer fault messages are added to the fault counter. This measure ensures that only significant resistance drops are recorded as faults, which increases the reliability of the method. This measure also ensures that multiple fault messages are added if the resistance drop of the conductor is several times the resistance change tolerance.
[0023] Furthermore, it can be stipulated that the fault criterion is reached when the fault counter reaches a number of 3 to 10 fault messages, in particular 4 to 8 fault messages, preferably 5 to 7 fault messages. This definition of the fault criterion ensures that the process is only interrupted in the event of significant faults, thus increasing efficiency and reliability.
[0024] Furthermore, it can be implemented that a fault message is subtracted from the fault counter if the increase in conductor resistance within a specific rise period exceeds the resistance change tolerance of the conductor resistance. This measure also takes positive resistance changes into account and prevents unnecessary fault messages, thus further increasing process reliability.
[0025] In particular, it may be provided that the rise time is defined as a time between 10 milliseconds and 1 second, in particular between 50 milliseconds and 500 milliseconds, preferably between 100 milliseconds and 200 milliseconds.
[0026] Furthermore, it can be stipulated that the fall-off period and the rise-off period are of equal length. Additionally, it can be stipulated that a welding voltage is raised to a specific value when the welding machine is activated for welding and subsequently maintained within a welding voltage tolerance of this value. Precise adjustment of the welding voltage ensures that the welding takes place under optimal conditions, which increases the quality and reliability of the joint.
[0027] In particular, it can be provided that the welding voltage is increased to a value between 20V and 55V, especially between 25V and 48V, preferably between 37.5V and 42.5V. This has the advantage that a good weld of the connecting element can be achieved at a welding voltage in this range.
[0028] Furthermore, it can be provided that the welding stress tolerance is between 0% and 20%, in particular between 0.1% and 10%, preferably between 1% and 3%, of the welding stress value. This offers the advantage of a stable weld of the connecting element.
[0029] The invention also provides a welding device for welding a thermoplastic conductor element to a connector element. The welding device comprises a control unit and an input interface for entering information about the connector element to be welded, the input interface being coupled to the control unit. The control unit is configured to execute the method according to one of the preceding claims. The welding device according to the invention has the advantage that by stopping the welding process before the end of the planned welding time upon reaching a fault criterion, local overheating of the connector element and thus a critical situation, such as a fire in a connector element, can be prevented. Thus, the measures according to the invention surprisingly increase safety when connecting conductor elements to the connector element.The welding device according to the invention enables a safe and efficient connection of thermoplastic conductor elements with a connecting element, whereby the quality of the weld is ensured by monitoring the conductor resistance and adjusting the welding parameters accordingly.
[0030] To better understand the invention, it is explained in more detail with reference to the following figures. These show, in a highly simplified, schematic representation:
[0031] Fig. 1 shows a sectional view of an embodiment of a connecting element of a welding arrangement;
[0032] Fig. 2 a) a schematic representation of the time course of the current and voltage during the welding process of a correctly performed weld;
[0033] Fig. 2 b) a schematic representation of the time course of the internal resistance of the resistance heating wire during the welding process of a correctly performed weld;
[0034] Fig. 3 a) a schematic representation of the time course of the current and voltage during the welding process of an incorrectly performed weld;
[0035] Fig. 3 b) a schematic representation of the time course of the internal resistance of the resistance heating wire during the welding process of an incorrectly performed weld;
[0036] Fig. 4 shows a detailed view of a first embodiment of a weld with achievement of a shutdown criterion;
[0037] Fig. 5 shows a detailed view of a second embodiment of a weld with achievement of a shutdown criterion.
[0038] It should be noted at the outset that in the differently described embodiments, identical parts are provided with the same reference numerals or component designations, and the disclosures contained in the entire description can be applied analogously to identical parts with the same reference numerals or component designations. Furthermore, the orientation designations chosen in the description, such as top, bottom, side, etc., refer to the figure directly described and illustrated, and these orientation designations must be applied analogously to the new position if the orientation changes.
[0039] Fig. 1 shows a first embodiment of a welding arrangement 1 with a connecting element 2 for connecting conductor elements 3. In the embodiment according to Fig. 1, the connecting element 2 is designed in the form of an electrofusion sleeve and the conductor elements 3 are designed in the form of pipes.
[0040] As can be seen from Fig. 1, the connecting element 2 can be provided with a thermoplastic body 4 in which a heating element 6 is arranged in a welded area 5. The heating element 6 can in particular be in the form of a resistance heating wire 7.
[0041] For example, it is conceivable that the connecting element 2 serves to connect two conductor elements 3 and thus two welding areas 5 are formed in the body 4 of the connecting element 2.
[0042] One of the welding areas 5 serves to weld the connecting element 2 to the first conductor element 3, and a second of the welding areas 5 serves to weld the connecting element 2 to the second conductor element 3.
[0043] As can be further seen from Fig. 1, the heating element 6 can be provided with a first connection point 8 and a second connection point 9, each of which serves for connection to a welding machine 10. The two connection points 8, 9 can be, as shown in Fig.
[0044] As shown in Figure 1, the welding area 5 is formed in the region of the two longitudinal ends of the connecting element 2, whereby both welding areas 5 can be heated simultaneously by means of the welding device 10. The welding areas 5 can be heated, in particular, by applying an electric current and an electric voltage to the first connection point 8 and the second connection point 9 of the heating element 6 by means of the welding device 10. This, along with the conductor resistance of the heating element 6, causes the heating element 6 to heat up.
[0045] Furthermore, it is also conceivable that each welding area 5 has a first connection point 8 and a second connection point 9 for the welding device 10. This makes it possible for each of the two welding areas 5 to be heated individually and independently of the other, and for a weld connection to be made separately between the connecting element 2 and the first conductor element 3, as well as between the connecting element 2 and the second conductor element 3. As can also be seen in Fig. 1, a stop 11 can be provided on the body 4 of the connecting element 2, which serves to correctly position the two conductor elements 3 in the connecting element 2. The stop 11 can be located centrally in the connecting element 2.
[0046] As can be further seen from Fig. 1, the welding machine 10 has a control unit 12, which serves to control the welding process or to control the welding machine 10. In particular, the control unit 12 can be provided for storing a computer program. Thus, commands that cause a digital computer of the control unit 12 to execute the process steps according to the invention can be stored on the control unit 12.
[0047] Furthermore, the welding machine 10 has an input interface 13, which is coupled to the control unit 12. The input interface 13 serves to acquire information about the connecting element 2 to be welded and / or about the cable elements 3 to be welded. In the embodiment according to Fig. 1, the input interface 13 is designed as a scanner, which serves to capture a barcode printed on the connecting element 2. In an alternative embodiment, the input interface 13 can also include other acquisition means, such as for capturing an RFID element. In another embodiment, the input interface 13 can also include a keyboard or other input means, or be designed as a touchscreen for input. It is also conceivable that the input interface 13 includes a microphone for voice input.
[0048] Additionally, the welding machine 10 can include a display unit 14, which serves to output information to a machine operator. The display unit 14 can be coupled to a control panel, which is used by the user to operate the welding machine 10.
[0049] Furthermore, it may be provided that a detection device 15 is designed which is coupled to the welding device 10.
[0050] The detection device 15 can, for example, serve to detect the correct insertion of the conductor elements 3 into the connecting element 2. In particular, the detection device 15 can be designed as an optical detection device for this purpose. It is also conceivable that the detection device 15 is designed as a sensor, for example as a Hall sensor, an ultrasonic sensor, an X-ray sensor, or another type of sensor, to detect the position of the conductor elements 3 in the connecting element 2. In particular, it can be provided that a transmitter 16 is arranged on the conductor element 3 itself, which interacts with the detection device 15. The transmitter 16 can, for example, be an RFID tag. Furthermore, it is also conceivable that the transmitter 16 is another element, such as a piece of wire, which can be addressed via induction or by means of the Hall sensor.
[0051] In another embodiment, the detection device 15 can also be a sensor used to monitor the welding process itself. For example, the detection device 15 can be designed as a thermal imaging camera capable of detecting local overheating. In particular, it can be provided that the detection device 15 acquires information that is taken into account in the welding process.
[0052] Of course, it is also conceivable that two different detection means 15 are used to detect that the conductor elements 3 are correctly inserted into the connecting element 2 and to monitor the welding process itself, as described in the two paragraphs above.
[0053] Furthermore, a fault counter 17 can be implemented in the control unit 12, which serves to record faults during the welding process. The fault counter 17 can be implemented in the programming of the control unit 12. In other words, the fault counter 17 can be implemented in the software of the control unit 12.
[0054] The welding process for joining the thermoplastic conductor element 3 with the connecting element 2 is subsequently described with reference to Fig. 1.
[0055] To weld the connecting element 2 to the conductor elements 3, the conductor elements 3 are inserted into the connecting element 2. This insertion can also be referred to as joining.
[0056] Furthermore, information about the properties of the connecting element 2 can be entered into the welding machine 10. This information can be entered, for example, by scanning a barcode located on the connecting element 2 using an input interface 13 designed as a barcode scanner. Based on this information, the parameters for carrying out the welding process can be defined. This will be discussed in more detail below.
[0057] Furthermore, the first connection point 8 and the second connection point 9 of the connecting element 2 can be connected to the welding device 10, thus enabling the welding of the connecting element 2 to the conductor element 3.
[0058] During the welding process itself, the first connection point 8 and the second connection point 9 are supplied with current or voltage, causing the resistance heating wire 7 to heat up and melt the connecting element 2 in the welding area 5. If the conductor elements 3 are correctly inserted into the connecting element 2, the connecting element 2 can fuse with the conductor element 3, thereby achieving a sufficiently tight connection between the conductor elements 3 and the connecting element 2.
[0059] If, as shown in Fig. 1 on the right-hand conductor element 3, the conductor element 3 is not correctly inserted into the connecting element 2, this can lead to the section of the weld area 5 of the connecting element 2, where the conductor element 3 is not in contact, melting uncontrollably due to the lack of heat dissipation. This can result in uncontrolled leakage of material from the connecting element 2 in this area.
[0060] Furthermore, due to this material escaping from the connecting element 2, it can happen that two windings of the resistance heating wire 7 contact each other due to the resulting displacements, thereby short-circuiting and bridging the winding loop of these two adjacent windings of the resistance heating wire 7. Surprisingly, the inventive method allows this effect to be used to detect, by means of the welding machine 10, whether the welding is being carried out correctly and, if necessary, to stop the welding process and / or issue an error message from the welding machine.
[0061] Figure 2a shows, in one embodiment, the time course of the welding current 19 and the welding voltage 20 during the welding of the connecting element 2. In the embodiment shown in Figure 2a, the welding process is regular and without defects. The elapsed time in seconds is shown on the abscissa. The magnitude of the welding current 19 is shown in amperes on the ordinate. The magnitude of the welding voltage 20 is shown in volts on the ordinate.
[0062] As can be seen in Fig. 2a, it can be provided that the welding voltage 20 is increased to a specific value when the welding machine 10 is activated for welding and then kept constant at this value. Due to technical or external influences, it is conceivable that the welding voltage 20 fluctuates slightly, but is maintained within a welding voltage tolerance 21 of this value. The welding voltage tolerance 21 is the upper or lower deviation from the welding voltage 20.
[0063] The welding current 19 can decrease over the course of the welding process because the heating of the resistance heating wire 7 increases the conductor resistance 23 of the resistance heating wire 7.
[0064] The course of the welding current 19 as shown in Fig. 2a is the course that occurs in a correctly welded connecting element 2.
[0065] The currently available welding current 19 can be queried in a query interval 22, whereby a measurement of the welding current 19 is carried out at the interval of the query interval 22.
[0066] Fig. 2b shows the time course of the conductor resistance 23 during the welding process. The elapsed time in seconds is shown on the abscissa. The magnitude of the conductor resistance 23 is shown in ohms on the ordinate. As can be seen from Fig. 2b, the conductor resistance 23 increases over time. This increase in the conductor resistance 23 over time is due to physical factors and results from the heating of the resistance heating wire 7.
[0067] The increase in conductor resistance 23 varies for each different design of the connecting element 2, as well as for different welding parameters and different environmental conditions. The conductor resistance 23 can be measured at a query interval 22, whereby a measurement of the conductor resistance 23 can be carried out at intervals of the query interval 22.
[0068] In a first version, the conductor resistance 23 and also the welding current 19 can be determined in the query interval 22.
[0069] In an alternative version, it is also conceivable that either the conductor resistance 23 or the welding current 19 is determined and that the other value is calculated using Ohm's law U=R * I.
[0070] Figure 3a shows the time course of the welding current 19 during a defective weld, using the same reference numerals and element designations for identical elements as in the preceding Figure 2a. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figure.
[0071] 2a was indicated or referenced.
[0072] Figure 3b shows the corresponding curve of the conductor resistance 23 of an incorrectly welded connecting element 2, where the same reference numerals and element designations are used for identical elements as in the preceding Figure 2b. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figure 2b.
[0073] As can be seen from Fig. 3a, if the connecting element 2 is not connected correctly, the welding current 19 can increase if two or more turns of the resistance heating wire 7 come into contact with each other and are thus short-circuited.
[0074] The short circuit of several turns of the resistance heating wire 7 leads to a drop in the conductor resistance 23, as can be seen in Fig. 3b.
[0075] Fig. 4 shows a detailed view of the decreasing conductor resistance 23 from Fig. 3b, where the same reference numerals and element designations are used for identical elements as in the preceding Fig. 3b. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Fig. 3b. With reference to Fig. 4, an exemplary embodiment is used to describe how a fault criterion for stopping the welding process before the end of the planned welding time can be defined.
[0076] In particular, it can be specified that the error criterion is reached when a certain number of fault messages are counted in the fault counter 17. In the present embodiment according to Fig. 4, for example, there are six fault messages. According to this embodiment, it can be defined that the welding process is aborted when the sixth fault message is reached.
[0077] As can be seen in detail in Fig. 4, the conductor resistance 23 can drop abruptly when two turns of the resistance heating wire 7 are short-circuited. This drop in conductor resistance 23 can be detected by the welding machine 10 and cause a fault message to be added to the fault counter 17. The underlying calculation for recording the fault message can be performed as follows.
[0078] Starting from the beginning of the welding process, the conductor resistance 23 can be continuously or periodically recorded within a query interval 22. For calculations in the fault counter 17, an observation period 24 can be defined. The query interval 22 is only shown schematically in the figures and can be much finer or more granular than depicted, compared to the curve of the conductor resistance 23.
[0079] The conductor resistance 23, in particular a maximum value of the conductor resistance 23 or an average value of the conductor resistance 23, within the observation period 24 can be used as a reference for determining a fault message.
[0080] The observation period 24 can lie in the past at the current measurement time 25. In particular, it can be stipulated that the observation period 24 runs from a period start 26 to a period end 27. The observation period 24, especially the period start 26 and the period end 27, can thus be at a constant interval from the respective current measurement time 25. In particular, it can be stipulated that, with respect to the measurement time 25, not only the period start 26 but also the period end 27 lies at a time interval from the measurement time 25 in the past. The measured values of the observation period 24 can be stored in a buffer. Furthermore, it is also conceivable that the measured values of the observation period 24 are continuously overwritten in the buffer as the observation period 24 progresses.
[0081] Furthermore, it may be provided that a resistance change tolerance 28 is defined or set based on the conductor resistance 23 measured during the observation period 24, in particular its maximum value or its mean value. If a resistance drop 29 of the conductor resistance 23 is greater than the determined resistance change tolerance 28, a fault message can be added to the fault counter 17.
[0082] In the event that the resistance drop 29 is an integer multiple of the resistance change tolerance 28, integer multiples of fault messages can be added to the fault counter 17.
[0083] The resistance drop 29 can be a resistance difference between the conductor resistance 23 at the current measurement time 25 and the conductor resistance 23 or its maximum value or its mean value within the observation period 24.
[0084] In particular, it may be provided that the fault counter 17 takes into account whether the resistance drop 29 within a certain drop period 30 is greater than the resistance change tolerance 28 of the conductor resistance 23. The drop period 30 may be calculated from a current measurement time 25 into the past.
[0085] In particular, the decay period 30 can be defined such that only an abrupt drop in resistance 29 triggers a fault message. A slow and steady drop in resistance 29 can be disregarded if necessary.
[0086] In particular, it may be provided that the query interval 22 is chosen in such a way that it has a sufficiently high resolution to be able to capture even a short waste period 30.
[0087] In the case of a first fault event 31, as shown in Fig. 4, the resistance drop 29 is, for example, 1.2 times the resistance change tolerance 28. A value of 1 can therefore be added to the fault counter 17. A second fault event 32 may occur later during the welding process. Due to the calculation method of the resistance change tolerance 28 and the concurrent observation period 24, the resistance change tolerance 28 for the second fault event 32 may be slightly lower than the resistance change tolerance 28 for the first fault event 31.
[0088] During the second fault event 32, the resistance drop 29 at measurement time 25 is 2.6 times the currently relevant resistance change tolerance 28. Therefore, two further fault messages can be added to the fault counter 17. In total, the fault counter 17 can thus display three fault messages at this time.
[0089] Mutatis mutandis to the procedure already described, a further fault message can be added to the fault counter 17 in the event of a third fault event 33.
[0090] Mutatis mutandis to the procedure already described, two further fault messages can be added to the fault counter 17 upon a fourth fault event 34. Thus, upon the fourth fault event 34, the fault counter 17 can, for example, be increased to six fault messages, thereby exceeding the tolerance for permissible fault messages. The welding process can then be aborted.
[0091] For example, if during the third fault event 33 the resistance drop 29 of the conductor resistance 23 were smaller than the determined resistance change tolerance 28, no fault message would be added to the fault counter 17.
[0092] Fig. 5 shows another possible process sequence for a welding operation, where again the same reference numerals or element designations are used for identical elements as in the preceding Fig. 4. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Fig. 4.
[0093] As can be seen in Fig. 5, it is possible that after at least one disturbance event 31, the cause of the disturbance resolves itself. This can occur, for example, when two touching windings of the resistance heating wire 7 separate from each other again. This can lead to a renewed increase in the conductor resistance 23. Specifically, in the second embodiment according to Fig. 5, the following welding process can occur.
[0094] Starting from the start of the welding process, the conductor resistance 23 can be continuously or periodically recorded at a query interval 22. An observation period 24 can be defined for the calculation in the fault counter 17.
[0095] In the case of a first disturbance event 31, as shown in Fig. 5, the resistance drop 29 is, for example, 1.2 times the resistance change tolerance 28. A value of 1 can therefore be added to the disturbance counter 17.
[0096] A second disturbance event 32 may occur later during the welding process. Due to the calculation method of the resistance change tolerance 28 and the concurrent observation period 24, the resistance change tolerance 28 during the second disturbance event 32 may be slightly lower than the resistance change tolerance 28 during the first disturbance event 31.
[0097] For example, during the second fault event 32, the resistance drop 29 at measurement time 25 is 2.6 times the currently relevant resistance change tolerance 28. Therefore, two further fault messages can be added to the fault counter 17. In total, the fault counter 17 can thus display three fault messages at this time.
[0098] Subsequently, a resistance increase 36 of the conductor resistance 23 can occur. This resistance increase 36 of the conductor resistance 23 can be referred to as the first reset event 35. The resistance increase 36 takes place within a rise period 37.
[0099] Furthermore, it may be provided that a resistance change tolerance 28 is defined or set based on the conductor resistance 23 measured during the observation period 24, in particular its maximum value or its mean value. If a resistance increase 36 of the conductor resistance 23 is greater than the determined resistance change tolerance 28, a fault message can be deducted from the fault counter 17.
[0100] In the event that the resistance increase 36 is an integer multiple of the resistance change tolerance 28, integer multiples of fault messages can be subtracted from the fault counter 17. The resistance increase 36 can be a resistance difference between the conductor resistance 23 at the current measurement time 25 and the conductor resistance 23, or its maximum value or its average value within the observation period 24.
[0101] In particular, it may be provided that the fault counter 17 takes into account whether the resistance increase 36 within a certain rise period 37 is greater than the resistance change tolerance 28 of the conductor resistance 23. The rise period 37 may be calculated from a current measurement time 25 into the past.
[0102] Thus, it can be provided that the resistance increase 36 is taken into account mutatis mutandis in the resistance decrease 29 in the fault counter 17, whereby a fault message is subtracted from the fault counter 17.
[0103] At the first reset event 35, the resistance increase 36 at measurement time 25 is, for example, 2.2 times the currently relevant resistance change tolerance 28. Therefore, two fault messages can be subtracted from the fault counter 17. Overall, the fault counter 17 can thus only show one fault message at this time.
[0104] In another embodiment, it can be provided that the resistance increase 36 is not taken into account in the fault counter 17 even if the resistance change tolerance 28 is exceeded. Thus, a reduction in fault messages cannot be provided.
[0105] Each time a welding process is restarted, it can be provided that the fault counter 17 is reset to zero.
[0106] The exemplary embodiments show possible embodiment variants, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiment variants, but rather various combinations of the individual embodiment variants are also possible and this possibility of variation lies within the skill of the person skilled in this technical field due to the teaching on technical action by the present invention.
[0107] The scope of protection is defined by the claims. However, the description and drawings must be consulted for the interpretation of the claims. Individual features or combinations of features from the different embodiments shown and described can, in themselves, constitute independent inventive solutions. The problem underlying these independent inventive solutions can be found in the description.
[0108] All references to value ranges in this description are to be understood as encompassing any and all sub-ranges thereof, e.g., the reference 1 to 10 is to be understood as including all sub-ranges, starting from the lower limit 1 and the upper limit 10, i.e., all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g., 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.
[0109] Finally, for the sake of clarity, it should be noted that, for better understanding of the structure, some elements have been shown not to scale and / or enlarged and / or reduced. Reference symbol list
[0110] Welding arrangement 32 second fault event V connection element 33 third fault event line element 34 fourth fault event body 35 first reset event welding area 36 resistance increase heating element 37 rise period resistance heating wire
[0111] first connection point
[0112] second connection point
[0113] Welding machine
[0114] stop
[0115] control unit
[0116] Input interface
[0117] Display unit
[0118] Recording equipment
[0119] Transmitter
[0120] Fault counter
[0121] Disruption period
[0122] Welding current
[0123] Welding voltage
[0124] S ch white voltage tolerance
[0125] Query interval
[0126] conductor resistance
[0127] B observation period
[0128] Measurement time
[0129] Start of period
[0130] End of period
[0131] Resistance change tolerance
[0132] Resistance drop
[0133] Waste collection period
[0134] first disturbance event
Claims
Patent claims 1. Method for connecting a thermoplastic conductor element (3) to a connecting element (2) comprising the process steps: - Providing at least one thermoplastic conductor element (3); - Providing the connecting element (2), wherein the connecting element (2) has a thermoplastic body (4), wherein a heating element (6) is embedded in the body (4), wherein the heating element (6) serves in a welding area (5) to generate heat for welding the body (4) to the at least one conductor element (3); - Joining the connecting element (2) with the at least one thermoplastic conductor element (3); - Providing a welding device (10) for welding the connecting element (2) to the at least one thermoplastic conductor element (3); - Entering information about the connecting element to be welded (2) into the welding machine (10); - Welding the connecting element (2) to the at least one thermoplastic conducting element (3) by energizing the heating element (6) using the welding device (10) and thus generating heat in the welding area (5), where the welding of the connecting element (2) with the at least one thermoplastic conductor element (3) is stopped by the welding machine (10) before the end of the planned welding time and / or an error message is issued by the welding machine (10) when an error criterion is reached, wherein the fault criterion is reached when a certain number of fault messages are summed in a fault counter (17) implemented in the welding machine (10), wherein a conductor resistance (23) of the heating element (6) is detected during the welding of the connecting element (2), characterized by the fact that 1. A fault message is added to the fault counter (17) if a resistance drop (29) of the conductor resistance (23) is greater than a resistance change tolerance (28) of the conductor resistance (23).
2. Method according to claim 1, characterized in that the resistance change tolerance (28) is determined or adjusted taking into account the measured conductor resistance (23).
3. Method according to claim 2, characterized in that the resistance change tolerance (28) is defined as a percentage value of the measured conductor resistance (23).
4. Method according to claim 3, characterized in that the resistance change tolerance (28) is set between 0.1% and 10%, in particular between 0.5% and 5%, preferably between 1% and 3%, of a maximum value or an average value of the measured conductor resistance (23) of an observation period (24).
5. Method according to one of claims 2 to 4, characterized in that the conductor resistance (23) is continuously measured, wherein a fault message is added to the fault counter (17) if a resistance drop (29) of the conductor resistance (23) within a certain drop time period (30) is greater than the resistance change tolerance (28) of the conductor resistance (23).
6. Method according to claim 5, characterized in that the resistance drop (29) is calculated from a maximum value or an average value of the measured conductor resistance (23) of an observation period (24).
7. Method according to claim 6, characterized in that the start of the observation period (24) from the respective measurement time (25) is between 1.1 and 10 see, in particular between 1.2 and 5 see, preferably between 2 and 4 see in the past, and that the end of the observation period (27) from the respective measurement time (25) is between 0 and 1 see, in particular between 0.01 and 0.8 see, preferably between 0.1 and 0.3 see in the past.
8. Method according to any one of claims 5 to 7, characterized in that the size of the decay period (30) and the resistance change tolerance (28) are calculated in a ratio to each other.
9. Method according to one of the preceding claims, characterized in that X fault messages are added to the fault counter (17) when the resistance drop (29) of the conductor resistance (23) is X times the resistance change tolerance (28), in particular that only integer fault messages are added to the fault counter (17).
10. Method according to one of the preceding claims, characterized in that the error criterion is reached when the fault counter (17) reaches a number of 3 to 10 fault messages, in particular 4 to 8 fault messages, preferably 5 to 7 fault messages.
11. Method according to one of the preceding claims, characterized in that a fault message is subtracted from the fault counter (17) if a resistance increase (36) of the conductor resistance (23) within a certain rise period (37) is greater than the resistance change tolerance (28) of the conductor resistance (23).
12. Method according to one of the preceding claims, characterized in that a welding voltage (20) is increased to a certain value when the welding device (10) is activated for welding and is subsequently maintained within a welding voltage tolerance (21) of this value.
13. Method according to claim 12, characterized in that the welding voltage (20) is increased to a value between 20V and 55V, in particular between 25V and 48V, preferably between 37.5V and 42.5V.
14. Method according to claim 12 or 13, characterized in that the welding stress tolerance (21) is between 0% and 20%, in particular between 0.1% and 10%, preferably between 1% and 3%, of the value of the welding stress (20).
15. Welding device (10) for welding a thermoplastic conductor element (3) to a connecting element (2), wherein the welding device comprises a control unit (12) and an input interface (13) for inputting information about the connecting element (2) to be welded, wherein the input interface (13) is coupled to the control unit (12), characterized in that the control unit (12) is configured to execute the method according to one of the preceding claims.