Device for measuring welding force and detecting welding voltage during welding process of resistance welding equipment

Abstract

The invention relates to a device (1) for measuring welding force and detecting welding voltage during a welding process in a resistance welding apparatus (2) having a welding tongs (20) with two electrode arms (20.1, 20.2); the device has two contact sockets (12, 13) for placing the device (1) on the electrode arms (20.1, 20.2); at least one sensor element (15.1-15.3) for measuring the welding force applied by the electrode arms (20.1, 20.2) during the welding process; and at least one assembly (17.1-17.3) for detecting the welding voltage during the welding process; wherein the device (1) has a coupling (14) which, in the state in which the device (1) is placed on the electrode arms (20.1, 20.2), mechanically couples the device (1) with the resistance welding apparatus (2).

Description

Technical Field

[0001] This invention relates to a device for measuring welding force and detecting welding voltage during the welding process in a resistance welding equipment. Background Technology

[0002] Resistance welding equipment can be used to weld metal workpieces, such as sheet metal. This type of equipment is used in welding robots and is widely applied in the metal processing industry. Typically, resistance welding equipment includes a welding clamp with two electrode arms. At least one electrode arm is configured to be movable, while the other may be fixed in position. The welding clamp can be opened and closed by moving the movable electrode arm. When the clamp is open, the workpiece is positioned between the electrode arms; when the clamp is closed, a welding force of several kN is applied to the workpiece. During the welding process, the magnitude of the welding force, the welding current, and the welding voltage are predetermined. Typically, the welding process begins only when the workpiece is subjected to 90% of the minimum welding force. Then, during the welding process, the workpiece is welded with a welding voltage of several volts (V) and a welding current of several tens of kA.

[0003] To achieve consistently high weld quality during the welding process, a device is needed to measure the welding force and detect the welding voltage applied during welding. These measurements and detections are recorded periodically. This measurement and detection also allows for the determination of the welding clamp's maintenance needs.

[0004] The applicant commercially markets the 9831C welding force calibration transmitter as a device for measuring welding force and detecting welding voltage during the welding process in resistance welding equipment, and describes it in the operating manual 9831C_002.567d-04.11. The device has a handle with two contact sockets. The operator holds the device using the handle, and the device is centered between the electrode arms via the contact sockets, replacing the workpiece.

[0005] The device features a piezoelectric sensor element that generates polarization charges under welding force. The amount of polarization charge is proportional to the magnitude of the welding force. The welding force is measured using these polarization charges. The device also includes a charge amplifier unit that amplifies the polarization charges into a DC voltage.

[0006] The device has components for detecting the welding voltage applied between the electrode arms.

[0007] Currently, the metalworking industry prefers to operate such equipment in the absence of an operator. In particular, for safety reasons, welding robots should not work alongside operators without spatial separation via protective devices.

[0008] Subsequently, during the welding process, when measuring welding force and detecting welding voltage, vibration and bending moments are transmitted into the device through the handle as the operator holds it. These vibration and bending moments can distort the measurement of welding force and the detection of welding voltage during the welding process. Therefore, the remedy is to repeat the measurement and detection multiple times to obtain a statistical average, which reduces the impact of distortion caused by vibration and bending moments on the accuracy of measurement and detection. However, repeatedly measuring welding force and detecting welding voltage during the welding process is both time-consuming and expensive. Summary of the Invention

[0009] The purpose of this invention is to provide a device for measuring welding force and detecting welding voltage during the welding process of a resistance welding equipment. This device can operate autonomously without the operator's presence, allowing for high-precision measurement of welding force and detection of welding voltage during the welding process. Furthermore, this device can perform the measurement of welding force and detection of welding voltage simply, quickly, and inexpensively during the welding process.

[0010] The objective of this invention is achieved through the features of the technical solution of this invention.

[0011] This invention relates to an apparatus for measuring welding force and detecting welding voltage during the welding process in a resistance welding apparatus having a welding clamp with two electrode arms. The apparatus includes: two contact sockets for placing the apparatus on the electrode arms; at least one sensor element for measuring the welding force applied by the electrode arms during welding; and at least one component for detecting the welding voltage during welding; wherein the apparatus has a coupling member that mechanically couples the apparatus to the resistance welding apparatus when it is placed on the electrode arms.

[0012] By mechanically coupling the device to the resistance welding equipment according to the present invention, the operator no longer needs to hold the device for measuring welding force and detecting welding voltage during the welding process. This mechanical coupling can be implemented simply and quickly, and allows the device to operate autonomously. By eliminating the operator's grip, vibration and bending moments are also prevented from being introduced into the device, which improves the accuracy of measuring welding force and detecting welding voltage during the welding process.

[0013] Preferred embodiments of the present invention are given by way of the technical solution according to the present invention.

[0014] In a preferred embodiment, the two electrode arms include a lower electrode arm and an upper electrode arm; wherein the two contact sockets include a lower contact socket and an upper contact socket; wherein the lower contact socket has a lower conical recess that receives the foremost tip of the lower electrode arm and is centered relative to the vertical axis when the device is placed on the electrode arm; and wherein, in order to mechanically couple the device to the resistance welding equipment, the coupling member applies a coupling force on the resistance welding equipment.

[0015] In other words, the coupling element applies a coupling force to the resistance welding equipment for mechanical coupling between the device and the equipment. Applying the coupling force can be done simply and quickly and allows for autonomous operation of the device.

[0016] In a preferred embodiment, the coupling element has a coupling body that is fastened to a lower contact socket on the outside; wherein the coupling body has a coupling opening that extends along a vertical axis through the coupling body and communicates with a lower conical recess; wherein, with the device placed on an electrode arm, the lower electrode arm extends through the coupling opening; and wherein, the coupling element for mechanical coupling of the device and the resistance welding equipment applies a coupling force to the lower electrode arm in the coupling opening.

[0017] Therefore, the device can easily achieve mechanical coupling with the lower electrode arm, since the lower electrode arm will extend through the coupling opening of the coupling member regardless of whether the device is placed on the electrode arm. This mechanical coupling can also be implemented simply and quickly and allows the device to operate autonomously.

[0018] In a preferred embodiment, the coupling member has a clamping element that radially surrounds the coupling opening; wherein the clamping element has a first clamping element end and a second clamping element end that are spaced apart from each other along and through a gap; and wherein a reduction in the gap width applies a coupling force to the lower electrode arm.

[0019] Therefore, the clamping element is a clamping element with two clamping element ends spaced apart from each other by a gap. The clamping element applies coupling force by reducing the gap width, which is simple, fast and allows the device to operate autonomously.

[0020] In a preferred embodiment, the coupling has a tensioning element disposed on a clamping element; wherein the tensioning element has a sleeve element and a screwing element; wherein the sleeve element is fastened to the end of a first clamping element and holds the screwing element; and wherein the screwing element can be screwed into the end of a second clamping element and by such screwing in the gap width is reduced.

[0021] Screwing the screwing element into the end of the second clamping element to reduce the gap width can be done simply and quickly, and allows the device to operate autonomously.

[0022] In another preferred embodiment, a retaining element is arranged in the coupling opening; wherein, with the device placed on the electrode arm, the lower electrode arm extends through the coupling opening and presses against the retaining element; and wherein the pressed retaining element applies a coupling force to the lower electrode arm.

[0023] Arranging a clampable retaining element that applies coupling force to the lower electrode arm in the clamped state within the coupling opening can be done simply and quickly, and allows for autonomous operation of the device.

[0024] In another preferred embodiment, the resistance welding equipment has a support; wherein the device, when placed on the electrode arm, is mechanically coupled to the support; wherein the coupling element is constituted by another fastener; and wherein the other fastener applies a coupling force to the support to mechanically couple the device and the resistance welding equipment.

[0025] This mechanical coupling, consisting of only one fastener, on the support of the resistance welding equipment can be performed simply and quickly, allowing for autonomous operation of the device.

[0026] In another preferred embodiment, the device has a lower housing, an upper housing, and an insulator; wherein two contact sockets include a lower contact socket and an upper contact socket; wherein the lower contact socket is fastened to the lower housing on the outside; wherein the upper contact socket is fastened to the upper housing on the outside; wherein the insulator electrically insulates the lower housing from the upper housing; wherein the lower housing and the upper housing are mechanically connected to each other by the insulator; wherein the lower housing, the upper housing, and the insulator, in the connected state, form at least one inner cavity; and wherein the sensor element and the assembly are arranged in the inner cavity.

[0027] The device has a three-piece housing consisting of a lower housing, an upper housing, and an insulator. Within the housing's interior cavity are a sensor element and two electrodes. Two contact sockets are externally secured to the lower and upper housing sections, transmitting the welding force to be measured to the sensor element within the cavity. This three-piece housing allows for simple and quick placement on the electrode arms and enables autonomous operation of the device. The insulator electrically isolates the lower and upper housing sections, preventing welding currents of tens of kA from flowing through the housing and distorting the sensor element's measurement of the welding force—a crucial condition for accurate welding force measurement.

[0028] In another preferred embodiment, the sensor element is arranged in the cavity within the main force path of the welding force.

[0029] By arranging the sensor element in the main force path, the welding force is applied almost entirely to the sensor element, resulting in high sensitivity. In the context of this invention, the term "sensitivity" refers to the ratio of the force value (Kraftwerte) generated by the sensor element under the welding force to the magnitude of the actual welding force applied. This sensitive sensor element has a low response threshold of less than or equal to 0.02 N for the welding force to be measured, enabling the sensor element to measure even very small welding forces with great accuracy.

[0030] In another preferred embodiment, the device has a first sensor element, a second sensor element, and a third sensor element; wherein the three sensor elements are the same single-component force sensor (Einkomponenten-Kraftaufnehmer), which measures the same welding force acting along the longitudinal axis; and wherein the three sensor elements generate force values ​​for the measured welding force.

[0031] Compared to multi-component force sensors, single-component force sensors have a lower purchase cost. Because the device has three identical single-component force sensors, the measurement range of the welding force is tripled compared to a device with only one single-component force sensor, thus improving the accuracy of the welding force measurement.

[0032] In another preferred embodiment, a first sensor element is arranged in a first inner cavity, a second sensor element is arranged in a second inner cavity, and a third sensor element is arranged in a third inner cavity; wherein the three sensor elements are located in a horizontal plane perpendicular to the vertical axis; wherein the three sensor elements are arranged at equal radial distances from the vertical axis; and wherein the three sensor elements are arranged at a uniform 120° angle relative to each other.

[0033] The symmetrical arrangement of the three sensor elements in the three cavities relative to the longitudinal axis largely avoids bending moments that would impact the device unilaterally in the horizontal plane and distort the welding force acting along the vertical axis, thus improving the accuracy of welding force measurement.

[0034] In another preferred embodiment, the component is arranged in a fourth cavity; wherein the component includes a lower electrode, an upper electrode, and an optical coupler; wherein the lower electrode is fastened to the lower part of the housing on the inside; wherein the upper electrode is fastened to the upper part of the housing on the inside; and wherein the optical coupler detects the welding voltage applied between the lower electrode and the upper electrode and converts it into a measurement value.

[0035] The component has two electrodes and an optocoupler for detecting and converting the welding voltage applied between the lower and upper parts of the housing during welding into a measurement value. This optocoupler is inexpensive and has electrically isolated input and output terminals. Therefore, welding voltages of a few volts (V) cannot enter the three-piece housing and cannot distort the sensor element's measurement of welding force, allowing for accurate measurement of the welding force.

[0036] In another preferred embodiment, the device has an analysis unit for analyzing force values; wherein the analysis unit is arranged in a fifth cavity; wherein the three cavities of the three sensor elements and the cavity of the assembly are connected to the fifth cavity of the analysis unit through a channel in the lower part of the housing; wherein the three sensor elements have electrical wires and transmit force values ​​to the analysis unit through the electrical wires; wherein the optocoupler has at least one electrical wire and transmits the measured value to the analysis unit through the electrical wire; and wherein the electrical wires of the three sensor elements and the electrical wires of the optocoupler are laid in the channel.

[0037] Therefore, not only the sensor elements and components, but also the analysis unit are arranged in a three-piece housing. This compact arrangement results in a significant reduction in the weight and size of the device. Consequently, the device can be mechanically and stably coupled to the welding clamp with relatively low coupling force, which can be performed simply and quickly and allows for autonomous operation of the device. The measured welding force is also analyzed within the device, thereby avoiding the need for the force value generated by the sensor element for the measured welding force to be transmitted through the external environment to the spatially distant analysis unit, as the force value may be distorted by harmful environmental factors along the path to the spatially distant analysis unit. This improves the accuracy of welding force measurement.

[0038] In another preferred embodiment, the device has an analysis unit for analyzing the measured welding force; wherein the sensor element has a piezoelectric material that generates polarized charges under the action of the welding force; wherein the sensor element conducts the polarized charges to the analysis unit; wherein the analysis unit has a charge amplifier that amplifies the polarized charges into a DC voltage; and wherein the analysis unit has calibration data of the sensor element, which the analysis unit uses to linearize the DC voltage.

[0039] Piezoelectric materials generate a force value in the form of polarized charges in response to the welding force to be measured. The amount of polarized charges is proportional to the magnitude of the welding force. However, due to external influences such as fluctuations and changes in ambient temperature, the force value may be measured with error. Therefore, the analysis unit amplifies the polarized charges into a DC voltage using calibration data from the sensor element and linearizes this DC voltage. Linearization reduces the measurement error of the force value. Generally, and in the context of this invention, the term "linearity" describes the deviation between the force signal generated by the sensor element under the action of the welding force and the magnitude of the actual welding force. Linearity is expressed as a percentage of the full-range signal (%FS). The linearized force signal of the device has a high linearity of less than or equal to 1%FS, and therefore describes the welding force to be measured with high accuracy. Compared to strain gauges, sensor elements made of piezoelectric materials have smaller measurement uncertainties. In the context of this invention, the term "measurement uncertainty" refers to the accuracy of the consistency of welding forces measured sequentially over time. The measurement uncertainty of sensor elements made of piezoelectric materials is less than or equal to 0.01%, which is about two orders of magnitude smaller than that of strain gauges.

[0040] In another preferred embodiment, the analysis unit provides a linearized DC voltage as an analog force signal and a digital force signal; wherein the analysis unit provides measured values ​​as analog measurement signals or digital measurement signals; wherein the device has an electrical feedthrough; wherein the analysis unit conducts the analog force signal and the digital force signal to the electrical feedthrough; wherein the analysis unit conducts the analog measurement signal and the digital measurement signal to the electrical feedthrough; and wherein the analog force signal and the digital force signal, as well as the analog measurement signal and the digital measurement signal, are selectively measured on the electrical feedthrough from the external environment of the device.

[0041] Therefore, the electrical feedthrough of the device can selectively measure not only analog and digital force signals, but also analog and digital measurement signals. This simplifies the measurement of welding force and the detection of welding voltage during the welding process, as the device can connect not only to analog measurement chains already existing in the external environment, but also to digital measurement chains. Further analysis of the force and measurement signals within these measurement chains can be performed, for example, to monitor the quality of the welding process. Attached Figure Description

[0042] The present invention will now be described in detail with reference to embodiments and the accompanying drawings. Wherein:

[0043] Figure 1 A partial cross-sectional view in the transverse plane YZ shows a first embodiment of the apparatus 1 for measuring welding force and detecting welding voltage during the welding process of the resistance welding equipment 2;

[0044] Figure 2 A partial cross-sectional view in the longitudinal plane XZ partially illustrates a second embodiment for measuring welding force and detecting welding voltage during the welding process in the resistance welding equipment 2;

[0045] Figure 3 A partial cross-sectional view in the transverse plane YZ partially illustrates a third embodiment for measuring welding force and detecting welding voltage during the welding process of the resistance welding equipment 2;

[0046] Figure 4 It shows according to Figure 1 An exploded view of a portion of a first embodiment of device 1;

[0047] Figure 5 It shows according to Figures 1 to 3 A perspective view of a portion of an embodiment of any one of the devices 1;

[0048] Figure 6 It shows according to Figure 1 A perspective view of the first embodiment of the device 1; and

[0049] Figure 7 It shows according to Figure 1 A perspective view of an embodiment of device 1 of or 2.

[0050] In all the accompanying drawings, the same objects are represented by the same reference numerals.

[0051] The list of reference numerals in the attached figures is as follows:

[0052] 1 device

[0053] 2 Resistance welding equipment

[0054] 10. Lower part of the shell

[0055] 10.1 First Inner Lumen

[0056] 10.2 Second Inner Lumen

[0057] 10.3 Third Inner Lumen

[0058] 10.4 Fourth inner cavity

[0059] 10.5 Fifth Inner Cavity

[0060] 10.6 channels

[0061] 10.7 Cover Plate

[0062] 10.8 Display device

[0063] 11. Upper part of the shell

[0064] 12-inch lower contact socket

[0065] 12.1 Lower tapered recess

[0066] 12.2 Lower Fasteners

[0067] 13. Upper contact socket

[0068] 13.1 Upper tapered recess

[0069] 13.2 Fasteners

[0070] 14 Couplers

[0071] 14.1 Coupler

[0072] 14.2 Tensioning elements

[0073] 14.21 Sleeve Components

[0074] 14.22 Tightening element

[0075] 14.23 Gripping Components

[0076] 14.3 Clamping elements

[0077] 14.31 End of the first clamping element

[0078] 14.32 End of the second clamping element

[0079] 14.33 Gap

[0080] 14.4 Other Fasteners

[0081] 14.5 Coupling opening

[0082] 14.51 Holding element

[0083] 15.1 First Sensor Element

[0084] 15.2 Second Sensor Element

[0085] 15.3 Third Sensor Element

[0086] 15.4 Lower Insulating Components

[0087] 15.5 Insulating element

[0088] 15.6 Preload Components

[0089] 16 Insulators

[0090] 17.1 Lower Electrode

[0091] 17.2 Upper Electrode

[0092] 17.3 Optical Coupler

[0093] 18 Analysis Units

[0094] 19 Electrical feeder

[0095] 20 Welding clamps

[0096] 20.1 Lower electrode arm

[0097] 20.2 Upper electrode arm

[0098] 21.1 Bracket

[0099] 21.2 Supporting elements

[0100] AKS analog force signal

[0101] DKS digital force signal

[0102] AMS Analog Measurement Signal

[0103] DMS Digital Measurement Signal

[0104] K coupling force

[0105] M Center of mass

[0106] R radial distance

[0107] TIS Technical Information Signal

[0108] X-axis

[0109] XY horizontal plane

[0110] XZ longitudinal plane

[0111] Y-axis

[0112] YZ horizontal plane

[0113] Z vertical axis Detailed Implementation

[0114] Figures 1 to 7 A device 1 is shown for measuring welding force and detecting welding voltage during the welding process in a resistance welding apparatus 2. Device 1 and the resistance welding apparatus 2 are arranged in a Cartesian coordinate system having a vertical axis X, a horizontal axis Y, and a vertical axis Z. The vertical axis X and the horizontal axis Y define a horizontal plane XY. The vertical axis X and the vertical axis Z define a longitudinal plane XZ. The horizontal axis Y and the vertical axis Z define a transverse plane YZ. In the following text, the term "below" is used for either device 1 or resistance welding apparatus 2 in accordance with... Figures 1 to 3 The objects arranged below the horizontal plane XY in the view, and the characteristic word "above" is used for device 1 or resistance welding equipment 2 according to Figures 1 to 3 Objects arranged above the horizontal plane XY in the view.

[0115] The resistance welding apparatus 2 has a welding clamp 20, which has a lower electrode arm 20.1 and an upper electrode arm 20.2. The lower electrode arm 20.1 may be fixed in position, while the upper electrode arm 20.2 is movable. Both electrode arms 20.1 and 20.2 are made of a conductive material such as copper or a copper alloy. The welding clamp 20 can be opened and closed by moving the upper electrode arm 20.2 along the vertical axis Z. The movement of the upper electrode arm 20.2 along the vertical axis Z is determined according to… Figure 1 and Figure 2 The image is represented by double arrows. During the welding process, welding force is applied along the vertical axis Z by electrode arms 20.1 and 20.2, and welding voltage is applied between electrode arms 20.1 and 20.2.

[0116] When the welding clamp 20 is opened, the device 1 can be placed on the electrode arms 20.1 and 20.2. For this purpose, the device 1 has a lower contact socket 12 and an upper contact socket 13. These two contact sockets 12 and 13 are made of a mechanically stabilizing material such as steel or tool steel. The lower contact socket 12 is cylindrical and has a lower conical recess 12.1. The upper contact socket 13 is also cylindrical and has an upper conical recess 13.1. Preferably, the two conical recesses 12.1 and 13.1 have an angle of 45° relative to the vertical axis Z. Each of the two conical recesses 12.1 and 13.1 can accommodate the foremost tip of the electrode arms 20.1 and 20.2 and is centered relative to the vertical axis Z. Preferably, the device 1 is placed on the electrode arms 20.1 and 20.2 by placing the lower contact socket 12 on the lower electrode arm 20.1. Here, the foremost tip of the lower electrode arm 20.1 is centered in the lower conical recess 12.1. When the welding clamp 20 is closed, the upper electrode arm 20.2 moves to the upper conical recess 13.1 and is centered there.

[0117] The device 1 has a lower housing portion 10 and an upper housing portion 11. The lower housing portion 10 and the upper housing portion 11 are made of a mechanically stabilizing material such as steel or tool steel. The lower housing portion 10 and the upper housing portion 11 are partially cylindrical.

[0118] Device 1 has a lower fastener 12.2 and an upper fastener 13.2. The lower fastener 12.2 and upper fastener 13.2 are made of a mechanically stabilizing material, such as steel or tool steel. Preferably, the lower fastener 12.2 and upper fastener 13.2 are bolts. The lower contact socket 12 is fastened to the lower housing portion 10 from the outside by the lower fastener 12.2. The term "outer side" refers to the side of the lower housing portion 10 opposite to the upper housing portion 11. The bolt-shaped lower fastener 12.2 extends through the opening of the lower contact socket 12, with the bolt head abutting against the lower contact socket 12 from the outside. It can be screwed into the threaded channel of the lower housing portion 10 to form a bolted connection. This bolted connection presses the lower contact socket 12 against the lower housing portion 10. The upper contact socket 13 is fastened to the upper housing portion 11 from the outside by the upper fastener 13.2. And the term "outer side" refers to the side of the upper housing portion 10 opposite to the lower housing portion 10. The upper fastener 13.2, in the form of a bolt, extends through the opening of the upper contact socket 13, with the bolt head resting against the upper contact socket 13 on the outside. It can be screwed into the threaded channel of the upper housing 11 to form a bolted connection. This bolted connection presses the upper contact socket 13 against the upper housing 11.

[0119] Device 1 has an insulator 16. The insulator 16 is made of an electrically insulating and mechanically rigid material, such as ceramic, polyimide, etc. The insulator 16 is arranged relative to the vertical axis Z between the lower part 10 and the upper part 11 of the housing. The insulator 16 electrically insulates the lower part 10 and the upper part 11 of the housing. The lower part 10 and the upper part 11 of the housing are mechanically connected to each other through the insulator 16.

[0120] The lower housing 10 and the upper housing 11, when connected, form at least one internal cavity 10.1-10.5. The mechanical connection between the lower housing 10 and the upper housing 11 is hermetically sealed. In the context of this invention, the term "hermetically sealed" means that moisture, liquid, and gas from the environment cannot enter the internal cavity 10.1-10.5. The environment is the three-dimensional space outside the device 1.

[0121] The device 1 has at least one sensor element 15.1-15.3 and an analysis unit 18, which are arranged in the inner cavity 10.1-10.5. The lower part 10 and the upper part 11 of the housing protect the sensor element 15.1-15.3 and the analysis unit 18 from harmful environmental influences, such as contaminants (dust, moisture, etc.) and electromagnetic interference in the form of electromagnetic radiation.

[0122] Sensor elements 15.1-15.3 measure the welding force applied by electrode arms 20.1 and 20.2 during the welding process. Sensor elements 15.1-15.3 generate force values ​​for the measured welding force. Sensor elements 15.1-15.3 are arranged relative to the vertical axis Z between the lower part 10 and the upper part 11 of the housing and located in the horizontal plane XY. Sensor elements 15.1-15.3 have sensor housings made of mechanically stabilizing materials such as steel or tool steel. Preferably, sensor elements 15.1-15.3 are hollow cylinders with two sensor end faces, two sensor side faces, and a central sensor hole. The sensor end faces are parallel to the horizontal plane XY. The axis of the central sensor hole is parallel to the vertical axis Z.

[0123] Preferably, sensor elements 15.1-15.3 are made of single crystal (e.g., quartz (SiO2), calcium gallium sub-germanate (Ca3Ga2Ge4O3)). 14 Or CGG), lanthanum gallium silicate (La3Ga5SiO) 14 Or LGS), tourmaline, gallium orthophosphate, etc.) and piezoelectric ceramics (e.g., lead zirconate titanate (Pb[Zr)) x Ti 1-x A piezoelectric material made of O3 (0 ≤ x ≤ 1, etc.) is used. Under the action of the welding force to be measured, the piezoelectric material generates a force in the form of piezoelectric charges. The piezoelectric material is oriented to have the highest sensitivity to the welding force acting along the vertical axis Z. In the sense of this invention, sensitivity refers to the ratio of the amount of polarization charge generated under the action of the welding force to the magnitude of the welding force acting on the piezoelectric material. At the highest sensitivity, the piezoelectric material generates the maximum amount of polarization charge.

[0124] According to Figure 5 and Figure 6 As shown in the perspective view, sensor elements 15.1-15.3 preferably consist of a first sensor element 15.1, a second sensor element 15.2, and a third sensor element 15.3. The first sensor element 15.1 is arranged in the first inner cavity 10.1. The second sensor element 15.2 is arranged in the second inner cavity 10.2. The third sensor element 15.3 is arranged in the third inner cavity 10.3. Preferably, all three sensor elements 15.1-15.3 are located in the horizontal plane XY. Preferably, the three sensor elements 15.1-15.3 are arranged at a radial distance R equal to that from the vertical axis Z. Preferably, the three sensor elements 15.1-15.3 are arranged at a uniform 120° interval relative to each other. Preferably, the center of gravity M of the device 1 is located within the radial distance R. Preferably, as... Figures 1 to 3 , Figure 5 and Figure 6 As shown, the center of mass M of device 1 is located basically on the vertical axis X.

[0125] Preferably, the three sensor elements 15.1-15.3 are identical and measure the same welding force acting along the longitudinal axis X. Preferably, sensor elements 15.1-15.3 are single-component force sensors, which measure the welding force acting along the vertical axis Z as the only force component. This single-component force sensor is commercially marketed by the applicant under model number 9133C and is described in datasheet 9130C_003-418d-04.21. The single-component force sensor has a central sensor hole with an outer diameter of 16.0 mm defined by the surface of an external sensor housing, an inner diameter of 6.1 mm, and a height of 3.5 mm between the sensor end faces. The sensitivity of the 9133C type single-component sensor is 4 pC / N.

[0126] The device 1 has a lower insulating element 15.4 and an upper insulating element 15.5. Both the lower insulating element 15.4 and the upper insulating element 15.5 are disc-shaped and have a central through-hole. The lower insulating element 15.4 and the upper insulating element 15.5 are made of an electrically insulating and mechanically rigid material, such as ceramic, polyimide, etc. The lower insulating element 15.4 is arranged about the vertical axis Z between the lower housing 10 and the sensor elements 15.1-15.3. The upper insulating element 15.5 is arranged about the vertical axis Z between the sensor elements 15.1-15.3 and the upper housing 11. Preferably, the device 1 has exactly one lower insulating element 15.4 and exactly one upper insulating element 15.5 for each sensor element 15.1-15.3. The lower insulating element 15.4 and the upper insulating element 15.5 electrically insulate the sensor elements 15.1-15.3 relative to the lower housing 10 and the upper housing 11. Therefore, sensor elements 15.1-15.3 are not at a potential of several volts (V) of welding voltage, which may distort the measurement of welding force.

[0127] Preferably, sensor elements 15.1-15.3 have measuring electrodes. The measuring electrodes measure polarization charges from the piezoelectric material. The measuring electrodes are not shown in the figures.

[0128] Preferably, the device 1 has at least one pre-tightening element 15.6. To ensure that the measuring electrode measures all generated polarization charges from the piezoelectric material, and that no polarization charges remain on the piezoelectric material, thus preventing distortion of the weld force measurement, the measuring electrode is mechanically pre-tightened relative to the piezoelectric material by the pre-tightening element 15.6. This mechanical pre-tightening seals the micropores between the measuring electrode and the piezoelectric material. Preferably, the device 1 has exactly one pre-tightening element 15.6 for each sensor element 15.1-15.3. The pre-tightening element 15.6 extends through the central through-hole of the lower insulating element 15.4, the central sensor holes of the sensor elements 15.1-15.3, the central through-hole of the upper insulating element 15.5, and an opening in the upper housing portion 11. Preferably, the pre-tightening element 15.6 is a bolt, which lies flat on the upper housing portion 11 with the bolt head facing outwards, and this bolt can be screwed into a threaded channel in the lower housing portion 10 to form a bolted connection. The bolted connection presses the sensor elements 15.1-15.3 against the lower housing 10. The term "on the outside" here also refers to the side of the upper housing 11 that is opposite to the lower housing 10.

[0129] Preferably, sensor elements 15.1-15.3 are arranged in the main path of the welding force within the cavities 10.1-10.5. Therefore, essentially the vast majority of the welding force acts on sensor elements 15.1-15.3 along the vertical axis Z, with only a small portion flowing through the insulator 16 and the preload element 15.6. In the context of this invention, the term "essentially" means "greater than / equal to 90%".

[0130] Sensor elements 15.1-15.3 have at least one electrical wire. This electrical wire is electrically connected to the analysis unit 18. Sensor elements 15.1-15.3 transmit the measured welding force as a force value to the analysis unit 18 via the electrical wire. Preferably, each of the three sensor elements 15.1-15.3 has an electrical wire.

[0131] Device 1 has at least one component 17.1-17.3. Preferably, components 17.1-17.3 are arranged in a fourth inner cavity 10.4. Preferably, components 17.1-17.3 include a lower electrode 17.1, an upper electrode 17.2, and an optocoupler 17.3. The lower electrode 17.1 is fastened to the lower housing 10 on its inner side. Here, the term "inner side" refers to the side of the upper housing 11 facing the lower housing 10. The upper electrode 17.2 is fastened to the upper housing 11 on its inner side. Here, the term "inner side" refers to the side of the lower housing 10 facing the upper housing 11. The lower electrode 17.1 and the upper electrode 17.2 are electrically connected to the optocoupler 17.3. The optocoupler 17.3 has input and output terminals that are electrically isolated from each other. Two electrodes 17.1 and 17.2 detect the welding voltage applied between electrode arms 20.1 and 20.2, and an optocoupler 17.3 converts the detected welding voltage into a measured value. The measured value applied to the output of the optocoupler is isolated from the welding voltage current applied to the input of the optocoupler. The measured value is a voltage whose amplitude is proportional to the magnitude of the welding voltage. The measured value can be a digital or analog measurement. The optocoupler 17.3 has at least one electrical wire that connects to the analysis unit 18 and transmits the measured value to the analysis unit 18.

[0132] The analysis unit 18 analyzes the force and measurement values. The analysis unit 18 is arranged in the fifth inner cavity 10.5. Preferably, the three inner cavities 10.1-10.3 of the three sensor elements 15.1-15.3 and the fourth inner cavity 10.4 of the assembly 17.1-17.3 are connected to the fifth inner cavity 10.5 of the analysis unit 18 through a channel 10.6 in the lower part of the housing 10. The electrical wires of the three sensor elements 15.1-15.3 and the electrical wires of the optocoupler 17.3 are laid in the channel 10.6 of the lower part of the housing 10.

[0133] The compact layout of the three sensor elements 15.1-15.3, one component 17.1-17.3, and one analysis unit 18 significantly reduces the weight and size of the device 1. Compared to the 9831C welding force calibration transmitter, the weight of the device 1 is reduced from 1.40 kg to less than half, at 0.64 kg.

[0134] The analysis unit 18 is a circuit with electrical and electronic components mounted on at least one circuit board. For insertion of the analysis unit 18 into the fifth inner cavity 10.5, the lower housing 10 has a cover plate 10.7. The cover plate 10.7 is made of a mechanically stable material such as steel or tool steel. The cover plate 10.7 is fastened to the lower housing 10. Fastening the cover plate 10.7 to the lower housing 10 achieves an airtight seal of the fifth inner cavity 10. The fastening of the cover plate 10.7 to the lower housing 10 is releasable. With the cover plate 10.7 loosened, the fifth inner cavity 10.5 can be accessed from outside the device 1 to insert the analysis unit 18.

[0135] The analysis unit 18 is electrically insulated relative to the lower housing 10 and the upper housing 11. Therefore, the analysis unit 18 is not at a potential of a few volts (V) of welding voltage, which may cause distortion in the analysis of the measured welding force and the measured welding voltage.

[0136] Preferably, the analysis unit 18 has a charge amplifier unit that amplifies the force value conducted through the conductor in the form of polarized charge into a DC voltage. This DC voltage is the analog force signal AKS of the analysis unit 18. Preferably, the analysis unit 18 digitizes the analog force signal AKS into a digital force signal DKS. Preferably, the analysis unit 18 has calibration data for sensor elements 15.1-15.3, and uses this calibration data to linearize the force signal. Here, the analysis unit 18 can linearize either the analog force signal AKS or the digital force signal DKS. Preferably, the calibration data is a calibration curve with coefficients of a polynomial function.

[0137] Preferably, the analysis unit 18 provides the measured value of the welding voltage detected during the welding process as an analog measurement signal (AMS) or a digital measurement signal (DMS).

[0138] According to Figures 3 to 7 In this embodiment, device 1 has an electrical feedthrough 19. The electrical feedthrough 19 is fastened to the lower portion 10 of the housing. The fastening of the electrical feedthrough 19 to the lower portion 10 of the housing is hermetically sealed. Preferably, the electrical feedthrough 19 is partially arranged in the fifth inner cavity 10.5. The electrical feedthrough 19 is electrically connected to the analysis unit 18. The analysis unit 18 can transmit force signals and measurement signals from the fifth inner cavity 10.5 to the outside of device 1 through the electrical feedthrough 19.

[0139] Preferably, an analog force signal AKS and a digital force signal DKS are selectively applied to the electrical feedthrough 19. Preferably, the analog force signal AKS and the digital force signal DKS applied to the electrical feedthrough 19 are linearized. Preferably, an analog measurement signal AMS and a digital measurement signal DMS are selectively applied to the electrical feedthrough 19. Preferably, the electrical feedthrough 19 has four electrical contacts. The analog force signal AKS and the analog measurement signal AMS, as well as the digital force signal DKS and the digital measurement signal DMS, are selectively applied to these four contacts. Through the electrical feedthrough 19, technical information signals TIS can also be read from the analysis unit 18, such as the model number of device 1, the serial number of device 1, the manufacturer's website of device 1, the calibration date of sensor elements 15.1-15.3, the measurement range of sensor elements 15.1-15.3, the sensitivity of sensor elements 15.1-15.3, the operational readiness status of device 1, etc. The Technical Information Signal (TIS) simplifies the measurement of welding force because it can be read from the measurement chain in the surrounding environment, and simplifies further analysis of the force and measurement signals in the measurement chain. Power supply voltage can be provided to the analysis unit 18 via the electrical feedthrough 19.

[0140] Electrical feedthrough 19 is electrically insulated from the lower housing 10 and the upper housing 11. Therefore, electrical feedthrough 19 is not at a potential of a few volts (V) of welding voltage, which could distort the transmission of force and measurement signals.

[0141] Even though device 1 can autonomously measure welding force and welding voltage, its operating status must still be monitored. For this purpose, device 1 has a display device 10.8. The display device 10.8 is secured to the lower part 10 of the housing. The securing of the display device 10.8 to the lower part 10 of the housing is hermetically sealed. The display device 10.8 has at least one lamp or screen. Technical information signals (TIS), such as the operating status of device 1, can be optically displayed on the display device 10.8 to an operator located outside device 1. Figure 5 and Figure 7 The display device 10.8 has five lights. To optically display the Technical Information Signal (TIS), the lights can illuminate in different colors, flash for different lengths, etc. The operating status of the device 1 can be "ready to run," "not ready to run," etc. The display device 10.8 is well visible to the operator even from a distance of 1 or 2 meters and allows for autonomous operation of the device 1. This makes it easy and quick to identify interference in the operating status of the device 1, which can then be eliminated by the operator, thus reducing the time required to measure welding force and welding voltage.

[0142] Device 1 has a coupling element 14. In Figure 1 In the first embodiment shown, the coupling member 14 is a clamping coupling. According to... Figure 2 In the second embodiment, the coupling element 14 is a form-fit coupling. According to... Figure 3 In the third embodiment, the coupling element 14 is a force-fit coupling. The coupling element 14 is made of a mechanically stabilizing material, such as steel, tool steel, aluminum, thermoplastic, etc.

[0143] According to Figure 1 In a first embodiment, the coupling 14 has a coupling body 14.1 and at least one additional fastener 14.4. The coupling body 14.1 is fastened to the lower contact socket 12 on the outside by the additional coupling 14.4. The term "outside" refers to the side of the lower contact socket 12 facing away from the lower housing 10. Preferably, the additional fastener 14.4 is a bolt that protrudes through an opening in the coupling body 14.1, with its head resting against the coupling body 14.1 on the outside, and can be screwed into a threaded channel in the lower contact socket 12 to form a bolted connection. This bolted connection presses the coupling body 14.1 against the lower contact socket 12.

[0144] According to Figure 1 In the first embodiment, the coupling member 14 has a clamping element 14.3. The clamping element 14.3 is integrally formed with the coupling body 14.1. Preferably, the clamping element 14.3 is formed on the outer side of the coupling body 14.1. The term "outer side" refers to the side of the coupling body 14.1 that faces away from the lower contact socket 12. The coupling body 14.1 and the clamping element 14.3 are hollow cylindrical.

[0145] According to Figure 1 In the first embodiment, the coupling member 14 has a coupling opening 14.5. The coupling opening 14.5 extends along the vertical axis Z through the coupling body 14.1 and the clamping element 14.3. The coupling opening 14.5 communicates with the tapered recess 12.1 of the lower contact socket 12. Therefore, by placing the coupling member 14 on the lower electrode arm 20.1, the device 1 can be placed on the electrode arms 20.1, 20.2, such that the lower electrode arm 20.1 extends through the coupling opening 14.5, and the foremost tip of the lower electrode arm 20.1 is centrally located in the lower tapered recess 12.1 of the lower contact socket 12. The diameter of the coupling opening 14.5 corresponds to the outer diameter of the lower electrode arm 20.1. The diameter of the coupling opening 14.5 and the outer diameter of the lower electrode arm 20.1 have a minimum mechanical clearance of preferably 0.1 mm.

[0146] According to Figure 1In the first embodiment, the clamping element 14.3 radially surrounds the coupling opening 14.5 arranged in the coupling body 14.1. The clamping element 14.3 has a first clamping element end 14.31 and a second clamping element end 14.32. These two clamping element ends 14.31 and 14.32 are spaced apart from each other by a gap 14.33. According to... Figure 6 In the perspective view, the gap 14.33 has a width of preferably 1 mm along the vertical axis X.

[0147] According to Figure 1 In the first embodiment, the coupling member 14 has a tensioning element 14.2. The tensioning element 14.2 is arranged on the clamping element 14.3. The tensioning element 14.2 has a sleeve element 14.21, a screwing element 14.22, and a gripping element 14.23. The sleeve element 14.21 is a hollow cylinder with a hollow axis. According to... Figure 6 In the perspective view, the sleeve element 14.21 extends along the longitudinal axis X. The sleeve element 14.21 is fastened to the end 14.31 of the first clamping element. The screwing element 14.22 is partially arranged in the hollow axis and held in the sleeve element 14.21 by form-fitting. The screwing element 14.22 has a first end and a second end. A gripping element 14.23 is mounted on the first end of the screwing element 14.22. Through the gripping element 14.23, the screwing element 14.22 can rotate about the longitudinal axis X. Figure 6In the perspective view, the rotatability of the screwing element 14.22 about the longitudinal axis X is indicated by a curved double arrow. The screwing element 14.22 has an external thread at its second end. By rotating about the longitudinal axis X, the external thread at the second end of the screwing element 14.22 is screwed into the threaded channel in the second clamping element end 14.32, forming a bolted connection. By rotating the screwing element 14.22 about the longitudinal axis X in the first direction, the screwing element is screwed into the second clamping element end 14.32. Since the screwing element 14.22 is held in the sleeve element 14.21, and therefore also in the first clamping element end 14.31 (on which the sleeve element 14.21 is fastened), the aforementioned rotation reduces the width of the gap 14.33 along the longitudinal axis X. The reduction in the width of gap 14.33 is more pronounced than the mechanical clearance between the diameter of coupling opening 14.5 and the outer diameter of lower electrode arm 20.1. This results in the device 1 being positioned on electrode arms 20.1 and 20.2, with lower electrode arm 20.1 extending through coupling opening 14.5. The reduced width of gap 14.33 causes lower electrode arm 20.1 to be clamped in clamping element 14.3, applying a coupling force K to lower electrode arm 20.1. Therefore, coupling element 14 and lower electrode arm 20.1 are coupled by clamping. The coupling force K is large enough to mechanically and stably couple device 1 to welding clamp 2. In the context of this invention, the term "mechanically stable coupling" means that device 1 is unshakably coupled to lower electrode arm 20.1 during operation of resistance welding equipment 2.

[0148] According to Figure 2 In a second embodiment, the coupling member 14 also has a coupling body 14.1. The coupling body 14.1 is arranged on the lower contact socket 12 on the outer side. The term "outer side" refers to the side of the lower contact socket 12 facing away from the lower housing 10. Preferably, the coupling body 14.1 is located in the lower conical recess 12.1 of the lower contact socket 12.

[0149] according to Figure 2The second embodiment of the coupling body 14.1 is also hollow cylindrical and has a coupling opening 14.5. This coupling opening 14.5 extends along the vertical axis Z through the coupling body 14.1. The coupling opening 14.5 communicates with the tapered recess 12.1 of the lower contact socket 12. The diameter of the coupling opening 14.5 corresponds to the outer diameter of the lower electrode arm 20.1. A retaining element 14.51 is arranged in the coupling opening 14.5. This retaining element 14.51 is annular and arranged in a groove of the coupling opening 14.5. The retaining element 14.51 is made of an elastic material, such as rubber, perfluororubber, etc. Preferably, two retaining elements 14.51 are arranged in the coupling opening 14.5. The retaining elements 14.51 arranged in the groove extend radially slightly into the coupling opening 14.5. Therefore, by placing the coupling member 14 on the lower electrode arm 20.1, the device 1 can be placed on the electrode arms 20.1 and 20.2, such that the lower electrode arm 20.1 extends through the coupling opening 14.5, and the foremost tip of the lower electrode arm 20.1 is centrally located in the lower conical recess 12.1 of the lower contact socket 12. Here, the retaining element 14.51 arranged in the recess is radially pressed by the lower electrode arm 20.1. Thus, the coupling member 14 and the lower electrode arm 20.1 are coupled in a form-fitting manner. The pressed retaining element 14.51 applies a coupling force K to the lower electrode arm 20.1.

[0150] exist Figure 3In the third embodiment shown, the coupling element 14 consists of only one other fastener 14.4. The resistance welding apparatus 2 has a bracket 21.1 and a support element 21.2. The bracket 21.1 is arranged close to the two electrode arms 20.1, 20.2, such that the device 1, when placed on these two electrode arms 20.1, 20.2, can be mechanically coupled to the bracket 21.1. The support element 21.2 is preferably made of an elastic material such as rubber or raw rubber, and elastically supports the device 1 on the bracket 21.1. Vibrations are damped by the support element 21.2 and cannot reach the device 1 from the resistance welding apparatus 2, thus preventing distortion of the measurement of welding force and the detection of welding voltage during the welding process. The device 1 is also electrically isolated from the potential of the resistance welding apparatus 2 by the support element 21.2, so that potential fluctuations in the resistance welding apparatus 2 do not affect the measurement of welding force and the detection of welding voltage during the welding process. Preferably, the other fastener 14.4 consists of two bolts. The bracket 21.1 has two through holes for these two bolts. Each bolt protrudes through a through-hole in bracket 21.1. Each bolt rests on bracket 21.1 with its head facing outwards. Each bolt can be screwed into a threaded channel in the lower housing 10, thus forming a bolted connection. The term "outer side" refers to the side of bracket 21.1 facing away from the lower housing 10. The bolted connection of the other fastener 14.4 presses the lower housing 10 against bracket 21.1. Coupling member 14 thus mechanically couples the lower housing 10 and bracket 21.1 by force engagement.

Claims

1. An apparatus (1) for measuring welding force and detecting welding voltage during the welding process of a resistance welding device (2), the resistance welding device (2) having a welding clamp (20) having two electrode arms (20.1, 20.2), the two electrode arms (20.1, 20.2) comprising a lower electrode arm (20.1) and an upper electrode arm (20.2). The device comprises: two contact sockets (12, 13) for placing the device (1) on the electrode arms (20.1, 20.2), the two contact sockets (12, 13) including a lower contact socket (12) and an upper contact socket (13), the lower contact socket (12) having a lower conical recess (12.1), the lower conical recess (12.1) receiving the foremost tip of the lower electrode arm (20.1) and being centered about the vertical axis (Z) when the device (1) is placed on the electrode arms (20.1, 20.2); at least one sensor element (15.1-15.3) for measuring the welding force applied by the electrode arms (20.1, 20.2) during welding; and at least one component (17.1-17.3) for detecting the welding voltage during welding. Its features are, The device (1) has a coupling member (14) which, when the device (1) is placed on the electrode arms (20.1, 20.2), mechanically couples the device (1) to the resistance welding equipment (2). In order to mechanically couple the device (1) to the resistance welding equipment (2), the coupling element (14) applies a coupling force (K) to the resistance welding equipment (2). The device (1) has a lower housing (10), an upper housing (11), and an insulator (16); the lower contact socket (12) is fastened to the outside of the lower housing (10); the upper contact socket (13) is fastened to the outside of the upper housing (11); the insulator (16) electrically insulates the lower housing (10) from the upper housing (11); the lower housing (10) and the upper housing (11) are mechanically connected to each other through the insulator (16); the lower housing (10) and the upper housing (11) form at least one inner cavity (10.1-10.5) in the connected state; and the sensor element (15.1-15.3) and the assembly (17.1-17.3) are arranged in the inner cavity (10.1-10.5).

2. The apparatus (1) according to claim 1, characterized in that, The coupling member (14) has a coupling body (14.1) which is fastened to the outside of the lower contact socket (12); the coupling body (14.1) has a coupling opening (14.5) which extends along the vertical axis (Z) through the coupling body (14.1) and communicates with the lower conical recess (12.1); with the device (1) placed on the electrode arms (20.1, 20.2), the lower electrode arms (20.1) extend through the coupling opening (14.5); The coupling element (14) applies the coupling force (K) to the lower electrode arm (20.1) in the coupling opening (14.5) to mechanically couple the device (1) and the resistance welding equipment (2).

3. The apparatus (1) according to claim 2, characterized in that, The coupling member (14) has a clamping element (14.3) radially surrounding the coupling opening (14.5); the clamping element (14.3) has a first clamping element end (14.31) and a second clamping element end (14.32), the first clamping element end (14.31) and the second clamping element end (14.32) being spaced apart from each other by a gap (14.33); and the reduction of the width of the gap (14.33) applies the coupling force (K) on the lower electrode arm (20.1).

4. The apparatus (1) according to claim 3, characterized in that, The coupling element (14) has a tensioning element (14.2) arranged on the clamping element (14.3); the tensioning element (14.2) has a sleeve element (14.21) and a screwing element (14.22); the sleeve element (14.21) is fastened to the end of the first clamping element (14.31) and holds the screwing element (14.22); and the screwing element (14.22) can be screwed into the end of the second clamping element (14.32) and the width of the gap (14.33) is reduced by this screwing.

5. The apparatus (1) according to claim 2, characterized in that, A retaining element (14.51) is arranged in the coupling opening (14.5); with the device (1) placed on the electrode arms (20.1, 20.2), the lower electrode arm (20.1) extends through the coupling opening (14.5) and presses against the retaining element (14.51); the pressed retaining element (14.51) applies the coupling force (K) to the lower electrode arm (20.1).

6. The apparatus (1) according to claim 1, characterized in that, The resistance welding equipment (2) has a support (21.1); the device (1) is mechanically coupled to the support (21.1) when placed on the electrode arms (20.1, 20.2); the coupling element (14) is made of an additional fastener (14.4); and the additional fastener (14.4) applies the coupling force (K) on the support (21.1) to mechanically couple the device (1) to the resistance welding equipment (2).

7. The apparatus (1) according to any one of claims 1 to 6, characterized in that, The sensor element (15.1-15.3) is arranged in the main force path of the welding force in the inner cavity (10.1-10.5).

8. The apparatus (1) according to any one of claims 1 to 6, characterized in that, The device (1) has a first sensor element (15.1), a second sensor element (15.2) and a third sensor element (15.3); the three sensor elements (15.1-15.3) are the same single-component force sensors that measure the same welding force acting along the longitudinal axis (X); and the three sensor elements (15.1-15.3) generate force values ​​for the measured welding force.

9. The apparatus (1) according to claim 8, characterized in that, The first sensor element (15.1) is arranged in the first inner cavity (10.1), the second sensor element (15.2) is arranged in the second inner cavity (10.2), and the third sensor element (15.3) is arranged in the third inner cavity (10.3); the three sensor elements (15.1-15.3) are located in a horizontal plane (XY) perpendicular to the vertical axis (Z); the three sensor elements (15.1-15.3) are arranged at the same radial distance (R) from the vertical axis (Z); and the three sensor elements (15.1-15.3) are evenly spaced apart from each other at an angle of 120°.

10. The apparatus (1) according to claim 9, characterized in that, The components (17.1-17.3) are arranged in the fourth inner cavity (10.4); the components (17.1-17.3) include a lower electrode (17.1), an upper electrode (17.2) and an optocoupler (17.3); the lower electrode (17.1) is fastened to the inner side of the lower part (10) of the housing; the upper electrode (17.2) is fastened to the inner side of the upper part (11) of the housing; and the optocoupler (17.3) detects the welding voltage applied between the lower electrode (17.1) and the upper electrode (17.2) and converts it into a measurement value.

11. The apparatus (1) according to claim 10, characterized in that, The device (1) has an analysis unit (18) for analyzing the force value; the analysis unit (18) is arranged in a fifth cavity (10.5); the three cavities (10.1-10.3) arranging the three sensor elements (15.1-15.3) and the cavity (10.4) arranging the assembly (17.1-17.3) are connected to the fifth cavity (10.5) of the analysis unit (18) through a channel (10.6) in the lower part (10) of the housing; the three sensor elements (15.1-15.3) have electrical wires and transmit the force value to the analysis unit (18) through the electrical wires; the optocoupler (17.3) has at least one electrical wire and transmits the measured value to the analysis unit (18) through the electrical wire; and the electrical wires of the three sensor elements (15.1-15.3) and the electrical wires of the optocoupler (17.3) are laid in the channel (10.6).

12. The apparatus (1) according to claim 10 or 11, characterized in that, The device (1) has an analysis unit (18) for analyzing the force value; the sensor element (15.1-15.3) has a piezoelectric material that generates polarized charges under the action of the welding force; the sensor element (15.1-15.3) conducts the polarized charges to the analysis unit (18); the analysis unit (18) has a charge amplifier that amplifies the polarized charges into a DC voltage; and the analysis unit (18) has calibration data of the sensor element (15.1-15.3) and uses the calibration data to linearize the DC voltage.

13. The apparatus (1) according to claim 12, characterized in that, The analysis unit (18) provides a linearized DC voltage as an analog force signal (AKS) and a digital force signal (DKS); the analysis unit (18) provides the measured value as an analog measurement signal (AMS) or a digital measurement signal (DMS); the device (1) has an electrical feedthrough (19); the analysis unit (18) transmits the analog force signal (AKS) and the digital force signal (DKS) to the electrical feedthrough (19); the analysis unit (18) transmits the analog measurement signal (AMS) and the digital measurement signal (DMS) to the electrical feedthrough (19); and the analog force signal (AKS) and the digital force signal (DKS), as well as the analog measurement signal (AMS) and the digital measurement signal (DMS), can be selectively measured from the external environment of the device (1) on the electrical feedthrough (19).

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