EP3025823A1 - Torque and rotation angle tool - Google Patents

Abstract

The invention relates to a torque and rotational angle tool (10) for measuring and / or tightening a torque (M) and a rotation angle (Õ) on a screw connection. The torque and rotation angle tool (10) includes a housing (23) with a handle (22) and a lever arm (12) for transmitting the torque (M). A torque measuring device (34) detects the torque (M) electronically. A rotation angle measuring device (36) detects the rotation angle (Õ) electronically. Measuring and control electronics process the torque and angle of rotation thus detected. A device (30) for determining the tightening status of the screw connection, whether the screw connection has already reached a target torque, is provided.

Description

Technical area

1. a) ein Gehäuse mit einem Griff,
2. b) einen Hebelarm zum Übertragen des Drehmoments,
3. c) eine Drehmomentmesseinrichtung zur elektronischen Erfassung des Drehmoments und
4. d) eine Drehwinkelmesseinrichtung zur elektronischen Erfassung des Drehwinkels,
5. e) eine Mess- und Steuerelektronik zum Verarbeiten des erfassten Drehmoments und des Drehwinkels,
6. f) eine Einrichtung zum Ermitteln des Anzugstatus der Schraubverbindung, ob die Schraubverbindung bereits ein Solldrehmoment erreicht hat.

The invention relates to a torque and rotation angle tool for measuring and for tightening a torque and a rotation angle on a screw connection, comprising

1. a) a housing with a handle,
2. b) a lever arm for transmitting the torque,
3. c) a torque measuring device for the electronic detection of torque and
4. d) a rotational angle measuring device for electronically detecting the angle of rotation,
5. e) measuring and control electronics for processing the detected torque and the angle of rotation,
6. f) means for determining the tightening status of the screw, whether the screw has already reached a target torque.

description

The screw connection is the most commonly used connection in mechanical engineering. Such fasteners can only be effective through the use of suitable assembly tools. Among the suitable assembly tools include torque and angle tools, as they are mentioned. Torque tools are needed to apply a specific torque to a workpiece. Torque tools such as torque wrench or torque screwdrivers are known.

There are mechanical and electronic torque tools. In particular, there are indicating and triggering torque tools. Indicating torque tools always indicate the respective applied torque. With triggering torque tools, a setpoint torque is set. Once this torque is achieved when tightening a screw, the torque tool signals the achievement of the desired torque to a user. This can be signaled, for example, by an audible click or tactile click.

The torque to be transmitted when using hand-guided tools depends on the physical constitution of the user as well as on his subjective sense of strength. Torque tools are used to load a bolt with a high preload force that is within the elastic range of the bolt or also to load the bolt with only slight preload forces. The use of new construction materials such. As magnesium, aluminum or plastic, especially for lightweight construction in the automotive or aircraft industry can both the demand, as well as the requirements for the torque tools increase. These new materials increase the number of sensitive screw connections. The lower tensile strength of these lightweight materials compared to steel materials would in a Overuse of the screw lead to damage the thread that would make these expensive components unusable.

Angle measuring devices for measuring the tightening angle are used inter alia in a rotational angle controlled tightening of screws or nuts. In this case, for example, with a torque wrench a screw is tightened up to a predetermined setting torque. Upon reaching the set torque, a screw has set, d. H. All elements involved, such as a screw head, a nut and workpieces to be joined are - after flattening all unevenness - smooth each other. Subsequently, a further tightening by a further rotation by a certain predetermined rotation angle. As a result, an optimal preload force of the screw is achieved.

There are known combination tools that combine the torque wrench and the angle measuring device for measuring the tightening angle. In this case, a torque is transmitted to the screw with the torque wrench up to a target torque. Thereafter, the screw is tightened by a defined angle of rotation with the same tool.

In practice, it comes again and again to assembly errors, since individual screws of a complex assembly are not tightened. One cause of the error is that screws are double and others are not tightened at all. Electronic torque wrenches that register the tightened bolted connection as part of a schedule can not automatically detect the error described above.

Such tools are used in many ways in the assembly. Here, a fitter has a schedule, which screw he has to tighten in what order with what torque and angle of rotation.

For example, a fitter has to tighten ten bolts in this schedule. During installation, the installer accidentally double-tightens a screw (e.g., number eight). When the number nine bolt is reached, however, the schedule has been completed. Namely, ten screw connections were recorded by the electronic torque wrench. The installer releases the assembly for the next assembly step, although a bolted connection has not been tightened correctly.

This is particularly critical when screws are first advanced with a torque to then tighten them in a second pass to the rated torque. If the error occurs during the second pass, the error can no longer be detected even in the case of an optical control, since an optical fixed screw connection has usually already been created.

State of the art

It is known that a screw connection initially has a very flat torque gradient during the assembly process. The torque gradient is defined as an increase in torque over a helix angle interval. The torque gradient is determined solely by the friction losses in the screw thread. If the set torque is reached during an assembly process, i.e., the screw head touches down, the torque gradient increases significantly over the same screw angle interval. The cause is the additionally occurring Unterkopfreibung the screw.

Also known are electronic torque-angle wrench as a hand-operated tools for controlled tightening a screw. These tools usually detect mechanical stresses in a bending or torsion element with strain gauges. Alternatively, piezocrystals or micromechanical components (MEMS) can be used to detect the mechanical stress. The voltages detected in this way are based on adjusting and further correction parameters in a computer unit converted into a torque. The angle of rotation is usually recorded and calculated with referenceless tools with group or acceleration sensors. Adjustment and further correction parameters are also used here.

The EP 1 310 333 A1 discloses a torque wrench for follow-up pull-on test. The torque wrench described there serves to tighten a pin, such as a screw that is already in a tightened condition. The torque wrench comprises a torque detecting means for detecting a torque when tightening the screw, wherein the torque detecting means is disposed in a wrench body. Furthermore, there is described a rotation angle detection means for detecting a rotation angle of the torque wrench. The rotation angle detecting means is arranged in the wrench body.

The torque wrench has a first calculating means for estimating a torque characteristic in a rotating state of the pen in response to input information. The torque characteristic has been recorded in a stable area after the rotation of the pin. It is a characteristic reference characteristic for the torsion set in advance. From the torque information and the rotation angle, the input information is formed.

A second arithmetic means estimates a torque characteristic in a stationary state of the stylus obtained from the input information before rotation of the stylus.

With a third calculating means, the intersection between the torque characteristic in the rotating state and the torque characteristic in the stationary state is determined. From this, a torque value at the intersection is determined as a torque measurement.

Disclosure of the invention

The object of the invention is therefore to avoid the disadvantages of the prior art and to provide a torque and rotation angle tool with simple means which determines uncomplicated whether a screw is already attracted to a target torque and a target rotation angle or not.

• g) eine prozessorgesteuerte Auswerteeinrichtung zur Berechnung des Gradienten des Anzugsmoments vorgesehen ist, wobei das Anzugsmoment in einem festgelegten Winkelintervall gemessen und mit einem Solldrehmomentgradienten verglichen wird.

According to the invention the object is achieved in that in a torque and rotation angle tool for measuring and / or tightening a torque and a rotation angle of a screw of the type mentioned

• g) a processor-controlled evaluation device is provided for calculating the gradient of the tightening torque, wherein the tightening torque is measured in a defined angular interval and compared with a setpoint torque gradient.

A bolted connection initially has a very flat torque gradient during the assembly process. The torque gradient is defined as a torque increase over a helix angle interval. The torque gradient initially arises solely by the friction losses in the screw thread. From a set moment, when the screw head touches, the torque gradient increases rapidly over the same screw angle interval. To the thread friction then comes namely the Unterkopfreibung the screw. In a rotation angle interval, the increase of the torque gradient from a starting torque to the setting torque is relatively small.

However, from the seating moment at which the screw head touches down, the increase in torque gradient is significant. The present invention takes advantage of this fact. By determining the respective torque gradient within an angular interval and the comparison with a desired value, it can be determined whether a screw connection has already been tightened or only advanced. This torque-rotation angle tool according to the invention makes the suit of Screw connections safer, because this can be ensured if a screw was actually tightened or forgotten. Often optical controls alone are not sufficient if a pre-tightening of a screw connection already exists.

In an advantageous embodiment of the torque and rotation angle tool according to the invention, the processor-controlled evaluation device has evaluation means which determine the detected rotation angle at a rated torque and compare it with a desired value. This measure serves to measure and evaluate the torque in relation to a defined angular interval in the case of a fixed screw connection starting from a defined torque. The limit value defines a maximum torque. A torque limit value is individually defined by the user with regard to the screw connection and their behavior in the screwing process. In a loose screw a large angle of rotation is exceeded with a very small torque gradient. The set limit is therefore not reached. On the other hand, if the screw connection has already been advanced or even tightened to a nominal torque, the torque gradient rises very rapidly over a small angle of rotation, so that the torque limit value is reached or exceeded.

A further preferred embodiment of the torque and rotational angle tool according to the invention consists in that a display, which is controlled by the evaluation device, signals a deviation of the measured gradient of the tightening torque from the setpoint torque gradient. This measure serves to represent the user when screw connections are not tightened correctly. Here, for example, the flowchart when tightening a set of screws can be displayed. Among other things, it can be shown which screw connections still have to be tightened. The display can also serve to make the torque rotation angle profile visible to the user. The display can also be activated for the operation of the torque / rotation angle tool.

The torque and rotation angle tool according to the invention preferably has an electromechanical, acoustic and / or optical signal generator, which is controlled by the evaluation device. This measure helps the user to recognize when a setpoint value, such as a setpoint torque, a setpoint rotation angle or a setpoint torque gradient has been reached. Other error messages can also be signaled to the user in this way. The signal generator is therefore controlled regularly by the evaluation device.

As an advantageous embodiment of the invention has also been found if the torque and rotation angle tool has an optical sensor which detects the respective threaded connection to be processed. The optical sensor can be designed, for example, as a photoelement. The optical sensor visually detects a screw connection and arranges it accordingly in the flow chart. In this way it is already possible to visually determine whether a screw has been tightened before or not yet.

Further advantages and refinements emerge from the subject matter of the subclaims, as well as the drawings with the associated descriptions. An exemplary embodiment will be explained in more detail below with reference to the drawings. However, the invention should not be limited solely to this embodiment. In the future technical means may be provided to the person skilled in the art which are basically covered by the wording of the invention but which are not explicitly described in the exemplary embodiment.

Short description of the drawing

Fig. 1

shows a schematic diagram of a torque-angle wrench according to the invention.

Fig. 2

shows a functional diagram of the electronic components of a torque-angle control key according to the invention.

Fig. 3

shows in a schematic diagram the torque-rotational angle curve of a screw connection.

Fig. 4

shows in a schematic diagram of the torque angle of rotation of a fixed screw.

Fig. 5

shows in a schematic diagram the comparison of a fixed and a prior compound.

Preferred embodiment

In Fig. 1 is a schematic diagram of an inventive torque-angle wrench 10 is shown. The torque-angle key 10 includes a lever arm 12. At a front end 14 of the lever arm 12, a head portion 16 is provided with a driving part 18. At a rear end 20 of the lever arm 12, a handle 22 is arranged, which is designed as a housing 23. On the handle 22, a display 24 is provided with controls 26. With the operating elements 26 of the torque angle key 10 is set and operated.

A torque is transmitted from the handle 22 to the head part 16 via the lever arm 12. At the head part 16, the drive part 18 with a plug-in or Plug-on tool 28 is provided. The plug-in or Aufsteckwerkzeug 28 transmits the torque to a - not shown - screw. The plug-in tool is usually inserted into a square socket profile. The Aufsteckwerkzeug 28 is plugged accordingly on an external square profile. Below the display 24 and within the handle 22, an electronic control and processing device 30 is provided in the housing 23. On the one hand, the control and processing device 30 is actuated by a user (not shown here) via the operating elements 26 for operating the torque angle-wrench 10. On the other hand, the control and processing device 30 records the acquired measurement data, stores it, and then processes it. The control and processing device 30 (see FIG. 2 ) controls the display 24, for example, to display the measurement data and / or an evaluation or represent operator menus.

The applied torque is measured by means of strain gauges 32 (see FIG. 2 ). The strain gauges 32 are components of a torque measuring device 34. The strain gauges 32 detect the stress in a bending element. The flexure deflects upon application of torque to the torque wrench 10. The strain gages 32 are secured to the flexure and detect the flexing of the flexure. This bending of the flexure is converted by the strain gauges 32 into an electrical signal. The electrical signal, which corresponds to the respective applied torque, can be processed by the control and processing device 30.

The torque angle wrench 10 further has a rotation angle measuring device 36 for detecting the rotation angle to be measured. Here, the measurement of the rotation angle is started at a start time. In this case, the rotational angle measuring device 36 can be started, for example, by the brehmomentmesseinrichtung 34.

Fig. 2 shows in a Funktionssskizze the electronic components 37 of the torque-angle wrench 10 according to the invention one or more strain gauges 32 detect the voltage in the bending element of the torque angle wrench. From this electrical signal, which is generated by the strain gauges 32, the torque applied to the torque angle key 10 is finally determined. The reference numeral 38 denotes an analog signal processing for processing the electrical signals of the strain gauges 32. An analog-to-digital converter 39 converts these processed analog signals into digital signals. The digital values of the signals are fed to a computing and storage unit 40.

A gyroscope 42 detects the swept angle of rotation of the rotary angle torque wrench 10. Instead of the gyroscope 42, acceleration sensors may also be used. The signal of the gyroscope 42 is converted via a further analog-to-digital converter 44 into a digital signal. The value of the digital signal is forwarded to the arithmetic and storage unit 40.

An optical sensor 46, which is formed for example by a photoelement, detects the respective screw connection to be processed. The signal of the optical sensor 46 is in turn converted via a third analog-to-digital converter 47 into digital values, which are further processed in the computing and storage unit 40.

The torque and rotation angle key 10 is operated via the operating elements 26 by a user. The operating elements 26 consist for example of the input elements: keys, decoder and digital interface for setting the desired parameters.

The torque measuring device 34 and the rotation angle device 36 are formed by the electronic components strain gauges 32, gyroscope 42, the analog-to-digital converters 39 and 44, and the computing and storage unit 40.

The input signals generated by the strain gages 32, the gyroscope 42, the optical sensor 46 and the operating elements 26 are processed by the computing and storage unit 40. The values generated therefrom by the computing and storage unit 40 are output on the display 24, which preferably consists of an OLED display. However, the computing and storage unit 40 may also drive a signal generator 48, such as LEDs, a buzzer or an electromechanical signal generator. The signal generator 48 is actuated upon reaching a preset torque or angle of rotation of the computing and storage unit 40.

Fig. 3 shows in a schematic diagram the torque-rotational angle curve 50 of a screw connection. A screw connection initially has a very flat torque gradient during the assembly process. The torque gradient is defined as a torque increase M ₂ -M _i / <φ ₂ -φ ₁ over a helix angle interval φ ₂ -φ ₁ . Here, M is always the name for a torque and φ denotes an angle. The torque gradient is determined by the friction losses in the screw thread alone. If the setting moment is reached during the assembly process, that is to say that the screw head touches down, the torque gradient increases significantly over the same screw angle interval. The cause is the additionally occurring Unterkopfreibung the screw. In the principle diagram of FIG. 3 is shown on the horizontal axis 52 of the rotation angle and on the vertical axis 54, the torque. In a rotation angle interval φ ₂ -φ ₁ , the increase of the torque gradient M ₂ -M ₁ / φ ₂ -φ ₁ from a starting torque M ₀ to a set torque is relatively small. From the setting moment at which the screw head touches on, the increase of the torque gradient M ₄ -M ₃ / φ ₄ - φ ₃ compared to the torque gradient M ₂ -M ₁ / φ ₂ - φ _{1 is} considerable. In this case, the rotation angle interval φ ₂ - φ ₁ = φ ₄ - φ ₃ , which is the basis, unchanged. The screw connection is tightened up to a setpoint torque or rated torque, the desired or required torque.

Fig. 4 shows in a schematic diagram the torque angle of rotation curve 50 of a fixed screw connection. On the horizontal axis 52 in turn the angle of rotation and on the vertical axis 54, the torque is applied. Here the course starts at the starting torque M ₀ , which corresponds to the setting torque. Due to the thread friction of the screw connection and the Unterkopfreibung is the increase of the torque-rotational angle curve 50, so the torque gradient M ₂ -M ₁ / φ ₂ - φ ₁ , relatively strong. The screw connection is tightened up to the nominal torque.

Fig. 5 shows in a schematic diagram the comparison of a fixed and a pre-screwed connection. On the horizontal axis 52 is the angle of rotation and on the vertical axis 54, the torque is applied. The torque-rotation angle profile 50 of the preceding screw connection is designated by the reference numeral 56 here. The torque-rotation angle profile 50 of the fixed screw connection is denoted by reference numeral 58 here. Here the course starts at the starting torque M ₀ . It can be seen that the increase of the torque rotation angle profile 50 of the preceding screw connection 56 is flatter than the torque rotation angle profile of the fixed screw connection 58. Comparing the rotational angle profiles 50 of the preceding 56 and the fixed screw connection 58, it can be determined that a setpoint torque Nominal torque M _{N is achieved} by the fixed connection faster by the steeper rise.

In principle, two methods for detecting an already advanced screw connection 56 or 58 can be carried out with the torque angle wrench 10 according to the invention.

In a first case, the torque M ₂ -M ₁ / φ _2, during the screwing, from a specified starting torque M _0, - φ ₁ relative to a predetermined angle interval φ ₂ - φ ₁ measured and evaluated. The limit value defines a maximum torque gradient. The specifications of the starting torque M ₀ , angle interval φ ₂ - φ ₁ and torque gradients M ₂ -M ₁ / φ ₂ - φ ₁ are determined by the user with respect to the screw connection and their behavior in the screwing process. These values may be passed to the torque angle key as parameters, for example, via the controls 26.

If the screwing process is started with a "loose screw connection", a large turning angle with a very small torque gradient is first exceeded, as well as in Fig. 3 you can see. On the other hand, if the screw connection has already been advanced or has been tightened to the nominal torque M _N , the torque gradient M ₂ -M ₁ / φ ₂ -φ _{1 increases} very rapidly over a small rotational angle interval φ ₂ -φ ₁ . If this behavior is considered over a defined angle of rotation interval, the already tightened screw connection can be detected automatically. The torque angle key 10 detects the torque M and the rotation angle φ throughout the screwing operation. Both values are processed in the arithmetic and memory unit 40 and compared with the stored limit values. If the limit value for the torque gradient M ₂ -M ₁ / φ ₂ -φ ₁ is exceeded, an optical and acoustic warning via the signal generator 48 to the user takes place automatically. This can cancel the screwing and correct the assembly error. This provision can preferably be applied to "soft screw connections", in which the torque gradient between a loose and tightened screw sufficiently different.

For a fixed screw 58, the torque wrench 10 uses a different approach. During the screwing process, starting from a defined torque, the torque is measured and evaluated in relation to a defined angular interval φ ₂ -φ ₁ . The limit value defines a maximum torque. The definitions of the starting torque M ₀ , angle interval φ ₂ - φ ₁ and torque limit M _N are individually determined by the user with respect to the screw connection and their behavior in the screwing process. These values can be passed to the torque angle key 10 via the controls 26 again as a parameter accordingly. Will the screwing process started with a "loose screw", one first exceeds a large angle of rotation with a very small torque gradient. The set limit is not reached or exceeded. On the other hand, if the screw connection has already been advanced or has been tightened to the nominal torque M _N , the torque gradient M ₂ -M ₁ / φ ₂ -φ _{1 increases} very rapidly over a small angle of rotation, so that the torque limit value is reached or exceeded. The screw is recognized as already tightened and there is automatically a visual and audible warning via the signal generator 48 to the user. If necessary, this can stop the screwdriving process and continue the screwing process on the correct screw connection.

10

Drehmoment-Drehwinkelschlüssel

12

Hebelarm

14

Vordere Ende des Hebelarms 12

16

Kopfteil

18

Antriebsteil

20

Hintere Ende des Hebelarms 12

22

Handgriff

23

Gehäuse

24

Anzeige (OLED)

26

Bedienungselemente (IN)

28

Einsteck- bzw. Aufsteckwerkzeug

30

Steuer- und Verarbeitungseinrichtung

32

Dehnungsmessstreifen (DMS)

34

Drehmomentmesseinrichtung

36

Drehwinkelmesseinrichtung

37

elektronische Komponenten

38

analoge Signalaufbereitung (AG)

39

Analog-Digital-Wandler (ADC)

40

Rechen- und Speichereinheit (CPU)

42

Gyroskop (GYRO)

44

Analog-Digital-Wandler (ADC)

46

Optischer Sensor (OS)

47

Analog-Digital-Wandler (ADC)

48

Signalgeber (SG)

50

Drehmoment-Drehwinkelverlauf

52

horizontalen Achse

54

vertikalen Achse

56

Drehmoment-Drehwinkelverlauf einer vorangezogenen Schraubverbindung

58

Drehmoment-Drehwinkelverfauf einer festen Schraubverbindung

If it is a hard screw connection or if the pre-tightening torque is just below the nominal torque of the screw connection, there is no reliably detectable difference between the two torque gradients. In this case, the screw connection must be tightened to the nominal torque M _N. The angle of rotation φ is measured. The detection in this method takes place via the rotation angle φ. In a loose screw connection a larger angle of rotation φ ₄ - φ _{2 is} exceeded than in a fixed screw φ ₃ - φ _{1 of} the same type. The torque angle key detects the torque M and the rotation angle φ throughout the tightening operation. Both values are calculated and compared with the stored limit values. If the limit value of the rotation angle φ is exceeded, an optical and acoustic warning via the signal generator 48 to the user takes place automatically. This can cancel the screwing and correct the assembly error.

10

Torque-angle wrench

12

lever arm

14

Front end of the lever arm 12

16

headboard

18

driving part

20

Rear end of the lever arm 12

22

handle

23

casing

24

Display (OLED)

26

Controls (IN)

28

Plug-in or Aufsteckwerkzeug

30

Control and processing device

32

Strain gages (DMS)

34

Torque measuring device

36

Rotation angle measurement device

37

electronic components

38

analog signal conditioning (AG)

39

Analog-to-digital converter (ADC)

40

Computing and storage unit (CPU)

42

Gyroscope (GYRO)

44

Analog-to-digital converter (ADC)

46

Optical sensor (OS)

47

Analog-to-digital converter (ADC)

48

Signal generator (SG)

50

Torque rotational angle course

52

horizontal axis

54

vertical axis

56

Torque angle of rotation of a previous screwed connection

58

Torque-Drehwinkelverfauf a fixed screw

Claims (5)

Torque and rotation angle tool (10) for measuring and / or for tightening a torque (M) and a rotation angle (φ) at a screw connection, comprising a) a housing (23) with a handle (22), b) a lever arm (12) for transmitting the torque (M), c) a torque measuring device (34) for the electronic detection of the torque (M) and d) a rotational angle measuring device (36) for the electronic detection of the rotational angle (φ), e) measuring and control electronics for processing the detected torque and the angle of rotation, f) a device (30) for determining the tightening status of the screw connection, whether the screw connection has already reached a setpoint torque,
characterized in that g) a processor-controlled evaluation device (40) for calculating the gradient (M ₂ -M ₁ / φ ₂ - φ ₁ ) of the tightening torque is provided, wherein the tightening torque is measured at a predetermined angular interval φ ₂ - φ ₁ ) and compared with a setpoint torque gradient , Torque and rotation angle tool (10) for measuring and / or for tightening a torque and a rotation angle (φ) on a screw connection, according to claim 1, characterized in that the processor-controlled Evaluation device (40) has evaluation means which determine the detected rotation angle (φ) at a nominal torque (M _N ). Torque and rotation angle tool (10) for measuring and / or for tightening a torque (M) and a rotation angle (φ) to a screw, according to one of claims 1 or 2, characterized in that a display (24), which of the Evaluation device (40) is driven, a deviation of the measured gradient (M ₂ -M ₁ / φ ₂ - φ ₁ ) of the tightening torque of the target torque gradients signaled. Torque and rotation angle tool (10) for measuring and / or for tightening a torque and a rotation angle (φ) to a screw, according to one of claims 1 to 3, characterized by an electromechanical, acoustic and / or optical signal generator (48) is controlled by the evaluation device (40). Torque and rotation angle tool for measuring and / or tightening a torque and a rotation angle to a screw, according to one of claims 1 to 4, characterized in that an optical sensor (46) is provided, which detects the respective threaded connection to be processed.

Images