DE102015103903A1 - Power wrench with direct rotation angle and / or torque measurement - Google Patents

Abstract

The present invention relates to a device (20) for the pneumatic or hydraulic drive of a shaft (11, 12) with a tool holder, a housing (1), a torque arm (3, 5, 9), which at least with a portion of the housing for receiving a reaction torque and at least one sensor (4, 10, 13) for determining a reaction torque, which is connected to a signal processing device (7), wherein at least the torque arm (3, 5, 9) and / or the shaft (11 , 12) form a reaction element which has at least one line of tension during operation. The invention is characterized in that the sensor (4, 10, 13) in a region of at least one voltage line, preferably in the region of the maximum voltage lines of the torque arm (3, 5, 9) and / or shaft (11, 12), in Operation of the device (20) detects at least one change in length and determined by the signal processing means (7) and predetermined parameters, an action torque of the shaft (11, 12) in the tool holder.

Description

The present invention relates to a power wrench with a torque arm, in which by means of direct rotation angle and / or torque measurement essential Verschraubungsparameter be determined independently or a torque arm with at least one sensor for direct determination of a torque of a power wrench.

Power wrenches are known in the art. They serve by means of a shaft (drive shaft), at the end of a tool holder is arranged screw in or loosen screws. Power wrenches are used in particular for large machines or equipment. Torques in the range of several thousand Newton meters often occur on the shaft.

In particular, hydraulic or pneumatic screwing tools are indirectly controlled according to the prior art. In indirect control (as defined in VDI / VDE guideline 2862 sheet 2 ) is used - usually measured at the pressure source - hydraulic (or pneumatic) pressure of the power supply for calculating the desired torque value at the shaft used. The following is usually spoken of hydraulic devices. However, this implies that the devices and methods of the invention are analogously applicable to pneumatic devices and methods.

Such a device with indirect control has the following disadvantages, among others:
Especially at higher flow rates of the hydraulic fluid results in a systematic measurement error due to the back pressure. Therefore, in the prior art - to make these systems sufficiently accurate - usually worked with relatively low flow rates, thereby keeping the back pressure low and thus to achieve the required precision.

A particular difficulty arises with so-called intermittently working hydraulic tools. These are typically used in tools that have a ratchet function. In such power wrenches is quite often, namely at each ratchet step, the stroke end of the tool achieved. In indirect-control power wrenches, the hydraulic pressure continues to rise without any further increase in torque.

In other devices according to the prior art, the rotation angle of the shaft is required as a measured value. For example, in devices that operate according to the so-called torque-rotation angle method, the rotation angle of the shaft (tool spindle) is used; This method allows a tightening in the elastic and over-elastic range. Another example is the so-called gradient method, which allows yield-strength-controlled tightening. According to the prior art, the angle of rotation of the shaft via a flow sensor, ie indirectly, is measured, which also leads to a high inaccuracy in the determination of the rotation angle.

Against this background, it is an object of the present invention to provide a power wrench which at least partially overcomes or improves the above-described disadvantages of the prior art. In addition, a torque arm with a sensor for determining the torque is provided on a reaction element of the power wrench, which is connectable with a power wrench known in the art and thus at least partially overcomes or improves the disadvantages known in the prior art.

These and other objects are achieved by a torque arm and a power wrench according to independent claims 1 and 2 and a method according to independent claim 8. Embodiments and developments of the present invention are subject of the dependent claims.

A device according to the invention for the pneumatic or hydraulic drive of a shaft with a tool holder has at least one torque support and a housing, wherein the torque support is rotatably connected at least with a portion of the housing. This section of the housing is used to receive a reaction torque. At least one sensor for determining a reaction torque is arranged in this section of the housing. This sensor is connected to a signal processing device. At least the torque support and / or the driven shaft forms a reaction element which has at least one voltage line in operation in the device.

The sensor is arranged in a region of the at least one voltage line, preferably in the region of the maximum voltage lines of the reaction element such as the torque arm, and detects at least one change in length in the measuring field during operation of the device. Based on this change in length and predetermined parameters, the signal processing device, which is connected to the sensor, determines an action torque of the shaft in the area of the tool holder.

In this case, the present invention comprises both the combination of a power wrench in the form of a device for pneumatic or hydraulic drive of a shaft with a correspondingly equipped torque arm, as well as a torque arm for itself, which is due to their design according to the invention with a corresponding sensor, suitable with a corresponding in the art known Karftschrauber together.

The torque support according to the invention for a device for the pneumatic or hydraulic drive of a shaft with a tool holder and a housing, at least with a portion of the housing of the device for receiving a reaction torque rotatably connected and has at least one sensor for determining a reaction torque, which is connected to a signal processing device. At least the torque arm and / or the shaft which can be accommodated in the torque arm form a reaction element which, during operation in the device, forms at least one tension line. The sensor detects during operation of the device in a region of the at least one voltage line, preferably in the region of the maximum voltage lines of the reaction element at least one change in length and determines by means of the signal processing means and predetermined parameters an action torque of the shaft in the tool holder.

In the combination, the device for pneumatic or hydraulic drive comprises a shaft with a tool holder, a housing, a torque arm, which at least with a portion of the housing for receiving a reaction torque and at least one sensor for determining a reaction torque, with a Signal processing device is connected. At least the torque arm and / or the shaft form a reaction element which has at least one tension line during operation. The sensor detects in a range of at least one voltage line, preferably in the range of the maximum voltage lines of the torque arm and / or shaft, i. a reaction element, during operation of the device at least one change in length and determined by means of the signal processing means and predetermined parameters, an action torque of the shaft in the tool holder.

In this case, a torque support according to the invention is understood to mean a component which absorbs the reaction force, for example when a screw is screwed in, by means of a shaft. For example, in one embodiment, such a component may be designed as a kind of reaction arm, e.g. laterally, preferably axially to the action shaft, arranged by the housing and rotatably connected with this. In another embodiment, it may be configured as a reaction sleeve, e.g. is arranged around the rotary shaft. This is based on the housing or a machine element (component for receiving the reaction force) and engages on the opposite side in a, connected to the element to be screwed structure frictionally. Such a structure may be, for example, a profiled washer, which projects beyond the screw head to be attracted and on the upper side of which the non-positive connection with the torque sleeve and on the other side a frictional connection with the element to be screwed is provided. Such systems are known in the art.

Such a torque arm has to absorb a considerable part of the reaction force, which is caused by the action torque of the shaft (same use under normal use). This results in a torsion of the shaft or the torque arm, and it forms in and on the shaft or torque arm tension lines. Length changes can be detected along these stress lines and detected by means of a suitable sensor. The length changes are a function of the reaction torque. In the simplest case, this function can be a proportional relationship between the reaction torque and the change in length.

In this case, a signal processor according to the invention is understood to be a controller or a similar computer which calculates from the measured values of the sensor or the sensors a nominal torque for the shaft with which the pneumatic or hydraulic drive is controlled.

A pneumatic or hydraulic drive according to the invention is understood to mean a pressure source, for example a hydraulic pump or a compressor. This pressure source can be controlled via a suitable interface. As a manipulated variable, for example, the desired torque of the shaft (action torque) is selected.

With a device according to the invention for direct measurement of the torque, therefore, a systematic measurement error caused by the back pressure in the indirect control according to the prior art is avoided. Furthermore, it is possible to work more precisely and with a higher back pressure - and thus faster - than with indirect control. Thus, a device according to the invention also achieves higher values in machine capability tests (MFU) according to FIG VDI / VDE Guideline 2645 Sheet 2 , A device according to the invention can also be used for screwing systems of safety category A according to VDI / VDE 2862 sheet 2 be allowed. A key message of the guideline is to classify only those screwdriving systems that have the direct measurement of angle of rotation and / or torque as suitable for screwdriving applications with a high risk assessment.

Especially with intermittently operating hydraulic tools, the advantages of the invention are particularly clear. Thus, with each ratcheting step, the stroke end of the tool is clearly recognized. The screws can therefore be tightened with greater precision, and thus safer.

In one embodiment of the invention, the torque arm is at least partially extending around the shaft support leg or reaction arm or in particular a sleeve. The aforementioned embodiments are non-rotatably connected to the housing of a shaft or the device and cooperate with another counter bearing in the region of a screw connection.

In one embodiment, the pressure source may be part of a tool that is indirectly controlled according to the prior art. In this case, a device according to the invention is placed on the shaft of the indirectly controlled tool and controlled by the signal processing means the pressure source (or the power supply). In this way, conventional machines can be used with relatively little effort - i. without the need to completely replace the tools - be brought to a higher standard of machine and process safety.

In one embodiment of the invention, the counter-bearing for the torque arm, if this is designed in the form of a sleeve, a profiled washer. This embodiment leads to a compact design of the device and moreover has the advantage that the corresponding component is relatively easy to manufacture.

In an embodiment according to the invention, the sensor for determining the torque is a strain gauge (DMS) or a measuring method which operates according to the physical principle of magnetostriction, such as e.g. a Pulsed Current Modulation Encoding (PCME) sensor.

A DMS provides an electrical chain size that is proportional to the change in length of the DMS. In particular, the strain gages are preferably arranged in the region of the torque arm so that their measuring range extends along the stress lines. This is preferably an extension direction which is substantially perpendicular to the axis of rotation of the shaft. An advantage of such an arrangement is that in this area relatively large changes in length can be determined and thus the measurement results are improved. Of course, this can also be deviated to some extent in order to possibly be able to take into account application-specific requirements such as robustness of the system during operation when positioning the strain gages. In addition, it may be advantageous to arrange the strain gages in the region of relatively thin sections of the torque arm and, if necessary, to use a large number of opposing strain gages (externally and internally) on the correspondingly designed torque arm.

A PCMC sensor is understood to mean a sensor which utilizes the so-called inverse magnetostrictive effect. In this case, a magnetic field changes when a force acts on a magnetically coded component. Such sensors are known in the art. In a device according to the invention, the torsion (as a function of the reaction torque) can be measured directly on the shaft with such a sensor.

In one embodiment of the invention, the signal processing device determines the reaction torque on the torque arm and / or the shaft by means of the sensor and thus controls the drive of the shaft.

The signal processing device may receive the measured quantities from one or more sensors. The sensors can be of the same type or use different measuring principles. According to the principle of operation and the design of the sensors, a plurality of sensors for detecting the reaction torque can be used, preferably at several different locations of the device. This has the advantage that a redundant measurement of the torque is possible. As a result, for example, a higher precision of the measurement can be achieved, or inconsistencies in the measurement - caused e.g. by the failure of a sensor or the breakage of a part of the device according to the invention - be detected. This leads to a further increase in the security of the systems.

In one embodiment according to the invention, at least one further sensor for determining a rotational angle of the shaft is provided in addition to the sensor for determining the torque. This is preferably selected from a group of sensors which comprises optical, inductive or resistive sensors, in particular axial rotation angle sensors, Hall sensors, combinations thereof and the like.

The angle of rotation is measured against a (basically arbitrary) fixed point next to the shaft. During initialization, the zero position is set.

Such an additional direct sensor leads to a further increase in the precision of the screwing operation. In addition, the redundancy is increased, which further improves the safety of the device. Thus, in a prior art power wrench, it is not recognized when e.g. the tool pawl is not working properly. An indirect measurement system would output an angle value that would not be transferred to the tool spindle if the system does not re-reference other physical parameters, but this can be erroneous. An independent idle sensor self-test, as required for a MFU, thus can not be performed correctly by the tightening system itself, as manipulation of the tool pawl or failure of the tool ratcheting system will not detect the wrong values. This has the consequence that an incorrectly operating ratchet system is not recognized in the tightening process and thus it can lead to unnoticed incorrectly tightened screw.

This also complies with the requirements for safety category A tightening systems VDI / VDE 2862 sheet 2 Fulfills.

• • Erfassung einer Längenänderung in einem Bereich wenigstens der Spannungslinie, vorzugsweise im Bereich der maximalen Spannungslinien eines Reaktionselementes, insbesondere der Drehmomentenstütze oder der Welle, mittels des Sensors, wobei die Längenänderung der Spannungslinie eine Funktion des Reaktions-Drehmoments ist;
• • Bestimmen eines Drehmoments der Welle im Bereich der Werkzeugaufnahme mittels der Signalverarbeitungseinrichtung und vorgegebenen Parametern;
• • Steuern der Energiezufuhr, als Funktion des Drehmoments der Welle.

An inventive method for driving a shaft with tool holder by means of hydraulic or pneumatic power supply comprises the following steps:

• Detecting a change in length in a region of at least the stress line, preferably in the area of the maximum stress lines of a reaction element, in particular the torque arm or the shaft, by means of the sensor, wherein the change in length of the stress line is a function of the reaction torque;
• Determining a torque of the shaft in the area of the tool holder by means of the signal processing device and predetermined parameters;
• • controlling the energy supply, as a function of the torque of the shaft.

The detected change in length in a region of at least one stress line can be measured at one point or at several points, with one type of sensor or with several types of sensors. If there was no damage, for example a break, between the shaft and the reaction element, the sensor (s) will receive correlated values. In the case of redundant sensors, differences in detection may be used as an indicator of an error - the sensor or the machine - and the machine may be stopped, for example, before damage to the tightening system occurs.

The signal processing device combines the detected values of the sensor or sensors with predetermined parameters, for example functions or tables, which reflect the dependence of the sensor values on a change in the reaction torque. After this combination and in conjunction with a control algorithm, the desired torque of the shaft (action torque) is determined by the signal processing device.

A machine operating according to a method of the invention may be further configured for self-test functionality.

This desired torque is used to control the power supply of the pressure source via a suitable interface, preferably industrial interfaces. For this purpose, preferably an analog current interface, an analog voltage interface or fast bus systems, such as e.g. a CAN bus or optical buses.

In a method according to the invention, the signal processing device is suitable for the intermittent control of the energy supply.

With such a design, the inventive method is particularly suitable for ratchet operation or for ratchet systems. While methods of the prior art are usually constructed in two stages or work slowly, this method allows a faster, more precise and fault-tolerant working.

In a method according to the invention, the signal processing device for intermittent control operates at frequencies of 0.1 to 15 pressure peaks or strokes per second, in particular up to 10 pressure peaks or strokes per second, which may differ in particular depending on the tool type.

With a system according to the invention several readjustment processes can be carried out, and thus high powers are possible with fast and precise load changes. This significantly increases the screwing performance, resulting in higher overall performance, improved efficiency and reduced machine downtime.

In a method according to the invention, the control device for controlling the power supply has a PID controller, wherein, depending on Requirement emphasis of the screwing also P-controller or PI-controller can be used.

Thus, even high demands on the control can be mastered, which are caused by the weight of the components involved, by flow resistance of the hydraulic or pneumatic system and by elastic deformation of the reactive parts.

Use of a device according to one of the preceding claims as a power wrench, in particular as a hydraulic power wrench, preferably for transmitting forces of over 1,000 Newton meters, more preferably between 1,000 and 20,000 Newton meters.

Power wrenches according to the present invention are used particularly in power plant construction, in the assembly of large installations and components, e.g. Installation and maintenance of large wind turbines used. The tool holder preferably has a hexagonal drive or square drive.

Further features of the invention will become apparent from the following detailed description of embodiments of the invention in conjunction with the drawings and the claims.

Showing:

1 : the sketch of a hydraulic tool according to the invention with an axially supported around the shaft reaction arm;

2 FIG. 2 is a sketch of a hydraulic tool according to the invention with a reaction arm device not axially arranged relative to the shaft; FIG.

3 : the sketch of a hydraulic tool according to the invention with a reaction sleeve;

4 : the sketch of a hydraulic tool according to the invention with a reaction sleeve with openings to the action wave;

5 : Schematic of a method for driving a shaft with tool holder according to the prior art;

6 : Scheme of a method for driving a shaft with tool holder in an embodiment according to the invention with detection of the torque;

7 : Scheme of a method for driving a shaft with tool holder in an embodiment according to the invention with detection of the torque and the angle of rotation.

1 shows the sketch of a power wrench according to the invention. This has a housing 1 on, at the bottom of a shaft 12 is arranged with a tool holder. About the hydraulic coupling 2 is the wave 12 via an internal piston ratchet mechanism, not shown, connected to a pressure source (eg to a hydraulic unit, not shown) for supply of hydraulic energy. Furthermore, on the housing 1 an axial around the shaft 12 supported reaction arm 5 arranged with a section of the housing 1 rotatably connected. The reaction arm 5 is to absorb the reaction torque - as a counterpart to the action torque of the shaft 12 - intended. The reaction arm 5 experiences under load, ie upon actuation of the shaft 12 , a twist and / or a stretch. When load is thus formed in and on the reaction arm 5 Voltage lines. On the reaction arm 5 , preferably in the range of maximum voltage lines, is a sensor 13 arranged. This sensor 13 - For example, a strain gauge - recorded in torsion and / or extension of the reaction arm 5 a change in length which is proportional to the reaction torque at the reaction arm 5 is. The sensor 13 is with a signal processing device 7 connected. This determines the desired torque of the shaft 12 in the area of the tool holder, based on the sensor 13 and predetermined parameters. The signal processing device 7 controls with this setpoint torque the pressure source.

2 shows the sketch of an alternative embodiment of the power wrench according to the invention 20 with a non-axial to the shaft 12 arranged Reaktionsarmvorrichtung. Here denote elements with the same reference numerals as in 1 the same elements.

The reaction arm 9 is arranged differently than at 1 ; Nevertheless, this also experiences under load - which by an action torque of the shaft 12 caused - a torsion and / or extension, which can be detected by means of one or more torque sensors. In the embodiment shown are to the signal processing device 7 three sensors connected: a torque sensor 10 , which is arranged in the tool housing, a torque sensor (not visible) on the back of the reaction arm 9 and a sensor 8th for detecting the angle of rotation of the, at the upper part of the housing 1 is arranged.

3 shows the sketch of a power wrench according to the invention 20 with a reaction sleeve 3 as a torque arm. Inside the reaction sleeve 3 is the inside wave 11 arranged (only partially visible). On the outside of the reaction sleeve 3 is a torque sensor 13 - For example DMS - arranged, the length changes due to the reaction torque of the reaction sleeve 3 detected. On the reaction sleeve 3 is another sensor system 4 arranged, which is designed here as a PCMC sensor. This PCMC sensor 4 directly measures the reaction torque on the shaft 11 , by means of the so-called inverse magnetostrictive effect. In this case, a magnetic field changes when a force acts on a magnetically coded component.

4 shows the sketch of another, alternatively designed power wrench according to the invention. This is similar in structure as in 3 shown. However, here is the torque sensor 13 in openings of the reaction sleeve 3 to the wave of action 11 arranged. Experiments show that in this embodiment, the easily determinable lines of force in the lower or in the upper region of the openings ie in this respect are out of center. In particular, it must be avoided by arranging that the DMS in the region of so-called neutral Lienien, since there no or only small changes in length can be determined.

5 shows a schematic of a method for driving a shaft 12 with tool holder according to the prior art, by means of indirect measurement. The energy supply of the shaft happens 12 via the hydraulic coupling 2 , The wave 12 applies an action torque to the tool or the tool holder. The signal processing device 7 Measures via a sensor between pressure source and hydraulic coupling 2 the hydraulic (or pneumatic) pressure of the power supply, which is generated for example by a hydraulic pump, and thus controls the pressure source. This measured pressure is used to calculate the desired torque value at the shaft 12 used.

6 shows a schematic of a method for driving a shaft 12 with tool holder in an embodiment according to the invention. As in 5 the energy supply of the wave happens 12 via the hydraulic coupling 2 , and the wave 12 applies an action torque to the tool or the tool holder. However, by means of direct measurement by one or more torque sensors 4 . 10 . 13 - The reaction torque to a torque arm 3 . 5 . 9 detected and to the signal processing device 7 transmitted. This controls the pressure source, here based on the reaction torque.

7 shows a schematic of a method for driving a shaft 12 with tool holder in a further embodiment of the invention. The detection of the reaction torque takes place as in 6 by direct measurement by one or more torque sensors 4 . 10 . 13 , In addition, by means of the rotation angle sensor 8th the angle of rotation of the shaft is detected. Here, the pressure source is controlled based on the reaction torque and the rotation angle.

LIST OF REFERENCE NUMBERS

1

casing

2

hydraulic clutch

3

reaction sleeve

4

Sensor system on reaction sleeve (PCMC sensor)

5

Reaction arm, axial to the action shaft

7

Signal processing device

8th

Rotation angle sensor

9

Reaction arm, not axial to the action shaft

10

Torque sensor in the tool housing

11

Inside action wave

12

Action wave, shaft with tool holder

13

Torque sensor (for example strain gauges)

20

power wrench

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• VDI / VDE guideline 2862 sheet 2 [0003]
• VDI / VDE Directive 2645 Part 2 [0018]
• VDI / VDE 2862 Part 2 [0018]
• VDI / VDE 2862 Part 2 [0031]

Claims (12)

Torque support ( 3 . 5 . 9 ) for a device ( 20 ) for the pneumatic or hydraulic drive of a shaft ( 11 . 12 ) with a tool holder and a housing ( 1 ), wherein the torque arm is rotatably connected to at least a portion of the housing for receiving a reaction torque and at least one sensor ( 4 . 10 . 13 ) for determining a reaction torque, which is provided with a signal processing device ( 7 ), wherein at least the torque support ( 3 . 5 . 9 ) and / or the shaft which can be accommodated in the torque arm forms a reaction element which during operation of the device ( 20 ) forms at least one voltage line, characterized in that the sensor ( 4 . 10 . 13 ) during operation of the device ( 20 ) in a region of the at least one stress line, preferably in the region of the maximum stress lines of the reaction element ( 3 . 5 . 9 ) detects at least one change in length and by means of the signal processing device ( 7 ) and given parameters an action torque of the shaft ( 11 . 12 ) determined in the tool holder. Contraption ( 20 ) for the pneumatic or hydraulic drive of a shaft ( 11 . 12 ) with a tool holder, a housing ( 1 ), a torque arm ( 3 . 5 . 9 ), which at least with a portion of the housing for receiving a reaction torque and at least one sensor ( 4 . 10 . 13 ) for determining a reaction torque, which is connected to a signal processing device ( 7 ), wherein at least the torque support ( 3 . 5 . 9 ) and / or the wave ( 11 . 12 ) form a reaction element which has at least one stress line in operation, characterized in that the sensor ( 4 . 10 . 13 ) in a region of the at least one stress line, preferably in the region of the maximum stress lines of the torque support ( 3 . 5 . 9 ) and / or wave ( 11 . 12 ), during operation of the device ( 20 ) detects at least one change in length and by means of the signal processing device ( 7 ) and given parameters an action torque of the shaft ( 11 . 12 ) determined in the tool holder. Apparatus according to claim 1 or 2, characterized in that the torque arm comprises a supporting foot (FIG. 5 ) or reaction arm ( 9 ) or in particular a sleeve ( 3 ), which is rotationally fixed to the housing of the shaft or a drive shaft ( 11 . 12 ) are connected and cooperate with another abutment in the region of a screw. Apparatus according to claim 2, characterized in that the abutment for the torque arm in the form of a sleeve is a profiled washer. Device according to one of the preceding claims, characterized in that the sensor ( 4 . 10 . 13 ) is a strain gauge or a magnetostriction sensor, in particular a PCMC sensor for determining the torque. Device according to one of the preceding claims, characterized in that the signal processing device ( 7 ) the reaction torque at the torque arm ( 3 . 5 . 9 ) and / or the wave ( 11 . 12 ) by means of the sensor ( 4 . 10 . 13 ) and thus the drive of the shaft ( 11 . 12 ) controls. Device according to one of the preceding claims, characterized in that next to the sensor ( 4 . 10 . 13 ) for determining the torque at least one further sensor ( 8th ) for determining a rotation angle of the shaft ( 11 . 12 ) is provided and this is preferably selected from the group of sensors, which includes optical, inductive or resistive sensors, in particular axial rotation angle sensors, Hall sensors, combinations thereof and the like. Method according to claim 1 or 2 for driving a shaft ( 11 . 12 ) with tool holder by means of hydraulic or pneumatic energy supply ( 2 ), comprising the steps of: detecting a change in length in a region of at least the stress line, preferably in the region of the maximum stress lines of the torque support ( 5 . 9 ) by means of the sensor ( 4 . 10 . 13 ), wherein the change in length of the stress line is a function of the reaction torque, - determining a torque of the shaft ( 11 . 12 ) in the region of the tool holder by means of the signal processing device ( 7 ) and given parameters, - controlling the energy supply ( 2 ), as a function of the torque of the shaft ( 11 . 12 ). Method according to Claim 8, characterized in that the signal processing device ( 7 ) is suitable for the intermittent control of the power supply. Method according to claim 9, characterized in that the signal processing device ( 7 ) for intermittent control at frequencies of 0.1 to 15 pressure peaks or strokes per second, in particular up to 10 pressure peaks or strokes per second works. Method according to one of claims 8 to 10, characterized in that the control device ( 7 ) for controlling the energy supply ( 2 ) has at least one P-controller, PI controller or PID controller. Use of a device ( 20 ) according to one of the preceding claims as a power wrench, in particular as a hydraulic power wrench, preferably for transmitting forces of over 1,000 Newton meters, more preferably between 5,000 and 20,000 Newton meters.

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