EP3829817B1 - Screwing device, driving torque generating means, screwing system and torque control method - Google Patents

Description

The present invention relates to a screwing device for applying a torque to a screwing partner. In addition, the invention relates to a drive torque generating means for generating a torque. Furthermore, the present invention relates to a screwing system, at least comprising a screwing device and a drive torque generating means. Furthermore, the present invention relates to a method for controlling the drive motor of a screwing system. In addition, the invention relates to the use of a screwing system for carrying out the method. The document WO 2018/188829 A1 shows a device or a system according to the preambles of claims 1, 3 and 6.

Screwing devices are known from practice, in particular from industrial screwing technology, which are referred to, for example, as so-called offset drives and in particular for screwing or assembly work in which the screwing partner (i.e. for example a screw to which a torque is to be applied within the context of the present invention) can only be reached with difficulty or with great effort due to special spatial installation conditions. Flat drives are usually gear units accommodated in a flat housing with a drive usually provided at one end and an output drive provided at the opposite end, on which the screwing partner can then be attached in a suitable detachable manner. The gearbox in the offset output housing often consists of an intermeshing arrangement of gears that meshes and thus transmits torque from the input to the output. however, depending on the area of application, there are different variations and Modifications of this technology, which is generally known and assumed to be generic, are possible and known.

On the output side, offset outputs have an output gear wheel, which is supported by at least one adjacent gear wheel and can be designed to mesh with it. The output gear serves to transmit the torque to the screwing partner. In this regard, a distinction must be made between a closed design, in which the screwing partner can only be inserted axially into the output gear, which is provided with a hexagon socket, for example, and an open design, in which the screwing partner also engages with the output gear radially in relation to the axis of rotation of the output gear can come.

In the case of the open design, the output gear wheel is not closed, but has a recess on its circumference in order to be able to accommodate the screw partner in the hexagon socket in the radial direction. In order to be able to adequately support the output gear in each phase of its rotation, the output gear meshes at times with at least two adjacent gears or support gears, so that the output gear is driven by at least one of the two support gears. During a complete rotation of 360°, the output gear wheel thus passes through at least one full support phase, in which it is in mesh with at least two other gears or support gears, and at least one partial support phase, in which fewer gears or support gears mesh than in the full support phase. Usually, the output gear meshes with two support gears in the full support phase and one support gear in the partial support phase. In the partial support phase, the recess of the output gear thus faces that support gear which the output gear just does not mesh with.

In the case of the closed design, an adjacent gear wheel is usually sufficient for support and torque transmission, so that the output gear wheel of the closed design only runs through a full support phase during a complete rotation of 360°.

The screwing device just described is mostly used in conjunction with a drive torque generation means, which can be designed to generate a torque and to interact with a screwing device. The driving torque generating means can be, for example, a hand-held tool or a straight or straight-angle screwdriver. Such drive torque generation means are mostly used in an industrial context and used in particular in combination with a screwing device to create a satisfactory assembly in special spatial installation conditions in which screwing partners are difficult to reach.

The combination of the screwing device and the drive torque generating means can be summarized as a screwing system, it being possible for the two parts to be combined with one another across manufacturers. For example, manufacturers of screwing devices are known which do not sell drive torque generating means and vice versa.

Bolting systems with a drive torque generation means and in particular the drive torque generation means comprise a drive motor and possibly a control or regulating unit for the drive motor. This control unit determines, for example, whether the tool is operated either in torque control or in speed control. In speed control, for example, a speed to be maintained and a cut-off torque are specified fixed. The controller then adjusts the torque output by the drive motor accordingly. However, such a relationship completely disregards inaccuracies, sluggishness and efficiency losses of a driven screwing device. An overall efficiency is known, but not the influence of the screwing device on the overall efficiency.

The meshing of the at least one adjacent supporting gear wheel has an effect, for example, on a screwing device of the open as well as the closed type, a gear crack, a concentricity error, a toothing error (e.g. damage to the tooth flank), lubrication, a surface quality and/or a state of friction between contacting ones Tooth flanks have a negative effect on the efficiency of the screwing device and thus also of the screwing system. The greater these influences are, the more fluctuating is the efficiency. In this sense, fluctuating means that an efficiency curve shows significant deflections compared to a harmonic efficiency curve.

Due to the design-related phases of a different number of meshed support gears in an open offset output, there is also a measurable sluggishness of the offset output. This leads to strong fluctuations in the operating behavior of the motor of the drive torque generating means, since it tries to compensate for the sluggishness that occurs. When operating in speed control mode (a speed is specified, the motor readjusts the torque), the motor tries to be able to comply with the speed specification, for example by changing the output torque. This uneven and inharmonious torque curve results in poor efficiency of the Bolting system for the partial support phases compared to the efficiency of the full support phases. In summary, there is also an overall poorer degree of efficiency if one compares the design of the open offset offset with the design of the closed offset offset.

The strong torque variation over one revolution of the output gear wheel also means that, for a given cut-off torque, the output torque of the motor can pass the cut-off torque and the motor can therefore be switched off. However, the switch-off can be caused by the above-mentioned influences of the geared offset drive that degrade the efficiency and not, as desired, by a tightened screw partner. So it can happen that a screw connection is not tightened up to the desired tightening torque because the motor switches off prematurely. In the worst case, however, a screwing partner that has been tightened as desired is accepted by a user, which can lead to damage and/or considerable safety risks if the screwing partner suddenly loosens.

The unevenness in the torque curve means that individual outliers in the torque curve can exceed a defined switch-off limit, which means that the drive motor is switched off before the desired limit torque of the screw connection is reached. In other words, in the case of screwing devices and in particular open offset drives, the short-term passing of the switch-off limit due to the partial support phase leads to the motor being switched off, although it is not even known what tightening torque is actually transmitted to the screwing partner, which leads to an undefined tightened screw connection.

There is therefore a particular technical need to solve the common problem for each of the three aspects (screw device, drive torque generating means and screw system).

The problem that all three aspects (screwing device, drive torque generating means and screwing system) have can be seen in the fact that efficiency-deteriorating influences have a direct impact on motor behavior and thus uniform operating behavior and defined tightening of a screwing partner is difficult or impossible. Particularly when using open geared offset drives, the partial support phase-related brief passage of the cut-off torque through the output torque can lead to the motor switching off prematurely and thus to an undefined tightened or unfinished screw connection.

However, it is often necessary, especially in an industrial context, to produce a high-quality screw connection for quality assurance reasons.

The object of the present invention is therefore to propose a screwing device, a driving torque generating means, a screwing system, a method and a use which ensure a high-quality screwing, particularly with regard to the design of the screwing device. Furthermore, a screw connection should be able to be designed in such a way that it can be tightened up to a defined limit torque.

This object is achieved by the screwing device with the features of patent claim 1, by the drive torque generating means with the features of patent claim 3, by the screwing system with the features of patent claim 7, by the method for Drive motor control with the features of patent claim 10 and through use with the features of patent claim 16.

The invention is based on the knowledge that the aforementioned influences that degrade the degree of efficiency and/or the sluggishness occur cyclically with respect to the full 360° rotation of the output gear wheel. Considerable influences occur during the partial support phase, particularly in the case of an open-type geared offset drive. It was therefore known in which angular position of the driven gear what degree of efficiency is present and which influences have a detrimental effect. Manipulation or compensation of a value of the actual output torque output by the drive motor is provided to ensure uniform operating behavior and/or to prevent the drive motor from being switched off by prematurely reaching a defined limit value, such as the switch-off torque. Compensation data are used for this purpose, which can include a torque curve and/or an efficiency curve, such as are formed during a full 360° rotation of the output gear wheel and/or its passage through the full support phase and partial support phase. The information on the torque behavior or the efficiency of the screwing device can thus be used.

A compensation file or the torque curve specific to the output gear wheel, or more precisely its value, can be created, for example, by initially measuring the screwing device on a suitable test stand. With the knowledge of the point in time and/or the angle of rotation of the sluggishness, the value of the actual output torque can now be manipulated or a peak in the recorded actual output torque that may exceed the value of the cut-off torque can be compensated take place. Because it is now known at what point in time and/or at what angle of rotation sluggishness occurs, the torque peak caused by the output gear wheel and/or its proportion of the torque peak can be calculated from the value of the actual output torque output by the drive motor.

The torque curve specific to the output gear can include, for example, data or values for a full 360° revolution of the output gear or only for at least one angle window or a partial support phase.

This can achieve several advantages. On the one hand, a considerable improvement in efficiency can be brought about. On the other hand, when comparing with the at least one compensation file, it can now be seen whether the torque peak is caused by the driven gear wheel or by a screw connection. In the event that the value of the compensated torque exceeds a limit value, such as the cut-off torque, it is assumed that there is a tight screw connection. The invention only compensates for the increase in torque caused by the driven gear wheel, so that when the limit value is reached due to screwing, the motor can be switched off, as is known.

This basic idea according to the invention is embodied in the screwing device according to claim 1, in the driving torque generating means according to claim 3, in the screwing system according to claim 7, and is realized with the method according to claim 10 and the use according to claim 16.

To solve the above-mentioned problems, a screwing device is therefore proposed for applying and/or transmitting a torque to a screwing partner and for interacting with a means for generating drive torque, comprising flat output means which have an output which can be detachably connected to the screwing partner and a drive which can be acted upon manually or mechanically with a drive torque have a driven gear, which can be driven by the flat output means, a mechanical interface, for optional direct or indirect connection to the drive torque generating means for introducing the torque, a compensation unit, designed to store and process compensation data, comprising a driven gear-specific torque curve and/or a driven gear-specific Efficiency curve, for offsetting with a value of an actual output torque to generate a value of a compensated output torque, and a data interface, designed to transmit compensation data to a drive torque generating means.

The screw device can have an open design, for example. During a complete rotation, the driven gear wheel passes through at least one full support phase, in which it meshes with at least two other gears, and at least one partial support phase, in which fewer gears mesh than in the full support phase. However, the screwing device can also have a closed design, for example. The screwing device can also be an angle head. An angle head can be arranged between a drive torque generating means and a geared offset head to transmit torque via a power transmission gear. The invention can consequently also be implemented in an angle head, with the flywheel drive means also in an angle head can be referred to as gears or bevel gears for transmitting a torque and the output gear can be referred to as that gear which transmits the torque from the angle head, for example to a flywheel.

The screwing device can be connected in a known manner to various suitable drive torque generating means and has at least one own compensation file in order to make it available to the drive torque generating means via the data interface. "Calculation" in the sense of the invention does not directly mean the use of basic arithmetic operations, but rather computer-aided processing.

In a preferred embodiment of the screwing device according to the invention, at least one torque detection means is provided for detecting the value of the actual output torque. Usually, screwing devices and in particular geared offset drives do not have their own torque detection means. The torque detection means of the screwing device can be a torque sensor. Since screwing devices for screwing are used in combination with a drive torque generation means and the drive torque generation means usually includes its own torque detection means, a torque detection means in a screwing device can in principle be dispensed with. However, such a torque detection means offers the possibility of torque detection in the screwing device itself, so that these data provide precise information about the torque actually present at the output gear wheel or at least provide a clear indication of it.

According to the invention, a drive torque generating means for generating a torque and for interacting with a screwing device is also proposed, comprising a drive motor, a mechanical interface designed for optional direct or indirect connection to the screwing device for introducing the torque, a torque detection means for detecting a value of the actual output torque, and a compensation unit, designed to store and process compensation data, comprising a torque profile specific to the output gear and/or an efficiency profile specific to the output gear, for offsetting against the value of an actual output torque to generate a value of a compensated output torque.

The basic idea according to the invention can also be implemented in a drive torque generating means. By detecting the torque using the torque detection means, the position of the driven gear wheel can be identified at any time by means of a comparison with the compensation data. As a result, a compensation according to the invention can be carried out at least in the partial support phase. The torque detection means can be a torque sensor, for example, or else a motor encoder.

The drive torque generating means can be connected in a known manner to various suitable screwing devices and can store compensation data for the connected screwing device.

In the drive torque generating means according to the invention, a data interface is provided for the transmission of Compensation data is formed. As a result, for example, data can be exchanged between the means for generating drive torque and a screwing device connected to it. It is conceivable, for example, that a single drive torque generation means can carry out compensations according to the invention in a manner according to the invention for each torque of different screw devices that can be connected to the drive torque generation means. Thus, one driving torque generating means can be used for various screwing devices. The data can be transmittable wirelessly or by cable, for example.

It is alternatively or additionally conceivable that a screw device identification means is provided. Such a means is suitable for clearly identifying the screwing device connected to the drive torque generating means. The identification can take place, for example, via manual input to the drive torque generating means or also automatically when a screwing device is connected. The screwing device can preferably transmit its own identification to the drive torque generating means by means of the data interface. A specific compensation file can be assigned to each identification, which can be called up and used when the identification is recognized. The compensation unit can, for example, store a large number of output gear-specific torque curves or efficiency curves in order to interact with the corresponding different screwing devices in a manner according to the invention.

According to a further preferred embodiment of the invention, the screw device or the Drive torque generating means provided an angle determining means for determining a position angle of the output gear. By means of such an angle determination means, the position of the driven gear or its position angle can be precisely detected, for example in a 360° system, and it can thus be determined in which phase the driven gear is located. In this case, it can also be advantageous to identify the screwing device and in particular its transmission ratio. In addition, a zero position (0°) or an angular distance from it does not have to be initially specified, since it can be determined.

A screwing system is also proposed, at least comprising a screwing device, comprising flat output means which have an output which can be detachably connected to the screwing partner and a drive which can be subjected to a drive torque manually or mechanically, an output gear wheel which can be driven by the flat output means, a mechanical interface, for optional direct or indirect connection to the torque generating means for introducing the torque,
as well as a drive torque generation means, which is connected to the flat output means on the drive side, comprising a drive motor, a mechanical interface, designed for optional direct or indirect connection to the screwing device for introducing the torque, a torque detection means for detecting a value of the actual output torque, and a compensation unit, designed for storing and processing compensation data, comprising a torque profile specific to the output gear and/or an efficiency profile specific to the output gear, for offsetting against the value of the actual output torque to produce a compensated output torque value.

The screwing system can be designed as a hand-held screwing system and then has such a weight that it can preferably be carried by an operator with one hand. In terms of weight, it is therefore within the framework of legal requirements. However, it can also be designed as a stationary system.

According to a preferred embodiment of the screwing system according to the invention, this comprises at least one data interface designed to transmit compensation data. By means of such a data interface, data can be sent either between the screwing device and the means for generating drive torque or between the screwing system and an external data point. It is conceivable, for example, to carry out maintenance work on the compensation data or to adapt compensation data.

According to a further preferred embodiment of the screwing system according to the invention, this includes an angle determination means for determining a position angle of the output gear.

• Ablegen eines abtriebszahnradspezifischen Drehmomentverlaufs und/oder eines abtriebszahnradspezifischen Wirkungsgradverlaufs in einer Kompensationseinheit,
• Erfassen eines Wertes des von dem Antriebsmotor ausgegebenen tatsächlichen Abtriebsdrehmoments mittels eines Drehmomenterfassungsmittels,
• Verrechnen des Wertes des tatsächlichen Abtriebsdrehmoments mit zumindest einer Kompensationsdatei zur Erzeugung eines Wertes eines kompensierten Abtriebsdrehmoments, und
• Ausgeben durch die Kompensationseinheit des Wertes des kompensierten Abtriebsdrehmoments an eine Regeleinheit des Antriebsmotors.

According to the invention, a method for controlling the drive motor of a screwing system, preferably a screwing system according to claim 7, is also proposed, comprising at least the following steps:

• Filing a driven gear-specific torque curve and/or a output gear-specific efficiency profile in a compensation unit,
• detecting a value of the actual output torque output by the drive motor using a torque detecting means,
• calculating the value of the actual output torque with at least one compensation file to generate a value of a compensated output torque, and
• The value of the compensated output torque is output by the compensation unit to a control unit of the drive motor.

The method thus realizes the basic idea of the invention. The torque profile specific to the output gear and the efficiency profile specific to the output gear are compensation files. The method according to the invention essentially has the advantages mentioned above, to which reference is hereby made.

In a preferred embodiment of the method according to the invention, the calculation includes comparing and/or subtracting and/or adding a compensation file with the value of the actual output torque, preferably exclusively for at least one partial support phase and/or smoothing the value of the actual output torque, preferably exclusively for at least a partial support phase. As a result, the increase in torque caused by the screwing device can be manipulated in such a way that it can be represented as non-existent. The to the control unit, which, for example, for control and / or Control processes can be formed, output value of the compensated output torque is processed there and processed in a known manner depending on the operating mode (speed control or torque control).

• Ermitteln mittels eines Winkelermittlungsmittels den Stellungswinkel des Abtriebszahnrades, und
• Verwenden des Stellungswinkels durch die Kompensationseinheit zur Erzeugung des Wertes des kompensierten Abtriebsdrehmoments.

According to a preferred embodiment of the method according to the invention, this comprises

• determining the position angle of the driven gear wheel by means of an angle determining means, and
• using the position angle by the compensation unit to generate the compensated output torque value.

In such an embodiment, the position angle of the output gear can be used for more accurate compensation. By means of this angle, for example, in the case of an open screw device, it can be seen at which rotational phases the output gear wheel is in the full support phase or in the partial support phase. The position angle can be specified in a 360° system. Typically, in an output gear supported by two support gears, a first partial support phase in a first angular window between about the 130th position angle and the 170th position angle and a second partial support phase in a first angular window between about the 190th position angle and the 230th position angle lay. However, the angle windows are dependent on the specific design of the support gears and their arrangement. With a zero position or a position angle of 0° of the output gear, there is an attachment position in an open screwdriving device, in which the output gear can be attached to a screwing partner.

• Vorgeben eines Abschaltdrehmomentwertes, bei dessen Erreichen durch den Wert des kompensierten Abtriebsdrehmoments der Antriebsmotor abgeschaltet wird, und
• Vorgeben einer Solldrehzahl, mit welcher der Motor dreht, wobei die Solldrehzahl dynamisch derart anpassbar ist, dass sie bis zum Erreichen des Abschaltdrehmomentwerts möglichst groß gewählt wird.

According to a further preferred embodiment of the method according to the invention, this comprises

• Specification of a switch-off torque value, which when reached by the value of the compensated output torque, the drive motor is switched off, and
• Specification of a target speed at which the motor rotates, the target speed being dynamically adaptable in such a way that it is selected as large as possible until the cut-off torque value is reached.

During operation, the setpoint speed can ideally be selected so high that the cut-off torque value is not exceeded. Such an embodiment leads to a fast screwing process.

It is also conceivable that the method according to the invention provides for the screwing system to be operated with speed control. Such a mode of operation is customary in particular in an industrial context and advantageously enables the invention to be used there.

• Zusammenfassen mehrerer Teilstützphasen innerhalb einer vollen Umdrehung des Abtriebszahnrades zu einer Teilstützphasengruppe, und
• Verrechnen des Wertes des tatsächlichen Abtriebsdrehmoments mit zumindest einer Kompensationsdatei zur Erzeugung eines Wertes eines kompensierten Abtriebsdrehmoments zumindest für die Teilstützphasengruppe.

According to another preferred embodiment of the invention, the method provides the steps:

• Combining several partial support phases within a full revolution of the output gear into a partial support phase group, and
• Calculating the value of the actual output torque with at least one Compensation file for generating a value of a compensated output torque at least for the partial support phase group.

In the event that the driven gear wheel passes through several partial support phases during a full rotation of 360°, several, preferably all, these partial support phases can be combined into a partial support phase group. The advantage is that only a single compensation per revolution has to be carried out, namely for the area of the partial support phase group, which extends from the first partial support phase of the group to the last partial support phase.

For example, if there are two partial support phases (e.g. first partial support phase in a first angle window between about the 130th position angle and the 170th position angle and second partial support phase in a first angle window between about the 190th position angle and the 230th position angle), one Part support phase group are formed, which ranges from the 130th position angle to the 230th position angle. A single compensation would therefore be made for this angular window.

A use of a screwing system according to claim 7 for carrying out the method according to claim 10 is also proposed. The use according to the invention essentially has the above-mentioned advantages, to which reference is hereby made.

Further advantages, features and details of the invention result from the following description of a preferred exemplary embodiment and from the drawings.

Fig. 1:

eine perspektivische Ansicht des erfindungsgemäßen handgehaltenen Verschraubsystems;

Fig. 2:

eine schematische Draufsicht (bei abgenommenem Gehäuse) auf die erfindungsgemäßen Flachabtriebsmittel;

Fig. 3:

ein Blockschaltbild von Komponenten des erfindungsgemäßen Verschraubsystems;

Fig. 4:

ein Protokoll eines Drehmomentverlaufs eines offenen Flachabtriebs;

Fig. 5:

ein Protokoll eines Wirkungsgradverlaufs des offenen Flachabtriebs gemäß Fig. 4;

Fig. 6:

ein Protokoll eines Drehmomentverlaufs eines geschlossenen Flachabtriebs;

Fig. 7:

ein Protokoll eines Wirkungsgradverlaufs des geschlossenen Flachabtriebs gemäß Fig. 6;

Fig. 8:

ein Diagramm zur Kompensation in einer Teilstützphase eines offenen Flachabtriebs; und

Fig. 9:

ein Diagramm zur Kompensation einer Teilstützphasengruppe eines offenen Flachabtriebs.

The drawings show in:

Figure 1:

a perspective view of the hand-held screwing system according to the invention;

Figure 2:

a schematic plan view (with the housing removed) of the flat output means according to the invention;

Figure 3:

a block diagram of components of the screwing system according to the invention;

Figure 4:

a log of a torque curve of an open offset gear;

Figure 5:

a protocol of an efficiency curve of the open offset gear according to 4 ;

Figure 6:

a log of a torque curve of a closed offset gear;

Figure 7:

a protocol of an efficiency curve of the closed offset gear according to 6 ;

Figure 8:

a diagram for compensation in a partial support phase of an open offset gear; and

Figure 9:

a diagram for the compensation of a partial support phase group of an open geared offset drive.

The 1 , System and context representation for the present invention, shows a perspective view of a hand-held screwing system with a screwing device 2 for applying a torque to a screwing partner, not shown, having flat output means 6 accommodated in a housing 4 of an open flat output 32. The flat output means 6 are at one end (Output side) designed to interact and to drive a suitable and designed as a slotted output gear 8 screwing tool. On the input side, i.e. at the end of the flat output means 6 opposite the output, these are connected via a mechanical interface 46 via an angle head 10 having a pair of gears or possibly bevel gears to a manually actuable drive torque generating means designed as a screwing tool 12.

The screwing tool 12 has a drive motor 26 (eg electric or pneumatic) and transmits the output torque it generates into the screwing device 2 . Both the screwing device 2 and the screwing tool 12 each have a mechanical interface for either direct or indirect connection Connection to the other of the two partners of the screwing system.

In a typical implementation for manual screw actuation, such screw devices 2 or flat output means 6 are provided and suitable for transmitting a maximum torque of approximately 250 Nm.

Screwing device 2 is designed as an open flat output and is characterized in that the output gear wheel 8 has a recess 62 designed as a slot for radially receiving a screwing partner in a hexagon socket. The screw device shown in the figures can also be designed as a closed geared offset drive. Both designs have identical influences that reduce the degree of efficiency, as mentioned at the outset, the effects of which are equally excluded for both designs by means of the invention. In addition, the open design also has an influence on the efficiency during the partial support phase, the effects of which can also be ruled out according to the invention.

2 shows several flat output means 6 or gears of the screwing device 2 in a plan view with the housing 4 removed, as well as an output gear 8 on the output side Support gear 20. The two support gears 18 and 20 transmit the torque to the output gear 8 through their respective meshing.

The gears 8, 14, 16, 18 and 20 are mounted axially parallel to one another and linearly along a longitudinal extension of the housing 4 in this rotatably mounted. A tightening direction of rotation 48 of the output gear wheel 8 is indicated by means of an arrow.

The output gear 8 runs through two full support phases and two partial support phases during a full rotation of 360°. In the full support phase, the output gear 8 is in engagement with both support gears 18 and 20 . In the partial support phases, the output gear 8 is only in engagement with one of the two support gears 18, 20. Expressed in angular positions, where 0° in the longitudinal direction of the housing 4 points towards an attachment position and can be referred to as the zero position, in which the output gear 8 can be attached to a screw partner, this means that a first full support phase begins at an angular position of 230°, an angular position of 0° and reaches an angular position of 130°. The first partial support phase begins at an angle of 130° and extends to an angle of 170°. This is followed by a narrow second full support phase between an angular position of 170° and 190°. Finally, the driven gear wheel 8 runs through a second partial support phase between an angular position of 190° and 230°. Thus, the full support phases and partial support phases alternate.

During each of the two partial support phases, sluggishness occurs, which leads to reduced efficiency, as shown in figure 5 shown. Stiffness can also occur in the narrow full support phase.

In 3 is now given an overview of various means and elements of the screwing system according to the invention and adjacent systems.

The screwing tool 12 includes a start button 22 for operating the screwing tool 12 by an operator. An energy supply and also a control unit 24 are activated by means of the start button 22 . When the screwing system is operated in speed control, a speed is specified and the control unit 24 readjusts, among other things, a torque output by the drive motor 26 by means of signals output to a drive motor 26 . For this purpose, the drive motor 26 can include, for example, a planetary gear, not shown. The drive motor 26 can in turn transmit its position and/or its angle of rotation to the control unit 24 by means of signals. The drive motor 26 outputs an actual output torque, which is detected as a value by a torque sensor 28 serving as torque detection means.

At this point, a control loop for the drive motor control of the screwing system begins. The torque sensor 28 transmits the actual output torque detected and output by the drive motor 26 or its value to a compensation unit 30. A torque profile specific to the output gear or an efficiency profile specific to the output gear is stored in the compensation unit 30. The compensation unit 30 is designed, among other things, to offset the value of the actual output torque with the output gear-specific torque curve in order to generate a value of a compensated output torque. In other words, the output gear-caused binding, which is peaked in the value of the output torque actually output, is removed or compensated for. The value of the compensated output torque is then transmitted from the compensation unit 30 to the control unit 24 . The control unit 24 is for comparing the value of the compensated Output torque formed with a cut-off torque, when it is reached by the value of the compensated output torque, the drive motor 26 is switched off.

With the invention it is now recognizable and ensured that when the drive motor 26 is switched off when the switch-off torque is reached, a screw connection has also been carried out to a successful end, ie to a fixed or defined screw connection. A premature shutdown, caused by the sluggishness of the screwing device 2 and the resulting increase in torque, possibly to above the shutdown torque, is now ruled out.

Moreover, the control unit 24 processes the value of the compensated output torque and torque in the same known manner as a value of an actual output torque in a known control loop of an engine control system.

The torque output by the drive motor 26 is output to the screwing device 2 via the mechanical interface. The screwing device 2 comprises in 3 shown embodiment the angle head 10 and the gear 6 comprehensive gear output 32, which also includes the output gear 8. The torque is finally transmitted from the output gear 8 to the screwing partner 50 to produce a tight screw connection.

The drive torque generation means or the screwing device 2 can comprise a screwing device identification means 34, which provides an identification of, for example, the design, the offset drive means 6, the offset drive 32 and/or the gear ratio can transmit to the screwing tool 12 by cable or wirelessly. A data interface 36 can be used for this purpose, for example in order to transmit compensation data. The screwing device 2 can also include a data interface 36 in order to receive, for example, compensation data from the screwing device 2 and/or to receive data from an external data source or to send it to this. The screwing device 2 can, for example, comprise an angle determination means 40 for determining a position angle of the output gear wheel 8 . This measured angular position value can be transmitted, for example, using one or both of the data interfaces 36 and 38 . This is indicated by an idealized data path 64, which transmits the measured angular position value from the angle head 10 and/or the angle determination means 40 to the control unit 24 for further processing.

An illustrative example of calibration is shown within a system boundary 42 . For this purpose, a screwing device 2 is connected in combination with a screwing tool 12 or a drive torque generating means and at least one full revolution of the output gear wheel 8 is recorded, as the display case 52 shows. The focus here is on the transmitted torque and efficiency. Preferably, for example, more than 50 full revolutions or screwing cycles can be recorded, as the showcase 54 shows. The resulting measurement signal of the torque is in 6 shown. This measurement signal is further processed in a manner not described further in display case 56 and possibly digitized. It is then transmitted via an interface 58 for data transmission to the compensation unit 30, for example, and stored there. However, this measurement signal can also be stored in a suitable memory of the screwing device 2 .

4 shows the measurement curve recorded within the system boundary 42 of an open offset gear with an output gear 8 meshed with two support gears 18 and 20. The synopsis of the Figures 4 and 5 shows the finding on which the invention is based. It was found that the tightness of the screwing device 2 occurs cyclically. The drive motor 26 attempts to compensate for this sluggishness, for example in the case of speed control, by increasing the output torque output, the peaks in 4 show. This results in the in figure 5 efficiency curve shown, which drops significantly every 360°. The drop in efficiency and the sluggishness coincide in time, so that the conclusion is that a change in the value should mean that a drive motor 26 does not have to react to sluggishness with an increased output torque output, which ultimately leads to improved efficiency.

6 shows the measurement curve recorded within the system boundary 42 of a closed offset gear with an output gear meshed by only one support gear. 7 shows the resulting efficiency curve. Opposite the in figure 5 shown measurement curves of the open offset gear, this measurement curve shows a more constant progression. Averaging the course of efficiency shows a sinusoidal wave 60 with cyclic behavior. In this case, the wave repeats itself every 360° with each revolution of the output gear.

Compensation examples and two options for drive motor controls are in the 8 and 9 shown. Although the following description only refers to the open offset offset, the principles mentioned can also be used with the closed offset offset.

In 8 a torque in Newton meters is plotted against an angle of rotation in degrees in a schematically simplified manner. The value of a cut-off torque is represented by a rough dashed line. The value of the output torque actually output is represented by a medium broken line. The value of the output gear-specific torque profile as a compensation file is shown using a fine dashed line. The value of the compensated output torque is represented by a solid line.

It can be seen that between an angular position of 130 ° and 170 ° of the output gear 8, the drive motor 26 tries to compensate for a sluggishness by outputting an increased output torque - the 6 torque peak shown. At least for this partial support phase between 130° and 170°, the compensation unit 30 offsets the value of the output torque actually output with the value of the torque specific to the output gear wheel. When compared with the value of the output gear-specific torque, the compensation unit 30 recognizes that a cyclic torque peak occurs in this angle window (130° to 170°)—a clear indication of a torque peak caused by the output gear. The result of this calculation is the value of a compensated output torque shown schematically. This output torque increases regardless of the compensation according to the invention and reaches the cut-off torque at point 44 . At this point 44, the control unit 24 causes the drive motor 26 to be switched off. It is assumed that a screw connection is tight at this point in time.

The 9 largely resembles that 8 , which is why only the differences will be discussed below.

It can be seen that the drive gear wheel 8 has both a first partial support phase between an angle of rotation of 130° and 170° and a second partial support phase between an angle of rotation of 190° and 230°. Between the two partial support phases there is a full support phase in an angle window of 170° to 190°. The two partial support phases are flanked by another full support phase, which ranges from a rotation angle of 230° to the zero position of 0° and a rotation angle of 130°. The two torque peaks in the partial support phases can now be compensated separately for each partial support phase. However, it is also conceivable to combine the two partial support phases within the full revolution of the output gear wheel 8 into a partial support phase group. A single compensation can now take place in the manner described above for the partial support phase group as a whole.

Reference sign

2

screw device

4

Housing

6

flat bottom gear

8th

output gear

10

angle head

12

screw tool

14

1. idler wheel

16

2. idler wheel

18

1. Jockey wheel

20

2. Support wheel

22

Start button

24

control unit

26

drive motor

28

torque sensor

30

compensation unit

32

geared offset

34

screwing device identification means

36

data interface

38

data interface

40

angle determining means

42

system boundary

44

cut

46

mechanical interface

48

direction of tightening

50

screw partner

52

display case

54

display case

56

display case

58

interface

60

sinusoidal wave

62

recess

64

data path

Claims (15)

1. A screwing device

   for applying and/or transmitting a torque to a screw partner and for interacting with a drive torque generating means, the screwing device comprising geared offset head means (6) having an output which can be connected to the screw partner in a detachable manner and a drive to which a drive torque can be manually or mechanically applied,

   an output gearwheel (8) which can be driven by the geared offset head means (6),

   a mechanical interface (46) for selective direct or indirect connection to the drive torque generating means for introducing the torque, characterized in that the screwing device furthermore comprises a compensation unit (30) configured to store and process compensation data comprising a torque curve specific to the output gearwheel and/or an efficiency curve specific to the output gearwheel for offsetting said data against a value of an actual output torque in order to generate a value of a compensated output torque, and

   a data interface (36) configured to transmit compensation data to a drive torque generating means.
2. The screwing device according to claim 1, comprising at least one torque detection means for detecting the value of the actual output torque.
3. A drive torque generating means

   for generating a torque and for interacting with a screwing device, the drive torque generating means comprising a drive motor (26),

   a mechanical interface (46) configured for selective direct or indirect connection to the screwing device (2) for introducing the torque,

   a torque detection means for detecting a value of the actual output torque, characterized in that the drive torque generating means furthermore comprises

   a compensation unit (30) configured to store and process compensation data comprising a torque curve specific to the output gearwheel and/or an efficiency curve specific to the output gearwheel for offsetting said data against the value of an actual output torque in order to generate a value of a compensated output torque, the drive torque generating means having a data interface (38) configured to transmit compensation data.
4. The screwing device according to claim 1 or 2 or the drive torque generating means according to claim 3, comprising a screwing device identification means.
5. The screwing device according to claim 1 or 2 or the drive torque generating means according to claim 3, comprising an angle determination means (40) for determining a position angle of the output gearwheel (8).
6. A screwing system at least comprising

   a screwing device (2) comprising

   geared offset head means (6) having an output which can be connected to the screw partner in a detachable manner and a drive to which a drive torque can be manually or mechanically applied,

   an output gearwheel (8) which can be driven by the geared offset head means (6),

   a mechanical interface (46)

   for selective direct or indirect connection to the torque generating means for introducing the torque,

   and a drive torque generating means

   connected to the geared offset head means (6) on the side of the drive and comprising

   a drive motor (26),

   a mechanical interface (46) configured for selective direct or indirect connection to the screwing device (2) for introducing the torque,

   a torque detection means for detecting a value of the actual output torque,

   characterized in that the screwing system furthermore comprises a compensation unit (30) configured to store and process compensation data comprising a torque curve specific to the output gearwheel and/or an efficiency curve specific to the output gearwheel for offsetting said data against the value of the actual output torque in order to generate a value of a compensated output torque.
7. The screwing system according to claim 6, comprising at least one data interface (36, 38) configured to transmit compensation data.
8. The screwing system according to claim 6 or 7, comprising an angle determination means (40) for determining a position angle of the output gearwheel (8).
9. A method for controlling a drive motor of a screwing system according to claim 6, the method comprising at least the following steps:

   - storing a torque curve specific to the output gearwheel and/or an efficiency curve specific to an output gearwheel in a compensation unit (30),

   - detecting a value of the actual output torque outputted by the drive motor (26) by means of a torque detection means,

   - offsetting the value of the actual output torque against at least one compensation file in order to generate a value of a compensated output torque, and

   - outputting the value of the compensated output torque to a control unit (24) of the drive motor by the compensation unit (30).
10. The method according to claim 9, wherein the offsetting comprises a comparison and/or a subtraction and/or an addition of a compensation file and the value of the actual output torque, preferably exclusively for at least one partial support phase, and/or wherein the offsetting comprises a smoothing of the value of the actual output torque, preferably exclusively for at least one partial support phase.
11. The method according to claim 9 or 10, further comprising the following steps:

    - determining the position angle of the output gearwheel (8) by means of an angle determination means (40), and

    - using the position angle in order to generate the value of the compensated output torque by the compensation unit (30).
12. The method according to any one of claims 9 to 11, further comprising the following steps:

    - defining a switch-off torque value, the drive motor (26) being switched off when the value of the compensated output torque of the drive motor (26) reaches the defined switch-off torque value, and

    - defining a target speed at which the drive motor (26) rotates, the target speed being dynamically adjustable in such a manner that it is as high as possible until the switch-off torque value is reached.
13. The method according to any one of claims 9 to 12, further comprising the following step:

    - operating the screwing system in speed control.
14. The method according to any one of claims 9 to 13, further comprising the following steps:

    - combining several partial support phases within a full rotation of the output gearwheel (8) in a partial support phase group, and

    - offsetting the value of the actual output torque against at least one compensation file in order to generate a value of a compensated output torque at least for the partial support phase group.
15. A use of a screwing system according to claim 6 for performing the method according to claim 9.

Images