SCREWING DEVICE, DRIVING TORQUE GENERATING MEANS, SCREWING SYSTEM AND TORQUE CONTROL METHOD

Abstract

A screwing device for applying and/or transmitting a torque to a screw partner and for interacting with a drive torque generating means, including flat output means (6) which have an output that, can be detachably connected to the screw partner and a drive, to which a drive torque can be manually or mechanically applied, an output gearwheel (8) that can be driven by the fiat output means (6), a mechanical interface (46) for selective direct or indirect connection to the drive torque generating means for initiating the torque, a compensation unit (30) which is designed to store and process compensation data and which comprises an output gearwheel-specific torque curve and/or an output gearwheel-specific efficiency curve for calculating it with a value of an actual output torque in order to generate a value of a compensated output torque, and a data interface (36) which is designed to transmit compensation data to a drive torque generating means.

Claims

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, 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 indirection connection to the screwing device (2) for introducing the torque, a torque detection means for detecting a value of the actual output torque, and 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.

4. The drive torque generating means according to claim 3, comprising a data interface (38) configured to transmit compensation data.

5. The screwing device according to claim 1, comprising a screwing device identification means.

6. The screwing device according to claim 1, comprising an angle determination means (40) for determining a position angle of the output gearwheel (8).

7. 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 drive 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, and 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.

8. The screwing system according to claim 7, comprising at least one data interface (36, 38) configured to transmit compensation data.

9. The screwing system according to claim 7, comprising an angle determination means (40) for determining a position angle of the output gearwheel (8).

10. A method for controlling a drive motor of a screwing system according to claim 7, 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).

11. The method according to claim 10, 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, and/or wherein the offsetting comprises a smoothing of the value of the actual output torque.

12. The method according to claim 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).

13. The method according to claim 10 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.

14. The method according to claim 10 further comprising the following step: operating the screwing system in speed control.

15. The method according to claim 10 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.

16. The method according to claim 10, wherein the screwing system comprises the screwing system according to claim 7.

17. The method according to claim 11, wherein the comparison and/or the subtraction and/or the addition and/or the smoothing are exclusively for at least one partial support phase.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Further advantages, features and details of the invention are apparent from the following description of a preferred exemplary embodiment and from the drawings.

[0062] In the drawings,

[0063] FIG. 1 shows a perspective view of the handheld screwing system according to the invention;

[0064] FIG. 2 shows a schematic top view of the geared offset head means according to the invention (with the housing removed);

[0065] FIG. 3 shows a block diagram of components of the screwing system according to the invention;

[0066] FIG. 4 shows a protocol of a torque curve of an open geared offset head;

[0067] FIG. 5 shows a protocol of an efficiency curve of the open geared offset head according to FIG. 4;

[0068] FIG. 6 shows a protocol of a torque curve of a closed geared offset head;

[0069] FIG. 7 shows a protocol of an efficiency curve of the closed geared offset head according to FIG. 6;

[0070] FIG. 8 shows a diagram of a compensation in a partial support phase of an open geared offset head; and

[0071] FIG. 9 shows a diagram of the compensation of a partial support phase of an open geared offset head.

DETAILED DESCRIPTION

[0072] FIG. 1, the system view and, at the same time, context view for the present invention, shows a perspective view of a handheld screwing system having a screwing device 2 for applying a torque to a screw partner (not shown), screwing device 2 comprising geared offset head means 6 accommodated in a housing 4 of an open geared offset head 32. At one end (on the side of the output), geared offset head means 6 are configured to interact with and to drive a fitting screwing tool realized as a slotted output gearwheel 8. On the side of the drive, i.e., at the end of geared offset head means 6 opposite to the output, geared offset head means 6 are connected to a manually actuatable drive torque generating means via an angle head 10 having a pair of gearwheels or cone gearwheels, if applicable, via a mechanical interface 46, the drive torque generating means being realized as a screwing tool 12.

[0073] Screwing tool 12 has a drive motor 26 (e.g. electric or pneumatic) and applies its generated output torque to screwing device 2. Both screwing device 2 and screwing tool 12 each have a mechanical interface for selective direct or indirect connection to the other of the two partners of the screwing system.

[0074] In a typical realization for the manual screwing actuation, such screwing devices 2 or geared offset head means 6 are provided and suitable for the transmission of a maximum torque of approx. 250 Nm.

[0075] Screwing device 2 is designed as an open geared offset head and is characterized in that output gearwheel 8 has a recess 62 realized as a slot for the radial reception of a screw partner in a hexagon socket. Alternatively, the screwing device shown in the figures can be designed as a closed geared offset head. Both designs have identical influences indicated above which deteriorate the efficiency and whose effects are excluded for both designs by means of the invention. Additionally, the open design has the impact on the efficiency during the partial support phase, the effects of which can also be excluded according to the invention.

[0076] FIG. 2 shows several geared offset head means 6 or gearwheels of screwing device 2 in a top view with housing 4 being removed and an output gearwheel 8 on the side of the output. The output torque outputted by drive motor 26 is applied to a first idler gearwheel 14, a second idler gearwheel 16 and a first support gearwheel 18 and a second support gearwheel 20. The two support gearwheels 18 and 20 transmit the torque to output gearwheel 8 by meshing accordingly.

[0077] Gearwheels 8, 14, 16, 18 and 20 are mounted axially parallel to one another and are disposed in a linear manner along a length of housing 4 so as to be rotatable in housing 4. An arrow indicates a tightening rotation direction 48 of output gearwheel 8.

[0078] During a full rotation of 360°, output gearwheel 8 passes through two full support phases and two partial support phases. In the full support phases, output gearwheel 8 engages with the two support gearwheels 18 and 20. In the partial support phases, output gearwheel 8 engages with only one of the two support gearwheels 18, 20. In terms of angle positions—0° pointing to an attachment position in the longitudinal direction of housing 4 and being referred to as zero position in which output gearwheel 8 can be attached to a screw partner—this means that a first full support phase starts at an angle position of 230°, passes an angle position of 0° and extends up to an angle position of 130°. The first partial support phase starts at an angle position of 130° and extends up to an angle position of 170°. Said first partial support phase is followed by a narrow second full support phase between an angle position of 170° and 190°. Finally, output gearwheel 8 passes through a second partial support phase between an angle position of 190° and 230°. The full support phases and the partial support phases thus alternate.

[0079] During each of the two partial support phases, sluggishness occurs and leads to deteriorated efficiency, as shown in FIG. 5. Sluggishness can also occur in the narrow full support phase.

[0080] FIG. 3 provides an overview of various means and elements of the screwing system according to the invention and adjacent systems.

[0081] Screwing tool 12 comprises a start button 22 for the operation of screwing tool 12 by an operator. An energy supply and a control unit 24 are activated by means of start button 22. When the screwing system is operated in speed control, a speed is defined and control unit 24 readjusts, inter alia, a torque outputted by a drive motor 26 by means of signals outputted to drive motor 26. To this end, drive motor 26 can comprise a planetary gear (not shown), for example. Drive motor 26 can transmit its position and/or its rotation angle to control unit 24 by means of signals. Drive motor 26 outputs an actual output torque which is detected as a value by a torque sensor 28 which is used as a torque detection means.

[0082] A control loop for controlling the drive motor of the screwing system starts at this point. In fact, torque sensor 28 transmits the detected actual output torque or its value outputted by drive motor 26 to a compensation unit 30. A torque curve specific to the output gearwheel or an efficiency curve specific to the output gearwheel is stored in compensation unit 30. Among other things, compensation unit 30 is configured to offset the value of the actual output torque against the torque curve specific to the output gearwheel in order to generate a value of a compensated output torque. In other words, the sluggishness which is caused by the output gearwheel and which is reflected as a peak in the value of the actually outputted output torque is removed or compensated. Compensation unit 30 then transmits the value of the compensated output torque to control unit 24. Control unit 24 is configured to compare the value of the compensated output torque with a switch-off torque, drive motor 26 being switched off when the value of the compensated output torque reaches the switch-off torque.

[0083] By switching off drive motor 26 when the switch-off torque is reached, the invention shows and ensures that a screwing process has been executed to a successful end, i.e., until a fixed or defined screw connection has been established. An early switching off caused by the sluggishness of screwing device 2 and the increase of the torque caused thereby to above the switch-off torque, as the case may be, is now excluded.

[0084] In addition, control unit 24 processes the value of the compensated output torque in the same known way as a value of an actual output torque in a known control loop of a motor control.

[0085] The torque outputted by drive motor 26 is outputted to screwing device 2 via the mechanical interface. In the embodiment shown in FIG. 3, screwing device 2 comprises angle head 10 and a geared offset head 32 which comprises geared offset head means 6 and output gearwheel 8. The torque is ultimately transmitted from output gearwheel 8 to screw partner 50 in order to establish a fixed screw connection.

[0086] The drive torque generating means or screwing device 2 can comprise a screwing device identification means 34 which can transmit an identification of, for example, the design, geared offset head means 6, geared offset head 32 and/or the transmission ratio to screwing tool 12 in a wired or wireless manner. To this end, a data interface 36 can be used to transmit compensation data, for example. Screwing device 2 can also comprise a data interface 36 in order to receive compensation data, for example, from screwing device 2 and/or to receive data from an external data source or to send said data to the external data source. For example, screwing device 2 can comprise an angle determination means 40 for determining a position angle of output gearwheel 8. Said measured value of the angle position can be transmitted by means of one or both data interfaces 36 and 38, for example. The transmission is indicated by means of an idealized data path 64 which transmits the measured value of the angle position from angle head 10 and/or angle determination means 40 to control unit 24 for further processing.

[0087] An example of a measurement is shown within a system limit 42. To this end, a screwing device 2 is connected in combination with a screwing tool 12 or a drive torque generating means and at least one full rotation of output gearwheel 8 is detected, as shown in block 52. In this regard, the focus is on the transmitted torque and the efficiency. For example, more than 50 full rotations or screwing cycles can preferably be recorded, as shown in block 54. FIG. 6 shows the resulting measurement signal of the torque. Said measurement signal is further processed in block 56 in a manner not described in further detail and is digitalized, if required. The measurement signal is then transmitted to compensation unit 30, for example, by means of an interface 58 for data transmission and is stored there. However, the measurement signal can also be stored in a suitable memory of screwing device 2.

[0088] FIG. 4 shows the measurement curve of an open geared offset head which has an output gearwheel 8 meshing with two support gearwheels 18 and 20 as detected within system limit 42. A combined view of FIGS. 4 and 5 shows the realization on which the invention is based. It was noted that the sluggishness of screwing device 2 occurs in a cyclic manner. Drive motor 26 tries to compensate for said sluggishness in speed control, for example, by increasing the outputted output torque, as shown by the peaks in FIG. 4. The result is the efficiency curve which is shown in FIG. 5 and which drops significantly every 360°. The efficiency drop coincides with the sluggishness and it can therefore be concluded that a change of the value should have the effect that a drive motor 26 does not have to react to sluggishness by increasing the outputted output torque, which ultimately leads to improved efficiency.

[0089] FIG. 6 shows the measurement curve of a closed geared offset head which has an output gearwheel meshing with only one support gearwheel as detected within system limit 42. FIG. 7 shows the efficiency curve resulting directly therefrom. Compared to the measurement curves of the open geared offset head shown in FIG. 5, this measurement curve shows a steadier course. An averaging of the efficiency course shows a sinusoidal wave 60 which has a cyclic behavior. In this case, the wave repeats with each rotation of the output gearwheel every 360°.

[0090] FIGS. 8 and 9 show compensation examples or two options of drive motor controls. Although the following description refers solely to the geared offset head, the mentioned principles can also be used in a closed geared offset head.

[0091] In FIG. 8, a torque specified in newton meters is plotted in relation to a rotation angle specified in degrees in a schematically simplified manner. The value of a switch-off torque is shown by means of a coarse dashed line. The value of the actually outputted output torque is shown by means of a medium-fine dashed line. The value of the torque curve specific to the output gearwheel as a compensation file is shown by means of a finely dashed line. The value of the compensated output torque is shown by means of a solid line.

[0092] It can be seen that drive motor 26 tries to compensate sluggishness between an angle position of 130° and 170° of output gearwheel 8 by outputting an increased output torque−the torque peak shown in FIG. 6. Compensation unit 30 offsets the value of the actually outputted output torque against the value of the torque specific to the output gearwheel at least for this partial support phase between 130° and 170°. By comparison with the value of the torque specific to the output gearwheel, compensation unit 30 detects that a cyclic torque peak occurs in said angle range (130° to 170°)—a clear indication of a torque peak caused by the output gearwheel. The result of this offsetting is the schematically shown value of a compensated output torque. Said output torque increases regardless of the compensation according to the invention and reaches the switch-off torque at point 44. At point 44, control unit 24 causes a switching off of drive motor 26. At that time, a tight screw connection is assumed.

[0093] FIG. 9 is largely similar to FIG. 8, which is why the following description shall merely focus on the differences.

[0094] It can be seen that output gearwheel 8 has a first partial support phase between a rotation angle of 130° and 170° and a second partial support phase between a rotation angle of 190° and 230°. A full support phase in an angle range from 170° to 190° is located between the two partial support phases. The two partial support phases are flanked by another full support phase which ranges from a rotation angle of 230° through a zero position of 0° up to a rotation angle of 130°. A compensation of the two torque peaks in the partial support phases can take place separately for each partial support phase. However, it is also conceivable to combine the two partial support phases within the full rotation of output gearwheel 8 in a partial support phase group. This allows for the realization of a single compensation for the partial support phase group as a whole in the manner described above.

REFERENCE SIGNS

[0095] 2 screwing device

[0096] 4 housing

[0097] 6 geared offset head means

[0098] 8 output gearwheel

[0099] 10 angle head

[0100] 12 screwing tool

[0101] 14 first idler gearwheel

[0102] 16 second idler gearwheel

[0103] 18 first support wheel

[0104] 20 second support wheel

[0105] 22 start button

[0106] 24 control unit

[0107] 26 drive motor

[0108] 28 torque sensor

[0109] 30 compensation unit

[0110] 32 geared offset head

[0111] 34 screwing device identification means

[0112] 36 data interface

[0113] 38 data interface

[0114] 40 angle determination means

[0115] 42 system limit

[0116] 44 cut

[0117] 46 mechanical interface

[0118] 48 tightening rotation direction

[0119] 50 screw partner

[0120] 52 block

[0121] 54 block

[0122] 56 block

[0123] 58 interface

[0124] 60 sinusoidal wave

[0125] 62 recess

[0126] 64 data path