Method for the documented tightening or tightening up of a screw connection

Abstract

In a method for the documented tightening or tightening up of a heavily loaded screw connection of a threaded bolt and a nut screwed on the threaded bolt by using an axially operating tensioning device and a process control unit provided with a documentation module, the screw connection is identified by scanning an identification provided on the screw connection and data determined by scanning the identification is stored in the documentation module. The screw connection is lengthened by the tensioning device by axially pulling on a threaded end of the threaded bolt and a tightening force (F.sub.A) and/or a tightening pressure (P.sub.A) exerted by axially pulling on the threaded end is stored in the documentation module. After lengthening, the nut is turned by using a hand torque wrench and an actually exerted hand torque applied for turning the nut is stored in the documentation module.

Claims

1. A method for the documented tightening or tightening up of a heavily loaded screw connection, comprised of a threaded bolt and a nut screwed on the threaded bolt, by using an axially operating, hydraulically driven tensioning device comprising a pump configured to adjust a hydraulic pressure of the hydraulically driven tensioning device, and a process control unit provided with a documentation module, the method comprising: identifying the screw connection by scanning with a sensor an identification provided on the screw connection and storing data, determined by scanning with the sensor the identification, in the documentation module; axially pulling on a threaded end of the threaded bolt projecting past the nut by applying hydraulically an axial tightening force (F.sub.A) with the hydraulically driven tensioning device to lengthen the threaded bolt and storing the axial tightening force (F.sub.A) and/or a tightening pressure (P.sub.A), applied by the hydraulically driven tensioning device to generate the axial tightening force (F.sub.A), in the documentation module; tightening the nut on the threaded bolt by using a hand torque wrench not until the threaded bolt has been lengthened by the step of axially pulling and storing an actually exerted hand torque applied for tightening the nut in the documentation module; and controlling the process control unit and the sensor with a common application program.

2. The method according to claim 1, further comprising, after identifying the screw connection, proposing to a user via the process control unit a stored tightening force (F.sub.s) and/or a stored tightening pressure (P.sub.s), stored in a database, before tightening of the screw connection is started by the user.

3. The method according to claim 1, further comprising, after identifying the screw connection, the process control unit automatically selecting a stored tightening force (F.sub.s) and/or a stored tightening pressure (P.sub.s), stored in the database, and further comprising automatically moving a pump to a pressure corresponding to the stored tightening force (F.sub.s) and/or the stored tightening pressure (P.sub.s) automatically selected by the process control unit.

4. The method according to claim 1, further comprising, after identifying the screw connection, the process control unit automatically selecting a stored tightening force (F.sub.s) and/or a stored tightening pressure (P.sub.s), stored in the database, and automatically starting tightening of the screw connection by using the stored tightening force (F.sub.s) and/or the stored tightening pressure automatically selected by the process control unit.

5. The method according to claim 1, further comprising using a tensioning device, wherein the tensioning device comprises a cylinder housing; an exchangeable bush mounted in the cylinder housing and provided at an end facing the threaded bolt with an internal thread, wherein the internal thread is configured to be screwed onto the threaded bolt; at least one piston axially movable in the cylinder housing and configured to be charged with a hydraulic pressure; wherein the exchangeable bush is centrally guided through the at least one piston, and wherein the exchangeable bush is configured to be axially entrained by the at least one piston.

6. The method according to claim 1, wherein the sensor is a constituent part of the tensioning device; of the hand torque wrench; or of a separate apparatus.

7. The method according to claim 1, wherein the sensor is a constituent part of a computer unit comprising the process control unit, wherein the sensor is a camera.

8. The method according to claim 7, wherein the computer unit is a mobile computer; a tablet computer; or a smartphone.

9. The method according to claim 1, further comprising connecting the sensor for signal processing to the process control unit.

10. The method according to claim 1, wherein the hand torque wrench and/or the tensioning device is provided with a transmitting and receiving unit connected for signal processing to the process control unit and providing a data exchange with the process control unit.

11. The method according to claim 1, wherein a signal connection between the hand torque wrench or the tensioning device and the process control unit is wireless.

12. The method according to claim 1, wherein a signal connection between the hand torque wrench or the tensioning device and the process control unit is provided by a wired link.

13. The method according to claim 1, wherein turning the nut is done by a gearing arranged on the tensioning device and provided with a rotary angle sensor, further comprising storing a rotary angle detected during turning by the rotary angle sensor in the documentation module.

14. The method according to claim 13, further comprising connecting the rotary angle sensor for signal processing to the process control unit.

15. The method according to claim 1, wherein the documentation module comprises a memory and/or a database.

16. The method according to claim 1, further comprising displaying an optical signal to the user as soon as the tightening and turning process is concluded.

17. The method according to claim 1, wherein the axially operating tensioning device is hydraulically driven.

18. The method according to claim 1, wherein the identification is a barcode identification configured to be scanned by a barcode scanner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the method according to the invention are apparent from the following description of an exemplary embodiment illustrated in the figures.

(2) FIG. 1 shows a threaded bolt with nut clamping two machine parts.

(3) FIG. 2 shows in a perspective view a hydraulically operating threaded bolt tensioning device, set in alignment with the threaded bolt and supported on the upper machine part. Also shown is a hand torque wrench for screwing an exchangeable bush onto the threaded bolt.

(4) FIG. 3 shows the same threaded bolt tensioning device as in FIG. 2 during the tensioning process.

(5) FIG. 4 shows the same threaded bolt tensioning device as in FIG. 2 and FIG. 3, when tightening up the nut with the hand torque wrench.

DESCRIPTION OF PREFERRED EMBODIMENTS

(6) The method according to the invention for the documented axial tightening or tightening up of a heavily loaded screw connection 1 is shown in FIGS. 1 to 4.

(7) As shown in FIG. 1, such screw connections 1 are comprised of a long threaded bolt 2 and a nut 3 screwed thereon. The screw connection 1 here tensions two machine parts 5, 6 to one another. Apart from the threaded bolt 2 and the nut 3 further elements can also be a component part of the screw connection 1, by way of example a further nut on the side remote from the nut 3 of the further machine part 6 which is to be tensioned. Washers are also often component parts of such screw connections 1. An identification 7 has to be arranged on the screw connection 1, thus on the threaded bolt 2 or the nut 3, for the method according to the invention. This is shown in FIG. 1 by way of example using a barcode 7 arranged on the end side 8 of the threaded bolt 2 or threaded bolt end. The identification 7 can however also be arranged at other places on the threaded bolt and/or nut.

(8) The barcode 7 is first scanned with a suitable sensor. The sensor or scanner can be arranged by way of example on a hand torque wrench 10 (FIG. 2) which as described below is used in any case within the scope of the method according to the invention. The sensor or scanner can also be part of a mobile computer unit, e.g. a tablet computer, a smartphone or a mobile computer unit. The sensor can be by way of example a camera. A separate scan module, which is used solely for scanning the identification 7, can also be used within the scope of the method according to the invention. The barcode can then be detected with the sensor and the screw connection 1 can be identified before the actual tightening or tightening up.

(9) An arrangement of the sensor or scanner in or on the tensioning device 11 itself can also be provided. The tensioning device 11 is then set on the bolt 2 which is to be tensioned and the barcode scanned immediately before tensioning.

(10) The information obtained by scanning is the basis for identifying the screw connection 1, e.g. the exact type of screw connection. The screw connection 1 is then in the next step lengthened by a solely axial pull on the threaded end 15 of the threaded bolt 2.

(11) For this extension process the operator or user can be offered processing parameters for tightening or turning by means of a process control unit for the relevant identified type of screw connection 1, by way of example by retrieving data pages with corresponding values stored in a database. The user can then confirm or decline the use of the parameters proposed to him. The method according to the invention can also be carried out without a parameter proposal of this kind.

(12) An automated method with automatic pressure adjustment of the pump of the hydraulic supply, and subsequent automatic start of the tightening process is possible.

(13) The heavily loaded screw connection 1 illustrated in FIG. 1 is tightened or tightened up by a purely axially operating hydraulically operated tensioning device 11. The tensioning device 11 and the procedure of tightening and tightening up are shown in FIGS. 2 to 4. The screw connection 1 is longitudinally extended by axially pulling on the threaded end of the threaded bolt 2 protruding over the nut. The tightening force F.sub.A thereby expended and/or the tightening pressure P.sub.A exerted by means of the hydraulics is automatically stored in the documentation module, namely independently of whether it is a tightening force set by the user from his experience, or a tightening force F.sub.s proposed by the system and derived from the values in a database and/or a stored tightening pressure P.sub.s.

(14) Whilst with the tensioning device 11 a predetermined pretensioning force F.sub.VM is exerted for a certain time on the threaded bolt 2 in the longitudinal direction of the bolt, the nut 3 of the screw connection 1 which is screwed onto the threaded bolt 2 can be tightened or retightened. This happens by means of a hand torque wrench 10. The hand torque M.sub.H actually exerted until released is likewise stored in the documentation module.

(15) The tensioning device 11 illustrated in perspective views in FIGS. 2 to 4 will be described in further detail below with reference to the method according to the invention. It should be noted that the tensioning device 11 is shown in the figures partially open in sectional view.

(16) An exchangeable bush 12 arranged centrally in the tensioning device 11 is provided at its lower end with an internal thread 13. The exchangeable bush 12 is screwed with this internal thread 13 onto the threaded end section 15 of the threaded bolt 2, which protrudes beyond the nut 3, prior to starting the tensioning process. This screwing takes place preferably with a hand torque wrench 10. For the actual tensioning process the exchangeable bush 12 screwed onto the threaded bolt 2 is set hydraulically under axial tension whereby the threaded bolt 2 is extended in the longitudinal direction by the length ΔL. The force F.sub.VM now acts on the threaded bolt 2.

(17) As result of the temporary lengthening of the bolt 2 the underneath side of the nut 3 becomes free so that the nut 3 can be turned first with little torsional resistance and then with increasing torsional resistance and can be tightened up in this way. A turning device 17 arranged around the nut is helpful here. This can be a constituent part of the tensioning device 11. The hand torque wrench 10 is set on the turning device 17.

(18) The hydraulic tensioning mechanism is enclosed by a pressure-resistant cylinder housing 18. The rigid projection of the cylinder housing 18 downwards forms a support tube 19 surrounding the nut 3. The support tube 19 can be integral with the cylinder housing 18 or alternatively a separate part from the cylinder housing 18 but can be placed thereon. The support tube 19 is open at its lower side and is supported on a fixed base, e.g. a machine part 5, which during the tensioning process serves as the abutment. With the method described here the abutment is that machine part 5 on which the nut 3 is supported with its underneath side.

(19) A gearing 17 operating through an opening in the support tube 19 can be provided to turn the nut 3. This gearing forms the turning device 17.

(20) The torque required for turning is applied by moving the hand torque wrench 10 set on the gearing 17 to and fro until the set torque is reached and the torque wrench 10 is released. The nut 3 can naturally only be turned whilst the tensioning device 11 is still working.

(21) A hydraulic connection 20 is located at the side on the cylinder housing 18 via which the hydraulic operating chamber 21 of the tensioning device 11 is connected valve-controlled to an external hydraulic supply. The external hydraulic supply together with the pump can be arranged for example on a trolley. In the hydraulic cylinder there is a piston 25 mounted movable in the longitudinal direction, sealed from the inside wall of the cylinder. The piston 25 is raised by feeding hydraulic pressure into the hydraulic operating chamber 21 of the cylinder. This can take place by way of example against the force of a strong spring which biases the piston 25 from above and which serves as a piston resetting spring and biases the piston 25 directly with a force which aims at keeping the piston 25 in its basic position in which the hydraulic working chamber 21 has its minimum level. This is not shown in the drawings and is optionally part of the tensioning device 10.

(22) The piston 25 encloses the exchangeable bush 12 in a ring. It is provided on its inner edge with a peripheral step 27 which facing away from the base forms an entrainment surface on which the exchangeable bush 12 is supported by a radially widened section 28 attached thereto. The exchangeable bush 12 is in this way axially entrained by the piston 25.

(23) The exchangeable bush 12 is provided on its bolt-side end with the internal thread 13 for screwing onto the threaded bolt 2. At its upper end the exchangeable bush 12 is provided with a socket 30 on which an angled corner of the hand torque wrench 10 can be set in order to turn the exchangeable bush 12 relative to the cylinder housing 18, and thus screw the exchangeable bush 12 onto the threaded bolt 2.

(24) The piston 25 rises under the hydraulic pressure in the working chamber 21 whereby it axially entrains the exchangeable bush 12 supported on the entrainment surface 27. This leads to the extension of the threaded bolt 2 and the formation of a gap ΔL between the underneath side of the nut 3 and the upper machine element 5. The hydraulic pressure can be set inside the apparatus as a result of scanning and thus identifying the type of screw connection 1 and the force values thus provided, or however after calculation by the operator.

(25) Extending the threaded bolt can be detected through suitable sensors, processed and where applicable likewise stored as a process value. The nut 3 is then turned with extended threaded bolt with the hand torque wrench 10 until reaching the torque release value M, for which the turning device 17 serves.

(26) Turning the nut 3 is carried out by means of the gearing 17 arranged on the tensioning device 11. At least one of the turning gearing elements of the gear is provided with a rotary angle sensor. This detects a rotary angle which is covered during the turning.

(27) The detected rotary angle can be the rotary angle of the nut 3 itself, or another characteristic rotary angle which one of the elements of the gearing carries out. The angle value thus detected is likewise stored for which the rotary angle sensor is connected by signal processing to the process control unit so that the detected rotary angle value is available in the process control unit for processing and evaluation.

(28) With this evaluation a statement on the remaining extension and with this the lengthening of the threaded bolt 2 is made from the rotary angle value covered in conjunction with the known thread pitch of the threaded bolt 2 and the nut 3. This extension value is documented in the documentation module.

(29) When the predetermined rotary angle, corresponding to the lengthening of the threaded bolt 2, has been covered and the nut 3 is then turned with the predetermined torque up to the stop, then it is ensured that the threaded bolt 2 has been tightened with the corresponding force.

(30) The tightening moment M actually acting on the nut 3 and applied by the hand torque wrench 10 is detected by a suitable sensor, e.g. through a torque sensor. This value is also transferred to the process control unit and stored in the documentation module.

(31) The transfer of the data and measured values detected during turning of the nut 3 can take place for example via a transmitting and receiving unit arranged on the hand torque wrench 10 or by a transmitting and receiving unit arranged on the turning device 17. These are then in signal connection with the process control unit. The torque M.sub.H actually applied is stored in the documentation module together with the axial tightening force F.sub.A or the hydraulic tightening pressure P.sub.A applied.

(32) Any number of different process variables can be stored and/or processed in the documentation module with a correspondingly large memory. By way of example the parameters can be stored in data tables or parameter files, e.g. in table format. These data can then be exported or printed as required, e.g. for proof of evidence.

(33) The specification incorporates by reference the entire disclosure of German priority document 10 2017 119 676.5 having a filing date of 28 Aug. 2017.

(34) While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

LIST OF REFERENCE NUMERALS

(35) 1 Screw connection

(36) 2 Threaded bolt

(37) 3 Nut

(38) 5 Machine part

(39) 6 Machine part

(40) 7 Identification, barcode

(41) 8 End side

(42) 10 Hand torque wrench

(43) 11 Tensioning device

(44) 12 Exchangeable bush

(45) 13 Internal thread

(46) 15 Threaded end section

(47) 17 Turning device, gearing

(48) 18 Cylinder housing

(49) 19 Support tube

(50) 20 Hydraulic connection

(51) 21 Operating chamber

(52) 25 Piston

(53) 27 Step

(54) 28 Radially widened section

(55) 30 Socket

(56) M Hand torque

(57) ΔL Length, gap

(58) P Pressure

(59) F.sub.VM Force