Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
  • B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
  • B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
  • B25B23/145—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for fluid operated wrenches or screwdrivers
  • B25B23/1456—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for fluid operated wrenches or screwdrivers having electrical components
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
  • B25B21/00—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose
  • B25B21/004—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose of the ratchet type
  • B25B21/005—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose of the ratchet type driven by a radially acting hydraulic or pneumatic piston
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
  • B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
  • B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
  • B25B23/145—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for fluid operated wrenches or screwdrivers

Definitions

• the present invention relates to a method for controlling a double-acting cylinder actuated by a pressurized fluid in an assembly, such as a hydraulic tightening key and its control, in which a reciprocating movement can be repeated.
• the object of the present invention is to avoid the use of such a sensor, or of any other device.
• auxiliary device of this kind which must be mounted in the tightening key, which must be supplied from outside for its operation and from which the end of travel signal must be taken out to bring it to a means of exploitation of the latter.
• the costs of installing such a sensor in the tightening key are considerable compared to those of the key itself and the incorporation of this sensor therein, often used under conditions of high stresses especially in the active travel direction, increases the risk of malfunction of the tightening key, for example by false information supplied by said sensor.
• the method of the present invention is developed to exploit to the maximum and in a safe manner, preferably automatically by means of programmable devices, the information provided by means of detection and measurement of the hydraulic pressure, and which is provided outside. of the hydraulic key itself.
• the method according to the invention comprises:
• the present invention also relates to a device for implementing the above method.
• the device includes:
• Figure 1 schematically shows the main elements of a tightening wrench that can be used in the process of one inven ⁇ tion.
• FIG. 2 schematically represents a set of hydraulic and electronic controls of the hydraulic cylinder of FIG. 1.
• FIG. 3 represents a functional diagram of the electronic part of the control assembly of FIG. 2.
• a double-acting cylinder 2 is actuated by pressurized oil via an input 3 for the active stroke in the direction of movement 4 of movement d 'a piston 5 and via an input 6 for the passive stroke in the direction 7 of the return of the piston 5 for a new active stroke.
• a rod 8 fixed to the piston 5 pushes by its free end 9, directly or indirectly, a tooth 10 of a ratchet wheel 11, on a circle of radius R, so that it rotates by a value corresponding to the length of the active stroke, for example in a direction of tightening of a nut (not shown) housed in a suitable recess 12 of the wheel ratchet 11.
• a non-return pawl 13 and its spring 14 are also shown in this diagram: they prevent the wheel 11 from accompanying the rod 8 in its return stroke in * the direction 7.
• the jack 2 is supplied with pressurized fluid through the inlet 3, in the direction 4 of the active stroke. It is detected during this stroke in direction 4 that the fluid pressure reaches the set pressure Pc.
• This detection can mean that either the piston 5 has come to a stop at the end of its active stroke or the nut offers a resistant torque Cr desired.
• the cylinder is supplied in the opposite direction via the input 6 for the passive return stroke in the direction 7. The moment when the piston 5 comes to a stop at the end of its stroke is detected by suitable means. passive back.
• the time Te elapsed between the start of the supply of fluid via the inlet 6 and the time of arrival of the piston 5 in abutment of said return stroke is measured for this return stroke.
• This elapsed time Te is compared to a determined time Td which corresponds to that of a complete return stroke under the same operating conditions of the jack 2 (by example for the same temperature and therefore viscosity of the oil used). If the time Te is substantially equal to the time Td, the piston 5 has made a complete return stroke and there is no certainty that the pressure Pc obtained at the end of the previous active stroke corresponds to a tightening torque desired Cr of the nut. In this case, the tightening sequence is repeated each time comprising a complete active stroke and a complete passive stroke and the detection, measurement and comparison operations, until the measured elapsed time Te is substantially less than the time Td .
• the pressure of the fluid at the inlet 6 reaches or exceeds a determined pressure greater than that which is necessary for the piston to carry out this return stroke with certainty and regularity.
• This determined pressure can preferably be equal to the aforementioned pressure Pc which then will not be exceeded.
• time Tec can be measured for example during one or two sequences of no-load operation of the hydraulic tightening key 1, carried out in order to put the key and its control just before its use in a known initial state.
• a typical installation for the implementation of the aforesaid method may comprise for example (FIG.
• a hydraulic control part 19 comprising an oil reservoir 20 in which is immersed a suction filter 21 connected to the inlet of a pump 22, the outlet of which discharges the oil in a pipe 23.
• a pressure li itor 15 for example set to 700 bars
• a solenoid valve 24 to supply the inlet 3 of the jack 2
• a solenoid valve 25 for supplying the input 6 of the same jack 2.
• a transducer 26, known per se can be connected to the line 23 and is then chosen to give a current signal I as a function of the pressure P that it detects in the pipe 23.
• control device 29 of the invention preferably electronic with microprocessor and one embodiment of which is shown in FIG. 3 by way of example.
• the control device 29 can comprise, in addition to a supply which is not shown, means in the form of an introduction keyboard for the selection 30 of a set pressure Pc for the fluid, as a function of the desired maximum force F during at least the active stroke in the direction 4 of the piston 5.
• the keyboard 30 is connected to comparison means 31 which can be constituted by an 8-bit microprocessor 31.
• a means 32 for input and adaptation of a signal corresponding to the pressure supplied to the actuator 2 during its active stroke along arrow 4 and preferably also during its passive stroke along arrow 7, this signal being supplied for example by the above-mentioned transducer 26.
• the microprocessor 31 can selectively control the actuator 2 by means of the solenoid valves 24 and 25 preci ⁇ ted, via a link interface 33. In the case of the example shown here the detection of the end of the return stroke according to arrow 7 is also carried out using the transducer 26.
• a clock 34 in real time is connected to the microprocessor 31 for measuring the time elapsed Te between the start of the passive return race and its completion.
• a RAM memory 35 connected to the microprocessor 31 is used to store inter alia the determined time Td as well as other parameters and data of the system. This RAM memory 35 is assisted by an accumulator 36 for saving the value of the time Td and of these parameters and data.
• An EPROM memory 37 contains an operating program for the control device 29, the progress of which is clocked by the clock 34.
• a control logic 38 connected, according to FIG. 3, to the various elements of the device 29 ensures the chronology data transfers between these elements.
• control screen 39 for checking the data entered, system parameters, etc.
• This remote control 40 can also include a display of for example the pressure reached at any time or the torque actually reached during tightening.
• the microprocessor 31 and the program are also arranged to compare the measured elapsed time Te and the determined time Td and to decide automatically to repeat clamping the following sequence as Te aforesaid process is substantially equal to Td and to stop any repetition when it is assured that Te is manifestly less than Td.
• the transducer 26 has been considered here as being external to the control device 29 as such, there may be cases where it is preferred that it be included therein.
• a typical operation of a clamp assembly provided with this device 29 takes place as follows.
• the set pressure Pc is introduced into the device 29 via the keyboard 30 and a tightening sequence is started via the remote control 40.
• the microprocessor 31 executes a program which makes it possible to set the piston 5 of the key 1 in motion while measuring by the transducer 26 the oil pressure P in the hydraulic circuit (line 23).
• the movement of the piston 5 is repeated back and forth according to the program of the EPROM memory 37, the direction of movement of the piston 5 being reversed with each increase in the oil pressure beyond the preset threshold Pc.
• the piston 5 When the piston 5 reaches the active end of stroke, it usually takes a time Tec for the return stroke greater than a time Te for a return stroke from any position it would have reached before the end of the active stroke during tightening to the desired torque Cr of a nut or a screw. The back-and-forth movement of the piston 5 is then stopped when it has been observed by the micropro ⁇ cessor 31 that the desired tightening torque has actually been reached. The tightening torque actually reached can be displayed on the remote control 40, which allows the user to monitor the tightening progress.
• the invention is in no way limited to the embodiments described and that many modifications can be made to these without departing from the scope of the present invention.
• the device 29 can be provided with a manual or automatic operating selection to allow the operator to decide whether or not himself either to stop the tightening sequences of an element or to repeat it multiple times. sequences, even after obtaining the desired tightening torque.
• Td time Td as a function of the temperature of the oil in service
• a memorization of Td values as a function of the measured temperature can be carried out and a selection of the appropriate Td value can be made by the microprocessor 31 responsible for example also for blocking the tightening assembly in case the temperature oil is not within chosen limits.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=3887513

Family Applications (1)

Country Status (6)

Families Citing this family (12)

Family Cites Families (8)

• 1993
  • 1993-10-29 BE BE9301196A patent/BE1007527A3/fr not_active IP Right Cessation
• 1994
  • 1994-10-28 WO PCT/BE1994/000079 patent/WO1995011777A1/fr active IP Right Grant
  • 1994-10-28 DE DE69405243T patent/DE69405243T2/de not_active Expired - Lifetime
  • 1994-10-28 US US08/635,896 patent/US5737992A/en not_active Expired - Lifetime
  • 1994-10-28 EP EP94930883A patent/EP0724504B1/de not_active Expired - Lifetime
  • 1994-10-28 AU AU79871/94A patent/AU7987194A/en not_active Abandoned

Non-Patent Citations (1)

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