FR2868723A1 - Mechanical dynamometric tool e.g. wrench, for applying torque, has processing unit which permits to perform calculations on digital data that is obtained by electronic processing of signal - Google Patents

Abstract

The tool has a mechanical balance break detection unit with a measurement unit (121) providing a signal corresponding to measurement of torque applied to a fixation unit. An amplifier (201), an analog/digital double conversion device (203) and a microcontroller (205) electronically process the signal. A processing unit (215) permits to perform calculations on digital data obtained by electronic processing of the signal. An independent claim is also included for a process of detecting a break of a mechanical balance.

Description

TOOL, IN PARTICULAR KEY, DYNAMOMETRIC AND METHOD OF

  BALANCE BREAKAGE DETECTION DURING TORQUE TIGHTENING.

  The present invention relates to a tool, in particular a mechanical torque wrench with manual application of the torque, comprising mechanical means able to provide a predetermined torque to a driving part intended to cooperate with a screwing member to drive a fastener element. said mechanical means being in equilibrium under the action of suitable biasing means, said mechanical means being releasable by breaking of equilibrium, and means for detecting the breakage of equilibrium.

  In known manner, clamping operations of fasteners in the industrial sector require more and more traceability, ie knowledge of all the information and measures to follow and quickly find the steps of the process.

  For the tightening operations, the dynamometer tool manufacturers propose mechanical tools, the principle of which is based on a strongly perceptible breaking of the equilibrium, making it possible to detect the breakage of equilibrium by a device comprising an electric circuit provided with a means switch whose state is changed by the break equilibrium, and a processing unit, adapted to exploit the information relating to the state of said switching means. The entire detection device is generally housed in a casing fixed externally to the body of the tool.

  Such a construction is not entirely satisfactory, because the housing defines a protuberance at the periphery of the body of the tool, potentially annoying for the introduction of the tool into a mechanical member on which the operator intervenes.

  In addition, such a construction uses a miniature switch whose life is relatively short, and which poses reliability problems when it is subjected to sudden actuations, which is generally the case for tools breaking balance. mechanical.

  A main purpose is to overcome these disadvantages, and provide a mechanical torque tool whose size does not increase and whose reliability is increased.

  For this purpose, in a mechanical dynamometric tool according to the invention, the mechanical equilibrium break detection means comprise measurement means which provide a signal corresponding to the measurement of the torque applied to the fastening element, electronic processing means of said signal and processing means by computing data from the electronic processing of said signal.

  According to other features of the invention: the calculation means detect the moment of the mechanical equilibrium break by calculating derivative of the measurement value of the torque with respect to time.

  the calculation means detect the moment of the mechanical equilibrium break by calculating the intersection of a first and a second curve, the first curve representing the measurement value of the torque with respect to time, the second curve being identical at the first with a positive shift in time; the electronic signal processing means and the calculation means are arranged inside the key; the key further comprises means for transmitting the measurement of the maximum tightening torque applied to the fastening element at a station external to the tool, and in that said station displays the value of maximum tightening torque applied to the fastening element; the key further comprises means for transmitting the measurement of the maximum tightening torque applied to the fastening element to receiving means integral with the tool, and in that the said means display the value of the tightening torque. maximum applied to the fastener; the measuring means comprise resistive sensitive elements; the measuring means comprise a plurality of strain gages, mounted in a bridge; the dynamometric tool is a trigger key; the dynamometric tool is a key to break; the dynamometric tool is a screwdriver; the information is transmitted by radio frequencies.

  The invention also relates to a mechanical balance failure detection method during a manual torque tightening of a fastener element when the applied torque reaches a predetermined target torque, the method comprising the following steps: the provision of information corresponding to the measurement of the torque applied to the fixing element, the electronic processing of said information, the processing by calculation of digital data resulting from the electronic processing of said information.

  A particular embodiment of the invention will now be described in more detail with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a torque wrench according to the invention; Figure 2 is an exploded perspective view of the key illustrated in Figure 1; Figure 3 is a longitudinal sectional view along the line III-III shown in Figure 1; Figure 4a is a graph of a measurement curve corresponding to the time-dependent tightening of the key illustrated in Figure 1; FIG. 4b is a graph of a calculation mode of the detection of the equilibrium break of the key illustrated in FIG. 1; Fig. 5 is an operation flow diagram of the key illustrated in Fig. 1; FIG. 6a is a flowchart according to a first method of detecting the break in equilibrium of the key illustrated in FIG. 7 is an electronic schematic diagram of the key of FIG. 1.

  In Figures 1 to 3, there is shown a torque wrench according to the invention, the key having a longitudinal axis X-X, oriented from back to front. The key 1 which has been shown essentially comprises a tubular assembly 3 of generally cylindrical shape, defining an external hollow body, a head or drive element 5 towards the front of the key, a handle assembly 7 for grasping the tool , located towards the back of the key.

  The tubular assembly 3 is formed of an outer sleeve 3a defined by a cylindrical sleeve, and of an inner tube 3b, the sleeve 3a being fit-fitted on the tube 3b and covering the tube 3b in the front part of this tube. latest.

  The sheath 3a, the tube 3b and the head 5 are preferably metal parts.

  The key shown is of the type of production trigger, ie the type used in the production workshop to tighten following a large number of identical elements of bolts, to the same predetermined torque. For this type of tool, it is not necessary to readjust the triggering torque frequently. It is understood that the invention applies as well to a so-called production key, particularly trigger as shown in the figures or breakage, an adjustable torque wrench. 4a

  FIG. 6b is a flowchart according to a second method of detecting the break in equilibrium of the key illustrated in FIG. 4b. On the key represented, the handle assembly 7 is fixedly mounted on the tube assembly 3, the end proximal to the handle assembly 7 comprising a plug 111 having a shutter 119 preserving a passage inwardly of the tubular assembly 3.

  Note that a flexible antenna 87, whose function will be described later, protrudes behind the plug 111.

  As will also be described later with reference to FIGS. 2 and 3, the setpoint torque adjusting members are accessible by means of a tool inside the tubular assemblies 3 and the handle 7, after the shutter 119 has been removed. cap 111.

  The key 1 represented in FIGS. 2 and 3 has a handle assembly 7 comprising a handle-holder 71 of generally cylindrical shape extending coaxially with the axis XX of the key in which a support module 41 is mounted and fixed, said support-handle 71 being fitted and fixed on the rear part of the tube 3b. The handle assembly 7 also comprises a sleeve 101 partially covering the support-handle 71, and on which it is fixed. The rear end of the sleeve 3a engages with play in the front end of the handle holder 71.

  The drive head 5 is a part which comprises a front block 21 projecting from the front of the tube assembly 3, an intermediate hinge zone 23, and a rear tail 25 fitted with play in the tube 3 and mounted with possibility of pivoting on the tube 3 around a ZZ axis represented by a pin 27. The drive head also comprises, located between the front block 21 and the hinge zone 23, an elastic bar 26 having in cross section a rectangular shape of constant dimensions along its entire length. The bar 26 has side faces 26a made in a plane parallel to the axis Z-Z, so that they undergo the deformations of the bar 26.

  The pin 27 traverses diametrically the hinge zone 23, the sleeve 3a and the tube 3b being integral with the latter two.

  The block 21 has, from its front end, an attachment 29, in which can be fitted and attach an actuator (not shown). The latter is typically a reversible reversible ratchet head, provided with a drive square on which fits a screw socket. i0

  Note that in Figure 3, the X-Z plane of section is assumed to be vertical and the X-X axis is assumed to be horizontal, for convenience of description. The orientation of the key shown in this figure corresponds to the actuation of a screw or a nut (not shown) whose axis is vertical.

  In the use configuration of the key as shown in FIG. 3, the following elements are arranged coaxially inside the tube 3b, from rear to front, to the rear end of the shank 25: a first externally threaded cylinder 91, provided on its rear end face 94 with a central bore 95 passing through from one side, and an external thread cooperates with an internal thread formed on at least one rear section of the tube 3b. The threaded cylinder 91 can thus be screwed and defines a rear axial stop; a second externally threaded cylinder 31, provided with a drive shape 33 to turn towards the rear end of the tube 3b, and an external thread of which cooperates with the internal thread formed on a rear section of the tube 3b. The threaded cylinder 31 can thus be screwed or unscrewed inside the tube 3b so as to be displaced axially, and, in the unscrewed position, comes into rear axial abutment on the threaded cylinder 91; a compression spring 61 (shown symbolically in FIGS. 2 and 3) having a high stiffness and whose rear end bears on the front end of the cylinder 31; a plate 63 ball 64, this plate being secured to the front end of the spring 61; a pusher 65 is of generally cylindrical shape having a rear face bearing on the ball 64. The pusher can slide axially while being guided in the tube 3b, under the effect of biasing the spring 61, transmitted by the plate 63 and the ball 64; - A cubic die 67 applies, at rest, on the bottoms of two recesses, one formed in the rear face of the tail 25 and the other in the front face of the pusher 65, these faces being vertical facing the one of the other.

  The assembly formed of the pusher 65 and die 67 defines an axial bearing means on the drive head 25.

  It is understood that the axial position of the threaded cylinder 31 determines the compression of the spring 61, and thus the axial bearing force of the pusher 65 on the tail 25, through the die 67. When the set torque determined by the compression of the spring 61 is reached, the die 67 tilts and backs the pusher. The tail 25, by pivoting around the pin 27, then comes into contact with the inner surface of the tube 3.

  Note that this relatively violent contact, due to a break in mechanical balance, causes a physical sensation to the operator and clearly indicates that the target torque has been reached.

  As shown in Figures 2 and 3, the handle assembly 7 comprises a support module 41 of electrical / electronic means and / or power supply. The support module 41 comprises a support comprising recesses and / or housing and end faces adapted respectively to receive power supply members 42, such as AAA type batteries and electric / electronic circuit boards.

  As shown in FIG. 2, the proximal end 74 of the handle holder 71 has a longitudinally extending tubular section of shape and size adapted to receive the module holder 41.

  An elongate lumen 75 is made axially and spaced from the proximal end face 74 over a half circumference of the outer wall of the handle-holder 71.

  When mounting the support module 41 in the handle holder 71, the recesses adapted to receive the power supply members 42 are positioned opposite the elongate light 75 of the handle-holder 71. This configuration allows quick access to the batteries. 42.

  After mounting the carrier module 41 in the handle holder 71, a fastener 86 holds the carrier module 41 in position in the handle holder 71.

  As shown in FIG. 2, measuring means 121 for the deformation of the elastic bar 26 of the driving head 5 consist of measuring element sensitive elements, such as bonded resistive extensometers (strain gages) on the faces 26a of the bar 26. Known measuring means of another type may be used within the scope of the present invention.

  A thin elongated insulating plate 121 carrying extensometers formed and wired directly onto it is fixed rigidly, and in a manner known per se, on a lateral face 26a of the bar 26.

  The extensometers are connected to a sheet of conductive wires 123.

  This web 123 travels through an inner conduit of the tail 25 of the drive head 5, just behind the hinge zone 23, through an inlet port 26b in communication with an outlet port 26c. The sheet 123 then passes through an oblong slot 3c located in the distal portion of the tube 3b to continue its path, inserted in a longitudinal groove 3d made on the outer surface of the tube 3b.

  The end of the ply 123 opposite the plate 121 carrying the extensometers is connected to a connector 124, itself connected to one of the electrical circuit plates of the support module 41 via a clearance 77 made on the handle holder 71 between the lumen 75 and the distal end 72 in the half circumference opposite that of the lumen 75.

  In addition, the handle holder 71 has, between the clearance 77 and the distal end 72, a groove 78 is adapted to receive a seal 80, such as an O-ring.

  The plug 111, shown in FIGS. 2 and 3, also comprises a passage 118 extending in the X-X axis of the key 61 and in the extension of a central duct 47 of the support module support 41.

  This arrangement allows an operator to introduce a screwdriver blade or a male key to access from the outside to the drive portion 33 of the second threaded cylinder 31 passing successively and from outside, the plug 111, the support module 41, the first threaded cylinder 91.

  The plug 111 also comprises a passage 120 capable of passing a flexible antenna 87 connected to one of the electrical / electronic circuit boards 30 of the support module 41.

  The method of detecting mechanical breakage during manual tightening to the torque of a fastener element when the applied torque reaches a predetermined target torque according to the invention is decomposable according to the following steps: -Io- the measurement of the deformation of the test bar 26 related to the use of resistive sensitive elements 121, corresponding to the measurement of the torque applied to the fixing element, the electronic processing of a signal resulting from said measurement, the processing by calculation of numerical data resulting from said electronic processing, computational processing capable of providing information relating to the detection of the mechanical equilibrium break. Resistive sensitive elements such as extensometers or strain gauges 121, are connected, of known manner, in a Wheatstone bridge circuit, translating the deformation of the test bar 26 in resistance difference. The batteries or accumulators 42 located on the support module 41 constitute the voltage source supplying the bridge circuit.

  The support module 41 comprises electronic means for processing the signal from the strain gages 121. The support module 41 also comprises electronic calculation means for detecting whether or not the mechanical equilibrium break occurred. The support module 41 also comprises electronic means for transmitting information corresponding to the detection of break of equilibrium and / or the measurement.

  As shown in FIG. 7, the electronic diagram comprises a bridge gage circuit 121 connected to one or more amplifier inputs 201. The output of the amplifier is connected to an analog / digital double conversion device 203 and a microcontroller 205. Electronic memory means 207 can store one or more information. Means 215 make it possible to perform calculations on digital data from the preceding electronic devices. The power supply of these elements is provided by the batteries 42. -1I-

  Information from the electronic equipment of the key described above can be remotely transmitted 217 to a control equipment 219 via a transmission module 209 and an antenna 87. In other variants, these The same information can be displayed via a display device such as a display 211 or a light emitting diode display 213. The operation of a clamping sequence will now be described.

  FIG. 4a represents a measurement curve of the tightening torque Ci in the time t characteristic of a mechanical equilibrium breaking key. The curve has two consecutive peaks 301 and 303, separated by a valley shape 305. When the setpoint torque determined by the compression of the spring 61 is reached, the key undergoes a break in mechanical equilibrium defining the trigger. The valley form 305 corresponds to the breakage of mechanical equilibrium.

  Once the mechanical balance is broken, the operator does not instantly release the force exerted on the key. Over-torque, ie an additional torque to the setpoint torque is thus applied to the fixing element after the triggering of the key. The peak 303 corresponds to the measurement of the excess torque applied after the break in equilibrium, that is to say the maximum torque CM applied to the fastener once the equilibrium has been broken. The peak 301 corresponds to the measurement of the torque applied before the break in equilibrium.

  Figure 5 shows a flow diagram of a torque tightening cycle.

  A parameterization phase of the tool is performed before any operation. It consists of storing an identification number of the tool, predetermining a first low measurement threshold CO, a second low measurement threshold C1 and initializing the number of clamping cycles.

  The key has a slow sampling standby mode 401. During the slow sampling, a measurement Ci 403 is carried out.

  This measurement Ci is stored and compared 405 to the first predetermined low threshold CO.

  If the measurement Ci is below the CO threshold, the sleep mode is kept with slow sampling.

  If the measurement Ci is greater than the threshold CO, the key then goes into 10 work mode 407 fast sampling.

  The microcontroller stores in a memory 409 a value of the maximum torque CM equal to the threshold value CO.

  During the clamping phase, the microcontroller continuously samples the voltage of the gauges 410 and compares the measurement value Ci to the maximum torque value CM. The microcontroller retains the highest value. The value of the measured maximum torque CM is thus stored in a memory 413.

  The stored value is then compared 415 to the second predetermined lower threshold C1.

  If the value Ci is greater than the threshold Cl, the working mode is maintained with a fast sampling.

  If the value Ci is below the threshold Cl, the microcontroller executes a mechanical equilibrium break presence test 417. If the latter test is negative, the standby mode is reestablished.

  If the presence test is positive, the microcontroller increments the number of cycles 419. A positive presence test conditions the transmission 421 of one or more information relating to the clamping sequence, such as the presence of the mechanical equilibrium break. and / or the maximum torque value CM, an identifier number of the tool, the number of the cycle.

  The mechanical equilibrium break detection is performed by analyzing the specific waveform created by the sudden change in the resistance of the gauges at the moment of tripping.

  The variation of the gauge voltage is in the form of a pulse whose relaxation time is characterized by the natural frequency of the test body. This relaxation time is fixed because it is linked to the accuracy of the mechanical equilibrium break.

  Figure 6a shows a flowchart of a first mode of detecting the mechanical equilibrium break.

  The microcontroller samples 501 the output voltage of the measuring means of the gauges. A computer 215 performs a derivation calculation dCi / dt of the output voltage Ci with respect to the time t and stores 503 the value of this derivative in a memory m.

  The computer 215 compares 505 the value of the calculated derivative m to a predetermined slope value mO.

  If the calculated value m is less than the predetermined value of slope m0, the computer 215 performs a new calculation of derivative on the following sampling.

  If the calculated value m is greater than the predetermined value of slope mO, the microcontroller provides a mechanical equilibrium break presence information. After digital-to-analog conversion, a trip presence signal can be transmitted 507.

  FIG. 6b presents a flowchart of a second mode of detection of the mechanical equilibrium break.

  The microcontroller samples 600 the output voltage of the measuring means of the gauges. A first curve 601 for measuring the tightening torque Ci as a function of time t is stored.

  A second curve 602, identical to the first curve 601, is stored with a delta offset t, positive and low, in time t.

  A calculator performs a test of identifying the presence of an intersection 305 'between the first 601 and the second curve 602.

  If the response to this test is positive, the mechanical equilibrium break 305 'is present. The microcontroller provides information of presence of breakage of mechanical equilibrium. After digital-to-analog conversion, a trip or break-off presence signal can be transmitted 607 If the response to this test is negative, the microcontroller continues sampling 600.

  FIG. 4b represents a first curve 601 for measuring the tightening torque Ci in time t. The first curve 601 has a first peak 301 'characteristic of a trigger key.

  The second constructed curve 602 has a peak 301 ", itself shifted by a delta interval t in time.

  The intersection 305 'of the first 601 and second 602 curves defines the calculated instant of the triggering or breaking of mechanical equilibrium.

  We understand that the detection of the breakage of mechanical equilibrium is essential to count the number of cycles performed by a production operator and thus improve traceability.

  The transmission may be a wireless link transmission 217 to a control equipment 219 either outside or integrated in the key. In this case, it may be a radio frequency link in the 869Mhz ISM band. The previous wireless transmission can be replaced by wired link transmission.

  The value of the maximum torque measured after breaking the mechanical balance of the key can then be displayed on a screen of the control equipment.

  The detection method according to the invention allows other steps such as, successively, the measurement of the maximum torque after the break of mechanical equilibrium, the transmission of the measurement of the maximum torque after the breakdown of mechanical equilibrium and the display. the measurement value of the maximum torque after the break in mechanical equilibrium.

  The steps of the detection method may be preceded by a step of identifying the tool.

  It is understood that the invention applies particularly well to a torque wrench trigger, as described above, but it could also be suitable for other torque tools, for example a wrench or a screwdriver.

  The invention which has just been described makes it possible to make reliable the mechanical equilibrium breakage detection function, without any additional space requirement for a dynamometric tool.

Claims (16)

  1. Tool, in particular a mechanical torque wrench with manual torque application comprising mechanical means (3,7,63,64,65,67) capable of providing a predetermined torque to a drive part (5) intended to cooperate with a screw member for driving a fixing element, said mechanical means being in mechanical equilibrium under the action of biasing means (31,61) adapted, said mechanical means being releasable by breaking the mechanical balance, and means method for detecting the mechanical equilibrium break, characterized in that the mechanical equilibrium break detection means comprise measuring means (121) providing a signal corresponding to the measurement of the torque applied to the fastener, electronic processing means (201, 203, 205, 207) of said signal and calculation processing means (215) of data resulting from the electronic processing of said signal.   2. Torque tool according to claim 1 characterized in that the calculating means detect the breakage of mechanical equilibrium by calculation derivative (501,503,507) of the measurement value of the torque with respect to time.   3. Dynamometric tool according to claim 1, characterized in that the calculation means the breaking of mechanical equilibrium by calculation of intersection (600, 601, 602, 605, 607) of a first (601) and a second (602) curves, the first curve. representing the measurement value of the torque relative to time, the second curve being identical to the first with a shift (603) weak and positive in time.   4. Torque tool according to one of claims 1 to 3 characterized in that the electronic signal processing means (201,203,205,207) and the calculation means (215) are arranged inside the key.   5. Torque tool according to one of claims 1 to 4 characterized in that the key further comprises transmission means (209) of the measurement of the maximum tightening torque applied to the fastener to an external station (219). ) to the tool, and in that said station displays the maximum torque value applied to the fastener.   6. Torque tool according to one of claims 1 to 5 characterized in that the key further comprises means (209) for transmitting the measurement of the maximum tightening torque applied to the fastening element to receiving means ( 211; 213) integral with the tool, and in that said receiving means display information corresponding to the maximum torque value applied to the fastener.   7. Torque tool according to one of claims 1 to 6 characterized in that the measuring means comprise resistive sensitive elements (121).   8. Torque tool according to claim 7 characterized in that the measuring means comprise a plurality of strain gauges (121), mounted in a bridge.   9. Torque tool according to one of claims 1 to 8 characterized in that the tool is a trigger key.   10. Torque tool according to one of claims 1 to 8 characterized in that the tool is a key break.   11. Torque tool according to one of claims 1 to 8 characterized in that the tool is a screwdriver.   12. Torque tool according to one of claims 7 to 11 in combination with claim 5 characterized in that the information is transmitted by radio frequencies.   13. A method of detecting a mechanical equilibrium break during a manual torque tightening of a fastener element when the applied torque reaches a predetermined target torque, the method comprising the following steps: providing information corresponding to the measurement (501; 600) of the torque applied to the fixing element, the electronic processing of said information (201,203,205,207), the calculation processing (503,505; 601,602,305 ') of digital data resulting from the electronic processing of said information.   14. A method of detecting a mechanical equilibrium break during a manual tightening to the torque of a fastener element when the applied torque reaches a predetermined target torque characterized in that a supply step (413) of information corresponding to the measurement of the maximum torque applied to the fastener, after the equilibrium is broken, follows the calculation step according to claim 13.   15. A method of detecting mechanical failure of equilibrium during a manual tightening to the torque of a fastener element when the applied torque reaches a predetermined target torque characterized in that a transmission step (421) of the information corresponding to the measurement of the maximum torque applied to the fastener, after the equilibrium is broken, succeeds the supply step according to claim 14.   16. The method of claim 15 characterized in that the transmission step is a radio frequency transmission step.