WO2011116452A1 - Method for providing preestablished requirements to threaded fasteners and a digital torque converter tool assembly therefor - Google Patents
Method for providing preestablished requirements to threaded fasteners and a digital torque converter tool assembly therefor Download PDFInfo
- Publication number
- WO2011116452A1 WO2011116452A1 PCT/CA2010/000468 CA2010000468W WO2011116452A1 WO 2011116452 A1 WO2011116452 A1 WO 2011116452A1 CA 2010000468 W CA2010000468 W CA 2010000468W WO 2011116452 A1 WO2011116452 A1 WO 2011116452A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- digital
- tool assembly
- torque converter
- voltage
- converter tool
- Prior art date
Links
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
- B25B23/0078—Reaction arms
-
- 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
- B25B23/147—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for electrically operated wrenches or screwdrivers
Definitions
- a current sensor subassembly for providing an analog voltage signal corresponding to a current of the electrical subassembly for actuating the digital torque converter tool assembly, when the microcontroller subassembly for digital and analog signal processing detects that the current reaches a ultimate torque, the microcontroller subassembly for digital and analog signal processing shut-off the pulse width modulation and the voltage of the electrical subassembly for actuating the digital torque converter tool assembly;
- FIG. 3 A is a flowchart including the operational steps of the method for providing prerequired torques for fastening
- microcontroller 310 repeatedly switches a voltage of power supply 15, via motor switching circuit 320, on and off at high frequency, and, consequently produces an average voltage of electrical motor 110, dependent on an amount of motor switching circuit 320 on-time versus off-time;
- PWM pulse width modulation
- microcontroller 310 continues to monitor the current of electrical motor 110, and shuts-off the voltage supply to electrical motor 110, when the corresponding ultimate torque value is achieved;
- microcontroller 310 compares the measured current to a defined value; if the measured value is lower than the ultimate value, the PWM and the voltage of electric motor 110 is increased up to a defined maximum, until the ultimate torque/angle is/are reached, or the trigger 120 is released;
Abstract
The method and the assembly are so developed as to preliminarly determine, by calibration of the digital torque converter tool assembly, an interrelation between torques and corresponding currents, at an established voltage. During use, the torques are monitored by measuring their corresponding currents and reaching eventualy an ultimate torque with its corresponding current, the ultimate torque having a value corresponding to the one prerequired by the user. When required by the user, rotational increments of the threaded fasteners are monitored until an ultimate angular position is reached. The ultimate angular position corresponds to a calculated value of a required tension in the threaded fastener.
Description
Title: METHOD FOR PROVIDING PREESTABLISHED REQUIREMENTS TO THREADED FASTENERS AND A DIGITAL TORQUE CONVERTER TOOL ASSEMBLY THEREFOR.
I. BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to torque control systems for power driven rotating tools and, more particularly, to a method for providing pre-established torques and angles to threaded fasteners and a digital torque converter tool assembly therefor.
2. Description of the Prior Art
In order to install threaded fasteners, such as screws, bolts, nuts or the like, a power tool is used to apply the necessary torque. In installing a threaded fastener, it is usually required to tighten a threaded fastener until it is adequately tensioned, thereby insuring that the latter securely holds the workpiece(s). Generally, for threaded fasteners such as screws, the goal is fully seat the fastener into the material, regardless of the torque required. In critical bolting applications, the the required tension in the threaded fasteners is determined previously by engineering calculus, as to ensure that a certain attachment is firmly secured by one or more of those fasteners. The tension achieved in a threaded fastener is depending directly upon the applied torque, Therefore, it is necessary to tighten a fastener until an ultimate, preset torque has been achieved. An alternate method of reaching a torque, and then completing a rotational angle move, also determined by calculus, to achieve the ultimate tension is also employed in many critical applications. Ending the tightening of a threaded fastener, without applying enough tension, may
result in a non-secure attachment, which can sometimes lead to unexpected, grave consequences, especially in aircrafts, automobiles, bridges, pressure vessels, etc. On the other hand, applying an excessive tension during the tightening of a threaded fastener may damage the latter and/or the workpiece(s).
Attempts have been made in the past to develop power tools with preset torques. Several United States patents have addressed this issue. For example, United States Patent No. 7,112,934, dated Sep. 26, 2006 and granted to Gilmore for an "ELECTRICAL POWER TOOL HAVING MOTOR CONTROL CIRCUIT FOR PROVIDING CONTROL OVER THE TORQUE OUTPUT OF THE POWER TOOL." This patent describes a portable power tool having an output spindle, an electric motor for driving the output spindle and a control system for controlling the operation of the motor. The control system includes a power source and a power switching device
interconnecting the power source to the motor for applying a constant frequency PWM drive signal from the power source to the motor. Furthermore, the control system includes a controller for controlling the power switching device and monitoring at least one operating characteristic of the power tool and reducing the frequency of the PWM drive signal in response to a
predetermined change in the operating characteristic. Thus, the power tool enters a ratchet mode of operation.
The foregoing tool has several disadvantages when applied to bolting applications requiring precise, controlled tension. Among them, the fact the ultimate torque is not calibrated, and the speed is adjustable by the user, user's adjustment would cause deviations of the ultimate torque from a preestablished torque. Also, the invention does not provide a means for precise, controlled angular position. Furthermore, the ratcheting mode can apply excess torque to the fastener.
II. SUMMARY OF THE INVENTION
Based on the state of the art, there is a need for an improved method and power tool that surmounts the existing disadvantages.
Thus, it is an objective of the present invention to devise a reliable method and a tool therefor which is precise and provides reproducible results.
It is another objective to provide ultimate torque, digitally indicated in engineering units ( for example,Ft Lbs, or NM), achieved by storing calibration values which relate motor current to ultimate torque.
It is yet another objective of the present invention to use ultimate torque to establish desired ultimate torque and shut tool off.
It is still another objective of the present invention to use Speed Measurement to verify current measurements in order to determine whether valid ultimate current has been reached; variable characteristics in fasteners may cause measurement spikes which in some cases could falsley indicate that a ultimate value has been reached.
Broadly stating, the method for providing prerequired torques to threaded fasteners, according to the present invention, comprises the following operational steps:
- preliminarly determining by calibration of a digital torque converter tool assembly, an interrelation between torques and corresponding currents at an established voltage;
- supplying power, during normal use use of the digital torque converter tool assembly, to
produce the torques;
- monitoring the torques, during the normal use of the digital torque converter tool assembly, by measuring their corresponding currents and reaching eventually an ultimate torque with its corresponding current,the ultimate torque having such a value as one prerequired by a user;
- then, monitoring, when required by the user, rotational increments of the threaded fasteners for the purpose of successively determining positionally rotational angles of the threaded fasteners until reaching an ultimate angular position, as one prerequired by user and adapted to correspond to a calculated value of a required tension in the threaded fastener; and
- ceasing supplying the power to the digital torque converter tool assembly;
whereby,
- precision and reproducibility are assured during use of the digital torque converter tool assembly established by initial calibration so that a required torque is obtained by supply voltage regulation and motor current measurement, thereby subjectivity of the user in attaining the required torque is avoided;
- providing a first zone during fastening, characterized by a controlled voltage during an initial supply of the power for producing the torques, and in order to minimize an inrush current during the first zone;
- providing a second zone during fastening, characterized by a continuously controlled voltage until reaching the ultimate torque, so that precise accuracy and reproducibility are achieved, as pre-established initially by calibration; and
- providing, a third zone during fastening, allowing an angular controlled position of the threaded fastener, in order to obtain a prerequired tension in a joint assembly comprising the threaded
fastener.
Broadly stating, the digital torque converter tool assembly, according to the present invention, comprises, in combination,
- a subassembly for supplying power;
- an electrical subassembly for actuating the digital torque converter tool assembly;
- a mechanical subassembly for converting torques supplied by the electrical subassembly for actuating the digital torque converter tool assembly; and
- a microcontroller subassembly for digital and analog signal processing, used for selecting and controlling the electrical subassembly for actuating the digital torque converter tool assembly up to a desired ultimatum value, which is accurate and reproducible during successive operations, a memory to store user's settings and calibration values being provided for this purpose;
- a motor switching circuit subassembly for precisely control a voltage of the electrical subassembly for actuating the digital torque converter tool assembly and a shut off of the mechanical subassembly for converting torques to a ultimate torque and/or angular position; the motor switching circuit subassembly for precisely control a voltage of the electrical subassembly for actuating the digital torque converter tool assembly and a shut off of the mechanical subassembly for converting torques at a desired torque and/or a ultimate angular position, being interconnected to the microcontroller subassembly for digital and analog signal processing by means of pulse width modulation,
the microcontroller subassembly for digital and analog signal processing repeatedly switch the supply voltage, via the motor switching circuit subassembly for precisely control a voltage, on
and off at high frequency, consequently producing an average voltage of the electrical subassembly for actuating the digital torque converter tool assembly, dependent on the amount of on-time versus off-time;
whereby, variations in a supply voltage directly affect a voltage of the electrical subassembly for actuating the digital torque converter tool assembly and increase or decrease an output torque; a change in the output torque creating an offset error from stored calibration values, the microcontroller subassembly for digital and analog signal processing; monitoring and responding to changes in the supplied voltage by adjusting the subassembly of pulse width modulation and the voltage of the electrical subassembly for actuating the digital torque converter tool assembly, for the purpose of achieving accurate and reproducible torques, the voltage of the electrical subassembly for actuating the digital torque converter tool assembly being so controlled within an acceptable range;
- a current sensor subassembly for providing an analog voltage signal corresponding to a current of the electrical subassembly for actuating the digital torque converter tool assembly, when the microcontroller subassembly for digital and analog signal processing detects that the current reaches a ultimate torque, the microcontroller subassembly for digital and analog signal processing shut-off the pulse width modulation and the voltage of the electrical subassembly for actuating the digital torque converter tool assembly;
- a motor supply voltage sensor subassembly for providing a signal proportional to the supply voltage;
the microcontroller subassembly for digital and analog signal processing being used for monitoring the supply voltage and for adjusting the pulse width modulation and the average
voltage of the electrical subassembly for actuating the digital torque converter tool assembly;
- a speed sensor subassembly for providing a digital pulse when magnets, mounted on a shaft of the electrical subassembly for actuating the digital torque converter tool assembly, pass across the speed sensor subassembly for providing the digital pulse, the digital pulse representing a rotation angular frequency of the electrical means for actuating the digital torque converter tool assembly;
- a position sensor subassembly for indicating a relative rotation of the shaft of the electrical subassembly for actuating the digital torque converter tool assembly in order to control an angular displacement from a zeroed position at a preset torque;
- a trigger subassembly for supplying voltage to the electrical subassembly for actuating the digital torque converter tool assembly, the trigger subassembly for supplying voltage being simultaneously interconnected to the power supply and to the microcontroller subassembly for digital and analog signal processing, so that, when the trigger subassembly for supplying voltage is pressed and held,
the microcontroller subassembly for digital and analog signal processing detects the supply voltage of the electrical subassembly for actuating the digital torque converter tool assembly as an analog signal for the purpose of starting and adjusting the pulse width modulation;
- a keypad subassembly, connected to the microcontroller subassembly for digital and analog signal processing, for changing ultimate torque/angle position and calibration values and for accessing datalog and to diagnose several functions of the digital torque converter tool assembly;
- a digital display subassembly, connected to the microcontroller subassembly for digital and
analog signal processing, for displaying user's selected ultimate torque/angle position, actual measured values, tool status, torque/angle cycle status, calibration values, datalog and diagnostic screens;
and
- a direction control subassembly for controlling both directions of the electrical subassembly for actuating the digital torque converter tool assembly.
ΙΠ. BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side prospective view of digital torque converter assembly;
FIG. 2 is a diagrammatic representation of a digital controller of digital torque converter
assembly of FIG.1;
FIG. 3 A is a flowchart including the operational steps of the method for providing prerequired torques for fastening;
FIG. 3B is a flowchart including the operational steps of the method for providing prerequired angular positions;
FIG. 4 is diagram illustrating the relationship between actual torques and corresponding motor currents, while an electrical motor voltage is maintained constant;
FIG. 5 is a diagram illustrating a variation in motor output torque in relation to motor speed; and FIG. 6 is a diagram illustrating a variation in time of torque/angular position during a fastening operation.
IV. DESCRIPTION OF THE PREFERRED EMBODIMENTS
Broadly describing, with reference to FIGS.l to 6, a digital torque converter tool assembly 10,
according to the present invention, comprises, in combination,
- a power supply subassembly 15, in the form of DC power supply, from a battery or converted from AC source (not shown);
- an electrical motor subassembly 100;
- a mechanical torque converter subassembly 200 coupled to electrical motor subassembly 100 and used for reducing an angular velocity supplied by electrical motor subassembly 100 and, thereby, to deliver an increased torque output; and
- a digital controller subassembly 300 mounted on top of electrical motor subassembly 100 and used for digitally achieving an ultimate torque value and an ultimate angular positional value.
Describing now in detail, digital torque converter tool assembly 10 comprises:
- electrical motor subassembly 100 incorporated in a pistol grip encasing 105 and forming an unit, of the type sold for different inputs by METABO, under the tradename SBE. Electrical motor subassembly 100 includes an electrical motor 110 of DC brush or brushless type, combined with an electro-mechanical switch 120 and an electro-mechanical direction-change device 130;
- mechanical torque converter subassembly 200 of conventional planetary gear type, coaxially and forwardly coupled to the output shaft (not shown) of electrical motor 110; mechanical torque converter subassembly 200 is provided with a counter-reaction arm 210 and its front is used with a socket 220 (not shown) to engage a fastener (also not shown);
- digital controller subassembly 300 incorporating
- a microcontroller 310 for digital and analog signal processing, used for achieving the ultimate torque value and ultimate angular position value, both preselected by a user, which
values are accurately reproducible during successive operations, a memory to store the user's preselected values and calibration values being, for this purpose, provided;
microcontroller 310 used in the present embodiment is an 8-bit microcomputer of the type made by Silicon Industries, under the name of C8051 ;
- a motor switching circuit 320 to precisely control a voltage of electrical motor 110 and shut off mechanical torque converter subassembly 200, at an ultimate torque value (See C on FIG. 6) and an ultimate, angular positional value (See E on FIG. 6);
motor switching circuit 320, used in the present embodiment, is an electrical switch, such as a MOSFET, made by ST, interconnected to microcontroller 310;
by means of pulse width modulation, or PWM, microcontroller 310 repeatedly switches a voltage of power supply 15, via motor switching circuit 320, on and off at high frequency, and, consequently produces an average voltage of electrical motor 110, dependent on an amount of motor switching circuit 320 on-time versus off-time;
whereby, variations in the voltages of power supply 15 directly affect the voltage and speed of electrical motor 110, thereby increasing or decreasing the motor output torque (see FIG. 5), and so modifies the ultimate torque;
a change in output torque creates an offset error from the stored calibration values;
microcontroller 310 monitors and responds to changes in the voltage of power supply 15, by adjusting the PWM and the voltage of electrical motor 110; for the purpose of achieving accurate, reproducible torques, the voltage of electrical motor 110 is maintained within an acceptable range;
- a current sensor 330 of shunt resistor type, in series with electrical motor 110 and
interconnected to microcontroller 310, produces an analog voltage signal, directly proportional to the current of electrical motor 110;
the currents of electrical motor 110 corresponds to torques measured in standard engineering units, and calibrated therfore (see FIG. 4);
when microcontroller 310 detects that the calibrated current, corresponding to the ultimate torque value, is achieved, microcontroller 310 shuts-off the voltage supply to electrical motor 110 (see diagram of FIG. 6);
in a variant, microcontroller 310 reduces the voltage of electrical motor 110, to a fixed lower value, near the ultimate torque value; this is done in order to reduce the speed and, as a result, inertia of rotating parts of digital torque converter tool assembly 10 and, by virtue of this, improve accurate reproducibility of the ultimate torque value;
according to this variant, after the voltage to electrical motor 110 is reduced,
microcontroller 310 continues to monitor the current of electrical motor 110, and shuts-off the voltage supply to electrical motor 110, when the corresponding ultimate torque value is achieved;
in a variant of the above embodiment, use is made of a strain gauge sensor(s) (not shown), combined with mechanical torque converter subassembly 200 and interconnected to the microcontoller 310; the torsional deflection in the strain gauge sensor(s) produces an analog voltage signal, corresponding to ultimate torque, measured in standard engineering units, and calibrated therfore;
- a motor supply voltage sensor 340 /in the form of a resistive voltage divider, or an integrated chip (IC), as one made by Linear Devices/ interconnected to microcontroller 310, produces a
signal proportional to supplied voltage: microcontroller 310 monitors the supply voltage, and as a result, adjusts PWM and, thus, the average voltage of electric motor 110, as previously described;
in a variant, microcontroller 310 adjusts the current shut-off value, in response to variations in the power supply voltage, in order to achieve an accurate, reproducible ultimate torque;
- a speed sensor 350, in the form of a Hall Effect sensor, interconnected to microcontroller 310, produces digital pulses when magnets, that are mounted on the shaft (not shown) of electric motor 110, traverses speed sensor 350; the digital pulses correspond to
speed (rpm) of electrical motor 110;
in a variant, a different speed sensor 350 /in the form of a resistive voltage divider, or an integrated chip (IC) as one made by Linear Devices/, interconnected to electrical motor 110 and to microcontroller 310, provides a signal reference of electrical's motor 110 back electromotive force (Back EMF); as those skilled in the art are aware, Back EMF is dependant on the speed of electrical motor 110;
speed sensor 350, in one variant, indicates relative rotation of electrical motor's 110 shaft, used for controlling angular displacement from an ultimate torque;
in another variant, any position feedback device, such as an encoder, potentiometer etc. may be used;
- a trigger 120 /in the form of an electro-mechanical, momentary switch, of the type made by Capax/ interconnected to power supply 15 and to controller subassembly 300, provides the supply voltage to motor switching circuit 320 by means of an electrical contact /when trigger 120 is pressed and held/; the microcontroller 310 detects the digital signal of trigger 120 and
the analog signal of motor supply voltage sensor 340, for the purpose of adjusting the P WM to supply voltage to electrical motor 110, as previously described, (See A and D on FIG. 6); as those skilled in the art know, electrical motor 110 will draw a significantly high inrush current, when voltage is first applied (See B on FIG. 6); this high inrush current can cause the microcontroller 310 to erroneously detect that the ultimate torque is reached;
when trigger 120 is pressed and held, microcontroller 310 sets the PWM (See A and D on FIG. 6) and the average voltage of electric motor 110 to an initial value for a defined time, for the motor inrush current to be reduced, after the inrush current time has elapsed;
microcontroller 310 compares the measured current to a defined value; if the measured value is lower than the ultimate value, the PWM and the voltage of electric motor 110 is increased up to a defined maximum, until the ultimate torque/angle is/are reached, or the trigger 120 is released;
- a keypad 370, in the form of multiple discrete push-buttons, of membrane type, as the one made by Padtech Industries, is interconnected with microcontroller 310 and employed by the user to change the ultimate torque value, change calibration values and access datalog and diagnostic functions;
- a digital display 380 /of LCD or OLED type, made by 4D Systems/ interconnected to microcontroller 310, displays user's ultimate torque and ultimate angle values
(in standard engineering units), tool status, calibration values, datalog and diagnostic information; and
- a direction control 130, in the form of a electro-mechanical switch, operated by the user and interconnected to the motor switiching circuit 320, controls the polarity of voltage of
electrical motor 110, thereby changing the direction of rotation.
The method for providing prerequired torques to threaded fasteners, according to the present invention, comprises the following operational steps:
- preliminarly determining by calibration of a digital torque converter tool assembly, an interrelation between torques and corresponding currents at an established voltage;
- supplying power, during normal use of the digital torque converter tool assembly, to produce the torques;
- monitoring the torques, during the normal use of the digital torque converter tool assembly, by measuring their corresponding currents and reaching eventually an ultimate torque with its corresponding current,the ultimate torque having such a value as one prerequired by a user;
- then, monitoring, when required by the user, rotational increments of the threaded fasteners for the purpose of successively determining positionally rotational angles of the threaded fasteners until reaching an ultimate angular position, as one prerequired by user and adapted to correspond to a calculated value of a required tension in the threaded fastener;
- ceasing supplying the power to the digital torque converter tool assembly;
whereby,
- precision and reproducibility are assured during use of the digital torque converter tool assembly established by initial calibration so that a required torque is obtained by supply voltage regulation and motor current measurement, thereby subjectivity of the user in attaining the required torque is avoided;
- providing a first zone during fastening, characterized by a controlled voltage during an initial supply of the power for producing the torques, and in order to minimize an inrush current during the first zone;
- providing a second zone during fastening, characterized by a continuously controlled voltage until reaching the ultimate torque, so that precise accuracy and reproducibility are achieved, as pre-established initially by calibration; and
- providing, a third zone during fastening, allowing an angular controlled position of the threaded fastener., in order to obtain a prerequired tension in a joint assembly comprising the threaded fastener.
Operation of the tool
The user will select an ultimate torque value and, optionally, select as well an ultimatum angle value. The user, by means of digital display 380 and keypad 370, selects the ultimatum values, as displayed in standard engineering units, by incrementing or decrementing the values, via keypad 370. The user may also select the desired standard engineering units for torque, for example NM, or ft lbs, etc.
Digital display 380 also indicates the operational readiness of digital torque converter tool assembly 10.
Under normal operation, microcontroller 310, by means of digital display 380, will indicate "Ready" status when digital torque converter tool assembly 10 is idle. Microcontroller 310 will indicate "Torque Pass", when the ultimate torque has been reached, and "Angle Pass", if the ultimate angle has been reached. Microcontroller 310 will indicate a "Fail" if a torque cycle is
stopped by means of releasing the trigger 120, before the ultimate torque value is reached, or electrical motor 110 is reversed before the ultimate angle is reached. If a fault condition occurs at any time, the fault will be indicated, and microcontroller 310 stops electrical motor 110.
Depending on the fault severity, microcontroller 310, may hinder further operation of the tool until a full power cycle.
As seen in Fig 3 A, when digital torque converter tool assembly 10 is in the "Ready" status and, the user has selected the ultimatum values, the fastening operation occurs by pressing and holding trigger 120 ; thus, by means of motor switching circuit 320, microcontroller 310 applies an initial voltage to electrical motor 110. The motor voltage is held for a period of time to allow the inrush current to subside (See B on FIG. 6). Microcontroller 310 then increases the voltage to a calibrated value, by adjusting the PWM of motor switching circuit 320. It can be appreciated by those trained in the art that variations in voltage of electrical motor 110, cause variation in speed and torque of electrical motor 110. If the voltage of electrical motor 110 differ from the voltage calibrated value, the relationship between motor current and torque (FIG 4), will differ from the calibrated values; thus the "ultimate torque" is not accurate, since it does not correspond to the calibrated value. The motor supply voltage sensor 340, connected to, and measured by the microcontroller 310, is compared to the calibrated voltage value. Microcontroller 310 adjusts the voltage of the electrical motor 110, to match the calibrated voltage value within a pre-established acceptable range.
As those trained in the art will appreciate, after voltage is applied to electrical motor 110, and the inrush current has subsided, the current of the electrical motor 110 will be directly related to the
torque load (Fig 4); during the increase of the voltage towards a calibrated value, the difference between the former and the latter causes a lower motor output torque (see FIG. 5) with respect to a preestablished calibration value; thus, microcontroller 310 adjusts proportionally the current shut-off value to correspond to ultimate torque /during this period of voltage increase/.
Microcontroller 310, interconnected to the current sensor 330, compares the measured value to calibrated value corresponding to the ultimate torque. When the measured value reaches the ultimate torque, the microcontroller 310 shuts off the voltage to electrical motor 110. If the user has selected ultimate torque value only, and no ultimate angle, the microcontroller 310 will not re-apply motor voltage /until the trigger 120 has been released for a period of time/.
In general it is known that dynamic friction factors, during tightening of a fastener assembly, cause critical variations in the current of the electrical motor 110. These critical variations vary in amplitude, but are generally short in duration. Microcontroller 310, by means of multiple successive measurements and by averaging, filters the critical variations, minimizing
measurement error of current of electrical motor 110. These measurement errors will otherwise incorrectly indicate that ultimate torque has been reached or exceeded. For critical variations in current of the electrical motor 110, that are longer in duration and cannot be practically filtered by the microcontroller 310, speed is used to filter the critical variations of current of the electrical motor 110. Microcontroller 310, interconnected to speed sensor 350, measures the speed of electrical motor 110, and compares it to a pre-established calibrated value. If the measured speed is above the pre-established calibrated value, the current measurements are temporarily ignored. If the measured speed is at or below the pre-established calibrated value,
the current measurements are used to establish ultimate torque.
Referring now to B in Figs 3 A and 3B, if the user has selected an ultimate torque value, and an ultimate angle value, then, after reaching the ultimate torque value, microcontroller 310 will zero the position. When the trigger 120 is pressed and held, microcontroller 310 applies a pre- established by calibration voltage to the electrical motor 110. The microcontroller 310, interconnected to speed sensor 350, measures the variation in angular position. The
microcontroller 310 compares the variation of angular position with respect to the ultimate value, and when reached microcontroller 310 shuts off voltage of electrical motor 110 (See D and E on FIG 6).
During the angular position move, microcontroller 310 continues to monitor the current sensor 330, thus the torque (to protect the digital torque converter tool assembly 10 against damage. If the measured torque exceeds a saftey limit, microcontroller 310 shuts off the voltage of electrical motor 110. The microcontroller 310 will not re-apply voltage to the electrical motor 110, until the trigger 120 has been released.
Claims
1. A method for providing prerequired torques to threaded fasteners comprising the following operational steps:
- preliminarly determining by calibration of a digital torque converter tool assembly, an interrelation between torques and corresponding currents at an established voltage;
- supplying power, during normal use of said digital torque converter tool assembly, to produce said torques;
- monitoring said torques, during said normal use of said digital torque converter tool assembly, by measuring their corresponding currents and reaching eventually an ultimate torque with its corresponding current, said ultimate torque having such a value as one prerequired by a user;
- then, monitoring, when required by said user, rotational increments of said threaded fasteners for the purpose of successively determining positionally rotational angles of said threaded fasteners until reaching an ultimate angular position, as one prerequired by user and adapted to correspond to a calculated value of a required tension in said threaded fastener;
- ceasing supplying said power to said digital torque converter tool assembly;
whereby,
- precision and reproducibility are assured during use of said digital torque converter tool assembly established by initial calibration so that a required torque is obtained by supply voltage regulation and motor current measurement, thereby subjectivity of the user in attaining said required torque is avoided;
- providing a first zone during fastening, characterized by a controlled voltage during an initial supply of said power for producing said torques, and in order to minimize an inrush current during said first zone;
- providing a second zone during fastening, characterized by a continuously controlled voltage until reaching said ultimate torque, so that precise accuracy and reproducibility are achieved as pre-established initially by calibration;
- providing, a third zone during fastening, allowing an angular controlled position of said threaded fastener, in order to obtain a prerequired tension in a joint assembly comprising said threaded fastener.
2. A digital torque converter tool assembly comprising, in combination,
- means for supplying power;
- electrical means for actuating said digital torque converter tool assembly;
- mechanical means for converting torques supplied by said electrical means for actuating said digital torque converter tool assembly; and
- microcontroller means for digital and analog signal'processing, used for selecting and controlling said electrical means for actuating said digital torque converter tool assembly up to a desired ultimate value, which is accurate and reproducible during successive operations, a memory to store user's settings and calibration values being provided for this purpose,;
- motor switching circuit means for precisely control a voltage of said electrical means for actuating said digital torque converter tool assembly and a shut off of said mechanical means for converting torques to a ultimate torque and/or angular position; said motor switching circuit means for precisely control a voltage of said electrical means for actuating said digital torque converter tool assembly and a shut off of said mechanical means for converting torques at a desired torque and/or a ultimate angular position, being interconnected to said microcontroller means for digital and analog signal processing by means of pulse width modulation; said microcontroller means for digital and analog signal processing repeatedly switch the supply voltage, via said motor switching circuit means for precisely control a voltage, on and off at high frequency, consequently producing an average voltage of said electrical means for actuating said digital torque converter tool assembly, dependent on the amount of on-time versus off-time;
whereby, variations in a supply voltage directly affect a voltage of said electrical means for actuating said digital torque converter tool assembly and increase or decrease an output torque; a change in the output torque creating an offset error from stored calibration values, said microcontroller means for digital and analog signal processing; monitoring and responding to changes in the supplied voltage by adjusting said means of pulse width modulation and the voltage of said electrical means for actuating said digital torque converter tool assembly, for the purpose of achieving accurate and reproducible torques, the voltage of said electrical means for actuating said digital torque converter tool assembly being so controlled within an acceptable range;
- current sensor means for providing an analog voltage signal corresponding to a current of said electrical means for actuating said digital torque converter tool assembly, when said
microcontroller means for digital and analog signal processing detect that the current reaches a ultimate torque, said microcontroller means for digital and analog signal processing shut-off said pulse width modulation and the voltage of said electrical means for actuating said digital torque converter tool assembly;
- motor supply voltage sensor means for providing a signal proportional to the supply voltage; said microcontroller means for digital and analog signal processing being used for monitoring the supply voltage and for adjusting said pulse width modulation and said average voltage of said electrical means for actuating said digital torque converter tool assembly;
■ speed sensor means for providing a digital pulse when magnets, mounted on a shaft of said electrical means for actuating said digital torque converter tool assembly, pass across said speed sensor means for providing said digital pulse, said digital pulse representing a rotation angular frequency of said electrical means for actuating said digital torque converter tool assembly;
■ position sensor means for indicating a relative rotation of said shaft of said electrical means for actuating said digital torque converter tool assembly in order to control an angular displacement from a zeroed position at a preset torque;
■ trigger means for supplying voltage to said electrical means for actuating said digital torque converter tool assembly, said trigger means for supplying voltage being simultaneously interconnected to said power supply and to said microcontroller means for digital and analog signal processing, so that, when said trigger means for supplying voltage are pressed and held, said microcontroller means for digital and analog signal processing detect said supply voltage of said electrical means for actuating said digital torque converter tool assembly as an analog signal for the purpose of starting and adjusting said pulse width modulation;
■ keypad means, connected to said microcontroller means for digital and analog signal processing, for changing ultimate torque/angle position and calibration values and for accessing datalog and to diagnose several functions of said digital torque converter tool assembly;
■ digital display means, connected to said microcontroller means for digital and analog signal processing, for displaying user's selected ultimate torque/angle position in standard_engineering units, actual measured values, tool status, torque/angle cycle status, calibration values, datalog and diagnostic screens;
and
- direction control means for controlling both directions of said electrical means for actuating said digital torque converter tool assembly.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CA2010/000468 WO2011116452A1 (en) | 2010-03-26 | 2010-03-26 | Method for providing preestablished requirements to threaded fasteners and a digital torque converter tool assembly therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CA2010/000468 WO2011116452A1 (en) | 2010-03-26 | 2010-03-26 | Method for providing preestablished requirements to threaded fasteners and a digital torque converter tool assembly therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2011116452A1 true WO2011116452A1 (en) | 2011-09-29 |
Family
ID=44672398
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/CA2010/000468 WO2011116452A1 (en) | 2010-03-26 | 2010-03-26 | Method for providing preestablished requirements to threaded fasteners and a digital torque converter tool assembly therefor |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO2011116452A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2937180A1 (en) | 2014-04-24 | 2015-10-28 | Etablissements Georges Renault | System for controlling an industrial tool by modifying the control signals during usage faults |
| JP5964521B2 (en) * | 2013-12-27 | 2016-08-03 | 株式会社 エニイワイヤ | Torque management system for electric drivers |
| WO2017001175A1 (en) * | 2015-06-30 | 2017-01-05 | Atlas Copco Industrial Technique Ab | Method and a power tool for error proof screw joint tightening |
| EP2633955A3 (en) * | 2012-03-01 | 2017-06-07 | STAHLWILLE Eduard Wille GmbH & Co. KG | Torque tool with display |
| CN115356035A (en) * | 2022-10-20 | 2022-11-18 | 华东交通大学 | Bolt tightening torque detection system and detection method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5154242A (en) * | 1990-08-28 | 1992-10-13 | Matsushita Electric Works, Ltd. | Power tools with multi-stage tightening torque control |
| US7328752B2 (en) * | 1999-04-29 | 2008-02-12 | Gass Stephen F | Power tools |
-
2010
- 2010-03-26 WO PCT/CA2010/000468 patent/WO2011116452A1/en active Application Filing
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5154242A (en) * | 1990-08-28 | 1992-10-13 | Matsushita Electric Works, Ltd. | Power tools with multi-stage tightening torque control |
| US7328752B2 (en) * | 1999-04-29 | 2008-02-12 | Gass Stephen F | Power tools |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2633955A3 (en) * | 2012-03-01 | 2017-06-07 | STAHLWILLE Eduard Wille GmbH & Co. KG | Torque tool with display |
| JP5964521B2 (en) * | 2013-12-27 | 2016-08-03 | 株式会社 エニイワイヤ | Torque management system for electric drivers |
| EP2937180A1 (en) | 2014-04-24 | 2015-10-28 | Etablissements Georges Renault | System for controlling an industrial tool by modifying the control signals during usage faults |
| FR3020301A1 (en) * | 2014-04-24 | 2015-10-30 | Renault Georges Ets | SYSTEM FOR CONTROLLING AN INDISTRITIC TOOL BY MODIFYING CONTROL SIGNALS DURING USE DEFECTS |
| WO2017001175A1 (en) * | 2015-06-30 | 2017-01-05 | Atlas Copco Industrial Technique Ab | Method and a power tool for error proof screw joint tightening |
| CN107810091A (en) * | 2015-06-30 | 2018-03-16 | 阿特拉斯·科普柯工业技术公司 | The method and power tool of fastening are threadedly engaged for mistake proofing |
| US10843315B2 (en) | 2015-06-30 | 2020-11-24 | Atlas Copco Industrial Technique Ab | Method and a power tool for error proof screw joint tightening |
| CN115356035A (en) * | 2022-10-20 | 2022-11-18 | 华东交通大学 | Bolt tightening torque detection system and detection method |
| CN115356035B (en) * | 2022-10-20 | 2023-02-07 | 华东交通大学 | Bolt tightening torque detection system and detection method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2535299C (en) | Method for applying preset torques to threaded fasteners and a power tool therefor | |
| US7770658B2 (en) | Control method and control unit for impact type screw fastening device | |
| US6516896B1 (en) | Torque-applying tool and control therefor | |
| EP3254809B1 (en) | Method for applying torque and electric torque fastening system | |
| JP2957838B2 (en) | Apparatus and method for compensating torque overshoot of power tool | |
| US7556103B2 (en) | Tightening tool and tightening tool management system | |
| WO2011116452A1 (en) | Method for providing preestablished requirements to threaded fasteners and a digital torque converter tool assembly therefor | |
| CN110087836B (en) | Impact rotary tool | |
| JP2005118910A (en) | Impact rotary tool | |
| EP3272463B1 (en) | Impact rotary tool | |
| JPH09503377A (en) | Electric motor with means for torque detection | |
| US10661418B2 (en) | Threaded member tightening tool and drive time setting method for threaded member tightening tool | |
| JPH11138459A (en) | Impact screw fastening method and its device | |
| JP2002064996A (en) | Method and device for controlling stepping motor and motor driver | |
| US20150290784A1 (en) | Method for controlling a screwdriver and screwdriver | |
| JP6452399B2 (en) | Control device for electric drive equipment | |
| JP2023538246A (en) | Electric screwdriver with clutch setting sensor | |
| KR100594795B1 (en) | Bolt fastening method | |
| JPH0921712A (en) | Method of forming screw bond | |
| JP3037288B1 (en) | Bolt tightening torque control method | |
| JP2001062744A (en) | Electric tightening machine and tightening control method therewith | |
| JPH0451309B2 (en) | ||
| JP2001030123A (en) | Automatic screwing machine | |
| JPH0318138Y2 (en) | ||
| KR100242687B1 (en) | Torque controllable electric wrench and control device therefor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 10848149 Country of ref document: EP Kind code of ref document: A1 |
|
| NENP | Non-entry into the national phase |
Ref country code: DE |
|
| 122 | Ep: pct application non-entry in european phase |
Ref document number: 10848149 Country of ref document: EP Kind code of ref document: A1 |