Combined wrench and marking system

Self-contained, combined wrench and marking system, and method for installing a fitting and for automatically marking an installed fitting. The self-contained combined wrench and marking system has a wrench that may include a wrench head for rotating a fastener during a fastener tightening operation, a torque measuring mechanism for measuring a torque applied to the fastener during the fastener tightening operation, and an angle measuring mechanism for rotating the fastener to a preset angle during the fastener tightening operation. The self-contained combined wrench and marking system also has a marking system for automatically marking the fastener after the torque is applied to the fastener and after rotating the fastener to the preset angle.

BACKGROUND INFORMATION

The disclosure relates generally to a method and apparatus for installing fluid fittings and fasteners. More particularly, the present disclosure relates to a self-contained, combined wrench and marking system for installing and marking fluid fittings and fasteners, and to a method for installing and marking fluid fittings and fasteners.

An aircraft includes many movable structures, for example and without limitation, wing flaps, vertical fins and ailerons, that are operated hydraulically. Accordingly, a typical aircraft may include many hydraulic lines that extend throughout the aircraft and that are comprised of numerous line sections joined together by fluid fittings.

The fittings are assembled to the line sections using nuts, and it is important that the assembled structures be fluid-tight. In a typical procedure for installing a hydraulic line in an aircraft, a mechanic first loosely attaches one end of a fitting to a line section by hand-tightening the nut at the one end of the fitting, then stretches or compresses the line section so that the opposite end of the fitting can be attached to another line section, again by hand-tightening the nut at the opposite end of the fitting. The mechanic then further tightens the nuts, first at one end and then at the opposite end of the fitting. This process of alternately tightening the nuts at the ends of the fitting may be repeated two or three times until the nuts at both ends of the fitting are fully tightened.

A mechanic may install several hundred hydraulic fittings in a day, and to help ensure that all nuts and fittings have been properly tightened, it is often the practice to mark a nut and/or fitting after it has been fully tightened.

As a result of the process of alternately and repeatedly tightening the nuts at the opposite ends of a fitting, however, it is not uncommon that the mechanic might inadvertently fail to fully tighten the nut at one or both ends of a fitting, yet still mark the nuts as being fully tightened.

All fittings in a hydraulic line of an aircraft are subjected to leak-testing such that any nuts that may have been only hand-tightened or that were otherwise improperly installed will be identified and properly fastened. When a fitting fails leak-testing, however, it is necessary to clean the leaked aviation hydraulic fluid (e.g., Skydrol) from surrounding surfaces, and to then fully tighten any loose nuts prior to retesting of the fitting. In addition to being time consuming, the preferred cleaning agent used to clean the leaked aviation hydraulic fluid is Freon which is a hazardous material and may also cause damage to the surrounding surfaces that requires repair.

Thus, it would be desirable to minimize the number of fittings that fail during leak-testing.

The typical procedure for marking an assembled hydraulic joint requires the mechanic to apply a colored compound, (e.g., Inspection seal lacquer F925) by squeezing a small tube so that a stripe of the compound, sometimes referred to as a “torque stripe”, covers both the fitting and the nut. This procedure for marking an installed hydraulic joint may be unsatisfactory.

One problem, as indicated above, is that the mechanic may inadvertently mark a fitting that has not been fully tightened. Also, these manual marking procedures are time consuming and reduce productivity. Recognizing the inadequacies of manual marking procedures, a marking wrench was developed. The prior art marking wrench both tightens a fastener and then marks the tightened nut with ink to indicate that the nut has been tightened.

The prior art marking wrench, however, is still not fully satisfactory. For one thing, the marking wrench only marks the nut and not its mating fitting. It is desirable to have the mark cover both nut and fitting so that it would be known if someone loosened, or tampered with the nut. A misaligned mark on the nut and fitting surfaces flags this condition. The prior art marking wrench is also non-ratcheting which makes operation of the wrench rather slow. Furthermore, the prior art marking wrench contacts the nut with ink impregnated felt, but trials of this wrench found that the felt dried up, rendering its marking capability useless.

There is, accordingly, a need for a mechanism for installing fittings and fasteners in hydraulic lines in an aircraft and in other applications that will minimize fluid leaks during leak-testing, and that will also automatically mark installed fittings and fasteners after they have been properly installed.

SUMMARY

An embodiment of the disclosure provides a self-contained combined wrench and marking system. The self-contained combined wrench and marking system has a wrench that may include a wrench head for rotating a fastener during a fastener tightening operation, a torque measuring mechanism for measuring a torque applied to the fastener during the fastener tightening operation, and an angle measuring mechanism for rotating the fastener to a preset angle during the fastener tightening operation. The self-contained combined wrench and marking system also has a marking system for automatically marking the fastener after the torque is applied to the fastener and after rotating the fastener to the preset angle.

A further embodiment of the disclosure provides a self-contained combined wrench and marking system. The self-contained combined wrench and marking system has a wrench that may include a wrench head for tightening a fastener during a fastener tightening operation. The self-contained combined wrench and marking system also has a marking system for automatically marking the fastener after tightening the fastener. The marking system may include a marking fluid reservoir containing a marking fluid, a spray nozzle line connected to the marking fluid reservoir for receiving the marking fluid from the marking fluid reservoir, a replaceable gas cartridge containing a gas propellant, and a control valve for delivering the gas propellant from the replaceable gas cartridge to the spray nozzle line for spraying the marking fluid for marking the fastener.

A further embodiment of the disclosure provides a method for installing a fitting and for marking automatically an installed fitting. The method may include rotating a fastener to attach the fitting during a fastener tightening operation, measuring a torque applied to the fastener during the fastener tightening operation, and rotating the fastener to a preset angle during the fastener tightening operation. The method may also include marking automatically the installed fitting and the fastener after applying the torque to the fastener and after rotating the fastener to the preset angle.

A further embodiment of the disclosure provides a A self-contained combined wrench and marking system. The self-contained combined wrench and marking system has a wrench. The wrench may include a ratcheting wrench head for rotating a fastener during a fastener tightening operation, and a torque measuring mechanism for measuring a torque applied to the fastener during the fastener tightening operation. The torque measuring mechanism may include a strain-beam that is stressed during the fastener tightening operation, and a stress measuring mechanism for measuring an amount of stress on the strain-beam, wherein the amount of stress is related to torque. The wrench may also include an angle measuring mechanism for rotating the fastener to a preset angle during the fastener tightening operation, and the angle measuring mechanism may include a gyroscope. The self-contained combined wrench and marking system also has a marking system for automatically marking the fastener after the torque measuring mechanism determines that the torque applied to the fastener is equal to a preset torque value and after the angle measuring mechanism determines that the fastener is rotated to the preset angle. The marking system may include a marking fluid reservoir containing a marking fluid, a spray nozzle line connected to the marking fluid reservoir for receiving the marking fluid from the marking fluid reservoir, and a replaceable gas cartridge containing a gas propellant. A first control valve may deliver the gas propellant from the replaceable gas cartridge to the marking fluid reservoir for delivering the marking fluid from the marking fluid reservoir to the spray nozzle line, and a second control valve may deliver the gas propellant from the replaceable gas cartridge to the spray nozzle line for spraying the marking fluid for marking the fastener.

A further embodiment of the disclosure provides a method for installing a fitting and for marking automatically an installed fitting. The method includes a fastener tightening operation. The fastener tightening operation may include rotating a fastener to attach the fitting, measuring a torque applied to the fastener while rotating the fastener to apply a preset torque to the fastener, and measuring a rotation angle of the fastener while rotating the fastener for rotating the fastener to a preset angle to install the fitting. The method also includes a marking operation for marking automatically the installed fitting and the fastener. The marking operation may include delivering a gas propellant from a replaceable gas cartridge to a marking fluid reservoir for delivering a marking fluid from the marking fluid reservoir to a spray nozzle line, and delivering the gas propellant from the replaceable gas cartridge to the spray nozzle line for spraying the marking fluid from the spray nozzle line.

The features, functions, and advantages can be achieved independently in various embodiments or may be combined in yet other embodiments.

DETAILED DESCRIPTION

Referring more particularly to the drawings, embodiments of the disclosure may be described in the context of an aircraft manufacturing and service method100as shown inFIG. 1and an aircraft200as shown inFIG. 2. During pre-production, exemplary method100may include specification and design102of the aircraft200and material procurement104. During production, component and subassembly manufacturing106and system integration108of the aircraft200takes place. Thereafter, the aircraft200may go through certification and delivery110in order to be placed in service112. While in service by a customer, the aircraft200is scheduled for routine maintenance and service114(which may also include modification, reconfiguration, refurbishment, and so on).

As shown inFIG. 2, the aircraft200produced by exemplary method100inFIG. 1may include an airframe202with a plurality of systems204and an interior206. Examples of high-level systems204include one or more of a propulsion system208, an electrical system210, a hydraulic system212, and an environmental system214. Any number of other systems may be included. Although an aerospace example is shown, the principles of the invention may be applied to other industries, such as the automotive industry.

Apparatus and methods embodied herein may be employed during any one or more of the stages of the production and service method100. For example, components or subassemblies corresponding to production process106may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft200is in service. Also, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during the production stages106and108, for example, by substantially expediting assembly of or reducing the cost of an aircraft200. Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof may be utilized while the aircraft200is in service, for example and without limitation, to maintenance and service114.

With reference now toFIG. 3, an illustration of a perspective plan view of a combined wrench and marking system according to an advantageous embodiment of the disclosure is depicted. The combined wrench and marking system, often referred to herein as a marking wrench, is designated by reference number300, and generally includes handle portion302, housing portion304, nosepiece portion306and head portion308.

FIG. 4is an illustration of an exploded perspective plan view of the combined wrench and marking system ofFIG. 3.FIG. 4illustrates various components of marking wrench300, and may be referred to during the following detailed description to facilitate a clear understanding of the marking wrench and its operation.

Returning toFIG. 3, handle portion302includes handle cap310for a user to hold marking wrench300. As will be described hereinafter, handle cap310may be hollow to define a compartment that contains a CO2cylinder to provide pressurized gas for the marking system of the marking wrench.

Housing portion304may include housing body312covered by housing body cover314. A display and control panel316may be mounted on housing body cover314. Display and control panel316, which is also illustrated inFIG. 9and will be described more fully hereinafter, may include display318, On/Set button320, mode button322, and status lights324,326and328.

Housing body312may also include ink refill port332for refilling an ink reservoir included in the marking system of marking wrench300.

Nosepiece portion306includes a nosepiece body534, which is illustrated inFIGS. 4 and 5and will be described more fully hereinafter, that is enclosed in lower and upper nosepiece covers334and336. A spray nozzle338of the marking system may be in the nosepiece body as illustrated inFIG. 3.

Head portion308includes ratcheting head340of the marking wrench. Ratcheting head340is adapted to grip and rotate a nut, such as hydraulic nut350inFIG. 3, in order to fasten hydraulic fitting352to a section354of a hydraulic line. More particularly, marking wrench300may be used to tighten hydraulic nut350to a preset torque value and to then rotate the nut to a preset angle in order to fully tighten the hydraulic fitting352to line section354; and to then mark both the nut and the fitting with ink using the marking system of the marking wrench to indicate that nut350has been fully tightened and that hydraulic fitting352has been attached to line section354in a secure, leak-free manner.

In an advantageous embodiment of the disclosure, marking wrench300may be used to install and mark hydraulic nuts and fittings to assemble hydraulic lines of an aircraft. It should be understood, however, that the marking wrench may also be used in other fastening applications and it is not intended to limit advantageous embodiments to any particular application.

According to an advantageous embodiment, marking wrench300may be about 17 inches long and weigh about two pounds. Marking wrench300may also be less than one inch thick, and thus provides a narrow profile in the plane of rotation of the marking wrench such that the marking wrench may be used in confined areas.

FIG. 5is an illustration of the combined wrench and marking system ofFIGS. 3 and 4with portions removed to show internal features of the combined wrench and marking system according to an advantageous embodiment of the disclosure. More particularly,FIG. 5illustrates marking wrench300with housing body cover314and upper nosepiece body cover336removed. As shown inFIG. 5, marking wrench300may include two circuit boards, main circuit board502in housing body312, and gyroscope circuit board506, also referred to as gyroscope506, in nosepiece body534. By providing a separate gyroscope circuit board, if the gyroscope circuit board506goes bad, it may be replaced independently of main circuit board502. Main circuit board502will be described more fully hereinafter in conjunction withFIG. 6.

Gyroscope506may be used to measure the angle of rotation of a nut being rotated (displaced angle) by marking wrench300, for example, hydraulic nut350inFIG. 3. Gyroscope506actually measures the rate of rotation of the nut, however, this measurement is then integrated using a suitable integration numerical method algorithm, such as Simpson's rule or the trapezoidal rule, in order to determine the angle of rotation of the nut.

Also illustrated inFIG. 5is strain-beam508in nosepiece body534. Strain-beam508may be used to measure torque. In particular, one end of strain-beam508is rigidly attached to nosepiece body534and the other end is free, i.e., the strain-beam is in a cantilever configuration. Strain-pin510is screwed into the free end of strain-beam508and just contacts an inner wall of nosepiece body534. This contact may be adjusted by screwing strain-pin510further into or further out of strain-beam508.

Strain-beam508senses an amount by which it is bent. Specifically, when marking wrench300rotates a nut in a clockwise direction, nosepiece body534bends and pushes against strain-pin510which, in turn, applies a load onto strain-beam508causing it to bend. Through calibration, the amount of stress on the strain-beam as a result of being bent is related to torque, enabling torque to be measured.

More particularly, as a result of the bending of strain-beam508, a voltage sent to the strain-beam changes, due to the strain-beam's change in resistance, then an instrumentation amplifier on main circuit board502amplifies this signal. The amplified voltage signal, or analog signal, is sent to a suitable microcontroller, such as a Microchip PIC microcontroller, on the main circuit board502. The microcontroller has analog-to-digital converter capability so that the analog voltage can be converted to digital format. In digital format, the microcontroller can apply various measured and stored correction factors, such as the calibration factor, to compute torque.

FIG. 5also illustrates vibrating motor512in housing body312, which may be used for tactile feedback. Vibrating motor512may turn on for two seconds after marking wrench300has completed rotation of a nut to indicate to a user that the nut is fully tightened so that the user may get ready for the wrench to mark the tightened nut and associated fitting.

FIG. 6is an illustration of an electronic circuit diagram of the main circuit board illustrated inFIG. 5according to an advantageous embodiment of the disclosure. The electronic circuit is generally designated by reference number600and may include a Microchip microcontroller602, for example, a PIC16F877A microcontroller operating at 16 MHz, for controlling marking wrench300. Microcontroller602may contain 8K, 14-bit words of programmable flash memory and 256 X 8 bytes of EEPROM data memory, and may include30input/output (I/O) ports. As shown inFIG. 6, electronic circuit600may also include LED operation components604for controlling the operation of status lights324,326and328, strain-beam amplifier circuit606for use in measuring torque, pressure sensor circuit608and pressure sensor amplifier circuit610for use in the marking system of the marking wrench, LCD integrated circuit612for display318, membrane switch and debounce circuit614, which is needed to assure that buttons320and322function properly (otherwise pressing a button might turn on then turn off the wrench), buzzer616, resettable fuse618, which is needed in situations when the batteries are inadvertently installed with reverse polarity, and vibrating motor circuit620that includes vibrating motor512.

FIG. 7is an illustration of a fluid circuit diagram representing a fluid system of the marking system of the combined wrench and marking system ofFIGS. 3-5according to an advantageous embodiment of the disclosure. The marking system includes the fluid system, an ink injection system and parts of the marking wrench control system including the pressure sensor608and the pressure sensor amplifier610(not shown inFIG. 7).

The fluid system is generally designated by reference number700. CO2may be delivered by a disposable 16 gram, or other size, CO2cylinder702which contains CO2at approximately 900 psig. As shown inFIG. 4, cylinder702may be supported in hollow handle cap310. Adjustable high pressure regulator704may be preset, by the wrench manufacturer, to output a pressure of about 25 psig from cylinder702. Low pressure line706from regulator704may be split into four lines. One line may be directed to pressure sensor608. Here, the control program, using pressure sensor608and pressure sensor amplifier610monitors the CO2pressure of the lines. When the pressure goes below 22 psig or above 30 psig, the control program may signal the user to change the CO2cylinder702.

The control program checks for over pressure as well as for under pressure because when the pressure in CO2cylinder702drops from use, the low pressure left in the cylinder may cause regulator704to increase the outlet pressure to considerably above 25 psig.

Two lines of the four lines split from line706may supply flow to solenoid-actuated valves710and712. Valve710may be used to operate pilot actuated valve714which, in turn, may inject ink into nozzle line716via ink line718. Solenoid-actuated valve712may be used to flood nozzle line716with CO2so as to propel the ink out spray nozzle338during a marking operation.

The fourth line split from line706may go directly into ink reservoir720which may comprise a low volume pump. A piston, schematically shown at722, may separate the CO2from the ink in reservoir720which is always pressurized. The ink should be pressurized so that it will function properly in all orientations of the marking wrench, especially when spraying in an overhead direction.

The following sequence of events may occur to actuate an ink spray shot:1. Solenoid actuated valve710directs CO2to pilot actuated valve714for a time duration of approximately 10 milliseconds, which is controlled by the control program, to open valve714;2. Solenoid-actuated valve710during the time duration controls the amount of ink injected into nozzle line716;3. Solenoid-actuated valve710is turned off at the end of the time duration;4. Solenoid-actuated valve712directs CO2into nozzle line716to propel ink to spray nozzle338;5. Spray nozzle338aids in atomizing the ink as the ink is sprayed out of the nozzle and onto a nut and fitting.

FIG. 8is an illustration showing an enlarged view of the nosepiece body of the combined wrench and marking system ofFIGS. 3-5. At rest, ink resides in between the inside surface of sleeve802, which is made from a flexible plastic tubing such as polyurethane, and the outside surface of nozzle line716(note that other components illustrated inFIG. 8are shown in phantom lines to better illustrate structural features). Spring804maintains positive pressure on the piston822which in turn puts pressure on sleeve802to maintain a no ink flow condition. When valve710(not shown inFIG. 8) is actuated, CO2is directed into the cylinder820containing piston822, causing the piston to compress spring804, and to move away from the sleeve802, uncovering ink inlet806(a small hole) in nozzle line716. O-ring808maintains a fluid-tight condition between piston822and the cylinder820as the piston moves within the cylinder. The valve on-time controls the amount of ink injected into nozzle line716.

FIG. 9is an illustration showing an enlarged view of the display and control panel of the combined wrench and marking system ofFIGS. 3-5. As indicated with reference toFIG. 3, display and control panel316may include display318, On/Set button320, Mode button322, and status lights324,326and328.

Display318may be an LCD (liquid crystal display), and may display three seven-segment digits without decimal points which may be used to represent letters or numbers. For example,FIG. 9schematically illustrates display318displaying the digits “70” which may represent the letters “TO” for “torque”.

On/Set button320has two functions. The On feature turns marking wrench300on and off. The Set feature may be used to set (store) a value into memory. Mode button322may be used for selecting a desired function among several available functions as will be described hereinafter.

Status lights324,326and328may comprise LEDs (light emitting diodes) of three different colors. For example light324may be green, light326may be yellow, and light328may be red. According to an advantageous embodiment, green LED324may be on during torque measurement, yellow LED326may be on during angle measurement, and red LED328may go on when angle measurement is complete. In addition, red LED328may go on in conjunction with messages being displayed on display318to indicate a fault, such as that the battery needs changing, the CO2cylinder needs replacing or that the gyroscope needs replacing.

FIG. 10is an illustration of a portion of the combined wrench and marking system ofFIGS. 3-5, looking in the direction of arrow10inFIG. 3, to show features of the combined wrench and marking system according to an advantageous embodiment of the disclosure. In particular,FIG. 10shows some features on the underside of marking wrench300.

As shown inFIG. 10, marking wrench300may be provided with electrical power by batteries1002, for example, three AA batteries carried in battery compartment1004in housing body312. The batteries may be easily replaced when necessary by removing four screws1006and removing battery access panel1008.

FIG. 10also shows ink supply viewing window1010. Ink supply viewing window1010enables the current level of the ink in ink reservoir720to be monitored. When refilling of reservoir720is necessary, the refilling may be easily accomplished by injecting ink into the reservoir through ink refill port332(seeFIG. 3) using a syringe or the like. Ink refill port may be closed by a plug402(seeFIG. 4) which may be removed during a refilling operation.

FIG. 10also shows CO2cylinder702which may be easily replaced by fully unscrewing handle cover310.

FIGS. 11A and 11Bare an illustration of a flowchart that schematically shows program logic for installing fluid fittings and fasteners according to an advantageous embodiment of the disclosure. More particularly,FIGS. 11A and 11Billustrate a method for installing fluid fittings and fasteners using a combined wrench and marking system such as marking wrench300inFIGS. 3-5. The method is generally designated by reference number1100, and begins by turning on the marking wrench (Step1102) for example, by operating On/Set button320on display and control panel316. The control program then goes through a diagnostic sub-program (Step1104) during which the program checks battery voltage, CO2pressure, and gyroscope operation. A determination is made whether any action is needed responsive to the diagnostic tests (Step1106). If an action is required (Yes output of Step1106), LCD display318displays appropriate symbols indicating the action that is required, and red LED328also lights up (Step1108). After five seconds, the marking wrench will turn off so that the required action(s) may be taken (Step1110). This will prevent a user from ignoring the display.

During the diagnostic sub-program (Step1104) the gyroscope baseline may also be determined. The gyroscope baseline may be used to determine the nut angle, and should be determined while the marking wrench is not moving.

Returning to Step1106, if an action is not required as a result of the diagnostic tests (No output of Step1106), an options mode may be entered into to select options for operating the marking wrench (Step1112). Entry into the options mode may be accomplished by pressing mode button322on display and control panel316.FIG. 12is an illustration of a Table that describes options that may be selected during the options mode in the flowchart ofFIGS. 11A and 11Baccording to an advantageous embodiment of the disclosure.

As shown inFIG. 12, options that may be selected include ink spray adjustment1202, CO2spray adjustment1204, ink amount1206, change or clear ink1208, measure angle1210, and calibrate1212.FIG. 12describes each of these options. For example, to change the ink amount (Option1206), the Mode button322is pressed to enter into the options mode, then the Mode button is again pressed when IA- is displayed on display318to select the ink amount option1206. Then the On/Set button320is pressed to select and store the amount of ink in each spray. This amount is stored in memory and will not be lost if there is a loss of power to the marking wrench.

A similar procedure is used when the other options shown inFIG. 12are selected. Certain of the options may require entry of a code to enable the user to make modifications, For example, both the angle measuring option1210and the calibrate option1212may require the user to enter a code using On/Set button. The calibration option may also be used to store either or both torque and angle preset values.

Returning toFIGS. 11A and 11B, after completion of operations in the options mode (Step1112), the stored torque and angle values are recalled and displayed (Step1114). This is so the user may verify that the wrench is set properly. Display318may display the torque value followed by the angle value. The marking wrench then starts measuring torque during a nut-tightening operation.

The torque measuring process is generally designated by dashed box1116, and begins by display318displaying current torque (Step1118). Display318may initially display 0 inch-pounds indicating that there is no load on the handle of the marking wrench. Green LED324may also turn on indicating that torque is being measured (Step1120). The user then begins tightening a nut, ratcheting if necessary (Step1122).

As the nut is tightened, a determination is made whether the measured torque is within a selected percentage of the preset torque value, for example, within 5 inch-pounds of the preset value (Step1124). If the measured torque is not within 5 inch-pounds of the preset torque value (No output of Step1124, the method returns to Step1124as the nut continues to be tightened. If the torque gets within 5 inch-pounds of the preset torque value (Yes output of Step1124), buzzer616on main printed circuit board502may beep five times (Step1126) as an indicator.

A determination is then made whether the measured torque is equal to the preset torque value (Step1128). If the measured torque does not equal the preset torque value (No output of Step1128), the method returns to Step1128as the nut continues to be tightened. If the measured torque equals the preset torque value (Yes output of Step1128), the green LED may turn off and the yellow LED326may turn on ending the torque measuring process (Step1130). The method then switches to an angle measuring mode.

The angle measuring process is generally designated by dashed box1132, seeFIG. 11B. Display318may display current angle (Step1134). Initially, display318will show 0 degrees. The user continues to tighten the nut, ratcheting if necessary (Step1136). A determination is made whether the measured angle is within 10 percent of the preset angle value (Step1138) If it is determined that the measured angle is not within 10 percent of the preset angle (No output of Step1138), the method returns to Step1138and the user continues to tighten the nut. If the measured angle is within 10 percent of the preset angle (Yes output of Step1138) buzzer616may beep five times as an indicator (Step1140).

A determination is then made whether the measured angle is equal to the preset angle (Step1142). If it is determined that the measured angle is not equal to the measured angle (No output of Step1142), the method returns to Step1142and the user continues to tighten the nut. If it is determined that the measured angle is equal to the preset angle (Yes output of Step1142), the red LED may go on to indicate that angle measurement is complete (Step1144).

When the preset angle is reached, the wrench may also begin to vibrate (Step1146). This indicates to the user that the wrench is ready to spray. After a time delay of one second, the marking wrench then sprays both the nut and the fitting (Step1148). After the spraying, the marking wrench may automatically turn off (Step1150).

FIG. 13is an illustration that shows an ink mark sprayed on both a nut and a fitting that has been assembled to a hydraulic line section according to an advantageous embodiment of the disclosure. In particular,FIG. 13shows an ink mark1302sprayed on both nut1304and fitting1306that have been attached to hydraulic line section1308to indicate that the nut and fitting have been properly attached to the line section.

Returning toFIGS. 11A and 11B, marking wrench300may include a power off timer that will automatically turn off the wrench after a set time is reached. This timer may be set during torque measuring (Step1160), and may be reset during angle measuring (Step1170). The timer may be set for three minutes although other time periods can also be set if desired. If measured torque or measured angle does not change within the set period of time, the marking wrench automatically turns off (Steps1162and1172, respectively).

FIG. 14is an illustration showing a cross-sectional view of a nosepiece body of a combined wrench and marking system according to a further advantageous embodiment of the disclosure. More particularly,FIG. 14illustrates a marking system in which ink is electronically injected into the ink reservoir rather than by CO2deployed ink injection as in the advantageous embodiment described with reference toFIGS. 3-10.

Nosepiece body1402of the combined wrench and marking system may include a stepper motor1404with gearbox which is controlled by the microcontroller602on the main circuit board of the combined wrench and marking system. The output shaft on the gearbox may be attached to blade coupling1406(shaped similar to a blade screwdriver) which is inserted into a blade receptacle (shaped similar to a slotted screw head) on valve stem1408. Valve stem1408has exterior threads1430which mate with interior threads on nosepiece body1402. Since connected together, by blade coupling1406and blade receptacle, rotation of the output shaft causes the valve stem1408to rotate in nosepiece body1402. As this rotation occurs, the valve stem1408will either extend or retract into the nosepiece body1402, depending on the rotation direction of the output shaft. This will cause the blade coupling1406to be withdrawn or be further inserted into the blade receptacle. The advantage of this coupling arrangement, is that the thrust force is applied on the threads1430and not onto the shaft of the stepper motor1404.

In operation, ink pressurized to about 5 psig is directed into ink port1410. No ink flows, however, until valve stem1408is retracted. When the stepper motor1404is signaled by the control program to rotate a certain number of steps, valve stem1408will rotate in nosepiece body1402causing the valve to retract from the front ink seal1412. Retraction is dependent on the valve stem screw threads1430.

At this point, ink is injected into mixing chamber1414. The valve stem is then extended forward to seal front ink seal1412. Then an electronic valve (not shown inFIG. 14, but which functions similarly to valve712) is signaled to inject CO2via CO2flow line1418at about 25 psig into mixing chamber1414. The mixing chamber1414, is contained within nozzle sleeve1420. Ink and CO2mix together in chamber1414, and the atomized ink is propelled down nozzle sleeve1420and out nozzle hole1422.

FIG. 15is an illustration of an enlarged view of the mixing area shown inFIG. 14.FIG. 15illustrates features to eliminate ink clogging. Specifically, the front portion of valve stem1408is designed to retain O-ring1412and break up any dried ink when the valve stem1408is retracted. This is facilitated through the close tolerance hole in the nosepiece and the O-ring retainer design, generally shown at1510.

A combined wrench and marking system according to advantageous embodiments is completely self-contained and does not require connection to an external air line or to any other external source. As a result it is easy to handle and manipulate. Use of a combined wrench and marking system according to advantageous embodiments may reduce the number of hydraulic leaks that occur during leak-testing of a fitting that has been attached to a hydraulic line section because both the nut and the fitting are automatically marked only after the nut has been properly tightened. This will help ensure that joints that have not been properly assembled will not be inadvertently marked.

The combined wrench and marking systems according to advantageous embodiments is light in weight and compact in size. In addition, the combined wrench and marking systems according to advantageous embodiments is less than one inch thick and has no protruding components, and thus provides a narrow profile in the plane of rotation of the marking wrench such that the marking wrench may be used in confined areas.