The present invention relates to turbomachines and particularly relates to a tool for repairing or upgrading components in a compressor.
In axial flow compressors, stator vanes alternate with rotating blades or buckets in the various stages of the compressor. The stator vanes are circumferentially spaced one from the other about the compressor axis and are secured to the upper and lower compressor casing halves. The upper and lower casing halves are joined one to the other at the compressor midline and provide a complete circumferential array of stator vanes for each compressor stage. As each rotating blade mounted on the rotor completes each revolution at a given rotational velocity, the rotating blade receives aerodynamic excitation pulses from each stator vane. This pulse can be generated from the wake of the upstream stator vane or the bow wave of the downstream stator vane. It is also possible to generate excitations in the rotating blade from differences between the upstream and downstream stator vane counts. These pulses induce a vibratory response in the rotating blade that can be deleterious to the rotating blade causing failure due to high cycle fatigue.
Typically the stator vane or blade count in the upper and lower halves of the compressor casing for a given stage are equal in number to one another. For example, in an initial stage S0 of a given compressor, the blade count for the stator vanes in each of the upper and lower compressor casing halves may be 24/24. In the next stage S1, the blade count may be 22/22. The first number represents the number of stator vanes in the upper casing half and the second number represents the number of stator vanes in the lower casing half of the same stage. The total stator vane count in S0 and S1 is therefore forty-eight and forty-four stator vanes respectively. However, because of the vibratory responses of the rotating blades, non-uniform vane spacings between upper and lower casing halves have been used in the past. Thus, different and alternative upper and lower blade counts in succeeding stages have been provided to reduce or eliminate the vibratory response. For example, in one compressor, stages S0 and S1 have had vane counts of 24/23 and 23/24, respectively. These non-uniform blade counts have been used in original equipment manufacture.
There are, however, a significant number of compressors in use in the field where there is an equal number of stator vanes in the upper and lower compressor halves for given stages. Certain other compressors in the field have an unequal number of stator vanes in the upper and lower compressor halves with adjacent stages, e.g. S0 and S1, having equal numbers of blades but alternate blade counts between the upper and lower halves of the compressor casing. Changing blade counts in the field was not previously considered practical since costly removal of the rotor in the field was required.
Because the rotor is closely fitted to the middle and aft (or rearward) sections of the compressor, it is geometrically difficult to reach the areas where the blades reside or to drill, tap, and counter-bore load dam pin holes in the area desired. Additionally, the current known methods for removal of these blades increase the likelihood that the rotor, stator blades or adjacent hardware may be damaged during the removal process. Moreover, the extended reach and limited access to the stator blades being removed underneath the rotor and rotor blades creates an ergonomic issue potentially leading to operator injury.
In accordance with an aspect, a tool for drilling, tapping, and back spot facing at least one hole in a turbomachine includes a servo motor cutting device configured for use with a cutting tool. A drill unit skid is adapted to engage a hook fit slot in a case of the turbomachine and for supporting the servo motor cutting device. The drill unit skid includes hook fit slides, and the hook fit slides are configured to guide the drill unit skid along the hook fit slot and act as a stop in a radial direction with respect to the turbomachine. A laser positioning device is configured to detect the position of the cutting tool. A micro switch is configured to stop the servo motor cutting device when the micro switch activates. The servo motor cutting device rotates the cutting tool to create the at least one hole, and wherein a rotor of the turbomachine is left in place during drilling, tapping and back spot facing.
In accordance with another aspect a tool for drilling, tapping, and back spot facing at least one hole in a turbomachine is provided. The tool includes a servo motor cutting device configured for use with a cutting tool. A drill unit skid is adapted to engage a hook fit slot in a case of the turbomachine and for supporting the servo motor cutting device. The drill unit skid includes hook fit slides, and the hook fit slides guide the drill unit skid along the hook fit slot and act as a stop in a radial direction and an axial direction. A laser positioning device is configured to detect the position of the cutting tool. The servo motor cutting device rotates the cutting tool to create the at least one hole, while a rotor of the dynamoelectric machine is left in place during drilling, tapping and back spot facing.
In accordance with yet another aspect, a tool for drilling, tapping, and back spot facing at least one hole in a turbomachine is provided. The tool has a servo motor cutting device configured for use with a cutting tool. A drill unit skid is adapted to engage a hook fit slot in a case of the turbomachine and for supporting the servo motor cutting device. The drill unit skid includes hook fit slides, and the hook fit slides are configured to guide the drill unit skid along the hook fit slot and act as a stop in a radial direction. The hook fit slides act as stops in two opposing radial directions with respect to the turbomachine. A micro switch is configured to stop the servo motor cutting device when the micro switch activates. The servo motor cutting device rotates the cutting tool to create the at least one hole, while a rotor of the turbomachine is left in place during drilling, tapping and back spot facing.
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Compressors and their associated components may need to be repaired or upgraded during their service life. In some applications it may be desired to replace stator vanes with vanes having a new shape or profile and/or grouping configuration. Some known processes currently require the removal of the rotor, which significantly increases outage duration and cost. An apparatus, according to aspects of the present invention, utilizes an iterative process for removing single stator blades with the rotor in place. This in-situ process greatly facilitates upgrading or repairing the compressor as the previous known method required removing the rotor.
After the removal of the stator vanes in the axial compressor portion of a gas turbine, load dam pins may be installed as an upgrade option. According to aspects of the present invention, the holes for the load dam pins may be drilled, tapped, back spot faced and counter-bored with the rotor in place or “in-situ’ to allow for the installation of the load dam pins. The purpose of the pins is to equally distribute the aerodynamic load circumferentially at strategic locations for the stator vanes. The tool may be used with any dynamoelectric machine, including, but not limited to compressors, gas turbines or steam turbines.
The drill unit 500 may be comprised of an electric servo motor 510 attached through an adaptor plate to a right angle gearbox 520. This unit provides the power to perform all cutting operations during the load drilling process. All cutting operations, drilling, back spot facing, counter boring and tapping are achieved through the use of cutting tooling connected to this drill unit. The unit may also be equipped with two hydraulic double acting cylinders that provide the forces necessary to apply pressure to the drill, spot face cutter and tap for advancing and retracting the tooling through the casing material.
In addition to the advance and retracting double acting cylinders the unit may have two hydraulic cylinders that provide the clamping force required to hold the unit radially during the drilling operations. This clamping is accomplished by actuating the cylinders to apply a radial inward force on the drill unit to hold it against the hook fit 833 during the drilling, spot facing and tapping operations. The unit may include another hydraulic cylinder that is attached to a locating or shot pin which when actuated provides the circumferential location of the drill unit by locating in the drill unit mount or in a previously drilled hole.
The drill unit skid 600 serves as the mounting fixture for all devices for the drill unit. Some of the notable features are the hook fit slides or feet 640 and clamping actuators. The feet 640 serve two main functions, they guide the skid 600 along the hook fit 833 and position the drill 500 in the axial direction 101 and when the clamping actuators are energized they act as a stop in the radial direction 103 to push against. The feet 640 are sized so that there is enough clearance for the sliding motion needed but not enough to allow the unit to escape the hook fit 833 in the radial or axial directions. The skid 600 may also be equipped with two attachment points for pinning the operator control/push rods 810 and the vacuum system. Loops may be located on each end of the unit to attach the control/push rods that are used by the operators to push and pull the unit along the hook fit during all operations. On the forward end the loop may be used to attach a vacuum attachment to remove cutting debris and chips generated during the various processes.
The pinning process can be accomplished by mating the rods and vacuum attachment on either end and inserting a ball pin through all pieces and thus attaching the rods and vacuum attachment to the skid. The skid also serves as an attachment point for a protective hose which houses the hydraulic lines that power the unit. This can prevent inadvertent disconnection of the hydraulic hoses from the unit and protects the hydraulic lines from nicks and scuffs during the operation of the unit.
The drilling, tapping, and back spot facing method or process, according to aspects of the present invention, begins with a step of installing a mounting fixture 840 on the side horizontal joint of the lower casing half 32 utilizing an alignment block between the fixture and the hook fit slot 833 of the lower casing half 32. This aligns the drill unit skid 600 and the hook fit 833 to facilitate the feeding of the drill unit skid 600 into the “T” slot or hook fit 833 of the compressor case 32. Additionally, the mounting fixture sets the positioning of all holes (e.g., eight) that will be drilling into each half of the case during the process. The fixture does this by utilizing a hole that is located in the base of the fixture. This hole is used to define the location of the first hole to be drilled. Each subsequent hole will be based off of this first hole location. The tool 1000 may now be inserted into the mounting fixture 840 and subsequently into the hook fit slot 833. This is achieved by actuating a shot pin, on the drill unit skid 600, into the hole in the mounting fixture. The shot pin locates the position of the drill unit (or tool 1000) circumferentially to the hole being worked and the clamping cylinders provide an upward force to hold the tool 1000 in position in the hook fit during all operations (drilling the holes, back spot facing and tapping) during the process. The actuation of the shot pin locate the tool 1000 circumferentially with respect to the lower casing half 32.
Prior to mounting the tool 1000 on the fixture a bit is installed into the drill 500. This bit is custom due to the length and machining necessary to lock into the bit chuck. Once installed, the unit is stroked for forward and reverse movement and rotation. Once proven, it is positioned on the mounting fixture. The fixture is equipped with a lock to suspend the drill 500 prior to feeding it into the machine. This lock is utilized for a couple of reasons. The drill 500 may be heavy and by suspending it in this position it makes tool change over easier for the operator.
The operator unlocks and slides the tool 1000 into the hook fit and actuates the shot pin to locate the unit for the first hole position. The shot pin locates the tool 1000 by utilizing the hole located in the base of the drill mount. Once in the locating hole the operator actuates the hydraulic clamps to hold the tool 1000 against the bottom side of the hook fit. The clamp is configured to secure the tool 1000 to the hook fit slot 833. This helps to ensure the tool 1000 does not slide or move during the drilling, spot facing and tapping operations. Once the tool 1000 is locked into position the operator can choose the function from the pendant that they want to perform. The operator can choose, drill, spot face or tap, advance and retract depending on what operation is needed. The first operation is drilling one of the holes. The operator drills the first hole and then uses this hole to locate the position of the next. This drilling operation is repeated until all eight holes have been drilled. Obviously, any number of holes may be drilled and more or less than eight holes could be chosen, based on the specific application.
Once all holes have been drilled the drill unit 500 can be removed and the operator may select the spot face operation on the pendant. The split arbor is installed for the back spot facing operation. The arbor is split due to the limited amount of stroke range of the drilling unit. The first half of the split arbor is locked into the drill and the unit is fed into the hook fit 833 the same way as during the drilling operation. Once the tool 1000 is at the first hole location and locked into place the drill 500 is stroked or advanced to the full stroke so that the second half of the arbor can be attached. This is achieved by feeding the second half of the arbor through the hole that was previously drilled. Once in place the arbor is tightened using a cap screw. Next, the back spot face cutter is attached to the arbor. This arbor cutter arrangement is designed so that when the cutter is rotating (cutting) the rotational direction keeps it locked into position. A spot facing of the hole is now performed. The drill 500 is retracted to the “fully” retracted position. This is what sets the depth of the spot face drilling operation. When the unit is fully retracted the spot face is set to the correct depth. This is an important depth since this surface sets the location of the load pin and the load pin to stator blade relationship. The drill 500 is then advanced full stroke and the spot face cutter and arbor are removed. The tool 1000 is then unclamped and moved to the next hole location. This process can be repeated until all holes have been spot faced. Once all holes are spot faced the tool 1000 may be removed from the machine for a tooling change.
The next operation is the tapping of the holes. The operator selects the tapping operation on the pendant. The custom tap is loaded and locked into the drilling unit while the drill 500 is suspended on the mounting fixture 840. The tap is designed to fit into the chuck and it pushes the tapping chips forward unlike a conventional tap. The drill 500 is then fed into the machine and is advanced to the last (e.g., eighth) hole location to start the tapping process. The tapping operation is started at the last hole due to the shot pin requiring an untapped or smooth hole to locate from during the process. The tapping operation starts with the last hole and works backwards towards the first hole. Once the last hole is tapped the tool 1000 is pulled back to tap the next (e.g., seventh) hole. This is repeated until all holes have been tapped. The tool 1000 is then disassembled and mounted on the upper half casing where all operations can be repeated. In addition, the method may include the step monitoring a depth of a cutting operation with a laser positioning device 1010 and controlling operation of the tool 1000 based on the depth. The method may also include the step of monitoring a depth of a cutting operation with a micro switch 1120 and controlling operation of the tool 1000 based on activation of the micro switch 1120.
It will be appreciated that the removal of the upper casing half of the compressor to add, repair, upgrade or perform the above described drilling, tapping, and back spot facing method on the compressor does not require the removal of the rotor 12 from the lower casing half 32. This enables the compressor to be modified by the above described drilling, tapping, and back spot facing method in the field or in situ.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
The present application is a continuation-in-part of application Ser. No. 13/967,590 filed on Aug. 15, 2013, which is hereby incorporated by reference.
Number | Date | Country | |
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Parent | 13967590 | Aug 2013 | US |
Child | 15257260 | US |