Analysis enabling stress relaxation of a material under test

Abstract

The analysis of residual stresses in materials is dynamic and accurate systems and methods for performing these analyses in non-laboratory environments can be difficult and inaccurate. A method of using a portable, field-deployable device with high accuracy is disclosed, wherein accurate and repeatable residual stress analysis can be performed in a non-laboratory environment to significantly improve diagnostics, maintenance, and life expectancy.SOLUTION: Machining a feature on the component under test at a predetermined angle by applying a Cut 190 to the face of the component under test, locating a point determined by the placement of a strain gauge 195, and removing material in the vicinity thereof to alter existing residual stresses at that point, wherein the machining comprises a plurality of light cuts without introducing additional stresses, such that the residual stresses in the region proximate the feature are isolated from those in the bulk; SELECTED DRAWING: Figure 1F

Description

[Background technology]

[0001] When metal is formed in some way or manner as a result of manufacturing, residual stresses are created within the material. These residual stresses affect material performance and can be difficult to quantify. Find out the methods used to reduce the magnitude of residual stresses, e.g., heat treatment. Generally, after the process or treatment is completed, Some residual stresses are present. In some manufacturing processes, residual stresses are intentionally created. For example, shot peening using steel shot or laser peening may be used. Mechanical surface treatments used to improve fatigue performance, such as rubbing, can leave residue on the surface of the material. Nitriding in a nitrogen-rich atmosphere creates residual stresses. Surface treatments are common processes such as chemical treatments, case hardening, and heating. Although it only affects a thin layer of the material, this reduces or prevents the formation of cracks that can initiate failure. cracks are usually caused by extreme stress or by the This is an area that propagates over time and ultimately leads to catastrophic failure of the component. Flow.

[0002] Practical characterization of residual stresses in materials is difficult and is therefore not routinely performed in engineering solutions. Solution is a process whereby a failure mode or life is reliably achieved on a statistically significant basis. One consequence of this is that processes are often stochastic in nature. This means that safety factors supported by low-quality data are It is clear that incorporating numbers is costly and full of uncertainty, and Using only what is believed to be a representative sample of data is a risk factor for questionable data. This is an example of the uncertainty that leads to These processes have been improved to allow accurate residual stress measurements to be made on the parts. It is clear that there is an urgent need for systems and methods for Economically, there is a need to significantly improve the accuracy of the machining equipment typically used for analytical work. There are advantages to being able to perform analysis on-site, rather than transporting parts to a remote facility. This avoids the cost and delays that would otherwise occur if the software needed to be revoked. This is a critical component of high-value systems. This is especially true when components are being considered, e.g., turbine blade failure. The consequences of this can be catastrophic, but current processes make it difficult to detect the onset of the failure. Delays that occur when component parts must be transported to a remote facility for processing The opportunity to introduce the analysis process to the part is quickly approaching, as the development speed slows down due to the extension of the An added benefit is that the parts never have to leave the facility where they are stored. The main advantage is that it simplifies the task of tracking parts. In some cases, for example, drilling is required. Moving large parts, such as large pipes that may become critical, is simply impractical. Being able to bring the analysis into the part is a much better solution. Summary of the Invention

[0003] The present invention uses a machining process to allow stress relaxation of the material during testing. The present invention relates to systems and methods for analyzing material properties of components and structures.

[0004] A fixed laboratory for analyzing the residual stress state of components provides excellent measurement results. While these can produce positive results, they are typically expensive to implement and are not widely available to a wide range of customers. Supporting these clients requires permanent housing and costly processing and documentation processes. be.

[0005] The measurement of surface residual stresses on material samples is performed by locally mechanically removing material and then measuring the residual stress. It can be done by measuring a parameter related to the force, usually a change in strain or deformation. The strain is measured as a function of the material removed. This is typically done using a strain gauge array. The part is then fitted with a microscope in the area of ​​interest, a small hole is drilled in the part, and the microscope is then fitted with a microscope with a small number of microscopes positioned radially adjacent to the hole. The effect of this residual stress relief can be measured by measuring the change in strain using strain gauges. This usually involves applying three or more strain gauges to the material and determining the exact position of their placement. and angle data are recorded and the resulting residual strain is calculated relative to a given axis of the material. The stress must be mathematically derived. With current technology, these three strain gauges are They can be assembled onto a single substrate and mounted as a single part, and the array typically includes: Two gauges are positioned perpendicular to each other and a third gauge is positioned at a 45° angle to the other two. As is common practice, each gauge element incorporates a centerline marking. This makes alignment easy and allows for alignment in any direction on a plane using familiar mathematics. Residual stress in the direction can be calculated.

[0006] One well-known and widely used technique for measuring near-surface residual stresses is It is necessary to drill a small hole precisely in the center of the strain gauge array, which allows for local residual stresses. The force is relaxed and the resulting strain measured is related to the change in residual stress. The term refers to the intersection of the marked axes of the gauge array elements, in this case the strain gauges. A circle is sometimes called a rosette. The elements are arranged radially around the center of the circle. The holes are generally placed halfway up the diameter of the circle, or radially in one quadrant of the circle. Alternatively, the material may be fabricated to have a depth equal to a predetermined distance along a representative surface of the material. A slit of a depth of 100 mm is cut, the change in strain due to the slit is measured, and the measured strain is calculated. Residual stress is calculated from the

[0007] Typically, component parts are drilled or slit after being received in the laboratory. It is divided or cut so that the element of interest can be accurately placed into the machine used for cutting. The more handling a part undergoes, the greater the chance of changing the residual stresses in the part being tested. Additionally, cutting and clamping the sample fixtures can add stress to the parts. Before machining, the element to be analyzed must be strain gauged. , which is usually done to ensure that the adhesive used to secure the gauge or gauge array is effective. This means that the area where the gauge is used needs to be cleaned. A wire is connected to the strain gauge element so that it can be measured and recorded. , as part of a Wheatstone bridge array, which is well known in measurement technology.

[0008] Once the initial reference point has been established, the part may be aligned in preparation for cutting. Once machining is complete, remove the part from the machine and take a new strain gauge reading. In some cases, this measurement may be performed in situ. The difference between the initial value and the previously established reference value is due to the machining process. It corresponds to the residual stress value before the residual stress is released.

[0009] To obtain very high quality results, dedicated equipment is required that is not entirely dependent on a laboratory environment It is also clear that the accuracy of existing instruments needs to be improved. The objective of the present invention is to improve accuracy beyond that currently available, Larger specimens need to be cut so they can be mounted on a machine for cutting force relief features. Reduce the complexity and improve the quality of residual stress measurements through the development of a single, integrated, dedicated instrument. slitting or slotting, drilling, annulus or more complex Performing features, such as ring core cuts, slot intersections (plus signs), etc. The solution is to develop dedicated equipment or to simplify or speed up the measurement procedure. Advances in computer technology and advanced materials are being used to create specialized devices that can move around elephant parts. Dedicated devices are portable and can be attached directly to the test specimen. It can be used as a bench machine in a temporary location or as a stand-alone machine.

[0010] The various features of the present invention described above can be implemented singly or in combination. These and other features of the present invention will be further described in the following detailed description of the invention. This is explained in more detail in conjunction with the following figures.

[0011] In order that the invention may be more clearly ascertained, some embodiments will now be described, by way of example only. Reference will now be made to the accompanying drawings, in which: [Brief explanation of the drawings]

[0012] [Figure 1A] FIG. 1 shows a plan view of a single strain gauge with alignment marks. [Figure 1B] 1 shows a single-quadrant rosette version of the strain gauge. [Figure 1C] 1 shows a typical simplified Wheatstone bridge. [Figure 1D] 1 shows a strain gage mounted on a test specimen where the annulus has been machined to separate the gage area from the bulk material. [Figure 1E] FIG. 1D shows a side view of the annulus of FIG. [Figure 1F] A strain gauge is attached to the specimen and linear slots are machined to relieve residual stresses. [Figure 1G] Shown is a cutting profile with a linear staircase appearance to facilitate chip removal. [Figure 1H] Also shown is a cutting profile with a non-linear staircase appearance. [Figure 2A] 1 illustrates one embodiment of a machine according to the present invention for identifying a region of interest; [Figure 2B] 1 shows a simplified diagram of a typical probe assembly having a single axis of adjustment. [Figure 3] Shows one of the moving parts of a machine and its drive mechanism. [Figure 4A] 1 shows schematic details of a cutting motor, including mounting and cooling equipment, and a camera system. [Figure 4B] 1 shows a simple air supply including a pump and filter to cool the air. [Figure 5A] 1 shows the camera, its shroud, reticle and illumination device. [Figure 5B] 1 shows the camera, its shroud, reticle and illumination device. [Figure 6]1 shows an alternative vision system based on fiber optic technology, with an illumination system positioned in close proximity to the cutting tool. [Figure 7] FIG. 1 is a block diagram of a dedicated device showing the interconnection of machine parts. [Figure 8] A typical protective enclosure for a machine is shown. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will now be described in detail with reference to some embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific examples are used to provide a thorough understanding of embodiments of the present invention. However, those skilled in the art will recognize some or all of these specific details. It will be apparent that embodiments may be practiced without all of the above. Well-known process steps and / or structures have not been described in detail to avoid unnecessary obscuration. The features and advantages of the embodiments are better understood with reference to the following drawings and discussion. It can be easily understood.

[0014] Aspects, features, and advantages of exemplary embodiments of the present invention are described in the following detailed description in conjunction with the accompanying drawings. The described embodiments of the present invention provided herein will be better understood with reference to the description. It is understood that the embodiments are presented for illustrative purposes only and are not limiting. It will be apparent to those skilled in the art that all features disclosed in this description may be used in conjunction with the present invention unless specifically stated otherwise. Unless otherwise specified, alternative features serving the same or similar purpose may be substituted. Thus, numerous other embodiments of such modifications are within the scope and spirit of the invention as defined herein. Therefore, the embodiments disclosed herein are not intended to be limiting unless expressly stated. As examples of absolute and / or continuous terms, e.g., "always" ), "will", "will not", "will "shall," "shall not," "mu "st", "must not", "first", "i initially," "next," "subsequently" ", "before", "after", "lastly" The use of terms such as "and" and "finally" is not intended to limit the scope of the invention. Conversely, terms like "can" or "may" are used interchangeably and in the disclosed embodiments as alternatives and / or options. It is intended to describe all features, i.e., when they are not necessary or desirable. There is.

[0015] Automated residual stress analysis of material samples in the laboratory or on-site without the need to transfer the material to another facility A method and apparatus for facilitating the measurements is described.

[0016] You may choose one or more locations to make measurements. If strain gauges are used, Clean the gauge or strain gauge array and insert one or more measuring tubes appropriate for the intended measurement. Once installed in place, one or more strain gauges or arrays can be mounted in a position that allows the starting strain to be recorded. The newly applied strain gauge can be connected to a measuring device that displaces the resistance from its starting value. Since there is no measurement error, this is effectively the zero point from which subsequent measurements can be referenced. In the example, strain gauges are coupled to analog-to-digital converters to convert the measurement data into machine-readable format. file and can be used after the completion of one or more machining processes to determine the associated strains. The residual stress state of the material can be determined by one or more machining steps. can be calculated for each of these, and the results are presented in numerical or graphical form. Other methods using optical techniques may also be used to make strain measurements.

[0017] In some embodiments, small slots can be cut into the surface of the material. The slot has a predetermined shape and is cut perpendicular to the surface at the point of the feature. If a single gauge is used, the plane of the slot should be such that the strain gauge sensitivity is Preferably aligned perpendicular to the high direction, but if a rosette array is used In areas with high curvature, the correction rule that the inspector specifies for the analysis According to the rule, the machined features may be slightly angularly offset.

[0018] In a simple embodiment, the device may be used to measure a specific field on a strain gauge or on a test material. The linear slide is attached to a base plate that can be precisely positioned relative to the The slide can be moved with high precision along the slide direction relative to the base plate. This positioning may preferably be achieved using a linear actuator, but will be readily apparent to those skilled in the art. Other known methods may also be used.

[0019] The machining tool is mounted on a slide and preferably moves parallel to the work surface The vertical position of the slide can be adjusted. a cutting tool coupled to the motor spindle, the tool being adapted to adequately cut the sample material; The motor may be mounted on a vertical slide, and its position The cutting tool is controlled by a linear actuator, allowing for automatic, step-by-step cutting. Therefore, the cutting width can be adjusted by advancing the slide on which the motor is mounted. Therefore, it can be set by selecting the diameter and cutting depth of the cutting tool. The slide attached to the plate is moved, thus achieving a predetermined and variable width. A linear slot of a suitable depth and length is cut into the material and located adjacent to the gauge or gauge array. The residual stresses that form in the material are isolated from the residual stresses in the bulk material. Other methods such as EDM may also be used, and EDM techniques allow for the erosion of very fine features. Food becomes possible.

[0020] Add a second slide that moves in the same plane as the base plate and replaces the first slide. By connecting a motor slide to this, the cutting tool can be moved in three dimensions. If the actuation step is small enough, a slot with a complex profile ( In one embodiment, a strain gauge is attached and a circular Or an annular slot is cut and the strain gauge is now mounted on the resulting island. The array is attached and separated from the bulk material. When cutting glass, circular chipping occurs due to inadequate removal of material chips. Tool chatter at the bottom of the cutter is significantly reduced, and chip residue is reduced when using high-speed milling cutters. The slot or slit (long slot, groove) intersection can effectively remove residue. Other features, such as grooves or more complex shapes, may be cut into the material. The cut shape is formed from a pair of symmetrical intersecting cuts, resembling a "plus" sign. This results in features of a desired shape.

[0021] Optical components may be used to facilitate accurate positioning. In this example, the camera is positioned so that its viewing axis is in the plane of the cutting spindle and approximately parallel to the spindle. In this way, the optical graticule attached to the camera The distance offset between the defined point and the center of the cutting tool is determined, and this offset comparison A positive coefficient is applied to the control electronics so that once a point is located, the tool will be at the same point. You can move it around and use it as a reference to perform your cuts. Use simple trigonometry to make this determination. Misalignment errors can be corrected using test coupons for the cutting tool. Strain gages can be detected by the operator or automatically using automated feature detection. The image can be aligned to a feature on the image or specimen.

[0022] In a second embodiment, a fiber optic cable is used to allow the camera element to be remotely located. Modern camera components are very small and The lens is protected or covered from metal debris generated by the cutting action of the tool. If the camera is suitable, the modem camera component may be placed near the cutting axis. A camera may be attached to monitor the cutting live as it is being cut.

[0023] The third example allows the machine to create the exact profile of the part being machined. Machining of features can be complex as it incorporates a profiling tool that For reference, the x and y axes are the base plates of the machine. The Cartesian (x, y) axis is defined as lying in the plane of the The use of circular (r, q, f) coordinates is for ease of explanation only; circular (r, q, f) coordinates are also used. It is clear that the profiling tool can be a conventional machine tool or a specialized tool. This latter feature may be implemented using the autofocus function of a camera attached to the device. The function allows you to select either a specific feature or an adjacent surface profile. The cutting depth can be controlled very precisely, e.g., for test samples with curved surfaces, The bottom of the section can be positioned precisely below the surface. The material on the side opposite the strain gauge is positioned so that it approaches a gently sloping transition. The slot is cut by removing the groove in a stepped manner. In a similar manner, both ends of the slot are tapered. In both cases, the transition can be linear or directed against the slope. It may have mathematical properties.

[0024] First, refer to FIG. 1A, which shows a typical strain gauge 100. In this example, the strain gauge The sensor is arranged vertically along the axis along which the displacement is measured. Electrical connections are made and the resistance of the track between them is measured. When a longitudinal movement is applied, the conductor 107 joining these pads stretches, increasing its resistance. Similarly, a strain that shortens a conductor by compressing it will result in a decrease in resistance. These changes are small and barely perceptible to the naked eye, but can be measured electronically. This change in resistance can be related to the stretching or contraction of the material under test using a calibration curve. may be calibrated using a known force applied to

[0025] FIG. 1B shows an array of three aligned strain gauges 120, 130, and 140. The extension axes are 0 degree, 90 degree, and 45 degree lines, respectively. , 140, 130. This type of array can be used to create three independent By precisely placing the gauges, strain in any direction can be mathematically solved. The material has the property that as it stretches, its resistance increases as it gets thinner. The opposite is also true: when the gauge element is compressed, the resistance decreases. Therefore, when stress is applied to a material, a corresponding displacement (strain) occurs, and this displacement is called a strain gain. In typical applications, these changes are measured as changes in the resistance of the Note that this is a very small change in the It is important to do so.

[0026] Traditionally, Wheatstone bridges are designed to mitigate the imbalance that occurs when the resistance of the bridge elements changes. The balance is used to determine the resistance of the strain gauge. Such a bridge is shown with a single variable element 170. Two nominally equal resistor dividers A voltage of 150Ω is applied to each of the devices. The polarity of the applied voltage should not affect operation. However, ideally, excessive current should not flow, as current flow generates heat. This increases the temperature of the element, causing the resistance of the element to change, which reduces the accuracy of the technique. Therefore, it is important to minimize the temperature variation between the elements that form the bridge. This involves some effort to keep the temperature constant between the elements and to reduce the drive voltage to prevent excessive drift. This is best achieved by keeping the resistor to a value that provides sufficient sensitivity without any distortion. The ratio of R1155 to R3160 is the strain gauge R of resistor R2165 G 170 resistance At the junction of R1155 and R3160, The voltage at R2165 and R G Since the voltage at the junction of 170 is equal to The measured voltage Vmeas180 will be zero, but in reality, it may vary depending on manufacturing tolerances and the strain gauge connection. A variable or adjustable fixed resistor is provided to account for discrepancies due to the resistance of the wire used in the It is common to have a resistor between the gauge and the bridge. Since the impedance is broken, a non-zero voltage will be present at 180. The ridges can also be made very sensitive to changes in gauge resistance due to changes in strain. Very good resolution can be achieved, which has been the standard since the early days of electrical engineering. This was a useful measurement method.

[0027] In this embodiment, one or more strain gauges are attached to the component of interest. Strain gauges are typically secured to the test site with a high quality adhesive. of material is applied to the cleaning area, but the strain gage manufacturer will advise which adhesive is preferred. Although guidance is provided on the use of fast-drying cyanoacrylates, completely adequate results are usually achieved with This is achieved using a glue adhesive.

[0028] Referring to FIG. 1D, an annular slot 187 is machined adjacent to the gauge slot 187. 85 is shown. For clarity, the illustration shows a representative single gauge. This may be a gauge array that allows for the resolution of strain in any direction. This releases residual stresses accumulated on the surface of the material, which is then released from the bulk material 184. This is because the area is qualitatively separated and a small island 183 is formed on which the gauge is attached. Now it is free. Figure 1E shows the structure of Figure 1D in cross section, Transverse dimensions are exaggerated for clarity and do not represent actual sample dimensions. FIG. 1F shows that when a linear slot 190 is cut, the stress in the area being measured is compared to the bulk stress. 195 or gauge array. The experiment records the change in strain when the residual stress near the slot is isolated from the bulk material. Previously, residual stress was relieved by simply drilling holes at the intersections of the three axes of the strain gauge array. Although this machine can perform this operation, it is well within the skill of the art. It is documented and therefore not shown.

[0029] 1G and 1H show that the transition is steep only at the edge of the cut closest to strain gauge 187. The opposite side of the cutout has a gradual transition, giving the appearance of a staircase with two or more steps. The 188 or 189 are easy to machine and provide a smooth transition if the step size is properly selected. The step size may be equal 188 intervals or Other methods, such as the simplified exponential relationship 189 shown in Figure 1H, may be used. In a similar manner, although not shown, the ends of the slots may also be cut in this manner. The big advantage is that chip removal becomes easier and the cutting The tendency of the tool to stick or break in the cut is greatly reduced. The step cutting depth increases as the transition is approached, showing a convex shape. It is clear that it would be equally practical to reduce the cutting depth and provide a concave shape. Either method of producing an exponentially gradual transition is acceptable.

[0030] In one embodiment, the strain measurement is performed using a distinct light source, such as a laser or an array of lasers, and a Another embodiment is to use an optical system with one or more detectors. A system of correlations may be used to determine the change in strain or displacement, or Electronic speckle pattern interferometry may also be used. Other strain or displacement measurement methods The temperature of the sample during the test may be measured using the characteristics of a thermistor or thermocouple. It may be optically detected and incorporated as a function of a camera attached to a dedicated device. It may be included.

[0031] FIG. 2A shows one embodiment of a machining tool according to the present invention. It is typically assembled to a base plate 205 with three legs 210 to ensure stability in most configurations. In one embodiment, all three mounting legs 210 may be adjustable, As a result, the base plate is Although this is not strictly necessary, in another embodiment the machine may or may not align the surface of the part. It can track accurately, which is useful for simple tasks with few complex curves. If the surface of the part to be machined can be mapped, two of the legs 210 One or more actuators are used to parallelize the machine to the desired machining area. may be used to automatically adjust.

[0032] The X-axis drive motor is shown at 215. This is a linear actuator and This may take any of the following forms. Typically, this involves rotating a ball screw or lead screw. The stepper motor or servo motor drives the actuator, which then drives the plate that holds the moving part of the machine. The drive motor 215 drives the platform along the x-direction. The motor 215 is selected for its ability to generate high torque. If the motor is a motor, the electronic control unit will provide appropriately phased power to drive the motor at a given speed. The speed and direction of the moving platform can be controlled to position the platform as needed. High precision actuation mechanisms used in either x, y, or z motion It is preferable to enclose such mechanisms to protect them. To enable this, sliding panels or bellows such as those shown in 218 are used for this purpose. It turns out to be effective.

[0033] Not shown in detail in this diagram are motors that drive the machine in the y and z directions. Linear precision slides are used to allow parts to move relative to each other. These are desirable to minimize sliding friction and to prevent loss of precision for small displacements. Supported by ball bearings to reduce unwanted stiction or static friction A well-lubricated jib is often used when rigidity is required for the slide, and the adjustment pole Allows the point to absorb wear, but small dedicated equipment typically has very low loads In fact, this dedicated device can be used in a wide range of applications, provided it is properly adjusted at the factory. Requires little additional maintenance other than lubrication. The slide is only partially shown. A typical slide is shown later in Figure 3.

[0034] Mounting assembly for mounting a machined component to a three-dimensional movable platform 225 can be adjusted in a series of predetermined steps. The link can be extended or offset in the z-axis, eliminating the need for long z-axis travel. Variable mounts can also be used, but measures must be taken to limit the risk of misalignment or misalignment. One way to achieve this is to adjust this position. Use the same assembly or adjust the stop to prevent further movement of the mounting assembly. This is because the features in the material being machined would otherwise be distorted by the Z-axis movement. This is especially useful when the mount is too large and can be a hindrance to the user's ability to use the device. It can be mounted in various orientations, allowing machining to be performed in non-normal positions. , as shown in detail in Figure 4A. This allows, for example, A feature can be cut into the vertical portion of the test sample. If the machine is large enough to accommodate the load and is not too large to strain the machine's drive mechanism, The range can be widened.

[0035] The camera 230 is mounted so that it is a defined distance from the machining location. Power and signals are supplied via cable 233. The camera position is determined by machining a point, and then the image of that machined point is located at the center of the graticule. This can be adjusted by manually moving the camera so that it is positioned at the machining action. The difference between the starting position of the camera and the position where the appearance is centered within the camera's field of view is This offset is stored as a computer constant and is used to When visually identified, simply add or subtract this stored constant as needed. By doing so, the machine tool can be moved to that point. A lens hood or shroud 235 may be attached to improve contrast. If desired, a lighting source may be co-located with the shroud or added externally. The light source can be monochromatic or polychromatic. By using light-emitting diodes of various colors, The image quality may be optimized.

[0036] A high-speed motor 240 that drives a cutting tool installed at 247 is attached to a movable platform. The cutting tool moves to the sample and the cutting is programmed and performed automatically. The spindle speed must be high. In one embodiment, this speed is 10,000 to 100,000 rpm. range, so that optimum cutting speeds can be achieved. A mounting device 245 is located at the end of the spindle. In this case, a carbide-tipped end mill is sufficient to perform the machining action, and the cutting The tool is usually determined by the application and the material to be cut. Supplied via.

[0037] Tens of thousands of an inch per cutting pass to eliminate the need for coolant or lubrication at the cutting point ~Very light cuts may occur in the vicinity of a few thousandths of an inch (one application In this case, the optimum cut is about 0.004 inches (or about 100 μm). This means that many passes are required to achieve a reasonable depth that provides accurate information for the The depth of the slots or holes is usually sufficient with a working depth of about 5 mm, but this depends on the material. and other relevant information. Chips that are sunk into the cutting nozzle without or in addition to coolant It can be removed using an air blast on the tool, but this is not an easy task to do as the drawings are cluttered in the illustrations. This is not shown in FIG. 2A to avoid overloading.

[0038] At the high spindle speeds used in this embodiment, significant A current of I is applied to the motor. 2 Both R losses and eddy current or iron losses This heat is not particularly harmful to the motor, but it can be harmful to the operator. The motor is fitted with a shroud 242 through which the airflow is directed, creating a potential burn hazard. This cooling air 250 is filtered to remove any contaminants that may be present. The filter 255 may be plumbed to remove any other air than dry clean air. As it passes over the motor, the residue gets trapped or deposited on the motor housing, causing the motor acts as an insulating barrier that can significantly increase the operating temperature of the Common contaminants from compressed air include water, oil, and debris. It is best to remove all of these. Often, compressed air is available in the factory. A simple air pump is generally sufficient, but these may also interfere with proper operation. It contains dust and dirt particles, so a simple cleaning action is preferable. It can be easily vented around the motor shroud and directed or directed elsewhere. There is no need to do so.

[0039] A strain gauge array, such as that shown in FIGS. 1A and 1B, may include one or more gauge elements. It has large connection pads that facilitate the attachment of wires for connecting the device to measuring equipment. This connection is usually made by soldering a wire to the pad. To facilitate a good electrical connection between the point of connection to the electrical system and to prevent corrosion, During manufacturing, the bond pads may be coated with a thin gold coating to prevent oxidation. The coating is not particularly durable and cannot withstand harsh treatment, but with due care it can be For example, it may be suitable for use in automated probing equipment. This creates an opportunity for a probe station to be attached to the machine in Figure 2A, and machining can proceed. As the tool moves, a probe is applied to the gauge and measurements are taken and recorded at intermediate points in the machining process. As machining progresses, the measured strains are such that further machining does not increase the strain. It asymptotically changes to a value where no significant change occurs. At this point, machining is stopped. This leads to unparalleled efficiency gains. Heavy cuts are minimized and no additional material is added to the part, as opposed to the heavy cuts seen with traditional methods. This is a good strategy because it generates very little stress on the Thrust cutting has been found to be less cumbersome than cutting with a coring drill Coring drills are able to disperse chips even when there is considerable clearance at the cube edge. The material is trapped between the tool body and the material being machined, causing it to peel off on the side of the cutting area. In addition to the risk of chipping, it is very difficult to remove the chips that are generated as a result of cutting. This significantly reduces tool vibration during machining as it is less efficient.

[0040] The measurement probe may be of any suitable type. Such probes are readily available to consumers. Ideally, the probe should be plated with a material that is not susceptible to corrosion, such as gold, palladium, or chrome. Coated to reduce problems and replaceable to allow damaged parts to be replaced The probe station includes a camera 230 and a motor 240. 2B is an exemplary view for a single probe connection. The probe assembly is shown. The contact component 270 is made of a palladium alloy or gold plated. The spring is usually made of a corrosion-resistant material such as a conductor. The contact pin assembly can be pressured to hold the pin in contact with the contact pin. The pin holder 275 is made of a non-conductive material and is attached by a screw 285. The spring 277 is held in place by a fixture 280. The spring 277 ensures safe operation of the probe system. Pin 270 is connected to a measuring device by wire 272. The system is not shown, but this is done by connecting the probe assembly (usually the machining strain gauge (two or more probes may be used depending on the number of strain gauge connections) During use, the probe contact system makes contact with the gauge contact pads. The gauge is moved to the starting position to measure the start value or values ​​of the gauge. During fine tuning, a record of the position of the moving platform is made, which is This may be a manual adjustment, which would be the simplest implementation of this system. and use the camera to center the gauge reference point. The offset between multiple probe positions can be recorded and saved. After a predetermined number of cutting passes, the probe station can be turned off to the gauge or gauge head. and returning the probe to a contact position on the gauge array, extending the probe to contact one or more gauges. If there is no contamination, repeat measurements can be made and the probe Accidental errors in measurements that occur as a result of wear on the contact pads of the gauge due to repeated contact. The controller slightly indexes the probe position to touch a different part of the contact pad. This is easily handled by

[0041] FIG. 3 shows the structure of a slide 300 and a drive mechanism 310. The slide moves along one axis. The slide 300 is designed to move freely on one axis and not move on the other two axes. The slide engages the rail 305 using a tang that fits into the rail. These are adjustable components that can absorb wear. Although it is possible to reinforce parts with reinforcements, in precision machinery such as this, it is necessary to replace worn parts with new ones. In one embodiment, the drive mechanism 310 has a speed of 200 steps per revolution. The stepper motor 320 was selected to have steps of 1.8 degrees corresponding to the step The pitch of the lead screw 325 that drives the slide mechanism is one complete revolution. Then slide 320 is selected to move 1.2192 mm or 0.048 inches. The drive nut 330 is attached to the slide assembly, while the drive motor 320 is attached to the machine body. The drive screw is stabilized in either position or thrust, or both. Bearings that can be installed to allow for this are not shown. 0 is selected to have bearings that can support a significant thrust load. Therefore, the distal end of the drive screw may require little additional support. The same drive components may be used in both the X and Y directions, but They do not have to be the same. The vertical or Z direction is the most accurate way to control incremental cutting. Unless fine pitch is desired for ease of understanding, It can also be done as follows.

[0042] FIG. 4A shows mounting details of the electric cutting motor and its components shown in FIG. 2A. Mount 225 is attached to a three-dimensional movable platform in one of several ways. The mount is indexed by two slots 405. The device is then mounted in one of two ways, in one embodiment: This allows features (mechanism, appearance) to be cut from the bottom up, rather than just from the top down as in the conventional method. Index pins are used and precisely positioned to allow for easy movement of the moving platform. In another embodiment, the mount position relative to the mount is always repeatable. It can be mounted in several positions offset by 90° to allow cutting into the face. In yet another embodiment, the mount can be selectively machined to any orientation. The latter may be driven by a system that allows any angle to be used. This is especially useful when cutting must be done within a range of samples, which would otherwise be difficult to achieve with segmented parts. A significant number of tool setups and jig grindings are required to access the sample being inspected. You will not be able to access it.

[0043] The motor shroud 420 includes an inlet connection 42 that allows an air supply to be attached. 5. Airflow helps remove some heat from the motor, but its primary effect is The aim is to limit the temperature rise of the shroud, preventing the operator from accidentally turning on a hot part. The air is supplied from a compressed air source as shown in Figure 2A. As shown in Figure 4B, the water is taken in from a small pump located near the dedicated device. This air may be filtered by filter 255 as shown in FIG. 2A to remove moisture, The filter outlet is connected to the inlet 425 by a flexible pipe 420. It can be connected to a shroud and does not have to be a high pressure connection. High flow is not required, and the The air is simply vented from the base of the shroud. Debris and insects are removed when the dedicated device is not in use. A screen (not shown) is attached to the base of the shroud to prevent the intrusion of This can be effective if dedicated equipment is used in an orientation that favors particle accumulation under gravity. The screen or screen assembly helps to prevent this. For use with a simple T-fitting attached to a flexible pipe or tubing may be used to draw air from a filtered air supply. The air is bled through the lens shroud attached to the camera using a nozzle (not shown). Blow air across 235 to keep debris and contaminants away from the lens surface. Power for the motor 240 is supplied through a cable 243 .

[0044] Continuing with FIG. 4A, an optical system including a camera 230 is used to image the feature to be cut. It is possible to find the machining point or starting point of the body (mechanism, appearance). Transmission is provided using cable 233. A simple shroud or lens hood 23 5 may be attached to the optical system. This hood is simple and reduces shadows and loss of contrast. It is merely a shield to reduce extraneous light that may cause eye damage. Measurements can be made by physically attaching the device to the hood. Alternatively, measurements can be made by computer generated The resulting reticle can directly manipulate the resolved image on a computer screen. The hood 235 may include a lighting component, and in one embodiment, the lighting may include various The emission wavelength or color is provided by one or more light emitting diodes, which then By switching the power of the light source, the light spectrum can be changed from the relatively long wavelengths of the near infrared to the This can be varied to a relatively short wavelength at the blue end of the spectrum, depending on the material being illuminated and its finish. Thus, the illumination may be monochromatic or polychromatic, which may be advantageously used depending on the Modern image sensors have operating bandwidths that extend well into the infrared spectrum, making it It is useful for imaging the camera and for measuring the temperature and The degree profile may be measured and used as part of the analytical measurement data.

[0045] Figure 4B shows the motors and the camera's optical system, which are supplied with clean cooling air. Air pump 45 is used to provide the air blast for the 5 draws ambient air through tube 450 and sends it through filter 255, The air is then distributed to a dedicated device via tube 420. Pump 455 is electrically It is driven by a motor 460, and power for the motor is supplied to the motor through a cable gland 470. It is supplied using a cable that goes into the

[0046] FIG. 5A shows a camera 230, its power and signal cables 233, a shroud 235, and 5. The reticle 510 is an accurate measurement standard and is used to measure the object to be machined as shown. The image is projected onto the object or engraved on an insert placed inside the shroud. This is a relatively common method used in microscopy, but In metallurgical applications, methods such as specular processing are also useful. The reticle generated by the data is displayed on the display screen and is overlaid with the image of the workpiece. B shows an illumination device that can be attached to the camera shroud. It provides a housing for the lighting components 580. These are light emitting diodes (LEDs). and may be chosen to produce monochromatic light, polychromatic light, or even a selectable range of wavelengths. Power is applied via a connector 585 attached to the body. This lighting component can be installed in various versions as required by the application. This means that modern camera components are very small and can be easily changed for different applications. Therefore, it is clear that it would be practical to embed lighting elements into the camera sensor itself. The camera's resolution is a design choice, as is the lighting method. , a part of the air supplied to the electric motor shroud for machining is taken in and used as the camera This is ensured by directing the jet across the lens area. Particles and debris may be in close proximity to the camera, such as when the device is used to cut backward from the bottom of the specimen. This is advantageous when the dedicated device is aligned so that it falls flat.

[0047] In yet another embodiment, FIG. 6 illustrates a cutting tool 610 secured by a collet 245. They are located in close proximity to each other, allowing operators to directly position dedicated equipment. 5A shows how the camera shroud 235 of FIG. In the same way that the IR-1000 was used, a user-selectable monochromatic or polychromatic light source was used to illuminate the target observation area. In low light operation of the camera, lens constructions have the effect of limiting the depth of field. It is important to understand that wide openings are required for construction. This allows the lens aperture to be smaller, resulting in improved depth of field. By using LEDs as a lighting source, the general incandescent Good intensity can be achieved without the dissipation exhibited by LED light sources. offers the great advantage of being extremely robust, and relatively resistant to mechanical shock and abuse. There is.

[0048] The use of fiber optic cables also allows for the illumination source 630, which may include a camera sensor, to be remotely This is also an opportunity to place the light at intervals using a partially silvered mirror arrangement. By doing so, the fiber optic cable directs the light directly to the viewpoint, while the camera sensor focuses the light onto the mirror. One advantage of this is that off-axis shadows are reduced, This method is similar to the use of borescopes found elsewhere in the art as inspection devices. No electronic controls or extra wiring need to be located where machining is taking place. Therefore, the ability to provide high illumination remotely is beneficial. The reduction in mass at the camera further improves maneuverability and responsiveness. 6, which is enclosed within a housing 630. Preferably, the partially silvered mirror is an integral part of the camera component. The cutting tool 610 is held securely to the motor 240 by a collet 245. The nozzle 605 is used to remove machining debris from the area around the cutting tool 610. The optical fiber cable is connected to the housing of the camera. If included in the device 630, it may be installed in place of a camera or may be used in place of a conventional camera. When combined with the , it can be fixed to illuminate the required area to provide illumination only.

[0049] The system block diagram shows the control that manages the drive motors for the mobile platform 710. A computer 700 is shown connected to electronic equipment 705. A camera interface 715 is , camera system 230 of FIG. 2A (or in the case of an integrated camera and fiber optic cable) 6) so that visual information can be stored and displayed. The constant electronics 720 connects the computer to the probe station 725 and the positioning device. A mechanism 730 is also provided to allow the probe 735 to be extended or retracted. The lobes are adjustable and can be adjusted to fit the strain gauge or gauge array being used in the analysis. It can be placed to connect to 0.

[0050] In one embodiment, a profiling system 750 is provided. In this embodiment, a linear variable differential transistor Use a position sensor such as the Transducer 755 to position the surface of the test strip, coupon, or sample. The surfaces may be tracked and this information may be recorded for later use by the computer during the analysis. As an example, mechanical differences in the profiles can be used in combination with differences in residual stresses to You may want to determine the effect of geometry on critical parts. A display 760 and a keyboard 765 may be provided. pointing devices such as a mouse, joystick, touch screen, or tactile controller Specialized interface components such as controllers are also available to meet customer needs for specific applications. may be provided according to the needs.

[0051] General-purpose computing platforms such as laptops and desktop machines Although application-specific computers may be used, dedicated equipment must be fully customized. In one embodiment, computer control, measurement, and Processing uses external connections for a display monitor and user interface elements. It runs on an embedded single-card computer. The firmware defines how user information is entered and how it is used to control aspects of the dedicated device itself. Decide the law.

[0052] Another aspect of the dedicated equipment is to protect the system from difficult or dirty working conditions. Furthermore, the housing can be used to provide a convenient and easy access for users and personnel near the dedicated device. A typical enclosure is shown in Figure 8. The enclosure frame 800 is the base of the enclosure. One or more doors 810 provide easy access to specialized equipment. In one embodiment, translucent polycarbonate sheets 820 are used for the walls of the enclosure, These can be replaced by opaque metal walls. Enclosures are typically used for portable use in the field. It is divided into two or more main parts for easy access to dedicated equipment, but in practice For fixed use in a laboratory environment, this removability is less important. The modular design allows for easy design changes to accommodate large structures that may otherwise be inconvenient. It can accommodate various constructions.

[0053] In summary, the present invention provides a method for manufacturing materials for components and structures using machining processes. A system and method are provided for analyzing material properties and enabling stress relaxation of materials under test. The advantages of such a system include improved machining accuracy for fixed laboratory use. Improved by the latest technology, it allows you to drill holes, access holes, and more using a single tool without the need for tool changes. Cutting residual stress relief features including all nuclei, slots and slits It enables automatic measurement of the strain state of materials and allows for remote measurement without significantly changing the performance of the equipment. Includes abilities that can be used in locations.

[0054] While the present invention has been described with respect to several embodiments, modifications and variations are possible which fall within the scope of the present invention. , modifications, substitutions, and equivalent alternatives exist. While provided to aid in explanation, these titles are merely exemplary and should not be construed as limiting the scope of the present invention. It is not intended to limit the scope of

[0055] It should also be noted that there are many alternative ways of implementing the methods and apparatus of the present invention. Therefore, the following appended claims are intended to fall within the true spirit and scope of the present invention. and shall be interpreted as including all such changes, modifications, substitutions and equivalent alternatives. It is intended that

Claims

1. A test device having one or more strain gauges mounted along a predetermined axis and A strain measurement system that produces an output proportional to the change in strain when the stress state of a component changes.

1. A method for measuring residual stresses in a component under test operatively connected to a 、 The machining device and the component to be tested are positioned in appropriate relative positions, making an incision in a surface of the component under test; A point determined by the arrangement of the one or more strain gauges is identified, and the material in the vicinity thereof is measured. material is removed from the component under test to alter the existing residual stress at that point; Steps and Starting from said point, with respect to the surface on which said one or more strain gauges are attached machining a feature onto the component under test at a predetermined angle; Thus, the machining can be performed with multiple light machining steps without introducing additional stresses from the machining process. a deep cut, so that the residual stress in the region adjacent to the feature is reduced to the bulk a step that is isolated from the and measuring the change in strain resulting from the machining for use in the calculation. ,method.

2. Inspecting the surface adjacent the area of ​​the intended cut, a profile of the area being recorded. The method of claim 1 further comprising creating a file.

3. The method of claim 2 , wherein the testing includes testing using a linear variable differential transformer.

4. Inspection is optically enabled, including inspection using digitally coded probes. The method of claim 2 .

5. the cut feature is an annulus surrounding the strain measuring component; The method according to claim 1.

6. the cutting feature is a slot cut along the strain measuring component. The method according to claim 1.

7. The method of claim 1 , wherein the measurement system includes a Wheatstone bridge.

8. The measurement of the change in strain includes an optical system using a light source and one or more detectors. The method according to claim 1.

9. 9. The method of claim 8, wherein the light source frequency is selectable to be monochromatic or polychromatic. Law.

10. The strain measurement system uses a camera and performs digital image correlation to measure the strain. The method of claim 1 including an optical system for determining the change.

11. A dedicated device for use in residual stress analysis of a component under test (CUT), comprising: a movable platform having two or more mutually orthogonal axes of motion; a drive mechanism for each motion axis coupled to a control system; a machining tool coupled to the control system, the tool adapted to The component under test (CUT) is subjected to multiple light stresses without introducing additional stress from the a machining face of the component under test configured to machine a small cut, Residual stresses in the region adjacent to the feature are isolated from those in the bulk, thereby a component under test responsive to the residual stresses isolated from the residual stresses in the bulk; configured to measure strain or displacement in the area adjacent to the machined feature of the device. preparing the area adjacent the machined feature for placement of a sensor formed thereon; and an adjustable motor mount for positioning the minimum cutting height of the machining tool. and a camera having a viewing area perpendicular to the cutting axis and fixed relative to the axis; The control system inputs and executes operation commands and parameters, and displays camera images. and a processor and interface that enable the calculation and storage of measured and derived information. Dedicated equipment, including interfaces.

12. 12. The system of claim 11, further comprising a reticle for measuring distances in the display area. Stem.

13. 13. The method of claim 12, wherein the reticle is electronically generated and superimposed on a displayed image. system.

14. A hood attached to the camera lens illuminates the viewing area with monochromatic or polychromatic light. The system of claim 11 including one or more selectable light sources for illuminating.

15. The system of claim 14, wherein the light source is a light emitting diode and includes wavelengths in the near infrared. 。

16. The system of claim 11 , wherein one axis controls the cutting depth.

17. Equipped with a probe station that allows automatic connection to strain gauges or gauge arrays The system of claim 11 .

18. The probes of the probe station are operated independently of the operation of the movable platform. The system of claim 17, wherein the system can revert to a relationship.

19. The system of claim 11 , wherein the machined feature is a slot.

20. The machining features are pre-programmed and conditioned on the input of dimensional data. The system of claim 11 , including one or more selectable shapes corresponding to the manipulation.

21. The one or more selectable shapes may include a hole, an annulus, a slot, a slit, an ellipse, a rectangle, 21. The system of claim 20, including a shape or a plus sign.

22. Adjustable legs are provided for angular adjustment of the cutting tool relative to the area to be machined. The system of claim 11 .

23. The scanning probe is attached to automatically map the component under test. The system of claim 11, wherein the system is capable of pinging.

24. The mapped profile is used to adjust or direct the drive mechanism to the machined features based on the profile of the surface of the component under test.

24. The system of claim 23, wherein the system allows adjustment of

25. The machining tool may comprise a core for holding a drilling tool, a milling tool or a cutting tool.

12. The method of claim 11, further comprising: system.

26. The system of claim 11 , wherein the machining tool utilizes electrical discharge machining.

27. The system of claim 11 , wherein the machining tool utilizes laser ablation. 。

28. The camera and the machining tool are permanently fixed and require manual adjustment during testing.

12. The system of claim 11, wherein no adjustment is required.

29. The system of claim 11 , wherein the sensor is a strain gauge.

30. The system of claim 11 , wherein the sensor is a displacement meter.

31. The sensor may be a strain measurement or imaging device including one or more of digital image correlation and interferometry. The system of claim 11 , wherein the optical method for displacement measurement is used.

32. The system of claim 11 , wherein the machined feature is positioned relative to the sensor. Hmm.

33. 10. The method of claim 1, wherein the machining feature comprises at least two steps along a vertical axis.

2. The system described in 1.

34. 12. The method of claim 11, wherein the at least two steps are dimensionally non-linear with respect to each other. The system described.

35. 12. The method of claim 11, wherein the machined features are located using optical feature recognition. The system described.

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