Abstract: An imaging X-ray sensor is composed of a linear array of microscopically small bars of polycrystalline ceramic scintillator material bonded at the bar ends to an integrated circuit photodetector array. The scintillator bars are the basic resolution elements of the detector and are less than 50 microns in width. Each bar produces a flash of light with intensity related to the X-ray flux penetrating the bar. A reflective coating covering five surfaces of the bars isolates each detector element and channels the light into the photodetector bonded to one end of the bar. A method of fabricating the detector array utilizes the machineability and good mechanical strength of scintillators such as rare earth oxides doped with rare earth activators.

Abstract: Automated grinding is performed using a tracking means having a sufficient field of view to locate edges to be processed and using a high resolution profiler in order to provide grinding information for calculation of the amount of material which should be removed from the workpiece. Those sections of the workpiece not requiring additional grinding may be traversed at a high speed in order to improve productivity. A process control computer receives grinding information from the tracking means and high resolution profiler and uses it to control a manipulator to adjust the travel speed of the grinder, force with which a grinder is applied, position of the grinder, and/or speed of rotation of the grinder in order to remove the correct amount of material from a workpiece. The technique is especially advantageous in removing excess material, burrs, nicks, chips and other minor irregularities in workpieces. A second profiler may be used to check that the grinder has properly ground portions of the workpiece.

Abstract: This ultrasound imspection method using the Born approximation simplifies the problem of characterizing 3-dimensional flaws of general shape by reducing it to a series of 2-dimensional tomographic image reconstructions. The reconstructed 2-dimensional images represent the 2-dimensional projections or shadows of the 3-dimensional flaw characteristic function which specifies the shape of the flaw. Each projection image is reconstructed independently using well developed computerized tomography techniques. If the shape of the flow is not too irregular or fine details are not of interest, only a few of these projection images are needed. The 3-dimensional flaw shape is reconstructed from the 2-dimensional projection images through a 3-D reconstruction process.

Abstract: Precision control over the cutting force during robotic deburring and edge contouring is obtained by use of a "zero spring rate" driver. The driver consists of an air cylinder with a low friction piston. An accumulator is used in between an air supply line and the air cylinder such that the air pressure against the piston is constant. The driver is used to position or move a moving portion of an ultralow friction ball slide relative to a fixed portion of the ball slide. The arrangement avoids inaccuracies in a metal removal process which might otherwise be caused by robot path errors, part setup errors, and robot stepwise motion effects.

Abstract: The weldability of a part formed from an alloy having low impurity concentrations is determined by initiating an arc between a stationary welding torch and the part using a predetermined set of welding parameters selected to produce a partially penetrating molten weld pool. The natural frequency of oscillation of the molten weld pool is measured a predetermined time following initiation of the arc, and the measured natural frequency of oscillation is compared to empirically determined data for the alloy to determine the weldability of the particular part. Variations in trace element concentrations between different heats of the same alloy affect the three-dimensional geometry of the molten weld pool, and in turn affect its resonant frequency. The invention may be used to adjust the welding parameters to accommodate differences in weldability between different heats of the same alloy.

Abstract: Vibrations at the groove cutting tool-workpiece interface are sensed by a vibration sensor such as, for example, an accelerometer, and the vibration sensor output is processed to yield an electrical signal indicative of groove cutting tool cutting noise vibration. Digital analysis of the electrical signal after it is sampled is performed to detect various types of groove cutting tool break event signatures, and especially a type of signature in which a high amplitude positive going spike is followed by a significant shift in the mean amplitude signal level of the background cutting vibration. A machine tool monitor, system and method are disclsoed which detects such changes and interprets them to detect groove tool break events of sufficient magnitude to endanger the machined part.

Abstract: Substantial cutting condition changes which occur in intermittent bursts as rough surfaced workpieces are turned generate specific vibration signal signatures known as the runout condition. Either an upper or a lower threshold is set and all mean signal samples are compared with the threshold value. When the mean cutting noise exceeds the upper threshold or stays below the lower threshold for a preset number of signal samples, a tool break alarm is generated. Techniques are given to reduce false alarms on runout during initial rough surface cuts. The system comprises an accelerometer or other sensor whose signal is processed to attenuate lower frequency machinery noise and to detect the signal energy in a band below 100 kHz, then sampled, and the digitized signal samples analyzed by pattern recognition logic.

Abstract: To control the welding current in a resistance spot welding system, a current measurement sensor is used with a current feedback control to vary the firing angle of power devices in the primary side of the power supply. The closed-loop feedback control assures the desired current is applied independent of variations in the resistance of the welding equipment and primary line voltage variations. In the current feedback control, the commanded current, proportional error, integral error and line voltage offset are summed to derive the firing angle signal, and the power supply is adjusted until actual current equals the desired current.

Abstract: A speed regulator digital speed controller for rotating machinery is comprised of a single-chip microcontroller operating in conjunction with a multiple counter/time peripheral, and is programmed in a high level language. Pulses are generated by a digital speed sensor at a rate too low to give the required speed resolution; these pulses are counted and a preset number toggles a binary gate signal. Two clock counters both having an input connected to a high reference frequency oscillator are gated alternately and accumulate a count depending on the length of the gated on interval. These speed related counts are read during alternating gated off intervals into the microcontroller where the speed error is calculated in real time to a high degree of accuracy and resolution. The speed of an electric motor and a steam turbine, for instance, are regulated.

Abstract: An adaptive feedrate control and method of optimizing the metal removal rate of NC end milling is based on a solid modeler which continuously simulates the in-process workpiece geometry in 3-dimensional machining. For each NC record representing a tool motion, an adjusted feedrate is generated off-line by the simulation running on a general purpose computer. The metal removal rate, cutting force, and tool deflection are calculated, and a feedrate is chosen to increase machine utilization without violating user-set constraints and avoid common machine problems such as excessive tool deflection and tool breakage.

Abstract: Sharp tools have different cutting characteristics from dull or worn tools. Among these differences is that a wear land develops on the cutting tool so that more of the cutting tool comes into contact with the workpiece during the cutting process. The increased contact area between the tool and workpiece forces more energy to be consumed by the cutting machine in making a cut because more energy is expended in non-productive work. Indications of an increase in non-productive work are the increased power or force necessary to operate a spindle in lathes, milling machines, etc., and the increased energy in cutting vibrations in a low frequency range emitted during the cutting process. Another indication of decreased efficiency of the cutting process is the decreased energy in cutting vibrations in a high frequency range emitted during the cutting process.

Abstract: High speed readout is achieved in a triangulation ranger by a coded aperture light detector which provides a direct digital representation of a range or height position. A light spot reflected from the surface is optically spread into a line segment so it can be shared among a number of light detection channels. The line of light falls on a coded aperture in front of a segmented fiber optic bundle and the light transmitted by each channel is led to a separate photomultiplier or solid state detector. Every coded channel is constructed to give one bit of the digital address of the range position, and a reference light value is obtained from another channel. Background and secondary reflections may be filtered out by focusing light scattered from the surface to a spot and passing it through a slit aperture oriented in the plane of triangulation before being spread to a line segment.

Abstract: Coated carbon composite parts to be tested for oxidation resistance are heated in a closed oven filled with an oxidizing atmosphere. During the heat cycle the carbon dioxide content of the oven atmosphere is measured by an analyzer such as a gas chromatograph. These measurements on the amount of CO.sub.2 emitted by the part provide information on the onset of oxidative failure. It forms a nondestructive test when detection of excessive carbon dioxide concentration is used to reduce the temperature and flood the oven with inert gas so the part may be saved and reprocessed. This technique can be combined with conventional weight measurements before and after oxidation to identify the part constituent, carbon composite or protective coating, that failed.

Abstract: An apparatus for monitoring the curing of a fiber reinforced composite plastic which is cured at temperatures of the order of 350.degree. C. and an ultrasonic transducer assembly useful in the apparatus. The transducer assembly comprises a lithium niobate piezoelectric element having anisotropic coefficients of thermal expansion which is mounted on a metal base of the transducer assembly by means of a layer of structured copper. The structured copper is thermo-compression diffusion bonded to the lithium niobate element and to the metal base, and is compliant in a transverse direction to compensate for differential thermal expansions while affording good electrical and thermal conductivity and good acoustic coupling between the lithium niobate element and metal base.

Abstract: A break or leak in an optical fiber transmitting high power laser energy, at average power levels sufficient for material processing, is detected promptly and the laser beam delivery system shut down when the optical fiber begins to fail. Photo detectors monitor the laser power out of the fiber and injection power into the fiber, in particular the light intensities in the fiber input and output couplers. A difference in detector outputs, larger than a set threshold to account for inherent fiber losses, is an indication that a break or leak has occurred.

Abstract: A tool break detection system has an automatic gain control to adjust the analog signal channel gain and hold the cutting vibration signal at a desired average level. The AGC time constant is long enough that the detection of abrupt tool breaks and sudden large signal level transistions by the digital signature recognition logic is unaffected. However, the gradual decrease in signal level produced by a crumbly-type break would be removed by AGC action. In a system with a hardware AGC, crossing a high gain threshold resets gain to a low value and the resulting abrupt and persisting change in signal level is detected by the abrupt tool break logic. Another embodiment uses the gain command output by a software AGC and generates a break detected signal directly, without resetting the gain command, as gain rises above a high gain alarm level which is recalculated at the start of each cut.

Abstract: A method of digital automatic gain control does the required circulation without numerical multiplication or division and makes possible fast process control using a digital AGC. A signal channel has a digitally programmable variable gain device such as a multiplying digital-to-analog converter; the gain control input of the variable gain device is adjusted periodically to keep the exponential average of the digitized channel output signal with a given time constant at a desired average signal level. For instance, the vibration signal generated by a cutting process is held at a desired average prior to vibration pattern analysis to detect tool breakage and tool touch to a workpiece.

Abstract: A dark field ultrasonic transducer is constructed with an outer annular spherical or conical transducer element and an inner spherical element. The outer annular element is excited and insonifies a small portion of a part surface near a discontinuity or crack with longitudinal waves or with surface waves. The inner dark field element is not focused to be sensitive to either reflected sound or waves reradiated from the surface waves, but detects sound scattered from surface discontinuities such as a crack edge. When surface waves strike a crack edge and restrike it after reflection from the bottom of the crack, two pulses are received and the time delay between them is a measure of crack depth. The crack shape and crack depth profile are determined as the part is scanned. A sphere-cone transducer, the preferred embodiment, is fabricated by stretching thin piezoelectric polymer film over a tool having a ball embedded in a conical surface.

Abstract: An optical sensor head has deep, pitched grooves or screw threads in the walls of the gas channel, and a gas flow swirled along the grooves to protect optics against atmospheric debris and moving particles such as is generated by an industrial process. The grooves are pitched to support swirling motion of the gas. Use of swirled flow increases allowable flow velocity and diverts incoming particles toward the channel walls. The windows of an optical profiler, for instance, are protected against the smoke and weld spatter created by a metal-inert-gas welding torch.

Abstract: The initial contact of a rotating milling tool to a workpiece is detected in the presence of spurious noise spikes by digitally processing samples of a preprocessed vibration signal concurrently through basic tool touch detection logic and milling tool touch detection enhancement logic, and generating a touch indication if either logic set is satisfied. The basic logic detects a continuously increasing signal level higher than a threshold set above background noise. The milling logic detects an above-threshold signal sample and sets up an acceptance window about the expected time of contact of the next cutter. Tool touch is declared when an above-threshold signal occurs during the window; the milling logic is reset by a noise spike in the interval before the window starts. The basic logic detects tool touch in a dense spiky noise situation.