Machines for balancing mechanical parts:

90.31 - Measurin or checking instruments, a pliances and machines, not specified or included e sewhere in this Chapter; prof,Be projectors (+). f - Machines for balancing mechanical parts 903 1.20 - Test benches 903 1.10 - Other optical instruments and appliances : 9031.41 - - For inspecting semiconductor wafers or devices or for inspecting photomasks or reticles used in manufacturing semiconductor devices 903 1.49 - - Other - Other instruments, appliances and machines 9031.90 - Parts and accessories 903 1.80 h addition to rofile projectors, this headin4 covers measuring or appliances an machines, whether or not ophcal. It should, however, does not include any instruments, apparatus, etc., falling in headings to 90.30; in particular, the following are therefore excluded : 'f (a) Astronomical instruments of heading 90.05. (b) Microscopes (heading 90.11 or 90.12). (c) Surveying, etc., instruments and appliances of heading 90.15. (d) Instnunents for measuring length, for use in the hand (heading 90.17). (e) Medical, surgical, etc., instruments and appliances of heading 90.18. (f) Machines or appliances for testing the mechanical properties of materials (heading 90.24). (g) Flowmeters, etc., of heading 90.26. (h) Instruments and apparatus for measuring and checking electrical quantities and instruments and apparatus for measuring or detecting ionising radiahons of heading 90.30. (ij) Automatic regulating or controlling instruments and apparatus (heading 90.32). (I) MEASURING OR CHECKING INSTRUMENTS, APPLIANCES AND MACHINES (A) These include : (1) Machines for balancing mechanical parts (dynamic,,static or with an electronic balancin device) e.g., armatures, rotors, crank shafts, connecting rods, propeller shafts, wheels, ywheels. In dynamic machines, the parts are rotated on two bearing blocks or between centres, the out-of-balance being measured mechanically (tracing of diagrams on a recording plate, spring balance principle, etc.). Static balancing machines o erate on the tilting principle, the out-of-balance being measured on scales or dials. !hey differ from dynamic machines in that the part to be balanced does not rotate. Out-of-balances are compensated either by countenweights or removal of material. On machines fitted with an electronic balancing device, the vibrations due to unbalance are detected by a special sensitive element and are then amplified. This headin also covers balancing machines fitted with a machine-tool (drilling-machine, for exampleyand used exclusively for rectifjmg out-of-balances. (2) Test benches for engines and motors, electrical generators, pumps, speed indicators or tachometers, etc., consisting of a frame and a measuring or calibrating instrument. (3) Laboratory ap liances of a kind used for testing fuels and in particular for measuring the octane index o petroleum or the cetane index of diesel engine oils. This apparatus usually consists of an internal combustion engine, a dynamo, an ignition generator, heating resistors, measuring instruments (thermometers, pressure gauges, voltmeters, ammeters, etc.). P (4) Apparatus for testing and regulating vehicle -motors, for checking all parts of the ignition system (coils, sparking plu s, condensers, batteries, etc.), for ascertaining the best carburettor setting (by analysing ex aust gases), or for measuring the compression in the cylinders. % (5) Planimeters, for measuring plane areas (e. ., on plans, diagrams, skins or hides). A tracing point combined with a measuring device fo lows the outline of the area to be measured. f Integrators, harmonic analysers and other instruments are based on the planimetric principle and capable of measuring other factors (e.g.,volume, moments of inertia). (6) Head contour measurers, used by hatters, which operate by perforating a sheet of paper. (7) Dial indicating corn arators, micrometric devices, electronic, opto-electronic and pneumatic sensors, w ether or not automatic, as well as a11 devices or instruments for measuring length, angles or other geometrical quantities usin such sensors. The heading also includes recording corn arators, and comparators fitte with a mechanical device which conveys mass produce parts to the comparator and eliminates defective parts. 'k B f However, this headin does not include the dial type corn arators for use in the hand described in Item (4) of Part (D) ofthe Explanatory Note to headng 90. f7 (see exclusion (d) above). (8) Column-type gauges for checking precision set squares, for checking heights or for other checks during manufacturing processes. (9) Sine bars and adjustable table sine bars for checking angles. (10) Bubble levels, used in numerous trades, includin micrometric ad'ustable levels (bubble level with built-in micrometer), block levels fmetal frame wit two levels) used in engineering, and liquid levels based on the communicating vessels principle. h It should be noted that the heading excludes levels specialised for surveying purposes (heading 90.15). (1 1) Clinometers (yointer or graticule t es, clinometer-rules, clinometer-protractors) to check a level as compared with a horizonta plane, or to measure surface inclmation. However, the instruments, also called clinometers, used in surveying to gauge the height of land, are excluded (heading 90.15). (13) Spherometers to measure the curvature of s herical surfaces (lenses, mirrors, spectacle lenses, etc.). These consist essentially of a ase with three pins (at the angles of an equilateral triangle), a divided rule and a micrometric screw with feeler. Other types 'i (opticians' lens measurers) may be fitted with a dial to indicate the curvature directly. (14) Checking standards. (15) Multidimensional measuring equipment, including Co-ordinate Measuring Machines (CMMs) used to perform dimensional checks, either manually or mechanically, on various components or parts of machines. (16) Opticians' centring machines for determining and marking the axis and centre of a lens. (17) Micrometric standard measuring machines, based on the micrometer principle. These consist of a fixed tailstock (with a contact indicator) and an adjustable headstock with micrometer screw. (18) Apparatus for measuring or detecting vibrations, expansion, shock or jarring, used on machines, bridges, dams, etc. (19) Apparatus for checking textile materials, for example, yarn radin winding reels (warp ree s), for obtaining a determined length of yarn or slivers, (wit or w out tension re counter and bell); torsiometers and torsiographs for determining torsion o!?lator9 yarn; tensiometers for measuring tension of yarn on textile machines (warpm spool winding, spinning, etc.); instruments for checking the regularity of yarn by win ng on a drum or board, usually comprising a device for checking the interval between windings. % -L & (20) Surface-finish testing instruments and machines for gauging the condition of surface. In mechanical or pneumatic types the gauging is done by means of a hard contact point or air jets. In electrical types a sapphire or diamond pick-up moves across the surface to be tested and converts any irregularities of that surface lnto an electric potential. The ;vertical movements of the ick-up are converted into the electric potential by means of a piezo-electric crystal or, in irectly, by bein made to vary the value of a capacitor or inductor. The electric potential is then ampfified and measured. Comparison of the measurement with the readings obtained by use of selected surface roughness standards (small metal plates supplied for that purpose) give a measure of the state of the surface being tested. (21) Gear testing machines using, for example, a lever amplifying system, for testin profile forms, pitch diameters, tooth spacing and rolling contact, etc. (on spur and beve gears), lead, etc. (on helical and worm gears). f (22) Instruments for measuring the contractin of a clay, etc., test iece taken from a ceramic furnace during f i n g to determine tfe course of the firing &roscopes). These instruments are often slrnilar to callipers but are calibrated in arbitrary units. (23) Instruments for measuring irregular surfaces (such as skins and hides by the hotoelectric process. (The dfferences in the current fiom a photoelectric cell epend on !ow much of a uniformly lit glass sheet is covered by the opaque surface under measure.) d (24) Instruments for measuring the diameter of yarns by the photoelectric process as described in Item (23) above. (25) Instruments for continuous measurement and checking of the thickness of metal sheets or strip in rolling mills, etc. (26) Ultrasonic thickness measuring instruments which enable thickness to be ascertained by observations made from one side of the material only. (27) Instruments for detecting faults, fissures, cracks or other defects in materials (bars, tubes, profiles, machined articles, such as. screws, needles, etc.). These operate either by observing the cathode-ray screen diagram resulting from magnetic variations, or by direct readin of variations in ma etic permeability as indicated on a graduated scale or by the latter group includes ultrasonic instruments for checking use o ultrasonic waves. soldered or welded joints, which operate on the princi le that any lack of continuity in the medium through which the ultrasonic waves pass gflects the beam. Defects may be measured by either observing the attenuation of the beam or by echo methods. The observation may be made on a cathode-ray tube screen. ? a (28) Special instruments for checking watches or watch parts. These include : (i) Instruments for checking hairsprings. (ii) Amplitude meters for checking the amplitude of the oscillations of the balance wheel. A light beam, which is interru ted by the movement of the balance wheel, is projected on to a photoelectric cell whic thus gives a measure of the amplitude. g (iii)Oscillorneters for testing and checking complete watch movements. The watch movement is laced on a microphone, and each tick of the watch produces a potential which is mpified and applied to two electrodes. One of the electrodes is fitted with points which thus perforate a record on a paper strip. (iv)Instruments for the final check of the watch. These operate on the same principle as oscillometers (recording the ticking of the watch placed on a microphone) but may also be fitted with a cathode-ray oscilloscope. (29) Special electrical instruments for measuring stress and strain. They are based, for example, on the following principles : (i) Variations in the resistance of a wire when subjected to stress (strain gauges). However, electrical resistors known as " strain gauges " fall in heading 85.33. (ii) Variations of capacity between specially constructed electrodes. (iii)Electric potentials produced by quartz or similar crystals when subjected to pressure. This group also, includes dynamometers, used to measure the compression or tractive force of hydraulic presses, rolling mills, material testin machines, etc., and also for load tests (aircraft). They usually consist of a metal body (cy inder, ring, etc.) to which stress is a plied, and of a measuring a aratus, graduated in units of weight, which records any c ange in the shape of the meta!?\ody. Y R However, dynamometers for testing the properties of materials are excluded (heading 90.24). (30) Load cells which convert changes in ap lied force changes in voltage. These changes in vo tage are measuring, controlling, weighing, etc., and are S (31) Electronic chronographs and chronoscopes for measurin the duration of an electric resistance whilst the contact. These consist of a capacitor which is char ed thou& contact is closed; the measurement is made on a va ve voltmeter call rated in time units. B ""P This heading also covers optical type measuring and checking appliances and instruments, such as : (1) Optical or graduated scale comparators, for checking the dimensions of a art being manufactured against a standard piece; the movement of the feeler is magni led by an optical device (revolving mirror principle). P (2) Comparator benches for checkin elongation, lengths, surfaces, etc. These incorporate table and frame, sliding carriage an two mounted micrometric microscopes. % (3) Measuring benches for large parts, thread auges, gear cutters, threaded shafts for lathes, cross members, etc. These mncoporate kame and table, viewing microscope, two micrometric microscopes and projection apparatus. (4) Interferometers, for checking plane surfaces. These are based on the principle of light interference, and comprise a standard optical flat and lenses with micrometric cross wires for measurin the interference bands. But the heading excludes standard o tical flats (heading 90. I), and interferometers for measuring refractive indices (heading 0.27). B % (5) 0 tical surface testers, for gauging the condition of surfaces by means of a combination o a prism and a lens. P (6) Apparatus e uipped with rapid impulse differential feeler and o tical viewer, for photographica ly recording and measuring profiles and conditions of sur aces. P (7) Alignment telescopes, for checking straightness of benches or machine slides and measuring metallic constructions. They are operated by collirnation or auto-collimation and comprise a telescope and a collimator or mirror. (8) Optical rules, for measurin deviations from the plane; they incorporate a hollow rule with a prism and leas at each e n 2 and an eyepiece micrometer incorporating a feeler. (9) Micrometric reading apparatus for checking movement of tables of machine-tools; they incorporate a rnicrometnc device for reading off millirnetre graduations on individual. scales. for checking sharpening angles of teeth or blades etther an optical device with lens and or a shutter system forming a (I 1) Focimeters, for taking measurements of spectacle lenses. The apparatus and instruments mentioned above remain classified in this heading whether or not they are suitable for mounting on machines. It should, however, be noted that heading 84.66 covers fittings for ad'usting the work or tools on machine-tools or water-jet cutting machines, includm " optical '' fittings (J,.%.? '' optical " dividing heads and " optical " circular tables) incorporating optical evices to assist in readtng scales, in carrylng out adjustments, etc. 'f (II) PROFILE PROJECTORS Profde projectors, used for checking the sha e and dimensions of a wide variety of objects @ieces cut to shape, gears and pinions for smalf-sized mechanisms, screws, screw-taps, chasers, etc.), or for examining surfaces. In the majority of these projectors, light from a lam is concentrated into a beam by a condenser before being directed on to the specimen, whic% is placed on a stage. The spectmen is silhouetted in the beam which, after being reflected several times, is finally projected, by a set of prisms, on to a screen which is generally built in to the projector. Some of these projectors are fitted with an intermediate stage on which a standard part is placed. PARTS AND ACCESSOFUES Sub'ect to the provisions of Notes 1 and 2 to this Cha ter (see the General Ex lanatory Note), the eading also covers parts and accessories identi table as being suitable or use solely or principally with the machines, a paratus and instruments described above, e.g., planimeter arms, stands and checking tables or dial comparators. h P ?