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WO1997012197A9 - Appareil de mesure universel fixe - Google Patents

Appareil de mesure universel fixe

Info

Publication number
WO1997012197A9
WO1997012197A9 PCT/US1996/015428 US9615428W WO9712197A9 WO 1997012197 A9 WO1997012197 A9 WO 1997012197A9 US 9615428 W US9615428 W US 9615428W WO 9712197 A9 WO9712197 A9 WO 9712197A9
Authority
WO
WIPO (PCT)
Prior art keywords
base plate
holes
brackets
elevation
pins
Prior art date
Application number
PCT/US1996/015428
Other languages
English (en)
Other versions
WO1997012197A1 (fr
Filing date
Publication date
Application filed filed Critical
Priority to AU73734/96A priority Critical patent/AU7373496A/en
Publication of WO1997012197A1 publication Critical patent/WO1997012197A1/fr
Publication of WO1997012197A9 publication Critical patent/WO1997012197A9/fr

Links

Definitions

  • This invention pertains to accurate installation of bushings in holes provided in structures for that purpose, and more particularly to a method and apparatus for extremely precise installation of bushings in a base plate of a measurement fixture having assorted accessory elements that can be mounted on the base plate for accurately locating a part in a fixed and known position so that measurements can be taken from reference positions on the fixture to the part, which measurements can be converted to virtually any dimensions of the part that are of interest.
  • the measurements provided by a coordinate measuring machine are usually accurate to the degree of precision needed for most applications when they are obtained from a machine that is properly calibrated and operated.
  • coordinate measuring machines are large and expensive, so most manufacturing operations can afford to have only one or very few of them.
  • the parts must be sent to the coordinate measuring machine and measured there by its expert operators. This usually creates a delay before the measurement data is made available, which could affect the currency of the quality control efforts for that part.
  • each manufacturing unit m which parts are made would have its own measurement device so that the critical measurements could be made on the parts made in that unit and that information could be made available to the machine operators in the unit, so corrections could be made immediately if the part dimensions began to drift toward an out of tolerance condition. Also, current information could be maintained and posted on the statistical nature of the part dimensions so the machine operators making the parts, and their supervisors, could be informed about the variations in the parts made by different operators, so corrections to the process or individual procedures of the different operators could be made on a timely basis.
  • This invention uses a base plate having bushings mounted accurately m vertical holes, m which hold-down devices are engaged to accurately locate and secure brackets.
  • the part to be measured is positioned at a known location on elevation pins fastened nto the bushing in the base plate, and against stop-pins mounted in other bushings in the brackets, and measurements are taken with digital indicators in the brackets.
  • the accuracy of the fixture is dependent on the accuracy of the positioning and location and angle of the bushing axis.
  • a universal measurement fixture and a process of making selected dimensional measurements on a part wherein a first datum of the part is located by contact with three fixed points set on the fixture, a second datum of the part representing a line orthogonal to the first datum is located against two fixed points set on the fixture, and a third datum of the part offset from the first and second datums is located against a third fixed point on the fixture.
  • This positioning locates the part in a unique position and orientation in space relative to the fixture. Hold-down devices may be used where necessary to hold the part against the fixed points on the fixture.
  • Accessory elements such as right angle brackets fixable at selected known positions on a base plate, and bridge plats across the tops of angle brackets spanning the part, have receptacles for measurement gauges, such as a conventional digital indicator, by which measurement may be made from the known position of the accessory element to the part.
  • measurement gauges such as a conventional digital indicator
  • FIG. 1 is a perspective view from above of a universal measurement fixture in accordance with this invention
  • Fig. 2 is an enlarged perspective view of the universal measurement fixture shown in Fig. 1 with the part and bridge removed for clarity of illustration;
  • Fig. 3 is a sectional elevation on a vertical plane through the axis of one of the receptacles in the base plate, showing a bracket fastened to the base plate with a hold-down bolt;
  • Fig. 4 is an sectional elevation like Fig. 3, but showing a cam-action hold down device instead of a bolt;
  • Fig. 5 is a perspective view of the universal measurement fixture shown in Fig. 2, showing a hypothetical part located against stand-off pins and digital indicators in the brackets;
  • Fig. 6 is a sectional elevation of a stop pm m a hole in the upstanding flange of a bracket
  • Fig. 7 is an enlarged perspective view on a stop pin shown in Fig. 6;
  • Fig. 8 is a perspective view of the universal measurement fixture shown m Fig. 5, showing a bridge element spanning the tops of two brackets, and a digital indicator taking a vertical measurement to the part;
  • Fig. 9 is a perspective view of the universal measurement fixture shown in Fig.l, but with bridges supported on support blocks fastened to the brackets;
  • Fig. 10 is a perspective view of an elevation pin for supporting the part at the desired height on the base plate;
  • Fig. 11 is a perspective view of a sweep fixture and two locator devices for positioning a part on the universal measurement fixture shown in Fig. 1;
  • Fig. 12 is an enlarged perspective view of the sweep fixture shown in Fig. 11;
  • Fig. 13 is a schematic elevation of a base plate blank positioned over a base plate master in preparation for installation of the inserts in the blank;
  • a universal measurement fixture in accordance with this invention having a thick steel base plate 50, on the order of about 1-3" thick, having a matrix of receptacles 52 opening in the top surface of the base plate 50.
  • the base plate 50 could also be made of other materials to suit the requirements of the user. For example, if aluminum parts are the primary articles to be measured on the fixture, the base plate could be made of aluminum to match the coefficient of thermal expansion of the aluminum parts, thereby simplifying the calculations to account for differing CTE of the parts and the measurement fixture.
  • Granite and graphite/epoxy are two other materials contemplated for the base plate 50.
  • the receptacles 52 are positioned very accurately at regular intervals, for example, every 2" in an orthogonal pattern, over the surface of the base plate 50.
  • the receptacles 52 are numbered along one axis and are lettered along an orthogonal axis to provide a unique identifier for each receptacle on the base plate 50.
  • Each receptacle 52 is configured to receive and hold various hardware items such as stand-off pins and hold- down devices that are inserted into the receptacles, as will be explained in more detail below.
  • Brackets 54 are provided for attachment at selected positions onto the base plate 50.
  • Each bracket 54 includes a base flange or sole plate 56 and an upstanding flange or upright wall 58 attached to an inner end of the base flange 56 at 90° thereto.
  • the upstanding flange is connected to or integral with a buttress 60 at the inner end of the base flange 56 for stiffening against deflection m use.
  • a plurality of holes 62 is provided in the base flange 56 of the brackets 54.
  • the holes may be m any suitable pattern, but m this preferred embodiment are in a regular pattern of equally spaced holes in a 7X7 matrix on 1/2" centers shown in Fig. 1.
  • the rows of holes are numbered from one edge, and the columns are lettered from an orthogonal edge.
  • each of the holes 62 has a smooth-bored insert 63 fixed in the hole on a vertical axis at precisely spaced dimensions from the other inserts, using the process for installing the inserts described below.
  • the inserts 63 receive hold-down devices for holding the brackets 54 down at selected locations on the base plate 50.
  • the hold-down devices include bolts 64, shown in Figs.
  • the hold-down devices could also be conventional cam-action grippers 68, shown in Fig. 4, which have split rings 71 around a shank that is pulled by a cam 69 on the end of a lever to radially expand the rings 71 and grip the smooth sides of a counter-bore 70 in the receptacles 52 above the threaded portion 66.
  • the counter-bore 70 is preferably in a hardened insert 72 set into a hole 74 drilled accurately through the base plate 50. The technique for accurately locating the inserts 72 in the holes 74 is described in detail below.
  • a pattern of holes 76 on parallel horizontal axes is drilled in the upstanding flange 58 of each bracket 54, and a smooth bored insert 78 is set into each hole.
  • One axis for example the vertical columns of holes, are numbered from the top, and the other axis, the horizontal rows of holes, are lettered from the left.
  • the pattern of holes is in a 6X7 matrix lettered A-F across the top and 1-7 down one edge. Any particular hole can then be designated by a single letter/number designator to make set-up and measurement instructions easy to write and follow, in the same manner as the receptacle designators on the base plate 50.
  • each insert 78 is very accurately made with a precisely known internal diameter, and the insert is located in the hole 76 on a known horizontal axis to a very small tolerance.
  • the bore diameter is sized to receive, with a small clearance, a stand-off pin 82 or the shaft 84 of a digital indicator probe 86, as shown in Figs. 1 and 5.
  • Suitable digital indicators are widely available from several sources, such as Mitutoyo. Conveniently, a digital indicator probe 86 with a signal generating and transmitting unit is preferred so that the reading from the digital indicator can be read and recorded on a digital recorder automatically by a push of a button.
  • the locator pin 82 shown in Fig.
  • the pin 82 includes a cylindrical shank section 90 having a diameter just slightly smaller than the inside diameter of the insert 78 so that the pm shank 90 slides with a small clearance into the bore 80 of the insert 78.
  • a threaded section 92 of the p 82 receives a nut 94 which holds a head 96 of the pm 82 against the back side of the upstanding flange 58 of the bracket 54.
  • the p has a shaft portion 98 extending beyond the threaded section 92 and terminates in a rounded hardened distal end 100 which contacts the part to be measured.
  • the locator pms are conveniently provided in several standard lengths from the reference surface, that is, the underside of the head 96, to the end 100, for ease of set-up.
  • the locator pms may also be adjustable by standard micrometer type adjustment so the stand-off distance from a bracket 54 can be set at any desired length with the range of the adjustable length locator pm.
  • a bridge beam 102 shown Figs. 1 and 9, is provided for attachment to reference surfaces, such as the tops of the upstanding flanges 58 of the brackets 54 as shown in Fig. 1, or the tops of blocks 106 as shown in Fig. 9.
  • the bridge beam 102 has a pattern of holes 104 like the holes m the brackets, which preferably are all provided with hardened inserts like those set into the brackets 54. Vertical measurements may be taken from the bridge beam 102 to the part using digital indicators 86 as shown Figs. 1 and 9.
  • the bridge beam 102 may be mounted on a support block of known dimensions lying on the base plate 50, or on another support block 106 fastened at a known position to the upstanding flange of the bracket 54 by bolts, as shown m Fig. 9.
  • Elevation pms 108 shown Figs. 1,2, 5 and 10, have a threaded end 110 and a cylindrical shank 112 depending from an enlarged diameter body portion 114.
  • the elevation pm is inserted into a selected receptacle 52 and the shank 112, whose diameter closely matches the inner diameter of the insert 72 which very accurately locates the position and orientation of the elevation pm.
  • the threaded end 110 is screwed into the threaded portions 66 of the receptacle 52 and turned with a certain torque by engaging a torque wrench with one or more holes 118 in the body 114.
  • a hole 120 accurately drilled the top of the body 114 can be used to locate holes the part on top of the elevation pm, and can also receive an extension pin to add a standard increment to the height of the pin 108.
  • the sweep has a vertical pin 124 (shown m Fig. 12A) that fits closely into a selected receptacle.
  • the pm 124 is attached to a base 125 coaxially with a vertical cylinder 126 having a hole in which the shank 84 of a digital indicator 86 is inserted.
  • the sweep 122 may also be used to measure the distance to the center of a hole in the part P.
  • a self centering pm 128 is fitted mto the hole in the part, and a closely fitting bushing 130 is placed onto the self-centering p 128.
  • the outside diameter of the bushing 130 is known exactly, as is the radial thickness of the cylinder 126 and the distance from the cylinder 126 to the bushing 130 is measured by the indicator 86.
  • the addition of the measured distance plus the radius of the bushing 130 and less the radial thickness of the vertical cylinder 126 on the sweep 122 gives the distance of the centerline of the hole m the part from the selected reference on the base plate.
  • the part P is held against a reference surface 134 of a locating fixture 136 by a spring loaded p 138 on a hold-down device 140.
  • the locating fixture 136 has circular disc 142 attached coaxially to a cylindrical base 144, which is mounted at desired locations on the base plate 50 by threading a threaded extension of a pin, like the bolt 64, into a selected receptacle 52 in the base plate 50.
  • the radius of the circular disc is known to a high degree of accuracy, thereby enabling the accurate location of the part P on the base plate 50.
  • the hold-down device 140 has a cylindrical locating pin projecting from the underside of a base 146.
  • the diameter of the locating pin closely matches the diameter of the inserts 72 in the base plate 50, so the hold-down fixture 140 stays in place when fitted into the selected insert despite the spring force exerted by the spring loaded pin 138 against the part P.
  • the positioning of the inserts in the base plate and the brackets is important to the accuracy of the universal measurement fixture. Extreme accuracy is normally very expensive, but extreme accuracy is possible using the procedure described below at a reasonable cost. The major expense is in the manufacture of a master from which the other elements of the universal measurement fixture are made. The precision of the elements is a function of the precision of the masters, so they must be made to the highest precision. However, once they are made, they can be used indefinitely to make additional copies, so the cost can be amortized over a great many elements.
  • the holes in the element blank are drilled a few thousandths oversized, for example .003" over sized.
  • the blank plate 50B is laid on the master, as indicated in Fig. 13, and an insert 72 is placed loosely in the oversized hole.
  • a locating mandrel 150 is slid through the insert and into the accurately drilled and ground hole in the master plate 50M.
  • Adhesive is poured into the space between the insert 72 and the walls of the hole in which it is place, and the adhesive is permitted to cure.
  • the locating mandrel holds the insert securely in place while the adhesive cures and afterwards may be extracted, leaving the accurately located insert 72 fixed in place.
  • the mandrel can be a helically cut expanding collet 152 on a tapered locating pin 154.
  • a lap used for very accurate grinding of holes.
  • the lap may be slightly tapered and the locating pin on which it is mounted may have the same taper, so that the axial position of the tapered pin in the tapered lap helix determines its diameter.
  • the helical configuration ensures that the bore of the insert and the hole of the master are engaged uniformly by the lap so its axis remains coincident to an extremely high degree of accuracy with the axis of the hole.
  • the adhesive can be may types, but the preferred adhesive is a cyanoacrylate available from 3-M Corporation, Pacer Technology, or Hernon. Epoxy adhesive is also a preferred material for setting the inserts 72 in the holes in the blank plate 50B
  • Set-up is preferably, but not necessarily, done with the aid of computer modeling which specifies the location for the brackets and the locations and heights of the elevation pins.
  • the computer model specifies the location for the digital indicator and calculates the part dimensions from the digital indicator measurements. If these calculations are done manually, they are slower but not complicated.

Abstract

La présente invention concerne un appareil de mesure universel fixe destiné à mesurer une pièce. Cet appareil comporte une platine de base (50) dont la face supérieure plane présente des trous (52) formant un motif régulier. Autour de la pièce, des pattes de fixation, montées de façon sélective sur la platine de base, chaque patte étant constituée d'une semelle (56) pourvue de trous verticaux (62) formant un motif régulier et par lesquels il est possible de fixer la patte de fixation sur la platine de base en des emplacements connus avec précision. Cette semelle est raccordée, sur la longueur de l'un de ses bords à une paroi verticale (58) formant avec elle un angle de 90° et pourvue de trous (76) formant un motif régulier pour recevoir des broches (82) de positionnement et des appareils de mesure (86). Des broches de rehaussement (108) fixées dans les trous de la platine de base permettent de soutenir la pièce à un niveau de référence au-dessus de la platine de base. Sur chaque broche de rehaussement, une surface de référence (115) voisine de l'extrémité inférieure et présentant un écart connu avec exactitude par rapport à l'extrémité supérieure, s'appuie sur une surface de référence de la platine de base, plaçant ainsi avec exactitude, à la verticale, la broche de rehaussement sur de la platine de base, la surface de référence de la broche définissant, au-dessus de la platine de base, un niveau de référence constitué par les extrémités supérieures des broches de rehaussement destinées à soutenir la pièce à une hauteur de référence. Des broches de positionnement s'adaptant dans les pattes de fixation permettent de positionner la pièce à une distance connue à partie des pattes de fixation. Un appareil de mesure est introduit de façon sélective dans des trous sélectionnés de la paroi verticale d'une patte de fixation sélectionnée de façon à positionner avec exactitude l'appareil de mesure en un emplacement connu sur la platine de base de façon à mesurer l'écart avec la pièce placée entre les pattes de fixation.
PCT/US1996/015428 1995-09-28 1996-09-26 Appareil de mesure universel fixe WO1997012197A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU73734/96A AU7373496A (en) 1995-09-28 1996-09-26 Universal measurement fixture

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US436995P 1995-09-28 1995-09-28
US444495P 1995-09-28 1995-09-28
US60/004,369 1995-09-28
US60/004,444 1995-09-28

Publications (2)

Publication Number Publication Date
WO1997012197A1 WO1997012197A1 (fr) 1997-04-03
WO1997012197A9 true WO1997012197A9 (fr) 1997-06-05

Family

ID=26672905

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/015428 WO1997012197A1 (fr) 1995-09-28 1996-09-26 Appareil de mesure universel fixe

Country Status (2)

Country Link
AU (1) AU7373496A (fr)
WO (1) WO1997012197A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004010033A1 (de) * 2004-03-02 2005-09-22 Dr.Ing.H.C. F. Porsche Ag Messeinrichtung
DE202010010011U1 (de) * 2010-07-08 2010-10-14 Procon Gmbh Maschinen- U. Industrieanlagen Werkstück-Haltegestell
CN102359751B (zh) * 2011-08-27 2013-04-24 溧阳市科华机械制造有限公司 检测egr阀六面上各孔位置度精度的专用检测工具
DE102014106293B4 (de) * 2014-05-06 2016-06-23 Bremskerl-Reibbelagwerke Emmerling Gmbh & Co.Kg Prüfgerät und Verfahren zur Prüfung von funktionsrelevanten Merkmalen von Scheibenbremsbelägen für Schienenfahrzeuge
CN105115382A (zh) * 2015-09-09 2015-12-02 广西玉柴机器股份有限公司 油泵托架的检具
DE102022201272A1 (de) * 2022-02-08 2023-08-10 Zf Friedrichshafen Ag Aufnahmevorrichtung zum Aufnehmen eines beliebig geformten Objekts

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3188078A (en) * 1963-06-18 1965-06-08 Kermit M Peterson Micrometer workpiece guide means for die presses
US3723927A (en) * 1969-05-05 1973-03-27 Gen Dynamics Corp Magnetic holding means in a surface plate dimensional measuring apparatus
US4310963A (en) * 1980-04-23 1982-01-19 Rudi Blumle Method for the fabrication of an apparatus for the close fitting positioning of workpieces to be machined
US5026033A (en) * 1989-11-22 1991-06-25 The Budd Company Universal system for the support and positioning of a workpiece
US5107599A (en) * 1990-08-28 1992-04-28 General Motors Corporation Universal fixture for coordinate measuring machines
US5505438A (en) * 1994-11-30 1996-04-09 Caterpillar Inc. Work piece locating apparatus

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