NL1041084B9 - A method and apparatus for quickly and accurately centering and clamping both cylindrical and conical objects such as gauges, smooth or threaded, internally and externally, for accurately measuring in particular outer diameters, core diameters and flank diameters using a known 2-dimensional scanning measuring machine. - Google Patents

Abstract

The invention relates to a method and apparatus based thereon for quickly and accurately centering and clamping cylindrical and conical objects such as nut gauges and bolt ring gauges for geometrically scanning the external or internal contours with the aid of a known 2-dimensional scanning measuring machine.

Description

Dutch Patent Application Number: 1041084

Title: a method and apparatus for quickly and accurately centering and clamping both cylindrical and conical objects such as gauges, smooth or threaded, internally and externally, for accurately measuring in particular outside diameters. core diameters and flank diameters using a known 2-dimensional scanning measuring machine.

The invention relates to a method and apparatus based thereon for quickly and accurately centering and clamping cylindrical and conical objects such as swivel gauges and bolt ring gauges for geometrically scanning the external or internal contours with the aid of a known 2-dimensional scanning measuring machine, (fig. 1)

The known clamping methods of the 2D-Scanners have the advantage over the single-axis measuring machines that there is no need to align without this having a negative influence on accuracy. For conical thread calibers with high pitch and conicity, however, these known clamping methods of the 2D Scanners were not optimal. This invention relates to an improvement of the known clamping methods for 2D-Scanners so that the same advantages and the same accuracy can also be achieved by internal and external conical thread calibers.

First it is explained how a measurement is carried out with a single-axis measuring machine and then the known clamping methods of the 2D Scanners.

Single-axis measuring machines are known for measuring internal and external diameters (Figs. 16 and 17).

The well-known single-axis measuring machine that is equipped for calibrating ring gauges consists of: 37) Adjustment ring 38) Ball-shaped measuring point on the left 39) Ball-shaped measuring point on the right 40) Movable measuring bracket on the left 41) Fixed measuring bracket on the right 42) lncremental measure with opto-electronic measuring head and display 43 ) Measuring pinole with straight guide 44) Machine frame 45) Kinematic swimming table with adjustable tilt and cross adjustment for aligning ring gauge 46) Fixed pinole

The known single-axis measuring machines have the disadvantage that both the adjustment caliber and subsequently the object to be measured have to be aligned very accurately for the optimum accuracy of the diameter measurement value. If the measuring axis 43 of the single-axis measuring machine does not intersect the center line of the rings 37 perpendicularly, the measurement is not accurate.

If an internal diameter is to be measured on a single-axis measuring machine, it is equipped with two measuring brackets 40 and 41 with two ball-shaped touch points 38 and 39. A certified setting ring 37 with an accurately calibrated and thus known diameter is then placed on the kinematic support table 45, after which this it must be tilted to make the center line of the setting ring cross perpendicular to the measuring axis 43 of the single-axis measuring machine. The measurement display shows the smallest value. The ring is then translated by means of the kinematic table so that the display of the single-axis measuring machine indicates the largest value.

These two processes must be repeated iteratively for the best accuracy. The diameter from the certificate of the calibrated adjustment ring is then entered in the readout display. National measuring institutions can give measurement uncertainties for setting rings in the order of 0.3 pm.

To now determine the unknown diameter of the ring to be measured, the adjusting ring is removed from the single-axis measuring machine and the ring to be measured is clamped, aligned and measured in the same way.

The measured value of the measured ring is then immediately presented on the display of the single-axis measuring machine. The difference in diameter between the certified setting ring and the measured ring is therefore assumed, and that both rings are precisely aligned, so that the measuring axis of the single-axis measuring machine intersects the center lines perpendicularly.

For measuring external diameters with a single-axis measuring machine, the brackets 40 and 41 are removed and replaced by two parallel touch points flat or with knife edges 48 and 49. (Fig. 17)

The well-known single-axis measuring machine that is equipped for calibrating pen gauges consists of: 47) Adjustment pen gauge 48) Knife side measuring point left 49) Knife side measuring point right 50) Movable measuring pinole left 51) Fixed measuring pinole right 52) Display 53) lncremente! electronic measuring head Machine frame 54) Measuring pin with straight guide 55) Machine Frame 56) Kinematic swimming table with adjustable tilt and cross adjustment for aligning pen gauge 57) Fixed pinole

For the setting of the single-axis measuring machine is now

A certified adjustment gauge 47 with a precisely calibrated and thus known diameter is then placed on the kinematic support table 56, after which it must be tipped to allow the center line of the adjustment to cross perpendicularly with the measuring axis 54 and 50 of the single-axis measuring machine.

Here, the measurement display 52 indicates the smallest value. This process must be repeated iteratively for the best accuracy. The diameter from the certificate of the calibrated adjustment pin 47 is then entered into the readout display 52. National measuring institutes can give measurement uncertainties for instinctne in the order of 0.2 to 0.3 pm.

To determine the unknown diameter of the pin to be measured, the certified set point is taken from the single-axis measuring machine and the pin to be measured is clamped, aligned and measured in the same way.

The measured value of the measured pin is then immediately presented on the display of the single-axis measuring machine. It is therefore assumed that the diameter difference between the certified pin and the measured pin is correct and that both pins are precisely aligned, so that the measuring axis of the single-axis measuring machine crosses the center lines perpendicularly.

Of course, the temperature of the equipment and the gauges must be constant and preferably as close as possible to the international measuring temperature of 20 ° C.

These are measurement uncertainties that are small in relation to the required tolerances and must therefore be in the order of parts of or a few micrometers.

The 2-dimensional scanning method and 2D scanners are described in, among other things, the patent papers of Ir.R. Galestien: EP0589500 METHOD FOR GAUGING AND SCANNING OR SCREW THREADS AND SIMILAR GROOVES, and NL1005718 METHOD FOR ACCURATE MEASUREMENT OF SCREW THREAD AND RELATED GEOMETRIES.

The known 2D scanner with caliber recording of this invention is shown in detail in figure 1 consisting of: 01: linear electronic displacement sensor FRONT for vertical Y-axis position 02: computer-controlled vertical axis drive 03: linear electronic displacement sensor BACK for vertical Y-position axis 04: axis of drive vertical axis 05: precision column for guidance vertical axis 06: precision line for guidance horizontal axis 07: linear electronic displacement sensor for position horizontal X-axis 08: system for setting measuring force for scanning top and bottom caliber 09: computer-controlled horizontal axis drive 10: spindle for horizontal axis drive 11: scan arm 12: cabinet plate left of housing 13: holder for accurate and reproducible mounting interchangeable caliber recordings 14: interchangeable caliber recording according to the present invention 15: double-sided scan probe 16: to be measured (calibrate ) conical thread gauge 17: electronic bag ter for measuring angular position φ of scan arm 18: push-button for fixing caliber against exchangeable caliber recording

The known 2D scanner with conical caliber (16) to be calibrated and the recording according to the present invention (14) is shown schematically in Figure 2 in the situation that the scan probe (15) scans the top of the caliber and in the situation that the bottom is scanned.

With the known 2D scanning technique, the profiles of a thread gauge are scanned at the top with the bottom point of the scan probe (15) and the bottom with the top point of the scan probe.

While the scanning point of (15) follows the contour of the profiles at the top and at the bottom, the electronic displacement sensors 01, 03, 07 and 17 are read simultaneously and very dynamically by the connected computer. Displacement sensor (03) is optional and is used to measure and compensate for yawing of the Y-axis displacement: compensation of the Abbe error.

Data processing creates a mathematical cross-section of the caliber with a plane through the center line of the caliber. The following can then be determined for each thread pass:

Outer diameter, core diameter, simple flank diameter, flank diameter, virtual flank diameter, pitch, partial flank angles, profile purity and conicity.

With conical gauges, all diameters depend on the location on the center line.

With the known 2D scanner, this location is determined with respect to the front side of the caliber which is pressed against the caliber receiving (14) by the push-button (18).

The scan probe (15) moves in a plane (20) that is determined by the straight guides of the X-axis (06), the Y-axis (05) and the rotation φ in the XY plane about hinge (19) (Figure 3) .

This plane is called scan plane.

In an ideal and thus theoretical situation, the center line of the caliber to be calibrated lies precisely in this scanning plane. However, this will not be the case in practice. Even at the smallest distance from the axis caliber (16) to scanning surface (20) this gives rise to measured values of the diameters that are too small. This is not permitted for accurate calibrations. With the known clamping method this problem is solved for parallel or smooth threaded calibers and for smooth conical pin and ring calibers, but the accuracy is not optimal for conical threaded ring and pin calibers with high pitch and steep conicity as with API Spec 7-2.

The starting point of the known centering method is that the scanning surface (20) of the machine does not have to coincide perfectly with the axis of the measuring object, while the measured value of the diameter of the measuring object is exactly the same as the diameter if the scanning surface (20) does would have coincided with the center line of the measurement object (16). (Fig. 6) It will be demonstrated that this known method is accurate for parallel cylindrical measurement objects but is not accurate for the measurement of conical threads with coarse pitch and steep conicity.

The disadvantage of the known centering method of the above-mentioned known 2D scanner is that the centering of conical thread calibers and conical thread products is not accurate, so that the accuracy of the diameter measurement with the 2D scanner is adversely affected.

The centering method according to the invention and the devices based on it eliminate this disadvantage for conical internal and external threads, while also parallel cylindrical internal and external objects can be optimally centered and clamped on a 2D surface with a thread and smooth conical internal or external objects. scanner.

On these aforementioned known measuring machines, the measuring objects such as bolt-ring gauges and smooth ring gauges are centered on the inner diameter and clamped on a support (fig. 5, 5a and 6). The supports are interchangeable for other types and fit accurately reproducibly in the U slot of the holder (13) that is stably fixed to the machine (12).

The plane of the support, against which the front end of the caliber is pressed, is perpendicular to scanning plane (20) with perpendicular tolerance in Figure 5.

There are supports for internal and external gauges of various sizes.

An important starting point of the known centering method is that the distance between the scanning surface (20) and the center line (23): the eccentricity need not be perfectly zero, but remains the same at the same relevant support for a certain diameter range of the bores. This is achieved by the construction of the supports and the known holder for the mount (13).

First, it will be explained how the known centering method functions for parallel cylindrical internal objects such as calibrators. bolt gauges and bores.

It is important for the measuring method of the above-mentioned known 2-dimensional scanning measuring machines that the axis (23) of the bore of the measuring object is oriented parallel to the scanning plane (20) in which the scanning probe (15) can move from the 2D -scanner. This is achieved by the two centering edges (21) of the support on which the inner diameter rests against. The already known support with the two centering edges (21) can be interchangeable, whereby it can be placed very reproducibly on the scanner, so that the eccentricity always has the same value even after repeated changing. These two centering edges (21) are accurately parallel to each other and parallel to the X-axis of the 2D scanner and are also mutually mirrored as well as possible symmetrically with respect to the scanning plane (20) in which the scan probe (15) can move.

The two centering edges (21) are robustly integrated with the support (24) and are perpendicular to the plane against which the end face of the caliber is pressed.

First, an adjustment ring gauge (22) with a precisely calibrated and thus accurately known diameter Djr-kai is clamped on the support (24).

The support (24) has 2 centering edges (21) on which the bore of the ring rests.

The distance between the center line (23) of the adjustment ring (22) and the scanning surface (20) is determined by this. This distance is called eccentricity.

The scan probe (15) is used to scan over a certain length at the top and bottom of the bore. The distance between the two points of scan probe (15) is determined in a different way.

The measured value of the Dint.meet ring diameter can be calculated with this.

This procedure is called intermediate calibration.

As a result, it becomes known how much the diameter Dint.meet is smaller than the real diameter Dir.ka !. This difference in diameter was created as a result of this eccentricity: the eccentricity correction EXinten cannot be neglected.

(formula 1)

Thereafter, on the same support, a ring gauge or a bolt washer gauge is measured that has a diameter Dint in the same order of magnitude as Djr. | <Ai of the setting ring (22). Figure 7.

Due to this construction of the support (24) and the 2 centering edges (21), the distance between the center line of this caliber to be measured and the scanning surface (20) is the same as during the intermediate calibration.

Because the support is constructed in such a way that the eccentricity is the same for both the intermediate calibration and the measurement, the measured value of the Dint-diameter diameter of the ring gauge or a bolt washer gauge is measured as much too small as the adjustment ring and can therefore be corrected by: add the eccentricity correction EXint:

(formula 2)

Without having to measure exactly over the heart (23) of the bores, the measurement result of the diameter is as accurate as if it was measured over the heart.

This method is valid for both parallel cylindrical threads and for smooth rings.

Simply put: 1) The center of the certified setting caliber is next to the scanning plane; 2) The diameter of the certified setting gauge is therefore too small; 3) Because the certified diameter is accurately known, it is also known how much the diameter is measured too small: the diameter correction; 4) This value is stored in the computer's memory; 5) The center of the caliber to be measured, with a diameter in the same order of magnitude as the certified setting caliber, is the same as the setting caliber next to the scanning plane; 6) This diameter is therefore also measured too small; 7) The computer adds the diameter correction to the measured value and presents the corrected diameter; 8) The maximum diameter difference between the diameters of the certified setting caliber and the caliber to be measured is calculated in such a way that the influence is negligible until the measurement uncertainty of the measurement.

However, for conical internal threads this is not the case as will be shown below.

Next, it is explained how the known centering method functions for parallel cylindrical external objects such as smooth pin calibers. jibs and shafts.

On these aforementioned known measuring machines, the measuring objects such as parallel cylindrical nut calibers and smooth shafts are centered and clamped on the outer diameter. (Fig. 8) It is important for the measuring method of the aforementioned known 2D scanners that the center line and thus the center plane ( 25) of the measurement object (27) is oriented in parallel with respect to the scanning plane (20) in which the scan probe (15) can move. This is achieved by the two centering surfaces (28) of the support on which the outer diameter rests against. The support with the two centering surfaces can be interchangeable, whereby it can be placed on the 2D scanner in a very reproducible manner.

These two centering surfaces (28) together form a V, the bisector surface (25) of which is parallel to the scanning surface (20) in which the scanning probe can move and coincide as well as possible with it.

The center line of the measurement object also lies in the bisector line (25).

The two centering surfaces (28) are robustly integrated perpendicularly with the support (26).

The face of the support (26) against which the end face of the gauges are pressed is perpendicular to the scanning face (20) of the 2D scanner.

As with internal measurements, an intermediate calibration is first performed. Prior to the measurement of the external measuring object, an adjustment calibrator with an accurately calibrated diameter Dpk.kai is first centered on the above-mentioned V-support and then clamped and then measured, whereby the center line of the adjustment calibrator (27) is oriented parallel to the scanning plane. (20) in which the scan probe (15) can move. The outer diameter of the adjustment gauge measured over the center point is therefore well known. (Fig. 8) Because the scanning plane (20) of the scan probe does not exactly coincide with the center line of the set-up gauge and is parallel to the center line, the measured value of the diameter of the set-up gauge Dpk measurement will be smaller than the diameter Dpk-kai · Because the external diameter of the adjustment gauge is measured next to the center point and not through the center point, (fig.9)

The difference between the measured diameter Dpk.meet and the actual calibrated diameter Dpk.kai of the calibrated adjustment pin is determined by the eccentric deviation: the distance between the center line of the adjustment pin (27) and the scanning plane (20) of the measuring machine and can are indicated by eccentricity correction Ex.

(formula 3)

The value of EXext is stored in the computer of the scanner.

After this, the measurement object is centered on the same support mentioned above, clamped and externally scanned. The distance between the center line of the measuring object and the scanning surface of the scanning measuring machine is therefore the same as the previous distance between the center line of the adjustment gauge and the scanning surface of the measuring machine.

If the outer diameter of the object does not deviate too much from the diameter Dpk-kai of the above-mentioned adjustment gauge, the eccentricity correction EXext is in this case virtually the same.

If the outer diameter of the object deviates much from the diameter DPk-kai of the above-mentioned adjustment gauge, the eccentricity correction EXext can in this case be corrected with simple trigonometry.

The measuring machine measures the external diameter of the measuring object D ext-meet The external diameter of the measuring object corrected for the eccentric deviation is then

(formula 4)

The diameter measurements of the internal and external objects described above are based on the fact that the adjustment caliber and the object have the same eccentric location with respect to the scanning plane of the probe of the 2D scanner.

However, for external conical threads this is not the case as will be shown below.

THE MEASUREMENT OF A CONICAL MORP CALIBER

In the case that the objects are conical nut calibers or conical bolt ring calibers, then the eccentricity is no longer constant but also depends on the conicity and the pitch of the screw thread. Formulas 1,2, 3 and 4 are then no longer valid. The accuracy of the conical screw gauges is therefore adversely affected.

This will be demonstrated for the combination of a conical bore gauge (13) and a V-support according to figures 8 and 9. (fig.10)

After a parallel cylindrical pin gauge has been measured on the above-mentioned support with the two V-faces (28) as an intermediate calibration, the conical nut gauge (30) is clamped and measured.

Figure 10 shows diagrammatically a single-bore conical caliber with conicity T (mm / mm) and pitch p. Of the external caliber, only the helix of the profile top is drawn. Only the profile top makes contact with the centering surfaces (28).

The caliber is imposed on the aforementioned V-level support.

The angle between the two planes (28) is β.

For the measurement of conical calibres on the 2D scanner, the end face (31) is the reference for the axial location of the plane in which the outer diameter, core diameter and flank diameter must be determined (32) (gauge plane). The end face of conical caliber calibers is therefore precisely machined flat by the manufacturer and perpendicular to the axis of the caliber. The end face of the conical caliber gauge (31) must be pressed against the support (26) for this. As a result, the center line of the caliber is oriented parallel to the X-axis axis of the 2D scanner so that there is no longer an air gap. The distance between the gauge plane (32) of the caliber related and the reference plane (31) is now known.

The caliber must then be pushed into the V of the two faces while the end face (31) remains pressed against the back plate. The helix of the profile tips now touches points A and B on the two V-faces (9) with resp. radius R1 and R2.

The angle z_AQB between the heart and the points of contact A and B is α = 180 ° - β

The distance in the axial direction between A and B is: AX = p α / 360

Due to the conicity T (mm / mm), the length difference AR between R1 and R2 is:

In the case of a parallel caliber, the center line in the bisector is flat (25), while in the case of a conical caliber the heart ΔΕΧ is located next to the bisector.

The distance ΔΕΧ between the heart Q of the caliber and the bisector-plane (25) of the two V-planes, in which the center of the calibrating gauge has also been located, is then: ΔΕΧ = AK - BL Where: AK = R1 sin ( a / 2) BL = R2 sin (a / 2) ΔΕΧ = (R1 -R2) · sin (a / 2) = ΑΧ · T / 2 · sin (a / 2) = ΔΕΧ = p (180 ° - β) T sin ((180 ° - β) / 2) 1720

The eccentricity of the conical caliber is therefore also determined by: 1) The pitch p

2) The conicity T 3) The angles of the V-planes (28)

Because the eccentricity EXext of the center point of the adjustment gauge and the scanning plane (20) in which the probe (15) of the 2D scanner moves differs from the eccentricity EXext + ΔΕΧ between the center point Q of the conical moped gauge and the scanning plane (20) in which the probe of the 2D scanner moves, the diameter in the gauge plane (32) is measured inaccurately.

The point on the outer diameter at which the conical bore gauge on the left centering surface (28) has a different axial position than the support point on the right centering surface (28) of support (26).

In connection with the conicity of the conical caliber, the caliber diameter of the left support is different from the caliber diameter of the right support. As a result, the center line of the conical thread caliber does not lie in the same plane in which the adjustment caliber lies during the intermediate calibration. EXext from formula 4 is therefore no longer valid.

Formula 4 will therefore give inaccurate measured values for the outer diameter, core diameter and flank diameter of the conical thread gauge.

THE MEASUREMENT OF A CONICAL BOUTRING CALIBER

It is clear that the same problem arises for the measurement of conical bolt ring gauges. The point on the core on which the conical bolt ring gauge rests on the left center side (21) has a different axial position than the support point on the right center side (21) of support (24).

In connection with the conicity of the caliber, the caliber diameter of the left support is different from the caliber diameter of the right support.

As a result, the center line of the conical thread caliber does not lie in the same plane in which the adjustment caliber lies during the intermediate calibration. EXjnt from formula 2 is therefore no longer valid.

Formula 2 will therefore give inaccurate measured values for the outer diameter, core diameter and flank diameter.

The use of 2 V faces (28) for external conical threads and 2 centering edges (21) for internal conical threads is therefore not sufficient.

The use of the known support constructions is therefore not well possible for measuring conical internal and external threads.

Simply put: 1) The center of the certified setting caliber is next to the scanning plane; 2) The diameter of the certified setting gauge is therefore too small; 3) Because the certified diameter is accurately known, it is also known how much the diameter is measured too small: the diameter correction; 4) This value is stored in the computer's memory; 5) The center of the conical thread gauge to be measured, with a diameter of the same order of magnitude as the certified adjustment gauge, is not at the same distance as the adjustment gauge next to the scanning plane: the eccentricity is different in both cases; 6) The two points of contact between the thread gauge and the support are at two different points of a thread; 7) Due to the conicity, these two contact points each have a different radial distance to the center line of the caliber; 8) So the eccentric location of the conical thread gauge to be measured is different from that of the certified adjustment gauge; 9) The application of the excntrity correction is therefore less accurate for the flank diameter, outside diameter and the core diameter.

THE SOLUTION

The centering method according to the present invention and the resulting support structures eliminate these disadvantages mentioned above.

The point of departure for a correct eccentricity correction is that the eccentricity of the certified smooth adjustment caliber for the intermediate calibration must be equal to the eccentricity of the conical thread to be measured both internally and externally. The eccentricity of the conical thread may no longer be influenced by: 1) The pitch p

2) The conicity T

The solution to these above requirements consists of 2 support cones (33) that are nominally symmetrically positioned with respect to the scanning surface (20) on support (31) and whose conicity is equal to the normalized conicity T of the conical thread to be measured, ( 11, 12, 13 and 14)

The 2 cones meet the following criteria: 1) Conicity is equal to the normalized conicity T of the measuring conical thread; 2) The 2 cones (33) are mirror symmetrically oriented, the mirror surface (23) of which is parallel to the scanning surface (20) in which the probe (15) moves; 3) The center lines of the two cones are perpendicular to the pressure plate of the support (31 whereby the center line of the conical caliber is oriented parallel to the X-axis of the machine; 4) The end face of the caliber to be measured, being the reference plane for the axial position of the caliber in which the outer diameter, core diameter and flank diameter are defined, lies completely against the pressure plate of the support so that the diameters can be calculated at this axial position by a known method; 5) Since various thread conicities have been standardized worldwide, such as API Spec 7-2, a few cones per caliber type are required; 6) The cones may be truncated; 7) The cones have a concentric parallel cylindrical section (35) for the purpose of being able to correctly center an adjustment caliber for the purpose of intermediate calibration, (Figure 14)

In addition, the eccentricity of the calibrated adjustment pin (27) must be equal to the eccentricity of the conical bore gauge (30). (fig.14)

This is achieved by making the part of the 2 support cones (33) that is mounted against the support (31) concentrically parallel and cylindrical (35).

The axis of the parallel cylinder section (35) is accurately concentric with the axis of the cone (33).

Figure 15 shows the same combination of calibrated adjustment ring (22) and internal conical thread (36).

The application of 2 identical support elements each consisting of a truncated cone with specific conicity and a concentric parallel cylinder now make it possible to both optimally center and measure on the 2D scanner: 1) External conical thread; 2) Internal conical thread; 3) Smooth conical pins; 4) Smooth conical rings; 5) External parallel thread; 6) Internal parallel thread; 7) Smooth parallel cylindrical pins; 8) Smooth parallel cylindrical rings.

Claims (7)

Method for clamping measuring objects such as gauges on a known 2D scanner for accurately measuring the outer diameter, flank diameter and core diameter of: external conical thread, internal conical thread, smooth conical pins, smooth conical rings, external parallel thread, internal parallel thread, smooth parallel cylindrical pins, smooth parallel cylindrical rings characterized in that the 2D scanner is provided with an interchangeable support formed by a pressure plate with two perpendicular or non-exchangeable identical support elements perpendicular to each other consisting of a truncated cone and a concentric parallel cylinder on which these two supporting elements are first centered and scanned a precisely certified cylindrical adjustment caliber and then the caliber to be measured is centered and scanned while the eccentricity, the distance between the plane in which the scan probe moves and the the center of the certified setting caliber on the one hand and then the eccentricity of the caliber to be measured on the other are exactly the same. A method according to claim 1, characterized in that the mirror symmetry plane of the 2 identical supporting elements is parallel to the above-mentioned plane in which the scan probe moves while the distance between these two planes is adjusted as small as possible. A method according to the preceding claims wherein the center line of each support element is parallel to the X axis of the measuring machine. A method according to the above claims, characterized in that the conicity of the two identical support cones is equal to the normalized conicity of the caliber to be measured so that the center line of the caliber to be measured is tensioned parallel to the X axis of the machine while the end face of this caliber, being the reference plane for the axial position of the caliber in which the outer diameter, core diameter and flank diameter are defined, abuts completely against the pressure plate of the support. 5. On the basis of the standardized conical threaded calibers to be measured, the two supporting elements according to the above claims are dimensioned such that the length of the cones is so long that correct centering and accurate scanning are guaranteed because both cones are in contact with at least 1 point of the helix line of the profile tips of the conical thread gauge. A support according to the above claims, characterized in that the two identical support elements are interchangeable, as a result of which the truncated cones have a conicity that is equal to the normalized conicity of the conical thread calibers to be measured as in accordance with the API Spec 7-2 standard. A support according to the above claims, characterized in that the diameters of the cylindrical and conical sections of the 2 identical support elements and the mutual center-to-center distance are adjusted to the diameter of the object to be measured.