JP2007206086A - Circularity measuring device and cylindrical grinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rapidly and precisely implement circularity manufacturing of an eccentric cylinder. <P>SOLUTION: The figure representing schematically motion of an instrument sliding means on a cross-sectional plane of a crank pin (an eccentric cylinder) shows a way of parametric transformation transforming a function y (ψ, x) to a function y (θ). Since an output value y, a measure variable, of a three-point contact type instrument, a rotation angle ψ around a C-axis at the center O of a crank pin, and a distance x between the C-axis and W-axis are all measured simultaneously, a function f: θ=f (ψ, x) is determined and, therefore, an output value y (the function value of y (ψ, x)) can be treated as the function y (θ). In other words, by measuring measure variables y, x, and ψ simultaneously, the function y (θ) of θ as an independent variable is found, without outside unload of work held rotatably with a rotating shaft. Moreover, the determination of a cylindrical radius r (θ) and an X-axis correcting amount δx (ψ) is also automatable simultaneously. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a roundness measuring device for measuring the roundness of an eccentric cylinder integral with a workpiece rotatably supported by a rotating shaft, and a cylindrical grinder for rounding the cylinder, in particular. The present invention relates to a cylindrical grinding machine that performs roundness measurement and circular processing of an eccentric cylinder (eg, a crankpin) while rotatably supporting a workpiece.

In grinding processing of crankpins and cams on the crankshaft of a gasoline engine, the rotational motion around the workpiece rotation axis (hereinafter sometimes referred to as “C-axis”) and the C-axis of the grinding wheel platform are perpendicular to each other. Grinding is performed by properly synchronizing the parallel movement in the X-axis direction.
In these conventional technologies, improvement in tracking accuracy, synchronization accuracy, or motion accuracy is seen due to advancement of technologies such as servo control devices and numerical control devices.

  However, it is currently impossible to sufficiently cope with shape errors due to changes in the rigidity of the workpiece and grinding resistance, etc., simply by improving these precisions. For this reason, when high grinding accuracy is required. During the grinding process, once the workpiece is removed from the grinding machine, the shape of the workpiece (roundness of the crankpin, cam shape, etc.) is accurately measured again, and the movement of the C axis or X axis Grinding is performed again after obtaining the correction amount.

  In the field of measurement technology, as a method for accurately measuring the roundness of a cylindrical workpiece, for example, “Journal of the Japan Society of Mechanical Engineers, Vol. 53, No. 376, Technical Paper“ Measurement of Roundness of a Cylindrical Workpiece ” A method using a three-point contact method described in “Method” (May 1950) is generally known. In this technical paper, a theoretical analysis is performed when measuring the roundness of a cylindrical workpiece using a three-point contact type (V-block type, horseback gauge type, tripod gauge type) measuring instrument. In the case of the equation, as shown in the following equations (1) to (6) and FIGS. 14, 15, and 16, a method for quantitatively obtaining the roundness error of the cylindrical workpiece is shown. Yes.

However, the definitions of each variable, symbol, function, etc. are as follows.
(Graphic symbol)
K: Cylindrical workpiece such as a crank pin (cross-sectional circumference)
O: Origin (any one point near the center of K: fixed point on workpiece cross section)
C: Any fixed point on the workpiece cross-section plane defining a primitive OC M: radius a _m becomes the standard dimensions gauge cylinder (cross section circumference)
a: Contact point between the end face of the measuring element of the three-point contact type (horse riding gauge type) measuring device and K b: Contact point between the contact surface of the horse riding gauge and K c: Contact point between the contact surface of the horse riding gauge and K d: Horse riding Gauge reference point (center point of included angle α)
a ′: vertical foot dropped from the origin O to the end face of the measuring element of the measuring instrument b ′: vertical foot dropped from the origin O to the contact surface of the riding gauge c ′: lowered from the origin O to the contact surface of the riding gauge Vertical foot (variable)
θ: Angle from original line OC α: Angle between horse riding gauges n: Natural number (Fourier series expansion index)

(constant)
a ₀ : Average radius of K c _n : Expansion coefficient of each term at the time of Fourier series expansion of r (θ)
(Determined by harmonic analysis)
φ _n : Initial phase of each term in Fourier series expansion of r (θ)
(Determined by harmonic analysis)
a _m: radius m _y gauge cylinder M: mean value of y (θ) J: upper limit value of n (practically a sufficient above technical papers at about 50.
Considering up to J = 12. )
N: Number of times of measurement when measuring y (θ) (number of measurement point samples).
(function)
r (θ): Radius of K with θ as an independent variable y (θ): Output value of a three-point contact measuring instrument with θ as an independent variable μ (α, n): Each spectral component appearing in y (θ) Expansion rate

(Equation 1)
_{r (θ) = a 0 +} n = 1 Σ J c n cos (nθ + φ n) ... (1)
(Equation 2)
a _m {1 / sin (α / 2) -1} -y (θ)
= {R (θ + π / 2−α / 2) + r (θ−π / 2 + α / 2)}
/ {2sin (α / 2)}-r (θ) (2)
(Equation 3)
y (θ) = (a ₀ −a _m ) · {1-1 / sin (α / 2)}
+ _{N = 2} Σ ^J {μ (α, n) c _n cos (nθ + φ _n )} (3)
(Equation 4)
μ (α, n) = 1− {cos n (π / 2−α / 2)} / sin (α / 2) (4)
(Equation 5)
_{m y = ∫y (θ) dθ} / 2π ( integral range: 0 ≦ θ ≦ 2π)
= (A ₀ −a _m ) · {1-1 / sin (α / 2)}
^{_{= (I = 0 Σ N-}} 1 y i) / N ... (5)
(Equation 6)
_{a 0 = a m + m y} / {1-1 / sin (α / 2)} ... (6)

That is, if y (θ) is measured using an appropriate α or an appropriate combination of α in the three-point contact method, c _n and φ _n can be calculated for all n. It can be seen from the above technical paper that the error can be obtained quantitatively as “δr = r (θ) −a _m ”. However, in this case, the gauge cylinder M of radius a _m becomes the standard dimensions as desired cylindrical shape.
The definition of each variable, symbol, function, etc. is the same in the following.

The above prior art has the following problems and is expected to be improved overall. (Problem 1) During grinding, once the workpiece is removed from the machine, and the workpiece shape (circularity of the cylinder, etc.) is measured accurately, the work is performed between the grinding machine and the measuring machine. There may be a deviation in the set position of the reference point with respect to the object. Therefore, in many cases, sufficient measurement accuracy cannot be ensured due to this error.
(Problem 2) Setting the reference point requires a long adjustment time, and this operation is difficult to automate. For this reason, productivity, such as cylindrical grinding, does not improve.
(Problem 3) When the roundness of an eccentric cylinder such as a crankpin is scanned using a three-point contact measuring instrument etc. while the workpiece is rotatably supported, the measuring instrument is connected to the cylinder circle by a link mechanism or the like. It must be moved along the circumference. However, since the link mechanism has many degrees of freedom, and the measurement system also has degrees of freedom such as the C-axis and the X-axis, the phase measured from the center of the cylinder when measuring the roundness (y (θ)) is used. It is not easy to accurately measure the angle (the aforementioned angle θ) at the same time.

  Further, for example, when manufacturing a crankshaft of an engine having a plurality of cylinders (cylinders), if the position (eccentricity and phase) of each crankpin with respect to the crank journal cannot be accurately worked, The ignition phase and the like cannot be accurately realized for each cylinder. For this reason, unless a positioning device that measures the position of the eccentric cylinder shaft at high speed and with high accuracy is developed, it is difficult to efficiently mass-produce high-performance engines with sufficiently suppressed fuel consumption, vibration, noise, etc. is there.

  Further, obtaining the position of the shaft of the eccentric cylinder very accurately is sufficiently useful for accurately measuring the roundness of the eccentric cylinder, and is a means for measuring the position of the shaft of the eccentric cylinder with high accuracy and high speed. Development is expected.

  The present invention has been made to solve the above-described problems, and the object thereof is high-precision circular machining of an eccentric cylinder integrated with a workpiece rotatably supported by a rotating shaft, and It is to provide means for realizing at high speed.

  A further object of the present invention is to provide means for carrying out processing of an eccentric cylinder at a high speed whose position of the center axis is extremely accurate with respect to the above-mentioned rotation axis.

In order to solve the above problems, the following means are effective.
That is, the first invention is a perfect circle for measuring the roundness of a cylinder eccentric from the rotation axis in a state where a workpiece having a cylinder rotating eccentric from the rotation axis is attached to a grinding machine in a grindable state. In the degree measuring device, the first pivot pivotably provided on the grindstone table, the first arm supported pivotally on the first pivot at one end, and the other end of the first arm. A second pivot that is movably provided, a second arm upper arm that is rotatably supported at one end by a second pivot, a second arm lower arm provided on the second arm upper arm, A roundness characterized by having a three-point contact measuring instrument that is provided on a two-arm lower arm and slides on the outer peripheral surface in contact with the outer peripheral surface of the cylinder and that measures the radius of the cylinder by a three-point contact method It is a measuring device.

  The second invention is a roundness measurement for measuring a roundness of a cylinder eccentric from the rotation axis in a state where a workpiece having a cylinder rotating eccentrically from the rotation axis is attached to a grinding machine in a grindable state. In the apparatus, with a measuring instrument for measuring the diameter of the cylinder in contact with the outer peripheral surface of the cylinder, and in a state where the measuring instrument is in contact with the outer peripheral surface of the cylinder along the rotation trajectory around the rotation axis of the cylinder A measuring instrument sliding means for moving; a detecting means for rotating the rotating shaft to detect an output value of the measuring instrument at a constant time period; and a roundness calculating means for calculating the roundness of the cylinder from the output value. It is a roundness measuring apparatus characterized by having.

  A third invention is a roundness measurement for measuring a roundness of a cylinder eccentric from the rotation axis in a state where a workpiece having a cylinder rotating eccentrically from the rotation axis is attached to a grinder so as to be ground. In the apparatus, with a measuring instrument for measuring the diameter of the cylinder in contact with the outer peripheral surface of the cylinder, and in a state where the measuring instrument is in contact with the outer peripheral surface of the cylinder along the rotation trajectory around the rotation axis of the cylinder Measuring device sliding means to be moved, detecting means for rotating the rotating shaft and detecting the output value of the measuring device at every fixed rotation angle of the rotating shaft, and roundness for calculating the roundness of the cylinder from the output value A roundness measuring apparatus comprising a calculating means.

  The fourth invention is characterized in that in the second or third invention, there is provided an average radius calculating means for calculating an average radius of the cylinder from the average value of the output values.

  Further, the fifth invention is characterized in that in the second or third invention, there is provided a radius distribution calculating means for obtaining a Fourier coefficient of an output value and obtaining a radius distribution related to a rotation angle of a radius of the cylinder from the Fourier coefficient. To do.

  In a sixth aspect based on the second or third aspect, a Fourier coefficient of an output value is obtained, a radial distribution relating to a rotation angle of the radius of the cylinder is obtained from the Fourier coefficient, and a difference between the radial distribution and a reference radius is obtained. And a true circle error distribution calculating means for obtaining a true circle error distribution relating to the rotation angle of the true circle error.

A seventh invention is characterized in that, in the fifth invention, there is provided feed amount correcting means for correcting the feed amount distribution of the grindstone related to the rotation angle of the rotating shaft based on the radius distribution obtained by the radius distribution calculating means. To do.
According to an eighth invention, in the sixth invention, there is provided a feed amount correcting means for correcting the feed amount distribution of the grindstone related to the rotation angle of the rotating shaft based on the perfect circle error distribution obtained by the true circle error distribution calculating means. It is characterized by that.

  A ninth aspect of the invention is a roundness measurement for measuring a roundness of a cylinder eccentric from the rotation axis in a state where a workpiece having a cylinder rotating eccentrically from the rotation axis is attached to a grinding machine in a grindable state. In the apparatus, with a measuring instrument for measuring the diameter of the cylinder in contact with the outer peripheral surface of the cylinder, and in a state where the measuring instrument is in contact with the outer peripheral surface of the cylinder along the rotation trajectory around the rotation axis of the cylinder The measuring instrument sliding means to be moved, the rotating means to rotate, the detecting means to detect the output value of the measuring instrument, the Fourier coefficient of the output value detected by the detecting means is obtained, and the rotation angle of the radius of the cylinder from the Fourier coefficient A radius distribution calculating means for obtaining a radius distribution with respect to the rotation angle, and a feed amount correcting means for correcting the feed amount distribution of the grindstone related to the rotation angle of the rotating shaft based on the radius distribution obtained by the radius distribution calculating means. Roundness measurement It is the location.

  A tenth aspect of the present invention is a roundness measurement for measuring the roundness of a cylinder eccentric from the rotation axis in a state where a workpiece having a cylinder rotating eccentrically from the rotation axis is attached to a grinding machine in a grindable state. In the apparatus, with a measuring instrument for measuring the diameter of the cylinder in contact with the outer peripheral surface of the cylinder, and in a state where the measuring instrument is in contact with the outer peripheral surface of the cylinder along the rotation trajectory around the rotation axis of the cylinder The measuring instrument sliding means to be moved, the rotating means to rotate, the detecting means to detect the output value of the measuring instrument, the Fourier coefficient of the output value detected by the detecting means is obtained, and the rotation angle of the radius of the cylinder from the Fourier coefficient A true circle error distribution calculating means for calculating a true circle error distribution related to the rotation angle of the true circle error from a difference between the radius distribution and the reference radius, and a true circle error obtained by the true circle error distribution calculating means. Based on the distribution, A roundness measuring apparatus characterized by having a feed amount correction means for correcting the feed amount distribution of the grinding wheel about the rotation angle.

  An eleventh aspect of the invention is the three-point contact type measuring instrument according to any one of the second to tenth aspects, wherein the measuring instrument is in contact with the outer peripheral surface of the cylinder and measures the radius of the cylinder by a three-point contact method. It is characterized by that.

  A twelfth invention is the three-point contact measuring device according to any one of the fifth to tenth inventions, wherein the measuring device is in contact with the outer peripheral surface of the cylinder and measures the radius of the cylinder by a three-point contact method. The radius distribution is characterized in that the Fourier coefficient is corrected with an enlargement factor by a three-point contact type measuring instrument and is a radius distribution related to the rotation angle of the radius of the cylinder obtained from the corrected Fourier coefficient.

  In a thirteenth aspect based on the first aspect, the rotating shaft is rotated to detect the output value of the three-point contact measuring instrument at a constant time period, and the roundness of the cylinder is calculated from the output value. And a roundness calculating means.

  In a fourteenth aspect based on the first aspect, detection means for detecting the output value of the three-point contact measuring instrument at every fixed rotation angle of the rotation shaft, and the true value of the cylinder from the output value. And a roundness calculating means for calculating the circularity.

  A fifteenth invention is characterized in that, in the thirteenth or fourteenth invention, there is provided an average radius calculating means for calculating the average radius of the cylinder from the average value of the output values.

A sixteenth invention is characterized in that, in the thirteenth or fourteenth invention, there is provided a radius distribution calculating means for obtaining a Fourier coefficient of an output value and obtaining a radius distribution related to a rotation angle of a radius of the cylinder from the Fourier coefficient.
According to a seventeenth aspect, in the thirteenth or fourteenth aspect, a Fourier coefficient of an output value is obtained, a radius distribution relating to a rotation angle of the radius of the cylinder is obtained from the Fourier coefficient, and a true value is calculated from a difference between the radius distribution and a reference radius. It has a perfect circle error distribution calculating means for obtaining a true circle error distribution related to the rotation angle of the circle error.

An eighteenth aspect of the invention is characterized in that in the sixteenth aspect of the invention, there is provided feed amount correction means for correcting the feed amount distribution of the grindstone related to the rotation angle of the rotating shaft based on the radius distribution obtained by the radius distribution calculation means. To do.
According to a nineteenth aspect, in the seventeenth aspect, there is provided a feed amount correcting means for correcting the feed amount distribution of the grindstone related to the rotation angle of the rotating shaft based on the perfect circle error distribution obtained by the true circle error distribution calculating means. It is characterized by that.

In a twentieth invention according to any one of the sixteenth to nineteenth inventions, the radial distribution is obtained by correcting a Fourier coefficient with an enlargement ratio by a three-point contact measuring instrument, and obtaining a cylinder obtained from the corrected Fourier coefficient. It is a radius distribution with respect to the rotation angle of the radius.
A twenty-first invention is a cylindrical grinder having the roundness measuring device according to any one of the first to twentieth inventions.

The rotating shaft in each of the above means may be a rotating shaft.
The above-described problems can be solved by the above means.

According to the means of the present invention, when measuring the roundness of an eccentric cylinder integrated with a workpiece, the workpiece supported rotatably on the rotary shaft by a machine tool such as a grinding machine is removed outside the machine. The roundness of the eccentric cylinder can be measured as it is. For this reason, it is not necessary to remove the workpiece from the machine tool when measuring the roundness. Accordingly, the removal and attachment operations are eliminated, and at the same time, there is no deviation regarding the set position of the workpiece between the grinding process and the roundness measurement. As a result, it is possible to realize perfect circle processing with high accuracy and in a short time.

  Needless to say, the above-mentioned operation and effect can be obtained even if the rotation shaft is a rotation shaft.

  In addition, if a motion sensor that detects a motion parameter ξ related to the mechanical motion of the measuring device sliding means is used, it is possible to know (measure) the center coordinates (cylinder shaft position) of an eccentric cylinder such as a crankpin more accurately. it can.

  Furthermore, by combining such means with the above-mentioned means, it is possible to carry out more accurate roundness measurement and roundness processing without removing the workpiece from the machine.

Hereinafter, the present invention will be described based on specific examples.
However, the present invention is not construed as being limited to the following examples.

  FIG. 1 is a side view showing an overview of a cylindrical grinding machine 100 of the present embodiment. The disc-shaped grindstone 7 provided on the grindstone base 9 can be supported and rotated by the rotation axis W (point W in the figure). K represents the transverse cross-sectional circumference of the crankpin, and the center point O of this circumference K is the C-axis (point C in the figure) of the cylindrical grinding machine 100 by a support portion (not shown) of the cylindrical grinding machine 100. ) Around the circular orbit S. The distance x between the C axis and the W axis is controlled by the NC servo mechanism of the cylindrical grinding machine 100.

  Reference numeral 27 denotes a measuring element of a three-point contact type (horse riding gauge type) measuring device. The horse riding gauge 25 of the three-point contact type measuring instrument is supported by the second arm lower arm 22 so as to be slidable along the circumference K while being in contact with the outer peripheral surface of the crankpin (eccentric cylinder). The first pivot P is fixed to the grindstone base 9, and the measuring instrument sliding means is constituted by the first pivot P, the first arm 1, the second pivot P ', the second arm upper arm 21, the second arm lower arm 22, and the like. Has been. As a result, the three-point contact type measuring instrument can be smoothly contacted and moved along the circumference (side surface outer circumference) of the crankpin. Reference numeral 8 denotes a measurement value output line of a three-point contact type measuring instrument.

FIG. 2 shows the operation of the variable conversion means of this embodiment for converting the function y (ψ, x) into the function y (θ). This figure schematically represents the operation of the measuring instrument sliding means (FIG. 1) on the plane of the crank pin cross section. Here, θ is an angle around the point O (center of the crankpin), and an angle from the original line OC to the centerline (FIG. 3) of the three-point contact measuring instrument (circumference of the crankpin) It represents the angle coordinates of the upper measurement point p). Further, y, ψ, and x are measurement variables shown below.
(Measurement variable)
y: Output value of the three-point contact measuring instrument x: Distance between the C-axis and the W-axis (records the y-measurement value)
ψ: Rotation angle ク ラ ン ク WCO around the C axis of the crank pin (records the value at the time of y measurement)

Such variable conversion is realized by obtaining a function f of “θ = f (ψ, x, Λ)”. That is, if such a function f is obtained, the output value y (function value y (ψ, x)) of the three-point contact measuring instrument can be handled as a function value y (θ) with θ as an independent variable. It becomes. Here, Λ is an appropriate set (sliding mechanism parameter group) of various constants representing the structure related to the posture of the measuring instrument sliding means. Since these are constants, “Λ” may be omitted below.
A method for specifically determining such a function f will be described below.

  In addition to the above symbols, the following symbols (constants) are used in the description of FIG. As described in detail later, the above function f uses various constants (constants such as the length and angle of each part of the measuring instrument sliding means and machine tool) representing the structure related to the posture of the measuring instrument sliding means. Can be sought. That is, the set Λ in the present embodiment has the following seven constants as its elements.

(Sliding mechanism parameter group)
D: Deviation in the horizontal direction (X-axis direction) from the W-axis of the first pivot P
(C axis side is negative)
H: Height of the first pivot P from the W axis R: Radius of the circular orbit S L ₁ : Length of the first arm 1 L ₂₁ : Length of the second arm upper arm 21 L ₂₂ : Second arm lower arm 22 Length ζ: angle between the second arm upper arm 21 and the second arm lower arm 22

FIG. 3 shows the positional relationship between the two when the V gauge 25 is mounted on a cylinder having a perfect circular cross section with a radius a ₀ . In this figure, the point G is the center of a perfect circle with a radius a ₀ , and when such a theoretical perfect circle comes into contact with the contact surfaces A and B of the V gauge 25 perpendicularly, the center point of the true circle A distance L between two points G and the reference point d of the V gauge 25 is given by the following equation (7).
(Equation 7)
L≡Gd = a ₀ / sin (α / 2) (7)
In this way, the point G becomes a fixed point with respect to the point d and the contact surfaces A and B when the radius a ₀ is constant.

  On the other hand, since the cross-sectional circumference K of the crankpin having each actual measurement point p as an element is not actually a perfect circle, the center point O is not uniquely determined. That is, the origin O fixed on the cross section of the crankpin is strictly one fixed point determined so that “OC = R, ∠WCO = ψ” with respect to the point C near the center of K. In general, point G and point O do not match. Further, the distance OG between the two points varies depending on the angle θ. That is, this distance can be considered as a function OG (θ) of the angle θ.

However, when the following equation (8) holds, as long as the function f is obtained, the following equation (9) can be used.
(Equation 8)
OG (∀θ) << MIN (L ₂ , L ₂₁ , L ₂₂ + L) (8)
(Equation 9)
Od≈L (9)
That is, normally, as long as the function f is determined, even if the point O and the point G are identified, the error in the result is sufficiently small. This is because L ₂ , L ₂₁ and L ₂₂ are actually on the order of 10 cm to 1 m, whereas OG is 1 μm in length.

Therefore, as can be seen from FIG. 2, the function f can be specifically determined by using the following equations (10) to (22) by equating the point O and the point G.
(Equation 10)
L ₂ ² = L ₂₁ ² + (L ₂₂ + L) ² −2L ₂₁ (L ₂₂ + L) cosζ (10)
(Equation 11)
u = Rcosψ (11)
(Equation 12)
v = Rsinψ (12)
(Equation 13)
w = x−u (13)
(Equation 14)
OP ² = (H−v) ² + (w + D) ² (14)
(Equation 15)
β ₁ = tan ⁻¹ {(H−v) / (w + D)} (15)
(Equation 16)
β ₂ = cos ⁻¹ {(−L ₂ ² + L ₁ ² + OP ² ) / (2L ₁ · OP)} (16)
(Equation 17)
γ ₁ = β ₂ −β ₁ (17)
(Equation 18)
γ ₂ = γ ₁ + γ ₃ −π / 2 (18)
(Equation 19)
γ ₃ = cos ⁻¹ {(−OP ² + L ₁ ² + L ₂ ² ) / (2L ₁ · L ₂ )} (19)
(Equation 20)
β ₃ = β ₄ −γ ₂ (20)
(Equation 21)
β ₄ = cos ⁻¹ [{−L ₂₁ ² + L ₂ ² + (L ₂₂ + L) ² }
/ {2L ₂ (L ₂₂ + L)}] (21)
(Equation 22)
θ = 3π / 2−ψ + β ₃ (22)

  As described above, the function f “θ = f (ψ, x)” can be specifically determined. Thereby, a variable conversion means for converting the function y (ψ, x) into the function y (θ) can be realized. That is, by simultaneously measuring the measurement variables y, x, and ψ, it is possible to obtain the function y (θ) as it is without removing the workpiece supported rotatably on the rotary shaft. It has been shown.

  In FIG. 4, the block diagram (conceptual figure) of the cylindrical grinding machine 100 of a present Example is shown. According to the cylindrical grinding machine 100, the measurement variables y, x, and ψ can be measured simultaneously. The distance x between the C axis and the W axis is controlled by a servo control mechanism such as a driver 12. Further, the rotation angle ψ of the C axis is controlled by a servo control mechanism such as a driver 13. The CNC device 10 controls the drivers 12 and 13 via the interface (IF) 11. In addition, 14 and 15 are sine wave signal branching units, and 16 and 17 are waveform shapers.

  If the cylindrical grinding machine 100 is configured in this way, the measured values of the measurement variables y, x, and ψ can be simultaneously transferred to the personal computer (PC) 19 via the conversion board 18 in real time. Therefore, if the above relationship is used, the function y (θ) can be obtained from the measurement variables y, x, ψ and the like by the personal computer 19.

If the function y (θ) is specifically obtained as described above, y (θ) can be developed into the form of Equation (3) by Equations (4) to (6) and harmonic analysis. However, it is assumed that a convenient numerical value is selected for α. At this time, since c _n and φ _n are determined for all n satisfying 1 ≦ n ≦ J, r (θ) can be specifically obtained as a function of θ as shown in equation (1) (roundness) Degree calculation means).

Further, if the personal computer 19 and the CNC device 10 are connected with a communication line as shown in the figure, the roundness calculation means on the personal computer 19 side and the X axis correction amount δx obtained by the correction amount calculation means are used as the CNC device 10. Can be contacted automatically and quickly.
Hereinafter, a means for calculating the correction amount δx (correction amount calculation means) will be described.

  FIG. 5 shows how to obtain the correction amount δx (ψ) for making r (θ) constant regardless of θ. However, here, the correction amount δx (ψ) is a correction amount for the distance x (ψ) between the CWs corresponding to each rotation angle ψ (FIG. 2), that is, a correction amount for the movement amount of the grindstone table 9. .

As is clear from this figure, the main correction amount δx (ψ) can be obtained by the following equations (23) to (28), for example.
(Equation 23)
θ = π−ψ−η (η≡∠CWO) (23)
(Equation 24)
δr (θ) = r (θ ) -λ I a m (λ I ≧ 1) ... (24)
(Equation 25)
δx = δr (θ) / cos η (25)
(Equation 26)
cos η = w / OW = w / (v ² + w ² ) ^1/2 ≡g (x, ψ)
= (X-R cosψ)
/ {(R sinψ) ² + (x−R cosψ) ² } ^1/2 (26)
(Equation 27)
η = cos ⁻¹ {g (x, ψ)} (27)
(Equation 28)
δx (x, ψ) = [r (π−ψ−cos ⁻¹ {g (x, ψ)})
1-? _I a _m] / g (x, ψ) ... (28)

However, λ _I in Equations (24) and (28) is a safety factor to prevent the cylinder from being over-machined. Grinding → Measurement → Grinding → Repeat measurement when machining the crankpin (eccentric cylinder) This is a number that should approach 1 each time the number of cycles (cycle number) I increases. Therefore, when the final value of I is small, the value of λ _I may be fixed to 1 from the beginning.

As described above, the correction amount δx (ψ) can be obtained. Therefore, if the X-axis value x (ψ) with respect to the previous ψ is used, the X-axis value x ′ (ψ) with respect to the next ψ can be obtained by the following equation (29).
(Equation 29)
x ′ (ψ) = x (ψ) −δx (ψ) (29)

  If the cylindrical grinding machine 100 is configured as described above, it is possible to automatically perform the circular processing of the eccentric cylinder without removing the workpiece supported rotatably on the rotating shaft outside the machine.

As a result of configuring the cylindrical grinding machine 100 as described above, the following effects could be obtained.
(A) The roundness of the eccentric cylinder can be measured on the machine tool, and the phase angle deviation error between the measurement data and the machining data is eliminated.
(B) When the center of the eccentric cylinder can be measured without matching the rotation center of the measuring instrument, and as a result, a plurality of workpieces having different eccentricity, eccentric cylinder radius, or eccentric phase angle are ground. Also, the roundness can be measured by one chucking operation.
(C) It has become possible to automatically correct the wheelhead profile data.
(D) Since the displacement measurement by the V gauge method is performed, the measurement range of the measurement unit is reduced, and the environmental resistance against a temperature or the like that becomes a problem when the measuring machine is mounted on the machine is improved.

  In addition, even if the personal computer 19 is not provided in the cylindrical grinding machine 100 of FIG. 4, it is possible to constitute this mechanism. In such a case, for example, a method in which the output of the conversion board 18 is directly input to the CNC device 10 and the above-described roundness calculation means and correction amount calculation means are realized by the CNC device 10 is also conceivable.

  Further, the measuring instrument sliding means of the cylindrical grinding machine 100 of the present embodiment is fixed to the grinding wheel base 9, but the measuring instrument sliding means does not necessarily have to be interlocked with the grinding wheel base. Further, the measuring instrument sliding means of the cylindrical grinding machine 100 of the present embodiment is realized by a link mechanism, but the measuring instrument sliding means does not necessarily need to be configured by a link mechanism.

In these cases as well, in general, a variable conversion means such as a function f can be realized by using constants (sliding mechanism parameter groups of individual devices) such as the length and angle of each part of the measuring instrument sliding means and machine tool. it can.
That is, in these cases, the function y (θ) can be obtained from the constants and measurement variables representing the structure related to the posture of the measuring instrument sliding means by means of the present invention. The effect by this invention can be acquired.

  Further, in the first embodiment, as described above, “measurement variables y, x, and ψ are simultaneously measured, so that the function y can be directly used without removing the workpiece supported rotatably on the rotating shaft. It is possible to obtain (θ) ”, but as a specific method for simultaneously measuring the measurement variables y, x, and ψ, for example, the following examples can be considered.

(Method 1) Method of measuring at a fixed time period Measurement is performed at a fixed time period by a measurement start signal. At this time, for example, when the C-axis is rotated at a constant speed, the number of measurement points can be determined from the time required for one rotation of the workpiece obtained from the rotation speed and a predetermined measurement time period (fixed time interval). .

(Method 2) Method of measuring at a constant rotation angle period When the C-axis (rotation angle ψ) rotates by a constant angle, a synchronization signal is generated, and each measurement of y and x is performed in parallel using this signal as a synchronization reference.
Further, x may be used instead of ψ. That is, for example, when x is positioned at each predetermined coordinate (measurement point), a synchronization signal may be generated, and each measurement of ψ and y may be performed in parallel using this signal as a synchronization reference.

(Method 3) Method of using servo control command value In addition to the above-mentioned ψ and x, the command value used for physical control (servo control) of the rotation of the C axis and the movement of the grinding wheel base is used. It is also possible to do. In this case, however, the following delay in the servo control can be sufficiently ignored, and it is a condition that the grindstone table and the workpiece (cylinder) move with sufficiently high accuracy with respect to the command value.

  The present invention can also be effectively used as a roundness measuring device that does not have grinding means such as a grindstone. That is, since r (θ) can be obtained even in such an apparatus, it can be used as a roundness measuring apparatus.

  For example, the motion parameter ξ related to the mechanical motion of the measuring instrument sliding means as shown in the first embodiment is detected, and the position of the axis of the eccentric cylinder (eccentricity to be rounded) is detected based on the motion parameter ξ. If the amount R and the rotation angle ψ (FIG. 2) are accurately obtained, it is possible to carry out a more accurate circular processing.

FIG. 6 is a schematic cross-sectional view of a cylindrical grinder 200 having a rotation angle sensor (rotary encoder RE) according to the second embodiment. This cylindrical grinding machine 200 is provided with a rotary encoder RE (rotation angle sensor) at the position of the first pivot P of the cylindrical grinding machine 100 (FIGS. 1 and 2) of the first embodiment. The rotary encoder RE is clockwise as the positive direction toward the FIG. 6 from the original line PP2 with a rotation angle gamma ₁ of the first arm 1 on the horizontal plane containing the P (first pivot) point in FIG. It is to be measured.
That is, the motion parameter ξ corresponds to the rotation angle γ ₁ of the first arm 1 in this embodiment. In FIG. 6, points P1 and P2 are points on a perpendicular line hanging from the point P ′ (second pivot).

For example, according to such an apparatus (cylindrical grinding machine 200), as will be described in detail later with reference to FIGS. 7 to 9, the phase angle error Δψ related to the position of the axis of the eccentric cylinder to be rounded is obtained. More accurate eccentricity R can be obtained.
Further, the obtained phase angle error Δψ can be used, for example, for correcting the rotation angle ψ of the C-axis when the perfect circle machining is executed by the synchronization control means. Further, if a more accurate eccentric amount R is obtained, the moving amount x of the grindstone table 9 at the time of executing the circular processing can be determined with higher accuracy.
Further, instead of correcting the rotation angle ψ of the C axis based on the phase angle error Δψ, the timing for realizing the movement amount x by the time corresponding to the phase angle error Δψ may be shifted by the synchronization control means.

FIG. 7 is a general flowchart of the measurement main program A0 for controlling the cylindrical grinding machine 200.
In this program A0, first, in step a10, the grindstone base 9 is brought close to the C axis to a position where the measuring device (three-point contact type measuring instrument) can be inserted, and the outer side of the eccentric cylinder (eg, crank pin) is placed. Insert the measuring device into the workpiece (eg crankshaft etc.) so that the horse riding gauge (V block) contacts the circumference.

Next, in step a20, the three-point contact measuring device (V block) is moved in contact with the side surface of the eccentric cylinder by the measuring device sliding means based on the predetermined profile data as a reference, and the circumference K Synchronous control is performed so that (FIG. 3) always contacts the contact surfaces A and B (FIGS. 3 and 6) of the V gauge 25 (V block) and the grindstone (FIG. 6) at a total of three points. However, the C axis is rotated once from an arbitrary position (angle) in the direction in which the rotation angle ψ increases (counterclockwise in FIG. 2). Simultaneously with the execution of this synchronous control, the rotation angle ψ at the origin O (the position of the eccentric cylinder shaft), the position x of the grindstone, and the rotation angle γ ₁ of the first arm 1 are measured and recorded. To do.

The origin O when performing this measurement makes a round on the circular orbit S of FIGS. 1, 2, and 6. The interval between the measurement points (measurement point density) at this time is, for example, a round on the circular orbit S. Evenly, it is acceptable.
Further, for example, if the measurement point density in the vicinity of each intercept with respect to the X axis and the Y axis of the circular orbit S on the XY coordinate plane in FIG. 6 is made particularly high, the calculation in subroutines B0 and C0 described later can be performed with high accuracy. It is relatively convenient to do.

In step a30, it is determined whether or not the measurement in step a20 has been performed a predetermined required number of times.
In step a40, the rotational movement of the C axis and the translational movement of the x axis are stopped.
In step a50, the measuring device (three-point contact type measuring device) is raised and the grindstone base 9 is moved backward.

In step a60, a phase angle error calculation subroutine B0 (FIG. 8) described later in detail is called to calculate the phase angle error Δψ of the origin O.
In step a70, an eccentricity calculation subroutine C0 (FIG. 9), which will be described later in detail, is called to calculate the eccentricity R of the origin O.
In step a80, based on the phase angle error Δψ of the origin O calculated by the subroutines B0 and C0 and the eccentric amount R, the synchronization control data (profile data) used for the circular processing of the eccentric cylinder is corrected.

  The phase angle error Δψ obtained in this way can be used, for example, for correction of the rotation angle ψ of the C axis when the perfect circle machining is performed by the synchronization control means. Moreover, if the more accurate eccentric amount R is used, the movement amount x of the grindstone table 9 at the time of executing the circular processing can be determined with higher accuracy.

FIG. 8 is a flowchart of the phase angle error calculation subroutine B0 called from the measurement main program A0.
In this subroutine B0, first, in step b20, an extreme value (minimum value <0, 0 <maximum) with respect to the _first derivative dγ ₁ / dψ due to the rotation angle ψ of the rotation angle γ ₁ of the first arm 1. Rotation angles ψ ₁ and ψ ₂ giving a value) are theoretically calculated based on the equations (10) to (17). However, this calculation is theoretical and is independent of the measurement of the program A0. Therefore, the calculation may be performed in advance before the program A0 is executed.

Next, in step b40, the measurement data of the rotation angle γ ₁ and the rotation angle ψ is analyzed, and the rotation angle when the change rate of γ ₁ with respect to ψ is the maximum (> 0) and the minimum (<0). The values ψ ₁ and ψ ₂ of ψ are obtained. However, when the measurement point density is uniform on the circular orbit S, the values of the rotation angles ψ when the change amount of γ ₁ is the maximum (> 0) and the minimum (<0) are respectively ψ ₁ , it may be as Ψ _2. When the measurement point density is relatively rough, Ψ ₁ and Ψ ₂ may be obtained by using various interpolation operations such as parabolic approximation known in the field of numerical analysis.

Next, in step b60, the phase angle error Δψ of the origin O is calculated by the following equations (30), (31), (32).
(Equation 30)
Δψ ₁ = ψ ₁ −ψ ₁ (30)
(Equation 31)
Δψ ₂ = ψ ₂ −ψ ₂ (31)
(Expression 32)
Δψ = (Δψ ₁ + Δψ ₂ ) / 2 (32)

For example, as described above, by using the measured value of the rotation angle ψ when the rate of change of γ ₁ with respect to ψ is the maximum (> 0) or the minimum (<0), the constant measurement accuracy of the rotary encoder RE On the other hand, the value of the phase angle error Δψ can be obtained with the highest accuracy.

Further, the value of Δψ ₁ may be obtained by the following equation (33).
(Expression 33)
Δψ ₁ = (γ ₊ −Γ ₊ ) / (dγ ₁ / dψ) ₊ (33)
Here, Γ ₊ is a theoretical value at ψ = 0 of γ ₁ that can be theoretically obtained from the above equations (10) to (17), and γ ₊ is γ ₁ actually measured by the program A0. The actual measurement value when ψ = 0. Further, (dγ ₁ / dψ) ₊ is a theoretical value at ψ = 0 of the first derivative of γ ₁ theoretically obtained based on the equations (10) to (17).

As can be seen from FIG. 6, in reality, the sensitivity of the rotary encoder RE with respect to small angle fluctuations of ψ is considered to be the highest or sufficiently high in the vicinity of ψ = 0, π. For example, the actual measured value of γ ₁ as described above can be used without being limited to the measured value of γ ₁ at the position of the maximum).
Since Equation (33) is based on linear approximation, it is effective when Δψ ₁ is sufficiently small so that the amount of change in (dγ ₁ / dψ) ₊ with respect to the amount of change in ψ can be sufficiently ignored.

Similarly to the above, the value of Δψ ₂ may be obtained by the following equation (34).
(Equation 34)
Δψ ₂ = (γ ₋ −Γ ₋ ) / (dγ ₁ / dψ) ₋ (34)
Here, Γ ₋ is a theoretical value at ψ = π of γ ₁ that can be theoretically obtained from the above equations (10) to (17), and γ ₋ is γ ₁ actually measured by the program A0. This is an actual measurement value when ψ = π. Further, (dγ ₁ / dψ) ₋ is a theoretical value at ψ = π of the first derivative of γ ₁ theoretically obtained based on the equations (10) to (17).

Further, when using the equation (33), more preferably, first, the angle ψ ₊ that gives the maximum value with respect to (dγ ₁ / dψ) is theoretically calculated in advance from the equations (10) to (17). Γ ₊ is a theoretical value at ψ = ψ ₊ of γ ₁ that can be theoretically obtained from the above equations (10) to (17), and γ ₊ is γ actually measured by the program A0. The actual measurement value when ψ = ψ ₊ of ₁ is good. At the same time, (dγ ₁ / dψ) ₊ is a theoretical value at ψ = ψ ₊ of the first derivative of γ ₁ theoretically obtained based on the equations (10) to (17).

The reason why these conditions are more desirable is that the above-described γ ₁ is a periodic function having a relatively good property with respect to the rotation angle ψ (differentiable three or more times), and according to such a method, the second derivative of γ ₁ is This is because d ² γ ₁ / dψ ² ≈0 is satisfactorily satisfied in the vicinity of ψ = ψ ₊ , so that even if the width of Δψ ₁ is slightly large, around 1 °, the expression (33) is established with sufficiently high accuracy. These circumstances are the same when the equation (34) is used.

FIG. 9 is a flowchart of an eccentricity calculation subroutine C0 called from the measurement main program A0.
In this subroutine C0, first, in step c20, data measured by the measurement main program A0 is retrieved. That is, when the axis of the eccentric cylinder (the origin O) is at a position (O _a , O _{b in} FIG. 6) where the value of the rotation angle (ψ + Δψ) corrected using Δψ is ± π / 2. The measured values of the rotation angle γ ₁ of the first arm 1 and the position x of the grindstone table 9 are searched from the measurement data. However, if the measurement point density is relatively rough, rotation at each point (O _a , O _{b in} FIG. 6) using various interpolation operations such as parabolic approximation known in the field of numerical analysis, for example. The value of the angle γ ₁ may be obtained. In this case, the value of the position x of the grindstone base 9 at each position (O _a , O _{b in} FIG. 6) may be similarly calculated by a predetermined interpolation calculation.

In step c40, the origin O _a, each of the O _b Y coordinate Y _a, following equation Y _b (35), (36), it is calculated by (37).
(Equation 35)
Y = Y1-Y2 (35)
(Equation 36)
Y1 = H + L ₁ sinγ ₁ (36)
(Equation 37)
Y2 = {L ₂ ² − (x + D−L ₁ cos γ ₁ ) ² } ^1/2 (37)

Here, Y1 is the Y coordinate of the second pivot P '. Y2 is a width (height) when a line segment OP ′ connecting the origin O (O _a , O _b ) and the second pivot P ′ is projected on the Y axis, in other words, L ₂ cosγ ₂ (FIG. 2, the length corresponding to FIG. Therefore, for example, when the axis of the eccentric cylinder is located at the point O _a , the length Y2 coincides with the length of the line segment P′P1 in FIG.

For example, the Y-coordinate Y _a of the origin O _a To find these equations, equation (36), the gamma ₁ (37), the value of the rotational angle after correction [psi (rotation angle [psi + [Delta] [phi] before correction) + [pi The measured value of γ ₁ (γ _{13 in} FIG. 6) at the time of / 2 is substituted, and the measured value of the position x at that time is substituted for x in formula (37), and finally, formula (35) Y _a may be calculated from
For the position of the origin O _b , γ ₁ = γ ₁₄ etc. is substituted into each equation in the same manner, and the Y coordinate Y _b is obtained.

Next, in step c60, the eccentric amount R of the eccentric cylinder is calculated by the following equations (38), (39), (40).
(Equation 38)
R ₃ = Y _a (38)
(Equation 39)
R ₄ = −Y _b (39)
(Equation 40)
R = (R ₃ + R ₄ ) / 2 (40)

  By configuring and controlling the cylindrical grinding machine 200 as described above, the trueness of an eccentric cylinder such as a crank pin can be obtained without removing a workpiece rotatably supported by a rotating shaft such as a crank shaft. Circular machining can be performed automatically and with higher accuracy.

As a result of configuring and controlling the cylindrical grinding machine 200 as described above, the following effects could be obtained.
(A) The roundness of the eccentric cylinder can be measured with high accuracy on the machine tool, and there is no phase angle deviation error between the measurement data and the machining data.
For example, when a crank pin of a crank shaft of a gasoline engine having a plurality of cylinders is machined into a perfect circle, each crank pin can be formed at a desired accurate angle with respect to the crank journal. The ignition timing inside the engine became extremely accurate, and the engine output could be improved, and the vibration, noise and fuel consumption of the engine could be greatly reduced.

(B) When the center of the eccentric cylinder can be measured without matching the rotation center of the measuring instrument, and as a result, a plurality of workpieces having different eccentricity, eccentric cylinder radius, or eccentric phase angle are ground. Also, the roundness can be measured with high accuracy by one chucking operation.
For example, when a crank pin of a crank shaft of a gasoline engine having a plurality of cylinders is processed into a perfect circle, each crank pin can be formed with a desired accurate eccentric amount with respect to the crank journal. For this reason, the stroke (eccentric amount × 2) of each piston becomes extremely accurate, and the compression ratio of the ignited gas in each cylinder can be realized very accurately. As a result, there is no variation in the compression ratio of each cylinder, and the output of each cylinder can be balanced as designed, which greatly reduces engine vibration, noise, and fuel consumption.

(Sliding mechanism parameter automatic correction means)
With the replacement, repair or adjustment of the three-point contact type measuring instrument or V block, for example, the aforementioned sliding mechanism parameter group (D, H, R, L) related to the attitude of the measuring instrument sliding means (or V block sliding means) ₁ , L ₂₁ , L ₂₂ , ζ), etc. may need to be corrected.
For example, this is the case when the V block is replaced due to wear or breakage, or the change of the sandwiching angle α.

For example, in the case of the cylindrical grinding machine 200 (FIGS. 2 and 6) having the rotation angle sensor of the second embodiment, when the V block is changed to change the sandwiching angle α, L ₂₂ and L in FIG. The value of will change. However, since the cylindrical grinding machine 200 has a rotation angle sensor (rotary encoder RE), if the following procedure is followed, the values of L ₂₂ and L that have once become indefinite due to replacement of the V block will be described. Can be reset automatically.

(1) radius a _m not eccentric with respect to the C-axis is accurately prepare known gauge cylinder. However, the gauge cylinder may be configured as a part of the machine tool from the beginning, or it may be a workpiece in a work whose cylinder radius is precisely circularly processed with the C axis as an axis. May be present.
(2) to the computer which constitutes a part of the cylindrical grinding machine 200, and inputs or specifies the radius a _m of nip angle α and the gauge cylinder V-block.

(3) The cylindrical grinding machine 200 automatically resets the values of L ₂₂ and L in the following procedure.
(A) The value of L is reset by the following equation (41).
(Equation 41)
_{L = a m / sin (α} / 2) ... (41)
(B) The V block (horse riding gauge) is brought into contact with the gauge cylinder at two points, and the end face of the measuring element of the measuring instrument is brought into contact with the gauge cylinder.

(C) Maintaining this contact state, the measurement point s having the zero point as the reference point d (reference point d of the V gauge 25) of the three-point contact measuring instrument is set as the position of the end face of the current probe. By substituting the value of “L−a _m ”, the zero point of the reference point d is adjusted. Here, s is a positive direction in which the measuring element tends to extend toward the axis of the gauge cylinder. Thereby, the value at the reference point d of the measurement parameter s can be reset to 0.

(D) The output value γ ₁ of the rotary encoder RE is detected.
Based on the equation (e) (10) to (17), substitutes the value of the known variables (sliding kinematic parameters) to the solved for pre L ₂₂ wherein determining the value of L _22. (However, at this time, because the gauge cylinder is not eccentric due to the above setting, R = 0 and ψ is arbitrary.)

For example, according to the above-described method, correction or adjustment of the values of some of the sliding mechanism parameters (L ₂₂ and L) is automatically performed based on the measured value of the motion parameter ξ (γ ₁ ). It becomes possible to carry out, and the work efficiency of the work accompanying the replacement, repair or adjustment of the three-point contact measuring instrument or V-block is greatly improved.

(Sequential asymptotic circular processing)
Using the cylindrical grinding machine 200 in the second embodiment, “measurement of phase angle error Δψ of cylindrical axis (program A0 (subroutine B0)) → measurement of eccentric amount R of cylindrical axis (subroutine C0) → axis By repeating the rounding cycle consisting of the steps of `` Position correction → Roundness measurement → Round grinding '', gradually rounding the rounding process while increasing accuracy, and asymptotically High precision round processing can be performed.

  In particular, when performing highly accurate round processing asymptotically in multiple stages in this way, it is necessary and sufficient to obtain the phase angle error Δψ using equations (32) to (34). Since accuracy is obtained and calculation is simplified, both programming time and operation processing time are shortened, which is convenient.

(Skip measurement process (Omit process))
In such a case, for example, the measurement of the position of the central axis of the eccentric cylinder in the circular processing of the eccentric cylinder may be performed as many times as necessary in consideration of the required processing accuracy.
Accordingly, “measurement of phase angle error Δψ of cylinder axis (program A0 (subroutine B0)) → measurement of eccentric amount R of cylinder axis (subroutine C0) → correction of axis position → measurement of roundness → roundness When the perfect circle machining cycle composed of each process of “grinding” is repeated and the perfect circle machining is repeated stepwise many times (that is, asymptotically asymptotically), for example, the phase angle error of the axis of the eccentric cylinder In the measurement process of Δψ, etc., the remeasurement may be omitted after the mth (predetermined number of times m ≧ 2) and thereafter.

  For this reason, for example, under the condition that at least one of the phase angle ψ of the central axis of the eccentric cylinder to be processed viewed from the C axis (rotation axis) or the eccentric amount R is determined to have converged, After performing the convergence condition determination process, at least one of these positioning processes may be omitted.

  Therefore, for example, after the m-th cycle when a predetermined convergence condition is satisfied, the above-described circular processing cycle is changed to “measurement of the eccentric amount R of the cylindrical shaft R (program A0 (subroutine C0)) → correction of the shaft position → true By appropriately changing (simplifying) the measurement of roundness → round grinding or “roundness measurement → round grinding” etc., the execution efficiency of the subsequent round machining cycle can be further increased. It is also possible to improve.

  The natural number m may be a fixed value determined from the beginning, or may be dynamically determined according to a determination result such as whether or not a predetermined convergence condition is satisfied.

  FIG. 10 is a schematic side view (a) and a front view (b) of a three-point contact measuring instrument 700 according to the third embodiment. This three-point contact type measuring instrument 700 is an improved part of the three-point contact type measuring instrument (8, 22, 25, 27 in FIG. 1) of the cylindrical grinding machine 100 of the first embodiment. The main feature is that two V blocks with different α can be mounted simultaneously.

For this reason, if the three-point contact measuring instrument 700 is used, the angle θ of the equation (22) or the equation (23) (FIG. 2 or FIG. Every time (m ≧ 1), two types of V blocks can be alternately exchanged for use in measuring roundness.
FIG. 11 is a table showing an enlargement ratio with respect to each spectral component (order) of the true circle error of the three-point contact type measuring instrument 700. However, the content of the row “α = 60 °” in this table is the same as the content of the column “α = 60 °” in FIG.

  For example, if such a combination of binary values (45 °, 60 °) is applied, the roundness error is within the range up to the maximum order n (10 ≦ n ≦ 50) that is necessary or sufficient for practical use. The absolute value of each enlargement factor for each of the spectral components (order) can be secured at a suitable value of 1.00 or more. For this reason, if this three-point contact type measuring instrument 700 is used, it becomes possible to measure the roundness with sufficiently high accuracy without performing the work of exchanging the V block by hand.

  In addition, by fixing the sandwiching angle of the V block to, for example, α = 80 ° (≈1.40 [rad]), the absolute value of each enlargement factor is practically used for each order necessary or sufficient for practical use. It is possible to ensure a value equal to or higher than a predetermined lower limit (> 0) that can withstand the above. Therefore, depending on the required measurement accuracy of roundness, it is not always necessary to prepare two or more types of V blocks by selecting an appropriate sandwich angle α.

  FIG. 12 is a schematic front view (a) of a three-point contact type measuring instrument 800 according to the fourth embodiment, and an alternative configuration diagram (b) in which a part thereof is alternatively modified. This three-point contact type measuring instrument 800 (a) is an improvement of a part of the three-point contact type measuring instrument (8, 22, 25, 27 in FIG. 1) of the cylindrical grinding machine 100 of the first embodiment. , One at each of the bisectors of the sandwich angle α, that is, at different positions (Θ = Θ1, Θ2) of the angle Θ (phase viewed from the origin O) from the V-block center line (Θ = 0), A major feature is that a total of two weighing sensors (sensor I and sensor II) are equipped.

With such a configuration, the measuring sensor (sensor II) provided in the range of “0 ≦ Θ2 <Θ0” is the above-mentioned “Mechanical Journal of the Japan Society of Mechanical Engineers Vol. It can be used as a weighing sensor in the V-block type measurement method described in "Method" (May 1950). In addition, a weighing sensor (sensor I) provided in a range of “Θ0 <Θ1 <Θ0 ′” can be used as a weighing sensor in the riding gauge type measurement method described in the same paper.
However, in the three-point contact measuring device 800 (a), the range of “0 ≦ Θ <Θ2 and Θ0 ′ <Θ <2π” has an insertion opening as a space for inserting an eccentric cylinder.

  Further, the three-point contact type measuring instrument 800 (a) keeps the sensor II in the direction of the x2 axis in FIG. 12 while maintaining the angle Θ2 from the center line (Θ = 0) of the V block 25 at a constant value. A translation adjustment mechanism capable of adjusting the position (translation). Further, the translation amount x2 can be read and reset as needed by a positioning mechanism built in the pedestal 24 of the three-point contact measuring instrument 800 (a). Therefore, this translation adjustment mechanism can give a large degree of freedom to the radius of the workpiece (eccentric cylinder) to be measured.

  Furthermore, each weighing sensor (sensor I, sensor II) may be provided with a translational adjustment mechanism that can adjust the position (translate) in the weighing direction. This makes it possible to give a large degree of freedom to the radius of the workpiece (eccentric cylinder) to be measured even when the measuring sensor's positioning range (or high-precision positioning range) is relatively narrow. It becomes.

Further, if the average radius a ₀ of the eccentric cylinder is obtained in advance using the sensor I according to the first embodiment (Equation (5), Equation (6)), the above-described translational adjustment mechanism is used to obtain the eccentric cylinder. It is also possible to automate the resetting (optimization) of the position (translation amount x2) of the sensor II accompanying the change of the radius (average radius a ₀ ).

Further, when the average radius a ₀ of the eccentric cylinder is known in advance and the position (value of x2) of the sensor II is fixed (optimized) based on this, the sensor I and the sensor II are simultaneously used. Since the roundness can be measured by using the three-point contact measuring instrument 800 (a), the three-point contact measuring instrument 700 of the third embodiment is used in this case. It is possible to measure the roundness in about half the measurement time.

FIG. 13 is a table showing each enlargement ratio for each spectral component (order) of the true circle error of the three-point contact type measuring instrument 800 (a). However, for the sensor I (Θ1 = 180 °), the enlargement ratio with respect to each order is obtained according to the theory of the horseshoe gauge measurement method, and for the sensor II (Θ2 = 45 °), according to the theory of the V block measurement method. The expansion ratio with respect to the order was obtained.
With such a setting, the absolute value of the enlargement ratio can be set to 1.00 or more for each order required for measuring the roundness, and at the same time, “0 ≦ Θ <45 ° and Θ0 ′. The entire range of <Θ <360 ° can be left as a space for inserting an eccentric cylinder (insertion opening).

For example, if a three-point contact measuring device is configured in this way, high-precision roundness measurement can be realized, and at the same time, mechanical operations such as insertion and elevation of the measuring device can be easily automated. Will be able to.
That is, due to these actions, the three-point contact measuring instrument 800 (a) can efficiently and accurately perform a perfect circle process.

Moreover, the alternative configuration diagram (b) of FIG. 12 shows an alternative configuration in which the translational adjustment mechanism of the sensor II that can be translated on the pedestal 24 of the three-point contact measuring instrument 800 (a) is modified. Is.
The pedestal 24 in the alternative configuration diagram (b) incorporates a rotation adjustment mechanism capable of rotating the sensor II around the point C2 as the rotation center, and, like the translation adjustment mechanism described above, the measurement target. According to the average radius a _{0 of the} cylinder, the position of the intersection (origin O) of each measuring direction line of the sensor I and the sensor II can be moved (adjusted).

However, since the rotation angle Θ2 centered on the point C2 in the above rotation adjustment mechanism always coincides with the phase Θ2 in the measuring direction of the sensor II shown in the front view (a) of FIG. When the dynamic adjustment mechanism is used, it is necessary to recalculate the row of Θ2 in the enlargement ratio table of FIG. 13 every time after the rotation adjustment is performed in accordance with the change of the phase Θ2.
For example, even if such a cylindrical center adjusting means is used, the same effects as those of the three-point contact type measuring instrument 800 (a) can be obtained.

Note that the correction of the profile data of the workpiece (eccentric cylinder) in the perfect circle processing using the present invention may be performed so that the eccentric amount R finally becomes 0, for example.
In other words, the present invention can also be applied to precise measurement of the position of a journal shaft rotatably supported by, for example, a C-axis (rotating shaft) and perfect circle processing.

  For example, more specifically, a workpiece supported by the C-axis (rotary shaft), such as a crank journal of a crankshaft, may have a slight machining error due to changes in rigidity or grinding resistance. However, if the profile data is corrected (feed forward) based on the positioning of the central axis of the cylinder or the measurement of the roundness based on the present invention, the above-described case may occur. It is also possible to realize highly accurate circular processing of a journal or the like supported by a simple C axis (rotating axis).

In the present specification, the following inventions are also recognized.
That is, the first means is a roundness measuring apparatus for measuring the roundness of a cylinder integrally formed with a workpiece rotatably supported by a rotary shaft and eccentric from the rotary shaft. Three-point contact type measuring instrument that measures by the contact method, measuring instrument sliding means for moving the three-point contact type measuring instrument along the circumference on the cross section perpendicular to the rotation axis of the cylinder, and this roundness measuring device Position measuring means for measuring the relative position x of the rotation axis with respect to the above, rotation angle measuring means for measuring the rotation angle ψ around the rotation axis of the cylinder, and the roundness of the cylinder rotating around the rotation axis as the relative position x, the rotation angle ψ, and the roundness calculation means for calculating from the output value y of the three-point contact type measuring instrument.

  The second means is the same as the first means described above, having an origin O located at or near the center of the circumference and a predetermined original line OC starting from the origin O, and the circumference is on the coordinate plane. The position coordinates (r, θ) of the measurement point p of the output value y on the circumference are expressed using the two-dimensional polar coordinates fixed to, and the relative position x and the rotation at the measurement of the output value y at the measurement point p Using the variable transformation “θ = f (ψ, x, Λ)” for obtaining the angle coordinate θ from the angle ψ and a set of constants Λ representing the structure related to the posture of the measuring instrument sliding means, each on the circumference The variable conversion means for obtaining the output value y at the measurement point p as a function y (θ) of the angle coordinate θ is provided.

Further, the third means uses the analysis technique such as harmonic analysis in the second means described above to express the distance r from the origin O of each measurement point p on the circumference from the function y (θ) as an angular coordinate. The function r is obtained by means of a radius calculation means obtained as a function r (θ) of θ and a variable inverse transformation “ψ = f ⁻¹ (θ, x, Λ)” with respect to the variable transformation f in the opposite direction with respect to the angle coordinate θ and the rotation angle ψ. A variable inverse conversion means for converting (θ) into a function r (ψ) of the rotation angle ψ, and a correction amount for obtaining the correction amount δx for the relative position x during grinding of the cylinder as a function δx (ψ) of the rotation angle ψ. And calculating means.

  Further, a fourth means includes the three-point contact measuring instrument according to any one of the first to third means, wherein the three-point contact type measuring device includes a plurality of V blocks having different sandwiching angles α formed by the two contact surfaces. Alternatively, a weighing sensor is provided at each of a plurality of positions having different phases Θ as viewed from the origin O located at or near the center of the circumference.

  The fifth means is the same as the fourth means described above, in which the two bisectors having different sandwiching angles α are made to coincide with each other for the plurality of V blocks, and are shared by the plurality of V blocks. The weighing direction line of the weighing sensor is arranged on this bisection plane.

Further, the sixth means is that in the fourth means described above, at least one of the plurality of weighing sensors is modified by correcting the position or measuring direction of the self-measuring sensor in accordance with the average radius a _{0 of the} cylinder. Cylindrical center adjusting means for adjusting the position of the intersection of the straight lines extending from each weighing sensor in each weighing direction is provided.

A seventh means includes a motion sensor for detecting a motion parameter ξ related to the mechanical motion of the measuring device sliding means and a three-point contact measuring device in the means of any one of the first to sixth aspects. The correction of the value of at least one constant belonging to the set Λ, which is necessary in connection with the replacement, repair or adjustment of the above, is the motion parameter ξ when _measuring the central axis of the gauge cylinder whose radius a _m and the central coordinates are known And a sliding mechanism parameter automatic correcting means that is automatically executed based on the measured value.

  The eighth means includes a motion sensor for detecting a motion parameter ξ related to the mechanical motion of the measuring instrument sliding means, and a circumference of the eccentric cylinder in the means of any one of the first to seventh aspects. Origin positioning means for measuring a position coordinate viewed from the rotation axis of the origin O fixed at or near the center based on the relative position x, the rotation angle ψ, and the motion parameter ξ or related values of these variables; It is to provide.

  The ninth means is the rotation angle sensor for measuring the angle of the arm for realizing the mechanical movement in the seventh or eighth means, or the arm for measuring the length of the arm. It is to make it a long sensor.

  The tenth means is a cylindrical shaft positioning device that is integrally formed with a workpiece rotatably supported by a rotating shaft and measures the position of the central axis of the cylinder eccentric from the rotating shaft. A V-block sliding means for moving the V-block in contact with a circumference on a cross section perpendicular to the axis, a position measuring means for measuring a relative position x of the rotation axis with respect to the positioning device, and a rotation angle ψ about the rotation axis of the cylinder A rotation angle measuring means for measuring the movement angle, a movement sensor for detecting a movement parameter ξ related to the mechanical movement of the V block sliding means, and the rotation axis of the origin O fixed at or near the center of the circumference. It is to provide an origin positioning means for measuring the position coordinates based on the relative position x, the rotation angle ψ, the motion parameter ξ, or the related values of these variables.

  The eleventh means may be a movement angle sensor that measures the angle of the arm that realizes the mechanical movement, or an arm length that measures the length of the arm. It is to make a sensor.

  In the twelfth means, in the origin positioning means of the tenth or eleventh means, first, a phase angle error Δψ from a predetermined standard position of the origin O is obtained, and then, with respect to the rotation angle ψ. The position coordinate of the origin O viewed from the rotation axis is measured or corrected by performing correction by the phase angle error Δψ and then measuring or calculating the eccentricity R from the rotation axis of the origin O.

Further, the thirteenth means is the sliding mechanism parameter of the one of the tenth to twelfth means, which is required when the V block is exchanged, repaired or adjusted, and is related to the posture of the V block sliding means. at least one of the correction values, by providing the sliding mechanism parameter automatic correction means for performing automatically based on the measurement values of radius a _m and center coordinates motion parameters during the central axis positioning of the gauge cylinder is known ξ is there.

  In addition, the fourteenth means includes the cylindrical axis positioning device of any one of the tenth to thirteenth means in the roundness measurement apparatus of any one of the first to ninth means. It is.

  Further, the fifteenth means is a cylindrical grinder for grinding a cylinder eccentric from the rotation axis using the synchronous control means, or the roundness measuring device of any one of the first to ninth means, or By providing at least one of the cylindrical axis positioning devices of any one of the tenth to thirteenth means, and synchronously controlling the relative position x and the rotation angle ψ by the function x (ψ). is there.

  Further, the sixteenth means is the above-described fifteenth means, wherein the roundness measuring device according to any one of the first to ninth means and any one of the tenth to thirteenth means. A cylindrical axis positioning device, which combines the measurement or correction of the position coordinate of the origin O by the origin positioning means, the calculation of the roundness of the cylinder by the roundness calculating means, and the grinding process using the synchronous control means In this way, the eccentric cylinder is sequentially asymptotically processed into a perfect circle by sequentially executing the necessary number of times.

  If the origin positioning means or the cylindrical axis positioning device is used, the position of the axis of the eccentric cylinder can be accurately measured by detecting the motion parameter ξ of the mechanical motion of the V block sliding means or the like. It is possible to manufacture an eccentric cylinder with an accurate amount of eccentricity with respect to the rotating shaft and an accurate phase with respect to the rotating shaft, regardless of whether or not the degree measurement or the highly accurate round processing is performed.

  Therefore, if the origin positioning means or the cylindrical axis positioning device is used, for example, when processing the crankpin of the crankshaft of a multi-cylinder engine, the position of each crankpin with respect to the crank journal can be formed very accurately. For this reason, for example, the compression ratio of the ignited gas can be made uniform for each cylinder and the ignition phase for each cylinder can be optimized with extremely high accuracy, and thus fuel consumption, noise, vibration, etc. can be sufficiently suppressed. It is possible to manufacture a high performance engine.

  It can be applied to machining of workpieces such as eccentric cylinders such as crankshafts.

The side view which shows the general appearance of the cylindrical grinding machine 100 concerning the Example of this invention. The figure which shows the effect | action of the variable conversion means concerning the Example of this invention. Sectional view showing the positional relationship between the time of riding V gauge cylinder having a true circle cross-section of radius a _0. The block diagram of the cylindrical grinding machine 100 concerning the Example of this invention. The figure which shows how to obtain | require correction amount (delta) x (x, (psi)) concerning the Example of this invention. The typical sectional view of cylindrical grinding machine 200 which has the rotation angle sensor (rotary encoder RE) concerning the 2nd example of the present invention. The general flowchart of the measurement main program A0 which controls the cylindrical grinding machine 200. The flowchart of the phase angle error calculation subroutine B0 called from the measurement main program A0. The flowchart of the eccentricity calculation subroutine C0 called from the measurement main program A0. The typical side view (a) and front view (b) of the three-point contact type measuring device 700 concerning 3rd Example of this invention. The table | surface which shows the expansion rate with respect to each spectrum component of the perfect circle error of the three-point contact type measuring device 700. The typical front view (a) of the three-point contact type measuring device 800 concerning 4th Example of this invention, and the alternative block diagram (b) of the part. The table | surface which shows the expansion rate with respect to each spectrum component of the perfect circle error of the three-point contact measuring device 800. The figure which shows the roundness measuring method using the horse riding gauge type | formula three-point contact method. The figure which shows the roundness measuring method using the horse riding gauge type | formula three-point contact method. The table | surface which shows the expansion rate with respect to each spectrum component of a perfect circle error at the time of using a horse riding gauge.

Explanation of symbols

C ... C axis (workpiece rotation axis)
K ... Cylindrical workpiece (circumferential cross section)
P ... 1st pivot P '... 2nd pivot W ... Grinding wheel rotating shaft 1 ... 1st arm 21 ... 2nd arm upper arm 22 ... 2nd arm lower arm 7 ... Grinding wheel 8 ... Output line of three-point contact type measuring instrument 9 ... Wheelhead 10 ... Numerical control device 14,
15 ... Sine wave signal branching device 16,
17 ... Wave shaper 25 ... V gauge or horse riding gauge of a three-point contact type measuring instrument 27 ... Measuring element 100 of a three-point contact type measuring instrument ... Cylindrical grinding machine (first embodiment)
200 ... Cylindrical grinding machine (second embodiment)
RE ... Rotary encoder A0 ... Measurement main program B0 ... Phase angle error calculation subroutine C0 ... Eccentricity calculation subroutine 700 ... Three-point contact type measuring instrument (third embodiment)
29 ... V block vertical movement actuator 800 ... Three-point contact measuring instrument (fourth embodiment)

Claims (21)

In a roundness measuring apparatus for measuring the roundness of the cylinder eccentric from the rotation axis in a state where a workpiece having a cylinder rotating eccentric from the rotation axis is attached to a grinder in a grindable state,
A first pivot pivotably provided on the grinding wheel platform;
A first arm supported at the first pivot and rotatably provided at one end;
A second pivot that is pivotally provided at the other end of the first arm;
At one end, a second arm upper arm supported by the second pivot and rotatably provided;
A second arm lower arm provided on the second arm upper arm;
A three-point contact measuring instrument that is provided on the lower arm of the second arm and slides on the outer peripheral surface in contact with the outer peripheral surface of the cylinder, and measures the radius of the cylinder by a three-point contact method. Roundness measuring device. In a roundness measuring apparatus for measuring the roundness of the cylinder eccentric from the rotation axis in a state where a workpiece having a cylinder rotating eccentric from the rotation axis is attached to a grinder in a grindable state,
A measuring instrument for measuring the diameter of the cylinder in contact with the outer peripheral surface of the cylinder;
A measuring instrument sliding means for moving the measuring instrument in contact with the outer peripheral surface of the cylinder along a rotation locus around the rotation axis of the cylinder;
Detecting means for rotating the rotating shaft and detecting an output value of the measuring device at a constant time period;
A roundness measuring device comprising: a roundness calculating means for calculating the roundness of the cylinder from the output value. In a roundness measuring apparatus for measuring the roundness of the cylinder eccentric from the rotation axis in a state where a workpiece having a cylinder rotating eccentric from the rotation axis is attached to a grinder in a grindable state,
A measuring instrument for measuring the diameter of the cylinder in contact with the outer peripheral surface of the cylinder;
A measuring instrument sliding means for moving the measuring instrument in contact with the outer peripheral surface of the cylinder along a rotation locus around the rotation axis of the cylinder;
Detecting means for rotating the rotating shaft and detecting an output value of the measuring device at every fixed rotation angle of the rotating shaft;
A roundness measuring device comprising: a roundness calculating means for calculating the roundness of the cylinder from the output value.   The roundness measuring device according to claim 2, further comprising an average radius calculating unit that calculates an average radius of the cylinder from an average value of the output values.   4. The roundness measurement unit according to claim 2, further comprising a radius distribution calculating unit that obtains a Fourier coefficient of the output value and obtains a radius distribution related to a rotation angle of the radius of the cylinder from the Fourier coefficient. apparatus.   A Fourier coefficient of the output value is obtained, a radius distribution relating to the rotation angle of the cylinder radius is obtained from the Fourier coefficient, and a true circle error distribution relating to the rotation angle of the true circle error is obtained from a difference between the radius distribution and a reference radius. 4. The roundness measuring apparatus according to claim 2, further comprising a circle error distribution calculating unit.   6. The perfect circle according to claim 5, further comprising: a feed amount correcting unit that corrects a feed amount distribution of the grindstone related to a rotation angle of the rotating shaft based on the radius distribution obtained by the radius distribution calculating unit. Degree measuring device.   The feed rate correction means for correcting the feed rate distribution of the grindstone related to the rotation angle of the rotary shaft based on the true circle error distribution obtained by the true circle error distribution calculation means. The roundness measuring device described. In a roundness measuring apparatus for measuring the roundness of the cylinder eccentric from the rotation axis in a state where a workpiece having a cylinder rotating eccentric from the rotation axis is attached to a grinder in a grindable state,
A measuring instrument for measuring the diameter of the cylinder in contact with the outer peripheral surface of the cylinder;
A measuring instrument sliding means for moving the measuring instrument in contact with the outer peripheral surface of the cylinder along a rotation locus around the rotation axis of the cylinder;
Detecting means for rotating the rotating shaft and detecting an output value of the measuring device;
A radius distribution calculating means for obtaining a Fourier coefficient of the output value detected by the detecting means and obtaining a radius distribution relating to a rotation angle of the radius of the cylinder from the Fourier coefficient;
A roundness measuring apparatus comprising: a feed amount correcting unit that corrects a feed amount distribution of a grindstone related to a rotation angle of the rotating shaft based on the radius distribution obtained by the radius distribution calculating unit. In a roundness measuring apparatus for measuring the roundness of the cylinder eccentric from the rotation axis in a state where a workpiece having a cylinder rotating eccentric from the rotation axis is attached to a grinder in a grindable state,
A measuring instrument for measuring the diameter of the cylinder in contact with the outer peripheral surface of the cylinder;
A measuring instrument sliding means for moving the measuring instrument in contact with the outer peripheral surface of the cylinder along a rotation locus around the rotation axis of the cylinder;
Detecting means for rotating the rotating shaft and detecting an output value of the measuring device;
A Fourier coefficient of the output value detected by the detection means is obtained, a radius distribution relating to a rotation angle of the radius of the cylinder is obtained from the Fourier coefficient, and a rotation angle of a perfect circle error is obtained from a difference between the radius distribution and a reference radius. A circular error distribution calculating means for calculating a circular error distribution;
Roundness, characterized by comprising: a feed amount correcting means for correcting the feed amount distribution of the grindstone related to the rotation angle of the rotating shaft based on the true circle error distribution obtained by the true circle error distribution calculating means. measuring device.   The said measuring device is a three-point contact type measuring device which contacts the outer peripheral surface of the said cylinder, and measures the radius of the said cylinder by a three-point contact method. The roundness measuring device according to item.   The measuring device is a three-point contact type measuring device that contacts the outer peripheral surface of the cylinder and measures the radius of the cylinder by a three-point contact method, and the radius distribution is the three-point contact type measurement of the Fourier coefficient. 11. The true distribution according to claim 5, wherein the radius distribution is a radial distribution related to a rotation angle of the radius of the cylinder, which is corrected by an enlargement factor by a vessel and obtained from a corrected Fourier coefficient. Circularity measuring device. Detecting means for rotating the rotating shaft and detecting the output value of the three-point contact measuring instrument at a constant time period;
The roundness measuring device according to claim 1, further comprising: a roundness calculating unit that calculates the roundness of the cylinder from the output value. Detecting means for rotating the rotating shaft and detecting an output value of the three-point contact measuring device for each fixed rotation angle of the rotating shaft;
The roundness measuring device according to claim 1, further comprising: a roundness calculating unit that calculates the roundness of the cylinder from the output value.   The roundness measuring device according to claim 13 or 14, further comprising an average radius calculating means for calculating an average radius of the cylinder from an average value of the output values.   The roundness measurement unit according to claim 13 or 14, further comprising a radius distribution calculating unit that obtains a Fourier coefficient of the output value and obtains a radius distribution related to a rotation angle of the radius of the cylinder from the Fourier coefficient. apparatus.   A Fourier coefficient of the output value is obtained, a radius distribution relating to the rotation angle of the cylinder radius is obtained from the Fourier coefficient, and a true circle error distribution relating to the rotation angle of the true circle error is obtained from a difference between the radius distribution and a reference radius. The roundness measuring apparatus according to claim 13 or 14, further comprising a circle error distribution calculating unit.   The true amount according to claim 16, further comprising: a feed amount correcting means for correcting a feed amount distribution of the grindstone related to a rotation angle of the rotating shaft based on the radius distribution obtained by the radius distribution calculating means. Circularity measuring device.   The feed amount correcting means for correcting the feed amount distribution of the grindstone related to the rotation angle of the rotating shaft based on the true circle error distribution obtained by the true circle error distribution calculating means. The roundness measuring device described.   The radius distribution is a radius distribution related to a rotation angle of a radius of the cylinder obtained by correcting the Fourier coefficient with an enlargement ratio by the three-point contact measuring device and obtaining the corrected Fourier coefficient. Item 20. The roundness measuring apparatus according to any one of Items 16 to 19.   A cylindrical grinder having the roundness measuring device according to any one of claims 1 to 20.

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