JP6248887B2 - Apparatus and method for measuring thread shape of threaded member having hook-like flank - Google Patents

Description

  The present invention relates to a threaded member having a hook-like flank portion, which is used for measuring a thread shape of a threaded member having a hook-like flank portion among various threaded members including an oil well pipe threaded joint. The present invention relates to a screw shape measuring apparatus and method.

  The hook-shaped flank portion refers to a thread flank surface (a flank surface to which a load is applied with respect to an axial tensile force) in the screw portion, and approaches the screw thread center portion from the tip end portion to the base end portion ( A threaded portion that is in an overhang state from the base end to the tip of the thread.

The measurement of the screw shape is to obtain a screw shape profile in the screw axis direction, and the screw element is measured based on the screw shape profile. For example, in the case of an oil well pipe screw, the screw element includes the following items.
Stand-off: The dimension in the tube axis direction of the fitting portion between the male screw provided on the pipe and the female screw provided on the joint.
Thread diameter: The diameter of the thread bottom at the reference distance position from the pipe end (dimension in the pipe radial direction), and the difference between this diameter and the nominal diameter (diameter in the drawing) is a standoff deviation.
-Nose outer diameter: The outer diameter of the pipe end parallel part.
Screw lead: A travel distance in the screw axis direction per screw rotation (= screw pitch × number of threads).
-Screw taper: The amount of change in screw radius per unit length in the screw axis direction.
-Screw height: It is the dimension in the screw radial direction from the screw bottom to the screw top.
Thread width: The thread axial dimension of the thread valley at the midpoint between the thread bottom and the thread top.

Conventional thread-shaped measurement techniques for various threaded members including oil well pipe threaded joints include the following.
(C1) Prior art C1 is a method and apparatus for measuring a screw element by irradiating parallel light, detecting light passing through the screw surface, and scanning an optical sensor that measures the screw shape in the tube axis direction. (See Patent Document 1).
(C2) The conventional technique C2 sequentially detects a one-dimensional image with respect to the screw tube radial direction through parallel-light through an angle-variable reflecting mirror, an f-θ lens in which the relationship between the image receiving axis and the angle of view is proportional, A screw shape measuring method and apparatus characterized by generating a two-dimensional image (see Patent Document 2). If the optical system is rotated in the tube circumferential direction, three-dimensional screw shape measurement is also possible.
(C3) Prior art C3 irradiates parallel light toward the threaded portion of the threaded tube, scans the optical sensor for measuring the thread shape in the tube axis direction, and does not involve the measurement of the screw flank surface. It is equipped with an optical sensor that measures elements and a contact probe that can move three-dimensionally. The contact probe is brought into contact with the screw flank surface, and the spatial coordinates of the contact probe at the time of contact are detected, thereby measuring the screw flank surface. A contact-type sensor for measuring the second screw element involved, and an arithmetic processing means for calculating the screw element by synthesizing the first screw element obtained from the optical sensor and the second screw element obtained from the contact-type sensor A screw element measuring method and apparatus (see Patent Document 3). Thereby, the shape of a screw having a hook shape can be measured.
(C4) Prior art C4 uses a screw shaft detection step for detecting a screw shaft, a light source that emits a slit-shaped laser beam, and an imaging unit having a visual axis in a direction different from the optical axis of the light source. This is a method (optical cutting method) for obtaining the hook shape in a non-contact manner (see Patent Document 4).

Japanese Patent No. 3552440 Japanese Patent No. 5251617 Japanese Patent No. 4486700 Japanese Patent No. 5288297

  In the measurement principle (prior art C1 and C2) in which the parallel light is irradiated onto the screw, even if the parallel light is irradiated in the tangential direction of the screw spiral as shown in FIG. 10A, the parallel optical path is linear and spiral. Therefore, as shown in FIG. 10 (b), the screw-shaped profile captured by parallel light has a cross-sectional area of the hook-shaped flank portion that overlaps from the rear side to the front side in the screw depth direction. The profile is different from the actual one. Therefore, it is impossible to measure a screw shape having hook-like flank portions (particularly, screw width and lead).

  In order to solve such a problem, a hook-shaped flank portion that cannot be measured with parallel light is measured with a contact probe and superimposed with the profile of another portion that can be measured with parallel light (prior art C3). A method (prior art C4) using a light cutting method in which a flank portion is inclined to an angle suitable for flank surface angle measurement has been proposed.

  However, in the method such as the prior art C3, since the contact type probe is sequentially moved and the spherical contact attached to the tip is brought into contact with the flank surface, the measurement time is inevitably increased. There is a problem that the angle of the flank surface cannot be measured with high accuracy because the number of measurement points cannot be obtained sufficiently. In addition, there is a problem that the product is wrinkled by contact with the contact. Moreover, since the contact has a predetermined dimension, it is difficult to accurately measure the curvature of the curved surface portion of the screw bottom.

  In addition, the method such as the prior art C4 solves the problem of the contact type by using the light cutting method (two-dimensional triangular distance measuring method) which is a non-contact measurement method. Is very large, exceeding ± 0.04 mm, and it is difficult to measure a threaded member that has a thread dimension tolerance within ± 0.04 mm. (A) It takes time to measure over the entire length of the screw. There was a problem such as this.

  Note that the calculation error of the light cutting method (two-dimensional triangulation method) is large because the size variation range of the detection element array is 0.01 to 0.05 mm and the influence of multiple reflection of laser light. It is presumed to be due to value leakage due to removal of the measured value (noise).

  Therefore, in view of the problems (a) and (b) of the prior art described above, the present invention has a measurement accuracy within ± 0.02 mm evaluated by the difference between the design value of the screw shape having the hook-shaped flank portion and the measured value. It is an object of the present invention to provide a screw shape measuring apparatus and method capable of easily and efficiently performing precise measurement over the entire length of the screw portion.

  The present inventors have intensively studied to solve the above problems, and as a result, not using the light cutting method (two-dimensional triangulation method) but using a laser displacement meter of the one-dimensional triangulation method. Therefore, the calculation error can be improved to within ± 0.02 mm, the time required for measurement over the entire screw length can be shortened, and the measurement value (noise) affected by the multiple reflection of laser light and the influence of multiple reflection of light The present inventors have found that it is possible to more accurately distinguish a measured value (signal) that is not present, and to reduce value leakage due to noise removal.

The present invention has been made based on the above-mentioned findings, and the gist thereof is as follows.
(1) An apparatus for measuring the thread shape of a threaded member having a hook-like flank portion,
One one-dimensional triangulation system laser displacement meter moves on the axis of each of one or more support shafts, and the screw of the threaded member has a light beam tilt angle of 90 ° ± 10 ° from the axis. A first optical means configured to scan the part and acquire primary profile information of the screw part;
Another one-dimensional triangulation laser displacement meter moves on the same axis of the same spindle as the first optical means, and scans the threaded portion with a light beam tilt angle of 50 ° ± 10 ° from the axis. A second optical means configured to acquire primary profile information of the thread portion;
A screw shaft searching means for optically searching for a screw axis;
Centering means for aligning the defined plane of the light beam tilt angle from the axis of the spindle with the searched screw axis;
Tip position detecting means for optically acquiring tip position information of the threaded member;
The irradiation light of the laser displacement meter of the second optical means is subjected to multiple reflection at the screw portion, thereby removing the multiple reflected light peak detected by the image sensor of the laser displacement meter, and 1 from the second optical means. Signal processing means for generating secondary profile information from the next profile information;
Primary profile information acquired by the first optical means, secondary profile information generated by signal processing of the primary profile information acquired by the second optical means by the signal processing means, and the tip position detection A screw element measuring means for calculating a screw element based on pipe end position information acquired by the means, and a thread shape measuring device for a threaded member having a hook-like flank portion.
(2) The screw element calculation means includes:
The primary profile information by the first optical means and the secondary profile information by the second optical means and the signal processing means are corrected based on the light beam inclination angles of the first and second optical means, respectively. First calculating means for generating profile information after correction;
Based on the corrected profile information generated by the first calculation means, second calculation means for generating overall profile information;
The screw shape measuring device for a threaded member having a hook-like flank portion according to (1), further comprising: a third calculation means for calculating a screw element from the overall profile information.
(3) A method for measuring the screw shape of a threaded member having a hook-like flank using the screw shape measuring device according to (1),
A step of optically searching for a screw axis by the screw shaft searching means;
Aligning the definition plane of the light beam inclination angle from the axis of the spindle with the centering means to the searched screw axis;
Obtaining tip position information of the screw member by the tip position detecting means;
Obtaining the primary profile information with the first and second optical means;
Generating the secondary profile information from the primary profile information from the second optical means in the signal processing means;
A screw element having a hook-like flank portion, the screw element calculating means calculating a screw element based on the acquired primary profile information and the generated secondary profile information. Shape measurement method.
(4) The step of calculating the screw element by the screw element calculation means includes:
The primary profile information by the first optical means and the secondary profile information by the second optical means and the signal processing means are corrected based on the light beam inclination angles of the first and second optical means, respectively. A first calculation step for generating corrected profile information;
A second calculation step of generating overall profile information based on the corrected profile information generated in the first calculation step;
The screw shape measuring method for a threaded member having a hook-like flank as described in (3) above, further comprising a third calculation step of calculating a screw element from the overall profile information.

  According to the present invention, there is an excellent effect that precise measurement of the thread shape of a threaded member having a hook-shaped flank portion can be easily and quickly performed over the entire length of the thread portion.

It is the schematic which shows an example of the screw shape measuring apparatus which concerns on this invention. It is a schematic diagram which shows the measurement principle of the laser displacement meter of a one-dimensional triangulation system. It is a schematic diagram of the cross section in the screw axis direction showing the configuration of the first optical means. It is a schematic diagram of the cross section in the screw axis direction showing the configuration of the second optical means. It is a pipe front view showing an example of composition of a screw axis search means. It is explanatory drawing of the signal processing logic which removes a multiple reflected light peak. It is explanatory drawing of the profile information after correction | amendment. It is explanatory drawing of the pre-processing process of a 2nd calculation process. It is explanatory drawing of the coupling | bonding process among the 2nd calculation processes. It is a schematic diagram which shows the problem of prior art (C1) and (C2).

  FIG. 1 is a schematic view showing an example of a screw shape measuring apparatus according to the present invention. FIG. 1 is a side view of a pipe when the threaded member is a pipe. In FIG. 1, 1 is a tube (threaded member), 1A is a threaded portion, 2 is a support shaft, 2A is an axis, 3 is first optical means, 4 is second optical means, 5 is screw shaft search means, 6 is a centering means, 7 is a tip position detecting means, 8 is a signal processing means, 9 is a screw element calculating means, and 10 is a laser displacement meter (specifically, a laser displacement meter of a one-dimensional triangulation system).

  FIG. 2 is an explanatory diagram showing the measurement principle of the laser displacement meter 10. The laser displacement meter 10 condenses the laser light emitted from the light source 11 with the light projecting lens 12 and irradiates the measurement target, and a part of the diffuse reflection light from the measurement target passes through the light receiving lens 13 and the imaging element 14. The light spot (the point where the amount of received light is maximized) is connected to the top. Each time the measurement object (or laser displacement meter 10) moves, the light spot on the image sensor 14 also moves, so that the amount of displacement of the measurement object relative to the laser displacement meter 10 can be known. The displacement can be measured in units of 0.001 mm. Of the two measurement points, the side closer to the light source 11 is called the NEAR side, and the far side is called the FAR side. The amount of displacement corresponds to the distance from the light source 11 to the measurement object.

  If only one laser displacement meter 10 is used per one spindle 2, the primary profile of both the hook-like flank portion in the screw portion and the screw portion other than the hook-like flank portion (also referred to as a non-hook-like flank portion). It is difficult to obtain information with high accuracy at the same time. Therefore, in the present invention, two laser displacement meters 10 are used per one spindle 2, one of which is a component of the first optical means 3 and the other is a component of the second optical means 4. And 3 and 4 are schematic views of the cross section in the screw axis direction showing the configurations of the first optical means 3 and the second optical means 4, respectively. As shown in FIGS. 1 and 3, the first optical means 3 has a laser displacement meter 10 that moves on an axis 2A of one support shaft 2, and a light beam tilt angle θ1 = 90 ° ± 10 ° from the axis 2A. (One angle value selected from the range of 80 ° to 100 °, which is not changed during measurement), and scans the threaded portion 1A of the tube 1 to obtain primary profile information of the threaded portion 1A. . Thereby, primary profile information of a screw portion (non-hook-like flank portion) other than the hook-like flank portion is obtained. Since the irradiation light does not reach the hook-shaped flank portion, primary profile information of the hook-shaped flank portion cannot be obtained.

  On the other hand, as shown in FIGS. 1 and 4, the second optical means 4 is configured such that the laser displacement meter 10 moves on the axis 2 </ b> A of the same support shaft 2 as the first optical means 3, and the light beam tilts from the axis 2 </ b> A. The primary profile information of the screw portion 1A by scanning the screw portion 1A at an angle θ2 = 50 ° ± 10 ° (one angle value selected from the range of 40 ° to 60 °, which is not changed during measurement). It was set as the structure which acquires.

  The moving distance of the laser displacement meter 10 can be controlled in units of 0.001 mm.

  Thereby, it becomes easy to acquire the primary profile information of the non-hook-like flank portion and the hook-like flank portion at the same time with high accuracy. When the light beam inclination angle θ1 of the first optical means 3 is out of 90 ° ± 10 °, it is difficult to acquire the primary profile information of the non-hook-like flank portion with high accuracy. On the other hand, if the light beam inclination angle θ2 of the second optical means 4 is out of 50 ° ± 10 °, it is difficult to obtain the primary profile information of the hook-shaped flank portion with high accuracy.

  Further, in this example, the support shafts 2 of the first and second optical means 3 and 4 are respectively provided at four locations on the circumference of the circle surrounding the tube 1 so that four locations in the tube circumferential direction can be measured simultaneously. There are a total of four. However, it is not necessarily limited to these four.

  The central axis of the circle surrounding the tube 1 is taken as the X axis. The X axis is parallel to each support shaft 2.

  The four support shafts 2 are fixed to one support frame 30 so that the four positions can be changed in the same circumferential direction, and the support frame 30 is rotatable around the X axis.

  The respective light beam inclination angles of the first and second optical means 3 and 4 are defined within a common plane of each axis 2A and the X axis. That is, the common plane of each axis 2A and the X axis is a definition plane of the light ray inclination angle of each axis 2A.

  By the way, the screw element is calculated based on the profile information in the screw axial direction cross section. Therefore, the axis 2A and the light beam from the axis 2A need to be in the same screw axial section. Therefore, in the present invention, the screw shaft searching means 5 for optically searching for the screw axis and the centering means 6 for aligning the X axis with the searched screw axis are provided. Since the X axis is a straight line common to the definition planes of the respective light beam tilt angles, the definition plane of the respective light beam tilt angles can be aligned with the screw axis line by aligning the X axis with the screw axis line.

  As shown in FIG. 1, the screw shaft searching means 5 is installed at two locations in the longitudinal direction of the pipe. One of the two locations is a non-screw part on the screw tip side (for convenience, A part), and the one installed at the A part is the screw shaft search means 5A, and the other of the two parts is the screw base end. The non-screw part on the side (referred to as B part for the sake of convenience) and what is installed at the B part is referred to as screw shaft searching means 5B.

  As shown in FIG. 5, the screw shaft searching means 5 optically detects both ends of the pipe diameter in the y direction and the z direction, which are orthogonal to each other, as shown in FIG. An intersection C between the detected straight line connecting the pipe diameter end points P and Q and the straight line connecting the pipe diameter end points R and S detected in the z direction is identified as one point on the screw axis. Since points on the screw axis are identified at two locations in the longitudinal direction of the tube (A portion and B portion), two points on the screw axis are identified, and the screw axis can be searched.

  As means for optically detecting the tube diameter end point, FIG. 5 illustrates the light emitting / receiving end detector 20. This is because the parallel light 23 from the light projecting unit 21 is applied to the visual field region including the object end, and the transmitted light from the visual field is received by the light receiving unit 22 and imaged. The edge is detected. As shown in FIG. 5, a total of four such light emitting / receiving end detectors 20 are arranged so that two parallel lights 23 in the y direction and the z direction surround the tube 1 in a grid pattern, The axis search means 5A and 5B are configured.

  In FIG. 5, an area camera type end detector may be used instead of the light projecting / receiving type end detector 20. The configuration of the screw shaft searching means using the area camera type end detector is shown in FIG. 5 in which the four light projecting parts 21 and the light receiving part 22 are deleted, and the area camera is located at the four places where the light receiving part 22 is deleted. Are arranged so that the end of the tube diameter enters the field of view of the area camera.

  The centering means 6 is a means for making the X axis coincide with the screw axis identified by the screw axis searching means 5, and as shown in FIG. 1, the support frame 30 is arranged in the X axis direction and 2 perpendicular to the X axis. The mechanism includes a mechanism that moves in the axial direction, that is, the Y-axis direction and the Z-axis direction, and a mechanism that rotates around the Y-axis and Z-axis.

  The angle (angle error with respect to 0 °) formed by the X axis after the alignment by the centering means 6 and the screw axis is within 0.01 °.

  Therefore, by having the screw shaft search means 5 and the centering means 6, the light beam from the axis 2A and the light source on the axis 2A can be easily and accurately positioned in the cross section in the screw axis direction, and accurate primary profile information. Can be obtained.

  In addition, in order to obtain profile information of the entire screw portion based on the primary profile information obtained by the first and second optical means 3 and 4, the tip position information of the screw member (in this example, the tip of the tube) Position information) is required. Therefore, the tip position detecting means 7 is provided in the present invention. The tip position detection means 7 comprises a laser distance meter. This laser distance meter measures the distance to the tip of the tube 1 with a distance measuring laser beam oriented parallel to the X axis, and acquires the tip position information of the tube. The distance measurement starting point position is known with respect to the first and second optical means 3 and the respective standby positions. Therefore, using the acquired tube tip position information, the movement distance values of the first and second optical means 3 and 4 are converted into coordinate values in the X-axis direction with the tube tip position as the origin. Can do.

  Further, in the laser displacement meter 10 of the second optical means 4 that scans the hook-shaped flank portion with the light beam inclination angle θ2 = 50 ° ± 10 °, as shown in FIG. 6, only the diffuse reflected light used for obtaining the profile information is obtained. In addition, there may be a case where multiple reflected light formed by regular reflection on the side surface of the screw portion and then regular reflection on the bottom surface of the screw portion also enters the image sensor 14 and shows a peak of the amount of received light. In this case, two light receiving positions where the amount of received light reaches a peak appear in the image sensor 14. One of the two peaks is a multiple reflected light peak, and the light receiving position indicating the multiple reflected light peak does not correspond to a true measurement target point. Corresponding to the true measurement target point is a light receiving position indicating another peak of diffuse reflection light peak. Therefore, the multiple reflected light peak is removed, and the signal processing means 8 is provided in which the light receiving position of the remaining diffuse reflected light peak is the position of the measurement target point. Prior to this, as a result of examining the signal processing logic of the signal processing means 8, the light receiving position of the multiple reflected light peak (also referred to as the multiple reflected light peak position) and the light receiving position of the diffuse reflected light peak (also referred to as the diffuse reflected light peak position). As shown in FIG. 6, it is found that the multiple reflected light peak position is on the FAR side and the diffuse reflected light peak position is on the NEAR side as shown in FIG. Therefore, the signal processing means 8 executes the signal processing logic for removing the peak whose peak position is on the FAR side when two peaks of the received light amount appear at the light receiving position of the image sensor 14, and the second optical The secondary profile information may be generated from the primary profile information in the means.

  In the first optical means 3 having the light beam inclination angle θ1 = 90 ° ± 10 °, the multiple profile light does not enter the laser displacement meter 10, and therefore the primary profile information can be used as it is.

  Next, the screw element calculation means 9 in FIG. 1 will be described. The screw element calculation means 9 is a secondary profile generated by performing signal processing on the primary profile information acquired by the first optical means 3 and the primary profile information acquired by the second optical means 4 by the signal processing means 8. This is a means for calculating a screw element based on the information and the pipe end position information in the X-axis direction acquired by the tip position detecting means 7.

  The screw element calculation means 9 preferably has first, second, and third calculation means for executing first, second, and third calculation steps described below.

  Note that the derivation of the coordinate values in the X-axis direction of the first and second optical means 3 and 4 using the pipe end position information has been executed prior to the first calculation step.

  The first calculation process will be described.

  In the first calculation step, the primary profile information by the first optical means 3 and the secondary profile information by the second optical means 4 and the signal processing means 8 are respectively used as the first and second profiles. Are corrected based on the light beam inclination angles θ1 and θ2 of the optical means 3 and 4, and profile information after correction is generated.

The primary profile information relates to the first optical means, and is a coordinate value (denoted as X1) in the X-axis direction of the light source position with the tube tip position as the origin, and a distance measurement value (S1) from the light source position. The data are arranged in the order of measurement. This data, i sequence order, the i-th X1, S1 and respectively _X1 i, S1 _i, expressed as _(X1 i, S1 _i). The secondary profile information relates to the second optical means, and is a coordinate value in the X-axis direction (denoted as X2) of the light source position with the tube tip position as the origin, and a distance measurement value from the light source position. It consists of data in which a set (denoted as S2) is arranged in the order of measurement. This data, j the sequence order, the j-th X2, S2 and each _X2 j, S2 _j, expressed as _(X2 j, S2 _j).

  As shown in FIG. 7, the corrected profile information is profile information when the measurement target point is measured at a light beam tilt angle of 90 °, and is calculated for all i and j by the following equation. In addition, the symbol of the data after correction was assumed to have A added to the head of the symbol before correction.

AX1 _i = X1 _i −S1 _i × cos θ1
AS1 _i = S1 _i × sin θ1
AX2 _j = X2 _j −S2 _j × cos θ2
AS2 _j = S2 _j × sinθ2
Next, the second calculation process will be described.

In the second calculation step, the data (AX1 _i , AS1 _i ) of the first optical means, which is the corrected profile information generated in the first calculation step, and the data (AX2 _j , second optical means) The entire profile information is generated based on AS2 _j ).

  The second calculation step includes a pre-processing step for correcting a shift in distance measurement value due to a machine difference between the first and second optical means, and each of the first and second optical means after the pre-processing step. There is a joining process for joining data together.

First, in the preprocessing step, BS2 _j is calculated by the following equation for all j.

BS2 _j = AS2 _j -ΔS
Here, as shown in FIG. 8, ΔS is based on a representative value (denoted as DS 1) of the distance measurement value of the first optical system at the non-threaded portion on the screw tip side, and is a second value from this reference. The deviation of the representative value (denoted as DS2) of the distance measurement value of the optical system, that is, ΔS = DS2−DS1. DS1 and DS2 are calculated as follows, for example. That is, assuming that the design value of the length of the non-threaded portion on the screw tip side is L, the range of _i related to AX1 _i and the range of _j related to AS2 _j within the range of L / 3 to 2 × L / 3, respectively. The average value of AS1 _i for the obtained i range is calculated as DS1, while the average value of AS2 _j for the obtained _j range is calculated as DS2. The first optical means is used as a reference because the first optical means whose light incident angle to the non-threaded portion as the reference measurement object is closer to 0 ° is closer to the true value. It is because it shows.

Next, in the combining step, data (AX1 _i , AS1 _i ) and data (AX2 _j , BS2 _j ) are combined. The method of combination is that the area including the hook-like flank measurement value in the data (AX1 _i , AS1 _i ) is the replacement part, and the replacement part is the corresponding area in the data (AX2 _j , BS2 _j ). Shall be replaced. This replacement method will be described below with reference to FIG.
(A) First, a part to be replaced is determined (see FIG. 9A). The method of determination is that the difference between AS1 _{i of} adjacent _i among the data (AX1 _i , AS1 _i ) for all i is equal to or greater than a threshold value (for example, 1/2 of the design value of the thread height). The values m and m + 1 of i are obtained. Then, the data (AX1 _m , AS1 _m ) and (AX1 _{m + 1} , AS1 _{m + 1} ) are used as replacement parts. One such m is determined for each thread.
(B) Next, a replacement part is determined (see FIG. 9B). The determination method obtains data closest to the data (AX1 _m , AS1 _m ) and (AX1 _{m + 1} , AS1 _{m + 1} ) from the data (AX2 _j , BS2 _j ) for all j. It is assumed that the obtained data is j = p data (AX2 _p , BS2 _p ) for i = m and j = q data (AX2 _q , BS2 _q ) for i = m + 1. Data (AX2 _p , BS2 _p ) to (AX2 _q , BS2 _q ) from j = p to j = q are used as replacement parts. The number of data in the replacement part (= q−p + 1) is 10 or more.
(C) Finally, the part to be replaced is replaced with a replacement part (see FIG. 9C). At the time of this replacement, the data arrangement order that was the two series of i and j is unified to form the K series as shown. In addition, what is written as AX and AS is simplified and written as X and S, respectively. Further, the symbols X1 and X2 are unified to the symbol X, and the symbols S1 and S2 are unified to the symbol S. The data (X _K , S _K ) for all K thus obtained is the entire profile information. In addition, M related to K = M in the figure is added to m−1 by adding all the data numbers of the replacement parts for each of the replacements performed from i = 1 to i = m−1. It becomes the value.

  Next, the third calculation process will be described.

In the third calculation step, the screw element is calculated from the data (X _K , S _K ) which is the entire profile information. By the way, the screw element includes a screw shape item related to the screw radial dimension (see the above definition), but the data (X _K , S _K ) does not include the screw radial dimension information. Therefore, the data (X _K , S _K ) is converted into data (X _K , r _K ) including thread radial direction dimension information. Here, r _K is the distance from the X axis (which has been aligned with the screw axis) to the measurement target point on the outer surface of the threaded portion. On the other hand, S _K is the distance to the same measurement object point from the axis 2A of the shaft 2, (referred to as R) the distance from the axis 2A of the shaft 2 to the X-axis is known. Therefore, r _K = R−S _K , and the data (X _K , r _K ) includes the screw radial dimension. That is, the data over all K (X _K , r _K ) is the entire profile information including the screw radial direction dimension information. By using this, the data necessary for calculating the screw shape item can be easily extracted. The screw element can be easily calculated.

A preferred measuring method using the screw shape measuring apparatus according to the present invention is as follows.
(i) The screw axis search means optically searches for the screw axis.
(ii) The centering means aligns the definition plane of the light beam tilt angle from the axis of the support shaft with the searched screw axis.
(iii) The primary profile information is acquired by the first and second optical means.
(iv) The secondary profile information is generated from the primary profile information from the second optical means by the signal processing means.
(v) A screw element is calculated by the screw element calculation means based on the acquired primary profile information and the generated secondary profile information.

  In the step of calculating the screw element by the screw element calculation means, it is preferable to execute the first, second, and third calculation steps in this order.

  The screw shape measuring apparatus according to the present invention is used in the screw shape inspection step in the embodiment shown in FIG. 1 and 100 thread shape measurements of the pin thread portion of the threaded joint for oil well pipes are performed to obtain an example of the present invention. The pin screw portion is a taper screw, and the load flank portion is a hook-like flank portion. Moreover, 100 thread shape measurements of the same pin screw part were performed by the method of the above-mentioned prior art (C4), and it was set as a comparative example. As the laser displacement meter 10, KEYENCE: LK-G30 (registered trademark) was used.

  As a result, in the case where the total length is simultaneously measured at four locations in the circumferential direction of the pin screw portion, the time required per one from the start of measurement to the calculation of the screw element is the comparative example in the present invention example. About 30% shorter.

  Further, the range of the difference between the design value of the screw width and the measured value was within ± 0.04 mm in the comparative example, but was not within ± 0.02 mm and was insufficient measurement accuracy. It was within ± 0.02 mm, and the measurement accuracy was sufficient.

1 Tube (threaded member)
DESCRIPTION OF SYMBOLS 1A Screw part 2 Support axis 2A Axis 3 1st optical means 4 2nd optical means 5 Screw axis search means 6 Centering means 7 Tip position detection means 8 Signal processing means 9 Screw element calculation means 10 Laser displacement meter 11 Light source 12 Throw Optical lens 13 Light receiving lens 14 Image sensor 20 End detector 21 Light projecting unit 22 Light receiving unit 23 Parallel light 30 Support frame

Claims (4)

An apparatus for measuring the thread shape of a threaded member having a hook-like flank portion,
One one-dimensional triangulation system laser displacement meter moves on the axis of each of one or more support shafts, and the screw of the threaded member has a light beam tilt angle of 90 ° ± 10 ° from the axis. A first optical means configured to scan the part and acquire primary profile information of the screw part;
Another one-dimensional triangulation laser displacement meter moves on the same axis of the same spindle as the first optical means, and scans the threaded portion with a light beam tilt angle of 50 ° ± 10 ° from the axis. A second optical means configured to acquire primary profile information of the thread portion;
A screw shaft searching means for optically searching for a screw axis;
Centering means for aligning the defined plane of the light beam tilt angle from the axis of the spindle with the searched screw axis;
Tip position detecting means for optically acquiring tip position information of the threaded member;
The irradiation light of the laser displacement meter of the second optical means is subjected to multiple reflection at the screw portion, thereby removing the multiple reflected light peak detected by the image sensor of the laser displacement meter, and 1 from the second optical means. Signal processing means for generating secondary profile information from the next profile information;
Primary profile information acquired by the first optical means, secondary profile information generated by signal processing of the primary profile information acquired by the second optical means by the signal processing means, and the tip position detection A screw element measuring means for calculating a screw element based on pipe end position information acquired by the means, and a thread shape measuring device for a threaded member having a hook-like flank portion. The screw element calculation means includes
The primary profile information by the first optical means and the secondary profile information by the second optical means and the signal processing means are corrected based on the light beam inclination angles of the first and second optical means, respectively. First calculating means for generating profile information after correction;
Based on the corrected profile information generated by the first calculation means, second calculation means for generating overall profile information;
3. The screw shape measuring device for a threaded member having a hook-like flank according to claim 1, further comprising a third computing unit that calculates a screw element from the overall profile information. A method for measuring a screw shape of a threaded member having a hook-like flank portion using the screw shape measuring device according to claim 1,
A step of optically searching for a screw axis by the screw shaft searching means;
Aligning the definition plane of the light beam inclination angle from the axis of the spindle with the centering means to the searched screw axis;
Obtaining tip position information of the screw member by the tip position detecting means;
Obtaining the primary profile information with the first and second optical means;
Generating the secondary profile information from the primary profile information from the second optical means in the signal processing means;
A screw element having a hook-like flank portion, the screw element calculating means calculating a screw element based on the acquired primary profile information and the generated secondary profile information. Shape measurement method. The step of calculating the screw element by the screw element calculation means includes:
The primary profile information by the first optical means and the secondary profile information by the second optical means and the signal processing means are corrected based on the light beam inclination angles of the first and second optical means, respectively. A first calculation step for generating corrected profile information;
A second calculation step of generating overall profile information based on the corrected profile information generated in the first calculation step;
The screw shape measuring method for a threaded member having a hook-like flank according to claim 3, further comprising a third calculation step of calculating a screw element from the overall profile information.

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