JP2001157951A - Shape accuracy measuring device by sequential two-point method and laser displacement meter interval measuring method for shape accuracy measurement by sequential two-point method - Google Patents

Abstract

(57) [Problem] To provide a laser displacement meter which can be easily used for measurement by a sequential two-point method. SOLUTION: Two laser displacement meters 4 and 5 are arranged on a table.
Displacement gauge holding member 3 that is aligned at regular intervals along the extension direction of the measurement line set for 1c, is held at an approximately equal distance from table 1c, and holds toward table 1c; The machine tool body 1a for moving the member 3 relative to the table 1c along the measurement line, and the positions of the laser beams from the laser displacement meters 4 and 5 applied to the table 1c are used for the relative movement of the displacement meter holding member 3. The position of the laser beam from the other laser displacement meter 5 coincides with the position of the laser beam from the other laser displacement meter 4 on the table 1c in accordance with the relative movement of the CCD 2 that is sequentially detected and the displacement meter holding member 3. The output of the two laser displacement meters 4 and 5 each time the displacement meter holding member 3 relatively moves by a distance equal to the distance between the two laser displacement meters 4 and 5 obtained from the relative movement amount of the displacement meter holding member 3 until the displacement. Faith Uptake, those comprising a control apparatus 1b by arithmetic processing based on those output signals sequentially two-point method determining the straightness error curve of the table 1c, and.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring shape accuracy such as straightness accuracy and plane accuracy of a machine tool or the like by a sequential two-point method. The present invention relates to a shape accuracy measuring device used. The present invention also relates to a method for determining the distance between two laser displacement meters as the distance between the displacement meters used in the sequential two-point method, in order to perform the shape accuracy measurement by the sequential two-point method using two laser displacement meters. It is.

[0002]

2. Description of the Related Art Conventionally, methods for measuring the straightness accuracy of a machine tool include a method using an autocollimator and a method using a laser interferometer. However, each of these methods has the following problems. .

A measuring method using an autocollimator is usually
This is a standard method used as an on-site measurement method for measuring a straightness error curve of a workpiece. In this method, the work of setting a mirror surface on the surface of the object to be measured, such as a workpiece, on which the straightness error curve is to be evaluated, aiming with a telescope, and measuring the tilt angle of the mirror surface is referred to as a measurement line (measurement line) This is repeated for a required measurement position along a line connecting the positions, and a straightness error curve is obtained by connecting the measured inclination angles. The problem is that the mirror surface is raised on a table with legs at two points along the measurement line, and the required slope is not strictly the slope just below the mirror surface. That is,
The inclination of the mirror surface means that the inclination between the two points where the legs are placed is determined, and includes an error at this point.

[0004] The measuring method using an autocollimator is as follows.
This involves setting the telescope, setting the reflector, and so on. Even in the measurement of straightness and the evaluation of flatness that requires repeated measurements, there is still room for errors in terms of workability. In fact, it is a measurement method that requires a large amount of time and requires time for work.

Further, when an autocollimator is used as a method for obtaining a straight motion error curve of a machine tool, a mirror surface is held by a holding device or the like on a tool table and fed, and the inclination of the mirror surface in the travel section of the tool table is reduced. A method of detecting the movement is conceivable. However, the movement of the tool stand is secondary if the inclination is generated according to the movement, and as the straightness error curve, the fluctuation in the direction perpendicular to the movement direction is first. It should be evaluated. Therefore, it is difficult to obtain a straight motion error curve on the machine tool side depending on the autocollimator.

[0006] On the other hand, the measurement method using a laser interferometer is in contrast to the measurement using an autocollimator, in which an interferometer is mounted on a machine tool, a laser is emitted from the laser oscillation device toward the interferometer, and the laser is emitted on the opposite side to the oscillation device. With a reflecting mirror, an error motion in the direction orthogonal to the laser beam accompanying the movement of the interferometer is detected. However, in order to obtain the straight shape error curve of the workpiece by this, it is necessary to smoothly move the interferometer attached to the workpiece along the measurement line (line connecting the measurement positions) along which the beam runs. To do so, there are many difficulties, including the difficulty in creating a device configuration for each object, and measurement is not actually possible. As a result, at present, the straight motion error curve of the machine tool is evaluated, and the accuracy of the workpiece is considered as being transferred to the workpiece. Since this is the case even when measuring one straightness error curve, it is practically impossible to measure the flatness of the workpiece by repeating this process.

[0007] Even when a straight-motion error curve on the machine side is obtained, there are restrictions on the following points. That is, in the measurement method using a laser interferometer, in a configuration in which a laser beam is split into two and directed toward a reflecting mirror, a beam spot moves in the reflecting mirror in accordance with the range in which the tool table moves, so that the motion error curve Is determined by the length that the laser beam can move in the reflecting mirror. Moreover, the measurement accuracy depends on the mirror processing accuracy of the reflecting mirror. Also, when the beam travels through space over long distances, it is susceptible to air disturbances, and the measurements fluctuate,
It becomes an error factor of the measurement result. Further, this method is also sensitive to minute vibrations of various parts of the machine on which the laser interferometer or the like is installed, and the accuracy of the repeated measurement is not as stable as the sequential two-point method described below.

In order to solve these problems, the present inventors have developed a sequential two-point method as a method for measuring the straightness accuracy of a machine tool. If you take a lathe as an example,
In the point method, two displacement meters are mounted on a tool stand at predetermined intervals in the feed direction of the tool stand. On the other hand, an appropriate measurement target such as a workpiece is arranged at the workpiece mounting position. Then, the feed of the tool table is repeated at a pitch equal to the mounting interval of the above-mentioned displacement meters, and the relative displacement between the tool table and the object to be measured is measured by the two displacement meters. As a result, two data trains based on the output of the displacement meter are obtained, and by processing them with a simple algorithm, the motion of the tool table and the straightness error curve of the workpiece or the like to be measured are simultaneously and independently obtained. Can be

Accordingly, the sequential two-point method does not require the use of a high-precision reference straight scale, and therefore the measurement range is not restricted by the length of the straight scale, but can be long, the rotation of the workpiece,
Measurement is possible even when vibration must be taken into consideration, such as motor drive, adjustment is easy, deployment to cylindricity, flatness, etc. is easy, measurement repeatability is good, function This is difficult to obtain with a conventional straight error curve measuring method such as an autocollimator, a laser interferometer, or the like. Strict comparison of the measurement results by each of the sequential two-point method and the autocollimator is difficult and has not yet been realized, but the characteristics of the sequential two-point method are clear and the accuracy of repeated measurement is good. Once the measuring device is set up on the machine and the operator is proficient, there is a high possibility that the sequential two-point measurement will establish itself as a standard.

As described above, the straightness of a machine tool or a workpiece is measured by a method using an autocollimator or a laser interferometer in general. To measure the movement of the machine and the workpiece at the same time, operate the machine paying attention to the mutual relationship, and change the tool to a tool holding device of MC (machining center) depending on the device configuration It is clear that the sequential two-point method is superior in terms of holding the measuring device and performing the accuracy measurement during the work process. The details of the sequential two-point method are described in “Straightness” published by the inventor of the present invention in “Research on Production”, Vol. 34, No. 6, pages 25-34, issued by the Institute of Industrial Science, The University of Tokyo in June 1982. Trends in Measurement Methods and Sequential 2
Point Method Development ”.

[0011]

By the way, when the principle of the sequential two-point method is confirmed, displacement meters of the capacitance type or the eddy current type have been used. Since the distance from the object to be measured cannot be increased and the operating distance range is small, it is necessary to take measures to avoid collision. Also, the eddy current type displacement meter had good performance and was easy to use, but when it was used for iron-based materials, it was affected by residual magnetism and was not practical. On the other hand,
With the recent development of sensor technology, a laser beam is irradiated to the measurement object and the laser beam reflected from the measurement object is received by the optical sensor, and the displacement amount of the measurement object is calculated based on the principle of triangulation from the movement amount of the light receiving position. A small laser displacement meter to be sought has been developed. According to such a laser displacement meter, the distance to the object to be measured and the operating distance range can be made large, so the above-mentioned problem is avoided and the two-point method is applied successively. It has become possible to do.

However, the laser displacement meter has a disadvantage that the spot diameter of the laser beam at the measurement point is as small as several tens of μm. That is, in the displacement type displacement meter of the capacitance type or the eddy current type, the diameter is about several mm to about 10 mm, and it is easy to determine the center position and sequentially configure the measurement device for the two-point method. Further, it could be considered that the measured value was detected as an average value for the above-mentioned diameter region. This may average the effect on the surface roughness of the machined surface as a result. On the other hand, in principle, the sequential two-point method requires that the position measured by one sensor is accurately measured by the other sensor with respect to the measurement points by two displacement meters.

In the case of a laser displacement meter, as a result of the small spot diameter at the measurement point as described above, it is susceptible to the influence of the surface roughness, and the fluctuation of the measured value due to the material to be measured and the state of the processed surface roughness is large. Therefore, it has been pointed out that the function as the displacement meter may not be achieved. In other words, for a material such as a casting, which has a complex property on the surface, the spot is specified by the property of diffuse reflection, and the measured value is more appropriately evaluated. It is shown that it is difficult to identify the spot position on the steel work surface seen in FIG. For this reason, as a result of configuring a device capable of performing the measurement based on the sequential two-point method with the laser displacement meter and attempting the measurement, the data measured repeatedly showed deterioration. In addition, since the spot diameter is small, a high-precision apparatus configuration and a lot of work are required to guarantee the relative positional relationship between the center position of the spot diameter and the apparatus body, and the principle of the two-point method must be satisfied sequentially. It is not easy to obtain data by moving the laser displacement meter in a predetermined positional relationship along the measurement line.

The present invention uses a laser displacement meter to sequentially perform two
The accuracy measurement device by the point method is constructed, and it is possible to measure the shape accuracy such as straightness and flatness of machine tools and three-dimensional measurement devices while avoiding the influence of surface roughness, material, etc. Accordingly, it is an object to increase the processing accuracy and the measurement accuracy while maintaining the processing efficiency and the measurement efficiency.

[0015]

In order to achieve the above object, the apparatus for measuring shape accuracy by the sequential two-point method according to the present invention is directed to an extending direction of a measuring line set for a measurement object of shape accuracy. A displacement meter holding member that aligns the two laser displacement meters along the line at a fixed interval, and holds the two laser displacement meters at approximately the same distance from the measurement target and holds toward the measurement target; and A holding member relative moving means for moving the meter holding member relative to the measurement object along the measurement line; and a displacement meter holding member for determining a position of the laser beam from the two laser displacement meters applied to the measurement object. An optical sensor for sequentially detecting the displacement sensor according to the relative movement of the laser displacement meter, and one of the two laser displacement meters in the measurement object according to the relative movement of the displacement meter holding member. The displacement meter by a distance equal to the distance between the two laser displacement meters obtained from the relative movement amount of the displacement meter holding member until the position of the laser beam from the other laser displacement meter matches the position of the laser beam. Each time the holding member moves relative to each other, the output signals of the two laser displacement meters are fetched, and the output signals are sequentially processed based on the two-point method to calculate a straightness error curve of the measurement object; It is characterized by having.

In such an apparatus, the displacement meter holding member aligns the two laser displacement meters at a fixed interval along the extending direction of the measurement line set for the shape accuracy measurement object, and aligns them. The two laser displacement meters are separated from the measurement target by substantially equal distances and held toward the measurement target, and a holding member relative moving unit moves the displacement meter holding member relative to the measurement target along the measurement line. Move,
The optical sensor sequentially detects the position of the laser beam from the two laser displacement meters irradiated to the measurement object with the relative movement of the displacement meter holding member, and the arithmetic processing means,
With the relative movement of the displacement meter holding member, the position of the laser beam from one of the two laser displacement meters of the two laser displacement meters in the measurement object matches the position of the laser beam from the other laser displacement meter. Each time the displacement meter holding member relatively moves by a distance equal to the distance between the two laser displacement meters determined from the relative movement amount of the displacement meter holding member up to, capturing the output signals of the two laser displacement meters, The output signals are successively calculated based on the two-point method to obtain a straightness error curve of the object to be measured, and output it.

Therefore, according to the apparatus of the present invention, when the displacement meter holding member is relatively moved with respect to the object to be measured, the positions of the laser beams having the small spot diameters of the two laser displacement meters are accurately matched, and the two laser Since relative displacement data for accuracy measurement by the two-point method can be obtained sequentially from the displacement meter, it is possible to prevent data deterioration due to repeated measurement and to determine the relative positional relationship between the spot diameter center position and the apparatus body. Data is obtained by moving the laser displacement meter along a measurement line in a predetermined positional relationship along the measurement line so as to satisfy the principle of the two-point method without requiring a high-precision device configuration or a lot of work to guarantee. be able to.

In the apparatus according to the present invention, the optical sensor is a one-dimensional or two-dimensional charge-coupled device (CC) fixed to the object to be measured directed to the laser displacement meter.
D), and the optical sensor may be a light-receiving surface two-division photoelectric conversion element or a light-receiving surface four-division photoelectric conversion element which is fixed to the object to be measured while facing the laser displacement meter. . If these CCDs and photoelectric conversion elements are used, the laser beam of the laser displacement meter can be detected accurately and at low cost. In particular, if a light-receiving surface four-division photoelectric conversion element is used, the laser spots of the two displacement meters and
Mutual displacement between the displacement gauge and a feed line extending in the direction in which the displacement gauges are sequentially sent can also be detected, so that the position of the displacement gauge can be easily adjusted.

In the apparatus according to the present invention, the optical sensor is an electronic camera (a light receiving element such as a two-dimensional CCD) fixed to a stationary portion of the holding member relative moving means so as to face the object to be measured. (A camera that captures an image of a distant object and outputs an image signal). According to such a configuration, the position of the optical sensor is fixed, so that the operability of the device is improved and the displacement meter for the measurement object is improved. It is possible to check the accuracy change of the device before and after use of the device and to periodically check the accuracy when using the device for a long period of time. The workability of the measurement work can be improved.

Further, in the apparatus of the present invention, the displacement meter holding member may have a laser displacement meter fine adjustment means for finely adjusting at least one of a relative position and an orientation of the two laser displacement meters. According to such a configuration,
The workability of the accuracy measurement work can be further improved.

In the apparatus of the present invention, the arithmetic processing means averages a plurality of output signals of each of the two laser displacement meters when the displacement meter holding member moves a plurality of times at minute intervals. The output signals of the two laser displacement meters for the arithmetic processing based on the sequential two-point method may be used. According to such a configuration, the processed surface roughness, the processed surface reflectance, the processed surface material, etc. To reduce the effect of
A point method can be applied.

In the apparatus for measuring shape accuracy by the sequential two-point method according to the present invention, two laser displacement gauges are arranged at regular intervals along a direction in which a measuring line set for a shape accuracy measurement object extends. And a displacement meter holding member that holds the two laser displacement meters at approximately the same distance from the measurement object and holds the two laser displacement meters toward the measurement object, and extends the measurement line with respect to the measurement object. Holding means for relative movement in the direction of alignment of the two laser displacement meters and relative movement in the direction of alignment of the two laser displacement meters, and holding of the position of the laser beam from the two laser displacement meters applied to the object to be measured. A two-dimensional optical sensor that sequentially detects the relative position of the member, and the measurement pair corresponding to the relative movement of the displacement meter holding member with respect to the measurement object along the measurement line. The laser beam from the other laser displacement meter is irradiated on the two-dimensional optical sensor from the position where the laser beam from one of the two laser displacement meters is irradiated on the two-dimensional optical sensor. The distance and alignment direction of the two laser displacement meters from the relative movement amount of the displacement meter holding member to the position to be performed, and the irradiation position of the laser beam from the two laser displacement meters on the two-dimensional optical sensor. The displacement meter holding member is moved relative to the measurement target by a distance equal to the distance between the two laser displacement meters with the relative movement of the displacement meter holding member in the alignment direction of the two laser displacement meters. Every time, the output signals of the two laser displacement meters are fetched, and the output signals are sequentially processed based on the two-point method to calculate the straightness error curve of the object to be measured. Means, may be characterized in that it comprises a.

In such an apparatus, the displacement meter holding member aligns the two laser displacement meters at regular intervals along the extending direction of the measurement line set with respect to the measurement object of the shape accuracy, and The two laser displacement meters are separated from the measurement target by an approximately equal distance and held toward the measurement target, and the holding member relative moving means firstly moves the displacement meter holding member to the measurement target along the measurement line. Relative displacement in the direction of alignment of the two laser displacement meters, and the two-dimensional optical sensor determines the position of the laser beam from the two laser displacement meters that irradiates the measurement object with the displacement meter. The detection is sequentially performed according to the relative movement of the holding member, and the arithmetic processing unit performs the second detection on the measurement object with the relative movement of the displacement meter holding member along the measurement line with respect to the measurement object. From the position where the laser beam from one of the laser displacement meters is irradiated onto the two-dimensional optical sensor to the position where the laser beam from the other laser displacement meter is irradiated onto the two-dimensional optical sensor From the relative movement amount of the displacement meter holding member up to and the irradiation position of the laser beam from the two laser displacement meters on the two-dimensional optical sensor, the interval and alignment direction of the two laser displacement meters are obtained. Every time the displacement meter holding member relatively moves in the direction of alignment of the determined two laser displacement meters by a distance equal to the determined distance between the two laser displacement meters, the output signal of the two laser displacement meters is determined. Then, the output signals are sequentially processed according to the two-point method to obtain a straightness error curve of the object to be measured and output.

Therefore, according to the apparatus of the present invention, when the displacement meter holding member is relatively moved with respect to the object to be measured, the positions of the laser beams having the small spot diameters of the two laser displacement meters are accurately matched, and the two laser Since relative displacement data for accuracy measurement by the two-point method can be obtained sequentially from the displacement meter, it is possible to prevent data deterioration due to repeated measurement and to determine the relative positional relationship between the spot diameter center position and the apparatus body. Data is obtained by moving the laser displacement meter along a measurement line in a predetermined positional relationship along the measurement line so as to satisfy the principle of the two-point method without requiring a high-precision device configuration or a lot of work to guarantee. be able to.

Further, according to the apparatus of the present invention, the displacement gauge holding member can be accurately and automatically moved in the direction in which the two laser displacement gauges are aligned. The shape accuracy measurement by the method can be easily performed.

In the above-described apparatus of the present invention and the above-described apparatus, the displacement meter holding member holds at least three laser displacement meters aligned in two directions perpendicular to each other. In this case, by selectively using two of the at least three laser displacement meters arranged in any one of two directions perpendicular to each other, a laser displacement meter or a displacement meter holding member can be used. The flatness can be measured without changing the flatness, and the flatness can be easily and automatically measured with high accuracy.

On the other hand, the above-described apparatus of the present invention and the above-described apparatus are arranged such that the displacement meter holding member is rotated by 90 ° to selectively align the two laser displacement meters in two directions perpendicular to each other. A member rotating means may be provided, and in this case, the displacement meter holding member is rotated by 90 ° by the holding member rotating means, and the two laser displacement meters are selected in one of two directions perpendicular to each other. The flatness can be measured without replacement of the laser displacement meter or the displacement meter holding member, and the flatness measurement can be easily performed automatically and with high accuracy.

Further, according to the laser displacement meter interval measuring method for shape accuracy measurement by the sequential two-point method of the present invention, the shape accuracy measurement by the sequential two-point method is performed by using two laser displacement meters. When obtaining the distance between the two laser displacement meters as the distance between the two laser displacement meters, the two laser displacement meters are aligned at regular intervals along the extending direction of the measurement line set for the measurement target of the shape accuracy. The two laser displacement meters are held at the same distance from the object to be measured and held toward the object to be measured, and the two laser displacement meters are attached to the object to be measured along the measurement line in the holding state. Relative movement, the position of the laser beam from the two laser displacement meters irradiated to the measurement object is sequentially detected by an optical sensor along with the relative movement, and the position is detected along with the relative movement. From the movement amount of the relative movement until the position of the laser beam from one of the two laser displacement meters of the two laser displacement meters in the measurement object coincides with the position of the laser beam from the other laser displacement meter. It is characterized in that an interval between two laser displacement meters is obtained.

According to this method, when the two laser displacement meters are relatively moved with respect to the object to be measured, the positions of the laser beams having small spot diameters of the two laser displacement meters are made to exactly coincide with each other, and the two laser displacement meters are moved. Since relative displacement data for accuracy measurement by the two-point method can be obtained from the meter sequentially, it is possible to prevent data deterioration due to repeated measurement and to guarantee the relative positional relationship between the spot diameter center position and the device body. To obtain data by moving the laser displacement meter along a measurement line in a predetermined positional relationship so as to satisfy the principle of the sequential two-point method without requiring a high-precision device configuration or a lot of work. Can be.

The laser displacement meter interval measuring method for measuring shape accuracy by the sequential two-point method of the present invention uses the two laser displacement meters to perform the shape accuracy measurement by the sequential two-point method. upon obtaining the interval between the two laser displacement meter as a displacement meter intervals used in law, at a certain distance the two laser displacement meter along schematically the extending direction of the measurement line set for measurement target shape accuracy The two laser displacement meters are held at the same distance from the object to be measured and held toward the object to be measured, and the two laser displacement meters are measured along the measurement line in the holding state. Move relative to the target, and sequentially detect the position of the laser beam from the two laser displacement meters irradiated to the measurement target with a two-dimensional optical sensor with the relative movement, the With the relative movement of the displacement meter holding member with respect to the fixed object along the measurement line, a laser beam from one of the two laser displacement meters of the measurement object on the two-dimensional optical sensor. The relative movement amount of the displacement meter holding member from the irradiation position to the position where the laser beam from the other laser displacement meter is irradiated onto the two-dimensional optical sensor, and the laser beam from the two laser displacement meters The distance between the two laser displacement meters may be obtained from the irradiation position on the two-dimensional optical sensor.

According to this method, when the two laser displacement meters are relatively moved with respect to the object to be measured, the positions of the laser beams having a small spot diameter of the two laser displacement meters are made to exactly coincide with each other, and the two laser displacement meters are displaced. Since relative displacement data for accuracy measurement by the two-point method can be obtained from the meter sequentially, it is possible to prevent data deterioration due to repeated measurement and to guarantee the relative positional relationship between the spot diameter center position and the device body. To obtain data by moving the laser displacement meter along a measurement line in a predetermined positional relationship so as to satisfy the principle of the sequential two-point method without requiring a high-precision device configuration or a lot of work. Can be.

In addition, according to this method, even if the initially set extending direction of the measurement line does not exactly match the alignment direction of the two laser displacement meters, the distance between the two laser displacement meters is accurately obtained. Therefore, the device can be mounted on a machine tool or the like, and the shape accuracy can be easily measured sequentially by the two-point method.

[0033]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Here, FIG. 1 shows a conventional NC (numerical control) machine tool (in the illustrated example, a portal type stand) so as to carry out an embodiment of a method of measuring a laser displacement gauge for measuring shape accuracy by a sequential two-point method of the present invention. FIG. 1 is a perspective view schematically showing an embodiment of a shape accuracy measuring apparatus according to the present invention, which is constituted by using a milling machine, and is a machine tool indicated by reference numeral 1 in the figure. And a control device 1b having an ordinary computer, wherein the machine tool main body 1a is a numerical control by the control device 1b, and in a three-dimensional rectangular coordinate system shown in FIG. In the direction (along the y-axis), the main shaft head 1e supported by the portal column 1d in the horizontal x-axis direction (the direction along the x-axis), and the main shaft (not shown) protruding from the lower end of the main shaft head 1e. In the vertical z-axis direction (along the z-axis). Direction).

In the shape accuracy measuring apparatus of this embodiment, the table on the table 1c of the machine tool main body 1a or its table 1c is used to obtain a straightness error curve in a vertical plane including the y-axis and the z-axis. A two-dimensional CCD 2 as an optical sensor is fixed upward on 1c.
2 is input to the control device 1b, while the displacement meter holding member 3 is fixed to the lower end of the ram protruding from the lower end of the spindle head 1e of the machine tool main body 1a. Two ordinary laser displacement gauges 4 and 5 are held at a predetermined position on a measurement line set to extend in the y-axis direction and are spaced apart from each other. 5 is also input to the control device 1b.

2 (a), 2 (b) and 2 (c) are a front view, a bottom view, and a cross-sectional view taken along line AA in the enlarged view of the displacement meter holding member 3. . In this embodiment, as shown in the figure, the displacement meter holding member 3 has four projections 3a to form a substantially H shape, and the four projections 3a have a guide hole 3b and a micrometer mounting hole, respectively. The guide rod 6 is slidably fitted into the guide hole 3b and the main body 7a of the micrometer 7 is fitted into the micrometer mounting hole 3c at two of the four projecting portions 3a. Are mounted, and their guide rods 6
The brackets 8 having a T-shaped cross section are fixed to each other, the tracing stylus 7b of the micrometer 7 is fixed to each of the brackets 8, and the laser displacement gauges 4 and 5 are attached to the brackets 8, respectively. In the drawings, reference numerals 4a and 5a indicate irradiation ports of the laser displacement meters 4 and 5, and B indicates a laser beam emitted from the irradiation ports 4a and 5a.

According to the displacement gauge holding member 3, up to four laser displacement gauges can be respectively held by the four projecting portions 3a. The shape accuracy measurement is performed along the measurement line in the y-axis direction, whereby the flatness measurement can be performed. In addition, the micrometer 7 is operated to guide each bracket 8 and thus each laser displacement meter 4 under the guidance of the guide rod 6. , 5 are moved in the direction indicated by the arrow C in the figure to finely adjust the distance between the laser displacement gauges 4 and 5 with respect to the measurement target, so that the distance between the two laser displacement gauges 4 and 5 with respect to the measurement target is easily adjusted. be able to. The displacement meter holding member 3
In addition to the above distance adjustment, the mounting angle of each of the laser displacement meters 4 and 5 to each bracket 8 is similarly changed by a micrometer or the like as shown by dotted arrows D and E in the figure. The postures of the laser displacement meters 4 and 5 and thus the irradiation direction of the laser beam may be finely adjusted. In this case, the workability of the accuracy measurement preparation work can be further improved.

In the shape accuracy measuring apparatus of this embodiment having such a configuration, first, before obtaining the straightness error curve by the two-point method, the controller 1b firstly sets the table 1c of the machine tool main body 1a to y. By appropriately moving the spindle head 1e and thus the displacement meter holding member 3 in the x-axis direction, the one laser displacement meter 4 is placed above the two-dimensional CCD 2.
And the laser displacement meter 4 is operated. As a result, the laser beam B of the laser displacement meter 4 is changed to a two-dimensional CC.
A certain position on D2 is irradiated.

FIG. 3 is a block diagram functionally showing a configuration for obtaining the distance between the two laser displacement gauges 4 and 5 from the output signal of the two-dimensional CCD 2 in the shape accuracy measuring apparatus of this embodiment. As in this embodiment, the control device
1b has a spot center position detecting section 1f and an operation control section 1g. According to an operation program given in advance, first, the spot center position detecting section 1f uses the laser beam B of the laser displacement meter 4 by the spot center position detecting section 1f. Two-dimensional CC at the center of laser beam spot 2a generated on two-dimensional CCD 2
The position (x, y coordinates) on D2 is represented by the two-dimensional CCD2
Detection based on the output signal of the
By moving the table 1c in the y-axis direction, the two-dimensional CCD 2 is positioned below the other laser displacement meter 5,
Next, the spot center position of the laser displacement meter 5 is determined on the two-dimensional CCD 2 by the spot center position detection unit 1f in the same manner as the spot center position of the laser displacement meter 4 is determined in advance. The table 1c is further moved in the y-axis direction by the operation control unit 1g until the position in the y-axis direction becomes the same as the position on the two-dimensional CCD 2 previously obtained for the laser displacement meter 4.

As a result, the distance between the spots at the center positions of the spots of the displacement meters 4 and 5 can be obtained from the amount by which the table 1c is moved by the operation control unit 1g.
Calculates the feed amount of the table 1c which should correspond to the distance between the displacement gauges when performing the measurement by the two-point method sequentially from the movement amount of the table 1c, and moves the table 1c by the feed amount in the y-axis direction. From the output signals of the two laser displacement meters 4 and 5 at the time of the movement, the straight error curve of the object to be measured is sequentially calculated by the two-point method.

The output signals of the two laser displacement meters 4 and 5 are intermittently moved in the y-axis direction by the above-mentioned feed amount by the table 1c so as to be taken into the control device 1b when the table 1c stops. The table 1c may be moved continuously in the y-axis direction without stopping the table 1c.
May be taken into the control device 1b by synchronizing the take-in timing with the point at which the object moves by the feed amount.

By the way, since the two laser displacement meters 4 and 5 were not accurately aligned with the above-mentioned measurement line, the spot of the laser displacement meter 5 after the table 1c was moved in the y-axis direction. If the center position on the CCD 2 is shifted in the x-axis direction from the position previously obtained for the spot center position of the laser displacement meter 4, the shift amount and the movement amount of the table 1 c in the y-axis direction, or Move the table 1c in the x-axis direction to set the spot center position of the laser displacement meter 5 to CC.
On D2, the x of the table 1c at the time when the position exactly matches the position previously obtained for the spot center position of the laser
From the amount of movement in the axial direction and the amount of movement in the previous y-axis direction, the deviation angle of the two laser displacement gauges 4 and 5 in the alignment direction with respect to the measurement line is obtained, and the two laser displacements are calculated by the deviation angle. By rotating the alignment directions of the total of the laser displacement meters 4 and 5 or by rotating the measurement lines,
Must be aligned on the measurement line.

In this case, the feed amount of the table 1c when the measurement is sequentially performed by the two-point method is represented by the square of the shift amount when the table 1c is first moved in the y-axis direction and the spot by the trigonometric method. The center position may be determined by the square root of the sum of the square of the shift amount in the x-axis direction and the square of the displacement amount in the x-axis direction.
An operation may be performed to match the spot positions on the table 2, and the spot position may be obtained from the movement amount of the table 1c in the y-axis direction at that time. When the measurement line is rotated, the table 1c
Is also moved in the x-axis direction while moving in the y-axis direction, so that the two laser displacement gauges 4 and 5 move relative to the measurement object along the measurement line. The measurement is performed according to.

Therefore, in this embodiment, the machine tool main body 1a corresponds to the holding member relative moving means and the control device 1b corresponds to the arithmetic processing means. According to the method, when the displacement meter holding member 3 is relatively moved with respect to the measurement object, the spot center positions of the laser beams B having the small spot diameters of the two laser displacement meters 4 and 5 are accurately matched, and the two laser displacements are changed. Since relative displacement data for accuracy measurement by the two-point method can be obtained sequentially from the total 4 and 5, data deterioration due to repeated measurement can be prevented, and the relative position between the spot diameter center position and the apparatus main body can be prevented. In order to satisfy the principle of the sequential two-point method without requiring a high-precision device configuration and a lot of work to guarantee the relationship,
Data can be obtained by moving the laser displacement meter along a measurement line in a predetermined positional relationship.

Moreover, according to the apparatus of this embodiment, the relatively inexpensive two-dimensional CCD 2 is used as the optical sensor fixed to the object to be measured toward the laser displacement meters 4 and 5, so that it is used.
The laser beam spots of the laser displacement meters 4 and 5 can be accurately
It can be detected at low cost.

In the above embodiment, the case where the two-dimensional CCD 2 is used for detecting the laser beam spot has been exemplified. However, instead of the two-dimensional CCD 2, a light receiving surface two-part photoelectric conversion element is used, and the extending direction of the dividing line is x. After adjusting the position of the laser displacement meter 4 so that the output signal level on both sides of the dividing line when the laser beam spot is applied to the photoelectric conversion element in the axial direction is the same, the table 1c is moved.
The position of the laser displacement meter 5 may be determined so that the laser beam spot of the laser displacement meter 5 exhibits the same output signal level, and the interval between the two displacement meters may be obtained by the control device of the machine tool.

In the above embodiment, a machine tool driven by both the table and the spindle head is used. However, a machine tool with a fixed table and a gate-type structure, a machine tool with a fixed table drive and a fixed spindle head, or a similar machine tool Even with a three-dimensional measuring device having a drive system, the above-described relative movement can be performed, and the shape accuracy measuring device of the present invention can be configured.

FIG. 4 is a perspective view schematically showing another embodiment of the shape accuracy measuring device according to the sequential two-point method of the present invention. In the drawing, the same parts as those in the previous embodiment are the same. Indicated by reference numerals. In the shape accuracy measuring device of this embodiment, instead of providing the two-dimensional CCD 2 as a measurement object in the previous embodiment,
A television camera 9 as an electronic camera having a two-dimensional CCD and an optical system is fixed to an appropriate stationary portion on the machine tool main body 1a as a holding member relative moving means, for example, a portal column 1d.

In the above embodiment, the two-dimensional CCD 2 is arranged on the table 1c. To arrange the two-dimensional CCD 2, it is necessary to perform an operation corresponding to the two-dimensional CCD 2, and it is necessary to remove it during processing. Challenges remain. As a method for solving such a problem, in this embodiment, a column-shaped column is provided as described above.
Place and fix the TV camera 9 in 1d, and
Then, the spot BS of the laser beam projected on the table 1c from the laser displacement meters 4 and 5 is directly magnified and observed, and the image signal output from the television camera 9 is input to the control device 1b. In order to facilitate observation of the spot BS, a suitable reflecting surface may be provided at a position on the table 1c substantially corresponding to the distance between the laser displacement meters 4 and 5 with the same height in the Z-axis direction. .

The apparatus of this embodiment uses the television camera 9 and the laser beam spot BS of one of the laser displacement meters 4.
From the image signal output by the television camera 9, the position (x, y coordinates) of the center position of the spot BS on the table 1 c on the table 1 c is obtained from the image signal output by the television camera 9 by capturing the irregular reflection light or the specular reflection light from the camera. After that, the table 1c is moved in the y-axis direction, and the laser beam spot BS is captured in the visual field of the television camera 9 with respect to the other laser displacement meter 5,
The position on the table 1c is obtained in a similar process. As a result, the distance between the laser displacement meters 4 and 5 can be determined with high accuracy, and the two-point method can be sequentially performed.

According to the apparatus of this embodiment in which the television camera 9 is installed on a stationary part of the machine tool main body 1a instead of installing the two-dimensional CCD on the table 1c, the television camera 9
Since the position of the measurement is fixed, not only the operability is improved, but also the confirmation before and after the use of the displacement meter (confirmation that the accuracy of the device has not changed before and after the measurement use on the measurement object) ) And periodic accuracy confirmation when the device is used for a long period of time, which facilitates maintenance relating to the displacement accuracy of the displacement gauge, thereby improving the workability of the accuracy measurement work. .

By the way, according to the laser displacement meter, the distance from the displacement meter to the object to be irradiated with the laser can be made large, and it is possible to eliminate a situation where the displacement meter collides with a workpiece by mistake. It becomes possible. However, the laser displacement meter has a disadvantage that the measured value becomes unstable due to the small spot diameter and the influence of the processed surface roughness, the processed surface reflectance, the processed surface material, etc., in combination with the characteristics of the laser beam. Have. Therefore, even if the spot position of the laser beam is accurately adjusted to the feed interval and a device that satisfies the measurement principle of two points sequentially is configured, the measurement accuracy may be deteriorated due to the above-described influence.

FIG. 5 is an explanatory diagram showing a measuring method improved to eliminate such inconvenience. That is, in the ordinary sequential two-point method, data is acquired while sending the laser displacement meter along the measurement line in a combination of 4-5. On the other hand, in the improved measuring method, the feed is finely measured before and after the point defined in 4-5, and the data during this period is averaged to obtain a value of 4-5.
A straightness error curve is obtained as a representative value of the five successively acquired two points data. And during the fine measurement, if the output of the measured value is missing due to the processed surface roughness, the processed surface reflectance, the processed surface material, etc., or if the amplitude becomes extremely large from the average value, Then, an operation of removing and averaging is performed.

According to the improved measuring method, the two-point method can be applied successively while suppressing the effects of the processed surface roughness, the processed surface reflectance, the processed surface material, and the like. It is possible to mount the measuring device on the actual machine tool.

FIGS. 6 (a) and 6 (b) are a plan view and a front view, respectively, showing still another embodiment of the shape accuracy measuring apparatus according to the present invention. Spindle head 1e of gate type structure driven machine tool body 1a
Attach the attachment to the lower end of the spindle protruding from the lower end of the
1h is exchangeably mounted, and its attachment 1h
In addition, a tool 1i is exchangeably mounted, a plurality of exchangeable attachments 1h are stored in an attachment holder 1j, and a plurality of exchangeable tools 1i are stored in a tool magazine 1k.These attachments 1h and tools 1i are An automatic exchange device (not shown) automatically exchanges the components through a path shown by a dotted arrow in the figure. Two of the attachments 1h are provided via the displacement meter holding member 3 in the plurality of attachments 1h. 1h attachment with laser displacement meter fixed
It is included. Note that, instead of the attachment 1h, a tool 1i to which two laser displacement meters are fixed via the displacement meter holding member 3 may be included in the plurality of tools 1i.

According to the apparatus of this embodiment, the evaluation of the straightness error curve and the flat error surface can be easily realized in the machining process.

As described above, the laser displacement meter is mounted on three or all four of the four projecting portions 3a of the displacement meter holding member 3 fixed to the attachment 1h or the tool 1i. The three or four laser displacement meters may be aligned in two directions perpendicular to each other, so that the two directions perpendicular to one another among the three or four laser displacement meters By selectively using the two that are aligned with any of the above, flatness measurement can be performed without replacing the laser displacement meter or displacement meter holding member, and the flatness measurement can be easily and automatically performed with high accuracy It can be carried out.

On the other hand, the displacement meter holding member 3 holds two laser displacement meters, and the attachment 1h or the tool 1i to which the displacement meter holding member 3 is fixed is attached to the spindle head 1e corresponding to the holding member rotating means. The two laser displacement meters may be selectively aligned in two directions perpendicular to each other by rotating the main shaft 90 ° by the rotation of the main shaft by the drive of the laser. The flatness can be measured without replacing the holding member, and the flatness can be easily and automatically measured with high accuracy.

In those cases, the X-axis or Y-axis
In the axial direction, measurement is performed sequentially by the two-point method, and then
If the measurement by the two-point method is sequentially performed in the Y-axis or X-axis direction remaining from each measurement point, the flatness measurement can be performed with higher accuracy.

Thus, according to the present invention, a sequential two-point straightness measuring method which has not been put to practical use with a machine tool, a three-dimensional measuring device or the like due to a problem associated with a displacement meter, although its advantages have been recognized so far. In order to overcome the problems of using a laser displacement meter, it was possible to improve the machining accuracy and machining efficiency of machine tools. Evaluation, measurement accuracy improvement, measurement accuracy maintenance, management, etc. can be performed.

Although the present invention has been described above with reference to the illustrated examples, the present invention is not limited to the above-described examples. Although the arithmetic processing of the point method is performed, the arithmetic processing may be performed by a computer provided separately from the control device. Further, in the above embodiment, the two-dimensional CCD is used as the optical sensor. However, if two laser displacement meters can be mechanically accurately aligned on the measurement line, the primary laser is extended so as to extend in the y-axis direction. An original CCD (so-called line sensor) may be arranged and used.

Further, according to the present invention, a shape accuracy measuring device is constituted by using a two-dimensional optical sensor such as the above-mentioned two-dimensional CCD or the above-mentioned television camera incorporating the same as an optical sensor to determine the distance between laser displacement meters. The displacement gauge holding member aligns the two laser displacement gauges at regular intervals along the direction of extension of the measurement line set for the measurement target of the shape accuracy, and measures the two laser displacement gauges for the measurement. The holding member relative movement means moves the holding member relative to the measurement object along the measurement line, and then moves the holding member relative to the measurement object at approximately the same distance from the object and holds it toward the measurement object. The two laser displacement meters are moved relative to each other in the alignment direction, and the two-dimensional optical sensor sets the position of the laser beam from the two laser displacement meters illuminated on the measurement object to the displacement meter holding unit. The two laser displacement meters in the measurement object are detected in accordance with the relative movement of the displacement meter holding member with respect to the measurement object along the measurement line, while sequentially detecting the two laser displacement meters with the relative movement of the measurement object. The displacement from the position where the laser beam from one of the laser displacement meters is irradiated on the two-dimensional optical sensor to the position where the laser beam from the other laser displacement meter is irradiated on the two-dimensional optical sensor The distance and alignment direction of the two laser displacement meters were determined from the relative movement amount of the gauge holding member and the irradiation position of the laser beam from the two laser displacement meters on the two-dimensional optical sensor, and the obtained values were obtained. Each time the displacement meter holding member relatively moves in the direction in which the two laser displacement meters are aligned by a distance equal to the distance between the two laser displacement meters, the two laser displacements are set. Uptake output signal, obtains a straight error curve of the measurement target by arithmetic processing based on those output signals sequentially two-point method, may output it.

In this way, similar to the previous embodiment,
The data can be prevented from being deteriorated due to repeated measurement, and the two-point method can be performed successively without requiring a high-precision device configuration or a lot of work to guarantee the relative positional relationship between the spot diameter center position and the device body. In order to satisfy the principle, the data can be obtained by moving the laser displacement meter in a predetermined positional relationship along the measurement line, and in particular, the displacement meter holding member can be accurately and automatically moved to the two laser displacement meters. Therefore, the device can be mounted on a machine tool or the like, and the shape accuracy can be easily measured sequentially by the two-point method.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a laser displacement meter for measuring shape accuracy by a sequential two-point method using an NC machine tool according to an embodiment of the present invention. It is a perspective view showing typically an example of an accuracy measuring device.

FIGS. 2A, 2B, and 2C are enlarged front views, bottom views, and AA in a front view showing a displacement meter holding member used in the apparatus of the above embodiment. It is sectional drawing which follows a line.

FIG. 3 is a block diagram functionally showing a configuration for obtaining a distance between two laser displacement meters from an output signal of a two-dimensional CCD in the apparatus of the embodiment.

FIG. 4 is a perspective view schematically showing another embodiment of the shape accuracy measuring apparatus according to the sequential two-point method of the present invention.

FIG. 5 is an explanatory diagram showing an improved measurement method in a sequential two-point method using a laser displacement meter.

FIGS. 6 (a) and (b) are a plan view and a front view showing still another embodiment of the shape accuracy measuring device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Machine tool 1a Machine tool main body 1b Control device 1c Table 1d Gate column 1e Spindle head 1h Attachment 1i Tool 1j Attachment holder 1k Tool magazine 2 CCD 3 Displacement gauge holding member 4, 5 Laser displacement gauge 6 Guide rod 7 Micrometer 8 Bracket 9 TV camera

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Teruyasu Hiragami 2068-3 Ooka, Numazu-shi, Shizuoka Pref. JJ26 MM02 PP05 PP12 3C029 BB01 BB10

Claims (11)

[Claims] 1. Two laser displacement gauges (4, 5) are aligned at regular intervals along the extension direction of a measurement line set for a shape accuracy measurement object (1c), and the two laser displacement meters are aligned. A displacement meter holding member (3) for holding the displacement gauge at an approximately equal distance from the measurement object and holding the displacement meter toward the measurement object; and moving the displacement meter holding member relative to the measurement object along the measurement line. Holding member relative movement means (1a); and an optical sensor (2) for sequentially detecting the position of the laser beam from the two laser displacement meters illuminating the measurement object with the relative movement of the displacement meter holding member And the position of the laser beam from one of the two laser displacement meters of the two laser displacement meters in the measurement object along with the relative movement of the displacement meter holding member, and the position of the laser beam from the other laser displacement meter. Each time the displacement meter holding member relatively moves by a distance equal to the distance between the two laser displacement meters obtained from the relative movement amount of the displacement meter holding member until the output signals of the two laser displacement meters are compared, And a processing means (1b) for calculating the straightness error curve of the object to be measured by sequentially processing the output signals based on the two-point method. Accuracy measuring device. 2. The device according to claim 1, wherein the optical sensor is a one-dimensional or two-dimensional charge-coupled device fixed to the object to be measured directed to the laser displacement meter. Shape accuracy measuring device by sequential two-point method. 3. The photoelectric conversion device according to claim 2, wherein the light sensor is a light-receiving surface two-division photoelectric conversion element or a light-receiving surface four-division photoelectric conversion element fixed to the object to be measured facing the laser displacement meter. A shape accuracy measuring device according to the sequential two-point method according to 1. 4. The electronic camera according to claim 1, wherein the optical sensor is an electronic camera fixed to a stationary portion of the holding member relative moving means, facing the object to be measured.
A shape accuracy measuring device according to the described sequential two-point method. 5. The laser displacement meter fine adjusting means (7) for finely adjusting at least one of a relative position and an orientation of the two laser displacement meters. A shape accuracy measuring apparatus according to any one of claims 1 to 4, wherein the shape accuracy measuring apparatus is a sequential two-point method. 6. The arithmetic processing means averages a plurality of output signals of each of the two laser displacement meters when the displacement meter holding member moves a plurality of times at minute intervals, and calculates
6. An apparatus according to claim 1, wherein said output signals are output signals of said two laser displacement meters for arithmetic processing based on a point method. 7. The two laser displacement gauges (4, 5) are arranged at regular intervals along the extension direction of the measurement line set for the shape accuracy measurement object (1c), and the two laser displacement gauges are aligned. A displacement meter holding member (3) for holding the laser displacement meter at a distance of approximately the same distance from the object to be measured and holding it toward the object to be measured; Holding member relative movement means (1a) for relatively moving and relatively moving in the direction in which the two laser displacement meters are aligned, and for measuring the position of the laser beam from the two laser displacement meters irradiated to the object to be measured by the displacement meter A two-dimensional optical sensor (2) that sequentially detects the relative position of the holding member, and the two-dimensional optical sensor (2) of the measuring object along with the relative movement of the displacement meter holding member along the measurement line with respect to the measuring object. From the position where the laser beam from one of the laser displacement meters is irradiated onto the two-dimensional optical sensor to the position where the laser beam from the other laser displacement meter is irradiated onto the two-dimensional optical sensor From the relative movement amount of the displacement meter holding member up to and the irradiation position of the laser beam from the two laser displacement meters on the two-dimensional optical sensor, the interval and alignment direction of the two laser displacement meters are obtained. Each time the displacement meter holding member relatively moves by a distance equal to the distance between the two laser displacement meters with the relative movement of the displacement meter holding member relative to the measurement target in the alignment direction of the two laser displacement meters. An arithmetic processing means (1b) for taking in output signals of the two laser displacement meters and sequentially processing the output signals based on a two-point method to obtain a straightness error curve of the object to be measured; And wherein the obtaining, shape accuracy measuring device according to the sequential two-point method. 8. The sequential sensor according to claim 1, wherein the displacement meter holding member holds at least three laser displacement meters aligned in two directions perpendicular to each other. Shape accuracy measuring device by point method. 9. The apparatus according to claim 1, further comprising a holding member rotating means for rotating said holding member by 90 ° to selectively align said two laser displacement meters in two directions perpendicular to each other. 8. A shape accuracy measuring device according to any one of items 1 to 7 according to the sequential two-point method. 10. In order to measure the shape accuracy by the sequential two-point method using two laser displacement meters, when determining the interval between the two laser displacement meters as the displacement meter interval used in the sequential two-point method, The two laser displacement meters are aligned at regular intervals along the extending direction of the measurement line set for the measurement object of accuracy, and the two laser displacement meters are separated from the measurement object by substantially equal distances. Holding the two laser displacement meters toward the measurement object, moving the two laser displacement meters relative to the measurement object along the measurement line in the holding state, and irradiating the measurement object with the two laser displacement meters. The position of the laser beam is sequentially detected by the optical sensor in accordance with the relative movement, and one of the two laser displacement meters in the measurement object is measured in accordance with the relative movement. And obtaining the distance of the two laser displacement meter from the amount of movement of the relative movement to the position of the laser beam coincides from the laser beam while the laser displacement meter at a position of a total of,
A laser displacement meter interval measuring method for shape accuracy measurement by a sequential two-point method. 11. In order to measure the shape accuracy by the sequential two-point method by using two laser displacement meters, when determining the interval between the two laser displacement meters as the displacement meter interval used in the sequential two-point method, The two laser displacement gauges are aligned at regular intervals along the direction of extension of the measurement line set for the accuracy measurement object, and the two laser displacement meters are separated from the measurement object by substantially equal distances. And holding the two laser displacement meters relative to the measurement object along the measurement line while maintaining the holding state, and the two laser displacement meters irradiated to the measurement object With the relative movement, the position of the laser beam is sequentially detected by a two-dimensional optical sensor, and with the relative movement of the displacement meter holding member along the measurement line with respect to the measurement object, From the position where the laser beam from one of the two laser displacement meters of the two laser displacement meters in the measurement object is irradiated on the two-dimensional optical sensor, the laser beam from the other laser displacement meter is used as the two-dimensional optical sensor. The distance between the two laser displacement meters from the relative movement amount of the displacement meter holding member up to the position where the two laser displacement meters are irradiated, and the irradiation position of the laser beam from the two laser displacement meters on the two-dimensional optical sensor. Characterized by seeking
A laser displacement meter interval measuring method for shape accuracy measurement by a sequential two-point method.