JP2009216504A - Dimension measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dimension measuring system capable of automatically measuring a diameter along the rotational axis center continuously and precisely for an object in a shape of rotating body and quickly completing the measurement without contact only by setting the measurement object at the measurement object dispense with inputting and teaching the measurement procedure to a control device for a measurement object in a shape of rotating body having a multistage diameter as an object to extremely reduce the load of an operator. <P>SOLUTION: In this dimension measuring system, a light projecting part 3 which projects LED parallel light R having width in the horizontal direction and a light receiving part 4 which has a line shaped light receiving element 4a are oppositely attached to the horizontal direction to a lift frame 2 which is driven in the vertical direction by a one-axis robot 1, and a measurement object W in a shape of rotating body having a multistage diameter in the passage region of the parallel light R is vertically set. By irradiating the parallel light R to the measurement object W while continuously moving the lift frame 2, the border position of the shadow S caused by the measurement object W is detected at the light receiving part 4 and the diameter of the measurement object W is continuously measured based on the detection data. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dimension measuring system for continuously and automatically measuring a diameter along a rotation axis of a measurement object having a rotating shaft shape such as a round shaft or a cylinder having a multistage diameter.

  Conventionally, in order to determine whether a dimensional error is within the allowable range of a product, for example, a round shaft shape or a cylindrical shape having a multistage diameter such as a punch for press, the diameter and length are determined. Is measured with high accuracy in the unit of μm, a skilled worker is exclusively manually using a micrometer. However, since a high level of skill is required for such measurement work, there is a problem that it takes a long time to train a suitable worker, and the measurement value varies depending on the worker. In addition, even if a high level of skill is required for the measurement, since the operation itself is a repetition of simple work, there is also a problem that it causes great mental pain to the worker.

  Therefore, in recent years, various types of automation of dimension measurement using robots and the like have been studied, but in particular, when dealing with a large number of products to be measured and a small lot, the sizes and forms that correspond to each product type are supported. Since it takes a lot of time and effort to formulate a measurement procedure and to input and teach the measurement procedure to the control device, it has been difficult to realize in terms of work efficiency and economy.

  In view of the above circumstances, the present invention is capable of continuously and automatically measuring the diameter along the rotation axis of a rotating object having a multistage diameter, in particular, and measuring the type of the measuring object. There is no need to input and teach the measurement procedure to the control device every time, and the measurement can be completed quickly without contact by simply placing the object to be measured at the measurement position, which can significantly reduce the burden on the operator. The purpose is to provide.

  If a means for achieving the above object is shown with reference numerals in the drawings, the dimension measuring system according to claim 1 of the present invention is installed horizontally on a lifting frame 2 that is numerically controlled by a uniaxial robot 1 in the vertical direction. A light projecting unit 3 that projects parallel light R of an LED (Light Emitting Diode) having a width in the direction and a light receiving unit 4 that includes a line-shaped light receiving element 4a that receives the parallel light R face each other in the horizontal direction. The rotating object-shaped measurement object W is installed in the passage area of the parallel light R so that the axis of rotation is perpendicular to the parallel light R, and the parallel light R is continuously moved while the elevating frame 2 is moved continuously. By irradiating the object to be measured W, the light receiving unit 4 detects a boundary position of the shadow S by the object to be measured W, and measures the diameter of the object to be measured W based on this detection data.

  According to a second aspect of the present invention, in the dimension measuring system according to the first aspect, the workpiece W has a multi-stage diameter (D1 to Dn).

  A third aspect of the present invention is the dimension measuring system according to the first or second aspect, wherein the measured object W has a form capable of self-supporting with the direction of the rotation axis being vertical on a horizontal plane, and the measured object W is positioned at the measurement position. It is set as the structure which mounts upright (on the measurement table 8), and performs the said measurement.

  According to a fourth aspect of the present invention, in the dimension measuring system according to any one of the first to third aspects, the laser beam L is emitted downward near the top end of the uniaxial robot 1, and the distance to the reflecting surface is measured by the reflected light. The laser distance sensor 6 is attached, and the laser beam L is reflected at the top of the object to be measured W, so that in addition to the measurement of the diameter, the axial length of the object to be measured W is determined from the distance to the reflecting surface. It is configured to measure.

  According to a fifth aspect of the present invention, in the dimension measuring system according to the fourth aspect, the workpiece W has a non-planar top portion Wa, and the top portion Wa of the workpiece W includes a horizontal top surface 7a. The measurement auxiliary cap 7 whose top thickness is known is covered, and the laser light L is reflected by the top surface 7a of the measurement auxiliary cap 7 to measure the axial length of the object W to be measured.

  According to a sixth aspect of the present invention, in the dimension measuring system according to the fourth aspect, the auxiliary measuring plate 13 having a known thickness that can be moved up and down along the vertical guides (guide pins 11...) While maintaining the horizontal posture at the measurement position. The auxiliary measuring plate 13 is disposed on the upper side by the support 14 provided on the lifting frame 2 and has a non-planar top portion Wa below the auxiliary measuring plate 13. By installing the object to be measured W and lowering the elevating frame 2 at the time of measurement, the auxiliary measuring plate 13 is lowered along the vertical guide by its own weight, and the object to be measured W is held from the receiver 14 while maintaining the horizontal posture. The axial length of the workpiece W is measured by reflecting the laser beam L on the upper surface of the auxiliary measuring plate 13.

  If the effects of the present invention are indicated with reference numerals in the drawings, the dimension measurement system according to claim 1 starts the measurement by installing the workpiece W at the measurement position so that the direction of the rotation axis is vertical. Then, the parallel frame R of the LED is automatically irradiated onto the object W while the elevating frame 2 is continuously moved up and down, and the boundary position of the shadow S by the object W is detected from the light / dark difference in the light receiving unit 4. Then, the diameter of the workpiece W is measured by a calculation process based on the detection data. Therefore, high-efficiency and high-accuracy measurement can be performed without requiring skill, and it is not necessary to pre-determine a measurement procedure and input and teach it to a computer. In the case of an object, it is not necessary to create a measurement procedure and to input and teach a computer, and it is not necessary to install the object to be measured W so that it enters the passage of parallel light R. Since positioning is not necessary, the burden on the operator is significantly reduced.

  According to the second aspect of the present invention, it is possible to easily measure the diameter of each stage continuously and with high accuracy for the workpiece W having a multi-stage diameter (D1 to Dn).

  According to the invention of claim 3, since the object to be measured W has a form that can stand independently with the direction of the rotation axis being vertical on a horizontal plane, the object W is simply placed upright at the measurement position. Easy measurement.

  According to the invention of claim 4, in the above dimension measurement system, in addition to the measurement of the diameter of the workpiece W, the axial direction of the workpiece W is measured by the laser distance sensor 7 provided near the top end of the uniaxial robot 1. The length can be measured simultaneously.

  According to the fifth aspect of the present invention, when the object to be measured W has a non-planar top portion Wa, the top end position of the object to be measured W (axis O ) Is slightly deviated from the optical axis of the laser beam L of the laser distance sensor 6, as long as the laser beam L strikes even the horizontal top surface 9 a of the measurement auxiliary cap 9, the axis of the object W to be measured without any problem. The direction length can be measured.

  According to invention of Claim 6, when the to-be-measured object W has a non-planar top part Wa, the top end of the to-be-measured object W is mounted by placing the measurement auxiliary plate 13 lowered from above on the top part Wa. Even if the position (axial center O) is deviated from the optical axis of the laser beam L of the laser distance sensor 6, the laser beam L is reflected from the upper surface of the measurement auxiliary plate 13, and therefore the axial direction of the object W to be measured without any trouble. The length can be measured.

  Hereinafter, an embodiment of a dimension measuring system according to the present invention will be specifically described with reference to the drawings. FIG. 1 shows an example of the configuration of a measuring apparatus used in this dimension measuring system, FIG. 2 shows the principle of diameter measurement by this dimension measuring system, FIG. 3 shows a measurement state by this dimension measuring system, and FIG. FIG. 5 shows a method for interpolating correction data, and FIG. 6 shows a method for measuring the height of an object having a pointed apex.

  In FIG. 1, 1 is a single-axis robot for moving up and down, 2 is a lifting frame that is numerically controlled by the single-axis robot 1 in the vertical direction, 3 is a light projecting unit that is attached to the left side of the lifting frame 2, and 4 A light receiving unit 5 mounted on the left side and disposed opposite to the light projecting unit 3 in the horizontal direction, 5 is a surface plate that sets the upper surface horizontally, and 6 is erected near the rear of the surface plate 5 to hold the uniaxial robot 1. A support base frame that is held vertically, 7 is a laser distance sensor that is attached to the front end of a bracket 61 that projects forward from the top end of the support base frame 6, and 8 is a vertical cylindrical measurement table placed on the surface plate 5, W is a round shaft-like object to be measured having a multistage diameter upright on the measurement table 8.

  As shown in FIG. 2, the light projecting unit 3 converts the LED light emitted from the LED light emitting element 3a into parallel light R having a width in the horizontal direction by the collimator lens 3b and projects the light. On the other hand, the light receiving section 4 forms an image of incident parallel light R on the surface of a linear light receiving element 4a such as a CCD (charge coupled device) through a light receiving lens system 4b such as a telecentric optical system, and the light information is received by the light receiving section 4b. It is converted into an electric signal by the element 4a and input to the computer C. Thus, as shown in the drawing, the presence of the object W to be measured in the passage region of the parallel light R causes a part of the parallel light R to be blocked to generate a shadow S, and the boundary positions on both sides of the shadow S are Since it is detected as a bright and dark edge, the computer C performs a required calculation process based on the electrical signal including the information, and the diameter of the workpiece W is measured with high accuracy, and the display output at each stage is the maximum value. Necessary values such as the median value (the value at the center of the stage) and the average value are obtained and displayed on the display device G.

  Incidentally, as a suitable commercially available dimension measuring device having such an LED light projecting unit and a CCD light receiving unit, there is a digital dimension measuring device LS-7000 series (green LED used) manufactured by Keyence Corporation. As another dimension measuring instrument, the outer diameter of the laser beam emitted from the semiconductor laser is irradiated on a rotating polygon mirror by a motor, and the measurement range is scanned and input to the light receiving element. Although there is a laser scan type that measures dimensions such as, there is a problem in durability and stability due to motor capability etc. in order to perform high-speed and high-precision measurement.

  In the dimension measuring system according to the present invention, the light projecting unit 3 and the light receiving unit, which have a posture in which the width direction of the emitted parallel light R is horizontal, are arranged in the vertical direction using a single-axis robot in a state of being opposed to each other in the horizontal direction. While setting to be numerically controlled, a light projecting that moves up and down by placing a rotating object-shaped object W on the measuring table 8 on the surface plate 5 so that the direction of the rotation axis is vertical. The parallel light R of the LED emitted from the unit 3 can be irradiated over the entire length from the lower end to the upper end of the object to be measured W.

  In order to measure the diameter of each stage of the workpiece W having multi-stage diameters (nominal diameters D1 to Dn) with high accuracy, the projector frame 3 is moved from the light projecting unit 3 while continuously moving the elevating frame 2 upward or downward. The parallel light R of the emitted LED is continuously irradiated onto the object to be measured W, and the measurement value is taken into the computer C at a predetermined short time interval (usually several tens of milliseconds). As described above, the display device G displays the maximum value, median value, average value, etc., according to the purpose of the measurement, so that the computer C calculates the measured value and displays it from a large number of measured values. Find the value.

  In order to identify that the irradiation position of the parallel light R has moved to a different step portion of the workpiece W during the measurement, for example, the first fetch value d1 belonging to the first stage nominal diameter D1 and the next and subsequent times. When the absolute value of the difference between the captured values dn exceeds a preset value Δx1, it is assumed that the irradiation position has shifted to a region belonging to the second nominal diameter D2. When the fetch value dn at that time is d2, and similarly, when the difference between d2 and the fetch value dn from the next time exceeds the set value Δx2, a transition is made from the second stage area to the area belonging to the third stage nominal diameter D3. In the same manner, the transition to the next nominal diameter area may be identified. If there is no extreme difference in diameter between the nominal diameters of the respective stages, the same identification as described above can be performed without any trouble even if the set value is a single value Δx. Further, the moving speed of the lifting frame 2 in the measurement is usually about 1 to 20 mm / sec. However, the moving speed is not limited to a constant value, and, for example, the transition portion of the multistage diameter is tapered according to the shape of the multistage diameter of the workpiece W. You may change suitably, such as making it low-speed in the area | region which makes a shape.

  In this measurement, it is only necessary to place the workpiece W so as to enter the passage region of the parallel light R, and since strict positioning is unnecessary, the burden on the operator is remarkably reduced. Thus, the workpiece W to be measured is not limited to the one having the multi-stage diameter illustrated in FIGS. 1 and 3, and may be a rotating body shape. In such a form, it is only necessary to place the apparatus upright on the horizontal plane at the measurement position, so that the operation becomes easier. However, even if the object to be measured W has a thin bottom end and is easy to fall down, or the bottom surface is convex and cannot stand on its own, if the rotation axis can be held vertically using an appropriate auxiliary jig, the measurement will be hindered. Absent. For example, even if the object to be measured W is a sphere, as shown in FIG. 9, it is possible to measure by simply using the mounting table 15 having an inverted conical recess 15a on the upper surface and placing it on the recess 15a.

  By the way, in such a dimension measurement by the light projecting unit 3 and the light receiving unit 4 of the LED, there is almost no variation in the measured value by the same measuring device, but there is a deviation of the measured value unique to each measuring device. This is due to slight differences in lens aberrations of the optical system and distortion during assembly and installation of the optical system and the entire device. It is desirable to detect the degree of deviation in advance and calibrate the measured value according to the degree of deviation. There are the following methods as specific means of this calibration.

  First, in order to obtain fluctuations in measurement values unique to individual measurement apparatuses, for example, a master work M having a multistage diameter (nominal diameters D1 to D5) as shown in FIG. 4 is produced. This master work M assumes a normal diameter measurement range in the measurement device, D1 is a diameter near the minimum measurement range, D5 is a diameter near the maximum measurement range, and D2 to D4 are between D1 and D5. Let the diameter difference be an evenly divided diameter. And the precise value of these nominal diameters D1-D5 is measured by a highly reliable separate high-precision measuring means, and these are set as absolute diameters D1s-D5s. Next, the nominal diameters D1 to D5 of the master work M are measured by the measuring device having the light projecting part 3 and the light receiving part 4 of the LED used in the present invention, and these are measured diameters D1m to D5m and absolute diameters D1s to D5s. (D1s-D1m for the nominal diameter D1 and the same for the nominal diameters D2 to D5), and this difference is used as the correction values Δa to Δe. That is, it is as follows.

Nominal diameter D1 D2 D3 D4 D5
Absolute diameter D1s D2s D3s D4s D5s
Measurement diameter D1m D2m D3m D4m D5m
Correction value: Δa Δb Δc Δd Δe

Therefore, the measurement diameter is calibrated using this correction value, and for example, the measurement diameter D1m is output as D1s with the correction value Δa added. As shown in FIG. 5, for example, if the measured diameter Dm is a value that falls between D2m and D3m, the correction value Δp is obtained by interpolating between the correction values Δb and Δc, and the output is Dm + Δp. Good. That is, X = D3m−D2m, Y = Δc−Δb,
Δp≈Y (Dm−D2m) / X
It becomes.

  In the above calibration method, the correction value Δp is obtained by interpolating between the measured diameters D2m and D3m. However, an appropriate correction value is obtained by least squares quadratic approximation using three or more known correction values before and after. May be. In addition, the number of multi-stage diameters of the master work M can be variously set in addition to the illustrated example 5. The more the master work M is, the more accurate calibration can be performed. Therefore, the calibration method using these correction values can also be applied to interpolation of measurement values of the axial length of each nominal diameter region of the workpiece W.

  On the other hand, in the dimension measurement system of this embodiment, as shown in FIG. 3, the axial length of the workpiece W can be measured simultaneously by the laser distance sensor 7 provided in the vicinity of the top end of the uniaxial robot 1. This is because the laser beam L is emitted from the laser distance sensor 7 in an obliquely forward and backward direction (FIG. 3 is shown vertically for the front view), and the laser beam L is reflected at the top of the object W to be measured. Then, the distance to the reflecting surface is measured by capturing the reflected light, and the axial length is measured from this distance and the known height of the installation surface of the W to be measured.

  If the top of the object to be measured W is a flat surface perpendicular to the axial direction, the axial length can be accurately measured no matter where the laser light L hits the flat surface. As described above, precise positioning is not required when the workpiece W is installed. On the other hand, as shown in FIG. 6A, when the object to be measured W has a non-planar apex Wa such as a pointed shape, the irradiation position of the laser light L from the laser distance sensor 7 is the object to be measured W. If it deviates from the axial center O, the reflection position will be shifted to a position lower than the top portion Wa by the distance e, and the precision cannot be measured. However, it is extremely difficult to make the reflection position exactly coincide with the top portion Wa.

  Therefore, in the case of the workpiece W having the tip-like top portion Wa, as shown in FIG. 6 (B), a measurement auxiliary cap 9 having a top surface 9a having a horizontal top surface 9a and a known top thickness t is provided. The laser beam L is reflected by the top surface 9 a of the measurement auxiliary cap 7. In this case, even if the axis O of the object to be measured W is slightly deviated from the optical axis of the laser beam L, the laser beam L is not affected as long as the laser beam L strikes even the horizontal top surface 9a of the measurement auxiliary cap 9. Since the axial length (height) of the workpiece W can be measured, strict positioning is not required when the workpiece W is installed.

  However, since the measurement auxiliary cap 9 adapts the inner diameter to the top diameter of the object W to be measured, a dedicated one is required for each of the top diameters. Not suitable for. Therefore, as an alternative measurement auxiliary device, if an auxiliary measurement plate having a known thickness is movable up and down in a horizontal posture, the difference in the top diameter of the workpiece W can be dealt with.

  In the measurement auxiliary device 10 illustrated in FIG. 7, guide pins 11, which are perpendicular to the four corners of a square measuring table 10 a, are erected, and the top portions of these four guide pins 11 are connected to a square annular top frame 12. In addition, the guide pins 11 are penetrated through the guide tube portions 13a at the four corners (see FIG. 8), and an auxiliary measurement plate 13 that is movable up and down in a horizontal state is provided. 4 and a workpiece W having a non-planar top portion Wa on a measuring table 10a, which is placed on the surface plate 5 so that the inside of the top frame 12 faces directly below the laser distance sensor 7. It is designed to be installed. On the other hand, a receiving tool 14 that projects forward in a bifurcated manner is fixed to the upper center of the lifting frame 2 on the measuring device side.

  At the time of measurement, as shown by a virtual line in FIG. 8, first, the holder 14 of the lifting frame 2 is inserted forward from between the guide pins 11, 11 on the rear side of the measurement auxiliary device 10, and the auxiliary measurement is performed by the receiver 14. The board 13 is supported at the upper level. When the elevating frame 2 is lowered as it is, the auxiliary measuring plate 13 is also lowered with the receiving member 14 by its own weight, but on the way to the non-planar (conical shape in the figure) top Wa of the object to be measured W. The holding tool 14 moves away from the auxiliary measuring plate 13 and continues to descend integrally with the lifting frame 2. Therefore, the laser beam L from the laser distance sensor 7 is irradiated and reflected on the upper surface of the auxiliary measurement plate 13 stopped in a horizontal state, thereby reducing the known thickness of the auxiliary measurement plate 13. The axial length (height) of the object W can be measured. In this case, there is no restriction on the top diameter of the workpiece W to be measured as long as it is thick enough to be arranged inside the guide pins 11. Further, the lowering of the elevating frame 2 may be performed as an operation associated with the diameter measurement described above.

  Note that the measuring device used in the dimension measuring system of the present invention is not limited to the embodiment illustrated in FIGS. 1 and 7, and various configurations can be changed in addition to the detailed configuration such as the shape, size, dimensional ratio, etc. of each part. It is.

It is a perspective view of the whole measuring device used for the dimension measuring system concerning one embodiment of the present invention. It is a schematic diagram which shows the principle of the diameter measurement by the same dimension measurement system. It is a front view which shows the measurement state by the same dimension measurement system. It is a front view of the multistage diameter master workpiece | work for obtaining measured value correction data. It is a correlation diagram of a measured value-correction value for explaining an interpolation method of correction data. The height measurement of the to-be-measured object which has a non-planar top part is shown, (A) is a vertical side view when a measurement auxiliary cap is not used, and (B) is a vertical side view when a measurement auxiliary cap is used. It is a perspective view of the whole measuring device which shows the measurement state of the to-be-measured object which has a non-planar top using a measurement auxiliary device. It is a vertical side view of the principal part which shows the use condition of the measurement auxiliary device. It is a longitudinal cross-sectional view which shows the installation state of a spherical to-be-measured object.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Uniaxial robot 2 Elevating frame 3 Light emission part 3a LED light emitting element 4 Light receiving part 4a Line-shaped light receiving element 5 Surface plate 7 Laser distance sensor 9 Measurement auxiliary cap 9a Top surface 10 Measurement auxiliary device 11 Guide pin (vertical guide)
13 Auxiliary measuring plate 14 Receptor t Top thickness C Computer L Laser light R Parallel light of LED W Object to be measured Wa Non-planar top

Claims (6)

  A light projecting unit that projects parallel light of an LED having a width in the horizontal direction on a lifting frame that is numerically controlled and driven vertically by a single-axis robot, and a light receiving unit that includes a linear light receiving element that receives the parallel light. A rotating object-shaped object to be measured is installed so that the direction of the axis of rotation is perpendicular to the parallel light passing area, and the parallel light is continuously moved while moving the lifting frame continuously. The dimension measuring system is characterized in that the position of the shadow of the object to be measured is detected in the light receiving unit by irradiating the object to be measured, and the diameter of the object to be measured is measured based on the detected data.   The dimension measuring system according to claim 1, wherein the object to be measured has a rotating body shape having a multistage diameter.   3. The dimension measurement according to claim 1, wherein the measurement object has a configuration in which the object to be measured can stand on a horizontal plane with the rotation axis direction vertical, and the measurement is performed by placing the object to be measured upright at a measurement position. system.   Near the top end of the uniaxial robot, a laser distance sensor that emits laser light downward and measures the distance to the reflecting surface by the reflected light is attached, and the laser light is reflected at the top of the object to be measured. The dimension measurement system according to any one of claims 1 to 3, wherein, in addition to measuring the diameter, the axial length of the object to be measured is measured from the distance to the reflecting surface.   An object to be measured W has a non-planar top, and a top of the object to be measured is covered with a measurement auxiliary cap having a horizontal top surface and a known thickness of the top, and the top of the measurement auxiliary cap The dimension measurement system according to claim 4, wherein the axial length of the object to be measured is measured by reflecting the laser beam.   A measurement auxiliary device having an auxiliary measurement plate with a known thickness that can be moved up and down along the vertical guide while maintaining a horizontal posture is arranged at the measurement position, and the auxiliary measurement plate is provided by a support provided on the elevating frame. The object to be measured is supported at the upper level, and a measurement object having a non-planar top portion is installed below the auxiliary measurement plate, and the lifting frame is lowered during measurement, so that the auxiliary measurement plate is removed from the receiver. The dimension measuring system according to claim 4, wherein the length of the object to be measured is measured by transferring to the top and reflecting the laser beam on the upper surface of the auxiliary measuring plate.

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