JP5193101B2 - Reference member for inspection master of optical 3D measuring machine - Google Patents

Description

  The present invention relates to a reference member of an inspection master used for accuracy inspection of an optical three-dimensional measuring machine and calibration of measurement errors.

  Conventionally, for measuring the dimensions of mechanical parts such as automobile engines and transmission cases, the tip of a probe (measuring element) is brought into contact with the object set on the measurement table (bed). A three-dimensional measuring machine adapted to perform is used.

  In order to maintain the measurement accuracy, such a three-dimensional measuring machine is periodically inspected for accuracy and calibrated for measurement errors by using an inspection master that is a highly accurate reference. (See Patent Documents 1 and 2)

  These inspection masters are provided with a plurality of reference members having a reference measurement surface finished with high accuracy so that the probe of the three-dimensional measuring machine contacts, and between the reference measurement surfaces of different reference members by the three-dimensional measuring machine. The accuracy of the three-dimensional measuring machine is evaluated by comparing the actual measurement data such as the distances with the reference value of the inspection master.

  As described above, the contact type three-dimensional measuring machine that measures by bringing the tip of the probe into contact with the object to be measured may be damaged due to contact with the probe or may be easily deformed. It is unsuitable for measuring the dimensions of a measurement object made of a material, and in the case of such a measurement object, an optical three-dimensional measuring machine capable of performing dimension measurement in a non-contact manner is used. .

  An optical three-dimensional measuring machine does not include a probe that contacts the object to be measured, but instead irradiates the surface to be measured with the measurement light and receives the reflected light with a detector such as a CCD camera. It is structured to measure the position of the measurement surface.

  When performing accuracy inspection and measurement error calibration of such an optical CMM, the inspection master manufactured for the contact CMM optically measures the distance to the reference measurement surface. It was not possible to use it because no indicator was provided.

  Therefore, a spherical measurement target surface is provided on the reference member to be mounted on the inspection master, and a plurality of linear grooves intersecting each other at a single point are formed on the measurement target surface. Technology that enables the inspection and calibration of optical 3D measuring machines to be performed in the same way as contact 3D measuring machines by irregularly reflecting the measuring light emitted from the measuring machine and capturing the reflected light. Has been proposed. (See Patent Document 3)

JP 2001-330428 A JP 2002-195820 A Japanese Patent No. 4049272

  The reference member mounted on the inspection master for the optical three-dimensional measuring machine described above is processed extremely finely with the line width of the linear groove serving as an index on the surface to be measured being about 5 μm in order to improve the accuracy of position measurement. Has been.

  For this reason, the reflected light from the linear grooves received by the CCD camera is weak, and particularly when external light such as ambient illumination enters the CCD camera as a surface to be measured, etc. There was a problem that it was difficult to find the intersection position.

  Therefore, the present invention solves the problem of the reference member for the inspection master of the optical three-dimensional measuring machine as described above, and is a linear line that serves as an index for optically measuring the distance provided on the surface to be measured. It is an object of the present invention to provide a reference member for an inspection master of an optical three-dimensional measuring machine that can easily find the intersection position of grooves.

  The reference member for inspection master according to the present invention provided for the above purpose is a reference member for inspection master used for accuracy inspection of an optical three-dimensional measuring machine, and the measurement light emitted from the three-dimensional measuring machine is used. The measurement target surface has a reflective surface, and the measurement target surface is formed of a circular flat surface formed on a spherical surface, and the measurement target surface has a fine linear groove for irregularly reflecting measurement light near the center thereof. Are provided so as to intersect each other at the center position of the surface to be measured, and marker grooves that are wider than the linear grooves and diffusely reflect the measurement light more strongly are adjacent to the outer sides of the respective linear grooves. A plurality of radials are provided in the radial direction of the surface to be measured.

  In the inspection master reference member of the present invention, the linear groove and the marker groove are respectively arranged on two orthogonal diameters on the surface to be measured, and the end portion near the center of the marker groove is pointed like a wedge. It is desirable that a linear groove is continuous at the tip. It is also desirable that the portion excluding the surface to be measured is composed of a spherical surface.

  According to the first aspect of the present invention, when the measurement light is irradiated from the three-dimensional measuring machine onto the surface to be measured of the reference member, the plurality of marker grooves provided outside the linear groove strengthen the measurement light. Because of irregular reflection, it is possible to easily find the position of the intersection of the fine linear grooves inside these marker grooves using the reflected light from the marker grooves as a mark.

  In addition, since the reference member can be easily manufactured by processing a flat surface as a surface to be measured on a sphere such as a ready-made steel ball finished with high dimensional accuracy, high accuracy is obtained and low Can be manufactured at a low cost.

  According to the second aspect of the present invention, the linear groove and the marker groove are respectively arranged on two diameters orthogonal to each other on the surface to be measured, and the end portion near the center of the marker groove has a wedge shape. Since the pointed tip is continuous with the linear groove, it is easier to find the position of the intersection of the linear groove on the extended line of each pointed tip toward the center of the marker groove arranged in a cross shape Can do.

It is a perspective view which shows the state which set the inspection master equipped with the reference | standard member for inspection master of this invention to the optical three-dimensional measuring machine. It is a perspective view of the inspection master with which the reference member for inspection master of the present invention is equipped. It is a top view of the inspection master with which the reference member for inspection master of the present invention is equipped. It is AA sectional drawing of FIG. It is a perspective view of the reference member for inspection master of the present invention. It is a top view of the reference member for inspection masters of the present invention. It is BB sectional drawing of FIG.

  FIG. 1 shows a state in which an inspection master equipped with an inspection master reference member (hereinafter simply referred to as a reference member) according to the present invention is set in an optical three-dimensional measuring machine (hereinafter simply referred to as a three-dimensional measuring machine). As shown in the figure, the three-dimensional measuring machine 1 has a measurement table 2 on which an object to be measured is placed, and is provided on both sides of the measurement table 2 so as to be slidable in the horizontal X direction. The gate-shaped movable frame 3, the head unit 4 slidable in the horizontal Y direction perpendicular to the X direction with respect to the movable frame 3, and the Z direction with respect to the head unit 4, And an elevating cylinder 5 slidably provided in the vertical direction.

  Although not shown, the elevating cylinder 5 includes a laser light source that emits laser light as measurement light toward the object to be measured, and a CCD camera that receives the laser light reflected from the object to be measured. The position of the CCD camera is moved to the desired position on the measurement table 2 together with the laser light source by moving the movable frame 3, the head unit 4, and the lifting cylinder 5 in the X, Y, and Z directions, respectively. It can be positioned dimensionally.

  When the dimensions of the finished surface of a work such as an engine block are measured by the three-dimensional measuring machine 1, the work is placed on the measurement table 2, and laser light is irradiated downward from the lower end of the lifting cylinder 5. Then, it is applied to the surface to be measured of the workpiece, the reflected light is captured by a CCD camera, and the coordinate position of the surface to be measured is measured.

  On the other hand, when performing accuracy inspection of the three-dimensional measuring machine 1 or calibration of measurement errors, a jig pallet 6 is fixed on the measurement table 2 instead of the workpiece as shown in FIG. The inspection master 7 is placed on the pallet 6.

  Then, laser light as measurement light is applied to the measurement surfaces of a plurality of later-described reference members 9 provided on the inspection master 7, and the reflected light is captured by a CCD camera inside the elevating cylinder 5. The coordinate position of the measurement point on the measurement surface of each reference member is measured in the dimension direction.

  2 is a perspective view of the inspection master 7 used in the present embodiment, FIG. 3 is a plan view thereof, and FIG. 4 is a longitudinal sectional view taken along the line AA in FIG. As shown in the figure, an inspection master 7 includes a master body 8 having a shape in which two flat cylindrical portions 8A and 8B having different outer diameters are combined in two stages, and a plurality of spherical shapes attached to the master body 8. It is comprised from the reference | standard member 9 of this.

  The master body 8 is manufactured by machining an invariant steel having a small coefficient of thermal expansion and excellent dimensional stability. As shown in FIG. 4, the upper surface S1 of the lower cylindrical portion 8A and the upper cylindrical portion 8B. Each upper surface S2 is provided with a spherical recess a for attaching the reference member 9.

  In addition, bolt insertion holes 11 are formed in the central portions of these recesses a for passing bolts 10 for fixing the reference member 9 from below. The lower part of these bolt insertion holes 11 has an inner diameter enlarged to accommodate the head of the bolt 10, and the lower end of the large diameter part is opened on the bottom side of the master body 8.

  As shown in FIG. 3, four reference members 9 are attached to the upper surface S1 of the lower cylindrical portion 8A of the master body 8 at equal intervals in the circumferential direction at 90 ° central angles, and the upper cylindrical portion. Near the periphery of the upper surface S2 of the portion 8B, the reference member 9 on the cylindrical portion 8A side is oriented with a 45 ° shift in the central angle, and at four locations at equal intervals of 90 ° in the circumferential direction. It is attached. In addition, as a raw material of the master main body 8, as long as it has a small thermal expansion coefficient and excellent dimensional stability, quartz, ceramics, or the like may be used instead of the invariant steel.

  Next, FIG. 5 is a perspective view of the reference member 9, FIG. 6 is a plan view thereof, and FIG. 7 is a cross-sectional view taken along the line BB of FIG. A circular flat surface 9A as a surface to be measured is formed on a part of the flat surface 9A. Two linear grooves G intersecting with the center position of the flat surface 9A as an intersection point O, and these linear shapes Four wide marker grooves M extending radially in the diameter direction from both ends of the groove G to the outer periphery of the flat surface 9A are provided.

  In the present embodiment, the reference member 9 is made of an off-the-shelf steel ball having a diameter of 20 mm and finished with high dimensional accuracy, and the linear groove G is formed by electric discharge machining of the flat surface 9A, and is about 5 μm. It is formed in width and depth.

  On the other hand, the marker groove M is formed to have a width of 2 mm and a depth of 0.5 mm by performing electric discharge machining on the flat surface 9A. The end T of each marker groove M near the center of the flat surface 9A is pointed like a wedge, and the linear groove G is continuous at the tip.

  The flat surface 9A of the reference member 9 and the spherical surface outside thereof are finished to be mirror surfaces, and the linear groove G and the marker groove M are finished to the ancestor surface so that incident light is diffusely reflected and lighted. ing.

  As shown in FIG. 7, on the side opposite to the flat surface 9A of the reference member 9, a screw hole 9B having a depth perpendicular to the flat surface 9A and reaching the vicinity of the center of the reference member 9 is formed. 4, the bolt 10 is inserted into the bolt insertion hole 11 from the bottom surface side of the inspection master 7 </ b> A, screwed into the screw hole 9 </ b> B, and tightened to tighten the reference member 9 into the spherical shape of the inspection master body 8. It is seated in the recess a and can be stably fixed in a state of being positioned with high accuracy.

  In this embodiment, the reference member 9 is manufactured by processing a steel ball in order to reduce the manufacturing cost. However, when high shape accuracy is required, a carbide or ruby is used instead of the steel ball. The reference member may be made of a hard material such as ceramics. In that case, if the material is difficult to fix to the master body with bolts, it may be fixed with an adhesive.

  When the inspection master 7 to which the above-described reference member 9 is attached is used to inspect the accuracy of the coordinate measuring machine 1 and to calibrate the measurement error, as shown in FIG. For the member 9, the coordinate value of the intersection point O of each linear groove G is measured by the three-dimensional measuring machine 1.

  Then, the distance between the intersections O of the respective reference members 9 of the inspection master 7 is obtained from these actually measured coordinate values, and these are determined in the inspection master 7 and are the distances between the intersections O of the respective reference members 9. By comparing with the reference value, the accuracy of the three-dimensional measuring machine 1 can be evaluated or calibrated based on the difference between the actually measured value and the reference value.

  At this time, when the measurement light is irradiated onto the flat surface 9 </ b> A formed as the measurement surface of the reference member 9, the wide marker groove M provided around the linear groove G is larger than the linear groove G. Since the measurement light is strongly diffusely reflected and emitted, the reflected light from the marker grooves M can be clearly captured by the CCD camera of the three-dimensional measuring machine 1, and the reflected light is used as a mark to be inside the marker grooves. The intersection position of the linear groove can be easily found.

  In the reference member 9 of the above-described embodiment, two linear grooves G are orthogonally crossed at the center position of the flat surface 9A, and the marker grooves M are formed from both ends of these linear grooves G. Although a total of four radial surfaces are provided in the diameter direction up to the outer periphery of the flat surface 9A, the present invention is not limited to this embodiment, and three or more linear grooves intersect at the center position of the flat surface. In this case, the marker grooves may be provided in pairs corresponding to the number of the linear grooves, one pair on each outer side of each linear groove.

  In addition, in the present embodiment, the end T near the center of the marker groove M is pointed like a wedge and the linear groove G is continuous at the tip, but the end of the marker groove is For example, it may be formed in a semicircular arc shape. Further, the linear groove and the marker groove need not be continuous.

  Further, the reference member 9 described above is used for accuracy inspection and error measurement calibration of the three-dimensional measuring machine 1 using the light source of the measurement light as a laser light source, but is not limited to this, and other light sources such as, for example, The optical three-dimensional measuring machine using a lamp, a light emitting diode, or the like as a light source for measuring light may be used.

  The inspection master reference member of the optical three-dimensional measuring machine according to the present invention irradiates the measurement light with the measurement light, and measures the dimensions of each part of the measurement with the reflected light. Can be used when performing accuracy inspection of an optical three-dimensional measuring machine and calibration of measurement errors.

DESCRIPTION OF SYMBOLS 1 3D measuring machine 2 Measurement table 3 Movable frame 4 Head part 5 Lifting cylinder 6 Jig pallet 7 Inspection master 8 Master main body 8A, 8B Cylindrical part 9 Reference member 9A Flat surface (surface to be measured)
9B Screw hole 10 Bolt 11 Bolt insertion hole S1, S2 Upper surface a Spherical concave portion G Linear groove O Intersection M Marker groove T End

Claims (2)

  A reference member attached to a master body of an inspection master for an optical three-dimensional measuring machine, having a measured surface that reflects measurement light emitted from the three-dimensional measuring machine, and the measured surface is formed on a spherical surface The measurement surface is provided with a plurality of fine linear grooves that diffusely reflect measurement light near the center of the measurement surface so as to intersect each other at the center position of the measurement surface. In addition, a plurality of marker grooves that are wider than the linear grooves and diffusely reflect the measurement light more strongly are provided in the radial direction of the surface to be measured adjacent to the outer sides of the respective linear grooves. Reference member for inspection master of optical 3D measuring machine.   The linear groove and the marker groove are respectively arranged on two diameters that are orthogonal to each other on the surface to be measured, the end near the center of the marker groove is pointed like a wedge, and the tip is continuous with the linear groove. The inspection master reference member for an optical three-dimensional measuring machine according to claim 1.

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