JP2013013947A - Measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement device with extremely excellent practicality capable of measuring dynamic deflection of an extremely small diameter round rod or an extremely small diameter tool mounted to a spindle to rotate at a high rotational frequency.SOLUTION: This measurement device includes an optical system including a light source, a lens system for leading a light beam from the light source to a member to be measured, and a plurality of photodiodes receiving the light beam via the member to be measured, and measures the position of the member to be measured or deflection amount on the basis of the light receiving amount in the photodiodes. All side portions which cross an axial center of the member to be measured are straight lines in the plurality of photodiodes in an optical-axis direction view of the optical system. At least one gap inclined relative to the axial direction of the member to be measured is provided between the plurality of photodiodes. Both end parts of the gap are located outside an outline of the member to be measured, and the side portions crossing the axial center of the member to be measured other than the side portions of the photodiodes forming the gap are configured so as not to be parallel to the gap.

Description

  The present invention relates to a measuring apparatus.

  With recent high performance and miniaturization of electrical and electronic equipment such as electrical appliances and information communication equipment, high-density mounting of printed wiring boards (PCB) used in these products, miniaturization of molds, and high Accuracy is required. In order to cope with such a situation, the diameter of rotary cutting tools such as drills and end mills has been reduced year by year, and cutting with extremely high accuracy is required.

  The run-out (dynamic run-out) associated with the rotation of the rotary cutting tool has a large effect on the cutting accuracy. Therefore, not only the performance of the rotary cutting tool but also the state of the spindle of the processing equipment used for the cutting process, specifically the spindle movement. It is important to understand the accuracy of the run-out.

  Therefore, a gauge pin (round bar) is attached to the spindle of a processing apparatus used for cutting processing via a chuck, the spindle is rotated, and the state of the spindle is measured by measuring the dynamic deflection of the portion protruding from the chuck of this gauge pin. I know.

  For example, it is a well-known fact in the industry that a rotary cutting tool for printed wiring board (PCB) processing has an outer diameter of a shank portion of 3.175 mm or 2 mm, and a drilling machine for attaching these rotary cutting tools. The chuck inner diameter of a processing apparatus such as 3.175 mm or 2 mm is set.

  Therefore, the outer diameter of the gauge pin is a round bar having an outer diameter of 3.175 mm or 2 mm according to the chuck inner diameter of the processing apparatus. In addition, for example, as disclosed in Patent Documents 1 and 2, a non-contact type that measures the total dynamic runout of a spindle and a rotary cutting tool by attaching a shank portion of a rotary cutting tool such as a drill or an end mill via a chuck A measuring device has been proposed.

  By the way, in order to obtain high cutting accuracy, it is necessary to rotate the rotary cutting tool at an appropriate cutting speed (peripheral speed) according to the specifications of the work material and the rotary cutting tool. In recent years, it is necessary to rotate a very small diameter rotary cutting tool (minimum diameter tool) at a higher rotational speed. In general, it is known that the dynamic runout tends to increase as the rotational speed of the spindle increases and the rotary cutting tool bends and swings due to the centrifugal force.

  Therefore, especially when the spindle is rotated at a high rotation, if the mass of the portion protruding from the chuck (protruding portion) is large, the centrifugal force due to the rotation of the spindle is correspondingly increased and the dynamic vibration tends to increase.

  For this reason, a gauge pin having an outer diameter larger than the outer diameter of the tool body of the ultra-small diameter tool (for example, a round bar having an outer diameter of 3.175 mm) in an attempt to grasp the state of the spindle at the rotational speed when the ultra-small diameter tool is actually used. Since the mass of the protruding part of the gauge pin is larger than the mass of the protruding part of the very small diameter tool, the dynamic deflection of the gauge pin is larger than the dynamic deflection of the extremely small diameter tool. Therefore, there is a risk that an accurate dynamic shake cannot be grasped and the spindle is broken if the dynamic shake is extremely large.

  On the other hand, it may be desirable to measure the overall dynamic runout of the spindle and the small diameter tool by attaching the shank of a small diameter tool such as a drill or end mill to the spindle via the chuck. For the purpose of grasping, in order to further suppress the influence of the shape error of the extremely small diameter tool itself, it is desirable to measure with a simpler gauge pin.

  In this case, in order to make the mass of the protruding portion as close as possible to the mass of the extremely small diameter tool that is actually planned to be used, match the outer diameter of the shank portion of the gauge pin with the inner diameter of the chuck, It is desirable to use a blank-shaped gauge pin (minimum diameter round bar) of a stepped round bar-like ultra-small diameter tool matched to the outer diameter. Here, the blank refers to a tool (stepped round bar shape) in a state before forming a helical chip discharge groove or cutting edge on the outer periphery, for example.

  As described above, in order to achieve high cutting accuracy, it is important to measure the dynamic runout of a small-diameter round bar or a small-diameter tool that is attached to a spindle and rotates at a high rotational speed.

JP-A-1-306156 Japanese Utility Model Publication No. 2000-47

  By the way, the conventional non-contact type measuring apparatus has the following problems.

  Patent Document 1 discloses a device that includes a charge coupled device (CCD) as a light receiving element and obtains the outer diameter and eccentricity of the tool (one of the elements constituting dynamic deflection). However, when a charge-coupled device is used, the detection signal is output in time series and the data extraction time becomes long. Therefore, it is not possible to measure the dynamic deflection of a round bar or tool that rotates at a high rotational speed. Is possible. Further, since the resolution depends on the magnification of the optical system used and the pixel pitch of the CCD, there is a problem that sufficient high resolution may not be obtained.

  Further, in Patent Document 2, two photodiodes are used as light receiving elements, and the photodiodes are spaced apart by a predetermined interval (gap width) (so-called a gap is provided), so that the amount of tool deflection and the amount of vibration can be reduced. An inspection device for measuring the diameter is disclosed.

  The gap is provided with the gap axis parallel to the axial direction of the member to be measured (provided so that the width direction of the gap is orthogonal to the axial direction of the member to be measured). Measurement is possible in a state where the gap is covered by the member to be measured in the entire axial direction of the member. Here, the “gap axis” indicates a virtual line that passes through the middle point of the gap width and is orthogonal to the width direction of the gap.

  Therefore, in the case of such a configuration, when the outer diameter of the member to be measured is smaller than the gap width, or when the dynamic vibration of the member to be measured being rotated is large, the gap cannot be covered. There is a problem that accurate measurement is not possible. In other words, the narrower the gap width, the wider the measurable range, but in reality there is a limit to narrowing the gap width. In the case of extremely small diameter round bars or extremely small diameter tools, each outer diameter is the gap width. There is a problem that it may be smaller than that and cannot be measured.

  The present invention solves the above-described problems, and is capable of measuring the dynamic runout of a very small diameter round bar or a very small diameter tool that is attached to a spindle of a processing apparatus used for cutting and rotates at a high rotational speed. The present invention provides a measuring device with excellent practicality.

  The gist of the present invention will be described with reference to the accompanying drawings.

  An optical system including a light source, a lens system that guides light from the light source to a member to be measured, and a plurality of photodiodes that receive the light through the member to be measured; the amount of light received by the photodiode A measuring device for measuring a position or a shake amount of the member to be measured based on the optical axis of the optical system as viewed in the optical axis direction, the plurality of photodiodes being sides intersecting with the axis of the member to be measured All of the portions are straight, and at least one gap that is inclined with respect to the axial direction of the member to be measured is provided between the plurality of photodiodes. Both ends of the gap are outside the outer shape of the member to be measured. The side portion that is positioned in the direction and intersects the axis of the member to be measured other than the side portion of the photodiode that forms the gap is configured not to be parallel to the gap. Those of the measuring apparatus according to claim.

  2. The measuring apparatus according to claim 1, wherein each of the photodiodes is a polygonal photodiode as viewed in the optical axis direction of the optical system.

  The measurement apparatus according to claim 1, wherein a telecentric optical system is provided between the member to be measured and the photodiode. is there.

  The measuring apparatus according to claim 1, further comprising a lens that focuses the light beam only in an axial direction of the member to be measured on a part of the member to be measured. It is related to.

  The measuring apparatus according to claim 1, wherein a lens that focuses the light beam only in an axial direction of the member to be measured on a part of the member to be measured, and the light beam toward the photodiode. And a lens that irradiates the light as parallel light.

  The measuring apparatus according to any one of claims 4 and 5, wherein the member to be measured is a rotary cutting tool.

  The measurement apparatus according to any one of claims 1 to 6, wherein two photodiodes having the same area and the same shape are provided.

  Since the present invention is configured as described above, it is extremely practical to measure the dynamic runout of a small-diameter round bar or a small-diameter tool that is attached to the spindle of a machining apparatus used for cutting and rotates at a high rotational speed. An excellent measuring device.

It is the schematic explanatory drawing which shows the measurement principle of this invention, and the calculation formula which calculates | requires a voltage difference. It is a structure schematic explanatory top view of a prior art example. It is the schematic explanatory drawing which shows the measurement principle of a prior art example, and the calculation formula which calculates | requires a voltage difference. 1 is a schematic explanatory diagram of a configuration of Example 1. FIG. FIG. 3 is a schematic perspective view illustrating a configuration of a measurement unit according to the first embodiment. 6 is a schematic explanatory diagram of a configuration of Example 2. FIG. FIG. 6 is a perspective view schematically illustrating the configuration of a measurement unit according to a second embodiment. 6 is a schematic explanatory diagram of a configuration of Example 3. FIG. FIG. 10 is a perspective view schematically illustrating the configuration of a measurement unit according to a third embodiment. It is a schematic explanatory front view which shows the structural example of a photodiode.

  An embodiment of the present invention which is considered to be suitable will be briefly described with reference to the drawings showing the operation of the present invention.

  While rotating the member to be measured, light is emitted from a light source (LED: light emitting diode), and the amount of shake of the member to be measured is measured based on the amount of light received by the photodiode. FIG. 1 shows a schematic explanatory diagram illustrating the measurement principle of the present invention and an example of a calculation formula for obtaining a voltage difference.

  At this time, the gap between the photodiodes (the gap axis thereof) is inclined with respect to the axial direction of the member to be measured, and both ends of the gap (outside the optical axis direction of the optical system) are outside the outer shape of the member to be measured. For example, when two photodiodes are arranged as shown in FIG. 1, the amount of light received by each photodiode (converted from a current generated according to the amount of received light to a voltage). It is possible to measure the shake amount. Note that, in a state where the member to be measured is not disposed between the light path from the LED serving as the light source to the photodiode, the entire region of the photodiode is set to be irradiated with the light beam from the LED.

  Therefore, even when the outer diameter of the member to be measured is smaller than the gap width, or when the dynamic vibration of the member to be measured being rotated is large, restrictions on the outer diameter of the member to be measured and the size of the gap width have jumped. Therefore, accurate measurement of the shake amount can be performed.

  A first embodiment of the present invention will be described with reference to the drawings.

  Example 1 has an optical system that includes a light source, a lens system that guides light from the light source to a member to be measured, and a plurality of photodiodes that receive the light through the member to be measured. A measuring apparatus for measuring the position or shake amount of the member to be measured based on the amount of light received by a diode, wherein the plurality of photodiodes are used as shafts of the member to be measured when viewed in the optical axis direction of the optical system. All sides intersecting the center are straight lines, and at least one gap that is inclined with respect to the axial direction of the member to be measured is provided between the plurality of photodiodes. Sides that are positioned outward from the outer shape of the member and intersect the axis of the member to be measured other than the side parts of the photodiode forming the gap are parallel to the gap (gap axis thereof). Those that are configured not.

  Specifically, in Example 1, as shown in FIGS. 4 and 5, a gauge pin (round bar) as a member to be measured is measured using the photodiode shown in FIG. 1 (and FIG. 10A). In particular, it is useful when measuring a member to be measured having an extremely small diameter (outer diameter of 0.3 mm or less) while rotating at high speed.

  In the first embodiment, two photodiodes having the same area and polygonal shapes, more specifically, a pair of photodiodes having the same shape in the shape of a right triangle are provided, and the hypotenuses of the photodiodes are separated by a predetermined interval (gap width). The gaps are formed between the opposite hypotenuses by being spaced apart from each other. In other words, one photodiode including the region A and the region D in FIG. 1 and one photodiode including the region A and the region C are arranged to face each other.

  In FIG. 1, FIG. 1 (a) is a schematic explanatory view showing the relationship between a pair of photodiodes and a member to be measured as viewed in the optical axis direction of the optical system. Sides (sides sharing one vertex with the oblique side of the right-angled triangular photodiode) other than the side (the oblique side of the right-angled triangular photodiode) forming the gap among the sides intersecting with the heart are the gap. FIG. 1B is a graph showing a change in voltage difference depending on the position of the photodiode and the member to be measured.

  The measurement principle shown in FIG. 1 will be specifically described. When the measured member moves in the x direction (radial direction) and the measured member axial center position Xm changes, the voltage difference also changes due to the change in the area difference between receiving the light beams between the two photodiodes. Expression (1) represents the voltage difference by multiplying the area difference by the conversion coefficient Ke. Therefore, when the measured member axial center position Xm changes, the voltage difference corresponding to the position in the x direction (radial direction) of the measured member can be measured, and the maximum and minimum values of the voltage difference corresponding to the position can be measured. The voltage difference corresponding to the shake amount (the difference in voltage difference corresponding to the position) can be calculated from the difference.

  For example, when the shaft center position Xm of the member to be measured is at the center position of the photodiode (x-direction center position = L / 2 position) and is not rotating, or even if it is rotating, the shake amount is zero. The area difference between the respective photodiodes is zero, and thus the voltage difference is zero according to the calculation formula (1). If the position of the member to be measured changes, the voltage difference changes accordingly, and the position of the member to be measured can be known. If the member to be measured is rotating and the amount of deflection is not zero, the voltage difference changes as the shaft center position of the member to be measured moves in the x direction, and the maximum and minimum values of this voltage difference The voltage difference corresponding to the shake amount is calculated from the difference, and thus the shake amount that is the difference in the position in the x direction can be measured.

  Since the shake amount is obtained from the voltage difference using this principle, it can be calculated by applying the voltage difference or the like to Equation (2) obtained by modifying Equation (1). Here, if the voltage difference V applied to the equation (2) is a voltage difference corresponding to the shake amount, the calculated Xm is the shake amount of the measured member. For example, the voltage difference V applied to the equation (2) is the position. Xm calculated if the voltage difference corresponds to is the axial center position of the member to be measured. What is necessary is just to set it as the measuring apparatus which displays a position or a shake amount according to a use. In addition, L is the length of the photodiode, A is the height of the photodiode, r is the radius of the member to be measured, and Ke is a coefficient for converting a current generated according to the amount of received light per unit area of received light into a voltage. That is, it is a coefficient for converting the light receiving area into a voltage.

  The size (width) of the gap formed between the hypotenuses only needs to be separated as much as possible, and there is no theoretical limitation on the upper limit. The member to be measured may be disposed between the optical paths so that the member to be measured blocks the light beam from the light source (LED) over the entire height (A) of the photodiode when viewed in the optical axis direction of the optical system.

  In addition, the gap width is substantially different when the position of the photodiode shown in FIG. 1A is fixed in the x direction and moved in the y direction. Therefore, since the formula (2) can be applied as it is, there is no need to strictly adjust the gap width in actual production, which is very practical. In the case of adopting a form moved in the x direction, the relationship of equation (1) is broken, and therefore equation (2) cannot be applied. Therefore, measurement can be performed by applying a calculation equation according to the arrangement of the photodiodes.

  In addition, if the both end portions are positioned outward from the outer shape of the member to be measured in the optical axis direction view (gap front view) of the optical system, the gap passes through the midpoint of the gap width. The imaginary line orthogonal to the width direction may be set at any inclination angle. In this embodiment, it is set to 60 °.

  When the inclination angle of the gap axis with respect to the axial direction of the member to be measured is almost as close as 0 ° (when it is nearly parallel to the axial direction of the member to be measured), both ends of the gap are outside the outer shape of the member to be measured. In order to realize this, the height of the photodiode must be increased, which is not practical. If the photodiode is not set to a sufficient height, both end portions of the gap are positioned inward from the outer shape of the member to be measured, which is considered to be the range of the conventional example shown in FIG. The conventional problem is not solved. The inclination angle of the gap axis with respect to the axial direction of the member to be measured is practically | 30 | ° or more and | 90 | ° or less. The tilt angle may be tilted in any direction regardless of the direction in which the gap axis is tilted, and is expressed as an absolute value as described above. Further, the shape of the photodiode in the front view (the shape in the optical axis direction) may be any shape, and if it is a polygonal shape, it can be easily manufactured, which is advantageous in terms of production.

  In the first embodiment, light from a light source (LED) passes through a diaphragm (pinhole) to be collimated by a collimating lens 1 and is irradiated to a photodiode via a member to be measured. Further, in a state where the member to be measured is not disposed between the light path from the LED that is the light source to the photodiode, the entire region of the photodiode is set to be irradiated with the light beam from the LED. Although not shown in FIG. 5, the light emission amount of the LED is adjusted to a constant value by a photosensor and a light amount control circuit installed in the irradiation region of the lens.

  The photodiode generates a current according to the amount of light received, converts this current into a voltage by an amplifier and amplifies it, and measures the outer diameter, position and deflection of the gauge pin using various circuits. Hereinafter, a specific method for measuring the outer diameter, position, and deflection amount of the gauge pin will be described with reference to FIG.

  The outer diameter of the gauge pin can be obtained by adding a voltage corresponding to the area of the shadow portion blocked by the gauge pin of each photodiode by the adder circuit (3) from the signal from the amplifier (1). The A / D conversion circuit converts the obtained value from an analog value to a digital value.

  The amount of deflection of the gauge pin can be measured by measuring the position of the gauge pin and using various circuits based on the position information. That is, the voltage difference between the photodiodes is calculated from the signal from the amplifier (1) by the subtraction circuit (2). This voltage difference corresponds to the position of the gauge pin, and the maximum value holding circuit (4) ) A voltage difference corresponding to the maximum value (hereinafter abbreviated as “maximum value”) is held, and a voltage difference corresponding to the minimum value (of position) in the minimum value holding circuit (5) (hereinafter abbreviated as “minimum value”). ) Is held, and the value obtained by calculating the difference between the maximum value and the minimum value by the subtraction circuit (6) is the voltage difference V corresponding to the amount of deflection of the gauge pin (the difference in voltage difference corresponding to the position). ). Thereafter, the analog value is converted into a digital value by an A / D conversion circuit, and the voltage difference V corresponding to the shake amount is set to r, where r is a half value of the outer diameter of the gauge pin obtained as described above, and A more accurate shake amount can be obtained by applying r to the equation (2) for obtaining the shake amount Xm and calculating the shake amount by the shake amount acquisition calculation circuit (7). The obtained shake amount is displayed on the shake amount display.

  In other words, the gap axis between the photodiodes is inclined with respect to the axial direction of the member to be measured, and both ends of the gap are positioned outward from the outer shape of the member to be measured when viewed in the optical axis direction of the optical system. In the case of the arrangement, the equation (1) includes the radius r in the proportional term. Therefore, when the outer diameter of the member to be measured is changed, the axial center position of the member to be measured in the x direction shown in FIG. Even in such a case, the voltage difference V calculated by the calculation formula (1) changes. Therefore, the slope of the voltage difference shown in FIG. 1B changes, and calibration is required each time. However, since the outer diameter of the member to be measured can be measured as described above, by applying the radius r obtained from the outer diameter measured as described above to the equation (2), a value close to the theoretical value without performing calibration. Can be calculated.

  If the voltage difference corresponding to the position obtained by the subtraction circuit (2) is applied to the equation (2) instead of the voltage difference corresponding to the shake amount, the calculated Xm is the axial center position of the gauge pin. is there. It goes without saying that the position of the obtained gauge pin (member to be measured) can be applied to a measuring device for position measurement or position confirmation by displaying it on a display.

  In the conventional measuring apparatus shown in FIGS. 2 and 3 (the apparatus in which the two photodiodes are arranged apart from each other by the gap width and the gap axis is provided in parallel with the axial direction of the member to be measured), The radius r is included as a proportional term in the equation (3) for obtaining the voltage difference V or the equation (4) for obtaining the measured member axial center position (or the shake amount of the member to be measured) Xm obtained by modifying the equation (3). Absent. For this reason, even if the outer diameter of the member to be measured changes, there is an advantage that calibration is not necessary because the difference (outer diameter) does not affect the voltage difference V or the shake amount Xm. Since the gap may not be covered, the problem that accurate measurement cannot be performed is not solved. Specifically, in order to avoid the above-described problem, even if the gap width can be made as small as possible (gap width≈0 mm), in the position measurement, the outer diameter of the member to be measured is centered on the gap axis. Therefore, there is a problem that the amount of deflection cannot be measured so that the amount of deflection can exceed the amount of the outer diameter of the member to be measured.

  Further, in Example 1 (and Examples 2 and 3 to be described later), as described above, a configuration in which a pair of photodiodes having the same area and a right triangle shape and the same shape is provided (FIG. 10A), Any configuration may be adopted as long as it satisfies the conditions related to the gap, the photodiode, and the member to be measured, and two or more inclined gaps may be provided. What is necessary is just to calculate Xm with the calculation formula according to the structure of a photodiode.

  As the configuration of the photodiode, for example, the configurations shown in FIGS. 10B to 10D can be adopted. A symbol O in the figure is an imaginary line schematically showing the member to be measured. Further, the (horizontal) length of the photodiode only needs to be equal to the outer diameter of the member to be measured + α (the expected maximum deflection), and the height is preferably as low as possible (at least the length of the member to be measured). Less than). In general, when the measurement position in the axial direction of the member to be measured is different, the amount of vibration is different, the amount of deflection on the tip side is large, and the root side (side near the grasped portion of the member to be measured) tends to be small. For this reason, if the height of the photodiode is too high, the value of the shake amount in the axial direction of the member to be measured is averaged, and a desired value may not be obtained.

  In FIG. 10B, the area of the photodiode including the regions A and D is set to be the same as the area of the photodiode including the regions A and C. FIG. In the same manner as in (), based on the areas (a) to (e) delimited by the measured members of the respective photodiodes, the shake amount can be obtained in the same manner from the formula ((i + e)-(a + u)). Further, FIG. 10C is composed of three photodiodes, and the area of the photodiode including the area A and the area D is equal to the area of the photodiode including the area C and the area F. In addition, the sum of the areas of the two photodiodes (the sum of the area of the photodiode including the areas A and D and the area of the photodiode including the areas C and F), the area A, and the area E is included. The area of the photodiode is set to be the same. Based on the areas a to f, the shake amount can be obtained in the same manner from the calculation formula of (I + O)-((A + E) + (U + K)). FIG. 10D is composed of four photodiodes, and each photodiode is set to have the same area. Based on the areas (a) to (c), the shake amount can be obtained in the same manner from the calculation formula of ((I + F) + (U + K))-((A + O) + (E + K)). Note that it is advantageous in terms of production if the photodiodes have the same shape. Further, FIG. 10B can be easily realized by simply tilting a rectangular photodiode having a simple shape by a predetermined angle.

  That is, the configuration of the photodiode shown in FIGS. 10A to 10D exemplifies a highly practical configuration capable of carrying out the present invention, and FIGS. 10A to 10D are respectively produced. In consideration of the ease and cost, the combination of a plurality of photodiodes makes the area of the light receiving surface one-half of the total area of the light receiving surface.

  Since Example 1 is configured as described above, when measuring the deflection of the member to be measured based on the amount of light received by the photodiode by irradiating light from the LED while rotating the member to be measured, In a state where the member is not arranged between the light source LED and the photodiode, the light beam from the LED is set to be irradiated to the entire area of the photodiode, and the gap axis between the photodiodes is determined by the gap axis. Inclining with respect to the axial direction of the member to be measured, and arranging so that both ends of the gap are positioned outward from the outer shape of the member to be measured when viewed in the optical axis direction of the optical system. The amount of shake can be measured from the amount.

  Therefore, even when the outer diameter of the member to be measured is smaller than the gap width, or when the dynamic vibration of the member to be measured being rotated is large, restrictions on the outer diameter of the member to be measured and the size of the gap width have jumped. Therefore, accurate measurement of the shake amount can be performed.

  Therefore, Example 1 is an extremely practical measuring device that can measure the dynamic vibration of a small-diameter round bar that is attached to the spindle of a processing device used for cutting and rotates at a high rotational speed.

  A second embodiment of the present invention will be described with reference to the drawings.

  In the second embodiment, as shown in FIGS. 6 and 7, a telecentric optical system is provided between the member to be measured of the first embodiment and the photodiode. A gauge pin (round bar) is measured.

  The telecentric optical system is composed of an imaging lens (spherical lens) 2 and a stop, whereby an image of the member to be measured is formed toward the photodiode. When a telecentric optical system is added so that the distance between the telecentric optical system and the photodiode is fixed, the measured member forms an image on the photodiode even if the distance between the measured member and the telecentric optical system changes. Since the size of the image (shadow) does not change, it is possible to perform measurement more easily and accurately without strictly positioning the member to be measured in the optical axis direction. Therefore, the second embodiment can measure with higher accuracy than the first embodiment.

  The rest is the same as in Example 1.

  A specific third embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 8 and 9, the third embodiment is obtained by adding lenses 3 and 4 to the configuration of the second embodiment. A rotary cutting tool having a cutting edge is measured. In FIG. 9, the member to be measured is shown in a round bar shape for simplification.

  Here, the lens 3 is a cylindrical lens that focuses the light beam on a part of the member to be measured only in the axial direction of the member to be measured (the measurement range of the member to be measured is narrowed), and the lens 4 is the lens 3. It is a cylindrical lens that returns light with a narrow irradiation range to parallel light.

  By using the lens 3 that narrows the measurement range of the member to be measured, it becomes possible to irradiate the rotary cutting tool with substantially linear light that is substantially orthogonal to the axis of the rotary cutting tool, and the axial measurement range is as much as possible. Even with a drill or the like having a groove on the outer periphery, the amount of deflection can be measured accurately (the measured amount of deflection is the average value of the axial measuring range, so If the measuring range is wide, an error will occur if the drill has a groove on the outer periphery.)

  Hereinafter, a specific method for measuring the outer diameter, position, and runout amount of the rotary cutting tool will be described with reference to FIG.

  The outer diameter of the rotary cutting tool is maintained at its maximum value by adding the signal from the amplifier (1) to the voltage corresponding to the area of the shaded area blocked by the rotary cutting tool of each photodiode by the adder circuit (3). It can be obtained by holding the maximum value in the circuit (7). That is, in the case of a rotary cutting tool such as a drill, since there is a groove portion, it is necessary to maintain the maximum value of a portion with an outer periphery (a portion without a groove) unlike a gauge pin. The A / D conversion circuit converts the obtained value from an analog value to a digital value.

  The runout amount of the rotary cutting tool can be measured by measuring the position of the rotary cutting tool and using various circuits from the position information. That is, the voltage difference between the photodiodes is calculated from the signal from the amplifier (1) by the subtraction circuit (2), and this voltage difference corresponds to the position of the rotary cutting tool, and the maximum value is held by the subtraction circuit (9). A difference between a voltage corresponding to the maximum diameter held in the circuit (7) (hereinafter abbreviated as “maximum diameter”) and an instantaneous value is calculated, and the difference is compared with the comparison circuit (10) in the sample hold circuit (4). If the difference between the maximum diameter and the maximum diameter is larger than the predetermined reference value (when it is judged that there is no outer periphery such as a drill, ie, a groove), sampling is not performed and the previous value is held. When the difference from the maximum diameter is smaller than a predetermined reference value (when it is determined that there is an outer periphery such as a drill), sampling (output the voltage difference value as needed), the sampled voltage difference is Maximum value (position) in the maximum value holding circuit (5) The corresponding voltage difference (hereinafter abbreviated as “maximum value”) is held, and the minimum value holding circuit (6) holds the voltage difference (hereinafter abbreviated as “minimum value”) corresponding to the minimum value (position). The value obtained by calculating the difference between the maximum value and the minimum value by the subtraction circuit (8) is the voltage difference V corresponding to the runout amount of the rotary cutting tool (the difference in voltage difference corresponding to the position). is there. Thereafter, the analog value is converted into a digital value by an A / D conversion circuit, and further, a voltage difference V corresponding to the deflection amount is set to r, where r is a half value of the outer diameter of the rotary cutting tool obtained as described above. And r is applied to the equation (2) for obtaining the shake amount Xm, and the shake amount acquisition calculation circuit (11) calculates the more accurate shake amount. The obtained shake amount is displayed on the shake amount display. The predetermined reference value is a reference value that can be arbitrarily set due to the outer diameter of the rotary cutting tool.

  In Example 3, the measurement method is particularly useful, and a rotary cutting tool having a spiral chip discharge groove and a cutting edge on the outer periphery, such as a drill, is exemplified as a member to be measured. (Round bar) is also possible in the same way, and as described above, the measuring range in the axial direction of the gauge pin can be made as narrow as possible, so the amount of deflection at the desired position in the axial direction can be measured more accurately. It becomes possible to do.

  As described above, it is possible to accurately measure the deflection amount of a very small diameter drill or the like.

  The rest is the same as in Example 1.

  In addition, the sample and hold circuit in the third embodiment is merely an example, and is not limited to this configuration (without using the sample and hold circuit), and other methods may be used as long as the outer diameter of the rotary cutting tool can be obtained simultaneously. Needless to say, if the outer diameter can be correctly measured in advance by another measuring device, the shake can be measured with a simpler configuration.

Claims (7)

  An optical system including a light source, a lens system that guides light from the light source to a member to be measured, and a plurality of photodiodes that receive the light through the member to be measured; the amount of light received by the photodiode A measuring device for measuring a position or a shake amount of the member to be measured based on the optical axis of the optical system as viewed in the optical axis direction, the plurality of photodiodes being sides intersecting with the axis of the member to be measured All of the portions are straight, and at least one gap that is inclined with respect to the axial direction of the member to be measured is provided between the plurality of photodiodes. Both ends of the gap are outside the outer shape of the member to be measured. The side portion that is positioned in the direction and intersects the axis of the member to be measured other than the side portion of the photodiode that forms the gap is configured not to be parallel to the gap. Measuring apparatus according to claim.   The measuring apparatus according to claim 1, wherein each of the photodiodes is a polygonal photodiode when viewed in the optical axis direction of the optical system.   The measuring apparatus according to claim 1, wherein a telecentric optical system is provided between the member to be measured and the photodiode.   The measuring apparatus according to claim 1, wherein a lens that focuses the light beam only in the axial direction of the member to be measured is provided on a part of the member to be measured.   4. The measuring apparatus according to claim 1, wherein a lens that focuses the light beam only in an axial direction of the member to be measured on a part of the member to be measured, and the light beam parallel to the photodiode. 5. A measuring apparatus comprising a lens for irradiating as light.   The measuring apparatus according to claim 4, wherein the member to be measured is a rotary cutting tool.   The measuring apparatus according to claim 1, wherein two photodiodes having the same area and the same shape are provided.

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