Test Indicator

Abstract

To provide a test indicator 100 that tolerates replacement with a probe 210 differing in length to enable a range reachable by the probe 210 to be extended, and that tolerates an increase in rotation angle of the probe 210 and displays an accurate measurement value in a wide measurement range.SOLUTION: An arithmetic unit 400 of the test indicator 100 comprises: a probe length storage unit 420 that sets and stores a length of the probe 210; and a probe length correction arithmetic unit 400 that changes a conversion ratio with which a detection value by an encoder 340 is converted to a measurement value in accordance with the length of the probe 210 and corrects the measurement value. The arithmetic unit 400 includes: a rotation angle calculation unit 410 that determines a rotation angle αs[rad] of the probe 210 on the basis of the detection value by the encoder 340; and an arc chord error correction arithmetic unit 400 that corrects the measurement value by multiplying a sine value in which the rotation angle αs calculated by the rotation angle calculation unit 410 is taken as an argument.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a test indicator. [Background technology]

[0002] Test indicators (so-called lever-type dial gauges) are known (for example, Patent Document 1). The test indicator has a probe that is rotatably supported on the main body case. The probe has a contact at its tip. The test indicator then magnifies the displacement of the contact by using the principle of leverage. This makes the test indicator a high-precision, high-resolution measuring instrument.

[0003] Test indicators are used to measure minute displacements such as circular runout, total runout, flatness, and parallelism, and for precision comparison inspections such as the machining error of a machined product against a master work (or block gauge). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2008-309687 Summary of the Invention [Problem to be solved by the invention]

[0005] One thing to keep in mind when using a test indicator is that you should not replace the probe with one of a different length. This is because, due to the structural feature of magnifying the displacement (rotational displacement) of the contact point that rotates around the rotation axis using the principle of leverage, if the length of the contact point changes, the magnification ratio will change, and the displayed measurement value will be completely different from the displacement of the contact point. Therefore, in case you want to change the length of the contact point depending on the object to be measured or the measurement conditions, you must prepare models with different contact point lengths. Considering a manufacturing site where many measurement objects (workpieces) are inspected simultaneously in parallel, multiple models with different measurement probe lengths must be prepared.

[0006] Furthermore, test indicators are highly convenient measuring instruments that offer high accuracy, high resolution, and simple measurement, but the length of the probe is 15 to 20 mm, and the test indicator cannot measure deep areas on the inner surface of a hole with a depth exceeding 20 mm, for example. This is because a probe longer than 20 mm will bend, resulting in large measurement errors.

[0007] Furthermore, although test indicators can be used to inspect extremely small shapes, they cannot be used for measurements over a measurement range of 2 mm. This is because the probe rotates, and so over a small range, the arcuate orbit of the contact and its vertical displacement can be considered to be the same, but as the rotation angle increases, the discrepancy between the length of the arc and the vertical displacement becomes larger. Due to limitations on the probe length and rotation angle, the measurement range of the test indicator is limited to a maximum of 2 mm.

[0008] An object of the present invention is to provide a test indicator that allows the probe to be replaced with one of a different length, that allows the probe to have a longer reach, and that allows the probe to have a larger rotation angle, thereby displaying accurate measurement values ​​over a wide measurement range. [Means for solving the problem]

[0009] The test indicator of the present invention comprises: a measuring element having a contact at its tip that comes into contact with the surface of the object to be measured; a main body case that pivotally supports the probe; an encoder for detecting the amount of rotational displacement of the measuring element; a calculation unit that converts the detected value by the encoder into a displacement amount of the contact and calculates a measurement value; a display unit that displays the measurement value, The calculation unit a probe length storage unit that sets and stores the length of the probe; a measurement element length correction calculation unit that corrects the measurement value by changing a conversion ratio that converts the detection value by the encoder into the measurement value in accordance with the length of the measurement element. It is characterized by:

[0010] In one embodiment of the present invention, The calculation unit a rotation angle calculation unit that calculates a rotation angle αs [rad] of the probe based on the detection value by the encoder; an arc-sine error correction calculation unit that corrects the measurement value by multiplying the rotation angle αs calculated by the rotation angle calculation unit by a sine value having the rotation angle αs as an argument. It is preferable.

[0011] In one embodiment of the present invention, The calculation unit a probe length storage unit that sets and stores the length of the probe; a reference deflection error storage unit that stores, as a reference deflection error δsf, a deflection error of a reference probe actually measured when the reference probe has a predetermined reference length Gs; a deflection calculation unit that calculates an actual deflection error δcf, which is an actual deflection error, by correcting the reference deflection error δsf in accordance with the length of the probe; a deflection error correction calculation unit that corrects the measurement value by adding the actual deflection error δcf calculated by the deflection calculation unit. It is preferable.

[0012] In one embodiment of the present invention, The calculation unit a probe length storage unit that sets and stores the length of the probe; a reference forward deflection error storage unit that stores, as a reference forward deflection error δsf, a deflection error of the reference contact point actually measured when the reference contact point has a predetermined reference length Gs and is rotated in a direction in which the rotation angle of the reference contact point increases; an outgoing path deflection calculation unit that calculates an actual outgoing path deflection error δcf, which is an actual deflection error, by correcting the reference outgoing path deflection error δsf in accordance with the length of the probe; a reference return deflection error storage unit that stores, as a reference return deflection error δsb, a deflection error of the reference contact point actually measured when the reference contact point has a predetermined reference length Gs and is rotated in a direction in which the rotation angle of the reference contact point decreases; a return path deflection calculation unit that calculates an actual return path deflection error δcb, which is an actual deflection error, by correcting the reference return path deflection error δsb in accordance with the length of the probe; a deflection error correction calculation unit that corrects the measurement value by adding the actual forward deflection error δcf calculated by the forward deflection calculation unit when the detection value by the encoder changes in an increasing direction, and that corrects the measurement value by adding the actual backward deflection error δcb calculated by the backward deflection calculation unit when the detection value by the encoder changes in a decreasing direction. It is preferable.

[0013] The method for controlling a test indicator of the present invention comprises: 1. A method for controlling a test indicator comprising: a probe having a contact at its tip that contacts a surface of a measurement object; and a main body case that pivotally supports the probe, the method comprising: a rotation detection step of detecting a rotational displacement amount of the measuring element by an encoder; a calculation step of converting the detected value by the encoder into a displacement amount of the contact to calculate a measurement value; a display step of displaying the measurement value, The calculation step includes: a measuring point length storing step of setting and storing the length of the measuring point; and a probe length correction calculation step of correcting the measurement value by changing a conversion ratio for converting the value detected by the encoder into the measurement value in accordance with the length of the probe. It is characterized by:

[0014] In one embodiment of the present invention, The calculation step includes: a rotation angle calculation step of calculating a rotation angle αs [rad] of the probe based on the detection value by the encoder; an arc-sine error correction calculation step of correcting the measurement value by multiplying the rotation angle αs calculated in the rotation angle calculation step by a sine value having the rotation angle αs calculated as an argument. It is preferable.

[0015] In one embodiment of the present invention, The calculation step includes: a measuring point length storing step of setting and storing the length of the measuring point; a reference deflection error storage step of storing, as a reference deflection error δsf, a deflection error of the reference probe actually measured when the reference probe has a predetermined reference length Gs; a deflection calculation step of calculating an actual deflection error δcf, which is an actual deflection error, by correcting the reference deflection error δsf in accordance with the length of the probe; a deflection error correction calculation step of correcting the measurement value by adding the actual deflection error δcf calculated in the deflection calculation step. It is preferable.

[0016] In one embodiment of the present invention, The calculation step includes: a measuring point length storing step of setting and storing the length of the measuring point; a reference forward deflection error storage step of storing, as a reference forward deflection error δsf, a deflection error of the reference contact point actually measured when the reference contact point has a predetermined reference length Gs and is rotated in a direction in which the rotation angle of the reference contact point increases; an outward deflection calculation step of calculating an actual outward deflection error δcf, which is an actual deflection error, by correcting the reference outward deflection error δsf in accordance with the length of the probe; a reference return deflection error storage step of storing, as a reference return deflection error δsb, a deflection error of the reference contact point actually measured when the reference contact point has a predetermined reference length Gs and is rotated in a direction in which the rotation angle of the reference contact point decreases; a return path deflection calculation step of calculating an actual return path deflection error δcb, which is an actual deflection error, by correcting the reference return path deflection error δsb in accordance with the length of the probe; a deflection error correction calculation step of correcting the measurement value by adding the actual forward deflection error δcf calculated in the forward deflection calculation step when the detected value by the encoder changes in an increasing direction, and correcting the measurement value by adding the actual backward deflection error δcb calculated in the backward deflection calculation step when the detected value by the encoder changes in a decreasing direction. It is preferable. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is an external view of a test indicator. [Figure 2] FIG. 2 is a perspective view partially showing the internal structure of the test indicator. [Figure 3] FIG. 2 is a functional block diagram of a control circuit. [Figure 4] FIG. 10 is a diagram schematically showing the displacement Ls of the contact tip when the probe is rotated. [Figure 5] FIG. 10 is a diagram schematically showing the displacement Lc of the contact tip when the probe is rotated. [Figure 6] 10 is a diagram showing a schematic representation of the difference between the arc AB and the vertical displacement Lc. [Figure 7] FIG. 4 is a functional block diagram of a deflection correction unit. [Figure 8] FIG. 1 is a diagram illustrating an example of an error (deflection error δ) caused by the deflection of the probe. DETAILED DESCRIPTION OF THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be illustrated and described with reference to the reference numerals attached to the various elements in the drawings. (First embodiment) The basic structure of the test indicator 100 is well known, but will be briefly explained below. FIG. 1 is an external view of the test indicator of this embodiment. The test indicator 100 includes a main body case 110, a probe 210 rotatably supported by the main body case 110, and a display unit 120 that digitally displays the amount of rotational displacement of the probe 210.

[0019] The probe 210 is a generally elongated rod-like body that is exposed from an insertion hole 112 formed in the main body case 110 and is supported by a bearing member 114 provided in a bearing portion 113 of the main body case 110. The probe 210 has a contact 211 at its tip. Display unit 120 is formed in a flat, disk-like shape and is attached to main body case 110. Two switches (input means) 121 are provided on display unit 120. These switches 121 are used to turn the power on and off, switch displays, and also to input various commands and set values.

[0020] In this embodiment, a plurality of replacement probes 220 are prepared, and the probe can be replaced with a replacement probe 220. The replacement probes 220 may be made of a different material or may have a different shape or size of the contact 221, but here it is assumed that a plurality of probes 220 of different lengths are prepared. The probe 210 attached to the test indicator 100 by default will be referred to as the "reference probe 210." The length of the reference probe 210 will be referred to as the "reference length," and the reference length will be represented by Gs. In this embodiment, the reference length Gs is set to, for example, 10 mm, but the length Gs of the reference contact point 210 given by default depending on the model of the test indicator 100 may differ.

[0021] FIG. 2 is a perspective view partially showing the internal structure of test indicator 100. As shown in FIG. Inside main body case 110, there are arranged a first arm 310 connected to probe 210 so as to pivotally support the rotation axis of probe 210, a second arm 320 adjacent to first arm 310 on the opposite side of probe 210 and having a sector gear 321 at its end, a pinion 330 meshing with sector gear 321, and an encoder (rotary encoder) 340 capable of detecting the amount of rotation of pinion 330 as an electrical signal.

[0022] The rotary encoder 340 has a rotor (movable body) 341 and a stator (fixed body) 342, and detects the rotation angle of the rotor 341. The encoder may be an ABS (absolute) type that detects the absolute angle within one rotation, or an incremental type.

[0023] The operation of transmitting the oscillation of the probe 210 to the encoder 340 will now be briefly described. Assume that the probe 210 swings in the U direction in FIG. 2. Then, the first arm 310 rotates counterclockwise in FIG. 2 around the first shaft portion 311. At this time, the moving surface (distal moving surface) 312 of the first arm 310 moves downward in FIG. 2, and this downward movement of the distal moving surface 312 pushes the transmission pin (distal transmission pin) 323 of the second arm 320 downward in FIG. 2. Accordingly, the second arm 320 rotates counterclockwise around the second shaft portion 322. Then, as the second arm 320 moves downward, the pinion 330 rotates clockwise via the sector gear 321. The rotation of the pinion 330 is detected by the encoder 340.

[0024] Next, assume that the tracing element 210 is swung in the direction D. This causes the first arm 310 to rotate clockwise in FIG. 2 around the first shaft portion 311. At this time, the moving surface (proximal moving surface) 313 of the first arm 310 moves upward in FIG. 2, and the transmission pin (proximal transmission pin) 324 of the second arm 320 is pushed upward in FIG. 2. Accordingly, the second arm 320 rotates counterclockwise around the second shaft portion 322. Then, as the second arm 320 moves downward, the pinion 330 rotates clockwise via the sector gear 321.

[0025] That is, regardless of the swing direction of the probe 210, the second arm 320 rotates counterclockwise and the pinion 330 rotates clockwise.

[0026] The lever ratio is designed so that the magnification is the same when the probe 210 rotates in the U direction as when the probe 210 rotates in the D direction. This is because the fulcrum-to-point of action distance is determined by the relative positional relationship between the first shaft portion 311, the second shaft portion 322, the distal side transmission pin 323, and the proximal side transmission pin 324, and therefore these relative positions (relative distance) are determined so that the pinion 330 rotates the same amount in the forward and reverse directions. Since the lever ratio of the internal transmission mechanism 300 is fixed, there is a one-to-one relationship between the amount of rotation of the probe 210 and the amount of rotation of the pinion 330, ignoring the direction of rotation. The amount of rotation of the pinion 330 can be determined by detecting the amount of rotation of the probe 210 with the encoder 340 and multiplying it by a predetermined conversion ratio. If the length of the probe 210 is determined, the displacement of the contact 211 can be determined from the amount of rotation of the probe 210.

[0027] Since the second arm 320 rotates counterclockwise in response to the displacement (rotational movement) of the probe 210, a biasing means 350 is provided as a return force, which applies a biasing force in a direction that rotates the second arm 320 clockwise. This biasing means (e.g., a wire spring) 350 applies a return force that returns the probe 210 to its original position, and also applies a contact force (measuring force) when the contact 211 comes into contact with the object to be measured. When the second arm 320 is returned by the return force, the distal-side transmission pin 323 comes into contact with the distal-side moving surface 312, and the proximal-side transmission pin 324 comes into contact with the proximal-side moving surface 312, and the second arm 320 returns to a position (initial position) where the distal-side transmission pin 323 comes into contact with the distal-side moving surface 312.

[0028] Here, the "outbound journey" and "return journey" will be explained. When the contactor 211 comes into contact with the object to be measured, the case where the probe 210 rotates against the biasing force (returning force) is defined as the "forward path." In other words, whether the contactor 211 rotates counterclockwise (U direction) or clockwise (D direction), the direction in which the detection value of the encoder 340 increases when the probe 210 rotates (the contactor 211 is displaced) is defined as the "forward path." Conversely, when the probe 210 rotates in a direction in which it is pulled back by the biasing force (returning force), this is referred to as the "returning path." In other words, whether the probe 210 rotates counterclockwise (direction U) or clockwise (direction D), the direction in which the detected value of the encoder 340 decreases when the probe 210 rotates (the contact 211 is displaced) is the "returning path."

[0029] When continuously tracing and measuring the unevenness (or waviness) of the surface of the object to be measured, the contactor 211 moves up and down according to the surface shape of the object to be measured, and in this case, the displacement direction of the contactor 211 is a repetition of "forward" and "return." During the "outward movement," it can be expected that a nearly specified "measuring force" acts between the contact 211 and the object to be measured. During the "returning path," the measuring force between the contact 211 and the object to be measured is expected to be smaller than the specified "measuring force." Differences in measuring force result in differences in the force acting between the contact 211 and the object to be measured and in the frictional force within the internal transmission mechanism 300, and this causes differences in the measured values ​​(return error) between measurements made on the "forward path" and measurements made on the "return path," even when measuring unevenness of the same height. Furthermore, as the lengths of the probes 210 and 220 increase, the deflection of the probes 210 and 220 increases, and the return error also increases, making these errors no longer negligible.

[0030] Next, FIG. 3 is a functional block diagram for explaining the configuration of an internal control circuit. The control circuit is provided on a circuit board or integrated circuit chip arranged inside the main body case 110 or the display unit 120. The calculation unit 400 is composed of a CPU (Central Processing Unit), a ROM with a predetermined control program stored therein, and a RAM, and realizes the functions of the functional units shown in Fig. 3 by executing the predetermined program.

[0031] The calculation unit 400 includes a rotation angle calculation unit 410 , a probe length storage unit 420 , a probe length correction unit 430 , an arc-chord error correction unit 440 , a deflection correction unit 450 , and a measurement value calculation unit 460 .

[0032] Each functional unit will be explained in turn. The rotation angle calculation unit 410 calculates the rotation angle (α [rad]) of the probe 210 from the detection value of the encoder 340 (rotation angle calculation step). Because the lever ratio of the internal transmission mechanism 300 is fixed, the rotation angle (α [rad]) of the probe 210 is obtained by multiplying the rotation amount (αp) of the pinion 330 detected by the encoder 340 by a predetermined conversion ratio (Rr). The rotation angle of the probe 210 is expressed as α [rad].

[0033] αm=Rr×αp

[0034] The probe length storage unit 420 is a memory that stores the length information of the probe 210 . First, at the stage of product shipping, the length (reference length) Gs of the reference probe 210 is set and stored as a default value in the probe length storage unit 420 (probe length storage step). For example, the reference length Gs is set to 10 mm.

[0035] If the probe 210 is the default reference probe 210, the displacement Ls of the contact tip 211 is calculated as follows. FIG. 4 is a diagram schematically showing the displacement Ls of the contact piece 211 when the probe is rotated. The rotation angle αm [rad] of the probe 210 is previously calculated in the rotation angle calculation unit 410. Therefore, if the probe 210 is the default reference probe 210, the displacement Ls of the contact tip 211 is calculated as follows: Ls = Gs [mm] × αm [rad] (=Gs [mm] × Rr × αp [rad]) This can be obtained by:

[0036] In the case of the conventional test indicator 100, the measurement value calculation unit 460 calculates the displacement Ls of the contact 211 by multiplying the rotation angle αm (=Rr × αp [rad]) of the probe 210 obtained by the rotation angle calculation unit 410 by the reference length Gs, and outputs this Ls as a measurement value (displays it on the display unit 120) (display process).

[0037] The test indicator 100 of this embodiment allows the user to replace the probe 210 while the test indicator 100 is in use. When replacing the probe 210, the user sets the length Gc of the probe 220 to be used in the probe length storage unit 420 (probe length storage step). In this case, the user may directly input the value of the length Gc of the contact point 220. Alternatively, the types of interchangeable contact points 220 and their lengths Gc may be stored in advance as a selection menu in the contact point length storage unit 420, so that the user can select the type (length Gc) of the contact point from the selection menu when replacing the contact point. For example, the length Gc of the contact point 220 may be set to 20 mm, which is twice the reference length Gs.

[0038] The probe length correction unit 430 calculates a correction ratio so as to obtain a measurement value (displacement Lc of the contact 221) corresponding to the length Gc of the probe 220 currently in use. That is, if the probe 220 currently in use is replaced with the probe 210 having the length Gc, the correction ratio is Gc / Gs. Also, if the probe 210 remains at the default reference length Gs, that is, the current probe length Gc is the reference length Gs (Gc = Gs), the correction ratio is "1."

[0039] Here, FIG. 5 is a diagram that schematically shows the displacement Lc of the contact piece 221 when the probe 220 rotates. If the length of the currently used probe 220 is Gc, the displacement Lc of the contact 221 is Lc = (Gc / Gs) × Gs [mm] × αm [rad] (=(Gc / Gs)×Gs[mm]×Rr×αp[rad]) This can be obtained by:

[0040] If the correction is limited to the measurement element length, the measurement value calculation unit 460 calculates the displacement Lc of the contact 211 by multiplying the rotation angle αm (=Rr×αp [rad]) of the measurement element 220 by the reference length Gs and the measurement element length correction ratio (Gc / Gs) (measurement element length correction calculation step), and outputs this Lc as the measurement value (displays it on the display unit 120).

[0041] Here, the probe length correction unit 430 and the measurement value calculation unit 460 constitute a probe length correction calculation unit (probe length correction calculation step).

[0042] Next, the arc-chord error correction unit 440 will be described. The test indicator 100 of this embodiment allows the probes to be replaced with ones with longer lengths, which alone widens the measurement range. However, the rotation angle of the probes 210 and 220 can also be increased, aiming to widen the measurement range as much as possible. For example, if the measurement range could be expanded to 2 mm or more, the test indicator 100 would be able to easily inspect the shape of objects that could not be measured before. However, while the arc length of the arc AB and the vertical displacement Lc can be considered to be the same when the rotation angle αm of the probe 210 is small, as the rotation angle αm of the probe 210 increases, the deviation between the two becomes non-negligible. Figure 6 is a diagram schematically showing the difference between the arc AB and the vertical displacement Lc. Therefore, in this embodiment, a function for correcting the arc chord error is implemented.

[0043] The arc chord error correction unit 440 corrects the arc trajectory of the contact piece 211 to a vertical displacement of the contact piece 211 using the probe rotation angle αm [rad] calculated by the rotation angle calculation unit 410 . The arc-sine error correction unit 440 calculates the sine value (=Sin(αm)) of the probe rotation angle αm [rad] every moment as a correction coefficient, and supplies it to the measurement value calculation unit 460. The measurement value calculation section 460 uses this sine value (=Sin(αm)) instead of the rotation angle αm [rad] of the probe 210 to find the displacement Lc of the contact piece 211 (arc-chord error correction calculation step). Lc = (Gc / Gs) × Gs [mm] × Sin(αm) (=(Gc / Gs)×Gs[mm]×Sin(Rr×αp))

[0044] Here, the arc-chord error correcting section 440 and the measurement value calculating section 460 constitute an "arc-chord error correction calculating section (arc-chord error correction calculating step)."

[0045] In this way, in this embodiment, by performing a correction calculation process (arc-sinus error correction calculation process) using a sine value (= Sin(αm)), it is possible to provide accurate measurement values ​​while allowing the rotation angle αm of the probes 210, 220 to increase, and the measurement range of the test indicator 100 can be made significantly wider than that of conventional models.

[0046] Next, the deflection correcting section 450 will be described. Since the probes 210 and 220 can be considered to have a long, thin rod-like shape, when a force (a reaction force to the measuring force) is applied from the measurement object to the contacts 211 and 221, the probes 210 and 220 will bend. The rotation angle αp of the probes 210 and 220 will be smaller by the amount of this bending, and an error will occur in the measurement value (the height of the unevenness of the measurement object) by that amount. The error caused by this probe bending will increase as the probes 210 and 220 become longer. If replacement with a longer probe 220 is permitted, the effect of the bending error will become significant. Therefore, this embodiment is equipped with a function to correct the bending error.

[0047] FIG. 7 is a functional block diagram of the deflection correction unit 450. As shown in FIG. The deflection correction unit 450 includes a reference forward deflection error storage unit 451 , a forward deflection calculation unit 452 , a reference backward deflection error storage unit 453 , a backward deflection calculation unit 454 , and a rotation direction determination unit 455 .

[0048] The reference forward deflection error storage unit 451 and the reference backward deflection error storage unit 453 are storage units that store the deflection amount actually measured for the reference contact point 210. For example, by measuring a known height gauge with a standard contact point 210 having a reference length Gs (e.g., 10 mm) attached to the test indicator 100, the error (deflection error δs) between the height gauge and the actual measurement value can be obtained. For example, Fig. 8 is a diagram that schematically illustrates the error (deflection error δ) due to the deflection of the contact point 210.

[0049] As mentioned above, there is a difference in deflection error between measurements made on the "forward path" and measurements made on the "return path" (return error). Therefore, the deflection error δs obtained when the gauge is measured on the forward path is set as the reference forward path deflection error δsf, and the value of the reference forward path deflection error δsf is set and stored in the reference forward path deflection error storage unit 451 (reference forward path deflection error storage step). The deflection error δs obtained when the gauge is measured on the return path is set as the reference return path deflection error δsb, and the value of the reference return path deflection error δsb is set and stored in the reference return path deflection error storage unit 453 (reference return path deflection error storage step). (For example, by going back and forth on a gentle slope with a known gradient, the actual measurement error between the "outbound" and "return" journeys can be obtained.)

[0050] Next, the calculations performed by the forward deflection calculation unit 452 and the backward deflection calculation unit 454 will be described. The amount of deflection of the probe 210 varies depending on the length of the probe 210 . Since the test indicator 100 of this embodiment allows the probe 210 to be replaced, it is necessary to correct the amount of deflection according to the length of the probe. Generally speaking, the deflection of a rod is proportional to the load at the tip and to the cube of its length. In the case of test indicator 100, the measuring force applied to the tips of the probes 210 and 220 of test indicator 100 is inversely proportional to the length of the probes 210 and 220, and therefore, when only the probe length and measuring force (load) are considered, the amount of deflection of the probes 210 and 220 of test indicator 100 is proportional to the square of the length of the probes 210 and 220. In other words, if the length of the probe 220 after replacement is Gc for the probe 210 with a reference length Gs, the actual deflection error δc according to the length Gc of the probe 220 is as follows:

[0051] δc=δs×(Gc / Gs) 2

[0052] However, the probes 210 and 220 are not round rods of uniform thickness, but have a distinctive shape, such as a taper that narrows toward the tip. Therefore, it cannot be said that the amount of deflection is perfectly proportional to the square of the length. In practice, it is desirable to actually measure the amount of deflection of each probe, obtain the actual measured value for each probe, and derive a correction polynomial that relates the length and amount of deflection.

[0053] In response to the replacement of the probe 210 with the probe 220 having the length Gc, the forward deflection calculation unit 452 calculates the forward deflection δcf (=δsf×(Gc / Gs)) obtained by converting the reference forward deflection error δsf set and stored in the reference forward deflection error storage unit 451 in accordance with the probe length Gc. 2) is calculated (outward deflection calculation process) and stored. In response to the replacement of the probe 210 with the probe 220 having the length Gc, the return path deflection calculation unit 454 converts the reference return path deflection error δsb set and stored in the reference return path deflection error storage unit 453 in accordance with the probe length Gc to obtain a return path deflection δcb (=δsb × (Gc / Gs) 2 ) is calculated (return deflection calculation process) and stored.

[0054] The rotation direction determination unit 455 determines whether the rotation direction (movement direction) of the probe 210 is "forward" or "returning," and determines whether the forward deflection δcf or the return deflection δcb should be used as the deflection correction value. For example, the rotation direction determination unit 455 calculates the derivative (difference per unit time) of the rotation angle of the probes 210 and 220 obtained by the rotation angle calculation unit 410, and if this value is positive, determines that the rotation direction (movement direction) of the probes 210 and 220 is "forward." Conversely, if the derivative (difference per unit time) of the rotation angle of the probes 210 and 220 obtained by the rotation angle calculation unit 410 is negative, the rotation direction determination unit 455 determines that the rotation direction (movement direction) of the probes 210 and 220 is "returning." When the differential (difference per unit time) of the rotation angle of the probe 210 is zero, it is considered to be the "outward path."

[0055] The rotation direction determination unit 455 determines the rotation direction (movement direction) of the probes 210 and 220 from moment to moment, and outputs the deflection error δc to the measurement value calculation unit 460 by switching between the "forward path deflection δcf" and the "return path deflection δcb" depending on whether the probes are in the "forward path" or "return path."

[0056] The measurement value calculation unit 460 calculates a corrected measurement value by taking into account the reference length Gs, the probe length correction ratio (Gc / Gs), the sine value of the rotation angle αp, and also the deflection error δc (deflection error correction calculation process).

[0057] Lc=(Gc / Gs)×Gs[mm]×Sin(αm)+δc

[0058] Here, the rotation direction determination unit 455 and the measurement value calculation unit 460 constitute a deflection error correction calculation unit (deflection error correction calculation step).

[0059] As described above, the test indicator 100 of this embodiment allows the probes 210, 220 to be replaced with probes of different lengths. In this case, by performing a correction calculation to account for the error factors caused by the longer length of the probe, it is possible to maintain sufficiently high accuracy and resolution. In addition, by performing a correction calculation process using a sine value (= Sin(αm)), accurate measurement values ​​can be obtained while allowing for a larger rotation angle αm of the probes 210 and 220. Therefore, for example, for deep parts of the inner surface of a hole having a depth of more than 20 mm, the probe length can be replaced with a longer one exceeding 20 mm, making it possible to create a test indicator 100 that can perform shape inspection over an expanded measurement range (e.g., 2 mm or more). Furthermore, since the user can use one test indicator 100 by switching between multiple probes 210, 220, the cost of procuring and storing the measuring device can be significantly reduced.

[0060] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the invention. In the above embodiment, the deflection error correction is performed by distinguishing between the measurement on the "forward pass" and the measurement on the "return pass," and by changing the correction value applied in each case. This is considered to be necessary when continuously measuring the shape of an object, such as in scanning measurement. On the other hand, when measuring distant measurement points one by one, or when measuring slowly even in the case of scanning measurement, the specified measuring force acts firmly between the contact and the object to be measured, so in this case it is considered unnecessary to distinguish between the "forward pass" and the "return pass." In this case, the "forward pass" is always considered, and the reference return pass deflection error storage unit 453, the return pass deflection calculation unit 454, and the rotation direction determination unit 455 may be omitted. [Explanation of symbols]

[0061] 100 Test Indicators 110 Main unit case 112 Insertion hole 113 Bearing section 114 Bearing parts 120 Display section 121 Switch (input means) 210, 220 probe 211, 221 contacts 300 Internal Transmission Mechanism 310 First Arm 311 First shaft 312 Distal moving surface 313 Proximal moving surface 320 Second Arm 321 Sector Gear 322 Second shaft 323 Distal Transmission Pin 324 Proximal Transmission Pin 330 Pinion 340 encoder 341 Rotor (moving body) 342 Stator (fixed body) 350 biasing means (spring) 360 Stopper (fixing pin) 400 Arithmetic section 400 Arc string error correction calculation section 410 Rotation angle calculation unit 420 Probe length memory section 430 Probe length correction unit 440 Arc chord error correction section 450 Deflection compensation unit 451 Reference forward deflection error memory unit 452 Outward deflection calculation section 453 Reference return deflection error memory unit 454 Return deflection calculation section 455 Rotation direction determination unit 460 Measurement value calculation unit.

Claims

1. A measuring element, a main body case that pivotally supports the probe so that the probe can be rotated and displaced; an encoder for detecting the amount of rotational displacement of the measuring element; a calculation unit that converts the detected value by the encoder into a displacement amount of the contact and calculates a measurement value; a display unit that displays the measurement value, the measuring element is a generally elongated rod-like body, and has a spherical contact at its tip, which contacts the surface of the object to be measured, and the base end side of the measuring element is pivotally supported on the main body case, The calculation unit a rotation angle calculation unit that calculates a rotation angle αs [rad] of the probe based on the detection value by the encoder; an arc-sine error correction calculation unit that corrects the measurement value by multiplying the rotation angle αs calculated by the rotation angle calculation unit by a sine value having the rotation angle αs calculated by the rotation angle calculation unit as an argument.

1. A test indicator comprising:

2. 2. The test indicator of claim 1, The calculation unit further a probe length storage unit that sets and stores the length of the probe; a measurement element length correction calculation unit that corrects the measurement value by changing a conversion ratio that converts the detection value by the encoder into the measurement value in accordance with the length of the measurement element.

1. A test indicator comprising:

3. A method for controlling a test indicator comprising: a probe that is a generally elongated rod-like body having a spherical contact at its tip that contacts the surface of an object to be measured; and a main body case that pivotally supports a base end side of the probe so that the probe can be rotated and displaced, a rotational displacement amount detecting step of detecting the rotational displacement amount of the measuring piece by an encoder; a calculation step of converting the detected value by the encoder into a displacement amount of the contact to calculate a measurement value; a display step of displaying the measurement value, The calculation step includes: a rotation angle calculation step of calculating a rotation angle αs [rad] of the probe based on the detection value by the encoder; an arc-sine error correction calculation step of correcting the measurement value by multiplying the rotation angle αs calculated in the rotation angle calculation step by a sine value having the rotation angle αs calculated as an argument.

10. A method for controlling a test indicator, comprising:

4. 4. The method for controlling a test indicator according to claim 3, The calculation step further comprises: a measuring point length storing step of setting and storing the length of the measuring point; and a probe length correction calculation step of correcting the measurement value by changing a conversion ratio for converting the value detected by the encoder into the measurement value in accordance with the length of the probe.

10. A method for controlling a test indicator, comprising:

Images