High-precision linear displacement sensor and measuring method thereof

Abstract

The invention discloses a high-precision linear displacement sensor and a measurement method thereof, and the method comprises the following steps: S1, attaching a probe to a to-be-measured workpiece, and obtaining the rotation angle p degree of the probe, the inclination angle X degree of the probe in the X direction, and the inclination angle Y degree of the probe in the Y direction when the to-be-measured workpiece moves; and S2, calculating a height change value H of the workpiece to be measured through a formula (1). Compared with the prior art, on the basis that the rotating angle p degree of the measuring needle, the inclination angle X degree of the measuring needle in the X direction and the inclination angle Y degree of the measuring needle in the Y direction are obtained, after the Abbe error is corrected through the formula (1), the measuring result is converted into the absolute variation from the relative variation, and compared with a traditional lever meter, the measuring precision is higher. And secondly, the linear displacement sensor provided by the invention has lower requirements on pose placement when in use, so that the learning cost of a beginner in use is further reduced, and the reliability of a measurement result and the working efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of linear displacement sensor manufacturing, and in particular to a high-precision linear displacement sensor and a measuring method thereof. Background Art

[0002] Lever gauges are measuring instruments widely used in mechanical production and processing scenarios such as shape inspection, tolerance control, and wear detection. Traditional lever gauges have the following defects:

[0003] 1. Unable to correct Abbe error: Due to design limitations, traditional lever meters only use a pure mechanical lever structure to amplify the probe displacement, and do not have the structure and ability to correct the Abbe error;

[0004] 2. Difficulty in data recording: Traditional lever meters usually do not have digital functions, and data recording and analysis need to rely on manual operations, which is not conducive to large-scale data processing and modern production needs.

[0005] The existing digital lever meter also has the following defects:

[0006] 1. Higher cost: The manufacturing process of digital lever meters is complex and includes electronic components and sensors, so the cost is usually higher than that of traditional lever meters. For some small and medium-sized enterprises with limited budgets, large-scale application may not be possible;

[0007] 2. Unable to correct Abbe error: Since it uses the same design principle as the traditional lever meter, it is also unable to consider the error caused by different measurement postures on the measurement results, that is, it is impossible to correct the Abbe error.

[0008] Fundamentally, whether it is a traditional lever meter or an existing digital lever meter, its algorithm design still uses the measurement principle of a traditional lever meter, so it is impossible to compensate for the Abbe error. Therefore, the measurements of both can only be relative deviation measurements, not absolute deviation measurements. Summary of the invention

[0009] 1. Technical issues to be resolved

[0010] Based on this, the present invention proposes a high-precision linear displacement sensor and a measurement method thereof, so as to solve the problem that the existing lever meter cannot correct the Abbe error.

[0011] (II) Technical solution

[0012] In order to overcome the above-mentioned problems or at least partially solve the above-mentioned problems, the present invention provides a high-precision linear displacement sensor, comprising a rotating shaft rotatably arranged in a shell, a measuring needle being fixed to one end of the rotating shaft, an angle encoder being connected to the other end of the rotating shaft, and a posture sensor being also provided on the rotating shaft between the angle encoder and the measuring needle.

[0013] Preferably, the measuring needle is threadedly connected to the rotating shaft.

[0014] Preferably, the posture sensor is fixed on the rotating shaft by bonding.

[0015] Preferably, it also includes a display screen and a controller, and the controller is communicatively connected to the display screen, the angle encoder and the posture sensor respectively.

[0016] The present invention also provides a method for measuring the high-precision linear displacement sensor as described above, comprising the following steps:

[0017] S1: The stylus is attached to the workpiece to be measured. When the workpiece to be measured moves, the stylus rotation angle p°, the stylus inclination angle X° in the X direction, and the stylus inclination angle Y° in the Y direction are obtained;

[0018] S2: Then calculate the height change value H of the workpiece to be measured by the following formula (1):

[0019] H=L×sinP°×cosY°×sin ( 90-X ) °+(LL×cos P°)×sinX° (1)

[0020] Where L is the length of the probe.

[0021] Preferably, after step S2, the method further includes the following step: displaying the height change value H of the workpiece to be measured on a display screen.

[0022] Preferably, in step S1, the angle p° of rotation of the measuring needle is obtained by an angle encoder.

[0023] Preferably, in step S1, the inclination angle X° of the measuring needle in the X direction and the inclination angle Y° of the measuring needle in the Y direction are obtained by a posture sensor.

[0024] Preferably, when the inclination angle of the measuring needle in the Y direction is 0°, the height change value H of the workpiece to be measured can also be calculated by the following formula (2):

[0025]

[0026] Preferably, in step S2, the specific steps of obtaining formula (1) are:

[0027] S21: The stylus rotates around point A, and the stylus is connected to the reference plane at point B. The inclination angle of the stylus in the X direction is X°. When the inclination angle of the stylus in the Y direction is 0°, the stylus is connected to the plane to be measured at point E'; when the inclination angle of the stylus in the Y direction is Y°, the stylus rotates at an angle of P°, and the stylus is connected to the plane to be measured at point E;

[0028] S22: Draw EC through point E, perpendicular to AB at point C, and split the projection height H of BE into the sum of the projection heights of BC and CE;

[0029] S23: The projection height of CE is H 1 , H 1 Obtained by the following formula (3):

[0030] H 1 =L×sinP°×cosY°×sin(90-X)° (3)

[0031] S24: The projection height of BC is H 2 , H 2 Obtained by the following formula (4):

[0032] H 2 =(LL×cosP°)×sinX° (4).

[0033] (III) Beneficial effects

[0034] Compared with the prior art, the principle algorithm and structural design of the present invention are different from the existing traditional lever meter technology. Based on the obtained angle p° of rotation of the measuring needle, the inclination X° of the measuring needle in the X direction and the inclination Y° of the measuring needle, the present invention corrects the Abbe error through formula (1), so that the measurement result is converted from a relative change to an absolute change. Compared with the traditional lever meter, the measurement accuracy of the present invention is higher, and it can be integrated into intelligent manufacturing. Compared with the existing digital lever meter, the cost is lower. Secondly, the linear displacement sensor provided by the present invention has lower requirements on posture placement when in use, which further reduces the learning cost for beginners and helps to improve the reliability of measurement results and work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0036] Figure 1 Schematic diagram of the position and posture of the measuring needle of the present invention;

[0037] Figure 2 It is a schematic diagram of the measuring needle of the present invention when the inclination angle in the Y direction is 0°;

[0038] Figure 3 A schematic diagram of eliminating Abbe error of the present invention;

[0039] Figure 4 It is a statistical diagram of the measured indication values ​​of the linear displacement sensor of the present invention;

[0040] Figure 5 This is a statistical diagram of the measured values ​​of a traditional lever meter;

[0041] Figure 6 It is a structural schematic diagram of the present invention;

[0042] Figure 7 It is a perspective structural schematic diagram of the present invention;

[0043] Figure 8 It is a front view of the present invention;

[0044] Fig. 9 It is a partial structural schematic diagram of the present invention.

[0045] Description of reference numerals:

[0046] 1. Housing, 2. Rotating shaft, 3. Probe, 4. Angle encoder, 5. Posture sensor, 6. Display screen, 7. Rear end plate, 8. Front end cover, 9. Battery, 21. Plane, 22. Connecting hole, 100. Clamp, 200. Support arm. DETAILED DESCRIPTION

[0047] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0048] The measurement process of the traditional lever meter is as follows: after placing the measuring needle 3 on the plane to be measured, as the workpiece / instrument moves, the height change of the plane will cause the measuring needle 3 to rotate, so that the height change of the plane to be measured is converted into the angle change of the measuring needle 3.

[0049] Initially, the length of the stylus 3 is 11.2 mm (standard part), the rotation angle P read by the angle encoder 4 is 2.000°, and the measurement is performed under the assumption that the X and Y axis posture variables of the stylus 3 are both 0, that is, the stylus 3 is completely horizontal, and the diameter of the small ball at the top of the stylus 3 is infinitely close to 0. At this time, the height change value measured is 0.390874 mm.

[0050] The influence of the top ball diameter on the change of plane height is investigated by introducing the top ball diameter to 0.1mm, and other conditions remain unchanged (the rotation angle P is still 2.000°). At this time, the height change value measured is 0.390874mm, which is consistent with the case when the ball diameter is 0mm. Since the ball is always tangent to the plane to be measured, the distance between the top center of the probe 3 and the plane to be measured before and after rotation is always equal to the ball diameter. The height difference obtained by subtracting the height difference before and after can eliminate the variable of the ball diameter, so the change of the ball diameter has no effect on the measurement result.

[0051] The axial inclination angle of the rotating shaft 2 of the measuring needle 3, i.e., the X-axis posture inclination angle, is set to 15°, and other conditions remain unchanged (the rotation angle P is still 2.000°). At this time, the height change value measured is 0.379321mm, which is different from when the X-axis inclination angle is 0°. Therefore, the measurement accuracy of the linear displacement sensor is affected by the X-axis posture inclination angle.

[0052] The radial inclination angle of the rotating shaft 2 of the measuring needle 3, that is, the Y-axis posture inclination angle, is set to 10°, and other conditions are kept unchanged (the rotation angle P is still 2.000°). Under the premise of keeping the height change value at 0.379321mm, the measured rotation angle P becomes 2.0306°, which is different from when the Y-axis inclination angle is 0°. Therefore, the measurement accuracy of the linear displacement sensor is affected by the Y-axis posture inclination angle.

[0053] See attached Figure 6 and attached Figure 7 This embodiment provides a high-precision linear displacement sensor, including a rotating shaft 2 rotatably arranged in a shell 1, a measuring needle 3 is fixed to one end of the rotating shaft 2, an angle encoder 4 is connected to the other end of the rotating shaft 2, and a posture sensor 5 is also provided on the rotating shaft 2 between the angle encoder 4 and the measuring needle 3.

[0054] An implementation manner of the measuring needle 3 : the measuring needle 3 is threadedly connected to the rotating shaft 2 so as to be compatible with an existing universal standard measuring needle 3 .

[0055] As another embodiment of the present invention: Fig. 9 , the posture sensor 5 is fixed on the rotating shaft 2 by bonding. Specifically, a plane 21 is provided in the middle of the rotating shaft 2, and the posture sensor 5 is fixed on the plane 21 by gluing. The use of gluing can reduce costs and save internal space while ensuring stable use; secondly, since the lever table measurement is very sensitive to load, the use of gluing can also prevent the rotating shaft 2 material from being deformed or cracked by external influences; furthermore, the stress is dispersed by gluing multiple connection points together, which can also improve the overall structural strength.

[0056] As another embodiment of the present invention: this embodiment further includes a display screen 6 and a controller, and the controller is respectively connected to the display screen 6, the angle encoder 4 and the posture sensor 5. The measurement results are directly displayed on the display screen 6, which saves the time-consuming manual reading process and avoids the error caused by naked eye observation.

[0057] Specifically, a connecting hole 22 is provided on the rotating shaft 2, and the connecting hole 22 is coaxially arranged with the rotating shaft 2. The rotating rod of the angle encoder 4 is inserted into the connecting hole 22 and then fixed by bonding.

[0058] As another embodiment of the present invention: the shell 1 is fixed with a rear end plate 7, the battery 9 is installed in the rear end plate 7, the angle encoder 4 is arranged between the rear end plate 7 and the rotating shaft 2, and the tail of the angle encoder 4 is inserted into the rear end plate 7 and then fixed by bonding.

[0059] As another embodiment of the present invention: Figure 8 The housing 1 is also fixed with a front end cover 8, and the rotating shaft 2 is rotatably connected to the front end cover 8.

[0060] This embodiment further includes a clamping member 100, which is clamped on the housing 1, and the clamping member 100 and the measuring needle 3 are respectively arranged at two ends of the housing 1. Specifically, the clamping member 100 is clamped into the housing 1 and then fixed by bonding.

[0061] Specifically, the display screen 6 is fixed to the housing 1 by screws.

[0062] As another embodiment of the present invention: a support arm 200 is fixed on the rotating shaft 2 , a screw hole matching the measuring needle 3 is provided on the support arm 200 , and the measuring needle 3 is threadedly connected to the support arm 200 .

[0063] The present invention also provides a measurement method of a high-precision linear displacement sensor as described above, comprising the following steps:

[0064] S1: The stylus 3 is attached to the workpiece to be measured. When the workpiece to be measured moves, the rotation angle p° of the stylus 3, the inclination angle X° of the stylus 3 in the X direction, and the inclination angle Y° of the stylus 3 in the Y direction are obtained; refer to the attached Figure 1 The angle between the stylus 3 and the reference plane is the inclination angle X° of the stylus 3 in the X direction, and the angle between the rotation axis 2 and the reference plane is the inclination angle Y° of the stylus 3 in the Y direction.

[0065] S2: Then calculate the height change value H of the workpiece to be measured by the following formula (1):

[0066] H=L×sinP°×cosY°×sin(90-X)°+(LL×cosP°)×sinX° (1)

[0067] Wherein, L is the length of the measuring needle 3.

[0068] As another embodiment of the present invention: after step S2, the following step is also included: displaying the height change value H of the workpiece to be measured on the display screen 6, so that the height change value of the workpiece to be measured can be obtained in real time, and it is also convenient to connect with other digital devices.

[0069] An implementation method of obtaining the rotation angle p° of the measuring needle 3: In step S1 , the rotation angle p° of the measuring needle 3 is obtained by the angle encoder 4 .

[0070] An implementation method of obtaining the inclination angle X° and the inclination angle Y° of the stylus 3: In step S1, the inclination angle X° of the stylus 3 in the X direction and the inclination angle Y° in the Y direction are obtained by the posture sensor 5. Specifically, the posture sensor 5 is a six-axis posture inclinometer.

[0071] In formula (1), when the inclination angle of the probe 3 in the Y direction is 0°, the height change value H can be obtained by the following formula:

[0072] H=L×sin P°×sin(90-X)°+(LL×cos P°)×sinX°

[0073] As another embodiment of the present invention: Figure 2 When the inclination angle of the stylus 3 in the Y direction is 0°, the height change value H of the workpiece to be measured can also be calculated by the following formula (2):

[0074]

[0075] When the inclination angle of the stylus 3 in the Y direction is 0, formula (2) is simpler than formula (1) and has a higher calculation efficiency.

[0076] As another embodiment of the present invention: in step S2, refer to the attached Figure 3 , the specific steps to obtain formula (1) are:

[0077] S21: the stylus 3 rotates around point A, point A is located on the axis of the rotating shaft 2, the stylus 3 is connected to the reference plane at point B, the inclination angle of the stylus 3 in the X direction is X°, when the inclination angle of the stylus 3 in the Y direction is 0°, the stylus 3 is connected to the plane to be measured at point E'; when the inclination angle of the stylus 3 in the Y direction is Y°, the rotation angle of the stylus 3 is P° (P tilt), and the stylus 3 is connected to the plane to be measured at point E;

[0078] S22: Draw EC through point E, perpendicular to AB at point C, and split the projection height H of BE into the sum of the projection heights of BC and CE;

[0079] S23: The projection height of CE is H 1 , H 1 Obtained by the following formula (3):

[0080] H 1 =L×sinP°×cosY°×sin(90-X)° (3)

[0081] Specifically, the process of obtaining formula (3) is as follows:

[0082] AB=AE=AE'=L

[0083] CE=AE×sinP°=L×sinP°

[0084] Again, since plane AE'B is the rotation plane of the stylus 3 when the Y-axis inclination angle is 0°,

[0085] ∴Easy to prove: plane ABE'⊥EE'

[0086] ∴ Connect CE', CE'⊥EE'

[0087] ∴CE'=CE×cosY°=L×sinP°×cosY°

[0088] ∴H(CE')=CE'×sin(90-X)°=L×sinP°×cosY°×sin(90-X)°

[0089] Where H(CE') is the projection height of CE.

[0090] S24: The projection height of BC is H 2 , H 2 Obtained by the following formula (4):

[0091] H 2 =(LL×cosP°)×sinX° (4)

[0092] Specifically, the process of obtaining formula (4) is:

[0093] ∵AC=L×cosP°

[0094] ∴C=LL×cosP°

[0095] ∴H(BC)=(LL×cosP°)×sinX°

[0096] Then the distance from the reference distance to the plane to be measured is:

[0097] L×sinP°×cosY°×sin(90-X)°+(LL×cosP°)×sinX°

[0098] Dial gauge calibration test

[0099] The linear displacement sensor (digital lever meter) using the measurement method provided by the present invention and the traditional lever meter are selected to measure the same test area. The worktable is ensured to move parallel by turning the hand wheel of the machining center, and then readings are taken once at intervals of 0.05mm, and a total of 17 points of data (full range 0.8mm) are collected and a calibration indication curve is drawn. Figure 4 The data measured by the linear displacement sensor of the present invention has a single-vector range indication error of 4 μm, a double-vector range indication error of 4 μm, and a return error of 1 μm. Figure 5The data are measured by a traditional lever meter, with a single-vector range indication error of 10μm, a dual-vector range indication error of 10μm, and a return error of 3μm.

[0100] The correlation coefficients of the forward and reverse travel measurement results of the two meters are calculated respectively:

[0101] R 正 =0.9108, R 反 =0.8772. From the correlation coefficient, we can see that the trends of the indication curves of the two lever meters are highly similar, which proves that the algorithm of the digital lever meter is feasible.

[0102] The principle algorithm and structural design of the present invention are different from the existing traditional lever meter technology. Based on the obtained rotation angle p° of the probe 3, the inclination angle X° of the probe 3 in the X direction and the inclination angle Y° of the probe 3 in the Y direction, the present invention corrects the Abbe error through formula (1), so that the measurement result is converted from a relative change to an absolute change. Compared with the traditional lever meter, the measurement accuracy of the present invention is higher, and it can be integrated into intelligent manufacturing. Compared with the existing digital lever meter, the cost is lower. Secondly, the linear displacement sensor provided by the present invention has lower requirements on posture placement when in use, which further reduces the learning cost for beginners and helps to improve the reliability of the measurement results and work efficiency.

[0103] Finally, the method of the present application is only a preferred implementation scheme and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0104] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A high-precision linear displacement sensor, characterized in that: It comprises a rotating shaft rotatably arranged in a shell, a measuring needle is fixed to one end of the rotating shaft, an angle encoder is connected to the other end of the rotating shaft, and a posture sensor is also arranged on the rotating shaft between the angle encoder and the measuring needle.

2. The high-precision linear displacement sensor according to claim 1, characterized in that: The measuring needle is threadedly connected to the rotating shaft.

3. The high-precision linear displacement sensor according to claim 1, characterized in that: The position and posture sensor is fixed on the rotating shaft by bonding.

4. The high-precision linear displacement sensor according to claim 1, characterized in that: It also includes a display screen and a controller, and the controller is communicatively connected with the display screen, the angle encoder and the posture sensor respectively.

5. A measurement method comprising the high-precision linear displacement sensor according to any one of claims 1 to 4, characterized in that: The steps include: S1: The stylus is attached to the workpiece to be measured. When the workpiece to be measured moves, the stylus rotation angle p°, the stylus inclination angle X° in the X direction, and the stylus inclination angle Y° in the Y direction are obtained; S2: Then calculate the height change value H of the workpiece to be measured by the following formula (1): H=L×sinP°×cosY°×sin(90-X)°+(LL×cos P°)×sinX° (1) Where L is the length of the probe.

6. The measuring method according to claim 5, characterized in that: After step S2, the following step is also included: displaying the height change value H of the workpiece to be measured on the display screen.

7. The measuring method according to claim 5, characterized in that: In step S1 , the angle p° of the probe rotation is obtained by an angle encoder.

8. The measuring method according to claim 7, characterized in that: In step S1, the inclination angle X° in the X direction and the inclination angle Y° in the Y direction of the probe are obtained by a posture sensor.

9. The measuring method according to claim 5, characterized in that: When the inclination angle of the stylus in the Y direction is 0°, the height change value H of the workpiece to be measured can also be calculated by the following formula (2):

10. The measuring method according to claim 5, characterized in that: In step S2, the specific steps of obtaining formula (1) are: S21: The stylus rotates around point A, and the stylus is connected to the reference plane at point B. The inclination angle of the stylus in the X direction is X°. When the inclination angle of the stylus in the Y direction is 0°, the stylus is connected to the plane to be measured at point E'; when the inclination angle of the stylus in the Y direction is Y°, the stylus rotates at an angle of P°, and the stylus is connected to the plane to be measured at point E; S22: Draw EC through point E, perpendicular to AB at point C, and split the projection height H of BE into the sum of the projection heights of BC and CE; S23: The projection height of CE is H 1 , H 1 Obtained by the following formula (3): H 1 =L×sinP°×cosY°×sin(90-X)° (3) S24: The projection height of BC is H 2 , H 2 Obtained by the following formula (4): H 2 =(X-L×cosP°)×sinX° (4)。

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