Wall thickness uniformity measuring device

Abstract

The invention provides a wall thickness uniformity measuring device. The wall thickness uniformity measuring device comprises a displacement platform, a test tool which is fixedly mounted relative to a displacement part of the displacement platform, a capacitive sensor and a Hall probe which are arranged on the lower surface of the test tool, a permanent magnet column arranged on the upper surface of the Hall probe, and a split type magnetic bead. The device for measuring the wall thickness uniformity belongs to semi-contact measurement, can effectively detect the wall thickness uniformity under the condition that the measurement position is limited, is especially suitable for the wall thickness uniformity of a small-aperture vacuum chamber cavity with a long and narrow internal space, and facilitates the measurement of the wall thickness uniformity of a thin sheet, especially a long thin sheet.

Description

Technical Field

[0001] The invention belongs to the field of measurement technology, and in particular relates to a wall thickness uniformity measuring device. The measuring method is particularly suitable for measuring the wall thickness uniformity of a vacuum chamber cavity with a relatively smooth inner wall. Background Art

[0002] The vacuum undulator is a key device for synchrotron radiation sources and free electron lasers. It is equipped with a small-aperture vacuum chamber. The electron beam passes through the undulator along the small-aperture vacuum chamber to generate X-rays that have extremely important applications in many fields such as physics, chemistry, and materials. It can be seen that the small-aperture vacuum chamber provides a channel for the beam, but it has the characteristics of long length, small aperture, and high requirements for the smoothness of the inner surface. In addition, whether the thickness of the vacuum chamber cavity is uniform directly affects the beam state of the electrons in the vacuum chamber cavity, thereby affecting the beam quality and ultimately causing the performance of the equipment to decline.

[0003] Figure 1 and Figure 2 Figure 1 shows a typical long vacuum chamber with a narrow aperture and a schematic diagram of the structure and cross-section. Figure 1 and Figure 2 As shown, the vacuum chamber cavity includes a vacuum chamber upper wall 101, a vacuum chamber lower wall 102, a vacuum chamber side wall 103, and an inner space 104 defined by the vacuum chamber upper wall 101, the vacuum chamber lower wall 102 and the vacuum chamber side wall 103. The vacuum chamber cavity of this example is a circle with an inner diameter of 8 mm.

[0004] For the vacuum chamber cavity, although some thickness measurement systems can be used to measure the overall thickness of the upper and lower walls of the vacuum chamber cavity, the inner diameter of the vacuum chamber cavity in its internal space is 8mm, and the length can reach more than 4m. After measuring the overall thickness of the upper and lower walls, the user is limited by the volume of the vacuum chamber space and cannot measure the uniformity of the wall thickness of the vacuum chamber cavity. Conventional measurement tools are more convenient for measuring the wall thickness at the entrance and exit of the vacuum chamber cavity, but because the internal space of the vacuum chamber cavity is long and narrow, it is difficult to measure the uniformity of the wall thickness between the entrance and the exit. Summary of the invention

[0005] The object of the present invention is to provide a wall thickness uniformity measuring device, so as to effectively detect the wall thickness uniformity when the measuring position and space are limited.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a wall thickness uniformity measuring device, including a displacement platform, a test fixture fixedly installed relative to the displacement part of the displacement platform, a capacitive sensor and a Hall probe arranged on the lower surface of the test fixture, a permanent magnet column arranged on the upper surface of the Hall probe, and a split magnetic bead arranged in a vacuum chamber.

[0007] The testing tool is arranged parallel to the surface of the first side of the sheet material to be tested, so that the capacitive sensor and the Hall probe are facing the first side of the sheet material to be tested, and the split magnetic beads are attached to the surface of the second side of the sheet material to be tested.

[0008] The capacitive sensor is used to measure the second distance from the capacitive sensor to the first side surface of the sheet material to be measured, and the split magnetic bead and the Hall probe are opposite to each other to measure the first distance from the Hall probe to the second side surface of the sheet material to be measured through the Hall probe, and the first distance and the second distance are used to obtain the wall thickness.

[0009] The wall thickness uniformity measuring device also includes a signal acquisition and processing system connected to both the capacitive sensor and the Hall probe, the signal acquisition and processing system includes a capacitive sensor controller connected to the capacitive sensor for communication, a voltage acquisition device connected to the Hall probe, and an industrial computer connected to the capacitive sensor controller and the voltage acquisition device for communication, the industrial computer is also connected to the displacement platform to obtain the current position of the displacement part of the displacement platform.

[0010] The voltage acquisition device is configured to acquire the Hall induced voltage of the Hall probe, and the capacitive sensor controller is configured to acquire and process the second distance from the capacitive sensor to the first side surface of the sheet material to be tested; the industrial computer is configured to obtain the first distance from the Hall probe to the second side surface of the sheet material to be tested based on the relationship between the multiple groups of Hall induced voltages that are pre-tested and calibrated and the corresponding Hall induced voltages and the second side surface of the sheet material, and the Hall induced voltage measured by the voltage acquisition device; the industrial computer is configured to enable the displacement platform to drive the test tooling to scan along a direction parallel to the sheet material to be tested during the test, and control the voltage acquisition device and the capacitive sensor controller to acquire synchronously, obtain the first distance corresponding to the Hall induced voltage from the voltage acquisition device and the second distance from the capacitive sensor controller, and obtain the wall thickness based on the processed first distance and second distance.

[0011] Pre-testing and calibrating the relationship between multiple sets of Hall induced voltages and the corresponding first distances from the Hall probe to the second side surface of the sheet material specifically includes: driving the test fixture to move in a direction perpendicular to the sheet material through a displacement platform to change the first distance from the Hall probe to the second side surface of the sheet material; at the same time, testing the first distance and the corresponding Hall induced voltage to obtain a relationship curve between the Hall induced voltage and the first distance based on the multiple sets of Hall induced voltages and the first distance.

[0012] The sheet material to be tested is the upper wall or lower wall of the vacuum chamber cavity of the vacuum chamber; in the process of the displacement platform driving the test tooling to scan along the direction parallel to the sheet material to be tested, the speed and direction instructions sent by the industrial computer to the displacement platform enable the displacement platform to drive the test tooling to start scanning from the entrance of the vacuum chamber and end scanning at the exit of the vacuum chamber.

[0013] The wall thickness is obtained by subtracting the first distance and the second distance collected at the same time; or, the capacitive sensor and the Hall probe are relatively stationary, and the distance between the capacitive sensor and the Hall probe is the third distance; the wall thickness is obtained according to the following formula: L=L1(L3)-L2, wherein L3 is the third distance, L1(L3) is the first distance corresponding to the current moment after moving the third distance, and L2 is the second distance at the current moment.

[0014] The test fixture is fixed on a fixture fixture of an aluminum structure by means of demagnetized stainless steel screws, and the fixture fixture is fixed on the side of the marble vertical axis of the displacement platform.

[0015] The material of the test fixture is epoxy resin board.

[0016] The wall thickness uniformity measuring device of the present invention belongs to semi-contact measurement (the split magnetic bead wire in the test device contacts the second side surface of the thin sheet, and the rest is non-contact), which can effectively detect the wall thickness uniformity when the measuring position and space are limited. It is particularly suitable for the wall thickness uniformity of a small-aperture vacuum chamber cavity with a long and narrow internal space. Secondly, it is also convenient to measure the wall thickness uniformity of a thin sheet, especially a thin sheet with a long length. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a typical long vacuum chamber with a narrow aperture; Figure 2 This is a cross-section of a typical long vacuum chamber with a narrow aperture; Figure 3 is a schematic diagram of the overall structure of a wall thickness uniformity measuring device according to an embodiment of the present invention; Figure 4 For Figure 3 A schematic diagram of the structure of a fixture and a test fixture of a wall thickness uniformity measuring device shown; Figure 5 For Figure 3 A system block diagram of a signal acquisition and processing system for a wall thickness uniformity measuring device is shown.

[0018] The accompanying drawings are marked as follows: 101-upper wall of the vacuum chamber, 1-displacement platform, 2-tooling fixture, 3-testing tooling, 4-capacitive sensor, 5-Hall probe, 6-permanent magnet column, 7-split magnetic bead, 8-capacitive sensor controller, 9-voltage acquisition equipment, 10-industrial computer, L1-first distance; L2-second distance, L3-third distance, L-wall thickness. DETAILED DESCRIPTION

[0019] In order to enable people skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention.

[0020] like Figure 3-Figure 5 The wall thickness uniformity measuring device according to one embodiment of the present invention is shown, which is used to measure the wall thickness uniformity of a sheet material to be measured, especially the wall thickness uniformity of a vacuum chamber cavity. The wall thickness uniformity measuring device comprises a high-precision displacement platform 1, a test fixture 3 fixedly installed relative to the displacement part of the displacement platform 1, a capacitive sensor 4 and a Hall probe 5 arranged on the lower surface of the test fixture 3, a permanent magnet column 6 arranged on the upper surface of the Hall probe 5, and a split magnetic bead 7.

[0021] During the test, the test fixture 3 is arranged parallel to the surface of the first side of the sheet material to be tested, so that the capacitive sensor 4 and the Hall probe 5 are facing the first side of the sheet material to be tested, and the split magnetic bead 7 is attached to the surface of the second side of the sheet material to be tested. Therefore, the capacitive sensor 4 is used to measure the second distance L2 from the capacitive sensor 4 to the first side surface of the sheet material to be tested, and due to the presence of the permanent magnet column 6, the split magnetic bead 7 and the Hall probe 5 are facing each other to measure the first distance L1 from the Hall probe 5 to the second side surface of the sheet material to be tested (i.e., the center of the magnetic bead) through the Hall probe 5. The first distance L1 and the second distance L2 are used to obtain the wall thickness, thereby achieving the measurement of the wall thickness and the uniformity of the wall thickness.

[0022] In this embodiment, the sheet material to be tested is as follows Figure 1 The upper wall 101 of the vacuum chamber cavity of the vacuum chamber shown. Therefore, the split magnetic bead 7 is arranged inside the vacuum chamber cavity, and the test fixture 3 is arranged outside the vacuum chamber cavity and placed parallel to the upper surface of the vacuum chamber cavity. The physical quantity measured by the capacitive sensor 4 is the distance from the capacitive sensor 4 to the outer wall of the vacuum chamber, and the reading unit is mm. In other embodiments, when the sheet material to be tested is the lower wall 102 of the vacuum chamber cavity of the vacuum chamber cavity, the vacuum chamber cavity is flipped over so that the test fixture 3 is placed parallel to the original lower surface of the vacuum chamber cavity.

[0023] The test fixture 3 is fixed to the fixture fixture 2 of the aluminum structure by demagnetized stainless steel screws, and the fixture fixture 2 is fixed to the side of the marble vertical axis of the displacement platform 1 to achieve relative fixation of the displacement platform 1 and the test fixture 3. The XYZ three-axis of the marble can move relative to the ground, thereby driving the displacement platform 1 and the test fixture 3 to move synchronously.

[0024] like Figure 2 and 3 As shown, the capacitive sensor 4 and the Hall probe 5 are both planar measuring devices, so that the test fixture 3 can be placed parallel to the upper surface of the vacuum chamber cavity. The capacitive sensor 4 and the Hall probe 5 are closely attached to the lower surface of the test fixture 3. During measurement, the capacitive sensor 4 and the Hall probe 5 are basically parallel to a horizontal plane (i.e., the XOZ plane) of the displacement platform 1. The capacitive sensor 4 and the Hall probe 5 are relatively stationary, and are basically parallel to the X-axis direction and the Z-axis direction, and thus parallel to the outer surface of the upper wall of the vacuum chamber cavity. The XOZ plane of the displacement platform 1 is parallel to the outer surface of the upper wall of the vacuum chamber cavity by using a laser tracker to align the entire vacuum chamber cavity with the fixed base (6.5m base marble) of the displacement platform 1 as a reference.

[0025] The capacitive sensor 4 and the Hall probe 5 are relatively still, and the distance between the capacitive sensor 4 and the Hall probe 5 is a third distance L3. The third distance L3 and the diameter of the split magnetic bead 7 can be obtained through theoretical simulation calculation.

[0026] like Figure 3 and Figure 5 As shown, the wall thickness uniformity measuring device also includes a signal acquisition processing system connected to both the capacitive sensor 4 and the Hall probe 5, and the signal acquisition processing system includes a capacitive sensor controller 8 connected to the capacitive sensor 4, a voltage acquisition device 9 connected to the Hall probe 5, and an industrial computer 10 connected to the capacitive sensor controller 8 and the voltage acquisition device 9. The capacitive sensor controller 8 and the voltage acquisition device 9 are connected to the industrial computer 10 via Modbus TCP and TCP / IP communication protocols, respectively. The industrial computer 10 is also connected to the position module of the displacement platform 1 to obtain the current position of the displacement part of the displacement platform 1.

[0027] The voltage acquisition device 9 is configured to collect the Hall induced voltage of the Hall probe 5, wherein the Hall probe 5 can detect changes in the Hall induced voltage, and the Hall induced voltage is closely correlated with the distance from the permanent magnet column to the magnetic bead. Therefore, based on this theory, the relationship between the Hall induced voltage U and the first distance L1 from the Hall probe 5 to the second side surface of the sheet material to be measured is calibrated.

[0028] Accordingly, the industrial computer 10 is configured to obtain the first distance L1 from the second side surface of the sheet material to be measured by the Hall probe 5 according to the relationship between the pre-tested and calibrated multiple sets of Hall induced voltages U and the corresponding Hall probe 5 and the first distance L1 from the second side surface of the sheet material and the Hall induced voltage measured by the voltage acquisition device 9. In the following embodiment, the relationship between the Hall induced voltage U and the first distance L1 is first calibrated, because the simulation theory calculates that the voltage U change caused by the change in L1 is much greater than the change in the X and Z directions.

[0029] In this embodiment, the relationship between multiple groups of Hall induced voltages U and the corresponding first distance L1 from the Hall probe 5 to the second side surface of the sheet material is pre-tested and calibrated, specifically including: driving the test fixture 3 to move in a direction perpendicular to the sheet material (i.e., the Y direction) by the displacement platform 1 to change the first distance L1 from the Hall probe to the second side surface of the sheet material, with a repeatability accuracy better than ±1um; at the same time, testing the first distance L1 and the corresponding Hall induced voltage U to obtain a relationship curve L1 (U) between the Hall induced voltage U and the first distance L1 based on the multiple groups of Hall induced voltages U and the first distance L1.

[0030] The capacitive sensor controller 8 is configured to collect and process a second distance L2 from the capacitive sensor to the first side surface of the sheet material to be measured, with the reading unit being mm.

[0031] The industrial computer 10 is configured to enable the displacement platform 1 to drive the test fixture 3 to scan in a direction parallel to the sheet material to be tested (e.g., scanning in the Z direction of the vacuum chamber) during testing, and control the voltage acquisition device 9 and the capacitive sensor controller 8 to synchronously acquire data, thereby obtaining a first distance corresponding to the Hall induced voltage from the voltage acquisition device 9 and a second distance L2 from the capacitive sensor to the first side surface of the sheet material to be tested from the capacitive sensor controller 8, and obtaining the wall thickness L based on the processed first distance L1 and second distance L2.

[0032] In one embodiment, the wall thickness L is obtained by subtracting the first distance L1 and the second distance L2 collected at the same time.

[0033] In this embodiment, the wall thickness L is obtained according to the following formula: L=L1(L3)-L2, Among them, L3 is the third distance, L1(L3) is the first distance corresponding to the current moment after moving the third distance, and L2 is the second distance at the current moment.

[0034] In this embodiment, the acquisition trigger frequency of the capacitive sensor 4 and the Hall probe 5 is triggered at equal distances according to the position, such as one acquisition point every 0.2 mm, and is transmitted to the industrial computer 10 through the capacitive sensor controller 8 and the voltage acquisition device 9. In this embodiment, the effective measurement range of the second distance L2 measured by the capacitive sensor 4 is 0.5 mm, the resolution is 0.5 μm, and the repeatability is ±0.5 μm.

[0035] In this embodiment, the industrial computer 10 is connected to the displacement platform 1, and the two communicate via the TCP / IP protocol (Transmission Control Protocol / Internet Protocol). The industrial computer 10 is configured to send speed and direction instructions to the displacement platform 1 through operations on its operation interface, so that the displacement platform 1 drives the test fixture 3 to move in the directions of three degrees of freedom (i.e., X / Y / Z directions).

[0036] As described above, the displacement platform 1 drives the test fixture 3, specifically including the displacement platform 1 driving the test fixture 3 to move in the Y direction to change the first distance L1 while testing the Hall induced voltage U, calibrating the relationship between the first distance L1 and the Hall induced voltage U, thereby indirectly obtaining L1(U); and the displacement platform 1 drives the test fixture 3 to scan in the Z direction, and controls the voltage acquisition device 9 and the capacitive sensor controller 8 to collect synchronously. During the measurement process, the capacitive sensor 4, the Hall probe 5, and the magnetic column 6 keep their relative positions unchanged. Since the inner surface of the vacuum chamber is smooth, the magnetic beads follow the magnetic column 6 and move slightly behind.

[0037] In this embodiment, when the displacement platform 1 drives the test fixture 3 to scan in a direction parallel to the sheet material to be tested, the speed and direction instructions sent by the industrial computer 10 to the displacement platform 1 enable the displacement platform 1 to drive the test fixture 3 to start scanning from the entrance of the vacuum chamber and end scanning at the exit of the vacuum chamber. Thus, the entire vacuum chamber is scanned, and the first distance L1 and the second distance L2 at different positions can be measured respectively.

[0038] In addition, the scanning start instruction sent by the industrial computer 10 to the displacement platform 1 causes the displacement platform 1 to drive the test fixture 3 to move along the X-axis direction, the Y-axis direction and the Z-axis direction to a position above the sheet material and within a suitable range of the second distance L2, as the starting scanning position. The speed and direction instructions sent by the industrial computer 10 to the motion platform 1 cause the motion direction of the motion platform 1 to be parallel to the surface of the sheet material during scanning, thereby facilitating measurement.

[0039] Specifically, the scanning start instruction sent by the industrial computer 10 to the displacement platform 1 causes the displacement platform 1 to drive the test fixture 3 to move in the X direction for testing, and finds the X coordinate of the displacement platform 1 corresponding to when the Hall induced voltage U reaches the maximum value Umax, which is used as the X coordinate X0 of the starting scanning position; the displacement platform 1 adjusts the value of the second distance L2 within the range of the capacitive sensor 4, and uses the Y coordinate of the displacement platform 1 at this time as the Y coordinate Y0 of the starting scanning position. During scanning, X0 and Y0 are kept unchanged, and the Z coordinate of the displacement platform 1 is scanned from the entrance position Zi of the vacuum chamber to the exit position Zo.

[0040] In this embodiment, the material of the test fixture 3 is an epoxy resin plate, because the epoxy resin plate material will not be magnetized. The test fixture 3 has different versions, and the shape of the test fixture 3 is customized. To ensure its invariance, the rigidity of the aluminum structure fixing part to fix it must be ensured to be good.

[0041] The wall thickness uniformity measuring device of the present invention belongs to semi-contact measurement (the split magnetic bead wire in the test device contacts the second side surface of the thin sheet, and the rest is non-contact), which can effectively detect the wall thickness uniformity when the measurement position is limited. It is particularly suitable for the wall thickness uniformity of a small-aperture vacuum chamber cavity with a long and narrow internal space. Secondly, it is also convenient to measure the wall thickness uniformity of a thin sheet, especially a thin sheet with a long length.

[0042] Although the above describes specific embodiments of the present invention, it does not limit the scope of the present invention, but is merely an example. Other changes may be made to these embodiments without departing from the essence of the present invention. Therefore, the scope of protection of the present invention is limited by the appended claims.

Claims

1. A wall thickness uniformity measuring device, characterized in that: The invention comprises a displacement platform, a test fixture fixedly installed relative to the displacement part of the displacement platform, a capacitive sensor and a Hall probe arranged on the lower surface of the test fixture, a permanent magnet column arranged on the upper surface of the Hall probe, and a split magnetic bead.

2. The wall thickness uniformity measuring device according to claim 1, characterized in that: The testing tool is arranged parallel to the surface of the first side of the sheet material to be tested, so that the capacitive sensor and the Hall probe are facing the first side of the sheet material to be tested, and the split magnetic beads are attached to the surface of the second side of the sheet material to be tested.

3. The wall thickness uniformity measuring device according to claim 2, characterized in that: The capacitive sensor is used to measure the second distance from the capacitive sensor to the first side surface of the sheet material to be measured, and the split magnetic bead and the Hall probe are opposite to each other to measure the first distance from the Hall probe to the second side surface of the sheet material to be measured through the Hall probe, and the first distance and the second distance are used to obtain the wall thickness.

4. The wall thickness uniformity measuring device according to claim 1, characterized in that: It also includes a signal acquisition and processing system connected to both the capacitive sensor and the Hall probe, the signal acquisition and processing system includes a capacitive sensor controller communicatively connected to the capacitive sensor, a voltage acquisition device connected to the Hall probe, and an industrial computer communicatively connected to the capacitive sensor controller and the voltage acquisition device, the industrial computer is also connected to the displacement platform to obtain the current position of the displacement part of the displacement platform.

5. The wall thickness uniformity measuring device according to claim 4, characterized in that: The voltage acquisition device is configured to acquire the Hall induced voltage of the Hall probe, and the capacitive sensor controller is configured to acquire and process the second distance from the capacitive sensor to the first side surface of the sheet material to be measured; The industrial computer is configured to obtain the first distance from the Hall probe to the second side surface of the sheet material to be measured based on the relationship between the multiple sets of Hall induced voltages and the corresponding first distances from the Hall probe to the second side surface of the sheet material that are pre-tested and calibrated, and the Hall induced voltage measured by the voltage acquisition device; The industrial computer is configured to enable the displacement platform to drive the test fixture to scan in a direction parallel to the sheet material to be tested during testing, and to control the voltage acquisition device and the capacitive sensor controller to synchronously acquire data, thereby obtaining a first distance corresponding to the Hall induced voltage from the voltage acquisition device and a second distance from the capacitive sensor controller, and obtaining the wall thickness based on the processed first distance and second distance.

6. The wall thickness uniformity measuring device according to claim 5, characterized in that: Pre-testing and calibrating the relationship between multiple sets of Hall induced voltages and the corresponding first distances from the Hall probe to the second side surface of the sheet material specifically includes: driving the test fixture to move in a direction perpendicular to the sheet material through a displacement platform to change the first distance from the Hall probe to the second side surface of the sheet material; at the same time, testing the first distance and the corresponding Hall induced voltage to obtain a relationship curve between the Hall induced voltage and the first distance based on the multiple sets of Hall induced voltages and the first distance.

7. The wall thickness uniformity measuring device according to claim 5, characterized in that: The sheet material to be tested is the upper wall or lower wall of the vacuum chamber cavity; in the process of the displacement platform driving the test fixture to scan along the direction parallel to the sheet material to be tested, the speed and direction instructions sent by the industrial computer to the displacement platform enable the displacement platform to drive the test fixture to start scanning from the entrance of the vacuum chamber and end scanning at the exit of the vacuum chamber.

8. The wall thickness uniformity measuring device according to claim 5, characterized in that: The wall thickness is obtained by subtracting the first distance and the second distance collected at the same time; Alternatively, the capacitive sensor and the Hall probe are relatively stationary, and the distance between the capacitive sensor and the Hall probe is a third distance L3; the wall thickness is obtained according to the following formula: L=L1(L3)-L2, Among them, L3 is the third distance, L1(L3) is the first distance corresponding to the current moment after moving the third distance, and L2 is the second distance at the current moment.

9. The wall thickness uniformity measuring device according to claim 1, characterized in that: The test fixture is fixed on a fixture fixture of an aluminum structure by means of demagnetized stainless steel screws, and the fixture fixture is fixed on the side of the marble vertical axis of the displacement platform.

10. The wall thickness uniformity measuring device according to claim 1, characterized in that: The material of the test fixture is epoxy resin board.

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