Non-contact polishing constant force control and gap adjustment device and method

Abstract

The application discloses a kind of non-contact polishing constant force control and gap adjusting device and method, including workpiece table, pressure sensor, displacement sensor, base, micro-displacement platform, processing head and workpiece.By composite sensing measurement of pressure sensor and displacement sensor, processing head can be contacted to sense workpiece in static state to accurately and quickly regulate and control processing gap;When processing head rotates and processes, pressure sensor and displacement sensor can composite sensing polishing pressure and the micro-displacement generated by the deformation of sensor due to pressure, compared with initial value, then realize constant force control by micro-displacement platform movement.The application solves the problem that processing gap cannot be accurately and quickly regulated and controlled, and polishing pressure cannot be monitored and adjusted in real time due to gap change during processing.

Description

Technical Field

[0001] This invention relates to the field of advanced optical manufacturing, and in particular to a device and method for constant force control and gap adjustment in non-contact polishing. Background Technology

[0002] Grinding and polishing is one of the main ways to obtain ultra-smooth surfaces. Traditional contact polishing has high polishing efficiency but poor polishing quality. Non-contact polishing avoids direct contact between the abrasive and the workpiece, reduces damage to the processed surface, and can help achieve ultra-smooth surface processing.

[0003] A typical example of non-contact polishing is elastic emission machining (EEM), an ultra-precision machining method proposed by Professor Yuzo Mori of Osaka University in the 1970s. Unlike traditional polishing using abrasive pads, EEM is a non-contact machining process. There is a micron-level gap between the machining head and the machining element. First, the chemical bonds of the atoms on the surface of the optical element are weakened through chemical action. Then, the rotation of the machining head drives the polishing fluid to generate fluid shear force. Under the action of shear force, the chemical bonds of the surface atoms break, thereby achieving the removal of surface material at the atomic level.

[0004] In her article "Research Progress in Elastic Emission Optical Manufacturing Technology," Li Jiahui summarized the development history of elastic emission processing devices, classifying them into two categories: gap-adaptive EEM processing devices and gap-non-adaptive EEM processing devices. Gap-non-adaptive EEM devices suffer from a decrease in material removal rate over processing time, while gap-adaptive EEM devices cannot achieve precise gap control due to low gap control accuracy and high latency.

[0005] Currently, gap adjustment is divided into static and dynamic adjustments. When the machining head is stationary, gap adjustment is mainly achieved using feeler gauges, force sensors on the machine tool, or dial indicators (CN210753473U, CN114563981A). Using feeler gauges is cumbersome and relies on the operator's feel, which is inaccurate and can easily scratch the workpiece surface during measurement. Force sensors or dial indicators on the machine tool require establishing a dimensional chain, and multiple indirect measurements can increase errors. During machining, i.e., in a dynamic state, the polishing fluid is opaque or turbid, making it difficult to directly measure and adjust the polishing gap in real time. Measuring polishing force is relatively easier than measuring gap, therefore, a device is urgently needed to accurately control the polishing gap in both static and dynamic states.

[0006] To address the two problems mentioned above, this invention proposes a non-contact polishing constant force control and gap adjustment device and method. This device can quickly adjust the polishing gap when the processing head is static, measure the correspondence between the polishing gap and the polishing pressure when the head is dynamic, and adjust the polishing pressure in real time to keep the polishing pressure within a constant range. Summary of the Invention

[0007] This invention proposes a non-contact polishing constant force control and gap adjustment device and method to solve the problems in the prior art where the processing gap cannot be quickly and accurately controlled, and the polishing pressure cannot be monitored and adjusted in real time due to changes in the polishing gap during the processing.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A non-contact polishing constant force control and gap adjustment device includes a workpiece stage, a pressure sensor fixedly connected to the lower part of the workpiece stage, a base fixedly connected to the other end of the pressure sensor, a displacement sensor fixedly connected to the upper part of the base, and a micro-displacement platform fixedly connected to the lower part of the base.

[0010] Furthermore, a workpiece is fixedly connected to the workpiece table; a processing head is provided on the workpiece; during the processing, there is a gap S between the processing head and the workpiece, and the processing head and the workpiece can come into contact during the gap adjustment process.

[0011] This invention also provides a method for constant force control and gap adjustment in non-contact polishing. The method is implemented using the aforementioned non-contact polishing constant force control and gap adjustment device, and includes the following steps:

[0012] Step a: Zero the pressure sensor and displacement sensor so that their readings are 0;

[0013] Step b: Slowly feed the machining head towards the workpiece. Stop feeding when the pressure sensor and displacement sensor readings are not 0, indicating that the machining head is in contact with the workpiece. Slowly feed the machining head away from the workpiece until the pressure sensor and displacement sensor readings are exactly 0, at which point the gap between the machining head and the workpiece is 0. Based on this, feed the machining head away from the workpiece by a stroke S, at which point the gap between the machining head and the workpiece is S.

[0014] Step c: Adjust the machining head to the machining area, and using the method described in step b, adjust the gap between the machining head and the workpiece to the specified S. Start the machining program and record the initial pressure value and initial displacement value of the pressure sensor and displacement sensor as F1 and δ1, respectively.

[0015] Step d: During the processing, the pressure sensor and displacement sensor measure in real time to obtain the real-time pressure value and the real-time displacement value F2 and δ2, calculate the pressure difference value ΔF=F2-F1 and the small displacement difference value Δδ=δ2-δ1, and feed ΔF and Δδ back to the micro-displacement platform;

[0016] Step e: The micro-displacement platform performs micro-displacement motion based on ΔF and Δδ, so that ΔF and Δδ approach 0;

[0017] Step f: Repeat steps d-e until the processing is complete.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. This invention enhances the accuracy of the measurement process by using a pressure sensor and a displacement sensor for combined sensing.

[0020] 2. When the machining head is stationary, it can accurately and quickly adjust the machining gap by contact sensing of the workpiece. When the machining head rotates, the pressure sensor and displacement sensor can jointly sense the polishing pressure and the micro-displacement caused by the deformation of the sensor due to the pressure. The values ​​are compared with the initial values, and closed-loop control is achieved through the micro-displacement platform. This solves the problem that the polishing pressure cannot be monitored and adjusted in real time due to gap changes during the machining process, and enables controllable material removal.

[0021] 3. The device of the present invention has a simple structure and strong stability, and can be applied to non-contact polishing and ultra-precision machining, including but not limited to elastic emission processing. Attached Figure Description

[0022] Figure 1 This is the front view of the present invention;

[0023] Figure 2 This is a three-dimensional schematic diagram of the overall structure of the present invention;

[0024] In the diagram: 1-Workpiece stage; 2-Pressure sensor; 3-Displacement sensor; 4-Base; 5-Micro-displacement platform; 6-Processing head; 7-Processed part. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] Please see Figure 1 and Figure 2The present invention provides an embodiment of a non-contact polishing constant force control and gap adjustment device, including a workpiece stage 1, a pressure sensor 2 fixedly connected to the bottom of the workpiece stage 1; a base 4 fixedly connected to the other end of the pressure sensor 2; a displacement sensor 3 fixedly connected to the top of the base 4; and a micro-displacement platform 5 fixedly connected to the bottom of the base 4.

[0027] Preferably, in this embodiment, the displacement sensor 3 is a laser displacement sensor. After the laser is emitted towards the target workpiece stage 1, the round-trip time of the laser is measured, and then multiplied by the speed of light to obtain the round-trip distance, thereby obtaining the size of the gap, and thus realizing non-contact measurement.

[0028] A workpiece 7 is fixedly connected to the workpiece stage 1; a workpiece 7 has a workpiece head 6; during the processing, there is a gap of 1-100 micrometers between the workpiece head 6 and the workpiece 7, and the workpiece head 6 and the workpiece 7 can come into contact during the gap adjustment process.

[0029] This invention provides a method for constant force control and gap adjustment in non-contact polishing. In a specific embodiment, the constant force control and gap adjustment steps are as follows:

[0030] Step a: Zero out pressure sensor 2 and displacement sensor 3 so that their readings are 0;

[0031] Step b: Slowly feed the machining head 6 towards the workpiece 7, that is, slowly feed the machining head 6 towards the normal direction of the surface of the workpiece 7. Stop feeding when the readings of the pressure sensor 2 and the displacement sensor 3 are not 0, and determine that the machining head 6 is in contact with the workpiece 7 at this time; Slowly feed the machining head 6 away from the workpiece 7 until the readings of the pressure sensor 2 and the displacement sensor 3 are exactly 0, at which point the gap between the machining head 6 and the workpiece 7 is 0; Based on this, feed the machining head 6 away from the workpiece 7 by a stroke S, at which point the gap between the machining head 6 and the workpiece 7 is S.

[0032] Step c: Adjust the machining head 6 to the machining area, and use the method described in step b to adjust the gap S between the machining head 6 and the workpiece 7 to 30 micrometers; start the machining program, and record the initial pressure value and displacement value of the pressure sensor 2 and the displacement sensor 3 as F1 = 10N and δ1 = 0.0050mm;

[0033] Step d: During the processing, the pressure sensor 2 and displacement sensor 3 measure the pressure and displacement values ​​in real time as F2 = 15N and δ2 = 0.0025mm, respectively, and calculate the pressure difference ΔF = F2 - F1 = 5N and the small displacement difference Δδ = δ2 - δ1 = -0.0025mm, respectively, and feed back ΔF = 5N and Δδ = -0.0025mm to the micro-displacement platform 5;

[0034] Step e: The micro-displacement platform 5 moves the machining head 6 away from the workpiece 7 in a micro-displacement direction according to ΔF and Δδ. This micro-displacement movement is also along the normal direction of the surface of the workpiece 7, so that ΔF and Δδ approach 0.

[0035] Step f: Repeat steps d-e until the processing is complete.

[0036] The constant force control and gap adjustment method in non-contact polishing provided by the present invention can be used in non-contact polishing processes with high requirements for polishing gap.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for constant force control and gap adjustment in non-contact polishing, the method being implemented by a device for constant force control and gap adjustment in non-contact polishing, the device comprising a workpiece stage (1), a pressure sensor (2) fixedly connected below the workpiece stage (1); a base (4) fixedly connected to the other end of the pressure sensor (2); a displacement sensor (3) fixedly connected above the base (4); a micro-displacement platform (5) fixedly connected below the base (4); a workpiece (7) fixedly connected to the workpiece stage (1); a processing head (6) provided on the workpiece (7); during processing, the processing head (6) and the workpiece (7) have a gap S, and during gap adjustment, the processing head (6) and the workpiece (7) can come into contact; characterized in that, The method includes the following steps: Step a: Zero the pressure sensor (2) and displacement sensor (3) so that their readings are 0; Step b: Slowly feed the machining head (6) towards the workpiece (7). Stop feeding when the readings of the pressure sensor (2) and displacement sensor (3) are not 0. At this time, it is determined that the machining head (6) is in contact with the workpiece (7). Slowly feed the machining head (6) away from the workpiece (7) until the readings of the pressure sensor (2) and displacement sensor (3) are exactly 0. At this time, the gap between the machining head (6) and the workpiece (7) is 0. On this basis, let the machining head (6) feed a stroke S away from the workpiece (7). At this time, the gap between the machining head (6) and the workpiece (7) is S. Step c: Adjust the machining head (6) to the machining area. Using the method described in step b, adjust the gap between the machining head (6) and the workpiece (7) to the specified S. Start the machining program and record the initial pressure value and initial displacement value of the pressure sensor (2) and displacement sensor (3). and ; Step d: During the processing, the pressure sensor (2) and displacement sensor (3) measure the real-time pressure and displacement values ​​in real time. and Calculate the pressure difference value and small displacement difference and ΔF and Feedback is sent to the micro-displacement platform (5); Step e: Micro-displacement platform (5) based on ΔF and Δ Performing micro-displacement motion, so that... and Approaching 0; Step f: Repeat steps d-e until the processing is complete.

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