Pressure full-closed-loop servo control device and pressure control method thereof

Abstract

The invention discloses a pressure full-closed-loop servo control device and a pressure control method thereof.The pressure control method comprises the steps that a touch screen industrial computer sends a driving signal to a servo driver, the servo driver controls a servo motor to drive a ball screw to rotate, the ball screw drives a lead screw nut and a driving head to move in the vertical direction, and the lead screw nut drives the driving head to move in the vertical direction; the driving head is connected with the floating head through the upper and lower bearing pressure springs, and the floating head is connected with the upper disc. A displacement sensor is installed between the driving head and the floating head and used for measuring the relative compression displacement of the driving head to the compression spring and feeding back a measured value to the touch screen industrial computer at the same time, a full-closed-loop control system is formed, and the displacement action that the driving head releases or compresses the compression spring is accurately controlled. According to the pressure control device and the pressure control method, the stability and the accuracy of the loading pressure in the process of grinding / polishing the silicon wafer or the silicon carbide wafer are effectively improved in combination with the comprehensive application of the Powerlink real-time field bus technology.

Description

Technical Field

[0001] The present application relates to the technical field of pressure precision control, and in particular to a pressure full-closed-loop servo control device and a pressure control method thereof. Background Art

[0002] In recent years, with the increasing competition at home and abroad in the semiconductor industry, the requirements for the surface quality and yield rate of silicon wafers, silicon carbide wafers and other polished workpieces have become increasingly higher. Among the problems that need to be overcome, there are still many challenges in the machinability of some thin, brittle, hard, fragile and large-sized precious sheet workpieces, such as the need to provide highly stable and ultra-precise upper and lower grinding / polishing discs, the need for grinding or polishing liquids that match the process technology, and the need to provide highly stable and precisely controllable upper disc pressure. Summary of the invention

[0003] Against the above background, the embodiment of the present application provides a full-closed-loop pressure servo control device and a control method thereof, which realizes full-closed-loop servo control of upper plate pressure through the comprehensive application of touch screen industrial computers, servo drivers, servo motors, ball screws, drive heads, rebound displacement sensors, floating heads, and Powerlink Ethernet real-time field bus technology, aiming to provide high-stability and high-precision upper plate pressure to meet the special requirements of advanced grinding and polishing processes in the semiconductor industry.

[0004] In order to achieve the above technical objectives, the technical solutions adopted in the embodiments of the present application are as follows: On the one hand, the embodiment of the present application provides a pressure full-closed-loop servo control device, which includes: a bus controller and an IO module, a lower limit travel switch, a lower limit travel block, an upper plate, a floating head connecting rod (the lower end of which is connected to a ball bearing), a rebound displacement sensor, a floating head (including upper and lower bearing compression springs), a driving head, an anti-rotation guide mechanism, a fixed crossbeam, a screw nut, a ball screw, a servo motor, a deceleration mechanism, an upper limit travel switch, a top position proximity sensor, a top position sensing boss, a deceleration proximity sensor, a deceleration sensing boss, a servo driver, a touch screen industrial computer, etc.;

[0005] The touch screen industrial computer, bus controller, IO module and servo drive are connected by Powerlink cable;

[0006] Based on the pre-written program, the touch screen industrial computer sends the drive signal to the servo drive through the bus controller and IO module;

[0007] The servo drive and servo motor are connected by two wires, power cable and encoder cable, to realize the control operation of the current loop, speed loop and position loop of the servo motor;

[0008] The servo motor drives the ball screw to rotate through the reduction mechanism;

[0009] The ball screw drives the screw nut to convert the rotational torque into a driving force in the vertical direction;

[0010] The lead screw nut is connected to the upper frame of the driving head, and the lower frame of the driving head is connected to the upper and lower compression springs of the floating head;

[0011] Both the driving head and the floating head are frame-type structures;

[0012] The floating head fits with the upper and lower end surfaces of the upper and lower bearing compression springs through the inner sides of its upper and lower frames. The upper and lower bearing compression springs are located on the lower end frame of the driving head, so that the floating head can bear load in both directions, expand the pressurization range, and maintain a continuous action of stable pressurization when the load direction is switched;

[0013] The floating head is connected to the upper plate through a floating head connecting rod and a ball bearing;

[0014] A rebound displacement sensor is installed between the floating head and the driving head. The rebound displacement sensor is fixed in the connecting rod of the floating head, and its telescopic probe elastically presses against the lower end surface of the driving head.

[0015] The frames on both sides of the driving head are installed in a vertically upward sliding manner with the anti-rotation guide mechanism. Under the combined action of the lead screw nut and the anti-rotation guide mechanism, the driving head can realize free movement in the vertical direction.

[0016] Generally speaking, the movement of the drive head in the vertical direction can be divided into four stages: the stage of automatic reset to the top position after power-on; the stage of returning from the top position to the mechanical origin; the stage of moving from the mechanical origin to the maximum pressure point and then returning to the mechanical origin, that is, the stage of full closed-loop servo control of pressure; and the stage of returning from the mechanical origin to the top position after the cycle ends.

[0017] The touch screen industrial computer automatically controls the drive head to move to the top position in the initialization state. When the top position sensing boss senses the top position proximity sensor, the drive head and the upper plate stop at the top position synchronously to facilitate cleaning, maintenance of the equipment working area and loading and unloading of the polished workpieces.

[0018] Furthermore, the driving head returns to the mechanical origin from the top position, and at this point the upper plate just begins to contact the workpiece being ground and polished, and the pressure applied by the upper plate to the workpiece being ground and polished can be regarded as zero;

[0019] Furthermore, the system enters the full-closed-loop servo control mode of pressure, and the drive head moves from the mechanical origin to the maximum pressure point according to the steps set by the program, and then moves back to the mechanical origin after reaching the maximum pressure point. At the same time, a relative displacement begins to occur between the drive head and the floating head, and the relative displacement is equal to the relative deformation displacement of the upper and lower compression springs of the floating head, and is also equal to the relative expansion displacement of the elastic expansion head of the displacement sensor; at the same time, the upper plate begins to generate positive pressure or reverse pressure reduction pressure to the workpiece being polished, and the pressure value is in a proportional linear relationship with the relative displacement of the drive head relative to the floating head;

[0020] In the pressure full closed-loop servo control mode, the touch screen industrial computer sends the drive signal of the upper plate pressure set value to the servo driver;

[0021] Based on the driving signal of the upper plate pressure given value, the servo driver controls the servo motor to drive the ball screw to rotate accurately, and the ball screw controls the driving head to move up and down accurately, while accurately controlling the displacement caused by the deformation of the upper and lower compression springs of the floating head;

[0022] At the same time, the rebound displacement sensor detects the actual displacement of the drive head when the upper and lower bearing compression springs are released;

[0023] Corresponding to the actual displacement detected, the rebound displacement sensor outputs a standard analog electrical signal and feeds it back to the touch screen industrial computer;

[0024] Based on the proportional linear correspondence between the standard analog value of the feedback voltage or current and the applied pressure value, the touch screen industrial computer detects the actual pressure value applied by the upper plate on the workpiece being polished;

[0025] By comparing and judging the actual pressure value fed back and the given value, the touch screen industrial computer generates a drive signal and sends it to the servo driver for deviation correction, accurately controlling the displacement action of the drive head to release the deformation of the upper and lower compression springs, so that the actual pressure value is close to the given pressure value in real time, dynamically, accurately and stably;

[0026] When the drive head returns to the mechanical origin from the maximum pressure point according to the program steps, the pressure full closed-loop servo control cycle ends, and the drive head returns from the mechanical far point to the top position and stops;

[0027] On the other hand, the embodiment of the present application also proposes a pressure full closed-loop servo control method, which is applied to the above-mentioned pressure full closed-loop servo control device. The pressure full closed-loop servo control method includes:

[0028] Programming is done on a touch screen industrial computer to determine the displacement and speed of the drive head, and to determine the given pressure value and corresponding holding time of the upper plate applied to the workpiece to be polished in multiple stages;

[0029] When the equipment is turned on, the touch screen industrial computer sends position instructions to the servo driver in the initialization state, controls the servo motor to drive the upper plate to move quickly to the set top position and then stop. The upper plate is in a raised state to facilitate cleaning and maintenance of the equipment processing area, and to load the workpiece to be ground and polished and its planetary gear.

[0030] After the workpiece is ready to be loaded, press the work start button, and the touch screen industrial computer will issue a work start command to control the servo motor to drive the upper plate to move quickly and slowly towards the lower plate;

[0031] The upper plate and the drive head move synchronously to the mechanical origin position and then stop automatically; at this time, the upper plate just touches the workpiece being ground and polished, and the actual pressure value on the workpiece being ground and polished is close to zero;

[0032] In the automatic cycle operation mode, press the cycle start button to trigger the touch screen industrial computer-servo drive-servo motor-ball screw-rebound displacement sensor to enter the upper plate pressure full closed loop servo control mode;

[0033] In the pressure full closed-loop servo control mode, the touch screen industrial computer sends the drive signal of the upper plate pressure set value to the servo driver;

[0034] Based on the driving signal of the given value of the upper plate pressure, the servo driver controls the servo motor to drive the ball screw to rotate accurately, and the ball screw controls the driving head to move up and down accurately, and accurately controls the displacement caused by the deformation of the upper and lower compression springs of the floating head. At the same time, the rebound displacement sensor detects the actual displacement of the driving head releasing the deformation of the upper and lower compression springs;

[0035] Corresponding to the actual displacement detected, the rebound displacement sensor outputs a standard analog electrical signal and feeds it back to the touch screen industrial computer;

[0036] Based on the proportional linear correspondence between the standard analog value of the feedback voltage or current and the applied pressure value, the touch screen industrial computer detects the actual pressure value applied to the workpiece being ground and polished;

[0037] By comparing and judging the actual pressure value and the given value, the touch screen industrial computer generates a drive signal and sends it to the servo driver for deviation correction, accurately controlling the displacement action of the drive head to release the deformation of the upper and lower compression springs, so that the actual pressure value is close to the given pressure value in real time, dynamically, accurately and stably;

[0038] When the holding time of the corresponding pressure set value reaches the set time, the program automatically switches to the next segmented pressure set value until the last segmented pressure set value and its holding time are executed.

[0039] When the last segmented pressure setting value and pressure holding time are completed, the drive head automatically returns to the mechanical origin position and stops, and the pressure full closed-loop servo control cycle ends;

[0040] When the cycle end button is pressed, the servo motor drives the upper plate to move to the top position and then stops, so that the planetary wheel and the polished products on it can be unloaded and the processing area can be cleaned, and then the next batch of polished workpieces and their planetary wheels can be loaded;

[0041] In addition to the above-mentioned automatic cycle operation mode, there is also an optional mode of manual operation on the operation panel;

[0042] In order to provide high stability and high precision upper plate pressure, the beneficial effects achieved by the embodiment of the present application are:

[0043] 1. It adopts ball screw transmission, which has low rolling friction coefficient and high transmission efficiency, and helps to improve the accuracy of upper plate pressure control;

[0044] 2. The servo motor servo drive system is adopted. The lifting and pressurizing system components of the upper plate are set on the vertical coaxial line. The driving force does not need to overcome the eccentric load. The mechanical mechanism is symmetrical and balanced, and no stress deformation will be generated due to the eccentric structure, which helps to improve the accuracy and stability of the upper plate pressure control;

[0045] 3. The floating head adopts the compression spring up and down tightening mode, which can bear load in both directions, expand the pressurization range, and can still maintain the continuous action of stable pressurization when the load direction is switched. The structure is simple and reliable, which helps to improve the stability of upper plate pressure control;

[0046] 4. The pressure control adopts a fully closed-loop servo control system, which eliminates the influence of the pressure control accuracy on the fluctuations of the transmission chain error, rotational inertia and system preload torque, and helps to improve the accuracy and stability of the upper plate pressure control;

[0047] 5. The rebound displacement sensor is adopted, so that the rebound displacement of the displacement sensor, the displacement caused by the deformation of the upper and lower compression springs of the floating head, and the displacement of the driving head releasing the compression spring are completely synchronized and equal, so that the rebound displacement sensor and the floating head are combined into an organic whole with a simple and reliable structure; it helps to improve the accuracy and stability of the upper plate pressure control;

[0048] 6. Using the industry-leading Powerlink standard Ethernet real-time fieldbus technology, the real-time cycle time can be as low as <0.1ms, jitter <<1us, high data throughput, and high transmission rate (up to 1000Mbit / s) Gigabit Powerlink application is ready, which helps to improve the accuracy and stability of upper plate pressure control, and also helps to upgrade and expand the potential functions of the equipment in the future, as well as communicate and integrate with other devices, and be included in the smart factory network architecture. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solution of the embodiment of the present application, the drawings required to be used in the embodiment are briefly described as follows:

[0050] Figure 1 is a schematic diagram of the structure of the pressure full closed loop servo control device in the open state

[0051] Figure 2 is a schematic diagram of the structure of the pressure full closed loop servo control device

[0052] Figure 3 is a schematic diagram of the working state of the pressure full closed loop servo control

[0053] Figure 4 is a flow chart of the pressure full-closed servo control method

[0054] Explanation of the reference numerals in the figure: bus controller and IO module (01), lower limit travel switch (02), lower limit travel block (03), upper plate (04), floating head connecting rod (the lower end of which is connected to the ball bearing) (05), rebound displacement sensor (06), floating head (including upper and lower bearing compression springs) (07), drive head (08), anti-rotation guide mechanism (09), fixed crossbeam (10), screw nut (11), ball screw (12), servo motor (13), reduction mechanism (14), upper limit travel switch (15), top position proximity sensor (16), top position sensing boss (17), reduction proximity sensor (18), reduction sensing boss (19), servo drive (20), touch screen industrial computer (21), roller fork (22), drive fork (23), workpiece to be polished and its planetary gear (24), lower plate (25); DETAILED DESCRIPTION

[0055] The following will describe the technical solution in the embodiment of the present application in detail with reference to the accompanying drawings in the embodiment of the present application. In order to improve the accuracy and stability of the pressure applied to the workpiece being polished, the present application proposes a pressure full closed loop servo control device, see Figure 2 , Figure 2 Schematic diagram of the structure of the pressure full closed-loop servo control device provided in the embodiment of the present application is shown; Figure 2As shown, the pressure full-closed loop servo control device comprises: a bus controller and an IO module (01), a lower limit travel switch (02), a lower limit travel block (03), an upper plate (04), a floating head connecting rod (the lower end of which is connected to a ball head bearing) (05), a rebound displacement sensor (06), a floating head (including upper and lower bearing compression springs) (07), a driving head (08), an anti-rotation guide mechanism (09), a fixed crossbeam (10), a screw nut (11), a ball screw (12), a servo motor (13), a reduction mechanism (14), an upper limit travel switch (15), a top position proximity sensor (16), a top position sensing boss (17), a reduction proximity sensor (18), a reduction sensing boss (19), a servo driver (20), a touch screen industrial computer (21), etc.;

[0056] The touch screen industrial computer (21), the bus controller and the IO module (01) and the servo drive (20) are connected to each other by means of a Powerlink cable;

[0057] The touch screen industrial computer (21) sends the drive signal to the servo driver (20) through the bus controller and the IO module (01) based on a pre-written program;

[0058] The servo driver (20) and the servo motor (13) are connected in two lines via a power cable and an encoder cable, so as to realize the current loop, speed loop and position loop control operation of the servo motor (13);

[0059] The servo motor (13) drives the ball screw (12) to rotate via the speed reduction mechanism (14);

[0060] The lead screw nut (11) is matched with the ball screw (12), and the ball screw (12) drives the lead screw nut (11) to convert the rotation torque into a driving force in the vertical direction;

[0061] The lead screw nut (11) is fixedly connected to the upper frame of the driving head (08), and the lower frame of the driving head (08) is connected to the floating head (07) via upper and lower compression springs;

[0062] The driving head (08) and the floating head (07) are both frame-type structures, and the side frame of the driving head (08) is installed in a vertically upward sliding manner in cooperation with the anti-rotation guide mechanism (09);

[0063] The driving head (08) can freely move vertically upward and downward under the combined action of the lead screw nut (11) and the anti-rotation guide mechanism (09).

[0064] The floating head (07) is fitted with the upper and lower end surfaces of the upper and lower bearing compression springs through the inner sides of the upper and lower frames, and the upper and lower bearing compression springs are located on the lower end frame of the driving head (08), so that the floating head can bear loads in both directions, thereby expanding the pressure application range, and can still maintain a continuous action of stable pressure application when the load direction is switched;

[0065] A rebound type displacement sensor (06) is installed between the floating head (07) and the driving head (08);

[0066] Specifically, the rebound displacement sensor (06) is fixed in the floating head connecting rod (05), and its telescopic probe elastically rests on the lower end surface of the driving head (08) to detect the actual displacement of the driving head (08) when releasing or compressing the upper and lower bearing compression springs;

[0067] The floating head (07) is connected to the movable ball head of the ball head bearing through the floating head connecting rod (05), and the ball head bearing seat is fixedly connected to the upper plate (04); all the weight of the upper plate (04) acts on the floating head (07), and all the forces of the floating head (07) are applied to the driving head (08) through the upper and lower compression springs;

[0068] Through the up and down floating of the floating head (07) and the centering universal movement of the ball head bearing, the upper plate (04) realizes universal floating, thereby realizing universal floating flexible processing in which the working surfaces of the upper plate (04) and the lower plate (25) fully fit the upper and lower surfaces of the workpiece to be ground and polished.

[0069] The touch screen industrial computer (21) sends a direction and position command drive signal to the servo driver (20) in an initialization state, controls the servo motor (13) to drive the ball screw (12) to rotate, and the ball screw (12) drives the drive head (08) and the upper plate (04) to move to the set top position;

[0070] Specifically, the top position proximity sensor (16) is arranged at the top position of the moving stroke of the drive head (08) and is used to limit the upper limit of the displacement of the drive head (08) when it moves to the top position in the vertical direction;

[0071] A top position sensing boss (17) matched with a top position proximity sensor (16) is fixed to the upper end of the drive head (08);

[0072] When the driving head (08) moves to the top position, the top position sensing boss (17) senses the top position proximity sensor (16), and the top position proximity sensor (16) sends the sensing signal to the touch screen industrial computer (21) through the I / O module (01), and the touch screen industrial computer (21) controls the servo motor (13) to stop running in real time;

[0073] Furthermore, an upper limit travel switch (15) is arranged at a maximum upper limit position of the moving travel of the drive head (08) and is used to limit the maximum upper limit of the displacement of the drive head (08) moving upward in the vertical direction;

[0074] When the upper plate (04) moves upward and rushes out of the top position due to abnormal interference or unexpected factors, the drive head will overtravel, and the top position sensing boss (17) will push open the normally closed contact of the upper limit travel switch (15), so that the main circuit is powered off and the servo motor (13) stops running, which plays a safety protection role in the case of accidental overtravel of the drive head (08);

[0075] See also Figure 1 , Figure 1 FIG. 1 shows a schematic diagram of the structure of the pressure full closed-loop servo control device in an open state provided in an embodiment of the present application. Figure 1 As shown, when the upper plate (04) stops at the top position, the equipment is in an open state to facilitate loading and unloading of workpieces, cleaning and maintenance of the equipment processing area;

[0076] After the workpiece is ready to be loaded, the touch screen industrial computer (21) issues a work start command to control the servo motor (13) to drive the upper plate (04) to perform fast movement and slow movement in the direction of the lower plate (25);

[0077] Before the upper plate (04) comes into contact with the workpiece being ground and polished, it is obvious that the driving head (08) and the floating head (07) move synchronously with the upper plate (04);

[0078] In the rapid movement stage, the touch screen industrial computer (21) sends a command signal to the servo driver (20), and the servo driver (20) controls the servo motor (13) based on the given speed command signal, so that the driving head (08) drives the floating head (07) and the upper plate (04) to move rapidly and synchronously;

[0079] Furthermore, when entering the slow moving stage, the front end of the deceleration sensing boss (19) first enters the sensing area, the deceleration proximity sensor (18) senses, and the touch screen industrial computer (21) sends a command signal to the servo driver (20). The servo driver (20) controls the servo motor (13) based on the given speed command signal, so that the driving head (08) drives the floating head (07) and the upper plate (04) to move synchronously at a slow speed (creeping speed);

[0080] The distance of the upper plate's rapid moving stroke A is always based on a certain distance G between the roller fork (22) and the driving fork (23), so as to ensure that during the slow moving stroke E, the roller fork (22) automatically guides the driving fork (23) with low buffer and the upper plate (04) achieves low buffer flexible contact when approaching the workpiece (24) to be ground and polished;

[0081] Furthermore, when the rear end of the deceleration sensing boss (19) leaves the sensing area, that is, the sensing signal of the deceleration proximity sensor (18) stops, the servo motor (13) stops running, and the upper plate (04) stops moving. At this position, the upper plate (04) is adjusted so that it just contacts the workpiece (24) to be polished, that is, the current position of the driving head (08) is set as the mechanical origin.

[0082] During the above movement process, the servo driver (20) and the servo motor (13) are provided with speed closed-loop feedback to achieve smooth control of the servo motor (13) in terms of starting, accelerating, maintaining a constant speed, decelerating and stopping.

[0083] When the drive head (08) returns to the mechanical origin and the upper plate (04) stops just touching the workpiece being polished, the touch screen industrial computer (21) sends a cycle start command to the servo driver (20), which triggers the touch screen industrial computer (21) - servo driver (20) - servo motor (13) - ball screw (12) - rebound displacement sensor (06) to enter a pressure full closed loop servo control mode;

[0084] See also Figure 3 , Figure 3 FIG. 4 shows a schematic diagram of the working state of the pressure full closed-loop servo control provided in the embodiment of the present application. Figure 3 As shown, it is obvious that when the upper plate (04) contacts the workpiece (24) being ground and polished, the moving displacement of the driving head (08), the deformation displacement of the compression spring of the floating head (07) and the elastic expansion displacement of the displacement sensor (06) are completely synchronous and equal;

[0085] It can also be explained from this that the process of the driving head (08) moving downward from the mechanical origin position is the process of the upper plate (04) applying pressure to the workpiece (24) being ground and polished; because the spring constant (N / mm) of the upper and lower compression springs of the floating head (07) is constant, the magnitude of the applied pressure is in direct proportion to the magnitude of the displacement of the driving head (08) moving downward from the mechanical origin position;

[0086] In the pressure full closed-loop servo control mode, the touch screen industrial computer (21) sends a driving signal of a given value of the upper plate pressure to the servo driver (20);

[0087] Based on the driving signal of the upper plate pressure given value, the servo driver (20) controls the servo motor (13) to drive the ball screw (12) to rotate precisely, and the ball screw (12) controls the driving head (08) to move precisely up and down, and simultaneously precisely controls the displacement amount caused by the deformation of the upper and lower compression springs of the floating head (07);

[0088] At the same time, the rebound displacement sensor (06) detects in real time the actual displacement of the upper and lower bearing compression springs released or compressed by the drive head (08);

[0089] Corresponding to the actual displacement detected, the rebound displacement sensor (06) outputs a standard analog electrical signal to the touch screen industrial computer (21);

[0090] Based on the linear correspondence between the feedback standard voltage or current analog value and the applied pressure value, the touch screen industrial computer (21) detects the actual pressure value applied to the polishing workpiece (24) in real time;

[0091] After comparing and judging the actual pressure value and the given value, the touch screen industrial computer (21) generates a driving signal in real time and sends it to the servo driver (20) for deviation correction, and accurately controls the displacement action of the drive head (08) to release or compress the deformation of the upper and lower compression springs, so as to achieve the actual pressure value being close to the given pressure value in real time, dynamically, accurately and stably;

[0092] Furthermore, the lower limit travel switch (02) is arranged at the maximum lower limit position of the moving travel of the driving head (08) and is used to limit the maximum lower limit of the downward movement of the driving head (08) in the vertical direction;

[0093] A lower limit travel stopper (03) matched with the lower limit travel switch (02) is fixed at the lower end of the driving head (08);

[0094] When the pressure applied by the upper plate (04) to the workpiece (24) to be polished exceeds the rated pressure value due to abnormal interference or unexpected factors, the drive head will overtravel, and the lower limit travel block (03) will push open the normally closed contact of the lower limit travel switch (02), so that the main circuit is powered off and the servo motor (13) stops running, playing a safety protection role in the case that the drive head (08) accidentally overtravels or the pressure applied to the workpiece (24) to be polished accidentally exceeds the pressure;

[0095] In terms of mechanical structure, the servo motor (13), the reduction mechanism (14), the ball screw (12), the upper limit travel switch (15), the top position proximity sensor (16), the reduction proximity sensor (18), the anti-rotation guide mechanism (09) and the lower limit travel switch (02) are all installed on the fixed crossbeam (10);

[0096] In the driving structure of the entire upper plate lifting and pressurizing system, the rotation center lines of the servo motor (13) end drive wheel, the ball screw (12), the drive head (08), the displacement sensor (06), the floating head (07) and the upper plate (04) are all set on the same axis and arranged vertically up and down, so that the driving force does not need to overcome the eccentric load, the mechanical mechanism is symmetrically balanced, and the stress deformation caused by the eccentric structure is avoided;

[0097] See also Figure 4 , Figure 4The flowchart of the pressure full-closed servo control method provided in the embodiment of the present application is shown. The steps of the method are applied to the pressure full-closed loop servo control device of the present application. Specifically, the pressure full-closed loop servo control method can be executed in the pressure full-closed loop servo control device. The pressure full-closed loop servo control method includes:

[0098] First, according to the thickness of the workpiece to be ground and polished and the adjustable position of the deceleration sensing boss, the mechanical origin of the driving head (08) is set to the position where the upper plate (04) just touches the workpiece to be ground and polished (24), and the maximum upper limit, top position and maximum lower limit of the movement of the driving head (08) are set by the upper limit travel switch (15), the top position proximity sensor (16) and the lower limit travel switch (02);

[0099] Secondly, a program is written through a touch screen industrial computer (21) to determine the displacement and speed of the driving head (08), and to determine the given value of the pressure applied by the upper plate (04) to the workpiece to be polished (24) and the corresponding holding time in multiple stages;

[0100] Specifically, determine the given values ​​F1, F2 ... .Fn of the n segments and the pressurization holding time t1, t2 ... tn and the decompression holding time t(n-1)' ... t2', t1' corresponding to the n segments;

[0101] The number of segments n depends on the magnitude of the applied target pressure and also on the machinability of the workpiece (24) being ground and polished. If the target pressure value is large or the machinability of the workpiece (24) being ground and polished is poor, the number n is large; if the target pressure value is small or the machinability of the workpiece (24) being ground and polished is good, the number n is small; the maximum value of the target pressure is not greater than the rated pressure value of the workpiece (24) being ground and polished;

[0102] like Figure 1 As shown, when the equipment is turned on, the touch screen industrial computer (21) sends a driving signal of direction and position instructions to the servo driver (20) in the initialization state, controls the servo motor (13) to drive the upper plate (04) to the set top position and then stops. At this time, the upper plate (04) is in a raised state to facilitate cleaning and maintenance of the equipment processing area, and to load the polished workpiece and its planetary gear (24);

[0103] In addition, the upper limit travel switch (15) is arranged at the maximum upper limit position of the moving stroke of the drive head (08) and is used to limit the maximum upper limit displacement of the drive head (08) moving upward; when the drive head (08) rushes out of the top position due to abnormal interference or unexpected factors and moves to the upper limit displacement, the top position sensing boss (17) will push open the normally closed contact of the upper limit travel switch (15), so that the main circuit is powered off and the servo motor (13) stops running, thus playing a safety protection role in the case of accidental overtravel of the drive head (08);

[0104] When the workpiece to be polished and its planetary gear (24) are ready to be loaded, a work start button is pressed, and the touch screen industrial computer (21) sends a work start command to control the servo motor (13) to drive the upper plate (04) to perform fast movement and slow movement in the direction of the lower plate (25);

[0105] The specific steps include: the upper plate (04) and the driving head (08) synchronously pass through a fast moving stroke A and then enter a slow moving stroke E, and after a displacement of a distance G, the upper plate roller fork (22) starts to automatically guide the lower end driving fork (23) with low buffering;

[0106] The upper plate (04) and the driving head (08) synchronously move through a slow moving stroke E and then automatically stop at the mechanical origin position, where the upper plate (04) just contacts the workpiece (24) being ground and polished. At this time, the pressure value F0 of the upper plate (04) on the workpiece (24) being ground and polished is close to equal to 0 N.

[0107] Furthermore, in the automatic cycle operation mode, pressing the cycle start button triggers the touch screen industrial computer (21) - servo drive (20) - servo motor (13) - ball screw (12) - rebound displacement sensor (06) to enter the upper plate pressure full closed loop servo control mode;

[0108] like Figure 3 As shown, in the pressure full closed-loop servo control mode, the touch screen industrial computer (21) sends a driving signal of the upper plate (04) pressure set value F1 to the servo driver (20);

[0109] Based on the driving signal of the given pressure value F1 of the upper plate (04), the servo driver (20) controls the servo motor (13) to drive the ball screw (12) to rotate precisely, and the ball screw (12) controls the driving head (08) to move precisely up and down, and precisely controls the displacement amount caused by the deformation of the upper and lower compression springs of the floating head (07);

[0110] At the same time, the rebound displacement sensor (06) detects the actual displacement of the drive head when the upper and lower bearing compression springs are released;

[0111] Corresponding to the actual displacement detected, the rebound displacement sensor (06) outputs a standard analog electrical signal and feeds it back to the touch screen industrial computer (21);

[0112] Based on the proportional linear correspondence between the feedback voltage or current standard analog value and the applied pressure value, the touch screen industrial computer (21) detects the actual pressure value applied to the polishing workpiece (24);

[0113] After comparing and judging the actual pressure feedback value and the given value, the touch screen industrial computer (21) generates a driving signal and sends it to the servo driver (20) for deviation correction, and accurately controls the displacement action of the drive head (08) to release the deformation of the upper and lower bearing compression springs, so as to achieve the actual pressure value being close to the given pressure value F1 in real time, dynamically, accurately and stably;

[0114] When the holding time of the given pressure value F1 reaches t1, the program automatically switches to the next segmented given pressure value F2, until the holding time reaches t2, the program automatically switches to the next segment, until the nth segmented given pressure value Fn and holding time tn are executed;

[0115] Because the pressurization pressure set value Fn is close to or equal to the rated pressure value, when the holding time reaches tn, the program automatically switches to the next step of reverse decompression pressure set value Fn-1, until the holding time reaches t(n-1)', the program automatically switches to the next segment, until the first segment's decompression pressure set value F1 and holding time t1' are executed;

[0116] When the holding time of the first segment's reduced pressure set value F1 reaches t1', the drive head (08) automatically returns to the mechanical origin position and stops, and the pressure full closed-loop servo control cycle ends;

[0117] In addition, the lower limit travel switch (02) is arranged at the maximum lower limit position of the moving travel of the driving head (08) and is used to limit the lower limit of the maximum displacement of the driving head (08) moving downward; when the pressure applied by the upper plate (04) to the workpiece (24) to be polished exceeds the rated pressure value due to abnormal interference or unexpected factors, the driving head (08) will overtravel, and the lower limit travel block (03) will push open the normally closed contact of the lower limit travel switch (02), so that the main circuit is powered off and the servo motor (13) stops running, thus playing a safety protection role in the case that the driving head (08) accidentally overtravels or the pressure applied to the workpiece (24) to be polished accidentally exceeds the pressure;

[0118] When the cycle end button is pressed, the touch screen industrial computer (21) controls the servo motor (13) to drive the upper plate (04) to move to the top position based on the driving signal of the top position displacement given value of the driving head (08). The top position proximity sensor (16) senses and controls the servo motor (13) to stop running, so that the upper plate (04) stops at the top position, so that the planetary wheel and the finished polished workpiece (24) thereon can be removed and the processing area can be cleaned before the next batch of polished workpieces (24) can be loaded.

[0119] In addition to the above-mentioned automatic cycle operation mode, there is also an optional manual operation mode on the operation panel;

[0120] In the manual operation mode, the given pressure value can be infinitely adjusted and controlled by turning the potentiometer knob, and the pressure holding time can also be flexibly set by the timer.

[0121] In summary, the present embodiment provides a pressure full-closed-loop servo control device and a pressure control method thereof, which realizes full-closed-loop servo control of the upper plate (04) pressure through the comprehensive application of a touch screen industrial computer (21), a servo driver (20), a servo motor (13), a ball screw (12), a drive head (08), a rebound displacement sensor (06), a floating head (07), and Powerlink Ethernet real-time field bus technology, thereby effectively improving the stability and accuracy of the upper plate pressure during the grinding / polishing process of silicon wafers or silicon carbide wafers.

[0122] It should be noted that the above is only a preferred implementation mode of the present application, which is used to illustrate the technical solution of the present application rather than to limit it. The protection scope of the present application is not limited to this. Any technician familiar with the technical field can make several improvements and changes without departing from the principles of the present application, and can also combine the above-mentioned technical features in an appropriate manner. These improvements, changes or combinations, or the direct application of the concepts and technical solutions of the present application to other occasions, should be regarded as the protection scope of the present application.

Claims

1. A pressure full-closed loop servo control device, comprising a bus controller and an IO module (01), a lower limit travel switch (02), a lower limit travel block (03), an upper plate (04), a floating head connecting rod (the lower end of which is connected to a ball bearing) (05), a rebound displacement sensor (06), a floating head (including upper and lower bearing springs) (07), a driving head (08), an anti-rotation guide mechanism (09), a fixed crossbeam (10), a screw nut (11), a ball screw (12), a servo motor (13), a speed reduction mechanism (14), an upper limit travel switch (15), a top position proximity sensor (16), a top position sensing boss (17), a speed reduction proximity sensor (18), a speed reduction sensing boss (19), a servo driver (20), a touch screen industrial computer (21), etc.; characterized in that: The touch screen industrial computer (21), the bus controller and the IO module (01) and the servo driver (20) are communicatively connected via a Powerlink cable; the touch screen industrial computer (21) sends a drive signal to the servo driver (20) via the bus controller and the IO module (01) based on a pre-written program; The servo driver (20) and the servo motor (13) are connected in two lines via a power cable and an encoder cable, thereby realizing the current loop, speed loop and position loop control operation of the servo motor (13); The servo motor (13) drives the ball screw (12) to rotate via the speed reduction mechanism (14); the ball screw (12) drives the screw nut (11) to convert the rotational torque into a driving force in the vertical direction; The lead screw nut (11) is connected to the upper frame of the driving head (08), and the lower frame of the driving head (08) is connected to the floating head (07) through upper and lower compression springs; The driving head (08) and the floating head (07) are both frame-type structures, and the side frame of the driving head (08) is installed in a vertically upward sliding manner with the anti-rotation guide mechanism (09); the driving head (08) can move freely up and down under the combined action of the lead screw nut (11) and the anti-rotation guide mechanism (09). The floating head (07) fits the upper and lower end surfaces of the upper and lower compression springs through the inner sides of its upper and lower frames, and the upper and lower compression springs are located on the lower end frame of the driving head (08); a rebound displacement sensor (06) is installed between the floating head (07) and the driving head (08); The rebound displacement sensor (06) is fixed in the floating head connecting rod (05), and its telescopic probe elastically rests on the lower end surface of the driving head (08) to detect the actual displacement of the driving head (08) when releasing or compressing the upper and lower bearing compression springs; The floating head (07) is connected to the movable ball head of the ball head bearing via a floating head connecting rod (05), and the ball head bearing seat is fixedly connected to the upper plate (04); all the weight of the upper plate (04) acts on the floating head (07), and all the forces of the floating head (07) are applied to the driving head (08) via upper and lower compression springs.

2. The pressure full-closed loop servo control device according to claim 1, characterized in that: The touch screen industrial computer (21) sends a direction and position instruction drive signal to the servo driver (20) in an initialization state, controls the servo motor (13) to drive the ball screw (11) to rotate, and the ball screw (11) drives the drive head (08) and the upper plate (04) to move to the set top position; When the driving head (08) moves to the top position, the top position sensing boss (17) senses the top position proximity sensor (16), and the top position proximity sensor (16) sends the sensing signal to the touch screen industrial computer (21) through the I / O module (01), and the touch screen industrial computer (21) controls the servo motor (13) to stop running in real time.

3. The pressure full-closed loop servo control device according to claim 1, characterized in that: The upper limit travel switch (15) is arranged at the maximum upper limit position of the moving travel of the drive head (08) and is used to limit the maximum upper limit of the displacement of the drive head (08) moving upward in the vertical direction; When the drive head (08) moves upward and rushes out of the top position due to abnormal interference or unexpected factors, the drive head (08) will overtravel, and the top position sensing boss (17) will push open the normally closed contact of the upper limit travel switch (15), so that the main circuit is powered off and the servo motor (13) stops running, thus playing a safety protection role in the event of accidental overtravel of the drive head (08).

4. The pressure full-closed loop servo control device according to claim 1, characterized in that: The touch screen industrial computer (21) issues a work start instruction to control the servo motor (13) to drive the upper plate (04) to perform fast movement and slow movement in the direction of the lower plate (25); When entering the slow moving stage, the front end of the deceleration sensing boss (19) first enters the sensing area, the deceleration proximity sensor (18) senses, and the touch screen industrial computer (21) sends a command signal to the servo driver (20). The servo driver (20) controls the servo motor (13) based on the given speed command signal, so that the driving head (08) drives the floating head (07) and the upper plate (04) to move synchronously at a slow speed (crawling speed); so as to realize the low-buffered automatic introduction of the driving fork (23) of the upper plate roller fork (22) and achieve low-buffered flexible contact when the upper plate approaches the workpiece (24) to be polished; When the rear end of the deceleration sensing boss (19) leaves the sensing area, that is, the sensing signal of the deceleration proximity sensor (18) stops, the servo motor (13) stops running, and the upper plate (04) stops moving. At this position, the upper plate (04) is adjusted to just contact the workpiece (24) to be ground, that is, the point where the current drive head (08) is located is set as the mechanical origin. During the above movement process, the servo driver (20) and the servo motor (13) are feedbacked through a closed-loop speed loop to achieve smooth control of the servo motor (13)'s start, acceleration, constant speed, deceleration and stop.

5. The pressure full-closed loop servo control device according to claim 1, characterized in that: In the pressure full closed-loop servo control mode, the touch screen industrial computer (21) sends a driving signal of a pressure set value to the servo driver (20); Based on the driving signal of the upper plate pressure given value, the servo driver (20) controls the servo motor (13) to drive the ball screw (12) to rotate precisely, and the ball screw (12) controls the driving head (08) to precisely release the displacement of the upper and lower compression springs of the floating head (07); At the same time, the rebound type displacement sensor (06) detects in real time the actual displacement of the upper and lower bearing springs released or compressed by the drive head (08); corresponding to the detected actual displacement, the rebound type displacement sensor (06) outputs a standard analog electrical signal to the touch screen industrial computer (21); Based on the linear correspondence between the feedback standard voltage or current analog value and the applied pressure value, the touch screen industrial computer (21) detects the actual pressure value applied to the polished workpiece (24) in real time; After comparing and judging the actual pressure value fed back and the given value, the touch screen industrial computer (21) generates a driving signal in real time and sends it to the servo driver (20) for deviation correction, thereby accurately controlling the displacement action of the drive head (08) to release or compress the deformation of the upper and lower compression springs, so as to achieve the actual pressure value being close to the given pressure value in real time, dynamically, accurately and stably.

6. A pressure full-closed loop servo control device according to claim 1, characterized in that: In the driving structure of the entire upper plate lifting and pressurizing system, the rotation center lines of the servo motor (13) end drive wheel, the ball screw (12), the drive head (08), the displacement sensor (06), the floating head (07) and the upper plate (04) are all set on the same axis and arranged vertically up and down, so that the driving force does not need to overcome the eccentric load, the mechanical mechanism is symmetrically balanced, and the stress deformation caused by the eccentric structure is avoided.

7. A pressure full closed loop servo control method, characterized in that: Applied to the pressure full-closed-loop control device as claimed in claim 1, the pressure full-closed-loop servo control method comprises: Writing a program through the touch screen industrial computer (21) to determine the movement displacement and movement speed of the drive head (08), and determining the given value of the pressure applied by the upper plate (04) to the workpiece to be polished (24) and the corresponding holding time in multiple stages; As described in claim 5, in the pressure full closed-loop servo control mode, the touch screen industrial computer (21) accurately controls the displacement action of the drive head (08) to release the deformation of the upper and lower compression springs, so as to achieve the actual pressure value to be close to the pressure set value in real time, dynamically, accurately and stably; When the holding time of the corresponding pressure set value reaches the set time, the program automatically switches to the next segmented pressure set value until the last segmented pressure set value and its holding time are executed. When the last segmented pressure set value and holding time are completed, the drive head automatically returns to the mechanical origin position and stops, and the pressure full closed-loop servo control cycle ends.

8. The pressure full-closed-loop servo control method according to claim 7, characterized in that: The lower limit travel switch (02) is arranged at the maximum lower limit position of the moving travel of the driving head (08) and is used to limit the lower limit of the maximum displacement of the driving head (08) moving downward; when the pressure applied by the upper plate (04) to the workpiece (24) to be polished exceeds the rated pressure value due to abnormal interference or unexpected factors, the driving head (08) will overtravel, and the lower limit travel block (03) will push open the normally closed contact of the lower limit travel switch (02), so that the main circuit is powered off and the servo motor (13) stops running, thus playing a safety protection role in the case that the driving head (08) accidentally overtravels or the pressure applied to the workpiece (24) to be polished accidentally exceeds the pressure.

9. The pressure full-closed-loop servo control method according to claim 7, characterized in that: The distance of the upper plate's rapid moving stroke A is always based on maintaining a certain distance G between the roller fork (22) and the drive fork (23), so as to ensure that during the slow moving stroke E, the roller fork (22) and the drive fork (23) are automatically introduced into engagement in a low-buffered cross direction, and the upper plate (04) is in low-buffered flexible contact when approaching the workpiece (24) to be ground and polished; at the same time, through the up and down floating of the floating head (07) and the centering universal movement of the ball head bearing, the upper plate (04) is universally floated, thereby achieving universal floating flexible processing in which the working surfaces of the upper plate (04) and the lower plate (25) fully fit the upper and lower surfaces of the workpiece to be ground and polished.

10. The pressure full-closed-loop servo control method according to claim 7, characterized in that: In addition to the above-mentioned automatic cycle operation mode, there is also an optional manual operation mode on the operation panel; in the manual operation mode, the given pressure value can be infinitely adjusted and controlled by turning the potentiometer knob, and the pressure holding time can also be flexibly set by the timer.

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