Flexible servo control mechanism for working pressure of upper disc of double-sided grinding and polishing machine

Abstract

The invention discloses an upper disc working pressure flexible servo control mechanism of a double-sided grinding and polishing machine. The upper disc working pressure flexible servo control mechanism comprises a lifting air cylinder and a movable cantilever beam, and a servo motor, a transmission part of the servo motor, a ball screw, a lead screw nut and the like are installed on a protruding supporting plate of the movable cantilever beam. The lead screw nut is in universal floating connection with the upper disc through a driving head, a pressure spring, a floating head, a floating head connecting rod, a ball head bearing connecting rod, a ball head bearing and a universal shaft; a pressure spring and a displacement sensor are installed between the driving head and the floating head, and the upper disc is meshed with a driving shifting fork below the upper disc in a dynamic floating mode through a roller shifting fork fixed to the upper disc to achieve torque transmission and rotation. Through pneumatic and servo motor segmented stroke control, flexible servo closed-loop control of vertical working pressure of the upper disc is achieved, and flexible high-precision grinding and ultra-precision polishing machining of full attachment of the working surfaces of the upper disc and the lower disc and the upper face and the lower face of a workpiece are achieved through floating transmission of the pressure of the upper disc and the rotating torque.

Description

Technical Field

[0001] The invention relates to the technical field of high-precision grinding machines and ultra-precision polishing machines, and in particular to a flexible servo control mechanism for the working pressure of an upper plate of a double-sided grinding and polishing machine. Background Art

[0002] The double-sided grinding and polishing machine is a surface precision processing equipment in which the upper and lower working surfaces of the upper and lower disks rotate forward and reversely respectively, while the sun gear and the ring gear rotate forward and reversely relative to each other, driving the workpiece to rotate in a planetary manner with the planetary gear. At the same time, the upper and lower surfaces of the workpiece are pressurized by the upper and lower disks, and the surface material of the workpiece is finely removed through the comprehensive scratching action of tiny abrasive particles in the grinding liquid or polishing liquid. In the field of upper disk pressure control technology of high-precision double-sided grinding and polishing machines, the pressure drive sources mainly include pneumatic, hydraulic and electric. Among them, pneumatic lifting and pressurization are more common. The advantages of pneumatic are cleanliness and low cost, but the disadvantages are that the air compression rate is large, and the stability and responsiveness of pressure control are much worse than those of hydraulic and electric, which cannot meet the processing of workpieces with higher technical requirements. According to the special requirements of the precision of some processed workpieces, high-precision double-sided grinding and polishing machines that are electrically driven to lift and control the upper plate pressure through pressure sensors have begun to appear, achieving relatively good results. However, from the perspectives of practicality, cost and pressure control accuracy, there are also the following three shortcomings: 1. The pressure sensor can transmit analog electrical signals through its pressure deformation, but its deformation is very small. When the upper plate begins to contact the workpiece, it is not enough to play a buffering role. It is necessary to add a buffer device to achieve soft contact start and flexible loading, which adds additional complexity and uncertainty to the pressure control process; 2. The upper plate lifting and loading use the same driving mechanism and are located on the outer side of the upper and lower plates. The center of gravity of the working pressure of the upper plate is on the rotation axis of the upper and lower plates. The upper end stroke of the entire upper plate is driven to rise or fall through a cantilever beam or a gantry beam in the middle, and the working pressure is controlled. The control weight includes not only the floating part of the upper plate, but also the heavy support parts such as the cantilever beam or the beam, which proportionally reduces the pressure control responsiveness of the system; at the same time, the power and specifications of the components of the power system and the transmission system are proportionally increased, which additionally increases the manufacturing cost of precision parts. 3. The deformation caused by the eccentric load between the rotation axis of the floating part of the upper plate and the driving force axis of the driving mechanism reduces the servo closed-loop control accuracy. In addition, in terms of the pressure and rotation torque transmission of the upper plate, the non-aligning connection between the upper plate and the pressure transmission part of some double-sided grinding and polishing machines or the non-floating engagement between the upper plate fork and the driving fork will directly affect the safety of the upper plate working pressure control and the processing accuracy of the surface of the workpiece being processed. Summary of the invention

[0003] The purpose of the present invention is to provide a flexible servo control mechanism for the upper plate working pressure of a double-sided grinding and polishing machine in view of the deficiencies in the above-mentioned prior art. Through the segmented stroke control of the cylinder and the servo motor, the pressure sensor is replaced by a displacement sensor and a compression spring to realize vertical flexible servo closed-loop control of the upper plate working pressure, and through the flexible floating transmission of the upper plate pressure and rotational torque, flexible high-precision grinding or ultra-precision polishing processing in which the working surfaces of the upper and lower plates are fully fitted with the upper and lower surfaces of the workpiece is realized.

[0004] To achieve the above technical objectives, the technical solution adopted by the present invention is: a flexible servo control mechanism for the working pressure of the upper plate of a double-sided grinding and polishing machine, comprising a lifting cylinder, a movable cantilever beam, the movable cantilever beam is fixedly connected to the piston rod of the lifting cylinder, and a transmission support, a servo motor, a synchronous belt and a synchronous pulley, a screw bearing and its support, a ball screw, a screw nut, etc. are installed in sequence on the top of the support plate raised by the movable cantilever beam; the lower end of the ball screw is installed on the auxiliary support; the screw nut is fixedly connected to the driving head; an upper guide rod and a lower guide rod are respectively installed on the lower frame of the driving head, and are elastically connected to the floating head through upper and lower compression springs; the floating head is fixedly connected to the floating head connecting rod; a displacement sensor is installed in the inner hole of the floating head connecting rod, and the telescopic probe of the displacement sensor elastically presses against the end face of the lower guide rod, and the lower end of the floating head connecting rod is fixedly connected to the upper end of the ball head bearing connecting rod through a locking nut, and a ball head bearing is installed at the lower end of the ball head bearing connecting rod, and a universal shaft is installed in the inner hole of the ball head bearing. The universal shaft is fixedly connected to the end surface of the central axis of the upper plate, and the upper plate is dynamically engaged with the driving fork below through the roller fork to achieve torque transmission and rotation.

[0005] Furthermore, the total stroke of the upper plate is controlled in sections, and the total stroke includes two sections: the upper end stroke and the end stroke. The lifting part of the entire upper plate is controlled by the lifting cylinder through the movable cantilever beam to achieve rapid rise of the upper end stroke, and fast and slow descent. When the lifting cylinder rises to the top position, the sensing boss senses the proximity sensor of the cylinder top position, and the servo motor is started to raise the drive head to the upper position, so that the upper plate lift reaches the maximum, which is convenient for loading and unloading workpieces, cleaning and maintenance of the equipment processing area; when the lifting cylinder descends to the bottom position, the roller bearing of the upper plate roller fork is just completely and automatically introduced into the upper end of the groove of the drive fork, the sensing boss senses the proximity sensor of the cylinder bottom position, and the servo motor is started to drive the floating part of the upper plate to start the fast forward, slow forward, flexible soft contact with the upper surface of the workpiece and pressure flexible servo control and other sequential actions.

[0006] Furthermore, the driving torque of the servo motor acts on the ball screw through the synchronous belt and the synchronous pulley, and the torque of the ball screw then acts on the screw nut and the driving head to generate an up and down axial thrust, and further acts on the floating head through the compression spring.

[0007] Furthermore, in the above process, the auxiliary support serves as a supporting component for the lower end of the ball screw and also as an anti-rotation and guiding component for the drive head.

[0008] Furthermore, the flexible transmission of the pressure of the upper plate from top to bottom is achieved by the up and down floating of the floating head through the linear bearing seat and the linear bearing on the upper guide rod and the lower guide rod and the universal floating of the ball head bearing; the flexible transmission of the rotational torque of the upper plate is achieved by the cross-direction introduction of the roller fork and the driving fork, and the dynamic floating engagement between the roller bearing and the groove.

[0009] Furthermore, the floating head can slide up and down in a connecting rod guide sleeve through a floating head connecting rod, and the connecting rod guide sleeve is installed in a guide hole of the movable cantilever beam.

[0010] Furthermore, the floating head and the driving head are both frame-type structures, located directly above the upper plate, and the ball screw driving shaft is located directly above the floating head, ensuring that the telescopic probe axis of the sensor, the sliding guide axis of the floating head and the driving axis of the ball screw all coincide with the same upper plate rotation axis, thereby realizing vertical drive and flexible servo closed-loop control of the upper plate working pressure.

[0011] The beneficial effects of the present invention are: 1. The working pressure of the upper plate is controlled by the upper plate-compression spring-displacement sensor-floating head-ball screw-servo motor and other components in a coaxial vertical direction to realize flexible servo closed-loop control, pure mechanical transmission, compact transmission, no eccentric force, faster pressure control response speed and higher accuracy.

[0012] 2. Segmented stroke control. First, the lifting cylinder realizes the rapid rise, rapid and slow descent of the upper end of the heavy-duty integral upper plate through the cantilever beam on the side of the upper plate; then the servo motor realizes the vertical movement of the floating part of the upper plate (such as Figure 7 The precise control of the servo motor and ball screw avoids large strokes, heavy weights and eccentric deformation of the intermediate support, making the upper plate working pressure servo control effect more sensitive, more accurate and more effective.

[0013] 3. The flexible effect is more obvious: First, in the soft contact start when the upper plate begins to contact the workpiece, a compression spring is used for buffering, and the deformation of the compression spring is fed back by the displacement sensor. Under the control of the preset pressure value of the servo motor, the upper plate is in flexible soft contact with the workpiece surface close to zero pressure, ensuring the safe soft start of the workpiece processing; secondly, in the top-down pressure drive of the upper plate, the upper plate universal floating flexible processing is realized through the up and down floating of the floating head and the universal floating of the ball head bearing; in addition, in the rotation torque drive of the upper plate, the roller fork and the drive fork are cross-guided, and the dynamic floating engagement between the roller bearing and the groove further realizes the universal floating flexible processing of the upper and lower plate working surfaces fully fitting the upper and lower surfaces of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The upper plate is in the top position, and the cylinder and the lead screw are fully raised. Figure 2 The upper plate is in the upper position at the bottom, and the lead screw is raised. Figure 3 Schematic diagram of the cross-sectional engagement state between the roller fork and the driving fork Figure 4 The upper plate is at the bottom, and the screw servo is in working state. Figure 5 Schematic diagram of the flexible servo control mechanism for the upper plate working pressure Figure 6 Schematic diagram of the cross-section of the elastic displacement sensor structure of the upper disk floating head Figure 7 Schematic diagram of the floating structure of the upper plate Explanation of the numbers in the figure: 01 lower plate, 02 driving fork, 03 roller bearing, 04 roller fork, 05 lifting cylinder, 07 movable cantilever beam, 09 cylinder bottom proximity sensor, 10 cylinder top proximity sensor, 11 sensing boss, 14 upper plate, 15 universal shaft, 16 ball head bearing connecting rod, 17 screw nut, 18 ball screw, 19 screw bearing and its support, 20 transmission support, 21 synchronous belt and synchronous pulley, 23 servo motor, 24 driving head, 25 screw auxiliary support, 26 ball head bearing, 27 floating head connecting rod, 28 connecting rod guide sleeve, 29 linear bearing, 30 displacement sensor, 31 floating head, 32 compression spring, 33 lower guide rod, 34 upper guide rod, 35 linear bearing seat, 36 locking nut Implementation

[0015] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0016] As shown in Figures 1 to 7, it includes a lifting cylinder (05), a movable cantilever beam (07), the movable cantilever beam (07) is fixedly connected to the piston rod of the lifting cylinder, and a transmission support (20), a servo motor (23), a synchronous belt and a synchronous pulley (21), a screw bearing and its support (19), a ball screw (18), a screw nut (17), etc. are installed in sequence on the top of the raised support plate of the movable cantilever beam (07); the lower end of the ball screw (18) is installed on the auxiliary support (25); the screw nut (17) is fixedly connected to the drive head (24); the lower frame of the drive head (24) is respectively connected to the upper guide rod (34) and the lower guide rod (35). The rod (33) is fixedly connected and elastically connected to the floating head (31) through a compression spring (32) that is tightened up and down; the floating head (31) is fixedly connected to the floating head connecting rod (27); a displacement sensor (30) is installed in the inner hole of the floating head connecting rod (27), and the telescopic probe of the displacement sensor (30) elastically presses against the end surface of the lower guide rod (33); the lower end of the floating head connecting rod (27) is fixedly connected to the upper end of the ball bearing connecting rod (16) through a locking nut (36); the lower end of the ball bearing connecting rod (16) is installed with a ball bearing (26), and a universal shaft (15) is installed in the inner hole of the ball bearing (26). The universal shaft (15) is fixedly connected to the end surface of the central axis of the upper plate (14), and the upper plate (14) is dynamically engaged with the driving fork (02) below through the roller fork (04) to realize torque transmission and rotation.

[0017] As shown in FIG. 1 , the total stroke of the upper plate (14) is controlled in two sections, and the total stroke (=A) includes two sections, the upper end stroke (=AET) and the end stroke (=ET) (where T = the thickness of the workpiece being processed). The entire upper plate can be raised and lowered by the lifting cylinder (05) through the movable cantilever beam (07) to achieve the upper end stroke (=AET). When the lifting cylinder (05) rises to the top position, the sensing boss (11) senses the cylinder top position proximity sensor (10), and the servo motor (23) is started to control the drive head (24) to rise to the upper position, so that the upper plate lift (=A) reaches the maximum, so as to facilitate the loading and unloading of workpieces, cleaning and maintenance of the equipment processing area; as shown in Figures 2 and 4, when the lifting cylinder (05) descends to the bottom position, the roller bearing (03) of the upper plate roller fork (04) is just completely and automatically introduced into the upper end of the groove of the drive fork (02), the sensing boss (11) senses the cylinder bottom position proximity sensor (09), and the servo motor (23) is started to drive the floating part of the upper plate (as shown in Figure 7) to start the fast forward, slow forward, flexible soft contact with the upper surface of the workpiece and pressure flexible servo control and other sequential actions.

[0018] As shown in FIG5 , the driving torque of the servo motor (23) acts on the ball screw (18) through the synchronous belt and synchronous pulley (21), and the torque of the ball screw (18) further acts on the screw nut (17) and the drive head (24) to generate an up and down axial thrust, and further acts on the floating head (31) through the compression spring (32).

[0019] As shown in FIG. 6 , as the spring deforms, the floating head (31) freely floats up and down on the upper guide rod (34) and the lower guide rod (33) through the linear bearing seat (35) and the linear bearing (29) fixed thereon, and its floating amount is equal to the deformation of the spring (32). The deformation of the spring (32) is proportional to the axial thrust. The dynamic deformation of the spring (32) is converted into an electrical signal in real time through the displacement sensor (30) and fed back to the PLC and servo controller in the electrical control cabinet. The servo controller controls the servo motor to drive the ball screw to realize the flexible servo closed-loop control of the working pressure of the upper plate. In addition, in the above process, the auxiliary support (25) serves as the support component of the lower end of the ball screw (18) and also serves as the anti-rotation and guide component of the drive head (24).

[0020] As shown in FIG. 6 , the flexible transmission of the pressure of the upper plate ( 14 ) from top to bottom is achieved by the dynamic superposition of the up and down floating of the floating head ( 31 ) and the universal floating of the ball bearing ( 26 ).

[0021] As shown in Figure 3, the flexible transmission of the rotational torque of the upper plate (14) is cross-guided by the roller fork (04) and the driving fork (02), and is realized by the dynamic floating engagement between the roller bearing (03) and the groove. The upper plate (14) can rotate freely on the XX axis and the YY axis at the same time. When the workpiece is subjected to the pressure of the upper plate and the rotational torque of the upper plate, it is ensured that the upper plate (14) can float and rotate freely along with the lower plate (01) and the workpiece, thereby realizing flexible high-precision grinding and ultra-precision polishing processing in which the working surfaces of the upper plate (01) and the lower plate (14) are fully fitted with the upper and lower surfaces of the workpiece.

[0022] In addition, the floating head (31) and the driving head (24) are both frame-type structures, located directly above the upper plate (14), and the driving shaft of the ball screw (18) is located directly above the floating head (31), ensuring that the telescopic probe axis of the sensor (30), the sliding guide axis of the floating head (31) and the driving thrust axis of the ball screw (18) all coincide with the same upper plate rotation axis, thereby realizing vertical drive and flexible servo closed-loop control of the upper plate working pressure.

Claims

1. A flexible servo control mechanism for the working pressure of the upper plate of a double-sided grinding and polishing machine, comprising a lifting cylinder (05) and a movable cantilever beam (07), characterized in that: The movable cantilever beam (07) is fixedly connected to the piston rod of the lifting cylinder, and a transmission support (20), a servo motor (23), a synchronous belt and a synchronous pulley (21), a screw bearing and its support (19), a ball screw (18), a screw nut (17), etc. are installed in sequence on the top of the raised support plate of the movable cantilever beam (07); the lower end of the ball screw (18) is installed on the auxiliary support (25); the screw nut (17) is fixedly connected to the driving head (24); the lower frame of the driving head (24) is respectively fixedly connected to the upper guide rod (34) and the lower guide rod (33), and is connected to the upper guide rod (34) and the lower guide rod (33) by the upper guide rod (34). The lower compression spring (32) is elastically connected to the floating head (31); the floating head (31) is fixedly connected to the floating head connecting rod (27); a displacement sensor (30) is installed in the inner hole of the floating head connecting rod (27); the telescopic probe of the displacement sensor (30) elastically presses against the end surface of the lower guide rod (33); the lower end of the floating head connecting rod (27) is fixedly connected to the upper end of the ball bearing connecting rod (16) through a locking nut (36); the lower end of the ball bearing connecting rod (16) is installed with a ball bearing (26); a universal shaft (15) is installed in the inner hole of the ball bearing (26). The universal shaft (15) is fixedly connected to the end surface of the central axis of the upper plate (14); the upper plate (14) is dynamically engaged with the driving fork (02) below through the roller fork (04) to realize torque transmission and rotation.

2. The upper plate working pressure flexible servo control mechanism of the double-sided grinding and polishing machine according to claim 1 is characterized in that: The entire upper plate liftable part is lifted by the lifting cylinder (05) from the outer sides of the upper and lower plates through the movable cantilever beam (07) to achieve the rapid rise of the upper end stroke, and the rapid and slow descent. When the lifting cylinder (05) rises to the top position, the sensing boss (11) senses the cylinder top position proximity sensor (10), and the servo motor (23) is started to make the drive head (24) also rise to the upper position, so that the upper plate (14) reaches the maximum lift, as shown in Figure 1; when the lifting cylinder (05) descends to the bottom position, the roller bearing (03) of the upper plate roller fork (04) is just completely and automatically introduced into the upper end of the groove of the drive fork (02), the sensing boss (11) senses the cylinder bottom position proximity sensor (09), and the servo motor (23) is started to drive the floating part of the upper plate (as shown in Figure 7) to start the fast forward, slow forward, flexible soft contact with the upper surface of the workpiece and pressure flexible servo control and other sequential actions.

3. The upper plate working pressure flexible servo control mechanism of the double-sided grinding and polishing machine according to claim 1 is characterized in that: The driving torque of the servo motor (23) acts on the ball screw (18) through the synchronous belt and the synchronous pulley (21), and the torque of the ball screw (18) further acts on the screw nut (17) and the drive head (24) to generate an up and down axial thrust, and further acts on the floating head (31) through the compression spring (32).

4. The upper plate working pressure flexible servo control mechanism of the double-sided polishing machine according to claim 3 is characterized in that: The auxiliary support (25) serves as a supporting component for the lower end of the ball screw (18) and also as an anti-rotation and guiding component for the drive head (24).

5. The upper plate working pressure flexible servo control mechanism of the double-sided grinding and polishing machine according to claim 1 is characterized in that: The flexible transmission of the pressure of the upper plate (14) from top to bottom is achieved by the floating head (31) floating up and down on the upper guide rod (34) and the lower guide rod (33) through the linear bearing seat (35) and the linear bearing (29) and the universal floating of the ball head bearing (26); the flexible transmission of the rotational torque of the upper plate (14) is achieved by the cross-direction introduction of the roller fork (04) and the driving fork (02), and the dynamic floating engagement between the roller bearing (03) and the groove.

6. The upper plate working pressure flexible servo control mechanism of the double-sided polishing machine according to claim 1 is characterized in that: The floating head (31) can slide up and down in a connecting rod guide sleeve (28) through a floating head connecting rod (27), and the connecting rod guide sleeve (28) is installed in a guide hole of a movable cantilever beam (07).

7. The upper plate working pressure flexible servo control mechanism of the double-sided grinding and polishing machine according to claim 1 is characterized in that: The floating head (31) and the driving head (24) are both frame-type structures, located directly above the upper plate (14), and the driving shaft of the ball screw (18) is located directly above the floating head (31), ensuring that the telescopic probe axis of the sensor (30), the sliding guide axis of the floating head (31) and the driving thrust axis of the ball screw (18) all coincide with the same upper plate rotation axis, thereby realizing vertical drive and flexible servo closed-loop control of the upper plate working pressure.

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