Intelligent linkage type drilling machine high-position clamping device

Abstract

The present application relates to the technical field of machining equipment, and more particularly to an intelligent linkage type drilling machine high-station clamping device, comprising: a bearing mechanism, a clamping mechanism, a driving mechanism, a sensing and detecting unit and a control unit; the sensing and detecting unit at least comprises a spindle power / torque sensor for acquiring cutting energy consumption data of the spindle of the drilling machine during the machining process; the control unit is in communication connection with the driving mechanism, the sensing and detecting unit and the spindle control system of the drilling machine respectively; the control unit is configured to: based on the cutting energy consumption data, calculate the internal stress release rate that has been completed in the current machining process; according to the internal stress release rate, decide the loosening timing of the clamping mechanism; through data interaction with the spindle control system of the drilling machine, the present application realizes real-time sensing of the cutting process, and dynamically adjusts the clamping state and loosening timing accordingly, thereby overcoming the problems of clamping force and cutting vibration coupling and residual stress release lag, and improving machining precision and efficiency.

Description

Technical Field

[0001] This invention relates to the field of machining equipment technology, and in particular to an intelligent linkage high-position clamping device for drilling machines. Background Technology

[0002] In the field of machining, drilling machines are commonly used hole-making equipment. For high-precision, high-volume drilling operations, the clamping and positioning accuracy and stability of the workpiece directly determine the machining quality. Existing high-position drilling machine clamping devices mostly use hydraulic, pneumatic, or servo motor drives, clamping the workpiece through fixed or manually adjustable pressure plates, V-blocks, and other mechanisms. To improve the degree of automation, existing technologies have introduced programmable logic controllers (PLCs), realizing simple time-sequence linkage control of "clamping in place - starting the spindle - drilling completed - spindle retraction - releasing the fixture".

[0003] However, in practical applications, especially when drilling thin-walled, irregularly shaped workpieces (such as automotive engine cylinder heads, aerospace structural components, and medical implants) with high precision, the existing technologies described above exhibit dynamic changes in spindle cutting force during the drilling process, resulting in high-frequency cutting vibrations. Traditional rigid clamping methods cannot adapt to these dynamic changes: if excessive clamping force is used to suppress vibration, it can easily cause deformation of the thin-walled workpiece during clamping, leading to springback after release and affecting dimensional accuracy; if the clamping force is reduced to minimize deformation, the workpiece is prone to regenerative chatter under the cutting force, resulting in excessive hole wall roughness and shortened tool life; simultaneously, the workpiece ( Especially for heat-treated or pre-stretched metal parts, residual stress exists inside; the drilling process removes some material, disrupting the original stress balance and causing stress redistribution; the existing linkage logic only releases the clamp immediately after drilling is completed, at which point the stress release process inside the workpiece is not yet complete, and the workpiece will undergo instantaneous or slow deformation after losing clamping constraints, resulting in out-of-tolerance position and perpendicularity of the machined holes and a high scrap rate; moreover, the clamping surfaces of traditional clamps are mostly flat or regular curved surfaces, which are difficult to perfectly fit the surface of irregularly shaped workpieces, causing the clamping force to concentrate in a local area, which not only aggravates workpiece deformation but may also damage the workpiece surface.

[0004] Therefore, how to enable the clamping device to sense the state of the cutting process in real time, dynamically adjust the clamping characteristics, and release the workpiece at the appropriate time has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In order to overcome the problems of clamping force coupling with cutting vibration and residual stress release delay leading to accuracy loss in existing drilling machine high-position clamping devices.

[0006] The technical solution of this invention is: an intelligent linkage high-position clamping device for a drilling machine, comprising:

[0007] A support mechanism for placing workpieces; A clamping mechanism, disposed on the bearing mechanism, is used to apply clamping force to the workpiece; A drive mechanism, connected to the clamping mechanism, is used to drive the clamping mechanism to perform clamping or releasing actions; The sensing and detection unit includes at least a spindle power / torque sensor for acquiring cutting energy consumption data of the drilling spindle during the machining process; The control unit is communicatively connected to the drive mechanism, the sensing and detection unit, and the spindle control system of the drilling machine, respectively. The control unit is configured as follows: Receives cutting energy consumption data in real time from the spindle power / torque sensor; Based on the cutting energy consumption data, calculate the internal stress release rate that has been completed in the current machining process; The timing for releasing the clamping mechanism is determined based on the internal stress release rate.

[0008] Preferably, during the drilling process, the spindle drives the workpiece or tool to rotate and feed, and the electrical power consumed is related to the cutting force and cutting speed. The spindle power / torque sensor collects this energy consumption data in real time and transmits it to the control unit. The control unit maps the accumulated cutting energy consumption to the progress index of the internal stress release of the workpiece material, i.e., the internal stress release rate, through a built-in algorithm. When the drilling reaches the predetermined depth, the control unit does not immediately execute the release command, but judges based on the current internal stress release rate: if the release rate has reached the preset standard, it indicates that the internal stress of the workpiece has basically reached a new equilibrium, and release is allowed at this time; if the release rate is insufficient, release is postponed or other auxiliary programs are executed; thus solving the problem of deformation after machining caused by incomplete stress release.

[0009] Preferably, the clamping mechanism includes an intelligent clamp that contacts the workpiece, the intelligent clamp including a rigid back plate and a flexible pad disposed on the side of the rigid back plate facing the workpiece; The flexible liner is filled with magnetorheological fluid and has an embedded electromagnetic coil array. The control unit is connected to the electromagnetic coil array and configured to adjust the apparent viscosity of the magnetorheological fluid by adjusting the current of the electromagnetic coil array, thereby adjusting the stiffness of the contact surface between the smart fixture and the workpiece.

[0010] Preferably, a pressure sensor array is also embedded in the flexible pad, and the pressure sensor array is connected to the control unit to monitor the pressure distribution on the contact surface between the intelligent fixture and the workpiece in real time.

[0011] Preferably, the control unit is further configured as follows: When the clamping mechanism performs the clamping action, a first current is applied to the electromagnetic coil array to make the magnetorheological fluid in a low viscosity state. Based on the feedback from the pressure sensor array, the drive mechanism is controlled to drive the intelligent fixture to fit the workpiece until the detection value of the pressure sensor array reaches the preset uniformity condition. In response to the homogeneity condition being satisfied, a second current is applied to the electromagnetic coil array to solidify the magnetorheological fluid, wherein the second current is greater than the first current.

[0012] Preferably, the control unit is further configured as follows: During the drilling process of the drilling machine spindle, the instantaneous torque data fed back by the spindle power / torque sensor is received in real time; Extract the fluctuation characteristics of the instantaneous torque data; When the amplitude of the wave characteristic exceeds a preset threshold, a pulsating current associated with the frequency of the wave characteristic is applied to the electromagnetic coil array.

[0013] Preferably, the control unit is configured to calculate the internal stress release rate based on the cutting energy consumption data, specifically including: Calculate the integral value of cutting work based on the cutting energy consumption data; The integral value of the cutting work is compared with the preset stress relief model to obtain the internal stress relief rate of the current machining completed.

[0014] Preferably, the control unit is configured to determine the release timing of the clamping mechanism based on the internal stress release rate, specifically including: The internal stress release rate is compared with a first preset threshold. If the internal stress release rate reaches or exceeds the first preset threshold, the drive mechanism is controlled to perform a release action.

[0015] Preferably, the control unit is further configured as follows: If the internal stress release rate is lower than the first preset threshold, the stress release auxiliary program is triggered. The stress relief assistance procedure includes: The drive mechanism is controlled to adjust the clamping force of the clamping mechanism to a second preset value; Control the drilling machine spindle to perform at least one idle stroke or a small cutting stroke on the machined hole with preset low-speed feed parameters; During this period, data from the spindle power / torque sensor continues to be received until stress release is determined to be complete.

[0016] Preferably, the control unit determines that stress release is complete based on the following: during the idle stroke or micro-cutting stroke, the cutting power detected by the spindle power / torque sensor drops below a third preset threshold.

[0017] Preferably, the electromagnetic coil array consists of multiple independently controllable coil units, which are arranged in an array within the flexible pad.

[0018] The beneficial effects of this invention are: 1. This invention introduces the internal stress release rate as the core basis for deciding the release of the clamping mechanism. By monitoring the spindle cutting energy consumption in real time, it quantitatively assesses the release process of the internal stress of the workpiece and allows release only after the stress reaches equilibrium. This effectively avoids workpiece springback deformation caused by incomplete stress release and improves the yield of high-precision thin-walled parts. It also realizes deep linkage based on the physical state of the workpiece and solves the problem of deformation after processing. 2. By employing a magnetorheological fluid intelligent fixture and linking it with the spindle torque fluctuation characteristics, this invention transforms the clamping device from a passive, constant support structure into an intelligent unit with active vibration absorption capabilities. When chatter symptoms are detected, the control unit applies a pulsating current related to the chatter frequency to the fixture, causing the fixture to generate a dynamic damping effect. This dissipates the vibration energy before it is transmitted to the workpiece, ensuring the stability of the machining process, improving the surface quality of the hole and tool life, achieving adaptive adjustment of clamping stiffness, and effectively suppressing cutting chatter. 3. Utilizing the rheological properties of magnetorheological fluid, this invention allows the clamp to adapt to the workpiece surface in a soft state during the initial clamping stage, and ensures uniform pressure through a pressure sensor array, eliminating local stress concentration. After achieving precise adhesion, the current is increased to solidify the workpiece, providing sufficient processing rigidity. This solution solves the problem of uneven clamping of irregularly shaped workpieces, expands the processing range of drilling machines, and realizes adaptive non-destructive clamping of complex curved surfaces. 4. For difficult-to-machine materials with high internal stress, this invention actively guides and confirms the completion of workpiece stress release by performing a controlled micro-cutting process after drilling and monitoring the changes in cutting power in real time. This ensures that even in the machining of high-stress materials, the workpiece can maintain stable geometric accuracy after being released from the clamp. Attached Figure Description

[0019] Figure 1 The diagram shown is a three-dimensional structural schematic of the intelligent linkage drilling machine high-position clamping device of the present invention. Figure 2 The diagram shown is a top view of the intelligent linkage drilling machine high-position clamping device of the present invention. Figure 3The diagram shown is a cross-sectional schematic of the intelligent linkage drilling machine high-position clamping device of the present invention. Explanation of reference numerals in the attached drawings: 1. Bearing mechanism; 2. Clamping mechanism; 21. Rigid back plate; 22. Flexible pad; 23. Electromagnetic coil array; 24. Pressure sensor array; 3. Drive mechanism. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Example 1: Please see Figure 1 , Figure 2 and Figure 3 This invention provides an embodiment: an intelligent linkage high-position clamping device for a drilling machine, comprising: Support mechanism 1 is used to place the workpiece; The clamping mechanism 2 is mounted on the bearing mechanism 1 and is used to apply clamping force to the workpiece; Drive mechanism 3 is connected to clamping mechanism 2 and is used to drive clamping mechanism 2 to perform clamping or releasing actions; The sensing and detection unit includes at least a spindle power / torque sensor for acquiring cutting energy consumption data of the drilling spindle during the machining process; The control unit is communicatively connected to the drive mechanism 3, the sensing and detection unit, and the spindle control system of the drilling machine. The control unit is configured as follows: Receives real-time cutting energy consumption data from the spindle power / torque sensor; Based on cutting energy consumption data, calculate the internal stress release rate that has been completed in the current machining process; The timing for releasing the clamping mechanism 2 is determined based on the internal stress release rate.

[0022] During drilling, the spindle drives the workpiece or tool to rotate and feed, consuming electrical power related to cutting force and cutting speed. The spindle power / torque sensor collects this energy consumption data in real time and transmits it to the control unit. The control unit uses a built-in algorithm to map the accumulated cutting energy consumption to an indicator of the progress of stress release within the workpiece material, namely the internal stress release rate. When the drilling reaches the predetermined depth, the control unit does not immediately execute the release command, but judges based on the current internal stress release rate: if the release rate has reached the preset standard, it indicates that the internal stress of the workpiece has basically reached a new equilibrium, and release is allowed at this time; if the release rate is insufficient, release is postponed or other auxiliary programs are executed; thus solving the problem of post-processing deformation caused by incomplete stress release.

[0023] Furthermore, the clamping mechanism 2 includes an intelligent clamp that contacts the workpiece. The intelligent clamp includes a rigid back plate 21 and a flexible pad 22 disposed on the rigid back plate 21 facing the workpiece. The flexible liner 22 is filled with magnetorheological fluid and has an embedded electromagnetic coil array 23. The control unit is connected to the electromagnetic coil array 23 and configured to change the apparent viscosity of the magnetorheological fluid by adjusting the current of the electromagnetic coil array 23, thereby adjusting the stiffness of the contact surface between the smart fixture and the workpiece.

[0024] Among them, magnetorheological fluid is a smart material whose rheological properties (such as shear yield stress) can be changed rapidly and reversibly with the change of the applied magnetic field strength; the electromagnetic coil array 23 generates a magnetic field after being energized, and the magnetic field strength is controlled by the magnitude of the current; when the current is small, the magnetorheological fluid is in a low-viscosity fluid state, and the flexible pad 22 has good conformability; when the current increases, the magnetic particles in the magnetorheological fluid form a chain structure along the direction of the magnetic field, causing its apparent viscosity to rise sharply and exhibit a solid-like state, thereby providing stable support stiffness; by adjusting the current, the control unit can realize stepless adjustment of the stiffness of the clamping surface, so that it can adapt to the stiffness requirements of different processing stages.

[0025] Furthermore, a pressure sensor array 24 is also embedded in the flexible pad 22. The pressure sensor array 24 is connected to the control unit and is used to monitor the pressure distribution on the contact surface between the smart fixture and the workpiece in real time.

[0026] The pressure sensor array 24 consists of multiple miniature pressure sensors arranged at a certain interval, which can sense the pressure value at each point on the contact surface. These data are fed back to the control unit in real time for closed-loop control of the uniformity and magnitude of the clamping force, avoiding local pressure concentration.

[0027] Furthermore, the control unit is also configured as follows: When the clamping mechanism 2 performs the clamping action, a first current is applied to the electromagnetic coil array 23 to make the magnetorheological fluid in a low viscosity state. Based on the feedback from the pressure sensor array 24, the control drive mechanism 3 drives the intelligent fixture to fit the workpiece until the detection value of the pressure sensor array 24 reaches the preset uniformity condition. In response to the uniformity condition being met, a second current is applied to the electromagnetic coil array 23 to solidify the magnetorheological fluid, and the second current is greater than the first current.

[0028] In this embodiment, the first step is to apply a small current (first current) to soften the flexible pad 22, and the drive mechanism 3 pushes the clamp with low pressure, so that it adaptively conforms to the complex curved surface of the workpiece under the guidance of the pressure sensor array 24 until the readings of each sensor tend to be consistent, indicating that the clamp has been fully conformed and the pressure distribution is uniform. The second step is to quickly apply a larger current (second current) after the conformation is completed, so that the magnetorheological fluid is instantly solidified, "locking" the precise contour obtained by conformal fitting into a rigid support, thereby providing the stable rigidity required for subsequent processing while ensuring uniform clamping.

[0029] Furthermore, the control unit is also configured as follows: During the drilling process of the drill press spindle, the instantaneous torque data fed back by the spindle power / torque sensor is received in real time; Extract the fluctuation characteristics of instantaneous torque data; When the amplitude of the wave characteristic exceeds a preset threshold, a pulsating current associated with the frequency of the wave characteristic is applied to the electromagnetic coil array 23.

[0030] When chatter occurs, the spindle torque signal exhibits periodic fluctuations at a specific frequency. The control unit analyzes the torque signal in real time using algorithms such as Fast Fourier Transform (FFT) to extract the amplitude and dominant frequency of the fluctuations. When it is determined that chatter is about to occur or has already occurred, the control unit generates a pulsating current with a frequency close to or in a specific proportion to the dominant frequency of the fluctuations and applies it to the electromagnetic coil array 23. This pulsating current causes the magnetorheological fluid to undergo a periodic "solidification-softening" change in a very short time, forming a dynamic damper that matches the chatter frequency, thereby absorbing and dissipating vibration energy and suppressing the further development of chatter. This scheme achieves active and adaptive suppression of cutting vibration.

[0031] Furthermore, the control unit is configured to calculate the internal stress release rate based on cutting energy consumption data, specifically including: Calculate the integral value of cutting work based on cutting energy consumption data; The integral value of the cutting work is compared with the preset stress relief model to obtain the internal stress relief rate of the current machining.

[0032] Among them, cutting work is the accumulation of cutting force over displacement, which is directly related to the volume of the removed material and the energy consumed by the plastic deformation of the material; the control unit integrates the product of the real-time acquired spindle power P(t) and feed rate v_f(t) over time to obtain the cutting work W=∫P(t)·v_f(t)dt; for specific materials and processes, a calibration model of "cutting work-stress release rate" can be established through preliminary experiments (for example, it can be expressed as R=f(W)); by looking up a table or calculating a function, the real-time calculated cutting work W can be mapped to the current internal stress release rate R.

[0033] Furthermore, the control unit is configured to determine the timing of the release of the clamping mechanism 2 based on the internal stress release rate, specifically including: The internal stress release rate is compared with a first preset threshold. If the internal stress release rate reaches or exceeds the first preset threshold, the control drive mechanism 3 will perform a release action.

[0034] The first preset threshold (e.g., 90%) is an empirical value, indicating that when the stress release reaches this proportion, the residual deformation of the workpiece after release is acceptable. When drilling is completed and the calculated R value meets the conditions, the control unit determines that the workpiece is basically stable inside, and then instructs the drive mechanism 3 to unload the clamping force to complete the release action.

[0035] Furthermore, the control unit is also configured as follows: If the internal stress release rate is lower than the first preset threshold, the stress release auxiliary program is triggered. Stress relief assistance procedures include: The control drive mechanism 3 adjusts the clamping force of the clamping mechanism 2 to the second preset value; Control the drilling machine spindle to perform at least one idle stroke or a small cutting stroke on the machined hole with preset low-speed feed parameters; During this period, data from the spindle power / torque sensor continues to be received until stress release is determined to be complete.

[0036] When the stress release is insufficient at the end of drilling, the system activates an auxiliary program. First, the clamping force is appropriately reduced (to a second preset value, such as 80% of the original clamping force) to provide the workpiece with a small deformation space while maintaining its positioning. Then, the spindle (without cutting fluid or with micro-cutting) is instructed to re-enter the machined hole at an extremely low speed and feed rate. This process itself involves a very small amount of cutting, but it is sufficient to release the residual stress inside the workpiece and eliminate the small deformation through micro-cutting, guiding the workpiece to a new stress balance state.

[0037] Furthermore, the control unit determines that stress release is complete based on the following criteria: during the idle stroke or micro-cutting stroke, the cutting power detected by the spindle power / torque sensor drops below the third preset threshold.

[0038] In the stress relief auxiliary program, when the internal stress of the workpiece is still being released, even if the feed rate is extremely small, the tool will bear a small cutting force due to the slight deformation of the workpiece, which is reflected in the slight fluctuation of the spindle power. As the stress is gradually released, the workpiece tends to stabilize, and this small cutting force will approach zero. Therefore, the real-time monitored power value is compared with a threshold close to zero (the third preset threshold). When the power is continuously lower than the threshold, it can be determined that the stress relief process has been basically completed.

[0039] Furthermore, the electromagnetic coil array 23 consists of multiple independently controllable coil units, which are arranged in an array within the flexible pad 22.

[0040] By designing the coils as independently controlled array units, local fine adjustment of the magnetorheological fluid stiffness can be achieved. For example, a higher frequency pulsating current can be applied near the cutting area to enhance the vibration absorption effect, while a constant stiffness can be maintained far from the cutting area to ensure overall support stability. This distributed control further enhances the adaptability and intelligence of the fixture.

[0041] Through the above steps, this invention introduces the internal stress release rate as the core basis for deciding the release of the clamping mechanism 2. By monitoring the spindle cutting energy consumption in real time, the release process of the internal stress of the workpiece is quantitatively evaluated, and release is only allowed after the stress reaches equilibrium. This effectively avoids workpiece springback deformation caused by incomplete stress release, and improves the yield of high-precision thin-walled parts. It also achieves deep linkage based on the physical state of the workpiece, solving the problem of deformation after processing. By using a magnetorheological fluid intelligent fixture and linking it with the spindle torque fluctuation characteristics, this invention transforms the clamping device from a passive, constant support structure into an intelligent unit with active vibration absorption capability. When chatter signs are detected, the control unit applies a pulsating current related to the chatter frequency to the fixture, causing the fixture to generate a dynamic damping effect, thereby dissipating the vibration energy before it is transmitted to the workpiece, ensuring the stability of the processing. Qualitatively, this invention improves the surface quality of the hole and tool life, achieves adaptive adjustment of clamping stiffness, and effectively suppresses cutting chatter. Utilizing the rheological properties of magnetorheological fluid, the fixture adapts to the workpiece surface in a soft state during the initial clamping stage, and the pressure sensor array 24 ensures uniform pressure, eliminating local stress concentration. After achieving precise fit, the current is increased to solidify it, providing sufficient machining stiffness. This solution solves the problem of uneven clamping of irregularly shaped workpieces, expands the machining range of drilling machines, and achieves adaptive non-destructive clamping of complex curved surfaces. For difficult-to-machine materials with high internal stress, this invention actively guides and confirms the completion of workpiece stress release by performing a controlled micro-cutting process after drilling and monitoring changes in cutting power in real time, ensuring that the workpiece maintains stable geometric accuracy even after being released from clamping, even in the machining of high-stress materials.

[0042] Example 2: Optionally, this embodiment provides an intelligent linkage high-position clamping device for drilling machines.

[0043] The device includes: Supporting mechanism 1: It is a base fixed on the drilling machine worktable, with a flat supporting surface, used to place the workpiece to be processed. In this embodiment, the workpiece is an aluminum alloy engine cylinder head. Clamping mechanism 2: includes two intelligent clamps symmetrically arranged on both sides of the bearing mechanism 1; each intelligent clamp further includes: Rigid backplate 21: Made of high-strength aluminum alloy, it is connected to the drive mechanism 3; Flexible gasket 22: Adhesive to the side of the rigid back plate 21 facing the workpiece; the flexible gasket 22 is made of elastic rubber sealing bladder and filled with MRF-140CG magnetorheological fluid (zero field viscosity 0.3 Pa·s, saturated shear stress 50 kPa); an electromagnetic coil array 23 and a pressure sensor array 24 are embedded in the flexible gasket 22. Electromagnetic coil array 23: It consists of multiple planar spiral coil units arranged in a grid pattern with a spacing of 10mm×10mm. Each coil unit can control the current (0-2 A) through an independent drive circuit, with a response time of <5ms. Pressure sensor array 24: It adopts a thin-film piezoresistive sensor with a range of 0-1MPa and an accuracy of 0.5%FS. It is also distributed in a grid pattern to sense the pressure value at each point on the contact surface in real time. Drive mechanism 3: A precision ball screw pair driven by a servo motor is connected to the rigid back plate 21; the servo motor has a built-in encoder, which can realize precise control of the clamping position and closed-loop adjustment of the clamping force, with a maximum clamping force of 5000N and a positioning accuracy of ±0.01mm. Sensing and detection unit: including at least a spindle power / torque sensor integrated inside the spindle drive of the drilling machine; the sensor can output the instantaneous spindle power P(t) (unit: kW) and instantaneous torque T(t) (unit: N·m) in real time, with a sampling frequency of 1kHz; Control unit: An industrial-grade programmable automation controller (PAC) is adopted, which embeds the various algorithm modules of this invention. The control unit establishes communication connections with the servo driver of the drive mechanism 3, the drive circuit of the electromagnetic coil array 23, the signal acquisition module of the pressure sensor array 24, and the CNC system of the drilling machine (for acquiring spindle status data) through the EtherCAT real-time industrial Ethernet bus.

[0044] The workflow of this embodiment is as follows: Step 1: Workpiece placement and intelligent conformal clamping The operator places the engine cylinder head on the support mechanism 1 for rough positioning; The control unit applies a first current I1=0.1A to the electromagnetic coil array 23; under this current, the magnetorheological fluid exhibits a low viscosity fluid state, and the flexible pad 22 is soft and has good conformability. The control unit commands the drive mechanism 3 to drive the two intelligent clamps to move toward the workpiece at a low speed and pressure (preset initial thrust 500N) until the flexible pad 22 contacts the workpiece surface. During the contact process, the pressure sensor array 24 collects the pressure values ​​at each point in real time at a period of 1ms. (i=1,2,...,n), and transmit to the control unit; The control unit calculates pressure distribution uniformity indicators in real time, such as the deviation between the pressure at each point and the average pressure. When all All are less than the preset threshold =0.05MPa, and average pressure Achieve the preset initial bonding pressure When the pressure is 0.2 MPa, the uniformity condition is met; this process ensures that the fixture fits perfectly with the side of the cylinder head with its complex curved surface, without the risk of local indentation. The control unit immediately applies a second current I2 = 1.5A to the electromagnetic coil array 23. This current is much greater than the first current, causing the magnetorheological fluid to solidify instantly, with the shear yield stress reaching approximately 40 kPa. The flexible pad 22 changes from a soft state to a rigid support, "locking" the precisely fitted shape. At the same time, based on feedback from the pressure sensor, the control unit precisely adjusts the clamping force to the preset initial processing clamping force F_clamp = 3000N through the torque control mode of the servo drive, and maintains closed-loop control.

[0045] Step 2: Real-time calculation of drilling process and internal stress release rate The control unit sends a "clamping complete" signal to the CNC system of the drilling machine. The CNC system starts the machining program and begins drilling the tappet hole (12mm diameter, 40mm depth) on the cylinder head. During drilling, the spindle power / torque sensor collects instantaneous power data in real time. and feed rate (Provided by the CNC system), sampling period 1ms; The stress relief rate calculation module built into the control unit calculates the cumulative cutting work from the start of drilling to the current time t in real time using the following formula. :

[0046] in, For integration time variable, Instantaneous power The feed rate is used; to improve computational efficiency, discrete summation can be used as an approximation in practical applications. The control unit has a pre-stored calibration model of "cutting work - stress relief rate" obtained from previous process experiments; for the aluminum alloy material in this embodiment, this model can be expressed as an empirical formula:

[0047] in, The total cutting work required to essentially complete stress release of the material at a specific aperture, as determined by experiments (in this example) =200J); will be calculated in real time. Substituting into the formula, we can obtain the current completed internal stress release rate. .

[0048] Step 3: Intelligent release decision after drilling is completed When the drill bit reaches the predetermined depth (40mm), the drilling operation is complete; at this point, the control unit reads the final calculated internal stress release rate. ; The control unit will With the preset first preset threshold =90% for comparison; In this embodiment, the cumulative cutting work is assumed to be at the end of drilling. =195J, calculated to be =97.5%> ; Based on this, the control unit determines that the internal stress of the workpiece has been basically released, and directly loosening it will not cause significant deformation. The control unit performs the release action: When a current I=0A is applied to the electromagnetic coil array 23, the magnetorheological fluid quickly returns to a low-viscosity fluid state, and the clamp loses its rigidity. Command-driven mechanism 3 drives the intelligent gripper back to its initial position; The operator removed the finished cylinder head, and after inspection, the positional error of all holes was less than 0.02mm, which met the design requirements.

[0049] Example 3: Optionally, this embodiment provides an intelligent linkage high-position clamping device for drilling machines. This embodiment focuses on how to use magnetorheological fluid clamps to suppress cutting chatter.

[0050] The device structure in this embodiment is basically the same as that in embodiment 2. The difference is that a chatter suppression algorithm module has been added to the control unit. The workpiece is still an aluminum alloy engine cylinder head, but the processing parameters this time may cause the cutting process to be unstable.

[0051] Specifically: Step 1: Clamping the workpiece Same as step 1 in Example 2, complete the intelligent conformal clamping, and set the clamping force to 3000N; Step 2: Drilling and Active Chatter Suppression The spindle starts and drilling begins; The spindle power / torque sensor acquires instantaneous torque signals in real time. The sampling frequency is 2kHz to meet the requirements of high-frequency analysis. The flutter suppression module of the control unit Perform real-time processing; Using a sliding time window (window length 1024 sampling points) for Perform a Fast Fourier Transform (FFT) to obtain the frequency domain amplitude spectrum of the torque signal. ; Identify the dominant peak frequency in the spectrum (i.e., the frequency of maximum wave energy) and its corresponding amplitude ; Will With the preset flutter threshold (In this embodiment, the torque is set to 1.5 times the root mean square value of normal cutting torque) for comparison; Assuming that during the drilling process, due to fluctuations in cutting parameters or material hardness, the control unit detects... Exceeded And main frequency =800Hz (close to a certain natural frequency of the workpiece-tool system), indicating that chatter is about to occur; The control unit immediately generates a pulsating current signal.

[0052]

[0053] in: This is the DC bias current, used to provide foundation stiffness, and is set to 0.8A. The AC amplitude is used to generate stiffness fluctuations and is set to 0.3A. The modulation frequency is set in this embodiment to be the same as the detected flutter frequency. Same, that is =800Hz; The pulsating current is applied to the electromagnetic coil unit closest to the cutting area (which can be determined by pressure sensors and position information); the pulsating current causes the magnetorheological fluid in this area to undergo a periodic change of "slightly hard to slightly soft" within milliseconds, forming a dynamic damper synchronized with the flutter frequency; this active stiffness modulation effectively disrupts the conditions for flutter to take hold and absorbs vibration energy. The control unit continuously monitors the torque spectrum; after implementing pulsating current, if it detects... amplitude at Descending to The suppression strategy will then be maintained or gradually reduced. Until it is cancelled, in order to avoid excessive intervention; The entire drilling process was completed smoothly without significant chatter, and the surface roughness Ra of the borehole wall decreased from 1.6 μm without suppression to 0.8 μm.

[0054] Step 3: Release After drilling is completed, loosening is performed according to the standard procedure (or in conjunction with the stress release rate judgment in Example 2).

[0055] Example 4: Optionally, this embodiment provides an intelligent linkage high-position clamping device for drilling machines. This embodiment is used to illustrate a stress relief auxiliary program for workpieces with high residual stress (such as titanium alloy bone plates).

[0056] The device structure in this embodiment is basically the same as that in embodiment 2; the workpiece is a medical titanium alloy bone plate with a thickness of 2mm, and multiple micro holes with a diameter of 2mm need to be drilled; the titanium alloy material has high strength and large residual stress, and the workpiece is a thin-walled part, which is extremely easy to deform.

[0057] The specific implementation steps of this embodiment are as follows: Step 1: Clamping the workpiece Same as step 1 in Example 2, complete the intelligent conformal clamping; since the workpiece is small and thin, the initial clamping force is set to 500N.

[0058] Step 2: Real-time calculation of drilling process and internal stress release rate Start the micro-hole drilling program; Real-time acquisition of spindle power and feed rate According to the formula Calculate the cumulative cutting work; For titanium alloys, the "cutting work-stress release rate" model calibrated in the previous experiments is different from that for aluminum alloys. Because titanium alloys release stress slowly, the drilling process itself can only release part of the stress. This embodiment uses a more refined calibration curve. For example, through experimental determination, when drilling a 2mm hole, when the cutting work reaches 5J, the stress release rate is about 60%.

[0059] Step 3: Decision-making after drilling is completed Assuming the drilling of the first hole is complete, the cumulative cutting work is calculated. =5.2J, corresponding to the internal stress release rate =62%; The control unit will With the preset first preset threshold =80% for comparison; in this example < This triggers the stress relief auxiliary program.

[0060] Step 4: Stress Relief Assistance Procedure Clamping force adjustment: The control unit commands the drive mechanism 3 to reduce the clamping force to the second preset value. =300N (60% of the original clamping force); at the same time, a very small current (such as 0.05A) is applied to the electromagnetic coil array 23 to make the magnetorheological fluid enter the micro-yield mode; in this mode, the magnetorheological fluid exhibits weak solid properties, allowing the workpiece to slip or deform at the micrometer level when subjected to force, but still providing basic positioning constraints. Spindle micro-feed: The control unit sends a command to the CNC system, requesting the spindle (now replaced with a tool holder without a drill or with a polishing head) to perform the following actions: The spindle operates at extremely low speeds. =20 rpm rotation; With extremely low feed rate =0.005mm / r, feed again towards the bottom of the machined hole; Stress induction and monitoring: When the end of the tool holder (or the tiny cutting edge of the polishing head) contacts the vicinity of the bottom of the hole, the hole wall or bottom will undergo a slight deformation due to the residual stress inside the workpiece; this deformation will generate a weak reaction force on the tool, which is reflected in the slight fluctuation of the spindle power; the spindle power / torque sensor continuously collects the power signal in a high-sensitivity mode. Power monitoring and judgment: The control unit monitors the instantaneous power during the micro-feed process in real time. Define a third preset threshold that is close to zero. =2W (this value is much smaller than the normal drilling power); During the first micro-feed, the sensor detected... A fluctuation of approximately 8-10W indicates that stress release has occurred; The control unit instructs the spindle to retract outside the hole, and then performs a micro-feed again; During the second feed, the detected Fluctuations decreased to 3-4 W; On the third feed, consistently below =2W, and there is no significant fluctuation; Stress relief completion determination: During two consecutive micro-feed processes All below The control unit determines that the residual stress around the hole has been basically released and the workpiece has reached a new stable state.

[0061] Step 5: Release The control unit performs the release action: When the electromagnetic coil array 23 is de-energized, the magnetorheological fluid liquefies. Command to drive mechanism 3 to retract; Repeat steps 2-5 above for all holes to be machined; The titanium alloy bone plate processed and loosened under this procedure was tested by a coordinate measuring machine. All micropore position errors were <0.01mm, and the overall flatness variation of the plate was <0.01mm, which fully meets the standards for medical implants.

[0062] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A smart linkage high-position clamping device for a drilling machine, characterized in that: include: The supporting mechanism (1) is used to place the workpiece; A clamping mechanism (2) is provided on the bearing mechanism (1) and is used to apply a clamping force to the workpiece; The driving mechanism (3) is connected to the clamping mechanism (2) and is used to drive the clamping mechanism (2) to perform clamping or releasing actions; The sensing and detection unit includes at least a spindle power / torque sensor for acquiring cutting energy consumption data of the drilling spindle during the machining process; The control unit is communicatively connected to the drive mechanism (3), the sensing and detection unit, and the spindle control system of the drilling machine, respectively. The control unit is configured as follows: Receives cutting energy consumption data in real time from the spindle power / torque sensor; Based on the cutting energy consumption data, calculate the internal stress release rate that has been completed in the current machining process; The timing for releasing the clamping mechanism (2) is determined based on the internal stress release rate.

2. The intelligent linkage high-position clamping device for a drilling machine according to claim 1, characterized in that: The clamping mechanism (2) includes an intelligent clamp that contacts the workpiece. The intelligent clamp includes a rigid back plate (21) and a flexible pad (22) disposed on the side of the rigid back plate (21) facing the workpiece. The flexible pad (22) is filled with magnetorheological fluid and has an embedded electromagnetic coil array (23). The control unit is connected to the electromagnetic coil array (23) and configured to change the apparent viscosity of the magnetorheological fluid by adjusting the current of the electromagnetic coil array (23) to adjust the stiffness of the contact surface between the smart fixture and the workpiece.

3. The intelligent linkage high-position clamping device for a drilling machine according to claim 2, characterized in that: The flexible pad (22) is also embedded with a pressure sensor array (24), which is connected to the control unit and is used to monitor the pressure distribution of the contact surface between the smart fixture and the workpiece in real time.

4. The intelligent linkage high-position clamping device for a drilling machine according to claim 2 or 3, characterized in that: The control unit is also configured to: When the clamping mechanism (2) performs the clamping action, a first current is applied to the electromagnetic coil array (23) to make the magnetorheological fluid in a low viscosity state; Based on the feedback from the pressure sensor array (24), the drive mechanism (3) is controlled to drive the intelligent fixture to fit the workpiece until the detection value of the pressure sensor array (24) reaches the preset uniformity condition. In response to the uniformity condition being met, a second current is applied to the electromagnetic coil array (23) to solidify the magnetorheological fluid, the second current being greater than the first current.

5. A smart linkage high-position clamping device for a drilling machine according to claim 2 or 3, characterized in that: The control unit is also configured to: During the drilling process of the drilling machine spindle, the instantaneous torque data fed back by the spindle power / torque sensor is received in real time; Extract the fluctuation characteristics of the instantaneous torque data; When the amplitude of the wave characteristic exceeds a preset threshold, a pulsating current associated with the frequency of the wave characteristic is applied to the electromagnetic coil array (23).

6. The intelligent linkage high-position clamping device for a drilling machine according to claim 1, characterized in that: The control unit is configured to calculate the internal stress release rate based on the cutting energy consumption data, specifically including: Calculate the integral value of cutting work based on the cutting energy consumption data; The integral value of the cutting work is compared with the preset stress relief model to obtain the internal stress relief rate of the current machining completed.

7. The intelligent linkage high-position clamping device for a drilling machine according to claim 6, characterized in that: The control unit is configured to determine the timing of the release of the clamping mechanism (2) based on the internal stress release rate, specifically including: The internal stress release rate is compared with a first preset threshold. If the internal stress release rate reaches or exceeds the first preset threshold, the drive mechanism (3) is controlled to perform a release action.

8. The intelligent linkage high-position clamping device for a drilling machine according to claim 7, characterized in that: The control unit is also configured to: If the internal stress release rate is lower than the first preset threshold, the stress release auxiliary program is triggered. The stress relief assistance procedure includes: Control the drive mechanism (3) to adjust the clamping force of the clamping mechanism (2) to a second preset value; Control the drilling machine spindle to perform at least one idle stroke or a small cutting stroke on the machined hole with preset low-speed feed parameters; During this period, data from the spindle power / torque sensor continues to be received until stress release is determined to be complete.

9. The intelligent linkage high-position clamping device for a drilling machine according to claim 8, characterized in that: The control unit determines that stress release is complete when the cutting power detected by the spindle power / torque sensor drops below a third preset threshold during the idle or micro-cutting stroke.

10. The intelligent linkage high-position clamping device for a drilling machine according to claim 2, characterized in that: The electromagnetic coil array (23) consists of multiple independently controllable coil units, which are arranged in an array within the flexible pad (22).

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