Ball cage type constant velocity universal joint machining drilling method based on adaptive cooling control

Abstract

The application discloses a ball cage type constant velocity universal joint machining drilling method based on adaptive cooling control and relates to the field of machining drilling, which comprises the following steps: clamping the ball cage type constant velocity universal joint and aligning the workpiece, calling initial parameters based on material and hole characteristics, and starting a cooling system; collecting machining state signals in real time during drilling, dynamically adjusting the feed speed, the spindle speed and the flow and pressure of the cooling liquid, and realizing collaborative control of machining and cooling; after reaching the hole depth, the spindle is paused for cleaning in the rotating state, and then the rotation and cooling are stopped and the tool is withdrawn; the key signals, adjustment instructions, parameters and final hole quality data of the whole process are all associated and saved, forming a complete machining history record. The application has the advantages that the drilling parameters and the cooling strategy are dynamically and collaboratively adjusted, the drilling precision and machining stability of the ball cage type constant velocity universal joint are improved, the tool life is prolonged, and machining data traceability is realized.

Description

Technical Field

[0001] This invention relates to the field of drilling, and in particular to a drilling method for ball cage constant velocity universal joints based on adaptive cooling control. Background Technology

[0002] With the increasing demands on the performance of key components in the high-end equipment manufacturing industry, the ball-cage constant velocity joint, as a core component of the transmission system, directly determines the service life of the overall equipment through its machining accuracy and reliability. Traditional drilling processes, when dealing with high-hardness alloy materials, often suffer from problems such as accelerated tool wear, hole diameter deviations, deterioration of hole wall surface integrity, and microcrack initiation due to localized high temperatures in the drilling zone. These issues severely affect the fatigue strength and transmission accuracy of the ball-cage constant velocity joint.

[0003] Most current drilling methods for ball cage constant velocity joints employ fixed cooling and machining parameters, failing to dynamically adjust based on real-time changes in drilling axial force, local temperature, vibration, and other status signals during the drilling process. This lack of coordination between cooling strategies and drilling actions easily leads to problems such as insufficient cooling, poor chip removal, or deformation of the ball cage constant velocity joint due to overcooling. This negatively impacts drilling accuracy and surface quality, and also accelerates tool wear and shortens tool life. Furthermore, some methods lack sufficient clamping and positioning accuracy, making it difficult to ensure precise alignment between the drilling axis and the machine tool spindle axis, easily resulting in hole position deviations. The absence of comprehensive real-time signal monitoring and graded adjustment mechanisms also hinders timely intervention when machining anomalies occur, requiring manual machine stoppage for inspection and reducing machining efficiency. In addition, most methods do not link and save data throughout the entire machining process, making traceability impossible and hindering subsequent process optimization and quality problem investigation, thus failing to meet the high-precision and high-efficiency machining requirements of ball cage constant velocity joints. Summary of the Invention

[0004] To improve existing methods, a drilling method for ball cage constant velocity joints based on adaptive cooling control is provided. This method dynamically and collaboratively adjusts drilling parameters and cooling strategies by acquiring machining status signals in real time, effectively improving the drilling accuracy and machining stability of ball cage constant velocity joints and extending tool life.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A drilling method for ball-cage constant velocity universal joints based on adaptive cooling control includes:

[0007] The ball cage constant velocity universal joint to be processed is clamped in the fixture of a multi-axis CNC machine tool. Multiple pressures are applied from the non-processing area of ​​the ball cage constant velocity universal joint through an adjustable clamping mechanism to initially align the axis of the hole to be drilled with the axis of the machine tool spindle.

[0008] Based on the material grade of the ball cage constant velocity universal joint and the design diameter and depth of the hole to be drilled, the preset initial machining parameter set is called in the CNC system, and the cooling system is started to pre-spray coolant with initial flow rate and pressure.

[0009] The spindle is started to rotate and the drill bit is driven to feed towards the workpiece at an initial axial feed speed to begin drilling. Real-time signals of the machining status are collected, and the parameters of the CNC system are dynamically adjusted based on the collected signals to generate control commands. Based on the control commands, the drilling action and cooling strategy are coordinated and adjusted.

[0010] Under drilling and cooling control, the drill bit continues to feed until the preset hole depth is reached. The spindle pauses axial feed while rotating and maintains the current coolant spray state for a preset cleaning time. The spindle is then controlled to stop rotating, the coolant spray stops, and the retraction operation is performed to completely remove the drill bit from the workpiece.

[0011] The real-time signal data recorded during the drilling process, the trigger point of the adjustment command, the adjusted parameters, and the final hole quality data are associated and saved to form a processing history record.

[0012] Preferably, the acquisition of real-time processing status signals specifically includes:

[0013] The physical state signals during the drilling process are collected in real time by sensors integrated on the spindle or fixture.

[0014] Dynamic axial force signals during drilling are acquired by sampling intervals using a high-response-frequency piezoelectric force measuring washer or a spindle servo motor current sensor.

[0015] Local temperature signals are obtained by temperature sensors placed close to the drill bit clamping area or the workpiece machining area.

[0016] Vibration acceleration signals of the spindle or workpiece fixture are collected during the drilling process using vibration sensors.

[0017] Preferably, the dynamic adjustment of CNC system parameters based on the acquired signals specifically includes:

[0018] The real-time acquired drilling axial force signal and local temperature signal are input to the adaptive control module of the CNC system. The adaptive control module has preset axial force safety threshold range and temperature safety threshold range related to material and hole diameter.

[0019] The real-time signal is compared with the safety threshold range to calculate the percentage margin of the real-time axial force, temperature and vibration signals relative to the current dynamic threshold, and the slope of change within a short time window is calculated.

[0020] When the drilling axial force or local temperature is in the lower range of the safety threshold and the rate of change is within the safety threshold, the machining state is determined to be stable, and the current feed rate and cooling parameters are maintained.

[0021] When the drilling axial force signal shows a continuous upward trend and approaches the upper limit of the safety threshold range, or when the local temperature signal shows a continuous upward trend and approaches the upper limit of the safety threshold range, it is determined that the machining load is increasing or the heat dissipation demand is increasing, and a first type of adjustment command is generated.

[0022] When the drilling axial force signal instantaneously exceeds the upper limit of the safety threshold range or the local temperature signal instantaneously exceeds the upper limit of the safety threshold range, it is determined that there is poor chip removal, slight tool wear, or insufficient cooling, and a second type of adjustment command is generated.

[0023] Preferably, the calculation of the percentage margin of real-time axial force, temperature, and vibration signals relative to the current dynamic threshold, and the calculation of the slope of change within a short time window specifically include:

[0024] For each signal, calculate the numerical difference between the current signal value and the upper limit of the warning threshold, and calculate the ratio of the difference to the reference range, where the reference range is the span between the upper limit of the warning threshold and the preset lower limit;

[0025] Converting the ratio to a percentage form gives the percentage margin.

[0026] Set a fixed, short historical time window for each signal, and extract a series of values ​​for the signal arranged in chronological order within that time window;

[0027] The trend of signal change within a time window is determined by fitting a line using the least squares method, and the steepness of the trend is quantified by calculating the equivalent value of the slope of the fitted line.

[0028] Preferably, the coordinated adjustment of drilling actions and cooling strategies based on control commands specifically includes:

[0029] Based on the adjustment instructions generated by the adaptive control module, the drilling action and cooling strategy are dynamically adjusted.

[0030] If a first-class adjustment command is generated, the first-level adjustment is executed. While maintaining the spindle speed unchanged or making minor adjustments, the axial feed rate is reduced by a preset amount to reduce the instantaneous drilling load. The cooling system is controlled to increase the coolant injection pressure by a preset level and increase the coolant flow rate to enhance the cooling effect of the coolant on the drill bit cutting edge and the workpiece hole wall, as well as the ability to flush and remove chips.

[0031] If a second type of adjustment command is generated, the second level of adjustment is executed. Based on the first level of adjustment, the axial feed rate is reduced to a lower maintenance feed rate, and the spindle is controlled to maintain rotation while performing a small axial retraction action. The retraction distance allows the main cutting edge of the drill bit to completely exit the drilled section and feed back to the original depth.

[0032] During the second stage of adjustment, the cooling system switches to a high-pressure, high-flow-rate flushing mode to continuously flush the drill bit tip and chip flue, removing clogged chips or improving cooling and lubrication conditions.

[0033] After the adjustment is implemented, continue to monitor the drilling axial force and local temperature signals;

[0034] If the signal falls back to a stable range within the safe threshold, the feed rate will be gradually restored to the level before the adjustment. If the signal still does not improve effectively, an alarm will be triggered, prompting manual intervention to check the tool or process.

[0035] Preferably, the first-level adjustment specifically includes:

[0036] The feed rate is proportionally adjusted based on the degree to which the signal exceeds the ideal operating range and the slope of its change.

[0037] The coolant is adjusted based on a pressure-priority and flow-following strategy to increase the injection pressure. Based on the increased pressure, the flow rate is increased in steps according to the feedback of the temperature signal. During this stage, the spindle speed remains stable.

[0038] Preferably, the second-level adjustment specifically includes:

[0039] The retraction speed of a small axial retraction motion is higher than the machining feed rate. After the main cutting edge has completely exited the hole or the drilled section, maintain a pause of 0.1 seconds.

[0040] During the pause, the high-pressure, high-flow-rate flushing mode is activated, and the coolant jet is guided to the root of the drill bit's spiral groove for forced reverse and forward flushing.

[0041] After flushing, the drill bit is re-fed at a maintenance feed rate, which is lower than the normal feed rate;

[0042] If the monitoring signal returns to normal after this intervention cycle is executed once, it is determined that the blockage or abnormality has been resolved, and the parameters are gradually restored to those before the intervention.

[0043] Preferably, in the dynamic adjustment of CNC system parameters based on the acquired signals, the vibration acceleration signal is used as an additional criterion: when the vibration intensity continuously or instantaneously exceeds its safety threshold, regardless of the axial force and temperature signals, an adjustment command containing deceleration and enhanced cooling commands is generated.

[0044] Compared with the prior art, the advantages of the present invention are:

[0045] This system achieves precise, intelligent, and efficient collaborative machining processes. Through multi-point adjustable clamping, it ensures precise alignment of the drilling axis and spindle axis, laying the foundation for machining accuracy. Combined with preset initial processes for the ball-cage constant velocity joint material and drilling parameters, and real-time signal acquisition and dynamic parameter adjustment, it can progressively control feed rate, spindle status, and cooling strategy based on signals such as drilling axial force, local temperature, and vibration acceleration. This effectively avoids problems such as poor chip removal, tool wear, and insufficient cooling, reducing machining defect rates. Simultaneously, the cooling system is coordinated with the drilling action, progressively adjusting coolant pressure and flow rate to balance cooling, lubrication, and chip removal effects, extending tool life and improving machining stability. Furthermore, all machining process data is linked and saved, forming a traceable machining history, facilitating process optimization and quality traceability. Overall, it improves the machining accuracy, efficiency, and consistency of ball-cage constant velocity joint drilling, adapting to the high-efficiency machining needs of various ball-cage constant velocity joint specifications. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the drilling method for ball cage type constant velocity universal joint based on adaptive cooling control proposed in this invention. Detailed Implementation

[0047] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0048] See Figure 1 As shown, the drilling method for ball cage constant velocity universal joints based on adaptive cooling control includes:

[0049] S1: The ball cage constant velocity universal joint to be processed is clamped in the fixture of the multi-axis CNC machine tool. Multiple pressures are applied from the non-processing area of ​​the ball cage constant velocity universal joint through the adjustable clamping mechanism to make the axis of the hole to be drilled initially aligned with the axis of the machine tool spindle.

[0050] S2: Based on the material grade of the ball cage constant velocity universal joint and the design diameter and depth of the hole to be drilled, the preset initial machining parameter set is called in the CNC system, and the cooling system is started to pre-spray coolant with initial flow rate and pressure.

[0051] S3: Start the spindle rotation and drive the drill bit to feed towards the workpiece at the initial axial feed speed to start drilling. Real-time signals of the processing status are collected, and the parameters of the CNC system are dynamically adjusted based on the collected signals to generate control commands. Based on the control commands, the drilling action and cooling strategy are coordinated and adjusted.

[0052] S4: Under drilling and cooling control, the drill bit continues to feed until the preset hole depth is reached. The spindle pauses axial feed while rotating and maintains the current coolant spray state for a preset cleaning time. The spindle is then controlled to stop rotating, the coolant spray stops, and the retraction operation is performed to completely remove the drill bit from the workpiece.

[0053] S5: Save the real-time signal data recorded during the drilling process, the adjustment command trigger point, the adjusted parameters, and the final hole quality data together to form a processing history record.

[0054] In step S1, the ball-cage constant velocity joint to be machined is clamped in the fixture of a multi-axis CNC machine tool. The main body of the fixture has a V-shaped locating block and an axial locating end face. The operator manually inserts and fits the outer cylindrical surface of one of the forks of the ball-cage constant velocity joint into the V-groove of the V-shaped locating block, while simultaneously pushing a designated side of the fork against the axial locating end face, so that it obtains a defined and repeatable initial posture in the fixture. After the ball-cage constant velocity joint has completed the reference fit, the operator operates the adjustable clamping mechanism to finally fix the ball-cage constant velocity joint. After completing the above positioning and clamping, a standard tool setter is installed into the machine tool spindle. Through CNC program control, the machine tool spindle is moved sequentially to two measuring planes perpendicular to the theoretical position of the axis of the hole to be drilled. The tool setter is used to touch the two measuring planes at low speed, and the spindle center coordinates at each touch are recorded. Based on these two coordinate values, the spatial deviation angle and translation distance between the current spindle axis and the theoretical drilling axis are calculated. By fine-tuning the circumferential angle of the ball-cage constant velocity universal joint on the fixture, the theoretical drilling axis is virtually aligned with the machine tool spindle axis.

[0055] In S2, a material-tool-process parameter database is pre-established and stored in the CNC system. When the operator inputs or selects the material grade, drill type and diameter, and target hole depth of the ball cage constant velocity universal joint to be machined, the system initiates parameter retrieval logic. First, it matches the material group based on the material grade to determine the basic cutting characteristics of the material. Combined with the drill diameter, the recommended initial cutting speed is calculated using an embedded data table. The calculation formula is:

[0056]

[0057] in, The initial cutting linear velocity, These are benchmark coefficients determined based on the company's processing experience or data recommended by tool suppliers. This function reflects the ease or difficulty of processing a material. Generally, the higher the hardness and toughness of the material, the lower the function's output value. A function reflecting the properties of the tool material and coating; high-performance tools allow for higher linear speeds.

[0058] Based on the initial cutting line speed Given the drill bit diameter D, calculate the initial spindle speed:

[0059]

[0060] The initial feed per revolution, f_n_initial, is determined based on the drill diameter, hole depth, and material properties, aiming to balance cutting efficiency and chip removal capability. All calculated parameters, along with the coolant type, initial injection pressure, and initial flow rate selected based on the material's thermal properties, together constitute the initial machining parameter set for the current task, which is loaded into the CNC's current machining program variables.

[0061] The cooling system first activates the coolant thermostat unit to ensure the supplied coolant temperature remains stable within the preset range. Then, the main coolant pump starts, and the coolant, after passing through a filter, is pumped to the rotary distributor inside the spindle. The high-pressure coolant flows through channels in the spindle and tool holder, directly to the channel in the drill chuck or hydraulic tool holder that connects to the drill shank tail, and finally is delivered to the cutting area through coolant holes inside the drill bit or along the drill bit's spiral grooves.

[0062] During the initial positioning phase of the drilling cycle, when the spindle carrying the drill bit moves to a short, safe distance from the workpiece surface, the CNC executes a coolant pre-spray subroutine. The cooling system controller receives the instruction and opens the coolant valve according to the initial pressure and flow rate set in the initial machining parameter set, allowing coolant to spray from the drill tip. This pre-spray process lasts for several seconds, filling and establishing a stable coolant pressure and flow path, expelling air from the pipes; pre-wetting and cooling the workpiece surface to be machined and the drill cutting edge to reduce thermal shock during initial entry; and verifying the coolant supply. If the pressure or flow sensor does not detect the set value, the system will alarm and pause machining to prevent dry drilling.

[0063] In S3, the raw signals, temperature, and vibration data acquired in real time are filtered and denoised. The adaptive control module then retrieves the corresponding safety threshold range from a pre-stored dynamic threshold model based on the current machining stage and estimated tool wear condition. The safety threshold range is not a fixed value but a dynamically adjusted interval as the machining process progresses. Similarly, temperature and vibration thresholds are pre-set based on material properties, bore diameter, tool type, and historical successful machining data, and can be optimized during the learning process.

[0064] The system calculates the percentage margin of the current signal value relative to its dynamic safety threshold upper limit to quantify the safety space between the current state and the warning boundary. Taking axial force as an example, the percentage margin calculation formula is as follows:

[0065]

[0066] in, As a percentage margin, This is the measured value of the axial force at the current moment. This represents the nominal axial force at the current depth, typically taken as the midpoint of the axial force threshold range or a value calculated based on a theoretical model. This represents the upper limit of the axial force threshold under the current depth and tool condition.

[0067] when When the value is approximately 100%, it indicates that the current axial force is close to the ideal nominal value, with sufficient margin.

[0068] when When the value reaches 0%, it indicates that the current axial force is close to the upper limit of the threshold and the margin is about to be exhausted.

[0069] when When the value is less than 0, it indicates that the current axial force has exceeded the upper limit of the threshold.

[0070] The percentage margins for temperature and vibration are calculated similarly, using their respective current values, nominal values, and upper threshold limits.

[0071] The system takes a sequence of signal data within a fixed short time window as its object and calculates its changing trend. Taking the axial force signal as an example, it uses linear regression to calculate its slope. The system performs force-time data pairing within the window... Perform first-order linear fitting , The slope represents the average rate of change of axial force within that time window.

[0072] When the value is greater than 0, the axial force tends to increase.

[0073] When ≈0, the axial force remains stable.

[0074] When the value is less than 0, the axial force shows a decreasing trend.

[0075] The slopes of temperature and vibration changes are calculated in the same way.

[0076] The adaptive control module integrates two dimensions: percentage margin and slope of change, and takes into account the correlation between signals, and generates adjustment instructions according to preset logic.

[0077] Criterion 1: State stability condition: The percentage margin of all key signals is greater than the stability threshold, and the absolute value of their change slopes is less than the stability slope threshold. The processing state is determined to be stable, no adjustment command is generated, and all current processing parameters are maintained.

[0078] Criterion 2: Conditions for generating a first-class adjustment instruction: satisfying any one or all of the following conditions:

[0079] The percentage margin of any key signal is below the warning threshold and its change slope is greater than 0.

[0080] Although the percentage margin of any key signal is still higher than the warning threshold, its change slope remains positive and is greater than the positive slope warning threshold, indicating a risk of rapid deterioration.

[0081] If it is determined that the machining load is increasing or the heat dissipation demand is increasing, a first-type adjustment command is generated. This command typically includes: slightly reducing the feed rate by a preset step size, while increasing the coolant pressure.

[0082] Criterion 3: Condition for generating a second type of adjustment instruction: satisfying any of the following conditions:

[0083] The instantaneous value of any key signal exceeds its dynamic threshold limit.

[0084] The percentage margin of the vibration signal drops sharply, accompanied by a sudden change in the axial force signal.

[0085] If a momentary anomaly is detected, a second type of adjustment instruction is generated. This instruction includes stronger intervention measures: immediately reduce the feed rate to the minimum maintenance rate, execute a rapid retraction-refeed cycle to attempt chip breaking and unblocking, switch the coolant to the highest pressure, high flow rate flushing mode, and may trigger an audible and visual alarm to alert the operator.

[0086] Once the adaptive control module of the CNC system generates an adjustment command, the command is presented as a structured data packet containing the command type, adjustment target, and recommended range.

[0087] The first level of adjustment aims to bring the processing state back to the ideal working range through small, precise parameter corrections. The core of this adjustment is proportional control and pressure priority followed by flow rate.

[0088] The feed rate reduction is dynamically calculated based on the percentage margin and change slope of the fundamental signal that triggers the adjustment. A baseline reduction ratio is set, and the actual reduction ratio is calculated using the following formula:

[0089]

[0090] in, This represents the percentage reduction in the actual feed rate for the current cycle, where M is the current percentage margin of the primary signal that triggered the adjustment. To generate the margin warning threshold for the first type of adjustment instruction, |k| is the absolute value of the short-time change slope of the main signal that triggers the adjustment. The maximum allowable slope reference value is preset, and α and β are weighting coefficients. α+β=1 is used to balance the effects of insufficient margin and trend deterioration.

[0091] Upon receiving the instruction, the cooling system controller first increases the coolant injection pressure by a preset level. The pressure increase is related to the feed rate reduction ratio:

[0092]

[0093] in, The adjusted target injection pressure, For the current initial or previous cycle pressure, As the pressure-feed correlation coefficient, prioritizing pressure increases aims to instantly enhance the coolant's penetration and lubrication film strength, breaking any potential accumulation of cutting heat.

[0094] After the pressure stabilizes, the system monitors the temperature signal and its rate of change. If the rate of change does not turn negative within the timeframe after the pressure increase, a step-by-step increase in flow rate is initiated. The flow rate is increased in stages, with a monitoring window observed after each step. If the temperature trend is contained, the increase stops; otherwise, the next step is performed until the system's maximum allowable flow rate is reached or the temperature trend reverses. During this stage, the spindle speed remains constant in principle to avoid introducing additional cutting heat and vibration disturbances. Only symbolic fine-tuning is performed in extreme cases.

[0095] The second level of adjustment aims to address the transient anomaly that has occurred, with the core being tool retraction for unblocking and vigorous flushing. The feed rate is reduced to a maintenance feed rate, typically set to 10%-20% of the normal feed rate. Subsequently, the CNC executes a retraction-pause-refeed cycle: controlling the Z-axis to reverse for rapid tool retraction. The retraction distance must ensure that the drill bit's main cutting edge completely exits the drilled section; the calculation formula is as follows:

[0096]

[0097] in, This is the distance the blade retracts. Let be the axial projection length of the drill bit chip flute. Additional distance for safety.

[0098] After the cutter is fully retracted, the spindle continues to rotate, pausing the feed motion for a very short pause. Within this window, the cooling system immediately switches to high-pressure, high-flow-rate flushing mode: the jet pressure jumps to the system's maximum allowable operating pressure, and the flow rate simultaneously jumps to its maximum. Through an adjustable nozzle or by utilizing the centrifugal force of the rotating drill bit, the jet is precisely guided to the root of the drill bit's helical grooves, providing forced forward and reverse flushing. After the flushing pause, the spindle continues to rotate, and the Z-axis refeeds to the hole depth position before the cutter retraction at a maintenance feed rate.

[0099] After completing one intervention cycle and resuming feed, the system closely monitors the axial force and temperature signals within the time window. If the percentage margin of the signal recovers to a safe value and the rate of change approaches zero, the blockage or abnormality is considered resolved. Upon successful resolution, the system gradually restores the machining parameters, progressively increasing the feed rate back to its original or new optimized value in 10% increments, while simultaneously adjusting the coolant pressure and flow rate back to normal levels in a corresponding stepwise manner. If the signal does not improve or continues to deteriorate after one intervention cycle, the system can automatically repeat the intervention cycle. If the second cycle is still ineffective, a high-level alarm is immediately triggered, and machining is stopped.

[0100] In S4, the CNC system monitors the Z-axis position coordinates of the drill bit tip in real time with precision using a high-resolution linear encoder or servo motor encoder. When the absolute value of the difference between the Z-axis position coordinates and the target hole depth coordinates set in the program is less than or equal to the depth set by the system and reaches the tolerance, a command is immediately sent to the feed axis servo drive to stop further axial feed movement. At this time, the spindle continues to rotate at the current speed, and the coolant continues to be sprayed at the currently adjusted pressure and flow rate.

[0101] After the feed is paused, the timed process of the bottom hole cleaning cycle is initiated. Throughout the cleaning cycle, the spindle maintains its rotational speed. The cooling system maintains continuous pressure and flow, with coolant continuously sprayed from the drill bit to perform high-pressure flushing on the bottom hole and hole wall, thoroughly flushing out the fine chips that have accumulated due to the feed stoppage.

[0102] After the cleaning timer expires, the system performs a sequential stop operation, sending a shutdown command to the cooling system controller. The coolant pump reduces its output, the valve closes, and the injection pressure and flow rate drop to zero within a short time. Once it is confirmed that the coolant has begun to shut off, a deceleration stop command is immediately sent to the spindle drive. The spindle speed smoothly decreases to zero from a preset deceleration rate.

[0103] After confirming that the spindle has completely stopped rotating, the CNC controls the feed axis to perform a tool retraction operation. A relatively fast retraction speed is used, generally much higher than the final machining feed rate, and the system controls the drill bit to move linearly in the opposite direction along the drilling axis. The drill bit continues to retract until it reaches a safe height completely away from the workpiece and fixture. Once the drill tip reaches this safe height, the entire drilling cycle is complete.

[0104] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0105] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A drilling method for ball-cage type constant velocity universal joints based on adaptive cooling control, characterized in that, include: The ball cage constant velocity universal joint to be processed is clamped in the fixture of a multi-axis CNC machine tool. Multiple pressures are applied from the non-processing area of ​​the ball cage constant velocity universal joint through an adjustable clamping mechanism to initially align the axis of the hole to be drilled with the axis of the machine tool spindle. Based on the material grade of the ball cage constant velocity universal joint and the design diameter and depth of the hole to be drilled, the preset initial machining parameter set is called in the CNC system, and the cooling system is started to pre-spray coolant with initial flow rate and pressure. The spindle is started to rotate and the drill bit is driven to feed towards the workpiece at an initial axial feed speed to begin drilling. Real-time signals of the machining status are collected, and the parameters of the CNC system are dynamically adjusted based on the collected signals to generate control commands. Based on the control commands, the drilling action and cooling strategy are coordinated and adjusted. Under drilling and cooling control, the drill bit continues to feed until the preset hole depth is reached. The spindle pauses axial feed while rotating and maintains the current coolant spray state for a preset cleaning time. The spindle is then controlled to stop rotating, the coolant spray stops, and the retraction operation is performed to completely remove the drill bit from the workpiece. The real-time signal data recorded during the drilling process, the trigger point of the adjustment command, the adjusted parameters, and the final hole quality data are associated and saved to form a processing history record.

2. The drilling method for ball-cage type constant velocity universal joint based on adaptive cooling control according to claim 1, characterized in that, The acquisition of real-time processing status signals specifically includes: The physical state signals during the drilling process are collected in real time by sensors integrated on the spindle or fixture. Dynamic axial force signals during drilling are acquired by sampling intervals using a high-response-frequency piezoelectric force measuring washer or a spindle servo motor current sensor. Local temperature signals are obtained by temperature sensors placed close to the drill bit clamping area or the workpiece machining area. Vibration acceleration signals of the spindle or workpiece fixture are collected during the drilling process using vibration sensors.

3. The drilling method for ball cage type constant velocity universal joint based on adaptive cooling control according to claim 1, characterized in that, The dynamic adjustment of CNC system parameters based on the acquired signals specifically includes: The real-time acquired drilling axial force signal and local temperature signal are input to the adaptive control module of the CNC system. The adaptive control module has preset axial force safety threshold range and temperature safety threshold range related to material and hole diameter. The real-time signal is compared with the safety threshold range to calculate the percentage margin of the real-time axial force, temperature and vibration signals relative to the current dynamic threshold, and the slope of change within a short time window is calculated. When the drilling axial force or local temperature is in the lower range of the safety threshold and the rate of change is within the safety threshold, the machining state is determined to be stable, and the current feed rate and cooling parameters are maintained. When the drilling axial force signal shows a continuous upward trend and approaches the upper limit of the safety threshold range, or when the local temperature signal shows a continuous upward trend and approaches the upper limit of the safety threshold range, it is determined that the machining load is increasing or the heat dissipation demand is increasing, and a first type of adjustment command is generated. When the drilling axial force signal instantaneously exceeds the upper limit of the safety threshold range or the local temperature signal instantaneously exceeds the upper limit of the safety threshold range, it is determined that there is poor chip removal, slight tool wear, or insufficient cooling, and a second type of adjustment command is generated.

4. The drilling method for ball cage type constant velocity universal joint based on adaptive cooling control according to claim 3, characterized in that, The calculation of the percentage margin of real-time axial force, temperature, and vibration signals relative to the current dynamic threshold, and the calculation of the slope of change within a short time window specifically include: For each signal, calculate the numerical difference between the current signal value and the upper limit of the warning threshold, and calculate the ratio of the difference to the reference range, where the reference range is the span between the upper limit of the warning threshold and the preset lower limit; Converting the ratio to a percentage form gives the percentage margin. Set a fixed, short historical time window for each signal, and extract a series of values ​​for the signal arranged in chronological order within that time window; The trend of signal change within a time window is determined by fitting a line using the least squares method, and the steepness of the trend is quantified by calculating the equivalent value of the slope of the fitted line.

5. The drilling method for ball cage type constant velocity universal joint based on adaptive cooling control according to claim 1, characterized in that, The coordinated adjustment of drilling actions and cooling strategies based on control commands specifically includes: Based on the adjustment instructions generated by the adaptive control module, the drilling action and cooling strategy are dynamically adjusted. If a first-class adjustment command is generated, the first-level adjustment is executed. While maintaining the spindle speed unchanged or making minor adjustments, the axial feed rate is reduced by a preset amount to reduce the instantaneous drilling load. The cooling system is controlled to increase the coolant injection pressure by a preset level and increase the coolant flow rate to enhance the cooling effect of the coolant on the drill bit cutting edge and the workpiece hole wall, as well as the ability to flush and remove chips. If a second type of adjustment command is generated, the second level of adjustment is executed. Based on the first level of adjustment, the axial feed rate is reduced to a lower maintenance feed rate, and the spindle is controlled to maintain rotation while performing a small axial retraction action. The retraction distance allows the main cutting edge of the drill bit to completely exit the drilled section and feed back to the original depth. During the second stage of adjustment, the cooling system switches to a high-pressure, high-flow-rate flushing mode to continuously flush the drill bit tip and chip flue, removing clogged chips or improving cooling and lubrication conditions. After the adjustment is implemented, continue to monitor the drilling axial force and local temperature signals; If the signal falls back to a stable range within the safe threshold, the feed rate will be gradually restored to the level before the adjustment. If the signal still does not improve effectively, an alarm will be triggered, prompting manual intervention to check the tool or process.

6. The drilling method for ball-cage type constant velocity universal joints based on adaptive cooling control according to claim 5, characterized in that, The first level of adjustment specifically includes: The feed rate is proportionally adjusted based on the degree to which the signal exceeds the ideal operating range and the slope of its change. The coolant is adjusted based on a pressure-priority and flow-following strategy to increase the injection pressure. Based on the increased pressure, the flow rate is increased in steps according to the feedback of the temperature signal. During this stage, the spindle speed remains stable.

7. The drilling method for ball-cage type constant velocity universal joints based on adaptive cooling control according to claim 5, characterized in that, The second level of adjustment specifically includes: The retraction speed of a small axial retraction motion is higher than the machining feed rate. After the main cutting edge has completely exited the hole or the drilled section, maintain a pause of 0.1 seconds. During the pause, the high-pressure, high-flow-rate flushing mode is activated, and the coolant jet is guided to the root of the drill bit's spiral groove for forced reverse and forward flushing. After flushing, the drill bit is re-fed at a maintenance feed rate, which is lower than the normal feed rate; If the monitoring signal returns to normal after this intervention cycle is executed once, it is determined that the blockage or abnormality has been resolved, and the parameters are gradually restored to those before the intervention.

8. The drilling method for ball cage type constant velocity universal joint based on adaptive cooling control according to claim 1, characterized in that, In the dynamic adjustment of CNC system parameters based on the acquired signals, the vibration acceleration signal is used as an additional criterion: when the vibration intensity continuously or instantaneously exceeds its safety threshold, regardless of the axial force and temperature signals, an adjustment command containing deceleration and enhanced cooling instructions is generated.

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