A milling mechanism and method for a composite lathe

Abstract

The application relates to the technical field of precision machining machine tools, and discloses a milling mechanism and method for a compound lathe, which comprises a milling execution module for milling a workpiece, a workpiece fixing module for clamping and driving the workpiece, an auxiliary supporting module, and a control module; the auxiliary supporting module is used for providing dynamic support for the workpiece during milling, and comprises a supporting assembly, a displacement driving unit, a detection unit, and a position calibration unit; the supporting assembly is used for being in contact with the surface of the workpiece; the displacement driving unit is connected with the supporting assembly and is used for driving the supporting assembly to move along the axial direction of the workpiece. According to the application, the auxiliary supporting module is arranged, the static deflection deformation problem of an elongated shaft caused by insufficient rigidity of the elongated shaft is solved, the module provides accurate radial supporting force by tracking a milling point in real time, the bending of the workpiece during machining is directly compensated, the straightness, cylindricity and other geometric tolerances of the workpiece are ensured, and the machining geometric precision is improved.

Description

Technical Field

[0001] This invention relates to the field of precision machining tool technology, and more specifically, to a milling mechanism and method for a composite lathe. Background Technology

[0002] Composite lathes integrate multiple machining functions such as turning, milling, and drilling, enabling multiple machining operations to be completed in a single workpiece clamping, significantly improving machining accuracy and efficiency. However, when milling keyways, planes, or helical grooves on slender shaft workpieces (such as hydraulic piston rods and drive shafts in the aerospace field), the workpiece is only clamped at both ends, and the middle part will experience significant deflection deformation and machining chatter due to insufficient rigidity.

[0003] Currently, traditional solutions mainly fall into two categories: one is to use a static center rest or follow rest to provide intermediate support. However, such devices cannot follow the movement of the milling point, and manual adjustment is required when the machining position changes, resulting in low efficiency and an inability to suppress high-frequency chatter caused by intermittent cutting. The second approach is to reduce cutting forces by significantly reducing cutting parameters (feed rate, depth of cut), but this severely impacts machining efficiency and often fails to meet ultra-high precision requirements.

[0004] Therefore, the existing technology lacks an intelligent auxiliary support scheme that can dynamically follow the milling point, provide adaptive support force in real time, and actively suppress machining chatter. This has become a key technical bottleneck restricting the efficient and high-quality machining of slender workpieces by composite lathes. Summary of the Invention

[0005] The purpose of this invention is to provide a milling mechanism and method for a composite lathe to solve the aforementioned technical problems.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0007] The present invention provides a milling mechanism for a composite lathe, comprising: a milling execution module for milling a workpiece, a workpiece fixing module for clamping and driving the workpiece, an auxiliary support module, and a control module;

[0008] The auxiliary support module is used to provide dynamic support for the workpiece during milling, and includes:

[0009] Support components for contact with the workpiece surface;

[0010] A displacement driving unit, connected to the support assembly, is used to drive it to move along the workpiece axial direction;

[0011] A micro-compensation drive unit is connected to the support component and is used to drive it to make micro-adjustments to radial displacement.

[0012] a detection unit integrated on the support assembly, configured to detect the contact force and vibration signal between the support assembly and the workpiece in real time;

[0013] a position calibration unit configured to automatically and accurately obtain the spatial geometric position of the workpiece before machining;

[0014] the control module is in communication connection with the displacement driving unit, the micro-compensation driving unit and the detection unit, and is configured to:

[0015] based on the milling feed shaft position information provided by the numerical control system and the workpiece axis line model established by the position calibration unit, the displacement driving unit is controlled to make the support assembly move synchronously with the milling machining point;

[0016] based on the contact force signal fed back by the detection unit, the micro-compensation driving unit is controlled to maintain the support force in a preset range;

[0017] based on the vibration signal fed back by the detection unit, when the chatter is identified, the micro-compensation driving unit is controlled to perform high-frequency micro-displacement compensation.

[0018] Preferably, the support assembly comprises a base and a V-shaped roller seat slidingly arranged on the base, and the rotation axes of the plurality of rollers on the roller seat are parallel to the workpiece axis.

[0019] Preferably, the surface of each roller on the roller seat is covered with an elastic material layer.

[0020] Preferably, the detection unit comprises a force sensor arranged on the roller seat and a vibration sensor for detecting vibration acceleration.

[0021] Preferably, the displacement driving unit is a cross slide module, and the base is connected with the cross slide module.

[0022] Preferably, the micro-compensation driving unit is a micro-driver installed between the base and the roller seat.

[0023] Preferably, the position calibration unit is a pair of trigger probes fixedly installed on one side of the workpiece fixing module.

[0024] Preferably, the milling execution module comprises a multi-directional linear driving unit and a milling head connected with the multi-directional linear driving unit.

[0025] Preferably, the workpiece fixing module comprises a clamping unit and a contact unit arranged opposite to the clamping unit.

[0026] A milling method of a composite lathe, comprising the following operation steps:

[0027] S100: clamping the workpiece on the workpiece fixing module;

[0028] S200: control the support assembly of the auxiliary support module to move to the predetermined support position of the workpiece, and establish the preset initial support force;

[0029] S300: start the milling execution module for milling processing, while performing:

[0030] S301: control the support assembly and the milling processing point to move synchronously along the axial direction of the workpiece;

[0031] S302: real-time detection of the contact force and vibration signal between the support assembly and the workpiece by the detection unit, based on the real-time detection of the contact force, dynamically adjusting the support position to maintain a constant support force;

[0032] S303: based on the real-time detection of the vibration signal, when the chatter is identified, control the support assembly to perform high-frequency micro-amplitude compensation motion;

[0033] S400: when a single segment processing is completed or a tool change is needed, control the support assembly to retreat radially from the surface of the workpiece, and after the milling execution module is in place, re-approach and establish support.

[0034] The beneficial effects of the present application are:

[0035] The present application sets up an auxiliary support module, which directly compensates the bending of the workpiece during processing by real-time tracking of the milling point and providing accurate radial support force, ensuring the straightness, cylindricity and other geometric tolerances of the workpiece, and improving the processing geometric precision.

[0036] In addition, for the problem of surface vibration caused by high-frequency chatter induced by intermittent cutting during milling, the detection unit in the auxiliary support module captures the vibration signal in real time, and the micro-compensation driving unit is driven by the control module to perform high-frequency micro-displacement compensation, effectively suppressing the generation of chatter, thereby improving the processing surface quality, and achieving the purpose of improving the processing precision. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a structural schematic view of a milling mechanism for a composite lathe of the present application;

[0038] Figure 2 is a structural schematic view of the milling mechanism for the composite lathe of the present application, the milling execution module, the workpiece fixing module and the auxiliary support module;

[0039] Figure 3 is a structural schematic view of the auxiliary support module of the milling mechanism for the composite lathe of the present application;

[0040] Figure 4is a relationship block diagram among modules of a milling mechanism of a composite lathe according to the present application;

[0041] Figure 5 is a work flow chart of a milling method of a composite lathe according to the present application.

[0042] In the figure: 10, machine tool main body; 20, milling execution module; 30, workpiece fixing module; 40, auxiliary support module; 401, base; 402, roller seat; 403, force sensor; 404, vibration sensor; 405, cross slide module; 406, micro driver; 408, trigger probe. DETAILED DESCRIPTION

[0043] The subject matter described herein will now be discussed with reference to example implementations. It should be understood that the discussion of these implementations is merely meant to provide a better understanding of the subject matter described herein and can be changed in function and arrangement without departing from the scope of the present description. Various processes or components can be omitted, substituted, or added according to desired implementations. Additionally, features described with respect to some examples can be combined in other examples.

[0044] Please see Figures 1 to 5 A milling mechanism for a composite lathe, comprising: a machine tool main body 10, in which a milling execution module 20, a workpiece fixing module 30, an auxiliary support module 40, and a control module are respectively arranged on a preset machining station in the machine tool main body 10. The milling execution module 20 comprises a multi-directional linear driving unit (such as X, Y, Z axis slides) and a milling head mounted thereon, for performing various types of milling machining. The workpiece fixing module 30 comprises a clamping unit (such as a spindle chuck) for clamping one end of a workpiece and a resisting unit (such as a tailstock center) for axially resisting the other end of the workpiece, to realize clamping and rotary driving of the workpiece.

[0045] The auxiliary support module 40 is used to provide dynamic support for the workpiece during milling, and specifically comprises: a support assembly, a displacement driving unit, a micro compensation driving unit, a detection unit, and a position calibration unit. The support assembly comprises a base 401 and a V-shaped roller seat 402 slidingly arranged on the base 401, three rollers are uniformly arranged on the two inclined surfaces of the roller seat 402, and the rotation axes of the rollers are parallel to the axis of the workpiece, to realize low-friction linear contact with the rotating workpiece, and the surface of the roller is wrapped with a layer of elastic material such as polyurethane (PU) or engineering rubber, to prevent scratching the surface of the precision workpiece and absorb part of the high-frequency vibration.

[0046] The displacement driving unit is connected with the base 401 in the support assembly, and is used for driving the whole support assembly to move along the workpiece axis in a large range; preferably, a cross slide module 405 is adopted, which includes X-axis driving part and Y-axis driving part perpendicular to each other; the X-axis driving part realizes left and right transverse movement of the support assembly, and the Y-axis driving part realizes front and back movement of the support assembly, so as to meet the use requirement of different support positions.

[0047] The micro compensation driving unit is installed between the base 401 and the roller seat 402, and is used for driving the roller seat 402 to move vertically relative to the base 401 with micron-level precision; generally, one of a piezoelectric ceramic driver or a high-precision servo electric cylinder is adopted, and the stroke range is usually ±0.1mm to ±0.5mm.

[0048] The detection unit is integrated on the support assembly, and is used for detecting the contact force and vibration signal between the support assembly and the workpiece in real time; specifically, the detection unit includes a force sensor 403 and a vibration sensor 404; the force sensor 403 is preferably a micro strain or piezoelectric force sensor 403, and is installed on the roller bearing load path, and is used for directly measuring the radial contact force of the support assembly on the workpiece; the vibration sensor 404 is preferably a micro three-axis accelerometer, and is installed on the roller seat 402 or the base 401, and is used for detecting the vibration acceleration signal of the workpiece in real time during machining.

[0049] The position calibration unit is integrated on the machining work station of the machine tool main body 10, and is used for automatically and accurately obtaining the space geometric position of the clamped workpiece before machining; the position calibration unit generally includes two high-precision trigger type probes 408, which are respectively fixedly installed on the machining work station at specific positions close to the clamping unit and the abutting unit, and the accurate space coordinates of the probes are calibrated and stored in the machine tool coordinate system; during calibration, the control module drives the workpiece to rotate slowly, and when the outer circular surface of the workpiece triggers the two probes in turn, the control module synchronously records the spindle angle at the triggering moment; based on the fixed coordinates of the probes, the triggering angle and the workpiece radius information, the control module can automatically calculate the key center coordinates of the two ends of the workpiece, so as to provide accurate initial data for establishing the workpiece axis line model.

[0050] The control module is in communication connection with the displacement driving unit, the micro compensation driving unit, the detection unit and the numerical control system of the combined lathe; the hardware can be integrated in the numerical control system of the lathe or be an independent PLC / industrial computer; the control module is configured to execute the following core control strategies:

[0051] Follow-up control: the support assembly moves in linkage of the X-axis and the Y-axis in the horizontal plane according to the real-time axial position of the milling point and the preset workpiece axis line model, so as to realize synchronous tracking and accurate centering of the support point to the milling point;

[0052] Constant force control: Based on the contact force signal fed back by the force sensor 403, the output of the micro compensation driving unit in the vertical direction (Z axis) is adjusted in a closed loop to dynamically maintain the support force of the support assembly on the workpiece constant at a preset value;

[0053] Chatter suppression control: Based on the signal fed back by the vibration sensor 404, the chatter characteristics generated in the milling process are identified in real time, and the micro compensation driving unit is driven to generate a micro-amplitude compensation motion of the same frequency and opposite phase in the vertical direction (Z axis) to actively suppress the workpiece vibration;

[0054] Intelligent avoidance control: According to the process state information of the numerical control system (such as tool number, machining code), when non-milling process or tool changing is required, the support assembly is automatically controlled to retreat from the workpiece along the preset path and move to the safe standby position, and then automatically reset during machining, realizing safe cooperation with the composite machining process.

[0055] The designed milling mechanism for the composite lathe has the following specific working process:

[0056] For clarity, the machine tool coordinate system is defined as follows: the direction parallel to the workpiece spindle axis (i.e. the workpiece axial direction) is the X axis (left-right movement), the direction perpendicular to the workpiece axis in the horizontal plane is the Y axis (forward-backward movement), and the vertical direction perpendicular to the horizontal plane is the Z axis (up-down movement).

[0057] Step one, system preparation and workpiece calibration:

[0058] After the workpiece is clamped, the calibration program is started, and the control module automatically obtains the center coordinates of the key sections at both ends of the workpiece through the calibration unit. Based on these two sets of coordinate data, the control module establishes a spatial geometric model of the actual rotation axis of the workpiece. This model can be simplified as a straight line equation Y=kX+b in the horizontal plane (X-Y plane), which accurately describes the ideal Y coordinate corresponding to any X coordinate position on the workpiece axis, providing a reference for all subsequent movements.

[0059] Step two, initial support position establishment and constant force preloading:

[0060] The control module calculates the axial (X axis) coordinate X support of the initial support point according to the start and end positions of the milling machining program (usually located at the midpoint of the machining interval); then, the following actions are performed in sequence:

[0061] Axial (X direction) positioning: control the X axis servo driver of the displacement driving unit to act, accurately moving the entire support assembly to the X support coordinate position;

[0062] Horizontal radial (Y direction) centering: move the X supportSubstitute the established axial line model Y=kX+b in step one, calculate the ideal Y coordinate Y corresponding to the axial position support ;

[0063] Vertical direction (Z direction) contact and force loading: the control module controls the micro-compensation driving unit to act, so that the micro-compensation driving unit starts to drive the roller seat 402 to slowly move upward, until the roller on the roller seat 402 contacts the lower surface of the workpiece, and the contact pressure is monitored in real time through the force sensor 403, and when the pressure reaches a preset initial slight value, the micro-compensation driving unit stops driving;

[0064] Constant force loading is completed: the control module immediately starts the active constant force control mode with a preset final target support force (for example, 20N) as the set value; in this mode, the control module continues to close-loop adjust the Z-axis output of the micro-compensation driving unit, finely increases the support force, until the target value is quickly and smoothly reached and stabilized; at this time, the accurate and stable initial support preloading of the workpiece is completed.

[0065] Step three, milling processing and adaptive follow-up support:

[0066] Start the milling program and enter the core processing stage, and the control module synchronously executes the following core functions to constitute a complete adaptive follow-up support:

[0067] Double-axis linkage position tracking (follow-up):

[0068] Axial (X direction) tracking: the control module reads the X-axis coordinate X of the milling tool tip in the machine tool coordinate system in real time at a preset frequency tool ;

[0069] Target position calculation: according to the preset support strategy (for example, the support point slightly leads the milling point to better resist the cutting force), the target X-axis coordinate of the support point is calculated: X target =X tool +ΔX (where ΔX is a preset axial offset, for example, -0.3 mm);

[0070] Horizontal radial (Y direction) matching: substitute X target into the axial line model Y=kX+b established in step one to directly solve the corresponding Y-axis target coordinate: Y target =kX target +b;

[0071] Instruction execution: the control module takes (X target , Y target ) as real-time position instructions, and simultaneously sends it to the X-axis and Y-axis servo drivers of the displacement driving unit, so that the two-axis servo systems perform precise interpolation motion, drive the support roller center to move cooperatively in the horizontal plane, and realize accurate tracking and centering of the support point to the milling point;

[0072] Dynamic constant force maintenance: During the follow-up process, the force sensor 403 continuously feeds back the actual support force F. act The constant force controller of the control module will F act With the set value F set The force error is compared and calculated, and the output of the micro-compensation drive unit in the Z-axis direction is dynamically adjusted. Through its high-frequency, micro-amplitude displacement changes, it quickly compensates for the changes in support force caused by cutting force fluctuations, workpiece roundness errors, etc., thereby enabling F act Stable at F set Within the range of ±δ (e.g., ±1N);

[0073] Active chatter suppression: The vibration sensor 404 monitors the machining vibration signal in real time. The control module performs real-time spectrum analysis on the signal. When the vibration signal is found to contain characteristic frequency components related to the number of milling cutter teeth and spindle speed, and the amplitude exceeds the safety threshold, chatter is immediately determined to have occurred. Subsequently, the control module activates the vibration suppression algorithm (such as adaptive feedforward control based on the LMS algorithm) to drive the micro-compensation drive unit to generate a high-frequency micro-amplitude displacement in the Z-axis direction with the same frequency and opposite phase as the vibration signal, thereby actively canceling the vibration of the workpiece, effectively suppressing chatter, and ensuring the quality of the machined surface.

[0074] Step 4, Intelligent Retreat and Process Collaboration:

[0075] When a milling operation is completed, or when the CNC system issues a command to change tools or switch to other operations such as turning, the control module learns of this status change in real time through the communication interface; to avoid interference between the support components and the moving tool, rotating workpiece, or other parts, the control module immediately executes intelligent avoidance logic:

[0076] First, the micro-compensation drive unit is controlled to retract in the Z-axis direction, causing the support roller to disengage from the workpiece. Next, the Y-axis of the displacement drive unit is driven, causing the support assembly to move away from the workpiece in the horizontal radial direction. Finally, the X-axis of the displacement drive unit can be driven as needed to move the entire support assembly to a preset safe standby position away from the machining area. The support assembly remains in this safe position throughout the entire non-milling process.

[0077] Step 5, Loop Support and Process End:

[0078] When the machining program calls the milling operation again, the control module controls the support assembly to quickly move from the safe standby position to the new support starting point, and repeats the initial support establishment process in step two and the adaptive follow-up support process in step three; this cycle continues until all milling operations on the workpiece are completed. Finally, the control module controls the support assembly to completely retract to a safe position, and the operator can safely unload the machined workpiece.

[0079] The specific working process of the present application establishes a geometric reference by high-precision automatic calibration, realizes large-range and accurate tracking and positioning of the support point through the displacement driving unit (X / Y axis), and relies on the micro compensation driving unit (Z axis) to perform precise constant force control and active vibration suppression, forming a complete and intelligent adaptive follow-up support closed loop. This process improves the rigidity, stability and machining precision of the composite lathe when milling slender and thin-walled parts, and realizes efficient, high-quality and safe composite machining.

[0080] The above describes the embodiments of the present application, but the present application is not limited to the above specific embodiments, and the above specific embodiments are only illustrative and not limiting. Those skilled in the art can make many forms under the inspiration of the present application, which all belong to the protection of the present application.

Claims

1. A milling mechanism for a composite lathe, characterized in that, include: A milling execution module for milling workpieces, a workpiece fixing module for clamping and driving workpieces, an auxiliary support module, and a control module; The auxiliary support module is used to provide dynamic support for the workpiece during milling, and includes: Support components for contact with the workpiece surface; A displacement driving unit, connected to the support assembly, is used to drive it to move along the workpiece axial direction; A micro-compensation drive unit is connected to the support component and is used to drive it to make micro-adjustments to radial displacement. The detection unit, integrated on the support assembly, is used to detect the contact force and vibration signal between the support assembly and the workpiece in real time. A position calibration unit is used to automatically and accurately obtain the spatial geometric position of the workpiece before processing; The control module is communicatively connected to the displacement drive unit, the micro-compensation drive unit, and the detection unit, respectively, and is configured to execute as follows: Based on the milling feed axis position information and the workpiece axis centerline model established by the position calibration unit provided by the CNC system, the displacement drive unit is controlled to make the support component move synchronously with the milling machining point. Based on the contact force signal fed back by the detection unit, the micro-compensation drive unit is controlled to maintain the support force within a preset range; Based on the vibration signal fed back by the detection unit, when flutter is detected, the micro-compensation drive unit is controlled to perform high-frequency micro-displacement compensation.

2. A milling mechanism for a composite lathe according to claim 1, characterized in that, The support assembly includes a base and a V-shaped roller seat slidably disposed on the base, wherein the rotation axes of the plurality of rollers on the roller seat are parallel to the workpiece axis.

3. A milling mechanism for a composite lathe according to claim 2, characterized in that, The surface of each roller on the roller seat is covered with a layer of elastic material.

4. A milling mechanism for a composite lathe according to claim 2, characterized in that, The detection unit includes a force sensor mounted on the roller seat and a vibration sensor for detecting vibration acceleration.

5. A milling mechanism for a composite lathe according to claim 2, characterized in that, The displacement driving unit is a cross slide module, and the base is connected to the cross slide module.

6. A milling mechanism for a composite lathe according to claim 2, characterized in that, The micro-compensation drive unit is a miniature driver installed between the base and the roller seat.

7. A milling mechanism for a composite lathe according to claim 1, characterized in that, The position calibration unit is a pair of trigger-type probes fixedly installed on one side of the workpiece fixing module.

8. A milling mechanism for a composite lathe according to claim 1, characterized in that, The milling execution module includes a multi-directional linear drive unit and a milling head connected to the multi-directional linear drive unit.

9. A milling mechanism for a composite lathe according to claim 1, characterized in that, The workpiece fixing module includes a clamping unit and an abutting unit disposed opposite to the clamping unit.

10. A milling method for a composite lathe, using a milling mechanism for a composite lathe as described in any one of claims 1-9, characterized in that, The following steps are included: S100: Clamp the workpiece onto the workpiece fixing module; S200: Controls the movement of the support components of the auxiliary support module to the predetermined support position of the workpiece and establishes a preset initial support force; S300: Start the milling execution module to perform milling operations, and simultaneously execute: S301: Control the support assembly and the milling point to move synchronously along the workpiece axis; S302: The contact force and vibration signal between the support component and the workpiece are detected in real time by the detection unit. Based on the real-time detected contact force, the support position is dynamically adjusted to maintain a constant support force. S303: Based on the real-time detected vibration signal, when flutter is detected, the support component is controlled to perform high-frequency micro-amplitude compensation movement; S400: When a single-segment machining is completed or a tool change is required, the support component is controlled to radially retract from the workpiece surface, and then approach and establish support again after the milling execution module is in place.

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