Inclined rail type double-spindle double-tool-turret turning and milling combined machining center and control method thereof

Abstract

The invention provides an inclined rail type double-main-shaft double-tool-tower turning and milling combined machining center, and relates to the technical field of machine tools for executing different machining, when long-shaft workpieces are machined, a CNC numerical control system can control tools on a main tool assembly and tools on an auxiliary tool assembly, and meanwhile, the workpieces are symmetrically cut from the upper side and the lower side of the workpieces. When the outer circle is turned, the upper cutter feeds downwards for cutting, the lower cutter feeds upwards for cutting, and the cutting forces applied to the radial direction of the workpiece by the two cutters are equal in magnitude and opposite in direction, so that the cutting forces are mutually counteracted. The symmetrical cutting force directly counteracts the radial bending moment possibly generated by the workpiece when a single cutter is used for cutting, so that the bending resistance effect is realized, and the device is particularly suitable for precision machining of slender shafts and thin-walled cylinder workpieces.

Description

Technical Field

[0001] This invention relates to the field of machine tool technology for performing various machining operations, specifically to a slant-rail type dual-spindle dual-turret turning and milling composite machining center and its control method. Background Technology

[0002] A mill-turn machining center is a CNC machine tool that integrates turning and milling functions. It can complete multi-process machining of complex parts (such as shafts and discs) on a single machine, effectively reducing the number of workpiece clamping operations and the machine tool footprint, while improving machining accuracy and production efficiency. The slant rail layout facilitates chip removal, the dual-spindle configuration allows for simultaneous machining from both ends of the workpiece, and the dual turrets support more tools or enable parallel cutting. This represents an important development direction for high-end CNC equipment.

[0003] In existing technologies, significant challenges remain when machining workpieces with poor rigidity, such as slender shafts and thin-walled cylinders. When machining with a single spindle and tailstock or single turret, the unidirectional cutting force in the radial direction can cause workpiece bending deformation, affecting dimensional accuracy and shape tolerances. Some equipment with dual spindles or dual turrets often has turrets arranged on the same side or lacks coordinated motion axis planning, making it impossible to apply symmetrical and balanced cutting forces from both sides of the workpiece. Furthermore, during process integration and workpiece transfer, maintaining and utilizing the high rigidity advantage of dual-spindle clamping to prevent cumulative deformation of the workpiece under repeated clamping or unilateral force is a challenge.

[0004] Therefore, a slant-rail type dual-spindle dual-turret turning and milling composite machining center and its control method are provided. Summary of the Invention

[0005] To address the problems mentioned in the background art, the present invention provides the following technical solution: a slant rail type dual spindle dual turret turning and milling composite machining center, comprising: a frame and a CNC numerical control system, wherein the frame is a 45° slant rail type frame and the frame is mounted on an inclined slope; The frame has a main spindle and a secondary spindle arranged coaxially in the middle of the inclined surface; A main Z-axis is fixed on an inclined plane on one side of the spindle, a main X-axis is provided on the movable end of the main Z-axis, and a main tool assembly is provided on the movable end of the main X-axis; A secondary Z-axis is fixed on an inclined plane on one side of the secondary spindle, a secondary X-axis is provided on the movable end of the secondary Z-axis, and a secondary tool assembly is provided on the movable end of the secondary X-axis. The main tool assembly and the auxiliary tool assembly are diagonally opposite each other.

[0006] Furthermore, the spindle includes a spindle box fixed on an inclined plane, and a spindle assembly is provided inside the spindle box. The spindle assembly is driven by a servo motor located at the end of the spindle box via a pulley set. The spindle box is provided with a brake assembly for braking the spindle assembly.

[0007] Furthermore, the main tool assembly includes a turret housing, with a tool disc at the output end and a turret motor mounting bracket at the input end for fixing the turret motor.

[0008] Furthermore, a Y-axis is also provided between the main tool assembly and the main X-axis. The Y-axis is fixed on the output end of the main X-axis, and the turret box is fixedly connected to the output end of the Y-axis.

[0009] Furthermore, the secondary tool assembly has the same structure as the main tool assembly.

[0010] Furthermore, the secondary spindle includes a secondary spindle box fixed on the inclined plane, a secondary spindle assembly is provided inside the secondary spindle box, and a secondary spindle motor for driving the secondary spindle assembly is provided on the input end of the secondary spindle box. The secondary spindle motor and the secondary spindle assembly are driven by a pulley set.

[0011] A control method, applied to the slant-rail type dual-spindle dual-turret turning-milling composite machining center according to any one of claims 1 to 6, the control method comprising the following steps: S1: Obtain the workpiece data to be processed and import the workpiece data into the CNC numerical control system; S2: The CNC system plans the collaborative machining path of the main tool assembly and the auxiliary tool assembly based on the workpiece data; S3: Clamp the workpiece between the main spindle and the sub-spindle, so that the clamping end of the main spindle and the clamping end of the sub-spindle together fix the two ends of the workpiece. S4: Start the main spindle and the sub-spindle, and control them to rotate synchronously at the same speed; S5: Based on the collaborative machining path, control the main tool assembly and the auxiliary tool assembly to machine the rotating workpiece; wherein, the collaborative machining path is planned as follows: This ensures that the tools on the main tool assembly and the tools on the auxiliary tool assembly are located at the same radial position on the workpiece during machining. The main Z-axis and the auxiliary Z-axis are controlled to feed along the axis of the workpiece, and their feed directions are opposite and their feed speeds are synchronized. The main X-axis and the secondary X-axis are controlled to feed in a direction perpendicular to the workpiece axis, and their feed directions are opposite, so that the machining trajectory of the tool on the main tool assembly and the machining trajectory of the tool on the secondary tool assembly are tangent or coincident at the same radial position of the workpiece.

[0012] Furthermore, in step S5, the CNC system performs synchronous interpolation control on the main Z-axis, main X-axis, secondary Z-axis, and secondary X-axis. Specifically, the CNC system generates a unified interpolation command based on the collaborative machining path. This interpolation command simultaneously drives the servo motors of the main Z-axis and the secondary Z-axis to run at speeds of equal magnitude but opposite directions, and simultaneously drives the servo motors of the main X-axis and the secondary X-axis to run at speeds of equal magnitude but opposite directions, thereby enabling the tools on the main tool assembly and the secondary tool assembly to perform symmetrical cutting on the workpiece along the planned trajectory.

[0013] Furthermore, the method also includes the step of transferring and relaying the workpiece after machining one end of the workpiece: S6: The main spindle and the secondary spindle stop rotating; S7: The main tool assembly and the auxiliary tool assembly return to the safe position; S8: The sub-spindle holds the workpiece and moves it axially away from the spindle, causing the workpiece to disengage from the clamping end of the spindle. S9: After the sub-spindle drives the workpiece to rotate to a predetermined angle, the sub-spindle moves axially to send the machined section of the workpiece into the machining range of the sub-tool assembly, while positioning the unmachined section of the workpiece within the machining range of the main tool assembly. S10: Repeat steps S4 to S5, where the main tool assembly processes the unprocessed section of the workpiece, while the auxiliary tool assembly performs new processing operations on the processed section of the workpiece.

[0014] Beneficial effects The present invention has the following beneficial effects: (1) When machining long shaft-type workpieces, the CNC system of this invention can control the tools on the main tool assembly and the auxiliary tool assembly to simultaneously cut symmetrically from the upper and lower sides of the workpiece. When turning the outer diameter, the upper tool feeds downward and the lower tool feeds upward. The cutting forces applied to the radial direction of the workpiece by the two tools are equal in magnitude and opposite in direction, thus canceling each other out. The symmetrical cutting force directly cancels out the radial bending moment that may be generated in the workpiece when a single tool is cutting, achieving the effect of resisting bending. It is particularly suitable for precision machining of slender shafts and thin-walled cylindrical workpieces.

[0015] (2) The main Z-axis of this invention drives the main tool assembly to feed in one direction along the workpiece axis, while the secondary Z-axis 7 drives the secondary tool assembly to feed in the opposite direction at the same speed. The two tools maintain a constant relative position in the workpiece axis. The main X-axis drives the main tool assembly to feed radially toward the center of the workpiece, while the secondary X-axis drives the secondary tool assembly to feed radially toward the center of the workpiece. Since the two tools are pre-set at the upper and lower symmetrical points of the workpiece, they contact the workpiece simultaneously and perform cutting. The tool of the main tool assembly generates a downward cutting force F1 on the workpiece, and the tool of the secondary tool assembly generates an upward cutting force F2 on the workpiece. Under ideal alignment, F1 and F2 are equal in magnitude, opposite in direction, and act on the same straight line, so they cancel each other out, and the net force is zero. The workpiece is no longer subjected to a resultant force that causes it to bend in the radial direction, thus maintaining a straight machining state and significantly improving machining accuracy, especially for workpieces with a large length-to-diameter ratio.

[0016] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0017] Figure 1 This is an isometric view of the entire invention.

[0018] Figure 2 These are three views of the secondary spindle of the present invention.

[0019] Figure 3 These are the three views of the main axis of this invention.

[0020] Figure 4 These are three views of the main tool assembly of the present invention.

[0021] Figure 5 This is a flowchart of the entire invention.

[0022] The components in the diagram are labeled as follows: Frame 1, Spindle 2, Spindle box 21, Spindle assembly 22, Brake assembly 24, Main Z-axis 3, Main X-axis 4, Main tool assembly 5, Turret box 51, Tool head 52, Y-axis 53, Motor mounting base 54, Turret power motor mounting base 55, Sub-spindle 6, Sub-spindle box 61, Sub-spindle assembly 62, Sub-spindle motor 63, Sub-Z-axis 7, Sub-X-axis 8, Sub-tool assembly 9. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figure 1 The present invention provides a technical solution: a slant rail type dual spindle dual turret turning and milling composite machining center, including: a frame 1 and a CNC numerical control system, the frame 1 is a 45° slant rail type frame, the frame 1 is set on an inclined slope; The inclined surface of the frame 1 is provided with a main spindle 2 and a secondary spindle 6 arranged coaxially. A main Z-axis 3 fixed on an inclined plane is provided on one side of the main spindle 2, a main X-axis 4 is provided on the movable end of the main Z-axis 3, and a main tool assembly 5 is provided on the movable end of the main X-axis 4; A secondary spindle 6 has a secondary Z-axis 7 fixed on an inclined plane on one side, a secondary X-axis 8 on the movable end of the secondary Z-axis 7, and a secondary tool assembly 9 on the movable end of the secondary X-axis 8. The main tool assembly 5 and the auxiliary tool assembly 9 are diagonally opposite each other.

[0025] Main spindle 2, main Z-axis 3, main X-axis 4, main tool assembly 5, sub-spindle 6, sub-Z-axis 7, sub-X-axis 8, and sub-tool assembly 9 all adopt existing technologies.

[0026] The most common combination of main Z-axis 3, main X-axis 4, secondary Z-axis 7, and secondary X-axis 8 is a combination of servo motor, lead screw, and slider. The servo motor drives the lead screw to rotate, which in turn drives the slider to slide.

[0027] In practical implementation, the frame 1 serves as the basic support structure for the entire equipment, and its working surface is set as an inclined plane at a 45-degree angle to the horizontal plane. The main function of this inclined rail layout is to allow the chips generated during processing to slide down naturally under the influence of gravity, detaching them from the working area, thereby keeping the processing area clean and preventing chip accumulation from affecting processing accuracy or tool life.

[0028] The main spindle 2 and the auxiliary spindle 6 are fixed in the middle region of the inclined plane by their respective mounting bases with their axes overlapping.

[0029] When adapting to end face machining, the following configuration can be selected: the sub-spindle 6 is fixed to the inclined surface via axis A, which is a combination of servo motor, lead screw and slider. The sub-spindle 6 is fixed on the slider, and the servo motor drives the lead screw to make the slider slide. The guide rail base of the main Z-axis 3 is directly fixed to the inclined surface on one side of the main spindle 2 by bolts; similarly, the guide rail base of the secondary Z-axis 7 is directly fixed to the inclined surface on one side of the secondary spindle 6 by bolts.

[0030] The main tool assembly 5 is suspended above the main spindle 2 via its kinematic chain (main Z-axis 3, main X-axis 4); the secondary tool assembly 9 is suspended below the secondary spindle 6 via its kinematic chain (secondary Z-axis 7, secondary X-axis 8), and the two are diagonally distributed in space.

[0031] This layout allows the main tool assembly 5 and the auxiliary tool assembly 9 to approach the workpiece from two opposing directions, above and below, during machining.

[0032] When machining long shaft workpieces, the CNC system can control the tools on the main tool assembly 5 and the auxiliary tool assembly 9 to perform symmetrical cutting from the upper and lower sides of the workpiece.

[0033] For example, when turning an outer diameter, the upper tool feeds downwards to cut, while the lower tool feeds upwards to cut. The two tools apply equal and opposite cutting forces to the workpiece in the radial direction, thus canceling each other out.

[0034] This symmetrical cutting force directly counteracts the radial bending moment that a single tool might generate on the workpiece, achieving an anti-bending effect. It is particularly suitable for precision machining of slender shafts and thin-walled cylindrical workpieces.

[0035] Furthermore, the spindle 2 includes a spindle box 21 fixed on an inclined plane. The spindle box 21 is equipped with a spindle assembly 22. The spindle assembly 22 is driven by a servo motor located at the end of the spindle box 21 via a pulley set. The spindle box 21 is equipped with a brake assembly 24 for braking the spindle assembly 22.

[0036] In practice, the spindle box 21 is a rigid shell, which is fastened to the inclined surface of the frame 1 through its bottom surface.

[0037] The spindle assembly 22 (including spindle, bearing assembly, broaching mechanism, etc.) is installed in the internal cavity of the spindle box 21.

[0038] The drive servo motor is installed on the outside of the end of the spindle box 21. Its output shaft is connected to the input shaft of the spindle assembly 22 through a set of pulleys (including the drive pulley, the driven pulley and the transmission belt), which transmits power to the spindle assembly 22, thereby driving the clamping end (such as a chuck or collet) at its front end to rotate.

[0039] The brake assembly 24 is typically a hydraulically or pneumatically driven disc brake mechanism, mounted on the spindle box 21, with its brake pads acting on the brake disc of the spindle assembly 22. When an emergency stop or near-stop positioning of the spindle is required, the CNC system sends a signal, and the brake assembly 24 actuates, clamping the brake disc to achieve braking. This structure ensures that the spindle 2 can provide stable and precisely controllable high-speed torque.

[0040] In bending machining, spindle 2 and sub-spindle 6 must rotate in perfect synchronization. The CNC system controls the servo motors of spindle 2 and sub-spindle 6 separately to ensure that their speeds and phase angles remain highly consistent. This allows the workpiece, clamped at both ends, to rotate as a single unit at a uniform speed, providing a stable motion reference for the symmetrical cutting of the main tool assembly 5 and the sub-tool assembly 9. If the rotations at both ends are asynchronous, torsional stress will be generated inside the workpiece, which will not only fail to effectively counteract the radial cutting force but may also cause new deformations or vibrations.

[0041] Furthermore, the main tool assembly 5 includes a turret housing 51, the output end of which is provided with a tool disc 52, and the input end of the turret housing 51 is provided with a turret power motor mounting base 55 for fixing the turret power motor.

[0042] In practice, the turret motor (not marked in the figure) is fixed to the turret motor mounting base 55 with bolts, and its output shaft is connected to the indexing mechanism in the turret box 51 through a coupling or gear mechanism.

[0043] The turret housing 51 contains an indexing plate and a drive mechanism for driving the cutter head 52 to perform precise indexing.

[0044] The cutter head 52 is equipped with multiple tool holders for mounting various cutting tools such as turning tools, milling cutters, and drill bits.

[0045] When the CNC system issues a tool change command, the turret motor drives the indexing mechanism to rotate the tool head 52, moving the required tool to the working position and locking it.

[0046] The turret box 51 is an integrated functional module, and its base is connected to the movable slider of the Y-axis 53 by bolts.

[0047] When performing anti-bending machining, such as when symmetrical milling grooves are required from directly above and below the workpiece, the operator or CNC program will first call the Y-axis 53. The servo motor of the Y-axis 53 drives its slider to move, thereby causing the tools on the entire turret box 51 and the tool head 52 to make fine adjustments in the Y-axis direction (perpendicular to the inclined plane, i.e., close to the vertical direction).

[0048] By adjusting the Y-axis 53 of the main tool assembly 5 and the auxiliary tool assembly 9 respectively, the absolute coordinate positions of the two tools in the radial direction (i.e., the direction perpendicular to the workpiece axis) can be precisely set, ensuring that they are accurately located in the same radial plane passing through the workpiece axis and at the same depth during cutting. This is a prerequisite for achieving perfect counter-coupling (couple balance) of the cutting forces on both sides in a straight line. If there is a deviation in the radial position of the two tools, the cutting forces will not be completely offset, leaving a residual torque that causes the workpiece to deflect.

[0049] Furthermore, a Y-axis 53 is provided between the main tool assembly 5 and the main X-axis 4. The Y-axis 53 is fixed on the output end of the main X-axis 4, and the turret box 51 is fixedly connected to the output end of the Y-axis 53.

[0050] In practical implementation, the guide rail base of the Y-axis 53 is rigidly connected to the movable slider (i.e., its output end) of the main X-axis 4 by bolts. The Y-axis 53 inherits all the movements of the main X-axis 4 in the X direction (parallel to the inclined plane and perpendicular to the workpiece axis) and the Z direction (parallel to the workpiece axis).

[0051] The servo motor of Y-axis 53 drives its movable slider to move along the Y-axis guide rail, and the direction of movement is perpendicular to the slide plane of the main X-axis 4.

[0052] The turret box 51 is fixed to the Y-axis slider by bolts.

[0053] When machining requires adjusting the precise radial position of the tool on the workpiece, For example, when setting the tool before milling a symmetrical keyway, the CNC system controls the servo motor of the Y-axis 53 to move the turret box 51 and the tool along the Y direction until the tool tip reaches the Y-axis coordinate value set in the program.

[0054] In bending-resistant machining scenarios, the Y-axis 53 on the main tool assembly 5 and the auxiliary tool assembly 9 work independently but collaboratively. The CNC system calculates and instructs the two Y-axis 53 to move to the target position according to the machining path. This target position is usually symmetrical about the workpiece axis.

[0055] For example, the Y-coordinate of the main tool assembly 5 is set to +50.000mm, and the Y-coordinate of the auxiliary tool assembly 9 is set to -50.000mm (assuming the workpiece axis is the zero point in the Y direction). In this way, the two tools are precisely positioned at symmetrical points on both sides of the workpiece.

[0056] Furthermore, the secondary tool assembly 9 has the same structure as the main tool assembly 5.

[0057] In practice, the secondary tool assembly 9 has the same structure and components as the main tool assembly 5, including the turret box, tool head, turret power motor mounting base and Y-axis (not shown on the secondary tool assembly 9 in the figure, but its structure is the same, so it should be included).

[0058] The secondary tool assembly 9 is connected to the movable slider of the secondary X-axis 8 via its Y-axis base. Its working logic is completely consistent with that of the main tool assembly 5, and it can independently perform tool selection, indexing, and position adjustment in the Y-axis direction.

[0059] In the machining process to solve the bending problem, the secondary tool assembly 9 and the main tool assembly 5 form a symmetrical execution system.

[0060] The CNC system sends mirror or symmetrical motion commands to both.

[0061] For example, when the tool head 52 of the main tool assembly 5 selects the external turning tool at position 1, the tool head 52 of the auxiliary tool assembly 9 may select the external turning tool at a corresponding tool position (or other tools as required by the process). During feeding, the Y-axis movement of both is equal in value but opposite in sign; the movement of the X-axis and Z-axis also follows the principle of symmetry and synchronization.

[0062] This perfectly symmetrical hardware configuration is the physical basis for the software control algorithm to achieve force cancellation and counteract workpiece bending. The independence and symmetry of the two turrets enable the equipment to operate in a "mirror machining" mode, decomposing the cutting force that would otherwise be borne by a single tool and potentially deform the workpiece into two equal and opposite forces, which then cancel each other out within the workpiece.

[0063] Furthermore, the secondary spindle 6 includes a secondary spindle box 61 fixed on the inclined plane. The secondary spindle box 61 contains a secondary spindle assembly 62. The input end of the secondary spindle box 61 is provided with a secondary spindle motor 63 for driving the secondary spindle assembly 62. The secondary spindle motor 63 and the secondary spindle assembly 62 are driven by a belt pulley set.

[0064] In practice, the secondary spindle box 61 is fixed to the inclined surface of the frame 1 by bolts, and its axis is strictly aligned with the axis of the spindle box 21.

[0065] The sub-spindle assembly 62 is installed inside the sub-spindle box 61.

[0066] The secondary spindle motor 63 is bolted to the outer wall of the input end of the secondary spindle box 61. Its output shaft is connected to the input shaft of the secondary spindle assembly 62 through another set of independent pulleys, driving the secondary spindle assembly 62 and its front clamping end to rotate.

[0067] The sub-spindle 6 has the same rotation, positioning, and clamping functions as the spindle 2, and usually also has an independent braking system (not shown in the figure).

[0068] At the start of machining, spindle 2 and sub-spindle 6 move synchronously towards each other, together clamping both ends of the workpiece to form a "double-support" clamping state, which is an order of magnitude improvement in rigidity compared to traditional cantilever clamping (single spindle + tailstock).

[0069] In anti-bending collaborative machining, the core function of the sub-spindle 6 is to provide fully synchronized rotary motion with the main spindle 2 and reverse support for the workpiece. The CNC system ensures that the sub-spindle motor 63 strictly follows and synchronizes with the drive servo motor of the main spindle 2. When the main tool assembly 5 and the sub-tool assembly 9 perform symmetrical cutting, the workpiece may be subjected to axial cutting forces in addition to radial symmetrical cutting forces. At this time, the sub-spindle 6 not only provides rotary drive, but also provides support for the workpiece against axial cutting forces through its rigid connection with the main spindle 2, preventing the workpiece from shifting or bending in the axial direction, further enhancing the overall rigidity and stability of the machining system, and suppressing workpiece deformation from multiple dimensions.

[0070] A control method is applied to a slant-rail type dual-spindle dual-turret milling and turning machining center. The control method includes the following steps: S1: Obtain the workpiece data to be processed and import the workpiece data into the CNC numerical control system; In step S1, the operator imports the workpiece's three-dimensional model (such as a STEP file) or machining process parameters into the CNC numerical control system.

[0071] S2: The CNC system plans the collaborative machining path of the main tool assembly 5 and the auxiliary tool assembly 9 based on the workpiece data; In step S2, the CAM module or process planning module of the CNC system automatically or semi-automatically generates the machining paths for the main tool assembly 5 and the auxiliary tool assembly 9 based on the workpiece shape and machining requirements.

[0072] When planning the path, the CNC system will activate the "symmetric machining" mode specifically for processes that require high rigidity (such as turning of slender shafts and deep groove milling).

[0073] In this mode, the CNC system will automatically decompose and map a single-tool machining path into two spatially symmetrical paths, which are assigned to the main tool assembly 5 and the auxiliary tool assembly 9 respectively, and calculate the motion commands of each axis required to ensure that the tools on the two paths meet at the same radial position on the workpiece.

[0074] S3: Clamp the workpiece between the main spindle 2 and the auxiliary spindle 6, so that the clamping end of the main spindle 2 and the clamping end of the auxiliary spindle 6 together fix the two ends of the workpiece. In step S3, the main spindle 2 and the sub-spindle 6 clamp the workpiece together under the control of the CNC program.

[0075] S4: Start spindle 2 and sub-spindle 6, and control them to rotate synchronously at the same speed; In step S4, the CNC system controls the main spindle 2 and the sub-spindle 6 to rotate synchronously at the same speed (e.g., 1000 rpm).

[0076] S5: Based on the collaborative machining path, control the main tool assembly 5 and the auxiliary tool assembly 9 to machine the rotating workpiece; wherein, the collaborative machining path is planned as follows: The tools on the main tool assembly 5 and the tools on the auxiliary tool assembly 9 are positioned at the same radial position on the workpiece during machining. The main Z-axis 3 and the auxiliary Z-axis 7 are controlled to feed along the axis of the workpiece, and their feed directions are opposite and their feed speeds are synchronized. The main X-axis 4 and the secondary X-axis 8 are controlled to feed in a direction perpendicular to the workpiece axis, and their feed directions are opposite, so that the machining trajectory of the tool on the main tool assembly 5 and the machining trajectory of the tool on the secondary tool assembly 9 are tangent or coincident at the same radial position of the workpiece.

[0077] Step S5 is the direct implementation step of the anti-bending process.

[0078] The CNC system simultaneously sends coordinated movement commands to four linear axes (main Z-axis 3, main X-axis 4, secondary Z-axis 7, secondary X-axis 8) and two rotary spindles (main spindle 2, secondary spindle 6).

[0079] The specific cooperative relationship is as follows: the main Z-axis 3 drives the main tool assembly 5 to feed in one direction (e.g., to the right) along the workpiece axis, while the secondary Z-axis 7 drives the secondary tool assembly 9 to feed in the opposite direction (i.e., to the left) at the same speed. The two tools maintain a constant relative position along the workpiece axis.

[0080] The main X-axis 4 drives the main tool assembly 5 to feed radially toward the center of the workpiece (e.g., downwards), while the secondary X-axis 8 drives the secondary tool assembly 9 to also feed radially toward the center of the workpiece (i.e., upwards).

[0081] Since the two cutting tools are pre-positioned at symmetrical points above and below the workpiece, they simultaneously contact the workpiece and perform cutting. The cutting tool of the main tool assembly 5 generates a downward cutting force F1 on the workpiece, while the cutting tool of the secondary tool assembly 9 generates an upward cutting force F2 on the workpiece.

[0082] Under ideal alignment conditions, F1 and F2 are equal in magnitude, opposite in direction, and act along the same straight line, thus canceling each other out and resulting in a net force of zero. The workpiece is no longer subjected to a resultant force in the radial direction that would cause it to bend, thereby maintaining a straight machining state and significantly improving machining accuracy, especially for workpieces with a large length-to-diameter ratio.

[0083] Furthermore, in step S5, the CNC system performs synchronous interpolation control on the main Z-axis 3, main X-axis 4, secondary Z-axis 7, and secondary X-axis 8. Specifically, the CNC system generates a unified interpolation command based on the collaborative machining path. This interpolation command simultaneously drives the servo motors of the main Z-axis 3 and the secondary Z-axis 7 to run at speeds of equal magnitude but opposite directions, and simultaneously drives the servo motors of the main X-axis 4 and the secondary X-axis 8 to run at speeds of equal magnitude but opposite directions, thereby enabling the tools on the main tool assembly 5 and the secondary tool assembly 9 to perform symmetrical cutting on the workpiece along the planned trajectory.

[0084] In practice, the synchronous interpolation control in step S5 is achieved by the multi-axis linkage interpolator of the CNC system.

[0085] When executing a G-code program segment for a symmetrical milling profile (e.g., G01 X10. Z-5. F100), the interpolator does not directly assign it to a single axis group, but instead treats it as a "reference path".

[0086] The interpolator decomposes this path according to the logic of the "symmetric processing" mode.

[0087] For Z-axis motion: the reference path requires the tool to move 5mm in the negative Z-axis direction.

[0088] The interpolator generates a pair of sub-commands: instructing the servo motor of the main Z-axis 3 to drive the tool to move 2.5mm in the negative Z direction, and simultaneously instructing the servo motor of the secondary Z-axis 7 to drive another tool to move 2.5mm in the positive Z direction.

[0089] Both have the same speed (calculated based on a feed rate of F100) but in opposite directions.

[0090] The same applies to X-axis motion. These paired motion commands with strict mathematical relationships are encapsulated within a uniform interpolation cycle and sent simultaneously to the servo drives of all four axes.

[0091] The cutting tools on the main tool assembly 5 and the secondary tool assembly 9 move towards the center of the workpiece or along the workpiece contour from both sides of the workpiece along a perfectly symmetrical trajectory, much like mirror images. Because the movement is strictly synchronized and symmetrical, the contact time, cutting depth, and cutting angle of the two tools with the workpiece remain symmetrical. This ensures that the cutting forces generated on both sides remain equal in magnitude and opposite in direction throughout the entire dynamic machining process, achieving dynamic and continuous cancellation of workpiece bending deformation. This synchronous control based on low-level interpolation commands is more accurate, responds faster, and provides more stable and reliable anti-bending performance than control based solely on the sequence of program inputs.

[0092] Furthermore, the method also includes the step of transferring and relaying the workpiece after machining one end of the workpiece: S6: Main spindle 2 and secondary spindle 6 stop rotating; S7: Main tool assembly 5 and auxiliary tool assembly 9 return to the safe position; S8: The secondary spindle 6 holds the workpiece and moves it axially away from the spindle 2, so that the workpiece is released from the clamping end of the spindle 2. S9: After the sub-spindle 6 drives the workpiece to rotate to a predetermined angle, the sub-spindle 6 moves axially to send the machined section of the workpiece into the machining range of the sub-tool assembly 9, while positioning the unmachined section of the workpiece within the machining range of the main tool assembly 5. S10: Repeat steps S4 to S5, where the main tool assembly 5 processes the unprocessed section of the workpiece, while the auxiliary tool assembly 9 performs new processing operations on the processed section of the workpiece.

[0093] After the middle part of the machining is completed, the workpiece is transferred between the main spindle 2 and the sub-spindle 6 and the process continues to take advantage of the symmetrical machining.

[0094] Steps S6 and S7 are safety preparations for processing interruptions.

[0095] In step S8, the clamping end of the sub-spindle 6 remains clamped, and its entire sub-spindle housing 61 moves away from the spindle 2 along the guide rail direction of the sub-Z-axis 7 (i.e., the workpiece axis) under the drive of the servo motor, pulling the workpiece out of the chuck of the spindle 2. At this time, the workpiece is completely held by the sub-spindle 6.

[0096] Step S9 is the critical repositioning step.

[0097] The sub-spindle 6 first rotates the workpiece by a specific angle (such as 90 degrees or 180 degrees), which is determined by subsequent processes (e.g., machining features on the other side of the workpiece). Then, the sub-spindle 6 moves axially for precise positioning.

[0098] This movement has two purposes: First, move the area on the workpiece that was just machined by the spindle 2 (the end that was originally close to the spindle 2) to the machining range of the sub-tool assembly 9; Second, the unprocessed area on the other end of the workpiece is accurately positioned within the machining range of the main tool assembly 5. This is equivalent to "turning over" the workpiece and resetting the tool without disassembling it.

Claims

1. A slant-rail type dual-spindle dual-turret turning and milling machining center, comprising: The frame (1) and CNC numerical control system are characterized in that: the frame (1) is a 45° inclined rail frame, and the frame (1) is set on an inclined plane; a main spindle (2) and a secondary spindle (6) are coaxially arranged in the middle of the inclined plane of the frame (1); a main Z-axis (3) fixed on the inclined plane is provided on one side of the main spindle (2), a main X-axis (4) is provided on the movable end of the main Z-axis (3), and a main tool assembly (5) is provided on the movable end of the main X-axis (4); The secondary spindle (6) has a secondary Z-axis (7) fixed on the inclined plane on one side, a secondary X-axis (8) is provided on the movable end of the secondary Z-axis (7), and a secondary tool assembly (9) is provided on the movable end of the secondary X-axis (8). The main tool assembly (5) and the auxiliary tool assembly (9) are diagonally distributed.

2. The inclined rail type dual-spindle dual-turret turning and milling composite machining center according to claim 1, characterized in that: The spindle (2) includes a spindle box (21) fixed on an inclined plane. The spindle box (21) is equipped with a spindle assembly (22). The spindle assembly (22) is driven by a servo motor located at the end of the spindle box (21) via a pulley group. The spindle box (21) is equipped with a brake assembly (24) for braking the spindle assembly (22).

3. The inclined rail type dual-spindle dual-turret turning and milling composite machining center according to claim 1, characterized in that: The main tool assembly (5) includes a turret box (51), the output end of which is provided with a tool disc (52), and the input end of the turret box (51) is provided with a turret power motor mounting base (55) for fixing the turret power motor.

4. The inclined rail type dual-spindle dual-turret turning and milling composite machining center according to claim 3, characterized in that: A Y-axis (53) is also provided between the main tool assembly (5) and the main X-axis (4). The Y-axis (53) is fixed on the output end of the main X-axis (4), and the turret box (51) is fixedly connected to the output end of the Y-axis (53).

5. The inclined rail type dual-spindle dual-turret turning and milling composite machining center according to claim 4, characterized in that: The auxiliary tool assembly (9) has the same structure as the main tool assembly (5).

6. The inclined rail type dual-spindle dual-turret turning and milling composite machining center according to claim 1, characterized in that: The secondary spindle (6) includes a secondary spindle box (61) fixed on an inclined plane. The secondary spindle box (61) is equipped with a secondary spindle assembly (62). The input end of the secondary spindle box (61) is equipped with a secondary spindle motor (63) for driving the secondary spindle assembly (62). The secondary spindle motor (63) and the secondary spindle assembly (62) are driven by a pulley set.

7. A control method, characterized in that: The control method, applied to the slant-rail type dual-spindle dual-turret turning-milling composite machining center according to any one of claims 1 to 6, includes the following steps: S1: Obtain the workpiece data to be processed and import the workpiece data into the CNC numerical control system; S2: The CNC numerical control system plans the collaborative machining path of the main tool assembly (5) and the auxiliary tool assembly (9) based on the workpiece data; S3: Clamp the workpiece between the main spindle (2) and the secondary spindle (6) so that the clamping end of the main spindle (2) and the clamping end of the secondary spindle (6) together fix the two ends of the workpiece; S4: Start the main spindle (2) and the auxiliary spindle (6) and control them to rotate synchronously at the same speed; S5: According to the cooperative machining path, control the main tool assembly (5) and the auxiliary tool assembly (9) to machine the rotating workpiece; wherein, the cooperative machining path is planned as follows: The cutting tools on the main cutting tool assembly (5) and the cutting tools on the auxiliary cutting tool assembly (9) are located at the same radial position on the workpiece during machining. The main Z-axis (3) and the auxiliary Z-axis (7) are controlled to feed along the axis of the workpiece, and their feed directions are opposite and their feed speeds are synchronized. The main X-axis (4) and the secondary X-axis (8) are controlled to feed in a direction perpendicular to the axis of the workpiece, and their feed directions are opposite, so that the machining trajectory of the tool on the main tool assembly (5) and the machining trajectory of the tool on the secondary tool assembly (9) are tangent or coincident at the same radial position of the workpiece.

8. The control method according to claim 7, characterized in that: In step S5, the CNC system performs synchronous interpolation control on the main Z-axis (3), main X-axis (4), secondary Z-axis (7), and secondary X-axis (8). Specifically, the CNC system generates a unified interpolation command based on the collaborative machining path. This interpolation command simultaneously drives the servo motors of the main Z-axis (3) and the secondary Z-axis (7) to run at speeds of equal magnitude and opposite directions, and simultaneously drives the servo motors of the main X-axis (4) and the secondary X-axis (8) to run at speeds of equal magnitude and opposite directions, thereby enabling the tools on the main tool assembly (5) and the secondary tool assembly (9) to perform symmetrical cutting on the workpiece along the planned trajectory.

9. The control method according to claim 7 or 8, characterized in that: The method also includes the step of transferring and relaying the workpiece after processing one end of the workpiece: S6: The main spindle (2) and the sub-main spindle (6) stop rotating; S7: The main tool assembly (5) and the auxiliary tool assembly (9) are returned to the safe position; S8: The sub-spindle (6) holds the workpiece and moves it axially away from the spindle (2) so that the workpiece is released from the clamping end of the spindle (2); S9: After the sub-spindle (6) drives the workpiece to rotate to a predetermined angle, the sub-spindle (6) moves along the axial direction to send the processed section of the workpiece into the processing range of the sub-tool assembly (9), while positioning the unprocessed section of the workpiece within the processing range of the main tool assembly (5). S10: Repeat steps S4 to S5, where the main tool assembly (5) processes the unprocessed section of the workpiece, while the auxiliary tool assembly (9) performs a new processing operation on the processed section of the workpiece.

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