A new horizontal numerical control machine tool and a method for improving machining precision thereof

Abstract

The application relates to a novel horizontal numerical control machine tool and a method for improving machining precision of the machine tool, which comprises a base unit (1), a cross beam (3) and a stand (6) installed on the base unit (1), left and right stands (6) are respectively arranged on the left and right sides of the base unit (1), the cross beam (3) is installed on the rear side of the base unit (1) through a cross beam support, a left rotating workbench (7) capable of moving up and down is installed on the right side vertical surface of the left stand, a right rotating workbench capable of moving up and down is also installed on the left side vertical surface of the right stand, left and right main shaft units (5) capable of moving forward and backward and left and right are respectively arranged on the left and right sides of the cross beam (3), the left main shaft unit (5) and the left rotating workbench (7) cooperate to form a left machining channel, the right main shaft unit (5) and the right rotating workbench (7) cooperate to form a right machining channel, and machining cutters are installed on the left and right main shaft units (5); the method reduces machining errors of the machine tool through steps of establishing a thermal error prediction model, synchronous error control, inhibiting cross beam vibration and feedforward compensation, so that the machining precision of the machine tool is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of CNC machine tools, specifically to a novel horizontal CNC machine tool and a method for improving its machining accuracy. Background Technology

[0002] Currently, horizontal CNC machine tools on the market typically have one spindle per channel and a column-type structure. The spindle moves up and down, while the workpiece moves back and forth or left and right. The column is either fixed or moves in all directions. This type of horizontal CNC machine tool occupies a large area, has heavy moving parts, high inertia, poor dynamic characteristics, and a limited machining area. Summary of the Invention

[0003] This application aims to overcome the technical problems existing in the background art by providing a novel horizontal CNC machine tool. The specific technical solution is as follows:

[0004] A novel horizontal CNC machine tool includes a base unit and a crossbeam and columns mounted on the base unit. The left and right columns are respectively located on the left and right sides of the base unit. The crossbeam is mounted on the rear side of the base unit via a crossbeam bracket. A left rotary table that can move up and down is mounted on the right side of the left column, and a right rotary table that can move up and down is also mounted on the left side of the right column. Left and right spindle units that can move forward and backward and left and right are respectively located on the left and right sides of the crossbeam. The left spindle unit and the left rotary table cooperate to form a left machining channel, and the right spindle unit and the right rotary table cooperate to form a right machining channel. Both the left and right spindle units are equipped with machining tools.

[0005] Furthermore, the left rotary table is mounted on the left lead screw drive seat, and the lead screw mounted on the right side of the left column drives the left lead screw drive seat and the left rotary table to move up and down. The right rotary table is mounted on the right lead screw drive seat, and the lead screw mounted on the left side of the right column drives the right lead screw drive seat and the right rotary table to move up and down.

[0006] Furthermore, two linear guide rails are installed on the upper surface of the crossbeam, which are parallel to each other in the left-right direction. A left slide and a right slide are respectively installed on these two linear guide rails. The upper surfaces of the left slide and the right slide are each provided with two linear guide rails that are parallel to each other in the front-back direction. The drive device of the left spindle unit drives the left spindle unit to move back and forth along the linear guide rail on the left slide. The drive device of the right spindle unit drives the right spindle unit to move back and forth along the linear guide rail on the right slide. The drive device of the left slide drives the left slide and the left spindle unit to move left and right. The drive device of the right slide drives the right slide and the right spindle unit to move left and right. The left slide and the right slide have overlapping strokes on the two linear guide rails that are parallel to each other in the left-right direction.

[0007] Furthermore, linear guide rails are installed on the rear facades of both left and right columns. The left and right tool magazines move up and down on the rear facades of the left and right columns via their respective tool magazine mounting seats. The left and right tool magazines cooperate with the left and right spindle units to change tools.

[0008] Furthermore, a chip discharge port is provided in the middle of the base unit, so that the chips on both sides can be discharged directly from the chip discharge port during workpiece processing.

[0009] Furthermore, linear guide rails are provided on the front facades of both left and right columns, allowing the left and right robotic arms to move up and down on the linear guide rails via their mounting bases.

[0010] Furthermore, during workpiece machining, both the left and right tool magazines move to the top of the left and right columns, away from the machining area; when a tool change is required, the left and right tool magazines move downwards and closer to the left and right spindle units respectively to perform the tool change action, while the left and right rotary tables move downwards respectively.

[0011] This application also provides a method for improving the machining accuracy of a novel horizontal CNC machine tool, comprising the following steps:

[0012] (1) Establishing a thermal displacement prediction model: Temperature sensors are installed at various locations on the machine tool, and the thermal elongation ΔL of the spindle end face is measured using a laser interferometer. Based on the least squares support vector machine, a thermal displacement prediction model is established:

[0013]

[0014] Where, α i β is the coefficient of thermal expansion, and β is the dynamic response factor.

[0015] (2) Synchronization error control: Install grating encoders at the ends of the two spindles to collect the rotational speed and phase difference of the two spindles in real time, and use fuzzy PID and feedforward compensation algorithms to dynamically adjust the torque output of the two spindles.

[0016] The synchronization error is: e(t) = θ1 - θ2 - θ ref (t), where θ1 and θ2 represent the actual rotation angles of the two principal axes, θ ref This represents the theoretical synchronization angle difference.

[0017] The cutting force disturbance F is estimated using an observer. dist (t), generating the feedforward compensation amount:

[0018]

[0019] K p K i K d K is a parameter of the PID controller. f u(t) is a constant, and u(t) is the feedforward compensation amount of the main axis;

[0020] (3) Active suppression of beam vibration: Accelerometers and electromagnetic active dampers are arranged on both sides of the beam. Based on the LMS algorithm, an anti-phase vibration signal is generated and a counteracting force is applied through the electromagnetic active damper.

[0021] (4) Feedforward compensation: The predicted thermal deformation is converted into the position offset of each spindle through the feedforward compensation actuator. The torque feedforward compensation of each spindle is input into the CNC system to correct the G-code coordinates in real time.

[0022] Furthermore, installing temperature sensors in various parts of the machine tool specifically refers to installing temperature sensors on the spindle bearing, ball screw nut, column guide rail, and motor housing.

[0023] Furthermore, the active method for suppressing beam vibration in step (3) includes the following steps:

[0024] (31) Collect vibration signals and reference signals of the crossbeam:

[0025] Accelerometers are placed on both sides of the crossbeam to collect the vibration signal of the crossbeam; the signal that is strongly related to the vibration source (spindle speed n(t), feed axis position x(t), cutting force Fc(T)) is selected as the reference signal r(n);

[0026] (32) Transfer function modeling: The frequency response function H(w) of the beam is obtained using experimental modal analysis, and a vibration transfer model is established:

[0027]

[0028] X(w) = H(w)·F(w)

[0029] Where, S xy (w) represents the cross-power spectrum of the input force and the output response, S xx (w) is the self-power spectrum of the input force, X(w) is the vibration displacement of the beam, and F(w) is the excitation force;

[0030] (33) Feedforward controller design:

[0031] The adaptive filter weights W are trained using historical data to minimize the residual vibration energy ∑z(t). 2 ;

[0032] Real-time acquisition of r(t) and actual vibration signal z(t), and dynamic updating of W to adapt to changes in operating conditions:

[0033] W(N+1)=W(N)+μ·z(n)·r(n)

[0034] Where μ is the convergence factor;

[0035] (34) Calculate the compensation force

[0036] Calculate the compensation force Y(t) based on the current reference signal r(t) and the filter weights W:

[0037] Y(t) = W T ·r(t)

[0038] Vibration is counteracted by applying a compensating force Y(t) through an electromagnetic active damper. The electromagnetic active damper can be a piezoelectric ceramic actuator.

[0039] The beneficial technical effects of this application are as follows:

[0040] 1) This application discloses a novel horizontal CNC machine tool with two independent channels. The spindle is directly supported on the crossbeam, resulting in better force distribution. The slides and spindle units of the two channels can be designed to be lighter and more compact. Under the condition of dual-channel processing, the overlap stroke of the left and right movement of the two slides is greatly reduced, and the overall size of the machine tool is greatly reduced.

[0041] 2) The dual channels of the novel horizontal CNC machine tool of this application operate independently without interference. The up-and-down movement of the rotating worktable makes it easier to flip the product, and the chip removal during the processing is better, and the accumulated chips are less likely to scratch the product.

[0042] 3) The novel horizontal CNC machine tool of this application has a funnel-shaped chip discharge port in the center of the base, so that the chips fall directly and the chip removal effect is better than that of ordinary machine tools.

[0043] 4) This application discloses a novel horizontal CNC machine tool, in which guide rail mounting surfaces are provided on three sides of the column, and a rotary worktable is installed in the middle, which moves up and down as the Y-axis; one side is used to install the tool magazine, and the other side is reserved as the mounting position for the loading and unloading robot. In addition, the tool magazine adopts a vertically movable structure, which can be raised up and away from the machining area during machining. During machining, the tool magazine is separated from the machining area, which makes it less likely for chips to enter and provides better protection. The vertical space arrangement does not occupy the front, back, left and right space, making the structure more compact and the machine tool occupying less floor space and more economical. Attached Figure Description

[0044] Figure 1 This is a perspective view of a novel horizontal CNC machine tool according to this application;

[0045] Figure 2 This is a top view of a novel horizontal CNC machine tool according to this application;

[0046] Figure 3 This is a side view of a novel horizontal CNC machine tool according to this application;

[0047] Figure 4 This is a schematic diagram of tool changing for a novel horizontal CNC machine tool according to this application. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 1-4 The present invention will now be described in further detail. It should be understood that the specific details described herein are merely illustrative and are not intended to limit the scope of the invention.

[0049] from Figure 1 As can be seen, this application provides a novel horizontal CNC machine tool, including a base unit 1 and a crossbeam 3 and a column 6 mounted on the base unit 1. The left and right columns 6 are respectively located on the left and right sides of the base unit 1. The crossbeam 3 is mounted on the rear side of the base unit 1 through a crossbeam bracket. A left rotary table 7 that can move up and down is mounted on the right side of the left column, and a right rotary table that can move up and down is also mounted on the left side of the right column. Left and right spindle units 5 that can move forward and backward and left and right are respectively located on the left and right sides of the crossbeam 3. The left spindle unit 5 and the left rotary table 7 cooperate to form a left machining channel, and the right spindle unit 5 and the right rotary table 7 cooperate to form a right machining channel. Both the left and right spindle units 5 are equipped with machining tools.

[0050] Furthermore, the left rotary table 7 is mounted on the left lead screw drive seat 9, and the lead screw 11 mounted on the right side of the left column 6 drives the left lead screw drive seat 9 and the left rotary table 7 to move up and down. The right rotary table 7 is mounted on the right lead screw drive seat 9, and the lead screw 11 mounted on the left side of the right column 6 drives the right lead screw drive seat 9 and the right rotary table 7 to move up and down.

[0051] Furthermore, two linear guide rails are installed on the upper surface of the crossbeam 3, which are arranged parallel to each other in the left-right direction. A left slide and a right slide are respectively installed on these two linear guide rails. The upper surfaces of the left slide and the right slide are each provided with two linear guide rails arranged parallel to each other in the front-back direction. The drive device of the left spindle unit 5 drives the left spindle unit to move back and forth along the linear guide rail on the left slide. The drive device of the right spindle unit 5 drives the right spindle unit to move back and forth along the linear guide rail on the right slide. The drive device of the left slide drives the left slide and the left spindle unit 5 to move left and right. The drive device of the right slide drives the right slide and the right spindle unit 5 to move left and right. The left slide and the right slide have overlapping strokes on the two linear guide rails arranged parallel to each other in the left-right direction.

[0052] Furthermore, linear guide rails are installed on the rear facades of both left and right columns. The left and right tool magazines move up and down on the rear facades of the left and right columns via their respective tool magazine mounting seats. The left and right tool magazines cooperate with the left and right spindle units to change tools.

[0053] Furthermore, a chip discharge port is provided in the middle of the base unit 1, so that the chips on the left and right sides can be directly discharged from the chip discharge port during workpiece processing.

[0054] Furthermore, linear guide rails are provided on the front facades of both left and right columns, allowing the left and right robotic arms to move up and down on the linear guide rails via their mounting bases.

[0055] Furthermore, during workpiece machining, both the left and right tool magazines move to the top of the left and right columns, away from the machining area; when a tool change is required, the left and right tool magazines move downwards and closer to the left and right spindle units respectively to perform the tool change action, while the left and right rotary tables move downwards respectively.

[0056] This application also provides a method for improving the machining accuracy of a novel horizontal CNC machine tool, comprising the following steps:

[0057] (1) Establishing a thermal error prediction model: Temperature sensors are installed at various locations on the machine tool, and the thermal elongation ΔL of the spindle end face is dynamically measured using a laser tracker. Based on the least squares support vector machine, a thermal error prediction model is established:

[0058]

[0059] Where, α i T is the coefficient of thermal expansion. i The values ​​measured by each temperature sensor are T0, where T0 is the initial temperature at various points on the machine tool, and β is the dynamic response factor.

[0060] (2) Synchronization error control: Install grating encoders at the ends of the two spindles of the machine tool to collect the rotation speed and phase difference of the two spindles in real time, and use fuzzy PID and feedforward compensation algorithms to dynamically adjust the torque output of the two spindles;

[0061] The synchronization error is: e(t) = θ1 - θ2 - θ ref (t), where θ1 and θ2 represent the actual rotation angles of the two principal axes, θ ref This represents the theoretical synchronization angle difference.

[0062] The cutting force disturbance F is estimated using an observer. dist (t), generating the feedforward compensation amount:

[0063]

[0064] K p K i K d K is a parameter of the PID controller. f u(t) is a constant, and u(t) is the feedforward compensation amount of the main axis;

[0065] (3) Active suppression of beam vibration: Accelerometers and electromagnetic active dampers are arranged on both sides of the beam. Based on the LMS algorithm, an anti-phase vibration signal is generated and a counteracting force is applied through the electromagnetic active damper.

[0066] (4) Feedforward compensation: The predicted thermal deformation is converted into the position offset of each spindle through the feedforward compensation actuator. The torque feedforward compensation of each spindle is input into the CNC system to correct the G-code coordinates in real time.

[0067] Furthermore, installing temperature sensors in various parts of the machine tool specifically refers to installing temperature sensors on the spindle bearing, ball screw nut, column guide rail, and motor housing.

[0068] Furthermore, the active method for suppressing beam vibration in step (3) includes the following steps:

[0069] (31) Collect vibration signals and reference signals of the crossbeam:

[0070] An accelerometer is placed on the crossbeam to collect the vibration signal of the crossbeam; the signal that is strongly related to the vibration source (spindle speed n(t), feed axis position x(t), cutting force Fc(T)) is selected as the reference signal r(n);

[0071] (33) Transfer function modeling: The frequency response function H(w) of the beam is obtained using experimental modal analysis, and a vibration transfer model is established:

[0072]

[0073] X(w) = H(w)·F(w)

[0074] Where, S xy (w) represents the cross-power spectrum of the input force and the output response, S xx (w) is the self-power spectrum of the input force, X(w) is the vibration displacement of the beam, and F(w) is the excitation force;

[0075] (33) Feedforward controller design:

[0076] The adaptive filter weights W are trained using historical data to minimize the residual vibration energy ∑z(t). 2 ;

[0077] Real-time acquisition of r(t) and actual vibration signal z(t), and dynamic updating of W to adapt to changes in operating conditions:

[0078] W(N+1)=W(N)+μ·z(n)·r(n)

[0079] Where μ is the convergence factor;

[0080] (34) Calculate the compensation force

[0081] Calculate the compensation force Y(t) based on the current reference signal r(t) and the filter weights W:

[0082] Y(t) = W T ·r(t)

[0083] The vibration is counteracted by applying a compensating force Y(t) through an electromagnetic active damper. The electromagnetic active damper is a piezoelectric ceramic actuator.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit this application. For those skilled in the art, various modifications and variations of the embodiments of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving the machining accuracy of a novel horizontal CNC machine tool, characterized in that, This new type of horizontal CNC machine tool includes a base unit and a crossbeam and columns mounted on the base unit. The left and right columns are respectively located on the left and right sides of the base unit. The crossbeam is mounted on the rear side of the base unit through a crossbeam bracket. A left rotary table that can move up and down is installed on the right side of the left column, and a right rotary table that can move up and down is also installed on the left side of the right column. Left and right spindle units that can move forward and backward and left and right are respectively located on the left and right sides of the crossbeam. The left spindle unit and the left rotary table cooperate to form a left machining channel, and the right spindle unit and the right rotary table cooperate to form a right machining channel. Both the left and right spindle units are equipped with machining tools. The method includes the following steps: (1) Establish a thermal displacement prediction model: Install temperature sensors at various points on the machine tool and use a laser tracker to measure the thermal expansion of the spindle end face. A thermal displacement prediction model is established based on least squares support vector machine: in, The coefficient of thermal expansion is For dynamic response factors; (2) Synchronization error control: Install grating encoders at the ends of the two spindles to collect the rotation speed and phase difference of the two spindles in real time, and use fuzzy PID and feedforward compensation algorithms to dynamically adjust the torque output of the two spindles; The synchronization error is: e(t) = θ1 - θ2 - θ ref (t), where θ1 and θ2 represent the actual rotation angles of the two principal axes, θ ref This represents the theoretical synchronization angle difference. The cutting force disturbance F is estimated using an observer. dist (t), generating the feedforward compensation amount: K p K i K d For PID parameters, u(t) is a constant, and u(t) is the feedforward compensation amount of the main axis; (3) Suppress beam vibration: Accelerometers and electromagnetic active dampers are installed on both sides of the beam. Anti-phase vibration signals are generated based on the LMS algorithm, and a counteracting force is applied through the electromagnetic active dampers. (4) Feedforward compensation: The predicted thermal displacement is converted into the position offset of each spindle through the feedforward compensation actuator. The torque feedforward compensation of each spindle is input into the CNC system to correct the G-code coordinates in real time.

2. The method for improving the machining accuracy of a novel horizontal CNC machine tool according to claim 1, characterized in that, The left rotary table is mounted on the left lead screw drive seat. The lead screw mounted on the right side of the left column drives the left lead screw drive seat and the left rotary table to move up and down. The right rotary table is mounted on the right lead screw drive seat. The lead screw mounted on the left side of the right column drives the right lead screw drive seat and the right rotary table to move up and down.

3. The method for improving the machining accuracy of a novel horizontal CNC machine tool according to claim 1, characterized in that, Two linear guides are mounted on the upper surface of the crossbeam, arranged parallel to each other in the left-right direction. A left slide and a right slide are mounted on these two linear guides respectively. The upper surfaces of the left and right slides are each equipped with two linear guides arranged parallel to each other in the front-back direction. The drive unit of the left spindle unit drives the left spindle unit to move back and forth along the linear guide on the left slide. The drive unit of the right spindle unit drives the right spindle unit to move back and forth along the linear guide on the right slide. The drive unit of the left slide drives the left slide and the left spindle unit to move left and right. The drive unit of the right slide drives the right slide and the right spindle unit to move left and right. The left and right slides have overlapping strokes on the two linear guides arranged parallel to each other in the left-right direction.

4. The method for improving the machining accuracy of a novel horizontal CNC machine tool according to claim 1, characterized in that, Linear guide rails are installed on the rear facades of both left and right columns. The left and right tool magazines move up and down on the rear facades of the left and right columns via their respective tool magazine mounting bases. The left and right tool magazines cooperate with the left and right spindle units to change tools.

5. The method for improving the machining accuracy of a novel horizontal CNC machine tool according to claim 1, characterized in that, The base unit has a chip discharge port in the middle, so that the chips on the left and right sides can be discharged directly from the chip discharge port when the workpiece is being processed.

6. The method for improving the machining accuracy of a novel horizontal CNC machine tool according to claim 1, characterized in that, The front facades of both left and right columns are equipped with linear guide rails, allowing the left and right robotic arms to move up and down on the linear guide rails via their mounting bases.

7. A method for improving the machining accuracy of a novel horizontal CNC machine tool according to claim 4, characterized in that, During workpiece machining, both the left and right tool magazines move to the top of the left and right columns, away from the machining area. When a tool change is required, the left and right tool magazines move downwards and closer to the left and right spindle units to perform the tool change action. At the same time, the left and right rotary tables move downwards respectively.

8. A method for improving the machining accuracy of a novel horizontal CNC machine tool according to claim 1, characterized in that, Installing temperature sensors in various parts of the machine tool specifically refers to installing temperature sensors on the spindle bearing, ball screw nut, column guide rail, and motor housing.

9. A method for improving the machining accuracy of a novel horizontal CNC machine tool according to claim 1, characterized in that, The method for suppressing beam vibration in step (3) includes the following steps: (31) Collect vibration signals and reference signals of the crossbeam: Accelerometers are placed on both sides of the crossbeam to collect the vibration signals of the crossbeam; the signal that is strongly correlated with the vibration source is selected as the reference signal r(n); (32) Transfer function modeling: The frequency response function H(w) of the beam is obtained using experimental modal analysis, and a vibration transmission model is established: H(w)= X(w) = H(w)·F(w) in, The cross-power spectrum of the input force and the output response. Let X(w) be the self-power spectrum of the input force, X(w) be the vibration displacement of the beam, and F(w) be the excitation force. (33) Feedforward controller design: The adaptive filter weights W are trained using historical data to minimize residual vibration energy. ; Real-time acquisition of r(t) and actual vibration signal z(t), and dynamic updating of W to adapt to changes in operating conditions: W(N+1)=W(N)+μ·z(n)·r(n) Where μ is the convergence factor; (34) Calculate the compensating force Calculate the compensation force Y(t) based on the current reference signal r(t) and the filter weights W: Y(t)=W T ·r(t) The vibration is counteracted by applying a compensating force Y(t) through an electromagnetic active damper.

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