A thinning processing method and device for rocket tank bottom thin-wall parts

Abstract

The present invention proposes a method and apparatus for thinning thin-walled components of a rocket tank bottom. The thin-walled component is clamped on a fixture, and an inner turning tool and an outer turning tool are respectively positioned on the inner and outer sides of the thin-walled component. The inner turning tool has an inner main cutting edge, and the outer turning tool has an outer main cutting edge. Laser measuring instruments are respectively positioned on the inner and outer sides of the thin-walled component. The method includes: detecting the real-time position and posture of the inner and outer main cutting edges; determining the error between the inner and outer main cutting edges based on the real-time position and posture, as well as the current target cutting position of the thin-walled component; and correcting the position and / or posture of the inner and outer main cutting edges based on the error during the cutting process, so that the inner and outer main cutting edges cut symmetrically on both sides of the thin-walled component. In this way, the position and posture errors of the inner and outer turning tools can be corrected in real time.

Description

Technical Field

[0001] The present invention relates to the field of mechanical processing, and in particular to a method and device for thinning thin-walled parts of a rocket tank bottom. Background Art

[0002] Because the rocket tank bottom is a large, curved, thin-walled component typically made of high-strength aluminum alloy, its machining accuracy directly impacts the overall performance of the rocket. During the thinning process, rough machining typically utilizes traditional single-sided vertical turning, with multiple setups machining the inner and outer surfaces in sequence. Finishing typically involves milling, which involves multiple setups and datum conversions, limiting machining accuracy and efficiency, making it difficult to meet the spacecraft's requirements for lightweight, high precision, and high efficiency. Summary of the Invention

[0003] The present invention aims to at least solve the problems of low efficiency and limited machining accuracy of single-sided turning processes in the prior art.

[0004] In view of this, an object of the present invention is to provide a method for thinning the thin-walled parts of the bottom of a rocket tank.

[0005] Another object of the present invention is to provide a thinning processing device for the thin-walled parts of the bottom of a rocket tank.

[0006] To achieve the above-mentioned objectives, the technical solution of the first aspect of the present invention provides a thinning processing method for a thin-walled part of a rocket tank bottom, wherein the thin-walled part is clamped on a fixture, and an inner turning tool and an outer turning tool are respectively provided on the inner and outer sides of the thin-walled part, the inner turning tool having an inner tool main cutting edge, and the outer turning tool having an outer tool main cutting edge, and a laser measuring instrument is respectively provided on the inner and outer sides of the thin-walled part, and the method comprises:

[0007] The real-time positions and postures of the inner cutter main cutting edge and the outer cutter main cutting edge are detected respectively by the laser measuring instrument;

[0008] determining an error between the inner and outer main cutting edges based on the real-time positions and postures of the inner and outer main cutting edges and a current target cutting position of the thin-walled workpiece, wherein the current target cutting point is determined based on a three-dimensional model of the thin-walled workpiece, and the three-dimensional model of the thin-walled workpiece is determined based on the laser measuring instrument;

[0009] During the cutting process of the inner tool main cutting edge and the outer tool main cutting edge, the position and / or posture of the inner turning tool and the outer turning tool are corrected according to the error so that the inner turning tool and the outer turning tool can cut symmetrically on both sides of the thin-walled part.

[0010] Optionally, the real-time position and posture of the inner tool main cutting edge and the outer tool main cutting edge are determined by:

[0011] Determine the real-time three-dimensional models of the inner turning tool and the outer turning tool according to the laser measuring instrument;

[0012] The real-time positions and postures of the inner tool main cutting edge and the outer tool main cutting edge are determined based on the real-time three-dimensional model.

[0013] Optionally, the error between the inner tool main cutting edge and the outer tool main cutting edge includes a position error between the inner tool main cutting edge and the outer tool main cutting edge and the current target cutting position, and determining the error between the inner tool main cutting edge and the outer tool main cutting edge based on the real-time positions and postures of the inner tool main cutting edge and the outer tool main cutting edge and the current target cutting position of the thin-walled workpiece includes:

[0014] According to the real-time positions of the inner tool main cutting edge and the outer tool main cutting edge, and the current target cutting position, position errors between the inner tool main cutting edge and the outer tool main cutting edge and the current target cutting position are determined.

[0015] Optionally, the error between the inner tool main cutting edge and the outer tool main cutting edge includes an angular error Δθ between the inner tool main cutting edge and the outer tool main cutting edge, and determining the error between the inner tool main cutting edge and the outer tool main cutting edge based on the real-time positions and postures of the inner tool main cutting edge and the outer tool main cutting edge and a current target cutting position of the thin-walled workpiece includes:

[0016] According to the real-time posture of the inner turning tool, the first angle θ between the main cutting edge of the inner tool and the inner surface of the thin-walled part is determined. n ;

[0017] According to the real-time posture of the outer turning tool, the second angle θ between the outer cutting edge of the outer tool and the outer surface of the thin-walled part is determined. w ;

[0018] An angular error Δθ between the inner tool main cutting edge and the outer tool main cutting edge is determined according to the first included angle and the second included angle.

[0019] Optionally, the inner turning tool and the outer turning tool are respectively fixed on corresponding tool execution ends, and the tool execution ends have translational freedom along the X-axis and the Z-axis and rotational freedom around the Y-axis, and the position and / or posture of the inner tool main cutting edge and the outer tool main cutting edge corrected according to the error includes:

[0020] translating the positions of the inner turning tool and the outer turning tool in the X-axis and the Z-axis according to the error to correct the positions of the inner tool main cutting edge and the outer tool main cutting edge;

[0021] The inner turning tool and the outer turning tool are rotated around the Y axis according to the error to correct the postures of the inner tool main cutting edge and the outer tool main cutting edge.

[0022] The tool holders of the inner turning tool and the outer turning tool are both provided with thickness monitoring devices, and the thickness monitoring devices are used to monitor the thickness of the thin-walled workpiece. After correcting the positions and / or postures of the inner turning tool and the outer turning tool according to the error so that the inner tool main cutting edge and the outer tool main cutting edge cut symmetrically on both sides of the thin-walled workpiece, the method further includes:

[0023] Determining the current cutting depths of the inner tool main cutting edge and the outer tool main cutting edge according to the real-time monitored thickness of the thin-walled part;

[0024] When the current cutting depths of the inner tool main cutting edge and the outer tool main cutting edge are inconsistent, the cutting depths of the inner tool main cutting edge and / or the outer tool main cutting edge are adjusted.

[0025] Optionally, it also includes:

[0026] Determining a real-time angle between the inner tool main cutting edge, the outer tool main cutting edge, and the normal line at the current target cutting position;

[0027] When the real-time angle exceeds a preset range, the postures of the inner tool main cutting edge and the outer tool main cutting edge are corrected so that the real-time angle is within the preset range.

[0028] Optionally, the fixture is provided with a pneumatic damping support device for supporting the thin-walled part, and the method further comprises:

[0029] The supporting force of the pneumatic damping support device on the thin-walled part is adjusted according to the cutting conditions of the inner tool main cutting edge and the outer tool main cutting edge.

[0030] The technical solution of the second aspect of the present invention provides a thinning processing device for a thin-walled part of a rocket tank bottom, comprising:

[0031] processor;

[0032] a memory for storing executable instructions for the processor;

[0033] The processor is configured to load and execute the executable instructions to implement the steps of the method described in the first aspect of the present invention.

[0034] Through the above technical solution, during the double-tool cutting process for hemispherical thin-walled parts, the position error and posture error of the inner turning tool and the outer turning tool can be corrected in real time, so that the inner turning tool and the outer turning tool can cut symmetrically on both sides of the thin-walled part, so that the large curvature thin-walled parts are subjected to more uniform force during processing, thereby reducing deformation during processing.

[0035] Additional aspects and advantages of the invention will become apparent from the description which follows, or may be learned by practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of processing a thin-walled part according to an embodiment of the present invention;

[0037] Figure 2 Schematic diagram of the angles between the main cutting edge of the inner tool and the main cutting edge of the outer tool and the wall surface of the thin-walled workpiece during the thin-walled workpiece cutting process according to one embodiment of the present invention;

[0038] Figure 3 is a schematic diagram of the inner tool main cutting edge tip point, the outer tool main cutting edge tip point, the inner cutting point, and the outer cutting point during the thin-walled workpiece cutting process according to one embodiment of the present invention;

[0039] Figure 4 is a schematic diagram of a coordinate system according to an embodiment of the present invention;

[0040] Figure 5 is a flow chart of a thinning method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0042] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0043] Refer to the following Figures 1 to 5 Some embodiments according to the present invention are described.

[0044] Reference Figures 1 to 4 2 is a hemispherical thin-walled part to be processed (for example, a thin-walled part of a rocket tank bottom), which has an inner wall surface 21 and an outer wall surface 22. 1 is a fixture. 3 is an outer turning tool with an outer main cutting edge 31. 4 is an inner turning tool with an inner main cutting edge 41. 5 and 6 are laser measuring instruments. Figures 1 to 5 An embodiment of the present invention provides a thinning processing method for a thin-walled part at the bottom of a hemispherical rocket tank. The thin-walled part is clamped on a fixture, and an inner turning tool and an outer turning tool are respectively provided on the inner and outer sides of the thin-walled part. The inner turning tool has an inner main cutting edge, and the outer turning tool has an outer main cutting edge. Laser measuring instruments are respectively provided on the inner and outer sides of the thin-walled part. The thinning processing method includes:

[0045] Step S1: using a laser measuring instrument to detect the real-time positions and postures of the inner tool main cutting edge and the outer tool main cutting edge respectively.

[0046] It can be understood that since the interior of the hemispherical thin-walled part is not visible, in order to accurately detect the real-time positions of the inner turning tool and the outer turning tool, in this embodiment, a laser measuring instrument is used to detect the real-time positions and postures of the inner turning tool and the outer turning tool, so that the inner turning tool can be accurately detected when the interior is not visible.

[0047] Step S2, determining the errors between the inner turning tool and the outer turning tool based on the real-time positions and postures of the inner tool main cutting edge and the outer tool main cutting edge, and the current target cutting position of the thin-walled workpiece, wherein the current target cutting position (i.e., the target cutting point) is determined based on the three-dimensional model of the thin-walled workpiece, and the three-dimensional model of the thin-walled workpiece is determined based on a laser measuring instrument.

[0048] For example, after a thin-walled part is clamped, two laser measuring instruments can be used to measure the distance from the laser measuring instruments to various points on the thin-walled part, thereby achieving 3D modeling of the thin-walled part. It is understood that during the cutting process, the cutting point changes in real time, so the current target cutting position is the cutting point at the current moment.

[0049] Step S3, during the cutting process of the inner cutter main cutting edge and the outer cutter main cutting edge, the position and / or posture of the inner cutter main cutting edge and the outer cutter main cutting edge are corrected according to the error, so that the inner cutter main cutting edge and the outer cutter main cutting edge cut symmetrically on both sides of the thin-walled part, that is, the inner cutter main cutting edge and the outer cutter main cutting edge cut symmetrically based on the tangent of the midpoint of the line connecting the two cutting points of the thin-walled part.

[0050] In this way, the errors between the inner and outer main cutting edges can be corrected in real time during the cutting process, so that the force on thin-walled parts with large curvature can be more uniform during the processing, reducing deformation during processing.

[0051] Furthermore, the real-time position and posture of the inner tool main cutting edge and the outer tool main cutting edge are determined by: determining the real-time three-dimensional models of the inner turning tool and the outer turning tool based on the laser measuring instrument; determining the real-time position and posture of the inner tool main cutting edge and the outer tool main cutting edge based on the real-time three-dimensional model.

[0052] For example, the point cloud models of the internal turning tool and the external turning tool can be fitted based on the data from the laser measuring instrument, that is, the real-time three-dimensional models of the internal turning tool and the external turning tool can be obtained, and then the real-time position and posture of the inner tool main cutting edge on the internal turning tool and the outer tool main cutting edge on the external turning tool can be determined based on the real-time three-dimensional model.

[0053] Furthermore, the error between the inner tool main cutting edge and the outer tool main cutting edge includes the position error between the inner tool main cutting edge and the outer tool main cutting edge and the current target cutting position (target cutting point). The above-mentioned determination of the error between the inner turning tool and the outer turning tool based on the real-time position and posture of the inner tool main cutting edge and the outer tool main cutting edge, and the current target cutting position of the thin-walled part includes: determining the position error between the inner tool main cutting edge and the outer tool main cutting edge and the current target cutting position based on the real-time position of the inner tool main cutting edge and the outer tool main cutting edge, and the current target cutting position.

[0054] For example, refer to Figure 3 The inner tool main cutting edge has an inner tool main cutting edge tip, and its position coordinates are shown as (X Tn ,Y Tn ,Z Tn ), the outer tool main cutting edge has an outer tool main cutting edge tip, and its position coordinates are shown as (X Tw ,Y Tw ,Z Tw ), the target cutting point on the inner wall of the thin-walled part is shown as (X Wn ,Y Wn ,Z Wn ), the target cutting point on the outer wall of the thin-walled part is indicated as (X Ww ,Y Ww ,Z Ww ). Thus, based on the above four coordinates, the position error between the inner tool main cutting edge tip and the target cutting point on the inner wall surface of the thin-walled workpiece, as well as the position error between the outer tool main cutting edge tip and the target cutting point on the outer wall surface of the thin-walled workpiece can be determined.

[0055] In this way, after correction, the cutting positions of the inner tool main cutting edge and the outer tool main cutting edge can be made accurate, and the alignment of the inner turning tool and the outer turning tool is also facilitated.

[0056] Furthermore, a thickness monitoring device (for example, an ultrasonic measuring device) is provided on the tool holder of each of the inner turning tool and the outer turning tool. The thickness monitoring device is used to monitor the thickness of the thin-walled workpiece (for example, an ultrasonic wave is transmitted from a transmitter through the thin-walled workpiece and returned to a receiver, and the thickness is calculated by measuring the propagation time difference). After the above-mentioned step of correcting the position and / or posture of the inner turning tool and the outer turning tool according to the error so that the inner tool main cutting edge and the outer tool main cutting edge cut symmetrically on both sides of the thin-walled workpiece, the processing method may further include:

[0057] The current cutting depths of the inner and outer main cutting edges are determined based on the real-time monitored thickness of the thin-walled workpiece. For example, the current cutting depths of the inner and outer main cutting edges can be determined based on the real-time monitored changes in wall thickness, and the cutting depths of the inner and outer main cutting edges can then be compared.

[0058] When the current cutting depths of the inner tool main cutting edge and the outer tool main cutting edge are inconsistent, the cutting depths of the inner tool main cutting edge and / or the outer tool main cutting edge are adjusted.

[0059] For example, if the current cutting depth of the inner cutter main cutting edge is too deep, the thickness of the thin-walled part will become thinner, and the cutting depth of the inner cutter main cutting edge can be adjusted to be shallower. Alternatively, if the current cutting depth of the inner cutter main cutting edge is too shallow, the thickness of the thin-walled part will become thicker, and the cutting depth of the inner cutter main cutting edge can be adjusted to be deeper. Similarly, the cutting depth of the outer cutter main cutting edge can be adjusted, which will not be described here. Of course, if the cutting depths of the inner cutter main cutting edge and the outer cutter main cutting edge change at the same time, the thickness of the thin-walled part may not change. In this case, the cutting depths of the inner cutter main cutting edge and the outer cutter main cutting edge still need to be adjusted to make the cutting depths of the inner cutter main cutting edge and the outer cutter main cutting edge consistent.

[0060] Through the scheme of this embodiment, on the basis of adjusting the position and posture of the inner tool main cutting edge and the outer tool main cutting edge, the cutting depth is compensated by monitoring the thickness of the thin-walled workpiece, thereby preventing processing errors caused by errors in adjusting the position and posture of the inner tool main cutting edge and the outer tool main cutting edge, thereby improving processing accuracy.

[0061] Further, refer to Figure 2 The error between the inner and outer main cutting edges includes the angular error of the inner and outer main cutting edges. The error between the inner and outer main cutting edges is determined based on their real-time positions and postures, as well as the current target cutting position of the thin-walled workpiece. The error includes:

[0062] According to the real-time posture of the internal turning tool, the first angle θ between the main cutting edge of the internal tool and the inner surface of the thin-walled workpiece is determined n ;

[0063] According to the real-time posture of the external turning tool, the second angle θ between the main cutting edge of the external tool and the outer surface of the thin-walled workpiece is determined w ;

[0064] An angular error Δθ between the main cutting edge of the inner tool and the main cutting edge of the outer tool is determined according to the first included angle and the second included angle.

[0065] In this way, after correction, the first turning tool and the second turning tool can be made symmetrical based on the tangent line passing through the midpoint of the line connecting the two cutting points of the thin-walled workpiece to balance the forces on both sides of the thin-walled workpiece.

[0066] Furthermore, the inner turning tool and the outer turning tool are respectively fixed on the corresponding tool execution end, and the tool execution end has the translational freedom along the X-axis and the Z-axis and the rotational freedom around the Y-axis. The above-mentioned correction of the position and / or posture of the inner tool main cutting edge and the outer tool main cutting edge according to the error includes: translating the position of the inner turning tool and the outer turning tool in the X-axis and the Z-axis according to the error to correct the position of the inner tool main cutting edge and the outer tool main cutting edge; rotating the inner turning tool and the outer turning tool around the Y-axis according to the error to correct the posture of the inner tool main cutting edge and the outer tool main cutting edge.

[0067] Furthermore, it also includes: determining the real-time angle θ between the inner tool main cutting edge and the outer tool main cutting edge and the normal line at the current target cutting position n and θ w ; When the real-time angle exceeds the preset range, the postures of the inner turning tool and the outer turning tool are corrected so that the real-time angle is within the preset range.

[0068] For example, the preset range may be 0 to 20° to minimize the normal force component and reduce the deformation of the workpiece.

[0069] Furthermore, a pneumatic damping support device for supporting the thin-walled workpiece is provided on the fixture, and the method also includes: adjusting the supporting force of the pneumatic damping support device on the thin-walled workpiece according to the cutting conditions of the internal turning tool and the external turning tool to increase the stability of the workpiece. Specific embodiments

[0071] Reference Figure 1 In a specific embodiment of the present invention, the thinning method includes:

[0072] Step S21: Clamp a thin-walled part of a rocket tank bottom with a large curvature and a diameter of 5 mm and a thickness of 7 mm (hereinafter referred to as the "workpiece" or "thin-walled part") onto a precision fixture of a CNC lathe, ensuring that the workpiece position is stable and the center of the workpiece and the center of the fixture's rotating spindle are on the same axis;

[0073] Optionally, a pneumatic damping auxiliary support device is installed on the fixture. The auxiliary support has good surface adaptability. The control system controls the electromagnetic proportional valve through PID mode. Adjusting the air pressure can ensure that the auxiliary support provides a constant supporting force during the following process, thereby increasing the stability of the workpiece.

[0074] Step S22: The internal and external turning tools are mounted on custom machine tool turrets, one for machining the inner surface of the box bottom and the other for machining the outer surface. The internal and external turning tools have identical geometric parameters, such as rake and relief angles. The toolholder's end-point pre-adjusts the tool positions so that the internal and external turning tools are symmetrically positioned, with their cutting edges aligned with the machining area of ​​the box bottom. The toolholder's end-point control controls both tools to have translational freedom along the X and Z axes and rotational freedom about the Y axis. X-axis motion controls the tool's movement along the thickness of the thin-walled part, controlling the cutting depth of the inner and outer turning tools. Z-axis motion controls the tool's positioning relative to the workpiece, allowing the inner and outer turning tools to complete the workpiece at different positions. Rotational motion around the Y-axis controls the outer turning tool's movement along the surface of the thin-walled part during machining, with the main cutting edge adjusting its angle in real time. The inner and outer main cutting edges of the inner and outer turning tools are both parallel to the normal of the thin-walled part's cutting point, and the inner and outer turning tools are mirror-symmetric along the tangent line of the current cutting point. The tilt angles of the inner and outer main cutting edges need to be continuously adjusted during machining. This degree of freedom allows the inner and outer turning tools to rotate around a specific axis, allowing them to maintain the appropriate cutting angle and tool tip contact position.

[0075] Step S23: Tool setting is performed using two laser measuring instruments; the laser measuring instruments mainly include: a laser transmitter, a laser receiver, a photoelectric sensor, a control system, and a data processing unit. Laser transmitter: generates a high-precision laser beam to detect the position and geometry of the internal and external turning tools. Laser receiver: receives the laser beam that has changed after passing through the internal and external turning tools, and is used to measure parameters such as the position, radius, and angle of the internal and external turning tools. Photoelectric sensor: detects the interaction between the internal and external turning tools and the laser beam, and accurately records the passing time and position changes of the internal and external turning tools. Control system: manages and controls the operation of the laser tool setting instrument, including laser emission, receiving signal processing, and communication with the machine tool control system. Data processing unit: converts the sensor signal into readable data, displays information such as the deviation angle and blade position of the internal and external turning tools, and helps the operator calibrate and compensate the tools.

[0076] Step S231: The workpiece sphere center and the workpiece sphere center along the thin wall symmetrical point are the coordinate origins, and a high-precision laser measuring instrument with two laser transmitters is installed at the two origin positions. First, the time of flight method is used to obtain the distance from the laser measuring instrument position to each measuring point on the inner and outer surfaces of the rocket box bottom.

[0077]

[0078] Where R is the distance of the object measured by the laser measuring instrument, c is the speed of light, and t is the total time of laser flight

[0079] Step S232: Based on the distance RW obtained by the laser measuring instrument, as well as the measured horizontal angle (αW) and vertical angle (βW), the data of each point is converted into rectangular coordinates (X, Y, Z) according to the polar coordinate conversion formula.

[0080]

[0081] Where, (X wn ,Y wn ,Z wn ) is the rectangular coordinate of the point cloud on the inner surface of the thin-walled part, R wn is the distance between the measured inner surface point cloud and the inner laser measuring instrument, β wn is the vertical angle between the inner surface point cloud of the thin-walled part and the inner measuring instrument, α wn is the horizontal angle between the inner surface point cloud of the thin-walled part and the inner measuring instrument, (X ww ,Y ww ,Z ww ) is the rectangular coordinate of the point cloud on the outer surface of the thin-walled part, R ww is the distance between the measured outer surface point cloud and the outer laser measuring instrument, β ww is the vertical angle between the point cloud of the outer surface of the thin-walled part and the external measuring instrument, α ww The horizontal angle between the point cloud of the outer surface of the thin-walled part and the external measuring instrument. The rectangular coordinates of a large number of points are fitted through MATLAB to generate a 3D model of the workpiece with accurate coordinates.

[0082] Step S233: Fitting the tool point cloud model. Similarly, a laser measuring instrument is used to scan the outer surfaces of the inner turning tool and the outer turning tool respectively to generate an inner turning tool 3D model and an outer turning tool 3D model with accurate coordinates.

[0083]

[0084] Where, (X Tn ,Y Tn ,Z Tn ) is the rectangular coordinate of the point cloud of the inner turning tool surface, R Tn is the distance between the measured internal turning tool point cloud and the internal laser measuring instrument, β Tn is the vertical angle between the internal turning tool point cloud and the internal measuring instrument, α Tn is the horizontal angle between the internal turning tool point cloud and the internal measuring instrument, (X Tw ,Y Tw ,Z Tw ) is the rectangular coordinate of the external turning tool point cloud, R Tw is the distance between the measured external turning tool point cloud and the external laser measuring instrument, β Tw is the vertical angle between the external turning tool point cloud and the external measuring instrument, α Tw The horizontal angle between the external turning tool point cloud and the external measuring instrument

[0085] Step S234: Calculate the position error. Based on these position coordinates, the position error between the inner cutting edge of the inner turning tool and the cutting point on the inner wall of the thin-walled workpiece, and the position error between the outer cutting edge of the outer turning tool and the cutting point on the outer wall of the thin-walled workpiece can be obtained:

[0086]

[0087] Where ΔX n ΔY is the position error in the X direction between the cutting edge of the inner turning tool and the cutting point of the inner thin-walled workpiece, n ΔZ is the position error in the Y direction between the cutting edge of the inner turning tool and the cutting point of the inner thin-walled workpiece, n ΔX is the Z-direction position error between the inner turning tool cutting edge and the inner thin-walled workpiece cutting point, w is the position error in the X direction between the cutting edge of the external turning tool and the cutting point of the external thin-walled workpiece, ΔY w is the position error in the Y direction between the cutting edge of the external turning tool and the cutting point of the external thin-walled workpiece, ΔZ w It is the Z-direction position error between the cutting edge of the external turning tool and the cutting point of the external thin-walled workpiece.

[0088] The position error between the inner and outer tools is:

[0089]

[0090] Where ΔX T is the position error between the inner turning tool and the outer turning tool in the X direction, ΔY T is the position error in the Y direction between the inner turning tool and the outer turning tool, ΔZ T It is the Z-direction position error between the inner turning tool and the outer turning tool.

[0091] Step S235: Calculate the angle error. The cutting points of the inner and outer walls of the thin-walled workpiece are P and n (X wn , Y wn , Z wn ), P w (X ww , Y ww , Z ww ), the coordinates of the workpiece center are O(X0, Y0, Z0). Then the normal vectors of the inner and outer wall cutting points of the arc-shaped thin-walled workpiece are for

[0092]

[0093] Among them, the coordinates of the two points on the main cutting edge of the inner tool are P1(X n1 , Y n1 , Z n1 )、P2(X n2 , Y n2 , Z n2), the coordinates of the two points on the main cutting edge of the external tool are P1(X w1 , Y w1 , Z w1 )、P1(X w2 , Y w2 , Z w2 ). The cutting vectors of the internal turning tool and the external turning tool are:

[0094]

[0095] α is the angle between the main cutting edge and the cutting direction, and ij is the unit vector.

[0096] The angle between the inner tool and the inner surface of the thin-walled workpiece is:

[0097]

[0098] Similarly, the angle between the external tool and the outer surface of the thin-walled workpiece is:

[0099]

[0100] The angular error between the inner and outer tools is:

[0101] Δθ=θ n -θ w (16)

[0102] Step S236: Based on the measurement results, the CNC system adjusts the positions of the inner and outer turning tools installed at the end of the tool holder so that the inner and outer tools are in a mirror-symmetrical state, ensuring that the tool position parameters and paths are synchronized, and the tool position error can be controlled to within 1μm.

[0103] Step S237: Using data measured by the laser measuring instrument, the tool holder performs end-control to ensure that the inner and outer main cutting edges of the tool maintain a constant angle with the normal direction of the cutting point on the workpiece surface, ensuring that the tool does not overcut or undercut the workpiece. Optionally, to ensure the optimal relative position between the tool and workpiece when turning thin-walled parts with two tools, the angle between the tool cutting direction and the workpiece surface normal should be between 0 and 20 degrees, minimizing the normal force component and reducing workpiece deformation.

[0104] Step S24: Double-tool turning is used to process the bottom of the rocket tank to obtain the desired workpiece.

[0105] Compared to other rocket tank bottom machining methods, dual-tool turning significantly reduces workpiece deformation during machining, resulting in higher-quality parts. The system controls two tools, using identical cutting parameters and symmetrical tool angles, to simultaneously turn the inner and outer surfaces of the rocket tank bottom. During machining, a laser measuring instrument monitors tool position in real time. If any deviation due to tool vibration is detected, the system automatically compensates to ensure symmetry between the inner and outer turning tools relative to the thin wall.

[0106] by Figures 1 to 4 Taking the machining setup shown in the figure as an example, a method for thinning a rocket tank bottom by turning a thin-walled component using a double-tool turning tool is used. The rocket tank bottom 2 is mounted on a fixture 1, and the outer turning tool 3 and inner turning tool 4 are mounted on the machine tool turret and pre-adjusted to the required machining positions in preparation for machining. An outer laser measuring instrument 5 and an inner laser measuring instrument 6 respectively emit laser beams, illuminating the outer and inner tool tips, and measuring the initial positions of the two tools relative to the workpiece. The system records the laser reflection information and calculates the tool position error. Based on the calculation results, the CNC system adjusts the position of the double tools to ensure that the inner and outer tools are in a mirror-symmetrical state, ensuring synchronization of the tool position parameters and paths. After tool alignment, the double tools turn the rocket tank bottom 2 from the bottom to the top according to the double-tool turning program set by the machine tool CNC system, ultimately obtaining the desired workpiece.

[0107] Step S25: According to the workpiece material and design requirements, reasonable cutting parameters are set, including cutting speed, feed rate, cutting depth, etc., to ensure processing efficiency and surface quality. During the cutting process, the load of the inner and outer tools is balanced to prevent deformation of the workpiece due to asymmetric cutting;

[0108] Step S26: After the processing is completed, the dimensions of the bottom of the rocket tank are measured to check the processing accuracy and surface roughness of the inner surface.

[0109] An embodiment of the present invention also provides a thinning processing device for thin-walled parts of the bottom of a rocket tank, comprising: a processor; a memory for storing executable instructions of the processor; wherein the processor is configured to load and execute the executable instructions to implement the steps of the method of the above embodiment of the present invention.

[0110] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0111] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0112] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0113] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0114] It should be noted that in the claims, any reference signs placed between parentheses shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claim. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, third etc. does not indicate any order. These words may be interpreted as names.

Claims

1. A thinning processing method for the thin-walled bottom of a hemispherical rocket tank, characterized in that: The thin-walled workpiece is clamped on a fixture, and an inner turning tool and an outer turning tool are respectively provided on the inner and outer sides of the thin-walled workpiece, the inner turning tool having an inner tool main cutting edge, and the outer turning tool having an outer tool main cutting edge, and a laser measuring instrument is respectively provided on the inner and outer sides of the thin-walled workpiece, and the method includes: Step S11, respectively detecting the real-time positions and postures of the inner cutter main cutting edge and the outer cutter main cutting edge by the laser measuring instrument; Step S12, determining an error between the inner and outer main cutting edges based on the real-time positions and postures of the inner and outer main cutting edges and a current target cutting position of the thin-walled workpiece, wherein the current target cutting point is determined based on a three-dimensional model of the thin-walled workpiece, and the three-dimensional model of the thin-walled workpiece is determined based on the laser measuring instrument; Step S13, during the cutting process of the inner tool main cutting edge and the outer tool main cutting edge, the position and / or posture of the inner turning tool and the outer turning tool are corrected according to the error to control the inner tool main cutting edge and the outer tool main cutting edge to synchronously turn the inner and outer surfaces of the bottom of the rocket tank with the same cutting parameters and symmetrical tool angles.

2. The thinning method according to claim 1, characterized in that: The real-time positions and postures of the inner tool main cutting edge and the outer tool main cutting edge are determined by: Determine the real-time three-dimensional models of the inner turning tool and the outer turning tool according to the laser measuring instrument; The real-time positions and postures of the inner tool main cutting edge and the outer tool main cutting edge are determined based on the real-time three-dimensional model.

3. The thinning method according to claim 1, characterized in that: The error between the inner tool main cutting edge and the outer tool main cutting edge includes a position error between the inner tool main cutting edge and the outer tool main cutting edge and the current target cutting position. Step S12 specifically includes: According to the real-time positions of the inner tool main cutting edge and the outer tool main cutting edge, and the current target cutting position, position errors between the inner tool main cutting edge and the outer tool main cutting edge and the current target cutting position are determined.

4. The thinning method according to claim 3, characterized in that: The error between the inner tool main cutting edge and the outer tool main cutting edge includes an angular error between the inner tool main cutting edge and the outer tool main cutting edge. Step S12 specifically includes: Determining a first angle θn between the main cutting edge of the inner turning tool and a tangent plane of the inner surface of the thin-walled workpiece passing through a cutting point according to the real-time posture of the inner turning tool; Determining a second angle θw between the main cutting edge of the external turning tool and a tangent plane of the outer surface of the thin-walled workpiece passing through a cutting point according to the real-time posture of the external turning tool; An angular error Δθ between the inner tool main cutting edge and the outer tool main cutting edge is determined according to the first included angle and the second included angle.

5. The thinning method according to claim 1, characterized in that: The inner turning tool and the outer turning tool are respectively fixed on corresponding tool execution ends, and the tool execution ends have translational freedom along the X axis and the Z axis and rotational freedom around the Y axis. The position and / or posture of the inner tool main cutting edge and the outer tool main cutting edge are corrected according to the error, including: translating the positions of the inner turning tool and the outer turning tool in the X-axis and the Z-axis according to the error to correct the positions of the inner tool main cutting edge and the outer tool main cutting edge; The inner turning tool and the outer turning tool are rotated around the Y axis according to the error to correct the postures of the inner tool main cutting edge and the outer tool main cutting edge.

6. The thinning method according to any one of claims 1 to 5, characterized in that: After correcting the positions and / or postures of the inner turning tool and the outer turning tool according to the error so that the inner tool main cutting edge and the outer tool main cutting edge cut symmetrically on both sides of the thin-walled part, the method further comprises: Determining the current cutting depths of the inner tool main cutting edge and the outer tool main cutting edge according to the real-time monitored thickness of the thin-walled part; When the current cutting depths of the inner tool main cutting edge and the outer tool main cutting edge are inconsistent, the cutting depths of the inner tool main cutting edge and / or the outer tool main cutting edge are adjusted.

7. The thinning method according to any one of claims 1 to 5, characterized in that: Also includes: Determine the real-time angle between the inner tool main cutting edge and the outer tool main cutting edge and the normal at the current target cutting position. When the real-time angle exceeds a preset range, correct the postures of the inner tool main cutting edge and the outer tool main cutting edge so that the real-time angle is within the preset range.

8. The thinning method according to any one of claims 1 to 5, characterized in that: The fixture is provided with a pneumatic damping support device for supporting the thin-walled part, and the method further includes: The supporting force of the pneumatic damping support device on the thin-walled part is adjusted according to the cutting conditions of the inner tool main cutting edge and the outer tool main cutting edge.

9. A thinning processing device, characterized in that: include: processor; a memory for storing executable instructions for the processor; The processor is configured to load and execute the executable instructions to implement the steps of the method according to any one of claims 1 to 8.

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