Boring bar capable of adjusting rigidity of cantilever on line and working method

Abstract

The invention discloses a boring bar capable of adjusting the rigidity of a cantilever online and a working method, and belongs to the technical field of metal cutting machining. A boring rod of the device comprises a floating part and a fixed part, the centers of the floating part and the fixed part are connected through a lead screw, the outer sides of the floating part and the fixed part are assembled in a tooth groove axial opposite insertion mode, an acceleration sensor, a controller, a motor and the lead screw capable of rotating along with an output shaft of the motor are arranged in the floating part, and the acceleration sensor collects real-time vibration signals of the boring rod. The controller analyzes the main frequency of the vibration signal and drives the motor to drive the lead screw to rotate, so that the floating part moves in the axial direction of the boring rod, the overall length of the boring rod is changed, then the inherent frequency of the boring rod is changed, the inherent frequency of the boring rod can be far away from the main frequency of vibration in real time by adjusting the rigidity of the cantilever online, and the purpose of avoiding resonance is achieved. Vibration in part machining is reduced, and the quality of the machined surface is improved.

Description

Technical Field

[0001] The invention relates to a boring bar capable of adjusting cantilever stiffness online and a working method thereof, belonging to the technical field of metal cutting processing. Background Art

[0002] In boring processing, when the boring excitation frequency is close to the main frequency of the boring bar, it is easy to cause the boring bar to resonate, and vibration instability often occurs, affecting the surface quality of the processing. When the cutting material is different and the cutting amount is different, the boring excitation frequency is not the same. The existing boring bar has a fixed structure and size, and it is difficult to adjust the stiffness and main frequency for different excitation frequencies, resulting in poor vibration suppression effect.

[0003] In the prior art, in order to reduce the vibration of the boring bar during the cutting process of the boring tool, a boring bar vibration damper with an annular structure is sleeved on the boring bar. The boring bar vibration damper is a vibration damping disk and is connected to the boring bar through a key. A limit block is provided below the vibration damping disk to stop and limit the vibration damping disk on the boring bar along the axial direction of the boring bar. An annular groove is provided inside the vibration damping disk, and a vibration absorbing layer is provided on the inner wall of the annular groove. When the boring tool performs a boring operation, the vibration absorbing layer can damp the vibration and absorb the vibration buffer, thereby playing a vibration reduction role. However, in the above-mentioned vibration damper for the boring bar, the vibration absorbing layer is provided inside the vibration damping disk. When in use, a corresponding axial limiting structure needs to be provided on the boring bar to ensure the relative fixation of the vibration absorbing layer and the boring bar. The installation is inconvenient and difficult to manufacture. The corresponding fixing structure needs to be processed on the boring bar, and the processing cost is high. Summary of the invention

[0004] Technical problem: In view of the deficiencies in the prior art, the present invention provides a boring bar and a working method capable of adjusting the cantilever stiffness online. The boring bar and the working method have a simple structure and can realize online real-time adjustment of the cantilever stiffness.

[0005] Technical solution: To achieve the above technical purpose, the present invention provides a boring bar capable of adjusting the cantilever stiffness online, comprising a floating part and a fixed part arranged front and rear, the rear end of the floating part and the front end of the fixed part being movably connected through a key tooth structure in the form of axial insertion, an active displacement device being arranged between the floating part and the fixed part, the floating part being able to change its length by telescoping at the end of the fixed part through the active displacement device, thereby changing the vibration frequency during operation;

[0006] The active displacement device includes a screw groove arranged between the floating part and the fixed part, a screw for assisting the extension and retraction of the floating part is arranged in the screw groove, an acceleration sensor, a controller and a motor are arranged in the floating part in sequence, the output shaft of the motor is connected to the screw, and the screw is connected to the fixed part. The motor is controlled by the controller to drive the screw to rotate in the fixed part, thereby changing the length of the screw between the floating part and the fixed part, thereby adjusting the total length of the floating part and the fixed part; the floating part and the fixed part are engaged and connected by a key tooth structure on the outside of the screw groove, and the key tooth structure includes teeth and tooth grooves which are respectively and alternately arranged on the floating part and the fixed part; the teeth and tooth grooves provide the boring bar with anti-torsion force.

[0007] Furthermore, there are four teeth and four tooth grooves between the floating part and the fixed part, and the central angle of each tooth or tooth groove is 45°.

[0008] Furthermore, the fixed part is connected and fixed to the machine tool fixture. When the lead screw rotates with the motor, it drives the floating part to move forward and backward relative to the fixed part, thereby changing the overall length of the boring bar and then changing the natural frequency of the boring bar, effectively reducing resonance.

[0009] Furthermore, a flexible telescopic sleeve is provided on the outside of the key tooth structure between the floating part and the fixed part, thereby ensuring that the key tooth structure between the floating part and the fixed part is covered by the flexible telescopic sleeve when the screw is working within the entire designed telescopic range, preventing debris from entering the screw groove during operation and causing equipment failure.

[0010] A working method of a boring bar capable of adjusting the cantilever stiffness online, in a linear feed condition:

[0011] Fix the fixed part on the machine tool fixture, start the machine tool to make the boring bar perform boring work, at this time, the speed sensor detects the current boring excitation information of the boring bar in real time, and sends the detected boring excitation information to a controller, the controller analyzes the main frequency of the vibration signal and drives the motor to drive the lead screw to rotate, thereby changing the total length of the floating part and the fixed part. Since the cantilever stiffness between the floating part and the fixed part is controlled by the tooth and tooth groove bite distance of the two parts, the cantilever stiffness of the boring bar can be controlled by adjusting the lead screw to change the total length of the floating part and the fixed part; when When the total length of the floating part and the fixed part increases, the length of the engagement between the floating part and the fixed part through the teeth and the tooth grooves decreases, reducing the cantilever stiffness of the boring bar and reducing the current vibration frequency of the boring bar; when the total length of the floating part and the fixed part decreases, the length of the engagement between the floating part and the fixed part through the teeth and the tooth grooves increases, increasing the cantilever stiffness of the boring bar and reducing the operating frequency of the boring bar; during operation, the controller changes the natural frequency of the boring bar according to the current vibration main frequency data detected by the speed sensor, so that the natural frequency of the boring bar is far away from the vibration main frequency, thereby achieving the purpose of avoiding resonance.

[0012] Beneficial effects: The boring bar of the device can adjust the length and stiffness of the cantilever in real time according to different boring excitations, and then control the main frequency of the boring bar to keep it away from the excitation frequency in real time, so as to avoid resonance. The decoupling is simple and easy to use, and it can be quickly and automatically adjusted to achieve shock absorption in working conditions where only linear feed is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic structural diagram of a boring bar capable of adjusting cantilever stiffness online according to the present invention;

[0014] Figure 2 A cross-sectional view of the boring bar capable of adjusting the cantilever stiffness online according to the present invention;

[0015] Figure 3 A schematic structural diagram of a floating portion of a boring bar capable of adjusting cantilever stiffness online according to the present invention.

[0016] In the figure: 1. Floating part; 2. Fixed part; 3. Acceleration sensor; 4. Controller; 5. Motor; 6. Screw. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] like Figure 1 and Figure 2 As shown, the present invention discloses a boring bar capable of adjusting cantilever stiffness online, comprising a floating part 1 and a fixed part 2 arranged front and rear, the rear end of the floating part 1 and the front end of the fixed part 2 being movably connected via a key tooth structure in the form of axial insertion, an active displacement device being arranged between the floating part 1 and the fixed part 2, the floating part 1 being extended and retracted at the end of the fixed part 2 via the active displacement device to change the length, thereby changing the vibration frequency during operation;

[0019] The active displacement device includes a screw groove arranged between the floating part 1 and the fixed part 2, a screw 6 for assisting the floating part 1 in telescopic movement is arranged in the screw groove, an acceleration sensor 3, a controller 4 and a motor 5 are arranged in the floating part 1 in sequence, the output shaft of the motor 5 is connected to the screw 6, the screw 6 is connected to the fixed part 2, the motor 5 is controlled by the controller 4 to drive the screw 6 to rotate in the fixed part 2, thereby changing the length of the screw 6 between the floating part 1 and the fixed part 2, thereby adjusting the total length of the distance between the floating part 1 and the fixed part 2; the floating part 1 and the fixed part 2 are engaged and connected by a key tooth structure on the outside of the screw groove, the key tooth structure includes teeth and tooth grooves arranged alternately on the floating part 1 and the fixed part 2; the anti-torsion force of the boring bar is provided by the teeth and tooth grooves. A flexible telescopic sleeve is arranged on the outside of the key tooth structure between the floating part 1 and the fixed part 2, thereby ensuring that the key tooth structure between the floating part 1 and the fixed part 2 is covered by the flexible telescopic sleeve when the screw 6 works within the entire designed telescopic range, preventing debris from entering the screw groove during work and causing equipment failure.

[0020] like Figure 3 As shown, there are four teeth and four tooth grooves between the floating part 1 and the fixed part 2, and the central angle of each tooth or tooth groove is 45°. The fixed part 2 is connected and fixed to the machine tool fixture. When the lead screw 6 rotates with the motor 5, it drives the floating part 1 to move forward and backward relative to the fixed part 2, thereby changing the overall length of the boring bar and then changing the natural frequency of the boring bar, effectively reducing resonance.

[0021] A working method of a boring bar capable of adjusting the cantilever stiffness online, in a linear feed condition:

[0022] Fix the fixed part 2 on the machine tool fixture, start the machine tool and let the boring bar start boring. At this time, the speed sensor 3 detects the current boring excitation information of the boring bar in real time, and sends the detected boring excitation information to a controller 4. The controller analyzes the main frequency of the vibration signal and drives the motor to drive the screw to rotate to change the total length of the floating part 1 and the fixed part 2. Since the cantilever stiffness between the floating part 1 and the fixed part 2 is controlled by the tooth and tooth groove bite distance of the two parts, the cantilever stiffness of the boring bar can be controlled by adjusting the screw 6 to change the total length of the floating part 1 and the fixed part 2; when the floating part 1 and the fixed part 2 are closer, the cantilever stiffness of the boring bar can be controlled. When the total length of the moving part 1 and the fixed part 2 increases, the length of the engagement between the floating part 1 and the fixed part 2 through the teeth and the tooth grooves is reduced, thereby reducing the cantilever stiffness of the boring bar and reducing the current vibration frequency of the boring bar; when the total length of the floating part 1 and the fixed part 2 is reduced, the length of the engagement between the floating part 1 and the fixed part 2 through the teeth and the tooth grooves is increased, thereby increasing the cantilever stiffness of the boring bar and reducing the operating frequency of the boring bar; during operation, the controller 4 changes the natural frequency of the boring bar according to the current vibration main frequency data detected by the speed sensor 3, so that the natural frequency of the boring bar is far away from the vibration main frequency, thereby achieving the purpose of avoiding resonance.

[0023] It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. All components not specified in this embodiment can be implemented using existing technologies.

Claims

1. A boring bar with online adjustable cantilever stiffness, characterized in that: The invention comprises a floating part (1) and a fixed part (2) arranged front and rear, wherein the rear end of the floating part (1) and the front end of the fixed part (2) are movably connected via a key tooth structure in the form of axial insertion, and an active displacement device is provided between the floating part (1) and the fixed part (2). The floating part (1) is extended and retracted at the end of the fixed part (2) via the active displacement device to change its length, thereby changing the vibration frequency during operation. The active displacement device comprises a screw groove arranged between a floating part (1) and a fixed part (2), a screw (6) for assisting the floating part (1) to extend and retract is arranged in the screw groove, an acceleration sensor (3), a controller (4) and a motor (5) are arranged in the floating part (1) in sequence, an output shaft of the motor (5) is connected to the screw (6), the screw (6) is connected to the fixed part (2), the motor (5) is controlled by the controller (4) to work, thereby driving the screw (6) to rotate in the fixed part (2), thereby changing the length of the screw (6) between the floating part (1) and the fixed part (2), thereby adjusting the total length of the floating part (1) and the fixed part (2); the floating part (1) and the fixed part (2) are engaged and connected by a key tooth structure on the outer side of the screw groove, the key tooth structure comprises teeth and tooth grooves respectively arranged and arranged alternately on the floating part (1) and the fixed part (2); the teeth and tooth grooves provide the anti-torsion force of the boring bar.

2. A boring bar with online adjustable cantilever stiffness according to claim 1, characterized in that: There are four teeth and four tooth grooves between the floating part (1) and the fixed part (2), and the central angle of each tooth or tooth groove is 45 degrees.

3. The boring bar with online adjustable cantilever stiffness according to claim 1, characterized in that: The fixed part (2) is connected and fixed to the machine tool fixture. When the lead screw (6) rotates with the motor (5), it drives the floating part (1) to move forward and backward relative to the fixed part (2), thereby changing the overall length of the boring bar and then changing the natural frequency of the boring bar, effectively reducing resonance.

4. The boring bar with online adjustable cantilever stiffness according to claim 1, characterized in that: A flexible telescopic sleeve is provided on the outside of the key tooth structure between the floating part (1) and the fixed part (2), thereby ensuring that the key tooth structure between the floating part (1) and the fixed part (2) is covered by the flexible telescopic sleeve when the lead screw (6) works within the entire designed telescopic range, thereby preventing debris from entering the lead screw groove during operation and causing equipment failure.

5. A working method using the boring bar with online adjustable cantilever stiffness according to claims 1 to 4, characterized in that: In the case of linear feed: The fixed part (2) is fixed on the machine tool fixture, and the machine tool is started to make the boring bar perform boring work. At this time, the speed sensor (3) detects the current boring excitation information of the boring bar in real time, and sends the detected boring excitation information to a controller (4). The controller analyzes the main frequency of the vibration signal and drives the motor to drive the lead screw to rotate, thereby changing the total length of the floating part (1) and the fixed part (2). Since the cantilever stiffness between the floating part (1) and the fixed part (2) is controlled by the tooth and tooth groove engagement distance of the two parts, the cantilever stiffness of the boring bar can be controlled by adjusting the lead screw (6) to change the total length of the floating part (1) and the fixed part (2); when When the total length of the floating part (1) and the fixed part (2) increases, the length of the engagement between the floating part (1) and the fixed part (2) through the teeth and tooth grooves decreases, thereby reducing the cantilever stiffness of the boring bar and reducing the current vibration frequency of the boring bar; when the total length of the floating part (1) and the fixed part (2) decreases, the length of the engagement between the floating part (1) and the fixed part (2) through the teeth and tooth grooves increases, thereby increasing the cantilever stiffness of the boring bar and reducing the working frequency of the boring bar; during operation, the controller (4) changes the natural frequency of the boring bar according to the current vibration main frequency data detected by the speed sensor (3), so that the natural frequency of the boring bar is far away from the vibration main frequency, thereby achieving the purpose of avoiding resonance.

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