Pneumatic step excitation device for lathe frequency response test

Abstract

The air step excitation device for lathe frequency response test comprises a cylinder for applying excitation force to a simulation workpiece, a two-position five-way manual control valve for controlling the cylinder, and a force sensor, an acceleration sensor and a signal analysis system for obtaining the frequency response characteristics of the lathe; the simulation workpiece is pre-installed on the lathe, the cylinder is fixed on the tool rest of the lathe through a cylinder mounting frame, and the cylinder is communicated with an air source through the two-position five-way manual control valve; the telescopic rod of the cylinder is aligned with the simulation workpiece, the end of the telescopic rod of the cylinder is provided with a piston impact head, the position close to the end of the telescopic rod of the cylinder is provided with the force sensor, and the simulation workpiece is provided with the acceleration sensor; and the force sensor and the acceleration sensor are electrically connected with the signal analysis system. The step excitation force is used to replace the pulse excitation force to realize the wideband excitation of the machine tool structure, the signal generator and the power amplifier of the conventional excitation unit are omitted, the excitation device is simplified, the cost is reduced, and the operation is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to a pneumatic step excitation device for frequency response testing of a lathe. BACKGROUND

[0002] Through the test analysis of the dynamic characteristics of a machine tool, a basis can be provided for improving the dynamic characteristics of the machine tool, so as to achieve the purpose of improving the machining quality and cutting efficiency of the machine tool. The frequency response testing of the machine tool structure is an effective means for analyzing the dynamic characteristics of the machine tool structure.

[0003] The frequency response testing system mainly comprises a testing object, an excitation unit, a vibration testing unit and a frequency response analysis unit. As shown in Figure 1 , the excitation unit generates vibration and acts on the machine tool, the vibration testing unit measures the vibration response of the machine tool, the vibration signal measured by the sensor is transmitted to the frequency response analysis unit, and finally the frequency response of the machine tool is analyzed by the frequency response analysis unit.

[0004] The excitation unit generally comprises a signal generator, a power amplifier and an exciter. As shown in Figure 2 , the signal generator generates the required excitation signal, the power amplifier amplifies the signal and drives the exciter. There are mainly two ways of excitation: absolute excitation and relative excitation.

[0005] When the machine tool is working, the cutting force between the machined workpiece and the tool will eventually act on the machine tool itself. When the frequency response of the machine tool structure is tested, the excitation force is applied between the simulated workpiece and the simulated tool, which can better simulate the stress condition of the actual machining of the machine tool. Therefore, when the frequency response of the machine tool structure is tested, it is often more desirable to excite the machine tool relative to the excitation.

[0006] The excitation device is the core of the excitation unit, and common excitation devices include hydraulic exciter, electromagnetic exciter, pulse hammer, etc. Among them, the hydraulic exciter can obtain a larger excitation force, but the upper limit of the excitation frequency is lower. The structure size and weight of the hydraulic exciter and the electromagnetic exciter are larger, and they can be installed and fixed on the machine tool, and are more suitable for relative excitation of the machine tool structure. When the milling machine, boring machine, machining center and the like are excited, the exciter is often directly installed on the workbench. When the lathe is excited, the exciter can also be installed on the tool holder of the lathe, and the excitation force is applied between the simulated workpiece and the tool holder. However, the structure size of the hydraulic exciter and the electromagnetic exciter is much larger than the installation space, and the installation is difficult. Moreover, due to the relatively large mass of the hydraulic exciter and the electromagnetic exciter, if they are installed on the tool holder, the dynamic structural performance of the machine tool will change due to the large additional mass, which will bring errors to the test results. Although the pulse hammer has the advantages of simple and convenient operation, wide frequency excitation, high test efficiency and the like, the pulse hammer is manually operated, and each time of knocking will inevitably produce some differences, and the repeatability is poor. Moreover, the pulse hammer excitation can only realize the absolute excitation of one point of the simulated workpiece or the simulated tool, and cannot be used for relative excitation of the machine tool structure. SUMMARY

[0007] In order to overcome the above problems, the application provides a pneumatic step excitation device for lathe frequency response test.

[0008] The technical scheme adopted by the application is: a pneumatic step excitation device for lathe frequency response test, comprising a pneumatic cylinder for applying excitation force to a simulated workpiece, a two-position five-way manual control valve for controlling the pneumatic cylinder, and a force sensor, an acceleration sensor and a signal analysis system for obtaining the frequency response characteristics of the lathe.

[0009] The simulated workpiece is pre-installed on the lathe, the pneumatic cylinder is fixed on the tool holder of the lathe through a pneumatic cylinder mounting bracket, and the pneumatic cylinder is communicated with the air source through the two-position five-way manual control valve. The extension rod of the pneumatic cylinder is aligned with the simulated workpiece, the end of the extension rod of the pneumatic cylinder is provided with a piston impact head, the position close to the end of the extension rod of the pneumatic cylinder is provided with a force sensor, and the simulated workpiece is provided with an acceleration sensor. The force sensor and the acceleration sensor are respectively electrically connected with the signal analysis system. The force sensor measures the excitation force generated by the pneumatic cylinder and sends it to the signal analysis system, the acceleration sensor measures the vibration acceleration signal of the simulated workpiece and sends it to the signal analysis system, and the signal analysis system obtains the frequency response characteristics of the lathe according to the received excitation force and vibration acceleration signal.

[0010] Further, the pneumatic cylinder and the simulated workpiece are vertically arranged in a horizontal plane, or the pneumatic cylinder and the simulated workpiece are vertically arranged in a vertical plane, or the axis of the pneumatic cylinder is collinearly arranged with the axis of the simulated workpiece.

[0011] Further, the piston impact head is made of rubber, or nylon, or aluminum alloy, or steel.

[0012] The beneficial effects of the present application are:

[0013] (1) The pneumatic step excitation device is compact in structure, easy to install on the tool holder of a lathe, and the generated step excitation force can directly act between the simulated workpiece and the simulated tool. Moreover, since the excitation force is pneumatically controlled, it has good consistency when repeatedly excited, greatly ensuring the accuracy of the test.

[0014] (2) Compared with electromagnetic excitation, in electromagnetic excitation, a signal generator generates a simple harmonic signal, or a random signal, or other wideband signals, which are amplified by a power amplifier to drive the electromagnetic exciter to generate corresponding simple harmonic excitation force, or random excitation force, or other wideband excitation force. For the pneumatic step excitation device, due to the limitations of pneumatic control, it is difficult to generate simple harmonic excitation force or random excitation force. It needs to be noted that the excitation force applied to the machine tool by pneumatic control is not a pulse form of wideband excitation force like a "pulse hammer", but a step form of wideband excitation force. This patent combines the characteristics of pneumatic control and uses the simplest pneumatic control method to generate step excitation force by pneumatic to realize excitation.

[0015] The waveform of the generated excitation force can be represented by the impulse function δ(t) in theory:

[0016]

[0017] The waveform of the generated excitation force can be represented by the unit step function u(t) in theory:

[0018]

[0019] The derivative of the unit step function u(t)

[0020]

[0021] is the impulse function δ(t), so the wideband excitation force in the form of step signal can also meet the requirements of exciting the machine tool structure. The wideband excitation force in the form of step force signal generated by the pneumatic step excitation device in this invention has similar wideband characteristics as the pulse hammer excitation, and a single excitation can realize excitation in a wide frequency range, with high efficiency of test. The frequency range of the step force signal generated by pneumatic can be adjusted by replacing the material of the piston impact head of the pneumatic step excitation device, such as replacing it with rubber, or nylon, or aluminum alloy, or steel, and the upper limit of the excitation frequency of these materials will increase in order to meet the requirements of different test frequency ranges.

[0022] (3) the present application can realize relative excitation when the lathe, CNC lathe, turning center and the like are tested in frequency response, which solves the problem that the hydraulic exciter and the electromagnetic exciter are not suitable for lathe excitation due to the size and weight, and the pulse hammer excitation cannot realize relative excitation, and the step excitation force is used to replace the pulse excitation force to realize the wideband excitation of the machine tool structure, which saves the "signal generator" and "power amplifier" of the conventional excitation unit, simplifies the excitation device, reduces the cost and is convenient to operate. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of a frequency response test system.

[0024] Figure 2 is a mechanism schematic diagram of the excitation unit.

[0025] Figure 3 is a structural schematic diagram of the present application.

[0026] Figure 4 is a gas circuit diagram of the cylinder in the present application. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described clearly and completely in combination with the drawings, obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

[0028] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" appear only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0029] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms such as "mounting", "connection", "linking" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal connection of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] Referring to the drawings Figures 3-4 The device for aerodynamic step excitation of lathe frequency response test comprises a cylinder 1 for applying excitation force to the simulated workpiece 7, a two-position five-way manual control valve for controlling the cylinder, and a force sensor 2, an acceleration sensor 3 and a signal analysis system 4 for obtaining the frequency response characteristics of the lathe.

[0031] The cylinder 1 is fixed on the lathe tool rest 6 through the cylinder mounting bracket 5, a suitable simulated workpiece 7 is pre-installed on the lathe chuck 8, and the cylinder 1 is aligned with the simulated workpiece 7. The cylinder 1 is communicated with the air source 10 through the two-position five-way manual control valve 9, and the cylinder 1 is controlled by a two-position five-way manual control valve 9, which is simple in structure and convenient to operate. The end of the telescopic rod of the cylinder is provided with a piston impact head, and the force sensor 2 is arranged on the telescopic rod of the cylinder close to the end. The acceleration sensor 3 is arranged on the simulated workpiece 7, and the force sensor 2 and the acceleration sensor 3 are respectively electrically connected with the signal analysis system 4. The force sensor 2 measures the excitation force generated by the cylinder and sends it to the signal analysis system 4, and the acceleration sensor 3 measures the vibration acceleration signal of the simulated workpiece and sends it to the signal analysis system 4. The signal analysis system 4 obtains the frequency response characteristics of the lathe according to the received excitation force and vibration acceleration signal.

[0032] By replacing different cylinder mounting brackets 5, the cylinder 1 can be adjusted to different positions, so as to realize the excitation in the radial horizontal and vertical directions and the axial direction of the simulated workpiece 7, and the frequency response characteristics of the machine tool are obtained by the signal analysis system.

[0033] The frequency range of the step force signal generated by the aerodynamic can be adjusted by replacing the material of the piston impact head of the aerodynamic step excitation device, such as replacing it with rubber, nylon, aluminum alloy or steel, and the upper limit of the excitation frequency of these materials will be sequentially increased to meet the requirements of different test frequency ranges.

[0034] The pneumatic excitation device provided by the scheme solves the problem of lacking ideal exciter for relative excitation of the lathe in the lathe frequency response test. In the lathe frequency response test, the step excitation force is creatively used to replace the pulse excitation force to realize the wide-band excitation of the lathe structure. Finally, the pneumatic step excitation device provided by the scheme can also omit the signal generator and power amplifier of the conventional excitation unit, so that the excitation device is simplified, the cost is reduced, and the operation is facilitated.

[0035] The content described in the embodiments of the present specification is only a list of implementation forms of the inventive concept, and the protection scope of the present application should not be regarded as being limited to the specific forms stated in the embodiments, and the protection scope of the present application also extends to equivalent technical means that can be thought of by those skilled in the art according to the inventive concept.

Claims

1. Pneumatic step excitation device for lathe frequency response test, characterized by: It includes a cylinder for applying an exciting force to a simulated workpiece, a two-position five-way manual control valve for controlling the cylinder, and a force sensor, an acceleration sensor, and a signal analysis system for obtaining the frequency response characteristics of the lathe; The simulated workpiece is pre-installed on the lathe, and the cylinder is fixed to the lathe tool holder through the cylinder mounting bracket, and the cylinder is connected to the air source through a two-position five-way manual control valve; the telescopic rod of the cylinder is aligned with the simulated workpiece, and a piston impact head is provided at the end of the telescopic rod of the cylinder, and a force sensor is provided near the end of the telescopic rod of the cylinder, and an acceleration sensor is provided on the simulated workpiece, and the force sensor and the acceleration sensor are electrically connected to the signal analysis system respectively; the force sensor measures the exciting force emitted by the cylinder and sends it to the signal analysis system, and the acceleration sensor measures the vibration acceleration signal of the simulated workpiece and sends it to the signal analysis system, and the signal analysis system derives the frequency response characteristics of the lathe according to the received exciting force and vibration acceleration signals.

2. The pneumatic step excitation device for lathe frequency response testing according to claim 1, characterized in that: The cylinder and the simulated workpiece are arranged vertically in a horizontal plane, or the cylinder and the simulated workpiece are arranged vertically in a vertical plane, or the axis of the cylinder and the axis of the simulated workpiece are arranged collinearly.

3. The pneumatic step excitation device for lathe frequency response testing according to claim 1, characterized in that: The piston impact head is made of rubber, nylon, aluminum alloy or steel.

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