CN214418303U

CN214418303U - Air turbulence protective cover for multi-degree-of-freedom error measurement of machine tool

Info

Publication number: CN214418303U
Application number: CN202022785349.4U
Authority: CN
Inventors: 段发阶; 刘文正; 张聪; 傅骁; 余珍鑫; 许昊宇; 李佳欣
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2020-11-26
Filing date: 2020-11-26
Publication date: 2021-10-19
Anticipated expiration: 2030-11-26

Abstract

The utility model discloses an air turbulence protection casing for lathe multi freedom error measurement, air turbulence protection casing include bottom plate and bearing structure, bearing structure is telescopic U-shaped structure, the bottom plate is L shape structure, front panel and rear panel are installed respectively to bearing structure's front end and rear end, be provided with the division board that can rise and contract in the bearing structure, be formed with the cavity between front panel, rear panel, bearing structure and the division board, the front panel is used for being connected with multi freedom error measuring device's laser emission end, the rear panel is used for being connected with multi freedom error measuring device's laser receiving terminal, bearing structure lock joint is on the bottom plate; the telescopic arm of the supporting structure is 12: 1. The multi-freedom-degree error measuring device is small in size, light in weight, low in price, convenient to integrate into a numerical control machine tool and a multi-freedom-degree measuring device, and capable of achieving high-precision and high-stability measurement of long-distance multi-freedom-degree errors of the machine tool.

Description

Air turbulence protective cover for multi-degree-of-freedom error measurement of machine tool

Technical Field

The utility model belongs to the technical field of the precision measurement, especially an air turbulence protective structure for lathe long distance multi freedom error measurement.

Background

The machine tool is an important carrier in the manufacturing industry, has rapid development and wide popularization range, and injects new vitality for the development of the manufacturing industry. With the rapid development of modern mechanical manufacturing technology, higher requirements are put forward on the processing precision of various numerical control machines. Meanwhile, with the rapid development of the fields of large-scale and ultra-large-scale ultra-precision equipment manufacturing industry, large scientific devices and the like, the urgent requirement of long working distance is provided while high precision and high efficiency are required. A typical three axis machine includes 21 geometric errors, namely a six degree of freedom error for each axis, including positioning error, two dimensional straightness error, pitch angle, yaw angle, and roll angle, and an orthogonality error between each two axes. At present, common measurement means such as a laser interferometer, a laser tracking interferometer, a ball rod instrument and the like can only carry out single-parameter measurement in each installation and adjustment, if a plurality of machine tool geometric error parameters are measured, a long and tedious measurement process is needed, time and labor are wasted, and the production efficiency is greatly reduced. Therefore, the method for simultaneously detecting the geometric parameter errors of the machine tool machining equipment and the implementation technology become one of the problems which are commonly discussed and solved by related industries at home and abroad but can not be well solved.

The method for realizing simultaneous measurement of multiple degrees of freedom based on the laser collimation and auto-collimation principles is simple in structure, easy to integrate and low in cost. At present, many laser collimation methods and technologies appear at home and abroad, and a machine tool three-axis five-degree-of-freedom measuring head for realizing measurement based on laser collimation and auto-collimation principles is provided in a patent number 2019109776237 'receiving and transmitting split type five-degree-of-freedom measuring device and method with optical path drift compensation', can simultaneously measure laser angle drift to realize compensation, realizes multi-degree-of-freedom measurement, and can be integrated in a numerical control machine tool. However, these methods and techniques do not consider a reasonable air turbulence protection method, and the accuracy and stability of the measurement are seriously affected. The measurement light beams of laser collimation and auto-collimation are transmitted in an air path, the transmission path is inevitably influenced by air turbulence, the collimation and auto-collimation measurement performance is particularly obvious under long working distance, and the air refractive index is randomly fluctuated due to the existence of the air turbulence, so that the parametric amplitude and the phase of the light waves propagating in the air flow are also randomly fluctuated. Specifically, absorption and scattering of the measuring beam during transmission can result in attenuation and depolarization of the collimated beam energy, flickering of the light intensity, wave surface distortion, positional and directional drift, and the like. When a beam of plane wave enters a turbulent medium, the wave front of the emergent light wave is not a plane but a random curved surface, so that an image formed on a photoelectric detector in an auto-collimation system returns to the auto-collimation system to become fuzzy, distorted, nonuniform variation of light intensity, random variation of a central position and the like, and the accuracy and the stability of the long-distance multi-degree-of-freedom error measurement of the machine tool are seriously influenced. Therefore, the development of the air turbulence protection method and structure for the long-distance multi-degree-of-freedom error measurement of the machine tool is of great significance.

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming not enough among the prior art, provide an air turbulence protection casing for lathe multi freedom error measurement, can realize lathe long distance multi freedom error's high accuracy, high stability measurement. The utility model discloses convert the air torrent field intensity among the measuring beam transmission path into comparatively stable layer flow field, weakened the influence of air torrent disturbance to measurement accuracy and stability among the long distance measuring. Furthermore the utility model provides a torrent protective structure is small light in weight, and the low price is convenient for integrate among digit control machine tool and multi freedom measuring device, realizes high accuracy, the high stability measurement of lathe long distance multi freedom error.

The utility model aims at realizing through the following technical scheme:

an air turbulence protective cover for measuring multi-degree-of-freedom errors of a machine tool comprises a bottom plate and a supporting structure, wherein the supporting structure is of a telescopic U-shaped structure, the bottom plate is of an L-shaped structure, a front panel and a rear panel are respectively installed at the front end and the rear end of the supporting structure, a retractable isolation plate is arranged in the supporting structure, a cavity is formed among the front panel, the rear panel, the supporting structure and the isolation plate, the front panel is used for being connected with a laser emitting end of a multi-degree-of-freedom error measuring device, the rear panel is used for being connected with a laser receiving end of the multi-degree-of-freedom error measuring device, and the supporting structure is buckled on the bottom plate; the telescopic arm of the supporting structure is 12: 1.

Compared with the prior art, the utility model discloses a beneficial effect that technical scheme brought is:

(1) the utility model discloses can realize lathe long distance multi freedom error's high accuracy, high stability measurement. The utility model discloses convert the air torrent field intensity among the measuring beam transmission path into comparatively stable layer flow field, overcome traditional measuring device's not enough, weakened the influence of air torrent disturbance to measurement accuracy and stability among the long distance measurement, provide more even temperature field for measuring the light path simultaneously, further improved measuring precision and stability.

(2) The utility model provides an air turbulence protection casing for lathe long distance multi freedom error measurement, its small light in weight, the low price, be convenient for integrate in digit control machine tool and multi freedom measuring device, realize the high accuracy of lathe long distance multi freedom error, high stability is measured, can know by figure 5, after using the air turbulence protection casing, lathe triaxial five freedom gauge head horizontal straightness accuracy measurement noise has reduced 80%, weaken the influence of air turbulence to measuring by a wide margin, measuring precision and stability have been improved.

Drawings

Fig. 1 is a schematic diagram of the transition of turbulent flow fields to laminar flow fields as the reynolds number of the flow field decreases.

Fig. 2 is a schematic structural view of an air turbulence protection shield.

FIG. 3 is an assembly view of an air turbulence prevention structure in the Y-axis of a machine tool.

Fig. 4 is a schematic diagram of the cavity of the air turbulence protection cover adapted to the three-axis five-degree-of-freedom measuring head of the machine tool.

FIG. 5 is a schematic diagram of horizontal straightness measurement noise of a three-axis five-degree-of-freedom measuring head of a machine tool under the condition of the existence of an air turbulence protective cover.

Detailed Description

The present invention will be described in further detail with reference to the following drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 2, the utility model provides an air turbulence protection casing for lathe long distance multi freedom error measurement, by front panel 1, rear panel 2, bearing structure 3, cavity 4, bottom plate 5 constitutes, bearing structure 3 is telescopic U-shaped structure, bottom plate 5 is L shape aluminum product structure, front panel 1 and rear panel 2 are installed respectively to bearing structure's front end and rear end, be provided with the division board that can rise and contract in the bearing structure 3, front panel, the rear panel, be formed with cavity 4 between bearing structure and the division board, front panel 1 is used for being connected with multi freedom error measuring device's laser emission end 6, rear panel 2 is used for being connected with multi freedom error measuring device's laser receiving terminal 7, bearing structure 3 lock joint is on bottom plate 5;

the air turbulence protective cover can be arranged on any axis of a machine tool, as shown in figure 3, the air turbulence protective cover is arranged on a Y axis of the machine tool, and in consideration of the fact that a laser receiving end of the machine tool multi-degree-of-freedom error measuring device moves along with the Y axis of the machine tool in the measuring process, the air turbulence protective cover is designed into a tension spring type similar to an accordion and can move along with the Y axis of the machine tool and the machine tool multi-degree-of-freedom error measuring device, the expansion ratio of the air turbulence protective cover is 12:1, the long-distance multi-degree-of-freedom error measurement of the machine tool can be met, and the influence of air turbulence on the measurement is reduced; meanwhile, the supporting structure of the air turbulence protective cover is arranged on the L-shaped bottom plate 5, so that the resistance of the air turbulence protective cover during stretching is reduced; meanwhile, the air turbulence protective cover enables the temperature field near the measuring beam to be more uniform, the change of air refraction is reduced, and the measuring precision and stability are further improved.

Based on the air turbulence protection cover, the air turbulence protection method capable of realizing the long-distance multi-degree-of-freedom error measurement of the machine tool specifically comprises the following steps:

the flow patterns of viscous materials are classified into laminar flow, turbulent flow, and transitional flow. The laminar flow fluid flows in layers, only relative sliding is carried out between two adjacent layers of fluid, no transverse mixing exists between the fluids, when the flow velocity of the fluid exceeds a certain value, the fluid does not keep flowing in layers any more, but can move in multiple directions, the flow layers are mixed up, and vortex can occur to enter a turbulent flow state.

The fluid transitions from laminar flow to turbulent flow, as determined by the dimensionless Reynolds number, defined as:

wherein v is the fluid flow rate, d is the equivalent diameter of the pipeline, and upsilon is the kinematic viscosity of the fluid. When R is_eLaminar flow < 2300; when R is_eTurbulent flow is achieved when the flow rate is more than 4000; when 2300 is more than or equal to R_eWhen the flow rate is less than or equal to 4000, the flow rate is excessive.

In this example, the measured indoor wind speed fluctuates in the range of v 0.01m/s to 0.1m/s, and the kinematic viscosity v of air at 20 ℃ and one standard atmospheric pressure is 1.48 × 10^-5m²And/s, the flow field of the measuring light beam is a turbulent flow field, and the measurement precision and stability are greatly influenced by light intensity flicker, wave surface distortion and position and direction drift caused by the fluctuation of the refractive index. As shown in fig. 1, the reynolds number of the flow field where the measuring beam is located is reduced, the turbulent flow field can be converted into a laminar flow field, and when the flow field is constant to the laminar flow field, the maximum equivalent diameter d of the air turbulence protective cover is 0.340 m. Therefore, the air turbulence protective cover with the equivalent diameter d less than 0.340m is used for sealing and protecting the measuring light beam, so that the flow velocity of the flow field where the measuring light beam is positioned is reduced, the flow field where the measuring light beam is positioned can be converted into an air layer flow field from the air turbulence field, and the influence of air turbulence disturbance on the measuring precision and stability in long-distance measurement can be weakened.

See fig. 4, by patent No. 2019109776237 "A machine tool three-axis five-degree-of-freedom measuring head for realizing measurement based on laser collimation and auto-collimation principles, which is provided in a receiving and transmitting split type five-degree-of-freedom measuring device and method with optical path drift compensation, is taken as an example, an adaptive air turbulence protective cover is designed, the cavity length is 376mm, the width is 116mm, the equivalent diameter is 0.177mm, the length is reduced to the minimum length of 0.5m, and the length is extended to the maximum length of 6 m. Under the condition of additionally arranging the air turbulence protective cover, the measured v in the air turbulence protective cover fluctuates within the range of 0.01m/s to 0.03m/s, the gas flow velocity of the flow field where the measuring beam is positioned is greatly reduced, and the Reynolds number R in the air turbulence protective cover can be known through calculation_e< 358.78, the flow field of the measuring beam is successfully converted from the air turbulent flow field to the air layer flow field. The air turbulence protective cover has small volume, light weight and low price, is convenient to be integrated in a numerical control machine tool and a multi-degree-of-freedom measuring device, and can realize high-precision and high-stability measurement of long-distance multi-degree-of-freedom errors of the machine tool. After the air turbulence protective cover is used, the horizontal straightness measurement noise of the five-degree-of-freedom measuring head of the machine tool is reduced by 80%, and the influence of the air turbulence on the measurement is greatly reduced, as shown in fig. 5.

The present invention is not limited to the above-described embodiments. The above description of the embodiments is intended to describe and illustrate the technical solutions of the present invention, and the above embodiments are merely illustrative and not restrictive. Without departing from the spirit of the invention and the scope of the appended claims, the person skilled in the art can make many changes in form and detail within the teaching of the invention.

Claims

1. An air turbulence protective cover for measuring multi-degree-of-freedom errors of a machine tool is characterized by comprising a bottom plate and a supporting structure, wherein the supporting structure is of a telescopic U-shaped structure, the bottom plate is of an L-shaped structure, the front end and the rear end of the supporting structure are respectively provided with a front panel and a rear panel, a retractable isolation plate is arranged in the supporting structure, a cavity is formed among the front panel, the rear panel, the supporting structure and the isolation plate, the front panel is used for being connected with a laser emitting end of a multi-degree-of-freedom error measuring device, the rear panel is used for being connected with a laser receiving end of the multi-degree-of-freedom error measuring device, and the supporting structure is buckled on the bottom plate; the telescopic arm of the supporting structure is 12: 1.