阅读说明：本技术 一种抑制精密机床直线轴重复定位误差的装配方法 (Assembly method for inhibiting repeated positioning errors of linear shaft of precision machine tool ) 是由 何改云 孙光明 张大卫 史盼盼 于 2019-09-12 设计创作，主要内容包括：本发明公开一种抑制精密机床直线轴重复定位误差的装配方法,包括以下步骤：(1)将待装配零件放置于20±0.5℃的恒温环境中,静置一天后进行装配；(2)装配主导轨,并测量主导轨在水平和竖直方向上的装配误差e<Sub>v1</Sub>和e<Sub>h1</Sub>；刮研主导轨的安装基面直到e<Sub>v1</Sub>和e<Sub>h1</Sub>满足设计要求为止；(3)装配副导轨,并测量副导轨在水平和竖直方向上的装配误差e<Sub>v2</Sub>和e<Sub>h2</Sub>；刮研副导轨的安装基面直到e<Sub>v2</Sub>和e<Sub>h2</Sub>满足要求为止；(4)装配滚珠丝杠并测量其装配误差；刮研滚珠丝杠的安装基面直到满足设计要求为止；(5)装配光栅尺并测量其装配误差；刮研光栅尺的安装基面直到满足要求为止；(6)将工作台安装到导轨滑块上；(7)调整滚珠丝杠的预拉伸量；(8)最终完成装配。(The invention discloses an assembly method for inhibiting repeated positioning errors of a linear shaft of a precision machine tool, which comprises the following steps of: (1) placing the parts to be assembled in a constant temperature environment of 20 +/-0.5 ℃, standing for one day and then assembling; (2) assembling the main guide rail and measuring the assembling error e of the main guide rail in the horizontal and vertical directions v1 And e h1 (ii) a Scraping the mounting base surface of the main guide rail up to e v1 And e h1 Until the design requirements are met; (3) assembling the secondary guide rail and measuring the assembly error e of the secondary guide rail in the horizontal and vertical directions v2 And e h2 (ii) a Scraping the mounting base surface of the secondary guide rail to e v2 And e h2 Until the requirements are met; (4) assembling the ball screw and measuring the assembling error of the ball screw; scraping the mounting base surface of the ball screw until the design requirement is met; (5) assembling a grating ruler and measuring the assembling error of the grating ruler; scraping the mounting base surface of the grating ruler until the requirements are met; (6) mounting a workbench on a guide rail slide block; (7) adjusting the prestretching amount of the ball screw; (8) and finally finishing the assembly.)

1. An assembly method for inhibiting repeated positioning errors of a linear shaft of a precision machine tool is characterized by comprising the following steps of:

(1) placing the parts to be assembled in a constant temperature environment of 20 +/-0.5 ℃, standing for one day and then assembling;

(2) assembling the main guide rail and measuring the assembling error e of the main guide rail in the horizontal and vertical directions_v1And e_h1；

(3) Judgment e_v1And e_h1If the design requirements are met, the next step is carried out if the design requirements are met, and if the design requirements are not met, the mounting base surface of the main guide rail is scraped and the step (2) is repeated until the step e is finished_v1And e_h1Until the design requirements are met;

(4) assembling the secondary guide rail and measuring the assembly error e of the secondary guide rail in the horizontal and vertical directions_v2And e_h2；

(5) Judgment e_v2And e_h2If the design requirements are met, the next step is carried out if the design requirements are met, and if the design requirements are not met, the mounting base surface of the auxiliary guide rail is scraped, and the step (4) is repeated until the step e is finished_v2And e_h2Until the design requirements are met;

(6) assembling the ball screw and measuring the assembling error of the ball screw;

(7) judging whether the assembly error of the ball screw meets the design requirement, if so, carrying out the next step, and if not, scraping the mounting base plane of the ball screw and repeating the step (6) until the assembly error of the ball screw meets the design requirement;

(8) assembling a grating ruler and measuring the assembling error of the grating ruler;

(9) judging whether the assembly error of the grating ruler meets the design requirement, if the assembly error meets the design requirement, carrying out the next step, and if the assembly error does not meet the design requirement, scraping the mounting base plane of the grating ruler, and repeating the step (8) until the assembly error of the grating ruler meets the design requirement;

(10) mounting a workbench on a guide rail slide block;

(11) adjusting the prestretching amount of the ball screw;

(12) and (5) measuring the repeated positioning error of the workbench, judging whether the repeated positioning error meets the design requirement, and repeating the step (11) if the repeated positioning error does not meet the design requirement until the position is met and finally the assembly is finished.

Technical Field

The invention belongs to the technical field of assembly of precision machine tools, and particularly relates to an assembly method for inhibiting repeated positioning errors of a linear shaft of a precision machine tool.

Background

With the development of modern machine tool industry towards the direction of automation, high speed, precision and the like, the precision requirement of products on the machine tool is higher and higher, the repeated positioning error of the machine tool is more and more emphasized by people, and the key for improving the overall performance of the machine tool is to improve the comprehensive accuracy of the machine tool. The repeated positioning error reflects the stability and consistency of machine tool positioning, is one of important indexes for evaluating the performance of the machine tool, and the current international standard [1] expresses the repeated positioning error by using the expansion uncertainty of the standard deviation of motion deviation:

the repetitive positioning error belongs to an uncompensable error and cannot be suppressed by means of error compensation. At present, in engineering, no effective method for inhibiting the repeated positioning error exists, and in most cases, repeated disassembly and reassembly are carried out according to the experience of an assembler until the repeated positioning error meets the requirements of users.

[1] Part 2 of the national standard machine tool inspection general rule of the GB/T17421.2-2000 people's republic of China: determination of the positioning accuracy and the repeatability of the positioning accuracy of a numerical control axis

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides an assembly method for inhibiting the repeated positioning error of a linear shaft of a precision machine tool.

The purpose of the invention is realized by the following technical scheme:

an assembly method for inhibiting repeated positioning errors of a linear shaft of a precision machine tool comprises the following steps:

(1) placing the parts to be assembled in a constant temperature environment of 20 +/-0.5 ℃, standing for one day and then assembling;

(2) assembling the main guide rail and measuring the assembling error e of the main guide rail in the horizontal and vertical directions_v1And e_h1；

(3) Judgment e_v1And e_h1If the design requirements are met, the next step is carried out if the design requirements are met, and if the design requirements are not met, the mounting base surface of the main guide rail is scraped and the step (2) is repeated until the step e is finished_v1And e_h1Until the design requirements are met;

(4) assembling the secondary guide rail and measuring the assembly error e of the secondary guide rail in the horizontal and vertical directions_v2And e_h2；

(5) Judgment e_v2And e_h2If the design requirements are met, the next step is carried out if the design requirements are met, and if the design requirements are not met, the mounting base surface of the auxiliary guide rail is scraped, and the step (4) is repeated until the step e is finished_v2And e_h2Until the design requirements are met;

(6) assembling the ball screw and measuring the assembling error of the ball screw;

(7) judging whether the assembly error of the ball screw meets the design requirement, if so, carrying out the next step, and if not, scraping the mounting base plane of the ball screw and repeating the step (6) until the assembly error of the ball screw meets the design requirement;

(8) assembling a grating ruler and measuring the assembling error of the grating ruler;

(9) judging whether the assembly error of the grating ruler meets the design requirement, if the assembly error meets the design requirement, carrying out the next step, and if the assembly error does not meet the design requirement, scraping the mounting base plane of the grating ruler, and repeating the step (8) until the assembly error of the grating ruler meets the design requirement;

(10) mounting a workbench on a guide rail slide block;

(11) adjusting the prestretching amount of the ball screw;

(12) and (5) measuring the repeated positioning error of the workbench, judging whether the repeated positioning error meets the design requirement, and repeating the step (11) if the repeated positioning error does not meet the design requirement until the position is met and finally the assembly is finished.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

because the repeated positioning error of the linear shaft belongs to an uncompensable error and is difficult to control, the invention provides an assembly method for inhibiting the repeated positioning error, and the repeated positioning error of the linear shaft is effectively inhibited by controlling links such as environment temperature, assembly error of a guide rail, assembly error of a lead screw, pre-stretching amount of the lead screw and the like, so that the assembly efficiency is greatly improved.

Drawings

FIG. 1 is a schematic assembly flow diagram of the method of the present invention.

FIG. 2a is a schematic view of a two-rail error shape; FIG. 2b is a schematic view of a parallelism test in a vertical direction; fig. 2c is a schematic diagram of the parallelism test in the horizontal direction.

Fig. 3 is a schematic view of error detection of the mounting base of the slide on the table.

Fig. 4 is a schematic diagram of error detection between the slider mounting base and the lead screw on the table.

FIG. 5 is a schematic diagram of the detection of coaxiality error between the motor base and the worktable.

Fig. 6 is a schematic diagram of detecting coaxiality error of the motor base and the bearing seat.

Fig. 7 is a schematic view showing adjustment of an assembly error of the ball screw.

FIG. 8 is a diagram showing the variation rule of the repeated positioning error of a linear shaft of a certain machine tool along with the pretensioning amount of a screw rod.

Fig. 9 is a schematic drawing of the pretensioning of the screw.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples. 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. 1, the present invention provides an assembly method for suppressing the repeated positioning error of the linear axis of a precision machine tool. The method comprises the following specific steps:

1. controlling the ambient temperature;

placing the parts to be assembled in a constant temperature environment of 20 +/-0.5 ℃, standing for one day and then assembling;

2. suppressing geometric errors of the guide rail; the aim is to make the shape of the geometric error of the assembled guide rail as small as possible in the vertical direction; the geometric errors of the two guide rails are made to be as close as possible in the horizontal direction; the method comprises the following steps:

2.1 geometric error suppression of the Main guide

a) The main guide rail is generally a guide rail close to the grating ruler.

b) Before the main guide rail is assembled, scraping treatment is carried out on an installation base surface of the main guide rail, the scraping amount in the vertical direction follows the principle that the middle of the guide rail in the length direction is large and the two ends of the guide rail are small, namely the scraped base surface is concave, the primary scraping amount is not too large and is controlled to be 5-10 mu m;

c) assembling a main guide rail after primary scraping; note that: the fastening of the guide rail screw should be divided into two steps: firstly, fastening screws by using 0.5 time of screw tightening force in sequence; tightening the screws with the required tightening torque, symmetrically from the middle to the two ends of the rail (the magnitude of the torque depends on the diameter of the screw)

d) The straightness error (flat and side directions) of the main guide rail after installation is tested by using a collimator according to the specification in GB/T17421.1-1998, the full-length straightness is required to be less than or equal to 0.002, the length of the main guide rail is arbitrarily 300, the error is less than or equal to 0.0015/300, and if the design requirement is met, subsequent work is carried out; if the straightness error does not meet the design requirement, the main guide rail is disassembled, the mounting base surface is scraped, and after the main guide rail is reassembled, the straightness error is measured until the straightness error meets the design requirement;

2.2 geometric error suppression of Secondary guideways

a) The secondary guide rails are assembled in the manner b) to d) in 2.1.1.

b) Measuring and adjusting the parallelism error of the two guide rails;

the method specifically comprises the following steps: in the vertical direction, the parallelism error of the auxiliary guide rail and the main guide rail in the vertical direction is tested by using an electronic level meter and a marble flat ruler, as shown in fig. 2(b), the sliding blocks on the two guide rails are pushed to move forwards at the same time, so that the displayed error values of all points of the level meter on the stroke are consistent, and the error values are as small as possible; in the horizontal direction, a dial indicator is used for testing the parallelism error of the auxiliary guide rail and the main guide rail in the vertical direction, as shown in fig. 2(c), the sliding blocks on the two guide rails are pushed to move forwards at the same time, so that the displayed error values of all points on the stroke of the dial indicator are consistent, and the error values are as small as possible; if the error value is exceeded, the auxiliary guide rail is disassembled, the side surface of the mounting base surface of the auxiliary guide rail is scraped, and measurement is carried out again after reassembly until the error value meets the requirement;

3. suppressing geometric errors of the ball screw; the aim is to ensure that the parallelism error of the assembled lead screw and the main guide rail is as small as possible; the inhibition method comprises the following steps:

3.1, detecting errors of the installation surface of the guide rail sliding block of the workbench;

the mounting surface of the guide rail sliding block of the workbench is upward, and the leveling sizing block is used for adjusting the level, so that the level in the longitudinal direction and the transverse direction is less than 0.005 um/m;

3.2 measuring the straightness of the side surface of the workbench, which is mounted with the main guide rail sliding block, and the straightness is less than 0.005um/m, as shown in FIG. 3; rechecking the flatness of the mounting base surface of the guide rail slide block, wherein the flatness is 0.005 um/m; and the parallelism of the base surfaces of the installation sides of the two guide rail sliding blocks is rechecked, and the parallelism is 0.005 um/m.

3.3 selecting a proper detection rod, and pressing the detection rod on the screw nut mounting surface of the workbench;

3.4 placing the flat ruler on the installation surface of the main guide rail-guide rail slide block, installing the micrometer on the flat ruler, and checking the parallelism between the nut detection rod and the flat ruler, wherein the parallelism is less than or equal to 0.002/300 in the flat direction and the side direction as shown in figure 3; and if the requirements are not met, scraping the mounting surface of the screw nut.

3.5 the screw nut is not removed, the workbench is turned over and installed on the guide rail slide block, a leveling sizing block is placed between the workbench and the slide block, the center height of the screw nut is adjusted by utilizing the leveling sizing block, and one sizing block is not installed at first.

3.6 selecting a proper detection rod, and pressing the detection rod on the motor base and the bearing seat;

3.7, mounting the motor base with the inspection rod on the mounting surface of the motor base, and firmly attaching the side positioning surface of the motor base;

3.8 using a feeler gauge to check the contact between the motor base and the mounting surface of the lathe bed, and if the feeler gauge does not meet the requirement, performing scraping treatment;

3.9 fixing the dial indicator on the sliding block of the main guide rail, measuring the parallelism of the upper and side buses of the motor base detection rod to the main guide rail, and requiring that the parallelism is less than or equal to 0.002/300, as shown in figure 5.

3.10 marking a meter to detect a machine tool body motor base detection rod (No. 1) and a workbench nut base detection rod (No. 2), wherein the requirements are +/-0.05, and if the requirements are not met, the positioning mounting surface of the motor base is scraped; if the installation surfaces of the motor seat and the bearing seat are lower than the center of the nut seat, the thickness of the leveling sizing block is adjusted, as shown in figure 4.

3.11 detaching the workbench;

3.12 installing the bearing seat with the prepared detection rod on the bearing seat installation surface of the lathe bed.

3.13. The dial indicator is fixed on a sliding block of the main guide rail, and the parallelism of the upper and side buses of the bearing seat detection rod (No. 3) to the main guide rail is measured, wherein the requirement is less than or equal to 0.002/300.

3.14 checking the coaxiality of the motor seat (No. 1) and the bearing seat checking rod (No. 3), wherein the coaxiality is required to be less than or equal to 0.004, as shown in FIG. 6; if the requirements are not met, the mounting surface of the bearing seat is scraped.

3.15 matching pin holes of the motor base and the bearing seat as shown in figure 7;

3.16 detaching the motor base and the bearing seat detection rod;

3.17 install the both ends of lead screw respectively at motor end and bearing frame to use the pin fixed motor cabinet and bearing frame.

4. Control of the amount of pretension of the screw

The target is that according to the experimental result, the repeated positioning error is firstly reduced and then basically kept unchanged along with the increase of the prestretching amount of the screw, the repeated positioning error of a linear shaft of a certain machine tool is shown in figure 8, and it can be seen from the figure that in a closed ring state, the repeated positioning error is firstly reduced and then tends to be stable along with the increase of the prestretching amount of the screw, so the prestretching amount of the screw needs to be controlled at a reasonable value.

Fastening a pulled end bearing in place according to fastening force, namely assembling the bearing in a bearing seat at the end of a servo motor, loosening a connecting screw of a workbench and a lead screw nut, manually rotating a pulling end nut until the nut is manually rotated, gradually rotating a tightening nut by a fixed step length (10um) or an angle (for example, the locking nut rotates 10 degrees) as shown in figure 9, measuring the repeated positioning error under the pre-stretching condition, and stopping the pre-stretching if the nut is qualified; if not, add one step (re-stretch 10um or rotate 10 again), measure the repeat positioning error again, and so on until it reaches the design requirement. And after the pre-stretching adjustment is finished, screwing a screw for connecting the workbench and the screw-nut pair.

The present invention is not limited to the above-described embodiments. The foregoing description of the specific embodiments is intended to describe and illustrate the technical solutions of the present invention, and the above specific embodiments are merely illustrative and not restrictive. Those skilled in the art can make many changes and modifications to the invention without departing from the spirit and scope of the invention as defined in the appended claims.