CN105404239A - Random attitude measurement method for kinematic calibration of five-shaft hybrid machine tool - Google Patents

Abstract

An arbitrary attitude measurement method for kinematic calibration of a five-axis hybrid machine tool is disclosed. The applicable five-axis hybrid machine tool is mainly composed of a machine tool table and a parallel spindle head. The parallel spindle head has two rotational degrees of freedom and one translational degree of freedom, and can form relative motion with the machine tool table with two translational degrees of freedom. The measurement method is to fix a dial gauge along its normal direction on the parallel spindle head moving platform of the hybrid machine tool, and fix a gauge block on the machine tool table. By controlling the motion of the five-axis hybrid machine tool, the dial indicator is extended by Δl, which corresponds to the displacements of the X-axis, Y-axis and Z-axis of the three-translation of the machine tool are Δx, Δy and Δz respectively; Δx, Δy and Δz are the same as The arccosine function value of the ratio of Δl is equal to the included angles α, β and γ between the normal direction of the moving platform and the X-axis, Y-axis and Z-axis respectively, that is, the attitude of the moving platform is obtained. The measurement method only needs a dial indicator and a gauge block, and has the characteristics of simple operation, economy and practicality; it can obtain arbitrary attitude measurement values with high precision.

Description

An Arbitrary Attitude Measurement Method for Kinematic Calibration of Five-axis Hybrid Machine Tool

technical field

The invention relates to a measuring method based on a contact measuring instrument, more precisely, relates to an arbitrary attitude measuring method used for kinematic calibration of a five-axis hybrid machine tool, and belongs to the technical field of space angle measurement.

Background technique

Five-axis hybrid machine tool is an important equipment for processing large aerospace thin-walled parts. Among them, the five-axis hybrid machine tool composed of two-degree-of-freedom serial mechanism and three-degree-of-freedom parallel mechanism has unique advantages and has attracted more and more attention. The five-axis hybrid machine tool is a CNC machine tool that combines the characteristics of large working space of the series mechanism and large acceleration and high rigidity of the parallel mechanism, aiming at high-speed and high-precision machining. The Ecospeed hybrid machine tool developed by German DST company and the Space-5H hybrid machining center developed by Spanish Fatronik company have been used abroad to process aerospace structural parts. Therefore, the five-axis hybrid machine tool has broad application prospects.

However, in the process of manufacturing and assembling five-axis hybrid machine tools, errors will inevitably occur, so that the terminal of the spindle head of the machine tool after assembly (generally referred to as the parallel mechanism actuation platform) will deviate from the originally designed terminal position, resulting in terminal position and Attitude error, that is, the accuracy of the machine tool will be reduced. In order to ensure that the actual terminal position and attitude of the machine tool are consistent with the designed terminal position and attitude, the accuracy of the machine tool is generally guaranteed through precision design or calibration technology. Precision design is to limit the manufacturing accuracy of each part of the machine tool and the assembly accuracy of each link in the machine tool assembly process in the process of machine tool design. This method is expensive to implement and is not conducive to widespread promotion. The kinematic calibration is to correct the model in the control system by identifying the bar parameters in the kinematic model of the machine tool after the machine tool is manufactured, thereby compensating the machine tool terminal error and improving the machine tool terminal accuracy. Its implementation cost is low, and it is conducive to large-scale promotion.

Generally, kinematic calibration is divided into the following steps: modeling, measurement, identification and compensation. Among them, measurement is the basis of identification and compensation, which directly determines the quality of the calibration effect. The reasons are as follows: First, the higher the measurement accuracy, the better the calibration compensation effect. Because the calibration parameter identification algorithm generally adopts the least squares algorithm, the least squares algorithm essentially fits the measurement information, and finally obtains the best identification parameters. The higher the accuracy of the measurement information, the more accurate the identification parameters obtained by fitting, and the better the calibration compensation effect. Second, the more measurement information, the better the calibration compensation effect. Under the principle of the least squares algorithm, the more measurement information, the parameter identification error caused by the measurement error can be avoided to a certain extent, so that the calibration compensation effect is better.

However, in the current kinematics calibration of five-axis hybrid machine tools, position measurement is relatively easy to implement, while attitude measurement is more difficult. The reasons are: 1. Use special instruments such as inclinometers, laser trackers, ballbars, and CCDs to measure Although the attitude of the five-axis hybrid machine tool can measure any attitude, its cost is high, and the general measurement accuracy cannot reach the measurement accuracy required for kinematic calibration; Often the measurement steps are cumbersome and the measurement attitude is limited. At present, attitude measurement mainly faces three major problems: first, the cost of measurement is high; second, the measured attitude is limited by the measurement method, that is, the attitude of the entire workspace cannot be effectively measured; third, attitude measurement is cumbersome and time-consuming.

Contents of the invention

In view of the above measurement problems and combined with the structural form of the five-axis hybrid machine tool, the present invention proposes an arbitrary attitude measurement method for the kinematic calibration of the five-axis hybrid machine tool; Features, combined with a small number of devices and simple operation steps, the attitude of the parallel spindle head moving platform of the five-axis hybrid machine tool is calculated by length measurement, which improves the measurement accuracy and efficiency, and effectively reduces the measurement cost.

The first technical scheme of the present invention is as follows:

An arbitrary attitude measurement method for kinematic calibration of a five-axis hybrid machine tool. The five-axis hybrid machine tool includes a machine tool table and a parallel spindle head. The parallel spindle head has two rotational degrees of freedom and one translational degree of freedom, and is compatible with the machine tool The workbench can also form relative motion of two translational degrees of freedom, characterized in that the measuring method includes the following steps:

1). Fix the gauge block substrate on the workbench of the five-axis hybrid machine tool, and fix the first gauge block on the gauge block substrate. The first gauge block has three sets of parallel surfaces, and the three sets of parallel surfaces are respectively perpendicular to The three translation axes of the five-axis hybrid machine tool: X axis, Y axis and Z axis;

2).Fix the magnetic base and the dial indicator on the parallel spindle head moving platform of the five-axis hybrid machine tool. The extension direction of the dial indicator rod is along the normal direction of the parallel spindle head moving platform and points to the machine tool table;

3). Control the five-axis hybrid machine tool so that the parallel spindle head movement platform swings to the posture that needs to be measured, and then the five-axis hybrid machine tool can only perform X-axis, Y-axis and Z-axis translation, and its measurement posture includes:

a. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the X-axis: control the parallel movement of the X-axis, Y-axis and Z-axis of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement On one surface of the block, the surface is perpendicular to the X-axis; then control the X-axis movement displacement Δx of the hybrid machine tool, and the elongation of the measuring rod of the dial indicator is recorded as Δl; The included angle of the X-axis movement direction of the machine tool

b. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the Y axis: control the parallel movement of the X axis, Y axis and Z axis of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement On one surface of the block, the surface is perpendicular to the Y axis; then control the Y-axis motion displacement Δy of the hybrid machine tool, and the elongation of the measuring rod of the dial indicator is recorded as Δl; then the parallel spindle head moving platform normal direction and the hybrid The included angle of the Y-axis movement direction of the machine tool

c. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the Z axis: control the X-axis, Y-axis and Z-axis translation of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement On one surface of the block, the surface is perpendicular to the Z-axis; then control the Z-axis motion displacement Δz of the hybrid machine tool, and the elongation of the measuring rod of the dial indicator is recorded as Δl; The included angle of the Z-axis movement direction of the machine tool

The second technical scheme provided by the present invention is:

An arbitrary attitude measurement method for kinematic calibration of a five-axis hybrid machine tool. The five-axis hybrid machine tool includes a machine tool table and a parallel spindle head. The parallel spindle head has two rotational degrees of freedom and one translational degree of freedom, and is compatible with the machine tool The workbench can also form relative motion of two translational degrees of freedom, characterized in that the measuring method includes the following steps:

4). Fix the gauge block substrate on the workbench of the five-axis hybrid machine tool, and fix the first gauge block and the second gauge block on the gauge block substrate at the same time. The first gauge block has three groups of parallel surfaces, and the three groups are mutually parallel. The parallel surfaces are respectively perpendicular to the three translation axes of the five-axis hybrid machine tool: X axis, Y axis and Z axis; at this time, the second gauge block has a surface perpendicular to the Z axis, and the surface is the same as the first gauge block A surface of the block perpendicular to the Z axis has a height difference Δz in the direction of the Z axis;

5). Fix the magnetic base and the dial indicator on the parallel spindle head moving platform of the five-axis hybrid machine tool. The extension direction of the dial indicator rod is along the normal direction of the parallel spindle head moving platform and points to the machine tool table;

6). Control the five-axis hybrid machine tool so that the parallel spindle head movement platform swings to the posture to be measured, and then the five-axis hybrid machine tool can only perform X-axis, Y-axis and Z-axis translation, and its measurement posture includes:

a. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the X-axis: control the parallel movement of the X-axis, Y-axis and Z-axis of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement On one surface of the block, the surface is perpendicular to the X-axis; then control the X-axis movement displacement Δx of the hybrid machine tool, and the elongation of the measuring rod of the dial indicator is recorded as Δl; The included angle of the X-axis movement direction of the machine tool

b. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the Y axis: control the parallel movement of the X axis, Y axis and Z axis of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement On one surface of the block, the surface is perpendicular to the Y axis; then control the Y-axis motion displacement Δy of the hybrid machine tool, and the elongation of the measuring rod of the dial indicator is recorded as Δl; then the parallel spindle head moving platform normal direction and the hybrid The included angle of the Y-axis movement direction of the machine tool

c. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the Z axis: control the X-axis, Y-axis and Z-axis translation of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement One surface of the block, which is perpendicular to the Z-axis; then control the movement of the X-axis and Y-axis of the hybrid machine tool, so that the rod of the dial indicator is compressed and the probe is pressed against one surface of the second gauge block, which is It is perpendicular to the Z axis; at this time, Δz is generated by the height difference between the first gauge block and the second gauge block in the Z axis, and the elongation of the measuring rod of the dial indicator is recorded as Δl; then the normal direction of the moving platform of the parallel spindle head and The included angle of the movement direction of the Z axis of the hybrid machine tool

In the above two technical solutions, the workbench of the five-axis hybrid machine tool is a fixed workbench, or has one translational degree of freedom of the X-axis or the Y-axis, or has two translational degrees of freedom of the X-axis and the Y-axis.

Preferably, the linearity of the X-axis and the Y-axis of the five-axis hybrid machine tool is less than or equal to 0.008mm, the straightness is less than or equal to 0.01mm, and the perpendicularity between the X-axis and the Y-axis is less than or equal to 0.01mm/m.

Preferably, the flatness and perpendicularity of the parallel surfaces of the first gauge block and the second gauge block are less than or equal to 20 μm, and the roughness is less than or equal to 0.8 μm.

Preferably, the range of the dial indicator is greater than or equal to 60mm.

Compared with the prior art, the present invention has the following advantages and outstanding technical effects: ①An arbitrary attitude measurement method for kinematic calibration of a five-axis hybrid machine tool proposed by the present invention fully utilizes the structural characteristics of the five-axis hybrid machine tool : The two-degree-of-freedom series axis is converted into a measurement tool, which effectively reduces the measurement cost. ②An attitude that can measure any pose (position and attitude): its measurement method can measure any attitude in the workspace, which can effectively improve the calibration effect. ③Easy to operate: After fixing the dial indicator and gauge block, the attitude measurement can be realized only by controlling the machine tool to perform X-axis, Y-axis and Z-axis translation, which greatly simplifies the attitude measurement steps and reduces the measurement time. ④ There are two main uses: not only can it be used as a measurement method for kinematic calibration of five-axis hybrid machine tools, but also can be used to measure the attitude of five-axis hybrid machine tools with a certain accuracy in any pose.

Description of drawings

Fig. 1 is a structural schematic diagram of the measuring device of the first technical solution.

Fig. 2 is a schematic diagram of the principle of the measuring method of the present invention.

Figure 3 is a schematic diagram of the compression of the dial indicator rod when measuring the angle between the normal direction of the moving platform of the parallel spindle head and the X-axis in the first scheme and the second scheme.

Figure 4 is a schematic diagram of the elongation of the dial indicator rod when measuring the angle between the normal direction of the moving platform of the parallel spindle head and the X-axis in the first scheme and the second scheme.

Figure 5 is a schematic diagram of the compression of the dial indicator rod when measuring the angle between the normal direction of the moving platform of the parallel spindle head and the Y axis in the first scheme and the second scheme.

Fig. 6 is a schematic diagram of the elongation of the dial indicator rod when measuring the angle between the normal direction of the moving platform of the parallel spindle head and the Y axis in the first scheme and the second scheme.

Fig. 7 is a schematic diagram of the compression of the dial indicator rod when measuring the angle between the normal direction of the moving platform of the parallel spindle head and the Z axis in the first scheme and the second scheme.

Fig. 8 is a schematic diagram of the elongation of the dial indicator rod when measuring the angle between the normal direction of the moving platform of the parallel spindle head and the Z axis in the first scheme.

Fig. 9 is a schematic structural view of the measuring device of the second solution.

Fig. 10 is a schematic diagram of the elongation of the dial indicator rod when measuring the angle between the normal direction of the moving platform of the parallel spindle head and the Z axis in the second scheme.

In the figure: 1- machine tool table; 2- gauge block base plate; 3- first gauge block; 4- measuring rod; 5- dial indicator; 6- magnetic table base; 7- parallel spindle head moving platform; The normal direction of the virtual moving platform of the spindle head; 9-the virtual moving platform of the parallel spindle head; 10-the second gauge block.

detailed description

The principle and specific implementation of the present invention will be described in detail below in conjunction with the accompanying drawings (the following description assumes that the machine tool table has two degrees of freedom series translational motion of the X-axis and the Y-axis).

The specific implementation manner of the first technical solution of the present invention:

As shown in Figure 1, the measuring device of this technical solution includes: machine tool table 1, gauge block substrate 2, first gauge block 3, measuring rod 4, dial indicator 5, magnetic table base 6 and parallel spindle head moving platform 7 , set the three translational directions of the five-axis hybrid machine tool as X axis, Y axis and Z axis respectively.

First, fix the gauge block substrate 2 on the workbench 1 of the five-axis hybrid machine tool, and fix the first gauge block 3 on the gauge block substrate 2. The first gauge block 3 has three sets of parallel surfaces. By adjusting the gauge block substrate 2 in The position and posture on the machine tool workbench 1 can make the first gauge block 3 have three sets of mutually parallel surfaces respectively perpendicular to the three translational axes of the five-axis hybrid machine tool: X axis, Y axis and Z axis.

Then fix the magnetic gauge base 6 and the dial indicator 5 on the parallel spindle head moving platform 7 of the five-axis hybrid machine tool, and adjust the switch of the magnetic gauge base 6 and its support to make the elongation of the measuring rod 4 of the dial gauge 5 The direction is along the normal direction of the parallel spindle head moving platform and points to the machine table 1.

As shown in Figure 1, the five-axis hybrid machine tool is controlled so that the parallel spindle head moving platform 7 swings to the attitude that needs to be measured, and then the five-axis hybrid machine tool can only perform X-axis, Y-axis and Z-axis translation.

As shown in Figure 2, Figure 3 and Figure 4, measure the angle between the normal direction of the parallel spindle head moving platform and the X axis. Control the X-axis, Y-axis and Z-axis translation of the hybrid machine tool, so that the measuring rod 4 of the dial indicator 5 is compressed and the measuring head is pressed on a surface of the first gauge block 3, which is perpendicular to the X-axis. Record this The reading of the dial indicator 5 is l ₁ , and the reading of the X-axis on the control panel of the hybrid machine tool is x ₁ . As shown in FIG. 2 , the normal direction 8 of the virtual moving platform of the parallel spindle head is perpendicular to the virtual moving platform 9 of the parallel spindle head. The solid line part of the normal direction 8 of the virtual moving platform of the parallel spindle head represents the compression amount of the measuring rod 4 of the dial indicator 5 in Fig. A surface for the x-axis is provided. Then as shown in Fig. 4, when controlling the movement of the X-axis of the hybrid machine tool until the reading of the X-axis on the machine tool control panel is _x2 , that is, the first gauge block 3 moves along with the machine tool table 1, so that the measurement of the dial gauge 5 Rod 4 is extended until the indication of dial gauge 5 is l ₂ . Then Δx=|x ₁ -x ₂ |, Δl=|l ₁ -l ₂ |, the included angle between the normal direction of the head moving platform of the parallel spindle and the X-axis motion direction of the hybrid machine tool can be calculated as

As shown in Figure 2, Figure 5 and Figure 6, measure the angle between the normal direction of the parallel spindle head moving platform and the Y axis. Control the X-axis, Y-axis and Z-axis translation of the hybrid machine tool, so that the measuring rod 4 of the dial gauge 5 is compressed and the measuring head is pressed on a surface of the first gauge block 3, which is perpendicular to the Y-axis, and recorded The indication of dial indicator 5 is l ₁ , and the reading of Y axis on the control panel of the hybrid machine tool is y ₁ . As shown in FIG. 2 , the normal direction 8 of the virtual moving platform of the parallel spindle head is perpendicular to the virtual moving platform 9 of the parallel spindle head. The solid line part of the normal direction 8 of the virtual moving platform of the parallel spindle head represents the compression amount of the measuring rod 4 of the dial gauge 5 in Fig. A surface for the Y axis is provided. Then as shown in Figure 6, control the Y-axis movement of the hybrid machine tool until the reading of the Y-axis on the machine tool control panel is y2, that is, the first gauge block ₃ moves with the machine tool workbench 1, so that the measurement of the dial indicator 5 Rod 4 is extended until the indication of dial gauge 5 is l ₂ . Then Δy=|y ₁ -y ₂ |, Δl=|l ₁ -l ₂ |, the included angle between the normal direction of the parallel spindle head moving platform and the Y-axis motion direction of the hybrid machine tool can be calculated as

As shown in Figure 2, Figure 7 and Figure 8, measure the angle between the normal direction of the parallel spindle head moving platform and the Z axis. Control the X-axis, Y-axis and Z-axis translation of the hybrid machine tool, so that the measuring rod 4 of the dial indicator 5 is compressed and the measuring head is pressed on a surface of the first gauge block 3, which is perpendicular to the Z-axis, record this The indication of dial indicator 5 is l ₁ , and the reading of Z axis on the control panel of the hybrid machine tool is z ₁ . As shown in FIG. 2 , the normal direction 8 of the virtual moving platform of the parallel spindle head is perpendicular to the virtual moving platform 9 of the parallel spindle head. The solid line part of the normal direction 8 of the virtual moving platform of the parallel spindle head represents the compression amount of the measuring rod 4 of the dial indicator 5 in Fig. A surface for the Z axis is provided. Then as shown in Figure 8, control the Z-axis movement of the hybrid machine tool until the reading of the Z _- axis on the machine tool control panel is z2, that is, the first gauge block 3 moves with the machine tool table 1, so that the measurement of the dial gauge 5 Rod 4 is extended until the indication of dial gauge 5 is l ₂ . Then Δz=|z ₁ -z ₂ |, Δl=|l ₁ -l ₂ |, the included angle between the normal direction of the parallel spindle head moving platform and the Z-axis motion direction of the hybrid machine tool can be calculated as

The specific embodiment of the second technical solution of the present invention:

The difference between technical solution 2 and technical solution 1 is that if the performance of the translational motion generated by the parallel spindle head is not good, that is, when the parallel spindle head performs the translational motion, the attitude of the parallel spindle head will change, then When measuring the attitude of the moving platform, the hybrid machine tool cannot perform the translational motion of the parallel spindle head. Therefore, Δz in this technical solution is generated by the height difference between the first gauge block 3 and the second gauge block 10 in the Z-axis. The steps of the second technical solution are described in detail below in conjunction with the accompanying drawings:

As shown in Figure 9, the measuring device of this technical solution includes: machine tool table 1, gauge block substrate 2, first gauge block 3, measuring rod 4, dial indicator 5, magnetic table base 6, parallel spindle head moving platform 7 and the first gauge block 10, the three translational directions of the five-axis hybrid machine tool are respectively set as the X axis, the Y axis and the Z axis.

First, fix the gauge block substrate 2 on the workbench 1 of the five-axis hybrid machine tool, and fix the first gauge block 3 and the second gauge block 10 on the gauge block substrate 2 at the same time. The first gauge block 3 has three groups of parallel surfaces. By adjusting the position and attitude of the gauge block base plate 2 on the machine table, the first gauge block 3 can have three sets of parallel surfaces perpendicular to the three translation axes of the five-axis hybrid machine tool: X axis, Y axis and Z axis axis. At this time, the second gauge block 10 has a surface perpendicular to the Z axis, and there is a height difference Δz between the surface and the surface of the first gauge block 3 perpendicular to the Z axis in the direction of the Z axis.

Then fix the magnetic gauge base 6 and the dial indicator 5 on the parallel spindle head moving platform 7 of the five-axis hybrid machine tool, and adjust the switch of the magnetic gauge base 6 and its support to make the elongation of the measuring rod 4 of the dial gauge 5 The direction is along the normal direction of the parallel spindle head moving platform and points to the machine table 1.

As shown in Figure 9, the five-axis hybrid machine tool is controlled so that the parallel spindle head moving platform 7 swings to the posture to be measured, and then the five-axis hybrid machine tool can only perform X-axis, Y-axis and Z-axis translation.

As shown in Figure 2, Figure 3 and Figure 4, measure the angle between the normal direction of the parallel spindle head moving platform and the X axis. Control the X-axis, Y-axis and Z-axis translation of the hybrid machine tool, so that the measuring rod 4 of the dial indicator 5 is compressed and the measuring head is pressed on a surface of the first gauge block 3, which is perpendicular to the X-axis. Record this The reading of the dial indicator 5 is l ₁ , and the reading of the X-axis on the control panel of the hybrid machine tool is x ₁ . As shown in FIG. 2 , the normal direction 8 of the virtual moving platform of the parallel spindle head is perpendicular to the virtual moving platform 9 of the parallel spindle head. The solid line part of the normal direction 8 of the virtual moving platform of the parallel spindle head represents the compression amount of the measuring rod 4 of the dial indicator 5 in Fig. A surface for the x-axis is provided. Then as shown in Fig. 4, when controlling the movement of the X-axis of the hybrid machine tool until the reading of the X-axis on the machine tool control panel is _x2 , that is, the first gauge block 3 moves along with the machine tool table 1, so that the measurement of the dial gauge 5 Rod 4 is extended until the indication of dial gauge 5 is l ₂ . Then Δx=|x ₁ -x ₂ |, Δl=|l ₁ -l ₂ |, the included angle between the normal direction of the head moving platform of the parallel spindle and the X-axis motion direction of the hybrid machine tool can be calculated as

As shown in Figure 2, Figure 5 and Figure 6, measure the angle between the normal direction of the parallel spindle head moving platform and the Y axis. Control the X-axis, Y-axis and Z-axis translation of the hybrid machine tool, so that the measuring rod 4 of the dial gauge 5 is compressed and the measuring head is pressed on a surface of the first gauge block 3, which is perpendicular to the Y-axis, and recorded The indication of dial indicator 5 is l ₁ , and the reading of Y axis on the control panel of the hybrid machine tool is y ₁ . As shown in FIG. 2 , the normal direction 8 of the virtual moving platform of the parallel spindle head is perpendicular to the virtual moving platform 9 of the parallel spindle head. The solid line part of the normal direction 8 of the virtual moving platform of the parallel spindle head represents the compression amount of the measuring rod 4 of the dial gauge 5 in Fig. A surface for the Y axis is provided. Then as shown in Figure 6, control the Y-axis movement of the hybrid machine tool until the reading of the Y-axis on the machine tool control panel is y2, that is, the first gauge block ₃ moves with the machine tool workbench 1, so that the measurement of the dial indicator 5 Rod 4 is extended until the indication of dial gauge 5 is l ₂ . Then Δy=|y ₁ -y ₂ |, Δl=|l ₁ -l ₂ |, the included angle between the normal direction of the parallel spindle head moving platform and the Y-axis motion direction of the hybrid machine tool can be calculated as

As shown in Figure 2, Figure 7 and Figure 10, measure the angle between the normal direction of the moving platform of the parallel spindle head and the Z axis. Control the X-axis, Y-axis and Z-axis translation of the hybrid machine tool, so that the measuring rod 4 of the dial indicator 5 is compressed and the measuring head is pressed on a surface of the first gauge block 3, which is perpendicular to the Z-axis, record this The indication of dial indicator 5 is l ₁ . As shown in FIG. 2 , the normal direction 8 of the virtual moving platform of the parallel spindle head is perpendicular to the virtual moving platform 9 of the parallel spindle head. The solid line part of the normal direction 8 of the virtual moving platform of the parallel spindle head represents the compression amount of the measuring rod 4 of the dial indicator 5 in Fig. A surface for the Z axis is provided. Then as shown in Figure 10, control the X-axis and Y-axis movement of the hybrid machine tool, that is, the second gauge block 10 moves with the machine tool table 1, so that the measuring rod 4 of the dial gauge 5 is compressed and the measuring head is pressed on the first On one surface of the second gauge block 10, the surface is perpendicular to the Z-axis, and the indication of the dial indicator 5 at this time is recorded as l ₂ . As shown in Figure 2, the dotted line part of the normal direction 8 of the virtual moving platform of the parallel spindle head represents the elongation of the measuring rod 4 of the dial indicator 5 in Figure 10 at this time, and the surface perpendicular to the Z axis is defined by the first in Figure 10 One surface of the gauge block 10 perpendicular to the Z-axis is provided. At this time, Δz is generated by the height difference between the first gauge block 3 and the second gauge block 10 in the Z-axis. Then Δl=|l ₁ -l ₂ |, the included angle between the normal direction of the parallel spindle head moving platform and the Z-axis motion direction of the hybrid machine tool can be calculated as

It should be pointed out here that during the fixing process, it is ensured that "the first gauge block 3 has three sets of mutually parallel surfaces that are respectively perpendicular to the three translational axes of the five-axis hybrid machine tool: X axis, Y axis and Z axis", And the accuracy of "making the elongation direction of the measuring rod 4 of the dial gauge 5 along the normal direction of the parallel spindle head moving platform and pointing to the machine table 1" requires the high precision of the first gauge block 3 and the dial gauge 5 itself , It is also necessary to ensure the above-mentioned fixed accuracy through the common calibration benchmark method in factories such as playing watches. The method of standard calibration common in factories such as making a watch is not included in the present invention, so it will not be described in detail here.

It should be pointed out here that there is a formula in theory: cos ² α+cos ² β+cos ² γ=1, so only two angles need to be measured to obtain the attitude of the parallel spindle head moving platform. However, due to factors such as measurement error and numerical truncation, the above formula cannot be fully satisfied. Therefore, two angles can be measured to determine the attitude of the parallel spindle head moving platform, and three angle values in the sense of least squares can be taken from multiple measurements of the same attitude as the attitude of the parallel spindle head moving platform.

Claims (6)

1. An arbitrary attitude measurement method for kinematics calibration of a five-axis hybrid machine tool, wherein the five-axis hybrid machine tool contains a machine tool workbench and a parallel spindle head, and the parallel spindle head has two rotational degrees of freedom and one translational degree of freedom, and It can also form relative motion with two translation degrees of freedom with the machine tool table, and it is characterized in that the measurement method includes the following steps: 1). Fix the gauge block substrate (2) on the workbench of the five-axis hybrid machine tool, and fix the first gauge block (3) on the gauge block substrate. The first gauge block has three groups of parallel surfaces, and the three groups are mutually parallel. The parallel surfaces are respectively perpendicular to the three translation axes of the five-axis hybrid machine tool: X axis, Y axis and Z axis; 2).Fix the magnetic base and the dial indicator on the parallel spindle head moving platform of the five-axis hybrid machine tool. The extension direction of the dial indicator rod is along the normal direction of the parallel spindle head moving platform and points to the machine tool table; 3). Control the five-axis hybrid machine tool so that the parallel spindle head movement platform swings to the posture that needs to be measured, and then the five-axis hybrid machine tool can only perform X-axis, Y-axis and Z-axis translation, and its measurement posture includes: a. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the X-axis: control the parallel movement of the X-axis, Y-axis and Z-axis of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement On one surface of the block, the surface is perpendicular to the X-axis; then control the X-axis movement displacement Δx of the hybrid machine tool, and the elongation of the measuring rod of the dial indicator is recorded as Δl; The included angle of the X-axis movement direction of the machine tool b. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the Y axis: control the parallel movement of the X axis, Y axis and Z axis of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement On one surface of the block, the surface is perpendicular to the Y axis; then control the Y-axis motion displacement Δy of the hybrid machine tool, and the elongation of the measuring rod of the dial indicator is recorded as Δl; then the parallel spindle head moving platform normal direction and the hybrid The included angle of the Y-axis movement direction of the machine tool c. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the Z axis: control the X-axis, Y-axis and Z-axis translation of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement On one surface of the block, the surface is perpendicular to the Z-axis; then control the Z-axis motion displacement Δz of the hybrid machine tool, and the elongation of the measuring rod of the dial indicator is recorded as Δl; The included angle of the Z-axis movement direction of the machine tool 2. An arbitrary attitude measurement method for kinematic calibration of a five-axis hybrid machine tool, wherein the five-axis hybrid machine tool contains a machine tool workbench and a parallel spindle head, and the parallel spindle head has two rotational degrees of freedom and one translational degree of freedom, and It can also form relative motion with two translation degrees of freedom with the machine tool table, and it is characterized in that the measurement method includes the following steps: 1). Fix the gauge block base plate (2) on the workbench of the five-axis hybrid machine tool, and fix the first gauge block (3) and the second gauge block (10) on the gauge block base plate at the same time. The first gauge block has three sets The surfaces parallel to each other, the three groups of parallel surfaces are respectively perpendicular to the three translation axes of the five-axis hybrid machine tool: the X axis, the Y axis and the Z axis; at this time, the second gauge block (10) has a The surface of the Z axis, and the surface and a surface perpendicular to the Z axis of the first gauge block have a height difference Δz in the direction of the Z axis; 2).Fix the magnetic base and the dial indicator on the parallel spindle head moving platform of the five-axis hybrid machine tool. The extension direction of the dial indicator rod is along the normal direction of the parallel spindle head moving platform and points to the machine tool table; 3). Control the five-axis hybrid machine tool so that the parallel spindle head movement platform swings to the posture that needs to be measured, and then the five-axis hybrid machine tool can only perform X-axis, Y-axis and Z-axis translation, and its measurement posture includes: a. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the X-axis: control the parallel movement of the X-axis, Y-axis and Z-axis of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement On one surface of the block, the surface is perpendicular to the X-axis; then control the X-axis movement displacement Δx of the hybrid machine tool, and the elongation of the measuring rod of the dial indicator is recorded as Δl; The included angle of the X-axis movement direction of the machine tool b. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the Y axis: control the parallel movement of the X axis, Y axis and Z axis of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement On one surface of the block, the surface is perpendicular to the Y axis; then control the Y-axis motion displacement Δy of the hybrid machine tool, and the elongation of the measuring rod of the dial indicator is recorded as Δl; then the parallel spindle head moving platform normal direction and the hybrid The included angle of the Y-axis movement direction of the machine tool c. Measure the angle between the normal direction of the moving platform of the parallel spindle head and the Z axis: control the X-axis, Y-axis and Z-axis translation of the hybrid machine tool, so that the measuring rod of the dial indicator is compressed and the measuring head is pressed on the first measurement One surface of the block, which is perpendicular to the Z-axis; then control the movement of the X-axis and Y-axis of the hybrid machine tool, so that the rod of the dial indicator is compressed and the probe is pressed against one surface of the second gauge block, which is It is perpendicular to the Z axis; at this time, Δz is generated by the height difference between the first gauge block and the second gauge block in the Z axis, and the elongation of the measuring rod of the dial indicator is recorded as Δl; then the normal direction of the moving platform of the parallel spindle head and The included angle of the movement direction of the Z axis of the hybrid machine tool 3. The arbitrary attitude measurement method of a kind of five-axis mixed machine tool kinematics calibration according to claim 2, characterized in that: the flatness and perpendicularity of the surfaces parallel to each other on the surfaces of the first gauge block and the second gauge block are less than Equal to 20μm, roughness less than or equal to 0.8μm. 4. The arbitrary posture measurement method for kinematics calibration of a five-axis hybrid machine tool according to claim 1 or 2, wherein the workbench of the five-axis hybrid machine tool is a fixed workbench, or has an X-axis or a Y-axis One translational degree of freedom in the X axis, or two translational degrees of freedom with the X and Y axes. 5. The arbitrary posture measurement method for kinematic calibration of a five-axis hybrid machine tool according to claim 1 or 2, characterized in that: the linearity of the X-axis and Y-axis of the five-axis hybrid machine tool is less than or equal to 0.008mm, The straightness is less than or equal to 0.01mm, and the perpendicularity between the X axis and the Y axis is less than or equal to 0.01mm/m. 6. The arbitrary attitude measurement method for kinematic calibration of a five-axis hybrid machine tool according to claim 1 or 2, characterized in that: the range of the dial indicator is greater than or equal to 60 mm.