TWI398877B - Straightness error measurement device - Google Patents

Description

Straightness error measuring device

The invention relates to a direct measurement technology of a linear slide rail, in particular to a low-cost and high-precision straightness error measuring device, and further capable of instantaneously measuring the straightness of the motion platform in the stroke. error.

According to precision measurement and mechanical parts inspection, it is one of the most important items in precision machining. The inspection of dimensions, workmanship, fit and geometry of mechanical processing products depends on the correct measurement technology concept and precision measuring tools. To be done. In the motion of precision machining platform, the multi-degree of freedom azimuth changes and affects the error of each target. Because the motion platform is designed and assembled via linear components, rotating platform and other components, there are multiple degrees of freedom motion, and various motion platforms in the machine. The characteristics will affect the accuracy of the entire machine and the quality of the processed product. The positioning of the machined workpiece, the installation of precision parts and the position and attitude of the target object in space require up to six degrees of freedom to measure and adjust or control. Therefore, it is necessary to put forward higher requirements for the detection of multiple degrees of freedom, and it is desirable to simultaneously measure the multiple degrees of freedom of components, components or target objects in space, and the higher the cost of the high precision measurement system, the lower the cost and the speed. A simple measurement system is quite important.

Since the precision platform motion is a multi-degree of freedom azimuth change and affects the error of each target, as shown in Figure 1, the saddle (10) is provided with a linear displacement motion platform (20), when the motion platform (20) is along the X When moving in the axial direction, a six-degree-of-freedom error is generated including three linear displacement errors δ _x ( x ), δ _y ( x ), δ _z ( x ) and three angular displacement errors ε _x ( x ), ε _y ( x ) with ε _z ( x ). Since the motion platform (20) is designed and assembled via linear components, rotating components and other components with multiple degrees of freedom, the characteristics of the various motion platforms (20) in the machine will affect the accuracy of the entire machine and the quality of the processed product. The positioning of the workpiece to be machined, the installation of precision parts, and the position and attitude of the target object in space require up to six degrees of freedom for measurement and adjustment or control. Therefore, it is necessary to put forward higher requirements for the detection of multiple degrees of freedom, and it is desirable to simultaneously measure the multiple degrees of freedom of components, components or target objects in space. The precision motion platform (20) mostly uses the optical ruler as its online real-time positioning measurement, and provides feedback signals for positioning control. Therefore, a corresponding optical ruler is installed on each moving axis for mobile positioning measurement, but for each The error of one moving axis in both horizontal and vertical directions ( δ _y ( x ) and δ _z ( x )) cannot be measured. Taking the machine tool as an example, the current technology uses the offline correction method to first correct the straightness error, and the measurement result is filed and input to the controller for compensation, but this method is not an instant measurement method.

Furthermore, the offline direct measurement method according to the foregoing is offline correction using a straightness correction method of optical interference or a straightness gauge, and the straightness correction mode of optical interference is as shown in FIG. 2, which is A dual-frequency laser source (31) is split into two channels of light in different directions by a special polarized beam splitter (32) [also known as Wollaston稜鏡], which is directed to a fixed straight reflection through different paths. The mirror (33) (34) is then reflected back to the interferometer (35). If the straight mirror (33) (34) is displaced up and down by Δz, the path of the two beams changes, one beam travels and the other travels shorten. The difference between the two strokes is . In the same way, the reflected beams recombine to produce interference fringes, and the interference fringe changes are converted into the magnitude of Δz, which is the straightness correction method. However, this method can only provide offline correction, and can not cope with the needs of the mobile platform for real-time measurement.

In other words, it is important to develop a straightness error measurement system that is high-precision, low-cost, and quick and easy on-line.

The reason is that the inventors have in-depth discussion on the problems faced by the above-mentioned existing linear slides in the direct measurement, and actively pursued solutions through years of experience in research and development and manufacturing of related industries, and have been continuously researching. And the trial, finally successfully developed a straightness error measurement device, in order to solve the inconvenience and trouble that the existing measurement system can not combine low cost and high precision, and further achieve the purpose of online real-time measurement.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a straightness error measuring device which is capable of simplifying the structure, making the manufacturing easier, reducing the cost, and simultaneously meeting the requirements of high precision.

A second object of the present invention is to provide a straightness error measuring device capable of instantaneously measuring the straightness error of the moving platform on the line during the displacement stroke of the moving platform.

To this end, the present invention mainly implements the objects and effects of the present invention through the following technical means: the measuring device is disposed on a linear slide rail, wherein the linear slide rail comprises a saddle and a a moving platform linearly moving on the saddle, and the measuring device comprises: an optical reading head, which is mounted on the moving platform, and the optical reading head corresponds to any linear surface of the saddle, and the optical reading head is provided There is a collimated light source, and the optical read head is provided with a focusing lens on the side of the collimated light source opposite to the linear surface of the saddle, so that the collimated light source passes through the focusing lens to form a focused beam, and the optical reading head is further provided with a spot position sense. a detector, the spot position sensor and the tangential plane of the focus lens are perpendicular to the optical axis of the focused beam; a reflective element is disposed on the linear surface of the saddle corresponding to the optical pickup, and the reflective element is placed on the focused beam Half of the optical path.

Therefore, after the light source in the optical pickup of the present invention emits the collimated beam to the focusing lens by using the foregoing technical means of the present invention, a focusing beam can be emitted to the reflecting element by the focusing lens, and the focused beam is transmitted through the reflecting component. After the reflection is received by the spot position sensor, the spot position sensor can measure the positional change of the focus spot of the focused beam by the spot position sensor, thereby calculating the horizontal straightness error of the motion platform, and reaching the online instant The purpose of the measurement makes the invention more effective than the learner in terms of "small structure, low cost, measurement accuracy, and measurement immediacy".

Please refer to FIG. 1 , the straightness error measuring device provided by the present invention, mainly The invention includes: a straightness error measuring device for a linear motion platform, and a specific embodiment of the measuring device of the present invention and its components, as illustrated in the accompanying drawings, all of which relate to front and rear, left and right, top and bottom The upper and lower portions, as well as the horizontal and vertical references, are merely for convenience of description and are not intended to limit the invention, nor to limit its components to any position or spatial orientation. The drawings and the dimensions specified in the specification may be varied in accordance with the design and needs of the specific embodiments of the present invention without departing from the scope of the invention.

For a detailed configuration of the straightness error measuring device of the present invention, please refer to the figures shown in FIG. 3 and FIG. 4, the linear sliding rail structure includes a saddle (50) and a moving platform (60), wherein the saddle ( 50) is provided with a linear moving element (55) (such as a lead screw), and the moving platform (60) has a passive element (65) (such as a lead screw) for the linear moving element (55) to be engaged The platform (60) can perform linear movement on the saddle (50) (such as X-axis displacement), and the structural design and operation principle of the saddle (50) and the motion platform (60) of the linear slide are the same as those of the existing one. And the present invention is not described again; and with regard to the features of the present invention, please refer to FIG. 5 and FIG. 6 simultaneously, the optical platform (60) is provided with an optical read head (70), and the optical read head ( 70) and corresponding to any linear surface of the saddle (50), and does not affect the working area when the moving platform (60) moves; and as shown in FIG. 7, the optical reading head (70) is provided with a collimated light source ( 71), the collimated light source (71) may be selected from a light emitting diode or a thunder emitting collimated light The second reading body (70) is provided with a focusing lens (72) on the side of the collimating light source (71) opposite to the reflecting element (80), so that the collimated light source (71) emits a collimated beam ( L1) can form a focused beam (L2) through the focusing lens (72), and a spot position sensor (75) is further disposed in the optical pickup (70), and the focusing lens (72) and the spot position are The tangent plane of the sensor (75) must be perpendicular to the optical axis of the focused beam (L2) and the focused beam (L3) reflected by the reflective element (80), so that the spot position sensor (75) can detect incident light. The position change of the point, the displacement of the motion platform (60) is calculated by the change of the position of the light spot, and the position sensor (75) of the spot can be a one-dimensional or two-dimensional position sensor or four-quadrant position sensing. The present invention is based on a one-dimensional position sensor having two light sensing faces forming two quadrants. When the light source is incident on the spot position sensor (75), the incident light spot can cover the two light sensing faces, and the signals output by the two quadrant light sensing faces are calculated. The X-axis displacement changes; further, the saddle (50) is provided with a reflective element (80) on the linear surface corresponding to the optical pickup (70), and the reflective element (80) may be selected from a grating or a mirror of an optical scale. And the reflective element (80) is placed at half of the optical path of the aforementioned focused beam (L2) as a reflecting surface for causing a straightness error in the horizontal direction when the moving platform (60) is displaced, so that the optical pickup ( 70) A change in the distance from the reflective element (80); thereby forming a straightness error measuring device that combines low cost and high precision with on-line measurement.

Through the foregoing structural design, the present invention is actually operated as shown in FIG. 3 and FIG. 7. When the moving platform (60) is displaced, the optical pickup (70) is driven to synchronously move and scan the reflective element ( a reflecting surface of 80), and a collimated beam (L1) emitted by the collimated light source (71) generates a focused beam (L2) emitted toward the reflecting element (80) through the focusing lens (72), the focused beam (L2) The focused beam (L3) reflected by the reflective element (80) is received by the spot position sensor (75) in the optical pickup (70), and then the spot position sensor (75) is adjusted to Initially, the focused beam (L3) is incident perpendicularly to the origin of the spot position sensor (75); when the moving platform (60) moves, the spot position sensing of the optical pickup (70) is also driven at the same time. (75), so when the moving platform (60) has a horizontal straightness error, the spot position sensor (75) is caused to shift horizontally, and the incident focused beam (L3) is incident to the spot. Position change of the position sensor (75) to instantly measure the horizontal straightness error of the motion platform (60) by position change; The measuring device of the invention has the requirements of low cost and high precision, and can perform real-time straightness error measurement on the line, and further provides the precise control direction of the motion platform (60), and the precision of the nanometer level. Measurement.

The detailed description of the preferred embodiments of the present invention is intended to be limited to the scope of the invention, and is not intended to limit the scope of the invention. The patent scope of this case.

In summary, this case is not only innovative in terms of space type, but also can enhance the above-mentioned multiple functions compared with the customary items. It should fully comply with the statutory invention patent requirements of novelty and progressiveness, and apply for it according to law. This invention patent application, in order to invent invention, to the sense of virtue.

10‧‧‧ saddle

20‧‧‧ sports platform

31‧‧‧Double-frequency laser source

32‧‧‧polar polarizer

33‧‧‧straight mirror

34‧‧‧straight mirror

35‧‧‧Interfer mirror

50‧‧‧ saddle

55‧‧‧Linear moving components

60‧‧‧ sports platform

65‧‧‧ Passive components

70‧‧‧Optical read head

71‧‧‧ Collimated light source

72‧‧‧focus lens

75‧‧‧ spot position sensor

80‧‧‧reflecting elements

L1‧‧‧ collimated beam

L2‧‧‧ focused beam

L3‧‧‧ focused beam

Figure 1 is a schematic diagram of the six degrees of freedom error of the motion platform.

Figure 2 is a schematic diagram of straightness correction for optical interference.

Figure 3 is a schematic view showing the appearance of the measuring device of the present invention.

Figure 4 is a perspective exploded view of the measuring device of the present invention.

Figure 5 is a top plan view of the measuring device of the present invention.

Figure 6 is a side cross-sectional view of the measuring device of the present invention.

Figure 7 is a schematic diagram showing the construction and operation principle of the optical pickup in the measuring device of the present invention.

70‧‧‧Optical read head

71‧‧‧ Collimated light source

72‧‧‧focus lens

75‧‧‧ spot position sensor

80‧‧‧reflecting elements

L1‧‧‧ collimated beam

L2‧‧‧ focused beam

L3‧‧‧ focused beam

Claims (4)

A straightness error measuring device is disposed on a linear slide rail, wherein the linear slide rail comprises a saddle and a motion platform linearly movable on the saddle, and the measuring device comprises: An optical reading head is disposed on the moving platform, and the optical reading head corresponds to any linear surface of the saddle, and a collimated light source is disposed in the optical reading head, and the optical reading head is opposite to the saddle in the collimated light source A focusing lens is disposed on one side of the linear surface, so that the collimated light source passes through the focusing lens to form a focused beam, and the optical reading head is further provided with a spot position sensor, and the spot position sensor and the tangent plane of the focusing lens The optical axis of the focused beam is perpendicular; a reflective element is disposed on the linear surface of the saddle corresponding to the optical pickup, and the reflective element is placed at half of the optical path of the focused beam. The straightness error measuring device according to claim 1 , wherein the collimated light source of the optical pickup is selected from a light emitting diode or a laser diode that emits collimated light. The straightness error measuring device according to claim 1 or 2 , wherein the optical spot position sensor of the optical pickup is selected from a one-dimensional or two-dimensional or four-quadrant position sensor. The straightness error measuring device according to claim 1 , wherein the reflecting element is selected from a grating or a mirror of an optical scale.