Error measurement device and method for a numerically controlled machining center

Abstract

The present application relates to the field of machine tool optical detection, and more particularly to a numerical control machining center error measurement device and method, the measurement device comprising a machine tool main body, which comprises a workbench and an electric spindle; a laser autocollimator is installed on an adjusting base for adjusting to a horizontal state; a five-prism is fixedly arranged in a mirror frame, the mirror frame is fixedly installed in a stable base, and the stable base is detachably installed on the workbench; a calibration assembly comprises a calibration table, a mounting seat and a stage, the upper end of the calibration table is coaxially installed with the electric spindle, the outer wall of the calibration table is orthogonally provided with a centering screw, and the mounting seat is orthogonally provided with a leveling screw; a mirror is fixedly installed in a lens seat, and the lens seat is fixedly installed at the bottom of the stage. The present application realizes a closed loop of the whole process of measurement from optical path building, mirror centering, perpendicularity calibration and data acquisition, greatly improving the efficiency and accuracy of the machine tool spindle rotation precision measurement.

Description

Technical Field

[0001] This invention relates to the field of machine tool optical inspection technology, and in particular to an error measurement device and method for CNC machining centers. Background Technology

[0002] With the rapid development of mechanical technology, electrical technology and CNC technology, the machining accuracy of CNC machining centers is getting higher and higher. Among them, the rotational accuracy of CNC machine tools is an important indicator of the accuracy of CNC machining centers, which directly affects the roundness, cylindricity and surface quality of the machined parts.

[0003] Currently, the rotational accuracy of machine tool spindles is mainly tested using autocollimators. However, when testing vertical spindles, traditional autocollimators require the instrument to be placed vertically and aligned with the spindle end face, which is difficult to operate and has poor stability. At the same time, traditional reflective targets rely on their own machining accuracy to ensure perpendicularity to the spindle, and once there is an installation deviation, it cannot be compensated for, lacking effective calibration methods. Summary of the Invention

[0004] The purpose of this invention is to provide a CNC machining center error measurement device and method to solve the above-mentioned technical problems.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A CNC machining center error measuring device, comprising:

[0007] The main body of the machine tool includes a worktable and an electric spindle;

[0008] A laser autocollimator is mounted on an adjustment base for adjusting to a horizontal state. The adjustment base is fixed on a tripod, which is mounted on one side of the machine tool body.

[0009] A pentaprism is fixed inside a frame, which is fixedly installed in a stable base, and the stable base is detachably installed on a workbench.

[0010] The calibration assembly includes a calibration platform, a mounting base, and a stage. The upper end of the calibration platform is coaxially mounted with the electric spindle. The outer wall of the calibration platform is orthogonally provided with self-aligning threaded parts, and the mounting base is orthogonally provided with leveling threaded parts. The self-aligning threaded parts are used to adjust the horizontal displacement of the stage in the orthogonal direction, and the leveling threaded parts are used to adjust the axial rotation of the stage in the orthogonal direction.

[0011] A reflector is fixedly installed inside a lens holder, which is fixedly installed at the bottom of a stage. The horizontally emitted laser beam from the laser autocollimator is deflected by a pentaprism and then directed vertically toward the reflector. The reflected beam is deflected again by the pentaprism and then enters the laser autocollimator.

[0012] As a further embodiment of the present invention: a tapered shank is fixedly provided at the center of the upper end of the calibration platform, and the tapered shank is coaxially fitted into the tapered hole of the electric spindle.

[0013] As a further embodiment of the present invention: mounting holes are orthogonally distributed on the outer wall of the calibration platform, and horizontal fixing sleeves are fixed in each mounting hole. The self-aligning threaded component is threadedly installed in the horizontal fixing sleeve. The mounting base is installed in the calibration platform. The bottom center of the mounting base passes through the calibration platform and is fixedly connected to the top of the stage. The end of the self-aligning threaded component extends into the calibration platform and abuts against the outer wall of the mounting base.

[0014] As a further aspect of the present invention: the bottom of the mounting base is provided with orthogonally distributed mating grooves, and the bottom of the calibration platform is provided with a receiving groove along the orthogonal direction. A ball bearing is adapted to be installed in the receiving groove, and the ball bearing rolls against the corresponding mating groove.

[0015] As a further embodiment of the present invention: a support is provided on the outer wall of the stage extending in an orthogonal direction, a rotating shaft seat is fixed at the upper end of the support, a rotating shaft is rotatably installed in the rotating shaft seat along the radial direction, an extension ring is fixed at the bottom of the calibration stage, and flexible rotating sleeves are orthogonally distributed on the outer wall of the extension ring, and the rotating shaft and the corresponding flexible rotating sleeve are rotatably engaged.

[0016] As a further embodiment of the present invention: vertical fixing sleeves are fixedly provided on each of the brackets, the leveling threaded component is threadedly installed in the vertical fixing sleeves, and pads are orthogonally distributed at the bottom of the calibration platform, with the top of the leveling threaded component abutting against the pads.

[0017] As a further aspect of the present invention: the rotation adjustment directions of the self-aligning threaded parts located on the same straight line are opposite, and the rotation adjustment directions of the leveling threaded parts located on the same straight line are also opposite.

[0018] A method for measuring the error of a CNC machining center, using the aforementioned CNC machining center error measuring device, includes the following steps:

[0019] Step 1: Equipment assembly. Mount the pentaprism on the worktable using the stabilizing base, mount the laser autocollimator on the tripod using the adjusting base, and coaxially assemble the calibration table into the tapered hole of the electric spindle using the tapered shank.

[0020] Step 2: Align the optical path. Turn on the laser autocollimator and adjust it by adjusting the base so that the optical axis is horizontally aligned with the pentaprism incident surface. Then, use the self-aligning screw to precisely align the reflector and observe the display screen until a clear reflected crosshair image appears.

[0021] Step 3: Mirror perpendicularity calibration. The mirror is precisely leveled by adjusting the leveling thread, and then the electric spindle is rotated 180°. The radial runout of the reflected cross image before and after the rotation is recorded until the radial runout of the reflected cross image is less than the threshold, thus completing the perpendicularity calibration.

[0022] Step 4: Measurement and Calculation. Start the electric spindle and rotate it to the set speed. After the speed stabilizes, synchronously collect the runout displacement signal of the laser autocollimator. Continuously collect the set number of revolutions and repeat the measurement at least 3 times. Calculate the average value, and then calculate the true rotational error of the electric spindle based on the radial runout.

[0023] The beneficial effects of this invention are:

[0024] (1) By integrating the laser autocollimator, pentaprism, reflector and calibration components into a complete detection system, the reflector of the calibration components is used for centering and leveling, so that the reflector is precisely perpendicular to the axis of the electric spindle. During the detection process, the beam is horizontally directed from the laser autocollimator to the pentaprism, and after being turned by the pentaprism, it is vertically directed to the reflector. The reflected beam returns along the original path and is turned by the pentaprism again before being directed to the laser autocollimator. The radial runout of the reflected signal is detected to accurately measure the actual rotation error of the electric spindle. Thus, a closed loop of the entire measurement process from optical path construction, mirror centering, perpendicularity calibration and data acquisition is realized, which greatly improves the efficiency and accuracy of the measurement of the machine tool spindle rotation accuracy.

[0025] (2) By setting the angle adjustment component, the orthogonally distributed self-aligning threaded parts and leveling threaded parts form two independent adjustment structures. When self-aligning, the push-pull action of the two sets of self-aligning threaded parts in the orthogonal direction is used to realize the translational fine adjustment of the reflector. When leveling, the pitch and yaw fine adjustment of the reflector is realized by the two sets of leveling threaded parts. The structure is simple and compact, the operation is convenient and quick, the adjustment accuracy is high, and it can meet the detection requirements of the electric spindle rotation error. Attached Figure Description

[0026] The invention will now be further described with reference to the accompanying drawings.

[0027] Figure 1 This is a schematic diagram of the overall structure of the measuring device in this invention.

[0028] Figure 2 This is a schematic diagram of the measurement state of the measuring device in this invention.

[0029] Figure 3 This is a schematic diagram of the measurement optical path of the pentaprism in this invention.

[0030] Figure 4 This is a schematic diagram of the installation of the calibration component in this invention.

[0031] Figure 5This is a schematic diagram of the adjustment component in this invention.

[0032] Figure 6 This is a schematic diagram of the internal structure of the calibration platform in this invention.

[0033] Figure 7 This is a schematic diagram of the stage in this invention.

[0034] Figure 8 This is a schematic diagram of the centering state of the present invention.

[0035] Figure 9 This is a schematic diagram of the leveling state of the present invention.

[0036] In the diagram: 1. Machine tool body; 101. Worktable; 102. Electric spindle; 2. Laser autocollimator; 201. Adjustment base; 202. Tripod; 3. Pentagonal prism; 301. Frame; 302. Stabilizing base; 4. Adjustment assembly; 410. Calibration platform; 411. Taper shank; 412. Self-aligning threaded component; 4121. Horizontal fixing sleeve; 413. Ball bearing; 4131. Receiving groove; 414. Pad; 415. Extension ring; 4151. Flexible rotating sleeve; 420. Mounting base; 421. Mating groove; 430. Stage; 431. Bracket; 432. Spindle seat; 4321. Rotary shaft; 433. Leveling threaded component; 4331. Vertical fixing sleeve; 5. Reflector; 501. Lens holder. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Please see Figures 1-7 As shown, the present invention is a CNC machining center error measuring device, comprising:

[0039] The machine tool body 1 includes a worktable 101 and an electric spindle 102.

[0040] The laser autocollimator 2 is mounted on the adjustment base 201 for adjustment to a horizontal state. The adjustment base 201 is fixed on the tripod 202, which is mounted on one side of the machine tool body 1.

[0041] The pentaprism 3 is fixed inside the frame 301, which is fixedly installed inside the stabilizing base 302. The stabilizing base 302 is detachably installed on the worktable 101.

[0042] The calibration assembly 4 includes a calibration platform 410, a mounting base 420, and a stage 430. The upper end of the calibration platform 410 is coaxially mounted with the electric spindle 102. The outer wall of the calibration platform 410 is orthogonally provided with self-aligning threaded parts 412. The mounting base 420 is orthogonally provided with leveling threaded parts 433. The self-aligning threaded parts 412 are used to adjust the horizontal displacement of the stage 430 in the orthogonal direction, and the leveling threaded parts 433 are used to adjust the axial rotation of the stage 430 in the orthogonal direction.

[0043] The reflector 5 is fixedly installed inside the lens holder 501, which is fixedly installed at the bottom of the stage 430. The horizontal beam emitted by the laser autocollimator 2 is deflected by the pentaprism 3 and then directed vertically toward the reflector 5. The reflected beam is deflected again by the pentaprism 3 and then enters the laser autocollimator 2.

[0044] Specifically, by integrating the laser autocollimator 2, pentaprism 3, reflector 5, and calibration component 4 into a complete detection system, the reflector 5 is aligned and leveled by the calibration component 4, ensuring that the reflector 5 is precisely perpendicular to the axis of the electric spindle 102. During the detection process, the light beam is horizontally directed from the laser autocollimator 2 to the pentaprism 3, then perpendicularly directed to the reflector 5 after being deflected by the pentaprism 3. The reflected beam returns along the same path and is deflected again by the pentaprism 3 before being directed back to the laser autocollimator 2. The radial runout of the reflected signal is detected to accurately measure the true rotational error of the electric spindle 102. This achieves a closed-loop measurement process from optical path setup, mirror alignment, perpendicularity calibration, and data acquisition, greatly improving the efficiency and accuracy of machine tool spindle rotation accuracy measurement.

[0045] like Figure 4 and Figure 5 As shown, a tapered shank 411 is fixedly provided at the center of the upper end of the calibration table 410, and the tapered shank 411 is coaxially fitted into the tapered hole of the electric spindle 102.

[0046] Specifically, the calibration table 410 is coaxially mounted with the tapered hole of the electric spindle 102 via a tapered shank 411. This serves as the mounting basis and positioning reference for the entire adjustment assembly: the tapered hole of the electric spindle 102 is a high-precision positioning reference for the machine tool spindle, and its axis is the spindle rotation axis. The tapered shank 411 adopts the same taper as the tapered hole, utilizing the self-centering characteristic of the tapered surface to achieve automatic centering. At the same time, the tapered shank 411 is connected to a pull rod on the internal axis of the electric spindle 102 via a pull claw. The pull rod can apply a tension force to the tapered shank 411, ensuring that the calibration table 410 and the reflector 5 do not shift during rotation testing.

[0047] like Figure 5 , Figure 6 and Figure 8As shown, mounting holes are orthogonally distributed on the outer wall of the calibration platform 410. Horizontal fixing sleeves 4121 are fixed in each mounting hole. Self-aligning threaded parts 412 are threadedly installed in the horizontal fixing sleeves 4121. Mounting base 420 is installed in the calibration platform 410. The bottom center of the mounting base 420 passes through the calibration platform 410 and is fixedly connected to the top of the stage 430. The end of the self-aligning threaded part 412 extends into the calibration platform 410 and abuts against the outer wall of the mounting base 420.

[0048] Furthermore, the mounting base 420 has orthogonally distributed mating grooves 421 at its bottom, and the calibration platform 410 has a receiving groove 4131 at its bottom along the orthogonal direction. A ball bearing 413 is fitted into the receiving groove 4131, and the ball bearing 413 rolls against the corresponding mating groove 421.

[0049] Specifically, when aligning the mounting base 420, by rotating two relatively distributed self-aligning threaded parts 412, the mounting base 420 is pushed to make a small displacement ΔX in one direction. At the same time, by utilizing the rolling contact between the ball 413 and the mating groove 421, the friction of the mounting base 420 during the displacement process can be greatly reduced, thereby reducing the impact of friction on the accuracy of the displacement process. Through the two sets of orthogonally distributed self-aligning threaded parts 412, the mounting base 420 can be independently fine-tuned in the orthogonal direction, thereby realizing the self-aligning function of the mounting base 420 and the reflector 5.

[0050] like Figure 6 , Figure 7 and Figure 9 As shown, a support 431 extends along the orthogonal direction on the outer wall of the stage 430. A rotating shaft seat 432 is fixed at the upper end of the support 431. A rotating shaft 4321 is rotatably installed in the rotating shaft seat 432 along the radial direction. An extension ring 415 is fixed at the bottom of the calibration stage 410. Flexible rotating sleeves 4151 are orthogonally distributed on the outer wall of the extension ring 415. The rotating shaft 4321 and the corresponding flexible rotating sleeve 4151 are rotatably engaged.

[0051] Furthermore, vertical fixing sleeves 4331 are fixedly installed on the brackets 431, and leveling threaded parts 433 are threadedly installed in the vertical fixing sleeves 4331. Pads 414 are orthogonally distributed at the bottom of the calibration platform 410, and the top of the leveling threaded parts 433 abuts against the pads 414.

[0052] Specifically, when leveling the mounting base 420, by rotating the two relatively distributed leveling threaded parts 433, the stage 430 can be slightly deflected Δθ along the axial direction. During the rotation, the flexible rotating sleeve 4151 and the pad 414 both have a certain elastic deformation space, so that the stage 430 can be independently rotated and fine-tuned in the orthogonal direction, thereby realizing the leveling function of the stage 430 and the reflector 5.

[0053] like Figure 8 and Figure 9 As shown, the rotation adjustment directions of the self-aligning threaded parts 412 located on the same straight line are opposite, and the rotation adjustment directions of the leveling threaded parts 433 located on the same straight line are also opposite.

[0054] Specifically, when centering the reflector 5, turning the centering thread 412 at one end clockwise requires turning the centering thread 412 at the other end counterclockwise. This mutual locking mechanism ensures stability during centering and locks the adjusted orientation. Similarly, the same operation is performed on the leveling thread 433 at both ends during leveling.

[0055] The working principle of this invention is as follows: Figures 1-8 As shown, in use, first, the pentaprism 3 is mounted on the worktable 101 via the stabilizing base 302, and the laser autocollimator 2 is mounted on the tripod 202 via the adjusting base 201. The calibration table 410 is coaxially assembled into the tapered hole of the electric spindle 102 via the tapered shank 411. The laser autocollimator 2 is turned on, and the laser autocollimator 2 is adjusted via the adjusting base 201 so that the optical axis is horizontally aligned with the incident surface of the pentaprism 3. Then, the reflector 5 is precisely aligned via the self-aligning thread 412, and the display screen is observed until a clear reflected crosshair image appears. Finally, the reflector 5 is precisely leveled via the leveling thread 433, thereby completing the optical path calibration and the mirror perpendicularity calibration. After calibration, the electric spindle 102 is started to rotate to the set speed. After the speed stabilizes, the beam is horizontally directed from the laser autocollimator 2 to the pentaprism 3. After being deflected by the pentaprism 3, it is vertically directed to the reflector 5. The reflected beam returns along the original path and is deflected again by the pentaprism 3 before being directed to the laser autocollimator 2. The true rotational error of the electric spindle 102 is accurately measured by detecting the radial runout of the reflected signal.

[0056] The present invention also provides a method for measuring the error of a CNC machining center, which uses the above-mentioned CNC machining center error measuring device and includes the following steps:

[0057] Step 1: Equipment assembly. The pentaprism 3 is mounted on the worktable 101 via the stabilizing base 302. The laser autocollimator 2 is mounted on the tripod 202 via the adjusting base 201. The calibration table 410 is coaxially assembled into the tapered hole of the electric spindle 102 via the tapered shank 411.

[0058] Step 2: Align the optical path. Turn on the laser autocollimator 2 and adjust the laser autocollimator 2 by adjusting the base 201 so that the optical axis is horizontally aligned with the incident surface of the pentaprism 3. Then, use the self-aligning threaded part 412 to precisely align the reflector 5 and observe the display screen until a clear reflected cross image appears.

[0059] Step 3: Mirror perpendicularity calibration. The mirror 5 is precisely leveled by adjusting the leveling thread 433. Then, the electric spindle 102 is rotated 180°, and the radial runout of the reflected cross image before and after the rotation is recorded. The perpendicularity calibration is completed when the radial runout of the reflected cross image is less than the threshold.

[0060] Step 4: Measurement and calculation. Start the electric spindle 102 to rotate to the set speed. After the speed stabilizes, synchronously collect the runout displacement signal of the laser autocollimator 2. Continuously collect the set number of revolutions and repeat the measurement no less than 3 times. Calculate the average value, and then calculate the true rotation error of the electric spindle 102 based on the radial runout.

[0061] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A CNC machining center error measuring device, characterized in that, include: The machine tool body (1) includes a worktable (101) and an electric spindle (102). A laser autocollimator (2) is mounted on an adjustment base (201) for adjustment to a horizontal state. The adjustment base (201) is fixed on a tripod (202), which is mounted on one side of the machine tool body (1). A pentaprism (3) is fixed inside a frame (301), which is fixedly installed inside a stabilizing base (302), which is detachably installed on a workbench (101); The calibration assembly (4) includes a calibration platform (410), a mounting base (420), and a stage (430). The upper end of the calibration platform (410) is coaxially mounted with the electric spindle (102). The outer wall of the calibration platform (410) is orthogonally provided with self-aligning threaded parts (412). The mounting base (420) is orthogonally provided with leveling threaded parts (433). The self-aligning threaded parts (412) are used to adjust the horizontal displacement of the stage (430) in the orthogonal direction. The leveling threaded parts (433) are used to adjust the axial rotation of the stage (430) in the orthogonal direction. The reflector (5) is fixedly installed in the lens holder (501), and the lens holder (501) is fixedly installed at the bottom of the stage (430). The horizontal beam emitted by the laser autocollimator (2) is turned by the pentaprism (3) and then vertically directed towards the reflector (5). The reflected beam is turned again by the pentaprism (3) and then enters the laser autocollimator (2).

2. The error measuring device for a CNC machining center according to claim 1, characterized in that, A tapered shank (411) is fixedly provided at the center of the upper end of the calibration platform (410), and the tapered shank (411) is coaxially fitted into the tapered hole of the electric spindle (102).

3. The error measuring device for a CNC machining center according to claim 1, characterized in that, Mounting holes are orthogonally distributed on the outer wall of the calibration platform (410). Horizontal fixing sleeves (4121) are fixed in each mounting hole. The self-aligning threaded component (412) is threadedly installed in the horizontal fixing sleeve (4121). The mounting seat (420) is installed in the calibration platform (410). The bottom center of the mounting seat (420) passes through the calibration platform (410) and is fixedly connected to the top of the stage (430). The end of the self-aligning threaded component (412) extends into the calibration platform (410) and abuts against the outer wall of the mounting seat (420).

4. The error measuring device for a CNC machining center according to claim 2, characterized in that, The mounting base (420) has orthogonally distributed mating grooves (421) at its bottom, and the calibration platform (410) has a receiving groove (4131) at its bottom along the orthogonal direction. A ball bearing (413) is fitted in the receiving groove (4131), and the ball bearing (413) rolls against the corresponding mating groove (421).

5. The error measuring device for a CNC machining center according to claim 1, characterized in that, The outer wall of the stage (430) is provided with a bracket (431) extending in an orthogonal direction. A rotating shaft seat (432) is fixed at the upper end of the bracket (431). A rotating shaft (4321) is installed radially inside the rotating shaft seat (432). An extension ring (415) is fixed at the bottom of the calibration stage (410). Flexible rotating sleeves (4151) are orthogonally distributed on the outer wall of the extension ring (415). The rotating shaft (4321) and the corresponding flexible rotating sleeve (4151) are rotatably engaged.

6. The error measuring device for a CNC machining center according to claim 5, characterized in that, Vertical fixing sleeves (4331) are fixedly installed on each of the brackets (431). The leveling threaded part (433) is threadedly installed in the vertical fixing sleeve (4331). The calibration platform (410) is orthogonally distributed with pads (414) at the bottom. The top of the leveling threaded part (433) abuts against the pad (414).

7. The error measuring device for a CNC machining center according to claim 1, characterized in that, The self-aligning threaded parts (412) located on the same straight line have opposite rotation adjustment directions, and the leveling threaded parts (433) located on the same straight line also have opposite rotation adjustment directions.

8. A method for measuring the error of a CNC machining center, employing the CNC machining center error measuring device as described in claim 1, characterized in that, Includes the following steps: Step 1: Equipment assembly. Install the pentaprism (3) on the worktable (101) through the stabilizing base (302). Install the laser autocollimator (2) on the tripod (202) through the adjusting base (201). Coaxially assemble the calibration table (410) into the tapered hole of the electric spindle (102) through the tapered shank (411). Step 2: Align the optical path, turn on the laser autocollimator (2), adjust the laser autocollimator (2) by adjusting the base (201) so that the optical axis is horizontally aligned with the incident surface of the pentaprism (3), then precisely align the reflector (5) by adjusting the self-aligning threaded part (412), and observe the display screen until a clear reflected cross image appears; Step 3: Mirror perpendicularity calibration. The mirror (5) is precisely leveled by adjusting the leveling thread (433). Then, the electric spindle (102) is rotated 180°, and the radial runout of the reflected cross image before and after the rotation is recorded until the radial runout of the reflected cross image is less than the threshold, thus completing the perpendicularity calibration. Step 4: Measurement and calculation. Start the electric spindle (102) to rotate to the set speed. After the speed stabilizes, synchronously collect the runout displacement signal of the laser autocollimator (2), continuously collect the set number of revolutions, and repeat the measurement no less than 3 times to calculate the average value. Then, calculate the true rotation error of the electric spindle (102) based on the radial runout.

Images