A synchronous visual measurement device and method for the accuracy of the tool tip and tool axis direction of a five-axis machine tool.

Abstract

This invention provides a synchronous visual measurement device and method for the accuracy of the tool tip and tool axis direction of a five-axis machine tool. The device includes: two sets of orthogonally arranged image acquisition units, two sets of telecentric light sources corresponding to the image acquisition units, a double standard ball joint mounted at the end of the machine tool spindle, and a support base. Each image acquisition unit consists of a high-resolution camera and a telecentric lens fixedly connected together. Each telecentric light source consists of a telecentric lens and a light source assembly fixedly connected together. The telecentric lens and the telecentric light source are fixedly connected to the base. The two centers of the double standard ball joint are located in the intersection area of ​​the parallel beams generated by the two sets of telecentric light sources. This invention achieves synchronous measurement of the accuracy of the tool tip and tool axis direction of a five-axis machine tool by using a double standard ball joint mounted at the end of the machine tool spindle, featuring a large measurement range and high measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of visual measurement device technology, specifically to a five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device and method. Background Technology

[0002] Currently, the accuracy inspection of five-axis machine tools mainly relies on the "Dynamic Accuracy Inspection Device and Method for CNC Machine Tools" disclosed in patent application document CN111215967A. This technology uses multiple sensors to simultaneously measure the tool tip position and tool axis direction, solving the accuracy calibration problem caused by separate measurements and improving the accuracy and reliability of spindle inspection. However, this patent has the following drawbacks:

[0003] The measurement range is severely limited: the position measurement range is much smaller than 100mm×100mm×100mm, which cannot cover the full-area accuracy detection requirements of the large stroke machining area of ​​a five-axis machine tool; the tool axis direction measurement angle range is significantly narrower than -90° to 90°, which is difficult to adapt to the synchronous measurement of the large tilt angle motion posture of the machine tool spindle.

[0004] Insufficient spatial adaptability: The layout of multiple sensors is limited by mechanical interference, making it impossible to deploy them flexibly within the machine tool processing area, resulting in measurement blind spots.

[0005] Limited dynamic measurement capability: Due to limitations in sensor sampling rate and field of view, it is difficult to achieve high-precision dynamic synchronous measurement in continuous trajectory motion.

[0006] Patent application CN104625880A discloses a synchronous detection mechanism for the posture and tip position error of a five-axis machine tool, including a swing angle measuring device, a spatial displacement measuring device, a rotation angle measuring device, a mounting device, and a follow-up platform. The swing angle measuring device, spatial displacement measuring device, rotation angle measuring device, and follow-up platform are all mounted on the mounting device. The spatial displacement measuring device measures the three-axis micro-displacement of the tool tip when the rotation center point of the machine tool under test moves along a set trajectory. The swing angle measuring device and the rotation angle measuring device are used to measure the swing angle and rotation angle generated by the machine tool under test, respectively. However, this patent cannot completely solve the existing technical problems, nor can it meet the needs of this invention. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide a five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device and method.

[0008] The five-axis machine tool tip point and tool axis direction accuracy synchronous visual measurement device provided by the present invention includes: two sets of orthogonally arranged image acquisition units, two sets of telecentric light sources corresponding to the image acquisition units, a double standard ball bar installed at the end of the machine tool spindle, and a support base;

[0009] The image acquisition unit consists of a high-resolution camera and a telecentric lens fixedly connected together.

[0010] The telecentric light source is composed of a telecentric lens and a light source assembly fixedly connected together;

[0011] The telecentric lens and telecentric light source are fixedly connected to the base;

[0012] The two centers of the double standard cue are located in the intersection area of ​​parallel beams generated by two sets of telecentric light sources.

[0013] Preferably, the orthogonal arrangement means that the optical axes of the two sets of image acquisition units are perpendicular to each other, and the parallel beams emitted by the two sets of telecentric light sources form an orthogonal light field in space.

[0014] Preferably, the dual standard ball bar is mounted to the end of the machine tool spindle via a tool holder.

[0015] Preferably, the line connecting the centers of the two standard balls on the double standard ball club coincides with the axis of the machine tool spindle.

[0016] Preferably, the device calculates the spatial coordinates of the sphere's center using the following algorithm:

[0017] For each standard ball, the following spatial relationship is satisfied:

[0018]

[0019] in,( M x, M y, M z) represents the spatial position coordinates of the standard sphere in the machine tool coordinate system. X u, X v) and ( Y u, Y v) represents the pixel coordinates of the center of the circle formed by the image of the standard sphere in both cameras. The transformation relationship matrix between the two is composed of the intrinsic parameter matrices of the two cameras and the extrinsic parameter matrices of the two cameras to the machine tool coordinate system.

[0020] Preferably, the spatial coordinates of the centers of the two balls of the double standard cue are measured. M P1 = ( M x1, M y1, M z1) and M P2 = ( M x2, M y2, M z2), thus obtaining the end tool tip point of the machine tool. M P and tool axis direction M V, the expression is:

[0021]

[0022] Preferably, the image acquisition unit uses a sub-pixel visual recognition algorithm based on an edge grayscale model to recognize the projected image of the two standard golf clubs.

[0023] Preferably, the parallel beam intersection area forms a 100mm×100mm×100mm measurement space, and the motion trajectory of the double standard cue sticks within this space can be dynamically acquired.

[0024] Preferably, the dual standard cues simultaneously generate projection images in two directions in an orthogonal light field, and the image acquisition unit identifies the coordinates of the projection centers of the two cues with sub-pixel accuracy.

[0025] The visual measurement method of the five-axis machine tool tip point and tool axis direction accuracy synchronous visual measurement device provided by the present invention includes:

[0026] Step 1: Install the vision measurement device in the machining area of ​​the machine tool, and install the double standard ball bar on the machine tool spindle through the tool holder;

[0027] Step 2: Adjust the position of the machine tool spindle and move the double standard ball bar to the intersection of the two parallel light sources;

[0028] Step 3: Design the measurement trajectory within a 100mm×100mm×100mm measurement space at the intersection of the light sources;

[0029] Step 4: Machine tool running trajectory measurement. The device dynamically acquires the projection image of the double standard ball bar and calculates the tool tip point and tool axis direction of the five-axis machine tool.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] This invention provides a five-axis machine tool tool tip and tool axis direction accuracy synchronous visual measurement device. By using a double standard ball joint installed at the end of the machine tool spindle, it achieves synchronous measurement of the five-axis machine tool tool tip and tool axis direction accuracy. It features a large measurement range (100mm×100mm×100mm position measurement range and -90° to 90° angle measurement range) and high measurement accuracy (1μm position accuracy and 0.001° angle accuracy). Attached Figure Description

[0032] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0033] Figure 1 A schematic diagram of a five-axis machine tool tool tip point and tool axis direction synchronous visual measurement device;

[0034] The diagram shows: 1-Camera, 2-Telecentric lens, 3-Machine tool spindle, 4-Double standard ball bar, 5-Base, 6-Telecentric light source. Detailed Implementation

[0035] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0036] Example

[0037] This invention proposes a five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device. The device consists of two sets of orthogonal telecentric light sources 6 and image receivers, as well as a double standard ball bar 4. It has the characteristics of large field of view and high precision measurement, and can realize synchronous measurement of the tool tip point and tool axis direction accuracy of five-axis machine tools.

[0038] The device consists of two sets of orthogonal telecentric light sources 6 and an image receiver. The telecentric light source 6 comprises a telecentric lens 2 and a light source to achieve parallel light emission. The image receiver comprises a telecentric lens 2 and a high-resolution camera 1 to achieve distortion-free, large depth-of-field, and high-precision projection imaging. The end of the machine tool spindle 3, equipped with dual standard ball bars 4, is moved to the intersection of the two parallel light sources to achieve projection imaging of the dual ball bars in two directions.

[0039] Among them: camera 1 and telecentric lens 2 are fixedly connected, telecentric lens 2 and telecentric light source 6 are fixedly connected to base 5, and double standard ball bar 4 is installed on spindle 3 of the machine tool under test through tool holder.

[0040] A sub-pixel visual recognition algorithm based on an edge grayscale model is employed to identify the spatial coordinates of the two centers of the two standard ball bearings (4) with sub-pixel precision. The coordinates of the midpoint correspond to the position of the machine tool tip, and the spatial vector formed by the coordinates of the two centers represents the direction of the machine tool axis. The relationship between the center pixel coordinates identified by the algorithm and the spatial coordinates of the ball centers in the machine tool coordinate system is as follows:

[0041]

[0042] in,( M x, M y, M z) represents the spatial position coordinates of the standard sphere in the machine tool coordinate system. X u, X v) and ( Y u, Y v) represents the pixel coordinates of the center of the circle formed by the image of the standard sphere in both cameras. The transformation relationship matrix between the two is composed of the intrinsic parameter matrices of the two cameras and the extrinsic parameter matrices of the two cameras to the machine tool coordinate system.

[0043] The spatial coordinates of the two centers of the two balls on the double standard cue can be measured using the above formula. M P1 = ( M x1, M y1, M z1) and M P2 = ( M x2, M y2, M z2), from which the tip point of the machine tool end can be obtained. M P and tool axis direction M V;

[0044]

[0045] This invention also provides a method for synchronous visual measurement of the accuracy of the tool tip and tool axis direction of a five-axis machine tool, comprising:

[0046] 1) The vision measurement device is installed in the machining area of ​​the machine tool, and the double standard ball bar 4 is installed on the machine tool spindle 3 through the tool holder;

[0047] 2) Adjust the position of the machine tool spindle and move the double standard ball bar 4 to the intersection of the two parallel light sources;

[0048] 3) Design the measurement trajectory within a 100mm×100mm×100mm measurement space at the intersection of light sources;

[0049] 4) Machine tool running trajectory measurement: The device dynamically acquires the projection image of the double standard ball bar 4 and calculates the tool tip point and tool axis direction of the five-axis machine tool.

[0050] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0051] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device, characterized in that, Includes: two sets of orthogonally arranged image acquisition units, two sets of telecentric light sources (6) corresponding to the image acquisition units, a double standard ball bar (4) installed at the end of the machine tool spindle (3) and a support base (5); The image acquisition unit is composed of a high-resolution camera (1) and a telecentric lens (2) fixedly connected together; The telecentric light source (6) is composed of a telecentric lens (2) and a light source assembly fixedly connected together; The telecentric lens (2) and the telecentric light source (6) are fixedly connected to the base (5); The two centers of the double standard ball stick (4) are located in the intersection area of ​​the parallel beams generated by the two sets of telecentric light sources (6); The device calculates the spatial coordinates of the sphere's center using the following algorithm: For each standard ball, the following spatial relationship is satisfied: in, The coordinates of the standard sphere in the machine tool coordinate system are the spatial position coordinates. and Let be the pixel coordinates of the center of the circle formed by the image of the standard sphere in both cameras. The transformation relationship matrix between the two is composed of the intrinsic parameter matrices of the two cameras and the extrinsic parameter matrices of the two cameras to the machine tool coordinate system; The spatial coordinates of the two centers of the two balls of the double standard club (4) were measured. and This yields the tip point of the machine tool end. and the direction of the tool axis The expression is: 。 2. The five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device according to claim 1, characterized in that, The orthogonal setting refers to the optical axes of the two sets of image acquisition units being perpendicular to each other, and the parallel beams emitted by the two sets of telecentric light sources (6) forming an orthogonal light field in space.

3. The five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device according to claim 1, characterized in that, The double standard ball bar (4) is mounted on the end of the machine tool spindle (3) via a tool holder.

4. The five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device according to claim 1, characterized in that, The line connecting the centers of the two standard balls of the double standard ball stick (4) coincides with the axis of the machine tool spindle.

5. The five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device according to claim 1, characterized in that, The image acquisition unit uses a sub-pixel visual recognition algorithm based on an edge grayscale model to recognize the projected image of the double standard cue stick (4).

6. The five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device according to claim 1, characterized in that, The parallel beam intersection region is formed The motion trajectory of the double standard cue (4) within the measurement space can be dynamically collected.

7. The five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device according to claim 1, characterized in that, The dual standard cue stick (4) synchronously generates two projected images in an orthogonal light field, and the image acquisition unit identifies the coordinates of the projected center of the two spheres with sub-pixel precision.

8. A visual measurement method based on a five-axis machine tool tool tip point and tool axis direction accuracy synchronous visual measurement device according to any one of claims 1 to 7, comprising: Step 1: Install the vision measurement device in the machining area of ​​the machine tool, and install the double standard ball bar on the machine tool spindle through the tool holder; Step 2: Adjust the position of the machine tool spindle and move the double standard ball bar to the intersection of the two parallel light sources; Step 3: At the intersection of light sources In the measurement space, design the measurement trajectory; Step 4: Machine tool running trajectory measurement. The device dynamically acquires the projection image of the double standard ball bar and calculates the tool tip point and tool axis direction of the five-axis machine tool.

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