On-machine pulse type cleaning method for pollutants on surface of measuring ball of three-coordinate measuring machine

Abstract

An on-machine pulse type cleaning method for pollutants on the surface of a measuring ball of a three-coordinate measuring machine comprises the following steps: shooting the surface of the measuring ball through an image acquisition device, and outputting different depth images to a controller for pollutant quantitative detection: starting a pollutant cleaning task when the quantity of the pollutants exceeds a threshold value; the surface of the measuring ball is cleaned through multi-direction dry ice airflow washing, and after cleaning is completed, the measuring needle returns to the work task of three-coordinate detection of the part. According to the invention, online automatic detection and automatic cleaning of pollutants can be realized, the measurement precision is improved, and the detection efficiency is ensured.

Description

Technical Field

[0001] The present invention relates to a technology in the field of precision detection, specifically a method for in-machine pulsed cleaning of contaminants on the surface of a probe ball of a coordinate measuring machine. Background Art

[0002] A coordinate measuring machine is an extremely precise measuring instrument with extremely high requirements for the environment. However, sometimes debris or particulate matter generated during the workpiece detection process, PM2.5 particles in the air, or the workpiece material itself will adhere to the probe ball of the coordinate measuring machine, causing serious measurement errors, thereby reducing the measurement accuracy of parts. The probe needles of the existing probe heads used in coordinate measuring machines are very fragile. During the cleaning process, the probe needles are extremely easy to be damaged and the cleaning effect is poor, and automatic control cannot be achieved. Summary of the Invention

[0003] In view of the above deficiencies in the prior art, the present invention proposes a method for in-machine pulsed cleaning of contaminants on the surface of a probe ball of a coordinate measuring machine. By using an image acquisition device and image processing technology, the contaminants on the surface of the probe ball are regularly detected. Once the contaminants on the surface of the probe ball exceed the set limit value, the probe needle is moved into the contaminant cleaning device, and the surface of the probe ball is cleaned by dry ice air flow flushing in multiple directions. After the in-machine cleaning is completed, the probe needle returns to the task of part detection, thereby automatically detecting and cleaning contaminants online, improving the measurement accuracy, and ensuring the detection efficiency.

[0004] The present invention is realized through the following technical solutions:

[0005] The present invention relates to an in-machine cleaning method based on an in-machine pulsed cleaning device for contaminants on the surface of a probe ball of a coordinate measuring machine, including: photographing the surface of the probe ball through an image acquisition device and outputting images of different depths to a controller for quantitative detection of contaminants; when the number of contaminants exceeds the threshold, starting a contaminant cleaning task, cleaning by dry ice air flow flushing in multiple directions on the surface of the probe ball, and after the in-machine cleaning is completed, the probe needle returns to the task of three-coordinate detection of parts.

[0006] The in-machine pulsed cleaning device for contaminants on the surface of a probe ball of a coordinate measuring machine includes: a base body, three pairs of two-way two-position electromagnetic directional control valves arranged around its outside, a solenoid valve adapter, a nozzle installation base pipe and a dry ice nozzle, an image acquisition device and a controller. Among them: the two-way two-position electromagnetic directional control valves are fixed to the outside of the base body through mounting seats, the solenoid valve adapter, the nozzle installation base pipe and the dry ice nozzle are sequentially sleeved inside the two-way two-position electromagnetic directional control valves, and the dry ice nozzle extends into the base body and faces the probe needle of the probe head located at the center. The image acquisition device is arranged near the contaminant cleaning device and is connected to the controller. When contaminants on the surface of the probe ball are detected, the probe ball is controlled to move to the position of the image acquisition device, so the image acquisition device does not need to be integrated on the cleaning device.

[0007] For the described quantitative detection of pollutants, the surface of the measuring sphere is photographed at different depths. After synthesizing the images at different depths into one image, the image is converted into a grayscale image, the edges of the pollutants are identified, and then the area occupied by all the pollutants on the surface of the measuring sphere is calculated. Technical effects

[0008] Compared with the prior art, the cleaning device of the present invention is overall compact and lightweight, and can overcome the shortcomings of the existing methods. Through automatic detection and automatic cleaning of pollutants, the measurement accuracy is improved, the precise and efficient cleaning of the coordinate measuring sphere is ensured, the measurement accuracy is improved when measuring parts, and the automatic detection and automatic cleaning of pollutants can improve the efficiency of detecting parts. Description of the drawings

[0009] Figure 1 In the figure, a-d are respectively schematic diagrams of the device of the present invention;

[0010] Figure 2 It is a schematic diagram for adjusting the one-way cleaning distance;

[0011] Figure 3 It is a schematic diagram of the internal structure of the dry ice nozzle;

[0012] Figure 4 It is a schematic diagram of the nozzle arrangement;

[0013] Figure 5 It is a flowchart of the embodiment;

[0014] Figure 6 In the figure, a, b, and c are respectively schematic diagrams of the quantitative detection of pollutants in the embodiment;

[0015] Figure 7 In the figure, a and b are respectively comparison diagrams of the effects of the embodiment. Detailed implementation manners

[0016] Such as Figure 1As shown in the figure, it is a pulsed in-machine cleaning device for the surface contaminants of the probe ball of a coordinate measuring machine according to an embodiment, including: a base body 202, three pairs of two-position two-way electromagnetic directional control valves 204 arranged around its outside, a solenoid valve adapter 205, a nozzle mounting base pipe 206 and a dry ice nozzle 207, an image acquisition device 211 and a controller 212. Among them: The two-position two-way electromagnetic directional control valve 204 is fixed to the outside of the base body 202 through a mounting seat 203. The solenoid valve adapter 205, the nozzle mounting base pipe 206 and the dry ice nozzle 207 are sequentially sleeved and arranged inside the two-position two-way electromagnetic directional control valve 204, and the dry ice nozzle 207 extends into the base body 202 and is directly opposite to the probe of the probe head 208 located at the center. The image acquisition device is arranged near the contaminant cleaning device and is connected to the controller. When contaminants on the surface of the probe ball are detected, the probe ball is controlled to move to the position of the image acquisition device, so the image acquisition device does not need to be integrated on the cleaning device.

[0017] The bottom of the base body 202 is fixedly connected to the coordinate measuring machine through a flange 201.

[0018] Three windows are evenly distributed on the base body 202. These windows communicate the inside of the cleaning device with the surrounding environment, keeping the temperature inside the cleaning device the same as the room temperature, preventing the accumulation of ice crystals or solid dry ice particles on the surface of the probe ball that may be caused by the low temperature inside the device due to dry ice, which affects the measurement effect. In addition, the windows facilitate observing the overall cleaning status.

[0019] A probe rod 209 is provided at the top of the probe head 208, and a probe ball 210 is provided at the end of the probe rod 209. The two form a probe.

[0020] The probe ball 210 is a high-precision ruby standard ball with very small sphericity error that is in direct contact with the workpiece. According to different measurement tasks, probe balls with different specifications and diameters are suitable for different part inspection tasks.

[0021] As Figure 3 As shown in the figure, the dry ice nozzle 207 sequentially includes: an inlet end, a transition region, a main body region and an outlet end. A dry ice air flow directly opposite to the probe ball is ejected through the dry ice nozzle 207 to apply an impact force to achieve a unidirectional cleaning force. The magnitude of this unidirectional cleaning force is determined by the cleaning distance and the inner cavity shape of the nozzle.

[0022] As Figure 1 b and Figure 2 As shown in the figure, the cleaning distance refers to: the cleaning distance between the nozzle and the probe ball is controlled by controlling the pitch of the screw engagement between the dry ice nozzle 207 and the nozzle mounting base pipe 206. The adjustment range of the cleaning distance is 3 - 20 mm. Adjusting the cleaning distance can achieve adjusting the magnitude of the unidirectional cleaning force.

[0023] The transition region is a region where the diameter rapidly expands from the inlet (with a diameter of 0.16 mm) to the main body region (2 mm) to quickly form a dry ice gas flow.

[0024] The inlet end is an elongated tube structure with a diameter of 0.16 mm and a length of 0.3 mm.

[0025] The diameter of the main body region is 2 mm.

[0026] As Figure 4 shown, the uniform distribution means that three nozzles are evenly arranged in the circumferential direction of the substrate 202. The positions of the three dry ice nozzles are 601, 602, and 603 respectively, and the theoretical angle between each position is 120°. In the height direction of the cleaning device substrate 202, the heights of the three nozzles are the same. The arrangement of the three nozzles can not only make the gas flow cover the surface of the measuring sphere in all directions, but also make the cleaning force received by the measuring needle theoretically 0, reducing the possibility of the measuring needle being damaged. Through the processing of parts by a high-precision machining center and high-precision assembly, the machining accuracy of the device substrate 202 and the nozzle mounting base tube 206 and the assembly accuracy between the two are ensured. Then the nozzle is installed in the nozzle mounting base tube 206, and the actual measured force on the measuring needle is less than 0.5 mN, within the allowable range of the force on the measuring needle.

[0027] The pulsed cleaning means that by sending a pulsed opening and closing signal to the solenoid valve, the dry ice gas flow is ejected intermittently instead of continuously. The above measures can reduce the speed of the temperature drop on the surface of the measuring sphere and prevent the accumulation of dry ice particles and ice particles on the surface of the measuring sphere. The window of the device substrate 202 is used to observe the cleaning state and accelerate the recovery of the temperature around the measuring sphere to room temperature.

[0028] As Figure 5 shown, the in-machine cleaning method based on the above device in this embodiment is to photograph the surface of the measuring sphere through an image acquisition device and output images at different depths to the controller for pollutant quantification detection: when the number of pollutants exceeds the threshold, the pollutant cleaning task is started, and the surface of the measuring sphere is cleaned by flushing with dry ice gas flow in multiple directions. After the in-machine cleaning is completed, the measuring needle returns to the work task of the three-coordinate measurement of the part.

[0029] The pollutants refer to debris or particulate matter generated during the workpiece processing, PM2.5 particles in the air, or the workpiece material itself. These pollutants may adhere to the surface of the measuring sphere during the contact three-coordinate measurement process for a period of time.

[0030] The threshold refers to the coverage threshold of pollutants on the surface of the measuring sphere.

[0031] The described cleaning task means: moving the probe to the center of the probe ball surface contaminant cleaning device, and adjusting the magnitude of the unidirectional cleaning force by adjusting the unidirectional cleaning distance according to different specifications of probe balls. Then, a solenoid valve is used for pulsed cleaning, and a dry ice gas flow is ejected from three nozzles evenly distributed in a circle, and the gas flow impacts the surface of the probe ball to clean the contamination.

[0032] The described dry ice gas flow means: a gas flow formed by gaseous carbon dioxide sublimated from dry ice mixed with liquid and solid carbon dioxide particles. The solid dry ice particles overcome the adhesion force of the contaminants to clean the contaminants; the drag force of the gaseous carbon dioxide flushes away the contaminants; the liquid carbon dioxide can dissolve some organic contaminants. Through the above combined actions, the dry ice gas flow can thoroughly clean the contaminants on the surface of the probe ball.

[0033] As Figure 6 shown in Figures 6a, 6b and 6c, the detection of the surface of the probe ball is in progress, as well as the composite photo of the surface of the probe ball and the contaminant detection results obtained by applying the contaminant quantification detection technology in this embodiment.

[0034] As Figure 7 shown in Figures 7a and 7b, the surface of the probe ball cleaned by applying the contaminant cleaning method in this embodiment and the surface of the probe ball before cleaning are shown.

[0035] Compared with the prior art, the present invention uses the physical and chemical mechanisms of dry ice gas flow to clean the surface of the probe ball of the coordinate measuring machine; the magnitude of the unidirectional cleaning force can be adjusted, and generally the resultant force on the probe ball is less than 0.5 mN to ensure that the probe is not damaged; the contaminant cleaning device cooperates with the image acquisition device, and the image acquisition device irregularly monitors the accumulation of contaminants on the surface of the probe ball, which is beneficial to grasping the cleaning timing of the surface of the probe ball and significantly improving the efficiency of detecting parts.

[0036] The above specific implementation can be locally adjusted in different ways by those skilled in the art without departing from the principles and purposes of the present invention. The protection scope of the present invention is subject to the claims and is not limited by the above specific implementation, and all implementation solutions within its scope are restricted by the present invention.

Claims

1. An on-machine cleaning method based on an on-machine pulse cleaning device for the surface contaminants of a three-dimensional coordinate measuring machine ball, characterized in that: include: The image acquisition device is used to photograph the surface of the measuring ball and output images of different depths to the controller for quantitative detection of pollutants: when the number of pollutants exceeds the threshold, the pollutant cleaning task is started, and the surface of the measuring ball is cleaned by flushing the surface with dry ice airflow in multiple directions. After the machine cleaning is completed, the measuring needle returns to the task of three-dimensional detection of the part; The on-machine pulse cleaning device for pollutants on the surface of a measuring ball of a three-coordinate measuring machine comprises: a base body, three pairs of two-position two-way electromagnetic reversing valves arranged on the outside thereof, an electromagnetic valve adapter, a nozzle mounting base pipe and a dry ice nozzle, an image acquisition device and a controller, wherein: the two-position two-way electromagnetic reversing valve is fixed to the outside of the base body through a mounting seat, the electromagnetic valve adapter, the nozzle mounting base pipe and the dry ice nozzle are sequentially sleeved in the two-position two-way electromagnetic reversing valve, and the dry ice nozzle extends into the inside of the base body and faces the probe of the probe located in the center, the image acquisition device is arranged near the pollutant cleaning device and connected to the controller, and when pollutants on the surface of the measuring ball are detected, the measuring ball is controlled to move to the position of the image acquisition device, so the image acquisition device does not need to be integrated on the cleaning device.

2. The on-machine cleaning method based on the on-machine pulse cleaning device for the surface contaminants of the measuring ball of a three-dimensional coordinate measuring machine according to claim 1 is characterized in that: Three windows are evenly distributed on the base body, and the windows allow the interior of the cleaning device to communicate with the surrounding environment.

3. The on-machine cleaning method based on the on-machine pulse cleaning device for the surface contaminants of the three-dimensional coordinate measuring machine ball according to claim 1 is characterized in that: A measuring rod is arranged on the top of the measuring head, and a measuring ball is arranged on the end of the measuring rod, and the two form a measuring needle.

4. The on-machine cleaning method based on the on-machine pulse cleaning device for the surface contaminants of the measuring ball of a three-dimensional coordinate measuring machine according to claim 1 is characterized in that: The dry ice nozzle comprises: an inlet end, a transition area, a main area and an outlet end in sequence. The dry ice nozzle ejects a dry ice airflow directly toward the measuring ball to exert an impact force, thereby realizing a unidirectional cleaning force. The magnitude of the unidirectional cleaning force is determined by the cleaning distance and the inner cavity shape of the nozzle.

5. The on-machine cleaning method based on the on-machine pulse cleaning device for the surface contaminants of the measuring ball of a three-dimensional coordinate measuring machine according to claim 4 is characterized in that: The cleaning distance means that the cleaning distance between the dry ice nozzle and the nozzle mounting base tube is controlled by controlling the screw pitch of the dry ice nozzle and the nozzle mounting base tube. The adjustment range of the cleaning distance is 3-20mm. Adjusting the cleaning distance can adjust the size of the unidirectional cleaning force.

6. The on-machine cleaning method based on the on-machine pulse cleaning device for the surface contaminants of the measuring ball of a three-dimensional coordinate measuring machine according to claim 4 is characterized in that: The transition area is a region where the diameter rapidly expands from the inlet to the main body area, so as to rapidly form a dry ice airflow.

7. The on-machine cleaning method based on the on-machine pulse cleaning device for the surface contaminants of the measuring ball of a three-dimensional coordinate measuring machine according to claim 6 is characterized in that: The inlet end is a slender tube structure with a diameter of 0.16 mm and a length of 0.3 mm; the diameter of the main body area is 2 mm.

8. The on-machine cleaning method based on the on-machine pulse cleaning device for the surface contaminants of the measuring ball of a three-dimensional coordinate measuring machine according to any one of claims 1 to 7, characterized in that: The pulse type means that by sending a pulsed opening and closing signal to the electromagnetic valve, the dry ice airflow is ejected intermittently to reduce the speed at which the temperature of the measuring ball surface decreases, thereby preventing the accumulation of dry ice particles and ice particles on the measuring ball surface.

9. The on-machine cleaning method based on the on-machine pulse cleaning device for the surface contaminants of the measuring ball of a three-dimensional coordinate measuring machine according to claim 1 is characterized in that: The cleaning task is to move the probe to the center of the probe ball surface contaminant cleaning device, and adjust the unidirectional cleaning force by adjusting the unidirectional cleaning distance according to the probe balls of different specifications; then use the solenoid valve for pulse cleaning, and eject dry ice airflow from three nozzles evenly distributed around the circumference, and the airflow impacts the probe ball surface to clean the contamination.

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