Automatic tool setting system of surface grinding machine and contact type tool setting positioning method of automatic tool setting system

Abstract

The invention provides an automatic tool setting system of a surface grinding machine, which is characterized by comprising a machine tool movement mechanism, a tool setting mechanism, a tool setting mechanism, a tool setting mechanism, a tool setting mechanism and a tool setting mechanism, the grinding wheel spindle system is used for driving a grinding wheel to rotate at high speed and providing cutting power; the contact type tool setting sensor is installed on the machine tool workbench and used for generating a physical trigger signal when the grinding wheel makes contact with the contact type tool setting sensor; the signal collecting and processing unit is connected with the tool setting sensor and the numerical control system and used for collecting sensor signals and position coordinate data of the machine tool shaft in real time. According to the invention, the tool setting is carried out under the high-speed rotation state of the grinding wheel, the actual processing working condition is truly simulated, and the maximum point position and the jerk value of the grinding wheel are calculated by acquiring the contact data of a plurality of points on the excircle surface of the grinding wheel. The system can intelligently select the tool setting benchmark according to the machining process requirement, and the problem of workpiece size out-of-tolerance or surface burning caused by grinding wheel jumping is effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tool setting of grinding machines, in particular to an automatic tool setting system of a surface grinder and a contact tool setting positioning method thereof. BACKGROUND

[0002] In the grinding process, tool setting is a key link to determine the relative position of the grinding wheel and the workpiece, which directly determines the machining size precision and surface quality of the workpiece.

[0003] In the prior art, automatic tool setting devices mainly include non-contact (such as photoelectric and laser sensors) and contact (such as mechanical trigger probes) types. The non-contact tool setting device is easily disturbed by grinding fluid, cooling fluid mist and on-site light conditions, resulting in unstable detection signals, high equipment cost and complex maintenance.

[0004] Although the contact tool setting device has strong anti-interference ability, the existing contact tool setting method usually has the following technical defects:

[0005] Ignoring the wheel runout error: the existing contact tool setting is usually a single-point touch in the state of static or low-speed wheel, or only one trigger signal is collected. However, in actual processing, there is obvious radial runout (due to manufacturing error, installation eccentricity or uneven wear of the grinding wheel surface) when the grinding wheel rotates at high speed. Single-point tool setting cannot reflect the dynamic envelope surface of the rotating grinding wheel. If the tool setting point is at the "low point" of the grinding wheel, the "high point" of the grinding wheel during actual processing will cause excessive cutting depth, and even collision or burn the workpiece; if the tool setting point is at the "high point", it will cause excessive idle stroke and reduce the processing efficiency.

[0006] Affected by the surface morphology of the grinding wheel: the grinding wheel surface may have adhesives, local damage or pores, and the existing tool setting method lacks effective data filtering mechanism. Once the sensor touches the defect position on the grinding wheel surface, an incorrect trigger signal will be generated, resulting in distorted tool setting data.

[0007] Signal processing lag: in the contact tool setting process, from the contact of the sensor to the grinding wheel to the signal being received and recorded by the system, there is a certain time delay and mechanical deformation. The existing technology often lacks accurate compensation for such dynamic errors, resulting in limited positioning accuracy.

[0008] Therefore, there is an urgent need for an automatic tool setting system of a surface grinder and a contact tool setting positioning method thereof. SUMMARY

[0009] In view of the deficiencies of the prior art, the present application provides an automatic tool setting system of a surface grinder and a contact tool setting positioning method thereof to solve the problems raised in the background art.

[0010] In order to achieve the above object, the present application is realized by the following technical scheme: An automatic tool setting system of a surface grinding machine, characterized in that, comprising:

[0011] A machine tool motion mechanism, comprising an X-axis, a Y-axis worktable and a Z-axis feed shaft, for driving the workpiece and the grinding wheel to move relatively;

[0012] A grinding wheel spindle system, for driving the grinding wheel to rotate at high speed and providing cutting power;

[0013] A contact type tool setting sensor, installed on the machine tool worktable, for generating a physical trigger signal when the grinding wheel contacts it;

[0014] A signal acquisition and processing unit, connected with the tool setting sensor and the numerical control system, for collecting sensor signals and position coordinate data of the machine tool shafts in real time, and filtering, feature extracting and statistically analyzing the data;

[0015] A numerical control system, for controlling the machine tool motion according to a preset program, receiving the calculation results of the signal acquisition and processing unit, and automatically correcting the workpiece coordinate system or the tool compensation value.

[0016] Preferably, the contact type tool setting sensor is a high-precision mechanical trigger probe or an inductive non-contact displacement sensor, and the contact type tool setting sensor has a protection structure against coolant and iron filings pollution.

[0017] Preferably, a contact type tool setting positioning method adopts the automatic tool setting system of the surface grinding machine, characterized in that, comprising the following steps:

[0018] S1: controlling the machine tool and the grinding wheel to move to obtain an initial tool setting data sequence through the contact type tool setting sensor;

[0019] S2: preprocessing the initial tool setting data sequence, extracting an effective contact signal segment and a corresponding Z-axis coordinate set;

[0020] S3: obtaining distribution characteristics according to the Z-axis coordinate set, calculating the confidence degree of each candidate contact point being a real tool setting point, and eliminating abnormal points to obtain an effective coordinate set ;

[0021] S4: based on the effective coordinate set, analyzing the runout characteristics of the grinding wheel, calculating the highest point position and the average center position of the grinding wheel;

[0022] S5: according to the grinding wheel runout characteristics and a preset machining process strategy, determining a final tool setting coordinate from the contact coordinate set, calculating the actual position of the grinding wheel tip point according to the final tool setting coordinate and the initial position coordinate of the contact type tool setting sensor, and automatically updating the workpiece coordinate system offset or the tool compensation value of the machine tool.

[0023] Preferably, the specific steps of the control machine tool and the grinding wheel motion through the initial tool setting data sequence obtained by the contact tool setting sensor include:

[0024] Install the contact tool setting sensor on the worktable of the surface grinder, and obtain the initial position coordinates of the contact tool setting sensor in the machine tool coordinate system;

[0025] Control the spindle of the machine tool to rotate the grinding wheel at a preset speed, and control the X and Y axes of the machine tool to move the grinding wheel to a preset area above the contact tool setting sensor;

[0026] Perform the tool detection motion, control the Z axis of the machine tool to feed downward, and control the X or Y axis of the machine tool to reciprocate and sweep, collect the trigger signal of the contact tool setting sensor and the corresponding Z axis coordinate of the machine tool in real time, and form the initial tool setting data sequence.

[0027] Preferably, the specific process of performing the tool detection motion includes:

[0028] Control the Z axis of the machine tool to move at a first feed speed to a safe distance position close to the contact tool setting sensor;

[0029] Control the Z axis of the machine tool to switch to a second feed speed for slow downward feeding, and the second feed speed is less than the first feed speed;

[0030] While the Z axis is slowly fed downward, control the X or Y axis to perform a sinusoidal or triangular wave form of reciprocating motion within a preset sweep width range, and the sweep width is greater than the width or diameter of the grinding wheel, so that the outer circular surface of the grinding wheel can cover the sensing area of the contact tool setting sensor.

[0031] Preferably, the specific process of S2 includes:

[0032] Filter the collected initial tool setting data sequence to eliminate high-frequency noise interference;

[0033] Set a trigger threshold, and when the amplitude of the filtered sensor signal exceeds the trigger threshold, mark the time as a suspected contact time;

[0034] Take the data segment within a preset time window forward and backward with each suspected contact time as the center, extract the Z axis coordinate when the sensor signal reaches the peak value in the data segment, and mark it as the candidate contact point coordinate;

[0035] Arrange all candidate contact point coordinates in time sequence to form a Z axis coordinate set , wherein n is the number of candidate contact points.

[0036] Preferably, the specific process of obtaining the effective coordinate set includes:

[0037] Calculate the mean of the set of Z-axis coordinates and the standard deviation ;

[0038] The i-th candidate contact point The degree of deviation from the mean The formula for calculating is:

[0039] ;

[0040] Where, represents the normalized distance of the i-th candidate contact point from the mean; represents the absolute value function;

[0041] According to the degree of deviation Calculate the confidence of each candidate contact point as the true tool contact point , the formula is:

[0042] ;

[0043] Pre-set confidence threshold , the candidate contact point is determined as an abnormal point and is eliminated, and the candidate contact points with higher confidence are retained to form an effective coordinate set .

[0044] Preferably, the specific process of S4 is:

[0045] Perform extreme value analysis on the data in the effective coordinate set , find the maximum value and the minimum value ;

[0046] Calculate the runout of the grinding wheel , the formula is:

[0047] ;

[0048] According to the effective coordinate set Calculate the average contact position of the grinding wheel , the calculation method is as follows:

[0049] ;

[0050] In the formula, m represents the number of midpoints in the effective coordinate set ; the j-th effective contact point ;

[0051] According to the highest point position of the grinding wheel and the average contact position The tool setting correction coefficient alpha is calculated, and the calculation formula is:

[0052] ;

[0053] In the formula, is a minimum value, preventing the denominator from being zero; alpha reflects the offset proportion of the highest point of the grinding wheel relative to the average position.

[0054] Preferably, the specific steps of determining the final tool setting coordinates from the contact coordinate set according to the wheel run-out parameters and the preset machining process strategy comprise:

[0055] Selecting a tool setting strategy according to the grinding process type;

[0056] If the fine grinding mode is selected, the final tool setting coordinates are set as ;

[0057] If the coarse grinding mode is selected, the final tool setting coordinates are set as , wherein beta is a weight coefficient, and the value range is 0-0.5.

[0058] If the run-out value exceeds the preset alarm threshold, an alarm signal is generated and the tool setting process is interrupted.

[0059] Preferably, the specific process of automatically updating the workpiece coordinate system offset or tool compensation value of the machine tool comprises:

[0060] According to the final tool setting coordinates , the actual distance of the grinding wheel bottom surface or outer circle relative to the zero point of the workpiece coordinate system is calculated in combination with the known installation height of the contact tool setting sensor.

[0061] ;

[0062] In the formula, D represents the relative distance between the grinding wheel reference point and the zero point of the workpiece coordinate system, represents the known installation height of the contact tool setting sensor.

[0063] The calculated grinding wheel position data is updated to the tool compensation register or the workpiece coordinate system offset, and the automatic tool setting is completed.

[0064] The application provides an automatic tool setting system of a surface grinding machine and a contact tool setting positioning method thereof, and has the following beneficial effects:

[0065] The present application simulates the actual machining condition by performing tool setting under the high-speed rotating state of the grinding wheel, obtains the contact data of multiple points on the outer circle surface of the grinding wheel through the reciprocating sweeping motion of the X-axis or Y-axis, and calculates the highest point position and the run-out amount of the grinding wheel based on a statistical method, so that the system can intelligently select the highest point or the average position of the grinding wheel as the tool setting reference according to the machining process requirement, the highest point positioning is adopted for fine grinding, the consistency of the cutting depth is ensured, and the problems of workpiece size out-of-tolerance or surface burn caused by the run-out of the grinding wheel are effectively avoided;

[0066] The present application can effectively identify and eliminate abnormal data points caused by the adhesion of foreign matters, local defects or sensor false triggering on the surface of the grinding wheel by performing statistical analysis on the collected Z-axis coordinate set and calculating the confidence of each contact point, and the accuracy and reliability of the final tool setting data are ensured through the multiple screening mechanism, and accidental errors caused by single touch are avoided.

[0067] In the signal processing stage, the present application adopts a low-pass filtering technology to eliminate high-frequency vibration noise, and locks the contact point by extracting the coordinates corresponding to the peak value time of the signal, so that the position error caused by the rising edge or falling edge delay of the contact signal is effectively overcome, the most closely and most real time of the contact between the grinding wheel and the sensor is recorded, and the micron-level positioning accuracy is improved.

[0068] The present application realizes a fully automatic tool setting process without manual intervention, and the system can automatically complete data acquisition, analysis, calculation and coordinate system updating, greatly shortens the auxiliary time, and provides differentiated tool setting strategies (such as using the average position in the coarse grinding mode to improve the utilization rate of the grinding wheel) according to the different characteristics of coarse grinding and fine grinding, thereby further optimizing the machining efficiency under the premise of ensuring the machining quality.

[0069] The present application uses a contact sensor to cooperate with the existing machine tool motion mechanism, without expensive laser or visual equipment, and is low in cost and easy to transform on the existing surface grinder. BRIEF DESCRIPTION OF DRAWINGS

[0070] Figure 1 A contact tool setting sensor installation schematic diagram is provided for the present embodiment;

[0071] Figure 2 A contact tool setting positioning method flowchart of the present application. DETAILED DESCRIPTION

[0072] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0073] As Figure 1 shown, the embodiment of the present application provides an automatic tool setting system of a surface grinder, comprising a machine tool motion mechanism, a grinding wheel spindle system, a contact tool setting sensor, a signal acquisition and processing unit and a numerical control system;

[0074] The machine tool motion mechanism comprises an X-axis, a Y-axis workbench and a Z-axis feed shaft, for driving the workpiece and the grinding wheel to move relatively in multiple axes;

[0075] The grinding wheel spindle system is used to drive the grinding wheel to rotate at high speed, providing cutting power;

[0076] The contact tool setting sensor is installed on the machine tool workbench, for generating a physical trigger signal when the grinding wheel contacts it;

[0077] The signal acquisition and processing unit is connected with the tool setting sensor and the numerical control system, for acquiring sensor signals and position coordinate data of the machine tool axes in real time, and filtering, feature extraction and statistical analysis of the data;

[0078] The numerical control system is used to control the machine tool motion according to a preset program, and receive the calculation results of the signal acquisition and processing unit, to automatically correct the workpiece coordinate system or the tool compensation value.

[0079] In this embodiment, the contact tool setting sensor is a high-precision mechanical trigger probe or an inductive non-contact displacement sensor, and the contact tool setting sensor has a protection structure against coolant and iron filings pollution.

[0080] As Figure 2 shown, the embodiment of the present application further provides a contact tool setting positioning method, which applies the automatic tool setting system of the surface grinder described above, comprising the following steps:

[0081] S1: control the machine tool and the grinding wheel to move to obtain an initial tool setting data sequence through the contact tool setting sensor;

[0082] In this embodiment, the specific process of controlling the machine tool and the grinding wheel to move to obtain an initial tool setting data sequence through the contact tool setting sensor comprises:

[0083] Install the contact tool setting sensor on the workbench of the surface grinder, and obtain the initial position coordinates of the contact tool setting sensor in the machine tool coordinate system;

[0084] Control the machine tool spindle to drive the grinding wheel to rotate at a preset speed, and control the machine tool X-axis and Y-axis to drive the grinding wheel to move to a preset area above the contact tool setting sensor;

[0085] Performing the tool detection movement, controlling the machine tool Z axis to feed down, and controlling the machine tool X axis or Y axis to perform reciprocating micro-motion sweep, collecting the trigger signal of the contact tool detection sensor and the corresponding machine tool Z axis coordinate in real time, and forming the initial tool detection data sequence.

[0086] Specifically, a high-precision contact tool detection sensor is installed on the worktable magnetic chuck of the surface grinder at a proper position, ensuring that the sensor probe is located within the grinding wheel travel range and obtaining the initial position coordinate of the sensor in the machine tool coordinate system.

[0087] It should be noted that the contact tool detection sensor should have a trigger accuracy of microns, and its installation position should be ensured at a known coordinate point in the machine tool motion coordinate system to facilitate subsequent coordinate conversion.

[0088] Starting the grinding wheel spindle to rotate at a preset working speed to simulate the actual machining state.

[0089] Specifically, the grinding wheel is kept rotating to introduce the runout factor of the grinding wheel during tool detection, so as to measure the effective cutting diameter of the grinding wheel, rather than the static diameter.

[0090] Controlling the machine tool Z axis to move the grinding wheel downward, and controlling the machine tool X axis or Y axis to perform micro-reciprocating motion, so that the outer circular surface of the grinding wheel can fully sweep the sensor probe.

[0091] It should be noted that the micro-reciprocating motion of the X axis or Y axis is to avoid the interference of local defects or adhesions on the surface of the grinding wheel during tool detection, and to improve the robustness of the data through multi-point contact.

[0092] During the downward feeding of the grinding wheel, the signal acquisition and processing unit records the state signal of the contact tool detection sensor and the Z axis coordinate position at the corresponding time in real time at a high sampling rate, and obtains the initial tool detection data sequence containing the time stamp, sensor state and Z axis coordinate.

[0093] In this embodiment, the specific process of performing the tool detection movement includes:

[0094] Controlling the machine tool Z axis to move quickly to a position close to the contact tool detection sensor at a first feeding speed.

[0095] Controlling the machine tool Z axis to switch to a second feeding speed for slow downward feeding, the second feeding speed being smaller than the first feeding speed.

[0096] While the Z axis is fed down slowly, controlling the X axis or Y axis to perform reciprocating motion in the form of a sine wave or a triangular wave within a preset sweep width range, the sweep width being greater than the width or diameter of the grinding wheel, so as to ensure that the outer circular surface of the grinding wheel can cover the sensing area of the contact tool detection sensor.

[0097] S2: Signal processing and feature extraction are performed on the initial tool setting data sequence, noise interference is removed, valid contact events are identified, and Z-axis contact coordinates corresponding to each valid contact event are extracted to form a Z-axis coordinate set;

[0098] The collected initial tool setting data sequence is filtered to eliminate high-frequency noise interference;

[0099] It should be noted that due to machine vibration and electromagnetic interference, the original sensor signal may contain burrs, and the signal signal-to-noise ratio is improved by sliding average filtering or median filtering algorithm.

[0100] A trigger threshold is set, and when the amplitude of the filtered sensor signal exceeds the trigger threshold, the time is marked as a suspected contact time;

[0101] In this embodiment, the trigger threshold should be higher than the background noise level when the load is zero, and lower than the full-scale output of the sensor, so as to accurately capture the contact event.

[0102] A data segment within a preset time window is intercepted forward and backward with each suspected contact time as the center, and the Z-axis coordinate when the sensor signal reaches the peak value in the data segment is extracted, which is recorded as the candidate contact point coordinate;

[0103] Specifically, the coordinate of the peak value time is extracted to eliminate the position error caused by the rising or falling delay of the signal, and to ensure that the position when the contact is closest is obtained.

[0104] All candidate contact point coordinates are arranged in time sequence to form a Z-axis coordinate set , wherein n is the number of candidate contact points.

[0105] S3: According to the Z-axis coordinate set, the distribution characteristics are obtained, the confidence degree of each candidate contact point as a real tool setting point is calculated, and the abnormal points are removed to obtain an effective coordinate set ;

[0106] The mean value of the Z-axis coordinate set is calculated And the standard deviation ;

[0107] The deviation degree of the i-th candidate contact point From the mean value is calculated as follows:

[0108] ;

[0109] Wherein, The normalized distance of the i-th candidate contact point from the mean value is represented by The absolute value function is represented by

[0110] According to the deviation degree​ Calculate the confidence of each candidate contact point as a real contact point The calculation method is as follows:

[0111] ;

[0112] It should be noted that the confidence obeys the Gaussian distribution law, the smaller the deviation, the higher the confidence of the point, and the larger the deviation, the lower the confidence of the point, which may be due to abnormal points caused by adhesion of foreign matter on the grinding wheel surface or sensor false triggering.

[0113] Pre-set confidence threshold , the candidate contact point is determined as an abnormal point and is rejected, and the candidate contact points with higher confidence are retained to form an effective coordinate set .

[0114] S4: Based on the effective coordinate set, analyze the runout characteristics of the grinding wheel, and calculate the highest point position and average center position of the grinding wheel;

[0115] Perform extreme value analysis on the data in the effective coordinate set , find the maximum value and the minimum value ;

[0116] Calculate the runout of the grinding wheel , the calculation method is as follows:

[0117] ;

[0118] Specifically, the runout reflects the geometric shape error and installation eccentricity of the grinding wheel, which is an important parameter affecting the grinding surface quality.

[0119] According to the effective coordinate set , calculate the average contact position of the grinding wheel , the calculation method is as follows:

[0120] ;

[0121] In the formula, m represents the number of points in the effective coordinate set ; and is the coordinate of the jth effective contact point.

[0122] According to the highest point position of the grinding wheel and the average contact position , calculate the tool correction coefficient α, the calculation method is as follows:

[0123] ;

[0124] In the formula, is a minimum value, preventing the denominator from being zero; a reflects the proportion of the offset of the highest point of the grinding wheel relative to the average position.

[0125] S5: According to the grinding wheel runout characteristics and the preset machining process strategy, the final tool setting coordinates are determined from the contact coordinate set, the actual position of the grinding wheel tip point is calculated according to the final tool setting coordinates and the initial position coordinates of the contact tool setting sensor, and the workpiece coordinate system offset or tool compensation value of the machine tool is automatically updated.

[0126] In the embodiment, the final tool setting coordinates are determined from the contact coordinate set according to the grinding wheel runout parameters and the preset machining process strategy, and specifically include:

[0127] According to the grinding process type, the tool setting strategy is selected;

[0128] It should be noted that for fine grinding, the highest point of the grinding wheel is usually taken as the reference to ensure consistent cutting depth; for rough grinding, the average contact position can be taken as the reference to improve the utilization rate of the grinding wheel.

[0129] If it is a fine grinding mode, the final tool setting coordinates are set ;

[0130] If it is a rough grinding mode, the final tool setting coordinates are set , wherein β is a weight coefficient, and the value range is 0-0.5;

[0131] If the runout exceeds the preset alarm threshold, an alarm signal is generated and the tool setting process is interrupted.

[0132] In the embodiment, the specific process of automatically updating the workpiece coordinate system offset or tool compensation value of the machine tool includes:

[0133] According to the final tool setting coordinates , the actual distance of the grinding wheel bottom surface or outer circle relative to the zero point of the workpiece coordinate system is calculated in combination with the known installation height of the contact tool setting sensor;

[0134] ;

[0135] , wherein D represents the relative distance between the reference point of the grinding wheel and the zero point of the workpiece coordinate system, represents the known installation height of the contact tool setting sensor.

[0136] It can be understood that the sensor installation height is a known constant, and the accurate position of the grinding wheel in the workpiece coordinate system can be obtained by subtracting the height.

[0137] The calculated grinding wheel position data is updated to the tool compensation register or workpiece coordinate system offset, and the automatic tool setting is completed;

[0138] It should be noted that the numerical control system compares the tool setting result with the preset tool setting accuracy tolerance, and if the error exceeds the tolerance range, an alarm is issued to check the grinding wheel or sensor state.

[0139] At this point, the high-precision automatic tool setting of the surface grinder under the condition of grinding wheel rotation and multi-axis linkage of the machine tool is completed.

[0140] Although embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An automatic tool setting system for a surface grinder, characterized in that, include: The machine tool motion mechanism, including the X-axis, Y-axis worktable and Z-axis feed axis, is used to drive the workpiece and the grinding wheel to perform relative motion; The grinding wheel spindle system is used to drive the grinding wheel to rotate at high speed and provide cutting power; A contact-type tool setting sensor is installed on the machine tool worktable to generate a physical trigger signal when the grinding wheel comes into contact with it; The signal acquisition and processing unit is connected to the tool setting sensor and the CNC system. It is used to acquire sensor signals and machine tool axis position coordinate data in real time, and to perform filtering, feature extraction and statistical analysis on the data. The numerical control system is used to control the movement of the machine tool according to the preset program, and to receive the calculation results of the signal acquisition and processing unit to automatically correct the workpiece coordinate system or tool compensation value.

2. The automatic tool setting system for a surface grinder according to claim 1, characterized in that, The contact-type tool setting sensor is a high-precision mechanical trigger probe or an inductive non-contact displacement sensor, and the contact-type tool setting sensor has a protective structure to prevent contamination by coolant and iron filings.

3. A contact-type tool setting and positioning method, employing the automatic tool setting system of the surface grinder as described in claim 1 or 2, characterized in that, Includes the following steps: S1: Controlling the movement of the machine tool and grinding wheel by acquiring the initial tool setting data sequence through a contact-type tool setting sensor; S2: Preprocess the initial tool setting data sequence to extract effective contact signal segments and the corresponding Z-axis coordinate set; S3: Obtain the distribution characteristics based on the Z-axis coordinate set, calculate the confidence level of each candidate contact point as the true tool setting point, and remove outliers to obtain the effective coordinate set. ; S4: Based on the effective coordinate set, analyze the runout characteristics of the grinding wheel and calculate the highest point position and average center position of the grinding wheel; S5: Based on the grinding wheel runout characteristics and the preset machining process strategy, determine the final tool setting coordinates from the contact coordinate set. Based on the final tool setting coordinates and the initial position coordinates of the contact tool setting sensor, calculate the actual position of the grinding wheel tip and automatically update the workpiece coordinate system offset or tool compensation value of the machine tool.

4. The contact-type tool setting and positioning method according to claim 3, characterized in that, The specific steps for controlling the movement of the machine tool and grinding wheel to acquire the initial tool setting data sequence through a contact-type tool setting sensor include: A contact-type tool setting sensor is installed on the worktable of a surface grinder, and the initial position coordinates of the contact-type tool setting sensor in the machine tool coordinate system are obtained. The machine tool spindle is controlled to drive the grinding wheel to rotate at a preset speed, and the X and Y axes of the machine tool are controlled to move the grinding wheel to a preset area above the contact-type tool setting sensor; The tool setting detection motion is executed, the machine tool's Z-axis is controlled to feed downwards, and the machine tool's X-axis or Y-axis is controlled to perform reciprocating micro-sweeping. The trigger signal of the contact tool setting sensor and the corresponding machine tool Z-axis coordinate are collected in real time to form the initial tool setting data sequence.

5. An automatic tool setting system for a surface grinder according to claim 3, characterized in that, The specific process of performing the tool detection motion includes: The machine tool's Z-axis is controlled to move rapidly at the first feed rate to a safe distance position close to the contact-type tool setting sensor; The machine tool's Z-axis is switched to a second feed speed for slow downward feeding, where the second feed speed is less than the first feed speed. While the Z-axis is slowly feeding downwards, the X-axis or Y-axis is controlled to perform reciprocating motion in the form of a sine wave or a triangular wave within a preset sweep width range. The sweep width is greater than the width or diameter of the grinding wheel to ensure that the outer surface of the grinding wheel can cover the sensing area of ​​the contact-type tool setting sensor.

6. The automatic tool setting system for a surface grinder according to claim 3, characterized in that, The specific process of S2 includes: The initial tool setting data sequence was filtered to eliminate high-frequency noise interference; Set a trigger threshold. When the amplitude of the filtered sensor signal exceeds the trigger threshold, mark that moment as a suspected contact moment. Centered on each suspected contact moment, data segments within a preset time window are extracted forward and backward, and the Z-axis coordinates of the sensor signal reaching the peak value within the data segment are extracted and recorded as the coordinates of the candidate contact point. Arrange all candidate contact point coordinates in chronological order to form a Z-axis coordinate set. , where n is the number of candidate contact points.

7. The contact-type tool setting and positioning method according to claim 3, characterized in that, The obtained effective coordinate set The specific process includes: Calculate the mean of the set of Z-axis coordinates and standard deviation ; The i-th candidate contact point degree of deviation from the mean The calculation formula is: ； in, This represents the standardized distance between the i-th candidate contact point and the mean. Represents the absolute value function; According to the degree of deviation Calculate the confidence level of each candidate contact point as the true tool setting point. The calculation formula is: ； Preset reliability threshold ,Will Candidate contact points are identified as outliers and removed, while candidate contact points with higher confidence levels are retained to form a valid coordinate set. .

8. The contact-type tool setting and positioning method according to claim 3, characterized in that, The specific process of S4 is as follows: For the set of valid coordinates Perform extreme value analysis on the data to find the maximum value. and minimum value ; Calculate the runout of the grinding wheel. The calculation formula is: ； Based on the set of valid coordinates Calculate the average contact position of the grinding wheel The calculation method is as follows: ； In the formula, m represents the set of effective coordinates. The number of midpoints; Let J be the coordinates of the j-th effective contact point; Based on the highest point position of the grinding wheel and average contact position Calculate the tool setting correction factor α using the following formula: ； In the formula, To minimize the value and prevent the denominator from being zero; α reflects the offset of the highest point of the grinding wheel relative to the average position.

9. The contact-type tool setting and positioning method according to claim 3, characterized in that, The specific steps of determining the final tool setting coordinates from the contact coordinate set based on the grinding wheel runout parameters and the preset machining process strategy include: Select the tool setting strategy according to the type of grinding process; If it is in fine grinding mode, set the final tool setting coordinates. ; If it is in rough grinding mode, set the final tool setting coordinates. , where β is the weighting coefficient, with a value ranging from 0 to 0.5; If the amount of jumping If the preset alarm threshold is exceeded, an alarm signal will be generated and the tool setting process will be interrupted.

10. A contact-type tool setting and positioning method according to claim 9, characterized in that, The specific process for automatically updating the workpiece coordinate system offset or tool compensation value of the machine tool includes: Based on the final tool setting coordinates Based on the known installation height of the contact-type tool setting sensor, calculate the actual distance between the bottom surface or outer circle of the grinding wheel and the zero point of the workpiece coordinate system; ； Where D represents the relative distance between the grinding wheel reference point and the zero point of the workpiece coordinate system. Indicates the known installation height of the contact-type tool setting sensor; The calculated grinding wheel position data is updated to the tool compensation register or workpiece coordinate system offset to complete automatic tool setting.

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