Through-hole reverse high-precision boring process based on in-situ detection of optical equipment

Abstract

The application discloses a through-hole reverse high-precision boring process based on in-situ detection of an optical device and belongs to the field of high-precision manufacturing. The method comprises the following steps: S1, workpiece clamping and front face boring; S2, white light confocal sensor collecting hole center position; step S3, workpiece reverse; S4, white light confocal sensor detecting precision turntable reverse angle deviation; S5, CNC system automatically correcting tool path and executing reverse face boring; and S6, coaxiality verification. The application realizes continuous machining and in-situ detection of front and reverse faces of a workpiece by integrating an optical detection device, a CNC control unit and a precision turntable. The optical device is a white light confocal sensor, which can acquire hole geometric features and center coordinates in real time. After the workpiece is reversed by 180 degrees through the turntable, the system automatically identifies the reverse hole position and calculates the spatial deviation, the CNC system automatically corrects the tool path according to the detection data, and coaxiality adaptive machining is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of high-precision manufacturing, and relates to a high-precision boring process for a through hole, in particular to a high-precision boring process for a through hole based on in-situ detection of an optical device. BACKGROUND

[0002] In the field of high-precision manufacturing, the machining quality of a through hole has a decisive effect on the assembly performance of a part and the precision of a whole machine. The traditional machining of a through hole usually adopts a "double-side boring" process, that is, one side hole is machined first, and then the other side hole is machined through manual reversing or a turnover fixture. This method has the following technical defects:

[0003] 1) The positioning error of manual reversing is large, resulting in the non-coincidence of the axes of the front and rear holes;

[0004] 2) Offline three-coordinate machine (CMM) detection is required, and a machining closed loop cannot be formed;

[0005] 3) The process efficiency is low, the operation is complex, and automatic production is difficult to achieve.

[0006] The prior art such as CN120002032A discloses a part reversing 180° high-precision coaxial hole boring method, which realizes reverse surface alignment through mechanical reference auxiliary positioning. However, this method still requires manual reversing and contact type probe detection, and cannot realize optical nondestructive detection and real-time feedback. Therefore, at present, there is still a lack of a high-precision through hole machining method which can realize in-situ detection and automatic compensation after reversing 180° on the machine. SUMMARY

[0007] In order to solve the problems of "large reversing positioning error, coaxiality control difficulty, detection lag and compensation delay" in the traditional double-side boring process of a through hole, the application provides a high-precision boring process for a through hole based on in-situ detection of an optical device. The process integrates optical detection and CNC compensation control, realizes in-situ detection, error identification and trajectory compensation after workpiece reversing, significantly improves the coaxiality of a through hole and the consistency of machining, reduces manual operation, and improves the coaxiality of a through hole.

[0008] The purpose of the application is realized by the following technical scheme:

[0009] A high-precision boring process for a through hole based on in-situ detection of an optical device, comprising the following steps:

[0010] Step S1, workpiece clamping and front boring:

[0011] Clamp the workpiece to be machined on the precision rotary table of the precision boring machine. After clamping, bore the front surface of the workpiece. The specific steps are as follows:

[0012] Step S1-1, the workpiece to be processed is clamped on the precision rotary table of the machine tool by a precision clamp, ensuring firm clamping of the workpiece and reliable positioning reference;

[0013] Step S1-2, after clamping is completed, under the control of the CNC program, the target hole on the front face of the workpiece is rough bored and fine bored using a boring tool to achieve the size and surface finish required by the drawing;

[0014] Step S2, white light confocal sensor collects the center position of the orifice:

[0015] The center position of the front orifice processed in step S1 is collected by a white light confocal sensor, and the specific steps are as follows:

[0016] At least three non-collinear points of the front orifice are scanned by the white light confocal sensor, and the center coordinates of the orifice are obtained by fitting calculation;

[0017] Step S3, workpiece reverse:

[0018] The precision rotary table is driven to reverse 180°, and the positioning reference of the workpiece remains unchanged during the reversing process;

[0019] Step S4, white light confocal sensor detects the angle deviation of the precision rotary table after reversing:

[0020] The angle deviation between the actual angle after reversing the precision rotary table and the theoretical 180° position is detected by the white light confocal sensor, and the specific steps are as follows:

[0021] A high-precision ceramic standard ball is installed on the precision rotary table, and the position change of the high-precision ceramic standard ball before and after reversing the precision rotary table is measured by the white light confocal sensor, and then the angle deviation between the actual reversing angle and the theoretical reversing angle is calculated :

[0022]

[0023] In the formula, is the initial position of the highest point of the top of the high-precision ceramic standard ball in the machine tool coordinate system, is the new position of the highest point of the top of the high-precision ceramic standard ball after reversing in the machine tool coordinate system;

[0024] Step S5, CNC system automatically corrects tool path and performs reverse boring:

[0025] The CNC system automatically calculates and corrects the tool path for reverse boring according to the angle deviation measured in step S4, and performs reverse boring on the workpiece according to the corrected path, and the specific steps are as follows:

[0026] Step S5-1, path correction calculation: the CNC system reads the stored front hole center and angle deviation ;

[0027] Step S5-2, center compensation: in theory, after reversing 180°, the front hole center should move to the symmetrical position , but due to the angle deviation , the actual ideal reverse boring center needs to be corrected by a rotation transformation:

[0028]

[0029]

[0030] Step S5-3, generate new path: the CNC system automatically generates or offsets the original reverse boring tool path based on the corrected center coordinates ;

[0031] Step S5-4, execute processing: the system calls the corrected processing program to drive the boring tool to bore the reverse surface of the workpiece;

[0032] Step S6, coaxiality verification:

[0033] After the front and reverse boring are completed, the coaxiality of the through hole is verified.

[0034] Compared with the prior art, the present application has the following advantages:

[0035] The present application realizes continuous processing and in-situ detection of the workpiece front and reverse surfaces by integrating optical detection equipment, a CNC control unit and a precision rotary table. The optical equipment is a white light confocal sensor, which can obtain the aperture geometric features and center coordinates in real time. When the workpiece is reversed 180° by the rotary table, the system automatically identifies the reverse hole position and calculates the spatial deviation, and the CNC system automatically corrects the tool path according to the detection data to realize self-adaptive coaxiality processing. The present application can detect the rotation accuracy of the precision rotary table through the optical equipment and compensate in-situ, avoiding manual secondary clamping during double-sided boring, improving processing efficiency and hole system coaxiality. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a white light confocal sensor for collecting aperture center position;

[0037] Figure 2 is a white light confocal sensor for detecting the reverse angle deviation of the precision rotary table;

[0038] In the figure, 1 is a high-precision ceramic standard ball, 2 is a processed workpiece, 3 is a white light confocal sensor, and 4 is a precision rotary table. DETAILED DESCRIPTION

[0039] The technical solutions of the present application are further described below in conjunction with the drawings, but are not limited thereto, and any modification or equivalent replacement within the spirit and scope of the technical solutions of the present application shall be covered in the protection scope of the present application.

[0040] The present application provides a via reverse high-precision boring process based on in-situ detection of optical equipment, which comprises the following steps:

[0041] Step S1: Clamping the workpiece on the precision rotary table of the precision boring machine, after clamping, boring the front surface of the workpiece.

[0042] Step S2: Collecting the center position of the front surface aperture processed in step S1 by using a white light confocal sensor.

[0043] In this step, the specific method for collecting the center position of the front surface aperture is to scan at least three non-collinear points of the front surface aperture by the white light confocal sensor, and obtain the center coordinates of the aperture by fitting calculation.

[0044] Step S3: Drive the precision rotary table to reverse 180°, and keep the positioning reference of the workpiece unchanged during the reversing process.

[0045] In this step, after the precision rotary table is reversed 180°, the white light confocal sensor is the same set of equipment as in step S2, and its position in the machine tool coordinate system remains unchanged.

[0046] Step S4: Detecting the angle deviation between the actual angle of the precision rotary table after reversing and the theoretical 180° position by using the white light confocal sensor.

[0047] In this step, the specific method for detecting the angle deviation is to install a high-precision ceramic standard ball on the precision rotary table, measure the position change of the high-precision ceramic standard ball before and after the precision rotary table is reversed by the white light confocal sensor, and then calculate the angle deviation between the actual reversing angle and the theoretical reversing angle.

[0048] In this step, the angle deviation The angle deviation is calculated by the following formula:

[0049]

[0050] In the formula, is the initial position of the highest point of the top of the high-precision ceramic standard ball in the machine tool coordinate system, is the new position of the highest point of the top of the high-precision ceramic standard ball in the machine tool coordinate system after reversing.

[0051] Step S5: The CNC system automatically calculates and corrects the tool path for the back boring according to the angle deviation measured in step S4, and performs the back boring on the workpiece according to the corrected path.

[0052] In this step, the correction of the tool path includes compensating the position of the back boring starting point and / or compensating the direction of the boring axis.

[0053] Step S6: After the front and back boring are both completed, the coaxiality of the processed through hole is verified.

[0054] Embodiment:

[0055] Step S1, workpiece clamping and front boring:

[0056] The workpiece to be processed is clamped on the precision rotary table of the machine tool through a precision clamp, ensuring that the workpiece is clamped firmly and the positioning reference is reliable. After clamping is completed, the target hole on the front surface of the workpiece is rough bored and finish bored using a boring tool under the control of the CNC program, achieving the required size and surface finish according to the drawing.

[0057] Step S2, white light confocal sensor collects the hole center position Figure 1 ):

[0058] Sensor positioning: The CNC system of the machine tool controls the spindle to move to a safe position and moves the worktable so that the measuring head of the white light confocal sensor is located directly in front of the theoretical center of the processed hole, 10 mm away from the surface of the workpiece.

[0059] Automatic focusing and coordinate association: The sensor performs the automatic focusing function, accurately finds the focal point position of the upper surface of the workpiece (i.e. the hole end surface), and records the height (Z-axis coordinate) of this position and synchronizes it to the machine tool coordinate system.

[0060] Circular point data collection: In this embodiment, the center is collected using the multi-point fitting method. The CNC system controls the white light confocal sensor to uniformly select 8 measurement points (P1~P8) on the circumference of the hole. For each point, the sensor moves radially inward along the hole, and when the measuring head's light spot suddenly detects the reflection signal of the hole wall from the hole's empty space, the machine tool coordinates of this edge point are recorded . Repeat this process to obtain the accurate coordinates of the 8 points.

[0061] Circle center calculation: The macro program built into the CNC system calls the least squares circle fitting algorithm to fit the 8 points collected. The algorithm calculates the center coordinates and the radius of the circle that best matches these points. The center coordinates of this circle are the measured center position of the front hole, and are stored in system variable #100.

[0062] Step S3, workpiece reverse:

[0063] The precision rotary table (B-axis) drives the workpiece to reverse accurately 180° under the control of CNC instructions (e.g., "B180."). During this process, the workpiece is always fixed on the rotary table, and its positioning reference remains unchanged.

[0064] Step S4, white light confocal sensor detects the reverse angle deviation of the precision rotary table Figure 2 :

[0065] To detect the deviation of the actual angle after reverse from the theoretical 180°, the following operations are performed:

[0066] A high-precision ceramic standard ball is installed in advance as a reference target at the center position of the workpiece being machined.

[0067] Pre-measurement before detection: Before step S1, the white light confocal sensor first scans the highest point of the top of the standard ball to determine its initial position in the machine tool coordinate system .

[0068] Post-reverse measurement: After step S3 is completed, the sensor scans the highest point of the top of the same standard ball again to obtain its new position after reverse .

[0069] Deviation calculation: The macro program of the CNC system calculates the actual reverse angle through the arctangent trigonometric function according to the two sets of coordinates. Specifically, the angle deviation (in units of degrees) can be calculated by the following formula:

[0070]

[0071] The calculated angle deviation is stored in system variable #101. At the same time, the axial runout error of the rotary table can also be evaluated through the change in Z coordinate .

[0072] Step S5, CNC system automatically corrects tool path and performs reverse boring:

[0073] Path correction calculation: The CNC system reads the stored front face hole center and the angle deviation .

[0074] Center compensation: In theory, after reversing 180°, the front face hole center should move to the symmetrical position . However, due to the angle deviation , the actual ideal reverse boring center needs to be corrected through a rotation transformation:

[0075]

[0076]

[0077] Generate new path: CNC system generates a new tool path for the reverse side based on the corrected center coordinates.

[0078] Execute machining: The system calls the corrected machining program and drives the boring tool to machine the reverse side of the workpiece. This process is fully automated and does not require manual intervention for tool setting or program modification.

[0079] Step S6, coaxiality verification:

[0080] After machining is completed, white light confocal sensing can be used to measure the holes on the front and back sides respectively, and two axes are fitted. Finally, the coaxiality of the machined through hole is calculated and verified to see if it meets the design requirements.

[0081] Step S7, result evaluation:

[0082] Evaluate whether the coaxiality of the workpiece hole system meets the machining precision requirements. If the error exceeds the allowed range, adjust the compensation program and repeat the experiment until the requirements are met.​

Claims

1. A via reverse high-precision boring process based on in-situ detection of an optical device, characterized by The process comprises the following steps: Step S1, workpiece clamping and front face boring: Clamp the workpiece to be processed on the precision rotary table of the precision boring machine, and after clamping, bore the front face of the workpiece; Step S2, white light confocal sensor collects the center position of the orifice: Use the white light confocal sensor to collect the center position of the front orifice processed in step S1; Step S3, workpiece reverse: Drive the precision rotary table to reverse 180°, and the workpiece keeps its positioning reference unchanged during the reversing process; Step S4, white light confocal sensor detects the angle deviation of the precision rotary table after reversing: Use the white light confocal sensor to detect the angle deviation between the actual angle after reversing the precision rotary table and the theoretical 180° position, and the specific steps are as follows: A high-precision ceramic standard ball is installed on a precision rotary table, and the position change of the high-precision ceramic standard ball before and after the precision rotary table is reversed is measured by a white light confocal sensor, and then the angle deviation between the actual reversal angle and the theoretical reversal angle is calculated The calculation formula of the angle deviation is In the formula, is the initial position of the top highest point of the high-precision ceramic standard ball in the machine tool coordinate system, is the new position of the top highest point of the high-precision ceramic standard ball after being reversed in the machine tool coordinate system; Step S5, CNC system automatically corrects tool path and performs reverse face boring: According to the angle deviation measured in step S4, the CNC system automatically calculates and corrects the tool path for reverse face boring, and performs reverse face boring on the workpiece according to the corrected path, and the specific steps are as follows: Step S5-1, Path Correction Calculation: The CNC system reads the stored front face bore center and angular deviation ; Step S5-2, center compensation: in theory, after reversing 180°, the front face hole center should move to the symmetric position But due to the angle deviation The actual ideal back face boring center needs to be corrected by a rotation transformation: Step S5-3, generating new path: the CNC system generates a new tool path based on the corrected center coordinates As a reference, automatically generate or offset the original counter boring tool path; Step S5-4, execute processing: the system calls the corrected processing program to drive the boring tool to bore the reverse face of the workpiece; Step S6, coaxiality verification: After the front and reverse face boring is completed, the coaxiality of the processed through hole is verified.

2. The via-reversal high-precision boring process based on in-situ detection of optical equipment according to claim 1, characterized in that The specific steps of step S1 are as follows: Step S1-1, clamp the workpiece to be processed on the precision rotary table of the machine tool through the precision clamp, ensure that the workpiece is clamped firmly, and the positioning reference is reliable; Step S1-2, after clamping, use the boring tool to perform rough boring and fine boring on the target hole of the workpiece under the control of the CNC program, so as to achieve the size and surface finish required by the drawing.

3. The via-reversal high-precision boring process based on in-situ detection of optical equipment according to claim 1, characterized in that The specific steps of step S2 are as follows: Scan at least three non-collinear points of the front orifice through the white light confocal sensor, and obtain the center coordinates of the orifice through fitting calculation.

4. The via-reversal high-precision boring process based on in-situ detection of optical equipment according to claim 1, characterized in that In step S3, after the precision rotary table is reversed 180°, the white light confocal sensor is the same set of equipment as in step S2, and its position in the machine tool coordinate system remains unchanged.

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