An automated production line tray exchange zero-point adaptive system and method

Abstract

The application discloses an automatic production line tray interchanging zero point self-adaptive system and method, and belongs to the technical field of numerical control machining. The method comprises the following steps: S1, measuring the zero point offset of each tray at each machine tool station, generating a corresponding zero point offset calling program and storing the program in the machine tool; S2, establishing a process path for a workpiece in a control system, binding the tray, the target machine tool station and the corresponding zero point offset calling program; S3, when a task is executed, the control system controls the tray to be transported to the target station, and the corresponding zero point offset program is called according to the process path, and the machine tool machining coordinate system is automatically refreshed. According to the application, the zero point data of each "tray-station" combination is pre-stored and accurately called, the positioning error caused by tray interchanging is effectively eliminated, the machining precision is improved to within 0.005 mm, and the safety of the system is ensured through the probe checking and alarm mechanism, so that the precision, flexibility and reliability of the automatic production line are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of CNC machining technology, specifically relating to a zero-point adaptive system and method suitable for automated production lines of high-end precision parts such as aircraft casings. This system and method can automatically adapt to and compensate for positioning errors when pallets are interchanged between different machine tool stations, ensuring high-precision machining requirements. Background Technology

[0002] As the manufacturing industry transforms towards intelligence and automation, automated production lines for complex and precision parts such as aircraft casings are becoming increasingly widespread. These production lines typically employ palletized logistics systems, using automated handling devices (such as stacker cranes) to move pallets and fixtures loaded with workpieces between different processing stations (machine tools) to achieve unmanned and continuous production, significantly improving processing efficiency.

[0003] However, the frequent exchange and repetitive positioning of multiple pallets and fixtures across multiple workstations inevitably leads to cumulative positioning errors. While typical zero-point positioning systems offer a certain level of accuracy, the interchangeability accuracy between pallets and fixtures is typically only 0.01mm–0.02mm. Adding the inherent error of the pallet positioning system itself (approximately 0.005mm), the total final positioning error of the workpiece on the machine tool often exceeds 0.01mm. For high-precision products such as aircraft housings requiring five-axis simultaneous machining, the required datum positioning accuracy is typically within 0.01mm. The positioning accuracy of existing automated production lines is insufficient to meet the machining requirements of such products, becoming a technological bottleneck restricting the automated production of high-precision products. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an automated production line pallet interchange zero-point adaptive system and method to solve the problem of insufficient processing accuracy of high-precision products caused by positioning errors introduced by pallet interchange in the prior art.

[0005] To achieve the above objectives, according to a first aspect of the present invention, an adaptive zero-point method for pallet interchange on an automated production line is proposed, comprising the following steps: S1. Establish a pallet-machine tool station zero-point offset database: For each pallet used on the production line, measure and record the zero-point offset at each possible machine tool station it can reach, and bind the zero-point offset data with a specific "pallet-machine tool station" combination to generate a corresponding zero-point offset calling program, which is then stored in the CNC system of the corresponding machine tool. S2. Constructing the process path binding relationship of the digital control system: In the digital control system of the production line, a process path is established for each workpiece to be processed. The process path includes at least: the pallet identifier that carries the workpiece, the target machine tool and its station identifier corresponding to the process, and the zero-point offset call program generated in step S1 that corresponds to the "pallet-machine tool station" combination. S3. Automatic zero-point offset call during machining task execution: When the production line executes a machining task, the control system controls the transport system to transport the designated pallet to the designated workstation of the target machine tool according to the preset process path. After the pallet is placed, the control system sends an instruction to the machine tool through the communication protocol according to the binding relationship of the process path, calls and executes the pre-stored zero-point offset call program corresponding to the "pallet-machine tool workstation" combination, refreshes the machining coordinate system of the machine tool, and realizes automatic zero-point adaptation.

[0006] According to a second aspect of the present invention, an automated production line pallet interchange zero-point adaptive system is provided, comprising: A control system is used to execute steps S2 and S3 of the above method; A handling system, controlled by the control system, is used to perform pallet transport; At least one machine tool has at least one machining station, and the CNC system of the machine tool stores the zero-point offset calling program generated by the above method; The control system is connected to the machine tool via a communication protocol and is used to call the corresponding zero-point offset calling program after the pallet is placed.

[0007] Furthermore, in step S1, measuring and recording zero-point offset data on the machine tool specifically includes: loading a pallet with a fixture onto a designated station of the target machine tool via a transport system; performing zero-point measurement on the loaded workpiece on the machine tool to obtain a precise offset value relative to the machine tool reference point; and using the variable function of the machine tool's CNC system, writing the measured offset value into a subroutine that can be called by the main program, naming it according to a rule that includes pallet identification and station identification, and storing it in the machine tool's system.

[0008] Furthermore, in step S2, the process path binding relationship of the digital control system is constructed, specifically including: digitally modeling entities such as pallets, machine tools, workstations, fixtures, and workpieces using modeling technology in the control system; establishing data tables for each entity using a relational database, wherein the pallet data table includes at least fields such as pallet number, current process, target workstation, and bound zero-point offset program name; and configuring and binding the pallets, fixtures, workpieces, target machine tools and workstations involved in the process path, as well as the corresponding zero-point offset programs, in the process management module to form a complete process path.

[0009] Furthermore, in step S3, the automatic invocation of zero-point offset during the execution of the machining task specifically includes: the control system monitoring the status of each pallet in real time and determining the next target machine tool and station according to the preset process path; the control system controlling the transport system to transport the pallet to the designated station of the target machine tool and completing the placement and locking; the control system obtaining the corresponding zero-point offset program name according to the binding relationship of the process path and sending instructions to the target machine tool through an industrial Ethernet communication protocol (such as OPC UA); the CNC system of the target machine tool receiving the instructions, invoking and executing the zero-point offset program, and automatically updating the values ​​of its machining coordinate system (such as G54, G55, etc.).

[0010] Furthermore, after step S3, there is also a precision verification and alarm step: after calling the zero-point offset program, the machine tool automatically runs a verification program, using the probe installed on the machine tool to measure the key reference points on the workpiece; the measured actual coordinate values ​​are compared with the theoretical values ​​set by the zero-point offset program. If the deviation exceeds the preset safety threshold, the system triggers an alarm and suspends the machining process to prompt manual intervention and inspection.

[0011] Compared with the prior art, the present invention has the following beneficial effects: Significantly improves machining accuracy: By "tailor-made" zero-point offset data for each pallet at each workstation and achieving automatic and precise recall, the repeated positioning error caused by pallet and fixture interchange is effectively eliminated, and the overall positioning accuracy can be improved to within 0.005mm, fully meeting the machining requirements of high-precision five-axis products.

[0012] Achieving flexible and automated production: This method allows a single production line to process multiple different product models without the need for tedious manual alignment and tool setting during each production changeover, greatly improving the flexibility, efficiency, and automation level of the production line.

[0013] Enhancing system reliability and safety: Through a multi-layered protection mechanism of "control system binding - machine tool system execution - probe verification feedback," closed-loop control from data management to physical execution is achieved. Precision verification and out-of-tolerance alarms are performed before processing, effectively preventing scrap and equipment accidents caused by program call errors, zero-point data errors, or workpiece clamping errors, significantly improving the operational safety of automated production lines. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a technical architecture diagram of an automated production line in an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the production line layout and zero-point positioning system structure in an embodiment of the present invention.

[0017] Figure 3 This is a flowchart of the control system calling the zero-bias program in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0020] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0022] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0024] Example This embodiment uses an automated production line for aircraft housings, consisting of four five-axis machine tools with Siemens 840D SL CNC systems, as an example. This production line processes three different models of housings: GJ1, GJ2, and GJ3. The production line layout is as follows... Figure 1 and Figure 2 As shown, it mainly includes: a central control system (MES), a handling system (stall crane), a loading area, and four machine tools (each machine tool is equipped with two zero-point positioning stations). The zero-point positioning system structure is as follows. Figure 2 As shown, from bottom to top, they are: machine tool zero-point positioning system, interchangeable pallets and fixtures, and product parts.

[0025] 1. Establish a pallet-machine tool station zero-point offset database (corresponding to step S1) 1.1 Pallet and workstation number To facilitate management, pallets, machine tools, and workstations on the production line are uniformly numbered. For example: Pallets: #10, #11, #12 Machine tools: Machine tool 1, Machine tool 2, Machine tool 3, Machine tool 4 Machine tool station: Each machine tool contains two zero-point positioning systems, No. 1 and No. 2.

[0026] 1.2 Measure and generate the zero-point offset subroutine (taking pallet #10, product GJ1, and station #1 of machine tool 1 as an example) Step 1: The operator fixes the J1 clamp on the 10# pallet in the loading area and installs the GJ1 product onto the J1 clamp.

[0027] Step Two: The control system directs the stacker crane to transport pallet #10 to the zero-point positioning system of machine tool 1 and insert it into the machine tool. Step 3: On machine tool 1, use a probe or tool setter to precisely align the GJ1 product and determine its zero-point offset value in the machine tool coordinate system. For example, the measured data for the first coordinate system G54 and the second coordinate system G55 are as follows: G54: X 0.05, Y 245.32, Z 0.08, A 0, B 0.425 G55: X -0.05, Y 245.32, Z -0.08, A 0, B 180.425 Step 4: Using the variable function of the Siemens system, write the above data into a subroutine and name it 10_1.SPF according to the rule "pallet number_station number.SPF", and store it in the system of machine tool 1. The subroutine content is as follows: text Subroutine 10_1.SPF $P_UIFR[1, X, TR] = 0.05; G54 X-axis coordinate $P_UIFR[1, Y, TR] = 245.32; G54 Y-axis coordinate $P_UIFR[1, Z, TR] = 0.08; G54 Z-axis coordinate $P_UIFR[1, A, TR]=0; G54 A-axis coordinates $P_UIFR[1, B, TR]=0.425; G54 B-axis coordinate $P_UIFR[2, X, TR] = -0.05; G55 X-axis coordinate $P_UIFR[2, Y, TR] = 245.32; G55 Y-axis coordinate $P_UIFR[2, Z, TR] = -0.08; G55 Z-axis coordinate $P_UIFR[2, A, TR]=0; G55 A-axis coordinate $P_UIFR[2, B, TR]=180.425; G55 B-axis coordinate M17 Step 5: Repeat the above steps to generate the corresponding zero-point offset subroutine for all pallet-station combinations. For example, pallet #11 generates 11_2.SPF at station #2 of machine tool 1, pallet #12 generates 12_1.SPF at station #1 of machine tool 1, and so on.

[0028] 2. Establish process path binding relationships for the digital control system (corresponding to step S2) In the central control system, a process path is established for each product model to be processed. Operators then configure and bind the necessary settings in the process management interface as follows: The process path for product GJ1 is as follows: Workpiece GJ1 -> Fixture J1 -> Pallet 10# -> Target Equipment: Machine Tool 1 -> Target Station: Zero-point Positioning System No. 1 -> Zero-point Execution File: 10_1.SPF The process path for product GJ2 is as follows: Workpiece GJ2 -> Fixture J2 -> Pallet 11# -> Target equipment: Machine Tool 1 -> Target station: Zero-point positioning system No. 2 -> Zero-point execution file: 11_2.SPF The process path for product GJ3 is as follows: Workpiece GJ3 -> Fixture J3 -> Pallet 12# -> Target Equipment: Machine Tool 1 -> Target Station: Zero-point Positioning System No. 1 -> Zero-point Execution File: 12_1.SPF The management system stores these binding relationships in a relational database as the basis for subsequent automated execution.

[0029] 3. Automatically call zero-point offset when executing machining tasks (corresponding to step S3 and verification steps). After the operator clamps the GJ1, GJ2, and GJ3 products in the loading area, they issue a mixed processing command to the control system. The control system then begins automated scheduling, and the process is as follows: Figure 3 As shown: Step 1: The control system monitors the status of each pallet in real time through the OPC UA protocol and finds that pallet #10 (loaded with GJ1) is ready.

[0030] Step 2: The system queries the database and determines the next target equipment as "station 1 of machine tool 1" based on the process path of pallet #10.

[0031] Step 3: The system queries the status of station 1 of machine tool 1. After confirming that it is idle, it sends an instruction to the stacker crane via TCP / IP protocol to transport pallet #10 to the target station and complete the placement and locking.

[0032] Step 4: After the pallet is placed, the control system sends an instruction to machine tool 1 via the OPC UA protocol based on the information bound in the process path, requiring it to call and execute subroutine 10_1.SPF.

[0033] Step 5: The CNC system of machine tool 1 receives the instruction and executes the 10_1.SPF subroutine. After execution, the G54 and G55 coordinate systems of machine tool 1 are refreshed to match the zero-point offset of the GJ1 product on pallet #10.

[0034] Step Six (Accuracy Verification): After zero-point refresh, the machining program of machine tool 1 automatically calls the probe verification program to measure key points of the workpiece and verify the accuracy of the zero-point data. An example verification program snippet is as follows: text ...Automatic measurement cycle of the probe... Compare the measurement results with the set values ​​to check the X-axis deviation of G54. WHILE $P_UIFR[1, X, FI]>0.01 DO MSG(“X-axis positive deviation out of tolerance”) RETRY WHILE $P_UIFR[1, X, FI] <- 0.01 DO MSG(“X-axis negative deviation out of tolerance”) RETRY ...Perform similar checks on other axes... If the deviation of any axis exceeds the threshold of 0.01mm, the system will pause and issue an alarm, prompting manual intervention. If the verification passes, the formal machining program will begin.

[0035] Process loop: While GJ1 is being processed on machine tool 1, the control system can continue to schedule pallet #11 (GJ2) to station #2 on machine tool 1, or pallet #12 (GJ3) to machine tool 2, and so on. Regardless of which pallet enters which machine tool and which station, the control system will precisely call the corresponding zero-point offset subroutines (such as 11_2.SPF, 12_1.SPF, etc.) according to the pre-generated process path, ensuring that each product can obtain a machine tool machining coordinate system that precisely matches its current physical position.

[0036] Through the above methods, the production line achieves fully automated, high-precision zero-point adaptive operation for different products and pallets at different workstations, successfully solving the problems raised in the background technology.

[0037] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A zero-point adaptive method for pallet interchange in an automated production line, the production line comprising a control system, a handling system, and one or more machine tools having at least one processing station, characterized in that, The method includes the following steps: S1. Establish a pallet-machine tool station zero-point offset database: For each pallet used on the production line, the zero-point offset is measured and recorded at each machine tool station it may reach. The zero-point offset data is then bound to a specific "pallet-machine tool station" combination to generate a corresponding zero-point offset calling program, which is stored in the CNC system of the corresponding machine tool. S2. Constructing the process path binding relationship of the digital control system: In the digital control system of the production line, a process path is established for each workpiece to be processed. The process path includes at least: the pallet identifier that carries the workpiece, the target machine tool and its station identifier corresponding to the process, and the zero-point offset call program generated in step S1 that corresponds to the "pallet-machine tool station" combination. S3. Automatically call zero-point offset when executing machining tasks: When the production line performs a processing task, the control system controls the transport system to transport the designated pallet to the designated workstation of the target machine tool according to the preset process path. After the pallet is placed, the control system sends an instruction to the machine tool through the communication protocol according to the binding relationship of the process path, calls and executes the pre-stored zero-point offset call program corresponding to the "pallet-machine tool workstation" combination, refreshes the machining coordinate system of the machine tool, and realizes automatic zero-point adaptation.

2. The automated production line pallet interchange zero-point adaptive method according to claim 1, characterized in that, In step S1, measuring and recording the zero-point offset data on the machine tool specifically includes the following sub-steps: S11. Load the pallet with clamps to the designated station of the target machine tool through the handling system; S12. Perform zero-point measurement on the loaded workpiece on the machine tool to obtain the precise offset value relative to the machine tool reference point; S13. Using the variable function of the machine tool CNC system, the measured offset value is written into a subroutine that can be called by the main program, and named according to the rules including pallet identifier and station identifier, and stored in the system of the machine tool.

3. The automated production line pallet interchange zero-point adaptive method according to claim 2, characterized in that, In step S13, the naming rule for the zero-point offset calling program is "pallet number_machine station number" to facilitate identification and calling by the control system.

4. The automated production line pallet interchange zero-point adaptive method according to claim 1, characterized in that, In step S2, constructing the process path binding relationship of the digital control system specifically includes the following sub-steps: S21. In the control system, modeling technology is used to digitally model the entities of pallets, machine tools, workstations, fixtures, and workpieces. S22. Use a relational database to create data tables for each entity, where the pallet data table must contain at least the fields of pallet number, current process, target workstation, and binding zero-point offset program name; S23. In the process management module, the pallets, fixtures, workpieces, target machine tools and workstations involved in the process path, as well as the corresponding zero-point offset programs, are configured and bound to form a complete process path.

5. The automated production line pallet interchange zero-point adaptive method according to claim 1, characterized in that, In step S3, the zero-point offset is automatically invoked when the machining task is executed, which specifically includes the following sub-steps: S31. The control system monitors the status of each pallet in real time and determines the next target machine tool and workstation according to the preset process path. S32. The control system controls the handling system to transport the pallet to the designated workstation of the target machine tool and complete the placement and locking; S33. The control system obtains the corresponding zero-point offset program name based on the binding relationship of the process path, and sends a call command to the target machine tool through the industrial Ethernet communication protocol. S34. The CNC system of the target machine tool receives the instruction, calls and executes the zero-point offset program, and automatically updates the values ​​of its machining coordinate system.

6. The automated production line pallet interchange zero-point adaptive method according to claim 5, characterized in that, The industrial Ethernet communication protocol is the OPC UA protocol.

7. The automated production line pallet interchange zero-point adaptive method according to claim 1, characterized in that, Following step S3, a precision verification and alarm step S4 is also included: S41. After calling the zero-point offset program, the machine tool automatically runs a verification program, using the probe installed on the machine tool to measure the key reference points on the workpiece. S42. Compare the measured actual coordinate values ​​with the theoretical values ​​set by the zero-point offset program. If the deviation exceeds the preset safety threshold, the system will trigger an alarm and suspend the processing flow.

8. A zero-point adaptive system for pallet interchange on an automated production line, characterized in that, include: A control system for performing steps S2 and S3 of the method as described in any one of claims 1-7; A handling system, controlled by the control system, is used to perform pallet transport; At least one machine tool having at least one machining station, wherein the CNC system of the machine tool stores a zero-point offset calling program generated by the method as described in any one of claims 1-7; The control system is connected to the machine tool via a communication protocol and is used to call the corresponding zero-point offset calling program after the pallet is placed.

9. The automated production line pallet interchange zero-point adaptive system according to claim 8, characterized in that, The production line is an automated production line for aircraft casings, and the machine tool is a five-axis CNC machine tool.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the automated production line pallet interchange zero-point adaptive method as described in any one of claims 1 to 7.

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