A collision protection method based on PLC double-turret machine tool

Abstract

The present invention belongs to the field of CNC safety protection for dual-turret machine tools and provides a collision avoidance protection method for dual-turret machine tools based on a programmable logic controller (PLC). The CNC machine tool involved in the present invention is equipped with a position measurement feedback encoder or grating ruler, which can determine the real-time position of the machine tool's CNC axes. The tool turret moving axis also uses a CNC servo axis. The position of the machine tool's coordinate axis can be read by the PLC, and the spacing between the two tool turrets is calculated using a formula. This spacing is then compared with the minimum and maximum allowable spacing between the two tool turrets. When the minimum or maximum spacing is exceeded, the tool turret axis is stopped and the system issues an alarm to alert the user. The collision avoidance protection method of the present invention provides dual hardware and software protection for the dual-turret CNC machine tool. Even if the hardware protection fails, the software protection remains in effect, effectively enhancing the safety and reliability of the machine tool.

Description

Technical Field

[0001] The invention belongs to the field of digital control safety protection of double-turret machine tools, and in particular relates to an anti-collision protection method for double-turret machine tools based on a PLC. Background Art

[0002] Dual-turret CNC machine tools feature separate tool turret slides that move linearly on the same guide rail. Due to mechanical interference, the two tool turrets can collide, creating a risk of collision. Therefore, hardware limit switches are installed on both tool turrets to prevent collisions. When the two tool turrets approach, they first hit the limit switch, halting movement of the two axes in the approaching direction to prevent a collision. However, if the switch or anti-collision bracket is damaged, this protection fails, potentially leading to a tool turret collision, potentially damaging mechanical components and compromising machine accuracy, resulting in time-consuming repairs and adjustments. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and propose an anti-collision protection method for a PLC-based double-turret machine tool, which provides dual protection of hardware and software for the double-turret CNC machine tool. Even if the hardware protection fails, the software protection is still effective, thereby enhancing the safety and reliability of the machine tool.

[0004] In order to achieve the above technical objectives, the protection scheme provided by the present invention is as follows.

[0005] The CNC machine tool involved in this invention is equipped with a position measurement feedback encoder or grating ruler, which can determine the real-time position of the machine's CNC axes. The tool holder's moving axis uses a CNC servo axis. This allows the PLC to read the position of the machine's coordinate axes, calculate the spacing between the two tool holders using a formula, and compare it with the minimum and maximum allowable spacing between the two tool holders. If the minimum or maximum spacing is exceeded, the tool holder axis movement is stopped and the system issues an alarm to alert the user. Furthermore, to accommodate different types of machine tools and facilitate debugging by installers, a software protection settings interface has been developed within the CNC system's operating software interface.

[0006] CNC machine tool tool holder type settings, the types are as follows:

[0007] Ⅰ. Tool holder 1 in the same direction is in the positive direction of tool holder 2:

[0008] The positive and negative movement directions of the two tool holders are consistent, and tool holder 1 is in the positive direction of tool holder 2. It is mostly used for the Y axis of double tool holder milling machines and the Z axis of double tool holder horizontal lathes.

[0009] Ⅱ. Tool holder 1 in the same direction is in the negative direction of tool holder 2:

[0010] The positive and negative movement directions of the two tool holders are consistent, and tool holder 1 is in the negative direction of tool holder 2. It is mostly used for the Y axis of double tool holder milling machines and the Z axis of double tool holder horizontal lathes.

[0011] Ⅲ. Reverse zero point is at the center:

[0012] The two tool rests move in opposite directions, and the zero points of both tool rest axes are set at the center. This is mostly used in double-rest turning-milling machines or ZH series machines.

[0013] IV. Reverse zero point at both ends:

[0014] The two tool holders move in opposite directions, and the zero points of the two tool holder axes are set at the end points on the edges of their respective work tables.

[0015] Specifically, the present invention is based on the anti-collision protection method of the PLC double-turret machine tool, comprising the following steps:

[0016] (1) Data measurement of the same direction tool holder 1 in the negative direction of tool holder 2

[0017] (1-1) First, move the two tool holders of the machine tool to the respective zero points where they are to be set. Set the zero points. The coordinates displayed on the machine tool coordinate system are 0.000.

[0018] (1-2) Mark the lower reference point of tool holder 1;

[0019] (1-3) Tool holder 1 moves away from the reference point mark in the negative direction, and then tool holder 2 moves negatively to the mark made by tool holder 1. At this time, the coordinate value P2 of tool holder 2 in the machine tool coordinate system is the zero point distance P0 = P2 between the two tool holders;

[0020] (1-4) Stop tool holder 2 at the zero point, then open tool holder 1 to the minimum distance between the two tool holders. At this time, record the coordinate value P of tool holder 1 in the machine tool coordinate system. 1min , then the minimum distance P allowed between the two tool holders min =ABS(P 1min )+P0;

[0021] (1-5) Open tool post 1 in the negative direction and tool post 2 in the positive direction to the maximum position allowed by the two tool posts. At this time, record the coordinate values P of the two tool posts in the machine tool coordinate system. 1max and P 2max , then the maximum distance allowed between the two tool holders is

[0022] P max =ABS(P 1max )+ABS(P 2max )+P0;

[0023] (1-6) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =ABS(PT2 -P T1 )+P0, and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max ;

[0024] When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes;

[0025] When P T ≥P max Trigger the alarm of the maximum allowable distance between the two tool holders and lock the corresponding movement directions of the two axes;

[0026] (2) Data measurement of the same direction tool holder 1 in the positive direction of tool holder 2

[0027] (2-1) First, move the two tool holders of the machine tool to the respective zero points where they are to be set. Set the zero points. The coordinates displayed on the machine tool coordinate system are 0.000.

[0028] (2-2) Mark the lower reference point of tool holder 2;

[0029] (2-3) Tool holder 2 moves away from the reference point mark in the negative direction, and then tool holder 1 moves negatively to the mark made by tool holder 2. At this time, the coordinate value P1 of tool holder 1 in the machine tool coordinate system is the zero point distance P0 = P1 between the two tool holders;

[0030] (2-4) Stop tool holder 1 at the zero point, then move tool holder 2 to the minimum distance between the two tool holders. At this time, record the coordinate value P of tool holder 2 in the machine tool coordinate system. 2min , then the minimum distance P allowed between the two tool holders min =ABS(P 2min )+P0;

[0031] (2-5) Open tool post 1 in the positive direction and tool post 2 in the negative direction to the maximum position allowed by the two tool posts. At this time, record the coordinate values P of the two tool posts in the machine tool coordinate system. 1max and P 2max , then the maximum distance allowed between the two tool holders is

[0032] P max =ABS(P 1max )+ABS(P 2max )+P0;

[0033] (2-6) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =ABS(PT1 -P T2 )+P0, and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max ;

[0034] When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes;

[0035] When P T ≥P max Trigger the alarm of the maximum allowable distance between the two tool holders and lock the corresponding movement directions of the two axes;

[0036] (3) Data measurement with reverse zero point at the center

[0037] (3-1) Move the two tool holders of the machine tool to the center point and set the zero point. The coordinate displayed by the machine tool coordinate system is 0.000, and the zero point distance between the two tool holders is P0 = 0.

[0038] (3-2) Move tool post 1 to the zero position, and then move tool post 2 to the minimum position allowed by the machine. At this time, record the coordinate P of tool post 2 in the machine coordinate system. 2min , then the minimum distance P allowed between the two tool holders min =ABS(P 2min );

[0039] (3-3) Open the two tool holders to their respective extreme positions. At this time, record the coordinates P of tool holder 1 and tool holder 2 in the machine tool coordinate system. 1max and P 2max , then the maximum allowable distance P between the two tool holders is max =ABS(P 1max +P 2max );

[0040] (3-4) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =ABS(P T1 +P T2 ), and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max ;

[0041] When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes;

[0042] When P T ≥P max Trigger the alarm of the maximum allowable distance between the two tool holders and lock the corresponding movement directions of the two axes;

[0043] (4) Data measurement with reverse zero point at both ends

[0044] (4-1) First, move the two tool holders of the machine tool to the respective zero points where they are to be set. Set the zero points. The coordinates displayed on the machine tool coordinate system are 0.000.

[0045] (4-2) Mark the reference point at the center;

[0046] (4-3) Open tool holder 1 and tool holder 2 to the reference point marks respectively, and record the coordinate value P1 of tool holder 1 and the coordinate value P2 of tool holder 2 in the machine tool coordinate system respectively. The zero point distance P0 of the two tool holders is P0 = ABS(P1 + P2);

[0047] (4-3) Move tool holder 1 and tool holder 2 to the minimum position allowed by the machine, and record the coordinate value P of tool holder 1 in the machine coordinate system. 1min and the coordinate value P of tool holder 2 2min , then the minimum distance allowed between the two tool holders is

[0048] P min =P0-ABS(P 1min +P 2min );

[0049] (4-4) Open the two tool holders to their respective limit positions. At this time, record the coordinates P of tool holder 1 and tool holder 2 in the machine tool coordinate system. 1max and P 2max , then the maximum allowable distance P between the two tool holders is max =P0+ABS(P 1max +P 2max );

[0050] (4-5) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =P0+P T1 +P T2 , and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max

[0051] When P T ≤P minTrigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes;

[0052] When P T ≥P max The maximum allowable distance between the two tool holders is triggered, and the corresponding movement directions of the two axes are locked.

[0053] In the above technical solution, the movement mode of the servo motor of the tool holder shaft is a linear axis.

[0054] The invention is based on a PLC-based anti-collision protection method for a double-turret machine tool. The invention is simple to use and low in cost. The invention utilizes the machine tool's own measurement system and PLC to perform real-time calculation and comparison. The method of the invention provides dual anti-collision protection for the double-turret machine tool, thereby greatly improving the reliability and safety of the machine tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of the method of the present invention in which the two tool holders move in the same direction and tool holder 1 is in the negative direction of tool holder 2.

[0056] Figure 2 This is a schematic diagram of the method of the present invention in which the two tool holders move in the same direction, with tool holder 1 in the forward direction of tool holder 2.

[0057] Figure 3 This is a schematic diagram of the method of the present invention in which the two tool holders move in opposite directions and the zero points of tool holder 1 and tool holder 2 are at the center.

[0058] Figure 4 This is a schematic diagram showing that the double tool holders move in opposite directions in the method of the present invention, with the zero points of tool holder 1 and tool holder 2 being at both ends. DETAILED DESCRIPTION

[0059] To facilitate understanding of the present invention, embodiments of the present invention are further described below in conjunction with the accompanying drawings and examples. The accompanying drawings provide an embodiment of the present invention. It should be understood that this embodiment is intended only to illustrate the present invention and is not intended to limit the present invention. The purpose of providing this embodiment is to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0060] An embodiment of the present invention provides an anti-collision protection method for a PLC-based dual-turret machine tool. The method involves a CNC machine tool equipped with a position measurement feedback encoder or a grating ruler for obtaining the real-time position of a CNC axis of the machine tool. The tool turret moving axis adopts a CNC servo axis, and the servo motor of the tool turret axis moves in a linear axis mode. The method includes the following steps:

[0061] (1) The data of the same direction tool holder 1 is measured in the negative direction of tool holder 2, such as Figure 1 shown

[0062] (1-1) First, move the two tool holders of the machine tool to the respective zero points where they are to be set. Set the zero points. The coordinates displayed on the machine tool coordinate system are 0.000.

[0063] (1-2) Mark the lower reference point of tool holder 1;

[0064] (1-3) Tool holder 1 moves away from the reference point mark in the negative direction, and then tool holder 2 moves negatively to the mark made by tool holder 1. At this time, the coordinate value P2 of tool holder 2 in the machine tool coordinate system is the zero point distance P0 = P2 between the two tool holders;

[0065] (1-4) Stop tool holder 2 at the zero point, then open tool holder 1 to the minimum distance between the two tool holders. At this time, record the coordinate value P of tool holder 1 in the machine tool coordinate system. 1min , then the minimum distance P allowed between the two tool holders min =ABS(P 1min )+P0;

[0066] (1-5) Open tool post 1 in the negative direction and tool post 2 in the positive direction to the maximum position allowed by the two tool posts. At this time, record the coordinate values P of the two tool posts in the machine tool coordinate system. 1max and P 2max , then the maximum distance allowed between the two tool holders is

[0067] P max =ABS(P 1max )+ABS(P 2max )+P0;

[0068] (1-6) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =ABS(P T2 -P T1 )+P0, and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max ;

[0069] When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes;

[0070] When P T ≥P max Trigger the alarm of the maximum allowable distance between the two tool holders and lock the corresponding movement directions of the two axes;

[0071] (2) The data of the same direction tool holder 1 in the positive direction of tool holder 2 is measured, such as Figure 2 shown

[0072] (2-1) First, move the two tool holders of the machine tool to the respective zero points where they are to be set. Set the zero points. The coordinates displayed on the machine tool coordinate system are 0.000.

[0073] (2-2) Mark the lower reference point of tool holder 2;

[0074] (2-3) Tool holder 2 moves away from the reference point mark in the negative direction, and then tool holder 1 moves negatively to the mark made by tool holder 2. At this time, the coordinate value P1 of tool holder 1 in the machine tool coordinate system is the zero point distance P0 = P1 between the two tool holders;

[0075] (2-4) Stop tool holder 1 at the zero point, then move tool holder 2 to the minimum distance between the two tool holders. At this time, record the coordinate value P of tool holder 2 in the machine tool coordinate system. 2min , then the minimum distance P allowed between the two tool holders min =ABS(P 2min )+P0;

[0076] (2-5) Open tool post 1 in the positive direction and tool post 2 in the negative direction to the maximum position allowed by the two tool posts. At this time, record the coordinate values P of the two tool posts in the machine tool coordinate system. 1max and P 2max , then the maximum distance allowed between the two tool holders is

[0077] P max =ABS(P 1max )+ABS(P 2max )+P0;

[0078] (2-6) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =ABS(P T1 -P T2 )+P0, and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max ;

[0079] When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes;

[0080] When P T ≥P max Trigger the alarm of the maximum allowable distance between the two tool holders and lock the corresponding movement directions of the two axes;

[0081] (3) Data measurement with reverse zero point at the center, such as Figure 3 shown

[0082] (3-1) Move the two tool holders of the machine tool to the center point and set the zero point. The coordinate displayed by the machine tool coordinate system is 0.000, and the zero point distance between the two tool holders is P0 = 0.

[0083] (3-2) Move tool post 1 to the zero position, and then move tool post 2 to the minimum position allowed by the machine. At this time, record the coordinate P of tool post 2 in the machine coordinate system. 2min , then the minimum distance P allowed between the two tool holders min =ABS(P 2min );

[0084] (3-3) Open the two tool holders to their respective extreme positions. At this time, record the coordinates P of tool holder 1 and tool holder 2 in the machine tool coordinate system. 1max and P 2max , then the maximum allowable distance P between the two tool holders is max =ABS(P 1max +P 2max );

[0085] (3-4) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =ABS(P T1 +P T2 ), and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max ;

[0086] When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes;

[0087] When P T ≥P max Trigger the alarm of the maximum allowable distance between the two tool holders and lock the corresponding movement directions of the two axes;

[0088] (4) Data measurement with reverse zero points at both ends, such as Figure 4 shown

[0089] (4-1) First, move the two tool holders of the machine tool to the respective zero points where they are to be set. Set the zero points. The coordinates displayed on the machine tool coordinate system are 0.000.

[0090] (4-2) Mark the reference point at the center;

[0091] (4-3) Open tool holder 1 and tool holder 2 to the reference point marks respectively, and record the coordinate value P1 of tool holder 1 and the coordinate value P2 of tool holder 2 in the machine tool coordinate system respectively. The zero point distance P0 of the two tool holders is P0 = ABS(P1 + P2);

[0092] (4-3) Move tool holder 1 and tool holder 2 to the minimum position allowed by the machine, and record the coordinate value P of tool holder 1 in the machine coordinate system. 1min and the coordinate value P of tool holder 2 2min , then the minimum distance allowed between the two tool holders is

[0093] P min =P0-ABS(P 1min +P 2min );

[0094] (4-4) Open the two tool holders to their respective limit positions. At this time, record the coordinates P of tool holder 1 and tool holder 2 in the machine tool coordinate system. 1max and P 2max , then the maximum allowable distance P between the two tool holders is max =P0+ABS(P 1max +P 2max );

[0095] (4-5) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =P0+P T1 +P T2 , and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max

[0096] When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes;

[0097] When P T ≥P max The maximum allowable distance between the two tool holders is triggered, and the corresponding movement directions of the two axes are locked.

[0098] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0099] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and can be modified in many ways. Any simple modifications, equivalent variations, and modifications to the above embodiments based on the technical essence of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A collision protection method based on a PLC double-turret machine tool, characterized in that The method involves a CNC machine tool with a position measurement feedback encoder or a grating ruler for obtaining the real-time position of the CNC axis of the machine tool. The tool holder moving axis adopts a CNC servo axis. The method includes the following steps: (1) Data measurement of the same direction tool holder 1 in the negative direction of tool holder 2 (1-1) First, move the two tool holders of the machine tool to the respective zero points where they are to be set. Set the zero points. The coordinates displayed on the machine tool coordinate system are 0.

000. (1-2) Mark the lower reference point of tool holder 1; (1-3) Tool holder 1 moves away from the reference point mark in the negative direction, and then tool holder 2 moves negatively to the mark made by tool holder 1. At this time, the coordinate value P2 of tool holder 2 in the machine tool coordinate system is the zero point distance P0 = P2 between the two tool holders; (1-4) Stop tool holder 2 at the zero point, then open tool holder 1 to the minimum distance between the two tool holders. At this time, record the coordinate value P of tool holder 1 in the machine tool coordinate system. 1min , then the minimum distance P allowed between the two tool holders min =ABS(P 1min )+P0; (1-5) Open tool post 1 in the negative direction and tool post 2 in the positive direction to the maximum position allowed by the two tool posts. At this time, record the coordinate values P of the two tool posts in the machine tool coordinate system. 1max and P 2max , then the maximum distance allowed between the two tool holders is P max =ABS(P 1max )+ABS(P 2max )+P0; (1-6) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =ABS(P T2 -P T1 )+P0, and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max ; When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes; When P T ≥P max Trigger the alarm of the maximum allowable distance between the two tool holders and lock the corresponding movement directions of the two axes; (2) Data measurement of the same direction tool holder 1 in the positive direction of tool holder 2 (2-1) First, move the two tool holders of the machine tool to the respective zero points where they are to be set. Set the zero points. The coordinates displayed on the machine tool coordinate system are 0.

000. (2-2) Mark the lower reference point of tool holder 2; (2-3) Tool holder 2 moves away from the reference point mark in the negative direction, and then tool holder 1 moves negatively to the mark made by tool holder 2. At this time, the coordinate value P1 of tool holder 1 in the machine tool coordinate system is the zero point distance P0 = P1 between the two tool holders; (2-4) Stop tool holder 1 at the zero point, then move tool holder 2 to the minimum distance between the two tool holders. At this time, record the coordinate value P of tool holder 2 in the machine tool coordinate system. 2min , then the minimum distance P allowed between the two tool holders min =ABS(P 2min )+P0; (2-5) Open tool post 1 in the positive direction and tool post 2 in the negative direction to the maximum position allowed by the two tool posts. At this time, record the coordinate values P of the two tool posts in the machine tool coordinate system. 1max and P 2max , then the maximum distance allowed between the two tool holders is P max =ABS(P 1max )+ABS(P 2max )+P0; (2-6) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =ABS(P T1 -P T2 )+P0, and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max ; When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes; When P T ≥P max Trigger the alarm of the maximum allowable distance between the two tool holders and lock the corresponding movement directions of the two axes; (3) Data measurement with reverse zero point at the center (3-1) Move the two tool holders of the machine tool to the center point and set the zero point. The coordinate displayed by the machine tool coordinate system is 0.000, and the zero point distance between the two tool holders is P0 = 0. (3-2) Move tool post 1 to the zero position, and then move tool post 2 to the minimum position allowed by the machine. At this time, record the coordinate P of tool post 2 in the machine coordinate system. 2min , then the minimum distance P allowed between the two tool holders min =ABS(P 2min ); (3-3) Open the two tool holders to their respective extreme positions. At this time, record the coordinates P of tool holder 1 and tool holder 2 in the machine tool coordinate system. 1max and P 2max , then the maximum allowable distance P between the two tool holders is max =ABS(P 1max +P 2max ); (3-4) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =ABS(P T1 +P T2 ), and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max ; When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes; When P T ≥P max Trigger the alarm of the maximum allowable distance between the two tool holders and lock the corresponding movement directions of the two axes; (4) Data measurement with reverse zero point at both ends (4-1) First, move the two tool holders of the machine tool to the respective zero points where they are to be set. Set the zero points. The coordinates displayed on the machine tool coordinate system are 0.

000. (4-2) Mark the reference point at the center; (4-3) Open tool holder 1 and tool holder 2 to the reference point marks respectively, and record the coordinate value P1 of tool holder 1 and the coordinate value P2 of tool holder 2 in the machine tool coordinate system respectively. The zero point distance P0 of the two tool holders is P0 = ABS(P1 + P2); (4-3) Move tool holder 1 and tool holder 2 to the minimum position allowed by the machine, and record the coordinate value P of tool holder 1 in the machine coordinate system. 1min and the coordinate value P of tool holder 2 2min , then the minimum distance allowed between the two tool holders is P min =P0-ABS(P 1min +P 2min ); (4-4) Open the two tool holders to their respective limit positions. At this time, record the coordinates P of tool holder 1 and tool holder 2 in the machine tool coordinate system. 1max and P 2max , then the maximum allowable distance P between the two tool holders is max =P0+ABS(P 1max +P 2max ); (4-5) Use PLC to read the real-time coordinate values P of tool holder 1 and tool holder 2 respectively T1 and P T2 , PLC automatically calculates the real-time distance between the two tool holders as P T =P0+P T1 +P T2 , and then use PLC to compare the real-time spacing P T and minimum spacing P min and the maximum spacing P max When P T ≤P min Trigger the alarm of the minimum distance allowed between the two tool holders and lock the corresponding movement directions of the two axes; When P T ≥P max The maximum allowable distance between the two tool holders is triggered, and the corresponding movement directions of the two axes are locked.

2. The anti-collision protection method for a PLC-based double-turret machine tool according to claim 1, characterized in that: The movement mode of the servo motor of the tool holder axis is a linear axis.

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