Horizontal numerical control machine tool and Z-axis droop real-time compensation system and method thereof

Abstract

The invention relates to a horizontal numerical control machine tool and a Z-axis droop real-time compensation system and method.The Z-axis droop real-time compensation system can comprise a Z-axis droop amount measuring unit, a Z-axis droop amount measuring unit and a Z-axis droop amount measuring unit, and the Z-axis droop amount measuring unit is installed on the horizontal numerical control machine tool, is in communication connection with a CNC controller of the horizontal numerical control machine tool and is used for measuring the Z-axis droop amount in real time; and the compensation execution unit is integrated in the CNC controller and is used for injecting the Z-axis droop amount into a CNC position control ring in real time so as to realize dynamic compensation. The system is compact in structure, can be easily integrated on the existing horizontal numerical control machine tool, is low in improvement cost, can realize on-line, real-time and non-contact measurement of the Z-axis droop amount, and remarkably improves the machining precision of the horizontal numerical control machine tool under the long-stroke Z-axis working condition.

Description

Technical Field

[0001] This invention belongs to the field of horizontal CNC machine tools, specifically relating to a horizontal CNC machine tool and its Z-axis sag real-time compensation system and method. Background Technology

[0002] In horizontal CNC machine tools (such as horizontal machining centers), the Z-axis is usually a vertically moving spindle slide. When the Z-axis extends a long stroke, the spindle assembly's own weight causes elastic deformation of the Z-axis structure (i.e., "drooping"), resulting in the actual tool position deviating from the theoretically programmed position, which seriously affects machining accuracy, especially in the machining of high-precision parts (such as aerospace structural components and precision molds).

[0003] In existing technologies, the following methods are commonly used to address the Z-axis sag problem: Mechanical pre-deformation compensation: The Z-axis guide rail or column is pre-bent in the reverse direction during the machine tool design stage to offset part of the gravitational deformation. However, this method is only applicable to fixed working conditions and cannot adapt to different extension lengths and load changes. Lookup table compensation: This method involves offline measurement of sag at different Z-axis positions to establish a compensation lookup table, which is then used to retrieve the corresponding compensation value based on the Z-coordinate during machining. However, this method does not consider real-time factors such as temperature, wear, and dynamic load, resulting in limited compensation accuracy. Using a closed-loop feedback grating ruler can improve position control accuracy, but it cannot directly sense the minute displacements at the spindle end caused by structural flexibility.

[0004] Therefore, there is an urgent need for a technical solution that can measure Z-axis sag in real time, online, and with high precision, and achieve dynamic compensation. Summary of the Invention

[0005] The purpose of this invention is to provide a horizontal CNC machine tool and its Z-axis sag real-time compensation system and method to solve the above-mentioned problems. Therefore, the technical solution adopted by this invention is as follows: According to one aspect of the present invention, a real-time Z-axis sag compensation system for a horizontal CNC machine tool is provided, which may include: The Z-axis sag measurement unit is installed on a horizontal CNC machine tool and communicates with the CNC controller of the horizontal CNC machine tool to measure the Z-axis sag in real time. The compensation execution unit is integrated into the CNC controller and is used to inject the Z-axis sag into the CNC position control loop in real time to achieve dynamic compensation.

[0006] In one embodiment, the Z-axis sag measurement unit includes a laser emitting device, a laser receiving device, and a signal processing module. One of the laser emitting device and the laser receiving device is installed at a predetermined position near the Z-axis end of the horizontal CNC machine tool, and the other is installed on a fixed part of the machine tool bed. The laser emitting device emits a collimated laser beam along the Z-axis direction. The laser receiving device receives the spot signal from the laser emitting device. The signal processing module is electrically connected to the laser receiving device and processes the input signal from the laser receiving device into the Z-axis sag. The signal processing module is communicatively connected to the CNC controller and sends the Z-axis sag to the CNC controller.

[0007] In one embodiment, the laser receiving device is a CCD sensor.

[0008] In one embodiment, the CCD sensor is mounted at a predetermined position near the Z-axis of the horizontal CNC machine tool.

[0009] In one embodiment, the Z-axis sag measurement unit includes a strain gauge and a signal processing module. The strain gauge is fixedly installed at a predetermined position near the Z-axis end of the horizontal CNC machine tool and electrically connected to the signal processing module. The signal processing module is communicatively connected to the CNC controller and is used to process the input signal of the strain gauge into the Z-axis sag and send it to the CNC controller.

[0010] In one embodiment, the Z-axis sag measurement unit is connected to the CNC controller via EtherCAT, PROFINET, or a dedicated analog interface.

[0011] In one embodiment, the predetermined position is a distance of less than 20 mm from the Z-axis end face.

[0012] According to another aspect of the present invention, a method for real-time compensation of Z-axis sag in a horizontal CNC machine tool is also provided, which may include the following steps: Provides a real-time Z-axis sag compensation system for horizontal CNC machine tools as described above; The Z-axis sag measurement unit acquires the Z-axis sag in real time. The Z-axis sag is injected into the CNC position control loop in real time through the compensation execution unit to achieve dynamic compensation.

[0013] In one embodiment, the compensation execution unit injects the Z-axis droop amount into the CNC position control loop in real time to achieve dynamic compensation. Specifically, the CNC controller superimposes a negative Z-axis droop amount into the position command, causing the servo system to drive the Z-axis to move the Z-axis upward by the additional Z-axis droop amount, thereby offsetting the Z-axis droop effect.

[0014] According to another aspect of the present invention, a horizontal CNC machine tool is also provided, wherein the horizontal CNC machine tool includes the real-time Z-axis sag compensation system of the horizontal CNC machine tool as described above.

[0015] The beneficial effects of adopting the above technical solution in this invention are: 1. Enables online, real-time, non-contact measurement of Z-axis sag, avoiding the lag of traditional offline calibration; 2. The compensation accuracy can reach within ±1μm, significantly improving the machining accuracy of horizontal CNC machine tools under long-stroke Z-axis conditions; 3. The system has a compact structure, is easy to integrate into existing horizontal CNC machine tools, and has low modification costs; 4. It can adapt to different Z-axis extension lengths, spindle loads and ambient temperature changes, and has strong robustness. Attached Figure Description

[0016] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention, primarily used to illustrate the embodiments and to explain the operating principles of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0017] Figure 1 This is a schematic diagram of the Z-axis sag real-time compensation system for a horizontal CNC machine tool according to the first embodiment of the present invention; Figure 2 yes Figure 1 The diagram shows the compensation principle of the real-time compensation system for Z-axis sag on a horizontal CNC machine tool. Figure 3 This is a schematic diagram of the Z-axis sag real-time compensation system for a horizontal CNC machine tool according to a second embodiment of the present invention; Figure 4 yes Figure 1 The flowchart shows a real-time compensation method for Z-axis sag on a horizontal CNC machine tool. Detailed Implementation

[0018] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings to provide a clearer understanding of the purpose, features, and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative of the essential spirit of the technical solution of the present invention.

[0019] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0020] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0021] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0022] The singular forms “a” and “the” used in this specification and the appended claims include plural references unless otherwise expressly stated herein. It should be noted that the term “or” is generally used to mean “and / or” unless otherwise expressly stated herein.

[0023] In the following description, in order to clearly demonstrate the structure and operation of the present invention, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0024] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0026] First Embodiment like Figure 1 and 2 As shown, the first embodiment of the present invention provides a real-time Z-axis sag compensation system for a horizontal CNC machine tool, which may include a laser emitting device (also referred to as a laser) 1, a laser receiving device (e.g., a CCD sensor or a CMOS sensor, etc.) 2, a signal processing module (not shown), and a compensation execution unit. The laser emitting device 1, the laser receiving device 2, and the signal processing module constitute a Z-axis sag measurement unit for real-time measurement of the Z-axis sag. In the illustrated embodiment, the laser 1 is fixedly installed on the bed of the horizontal CNC machine tool 100 and can emit a collimated laser beam along the Z-axis direction. The laser receiving device 2 is installed at a predetermined position near the end of the Z-axis 101 of the horizontal CNC machine tool to receive the spot signal from the laser emitting device 1. When the Z-axis extends, due to gravity, the end of the Z-axis sags, causing the laser receiving device 2 to deviate from its original position; that is, the spot position of the laser emitted by the laser 1 on the laser receiving device 2 also shifts downwards. The signal processing module is electrically connected to the laser receiver 2 and processes the input signal from the laser receiver 2 into a Z-axis droop. The signal processing module is also communicatively connected to the CNC controller (e.g., via EtherCAT, PROFINET, a dedicated analog interface, or RS232 / 485) to send the Z-axis droop to the CNC controller. A compensation execution unit is integrated into the CNC controller and injects the Z-axis droop into the CNC position control loop in real time to achieve dynamic compensation.

[0027] Figure 2 The diagram illustrates the working principle of the real-time Z-axis sag compensation system for a horizontal CNC machine tool according to the present invention. When the Z-axis 100 extends, if sag occurs, the CCD sensor 2 shifts accordingly, causing a change in the position of the laser spot on the CCD sensor. The CCD sensor transmits the spot coordinates (x, y) to the signal processing module, which processes and converts them into the vertical displacement of the Z-axis end (i.e., the Z-axis sag) Δz. This Δz is sent to the CNC controller in real time via EtherCAT, PROFINET, or a dedicated analog interface. The CNC controller adds -Δz (the negative sign indicates reverse compensation) to the position command, causing the servo system to drive the Z-axis to move additionally upward by Δz, thereby offsetting the sag effect, i.e., compensating for the vertical displacement of the tool head.

[0028] Experiments show that when the Z-axis extends 800mm beyond 100mm, the Z-axis sag reaches 32μm without compensation, and the residual error is less than 1μm after adopting the present invention.

[0029] In this embodiment, the laser 1 is mounted on a fixed part of the bed of the horizontal CNC machine tool, meaning the position of the laser 1 will not change as the Z-axis extends. The CCD sensor is mounted at a predetermined position near the end of the Z-axis, for example, less than 20mm from the Z-axis end face; that is, the position of the CCD sensor is equivalent to the position at the end of the Z-axis. It should be understood that the mounting positions of the laser 1 and the CCD sensor can also be interchanged.

[0030] The laser emitted by laser 1 can be red or green, etc. Preferably, the laser is red and its wavelength is 635nm. Laser 1 and CCD sensor are commercially available, and their structures are well known, so they will not be described in detail here.

[0031] Second Embodiment like Figure 4 As shown, the difference between this embodiment and the first embodiment lies in the specific structure of the Z-axis sag measurement unit. In this embodiment, a strain gauge is used to measure the Z-axis sag. Specifically, the Z-axis sag measurement unit includes a strain gauge 3 and a signal processing module (not shown). The strain gauge 3 is fixedly installed at a predetermined position near the end of the Z-axis 101 of the horizontal CNC machine tool 100 (for example, the distance from the Z-axis end face is less than 20mm) and electrically connected to the signal processing module. The signal processing module is communicatively connected to the CNC controller of the horizontal CNC machine tool 100 and is used to process the input signal of the strain gauge into the Z-axis sag and send it to the CNC controller. A compensation execution unit is integrated in the CNC controller and is used to inject the Z-axis sag into the CNC position control loop in real time to achieve dynamic compensation. The structure and working principle of the strain gauge 3 are well known and will not be described in detail here.

[0032] The signal generated by strain gauge 3 is transmitted to the signal processing module, where it is processed and converted into the vertical displacement of the Z-axis end (i.e., Z-axis sag) Δz. This Δz is sent to the CNC controller in real time via EtherCAT, PROFINET, or a dedicated analog interface. The CNC controller adds -Δz (the negative sign indicates reverse compensation) to the position command, causing the servo system to drive the Z-axis to move additionally upward by Δz, thereby offsetting the sag effect, i.e., compensating for the vertical displacement of the tool tip.

[0033] like Figure 4 As shown, according to another aspect of the present invention, a method for real-time compensation of Z-axis sag in a horizontal CNC machine tool is also provided, which may include the following steps: S1. Provide the Z-axis sag real-time compensation system for the horizontal CNC machine tool as described above; S2. The Z-axis sag measurement unit is used to obtain the Z-axis sag in real time. S3. The Z-axis droop is injected into the CNC position control loop in real time through the compensation execution unit to achieve dynamic compensation. Specifically, the CNC controller superimposes a negative Z-axis droop in the position command, causing the servo system to drive the Z-axis to move upward by the Z-axis droop, thereby counteracting the Z-axis droop effect.

[0034] In addition, the present invention also provides a horizontal CNC machine tool, wherein the horizontal CNC machine tool includes the real-time Z-axis sag compensation system of the horizontal CNC machine tool as described above.

[0035] The present invention has the following advantages: 1. Enables online, real-time, non-contact measurement of Z-axis sag, avoiding the lag of traditional offline calibration; 2. The compensation accuracy can reach within ±1μm, significantly improving the machining accuracy of horizontal CNC machine tools under long-stroke Z-axis conditions; 3. The system has a compact structure, is easy to integrate into existing horizontal CNC machine tools, and has low modification costs; 4. It can adapt to different Z-axis extension lengths, spindle loads and ambient temperature changes, and has strong robustness.

[0036] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings, those skilled in the art can make various alterations or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A real-time Z-axis sag compensation system for a horizontal CNC machine tool, characterized in that, include: The Z-axis sag measurement unit is installed on a horizontal CNC machine tool and communicates with the CNC controller of the horizontal CNC machine tool to measure the Z-axis sag in real time. The compensation execution unit is integrated into the CNC controller and is used to inject the Z-axis sag into the CNC position control loop in real time to achieve dynamic compensation.

2. The real-time Z-axis sag compensation system for horizontal CNC machine tools as described in claim 1, characterized in that, The Z-axis sag measurement unit includes a laser emitting device, a laser receiving device, and a signal processing module. One of the laser emitting device and the laser receiving device is installed at a predetermined position near the Z-axis end of the horizontal CNC machine tool, and the other is installed on a fixed part of the machine tool bed. The laser emitting device emits a collimated laser beam along the Z-axis direction. The laser receiving device receives the spot signal from the laser emitting device. The signal processing module is electrically connected to the laser receiving device and processes the input signal from the laser receiving device into the Z-axis sag measurement. The signal processing module is communicatively connected to the CNC controller and sends the Z-axis sag measurement to the CNC controller.

3. The real-time Z-axis sag compensation system for horizontal CNC machine tools as described in claim 2, characterized in that, The laser receiving device is a CCD sensor.

4. The real-time Z-axis sag compensation system for horizontal CNC machine tools as described in claim 3, characterized in that, The CCD sensor is installed at a predetermined position near the Z-axis of the horizontal CNC machine tool.

5. The real-time Z-axis sag compensation system for horizontal CNC machine tools as described in claim 1, characterized in that, The Z-axis sag measurement unit includes a strain gauge and a signal processing module. The strain gauge is fixedly installed at a predetermined position near the Z-axis end of the horizontal CNC machine tool and electrically connected to the signal processing module. The signal processing module is communicatively connected to the CNC controller and is used to process the input signal of the strain gauge into the Z-axis sag and send it to the CNC controller.

6. The real-time Z-axis sag compensation system for horizontal CNC machine tools as described in claim 1, characterized in that, The Z-axis sag measurement unit communicates with the CNC controller via EtherCAT, PROFINET, or a dedicated analog interface.

7. The real-time Z-axis sag compensation system for horizontal CNC machine tools as described in claim 4 or 5, characterized in that, The predetermined position is less than 20mm away from the Z-axis end face.

8. A method for real-time compensation of Z-axis sag on a horizontal CNC machine tool, characterized in that, Includes the following steps: Provide a real-time Z-axis sag compensation system for a horizontal CNC machine tool as described in any one of claims 1 to 7; The Z-axis sag is measured in real time by the Z-axis sag measurement unit. The Z-axis sag is injected into the CNC position control loop in real time through the compensation execution unit to achieve dynamic compensation.

9. The real-time compensation method for Z-axis sag of a horizontal CNC machine tool as described in claim 8, characterized in that, The compensation execution unit injects the Z-axis sag into the CNC position control loop in real time to achieve dynamic compensation. Specifically, the CNC controller superimposes a negative Z-axis sag in the position command, causing the servo system of the horizontal CNC machine tool to drive the Z-axis to move the Z-axis upward by an additional Z-axis sag, thereby offsetting the Z-axis sag effect.

10. A horizontal CNC machine tool, characterized in that, The horizontal CNC machine tool includes a real-time Z-axis sag compensation system as described in any one of claims 1 to 7.

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