A main shaft thermal deviation measurement method and system for a vertical machining center

Abstract

The application provides a main shaft thermal deviation measurement method and system for a vertical machining center, and belongs to the technical field of machine tool detection. The material, size and quantity of a test workpiece are selected. The selected test workpiece is clamped at the center of a workbench, and the environmental temperature of a test process is adjusted to a preset value. The following processes are performed under the condition that the cooling liquid is closed and under the condition that the cooling liquid is opened: the four sides of the test workpiece are machined at a preset rotating speed, and a first initial step surface is formed when a preset cutting depth and width are reached; a second initial step surface is milled; the first and second center point position coordinate values and the difference therebetween are measured as the tool center point thermal deviation. The main shaft thermal deviation value after spraying the cooling liquid can be measured, which is closer to the main shaft thermal deformation amount during actual machining of the machine tool, and more reliable data for error compensation of the machine tool is provided.

Description

Technical Field

[0001] This invention belongs to the field of machine tool testing technology, specifically relating to a method and system for measuring the thermal offset of a spindle in a vertical machining center. Background Technology

[0002] A vertical machining center is a CNC machine tool used for multi-stage machining of workpieces. The machining process is primarily achieved through the relative motion between the workpiece and the CNC machine tool, or by simultaneously using the workpiece and various moving parts of the CNC machine tool.

[0003] To ensure the accuracy of vertical machining centers during operation, offset is typically addressed. For example, CN202021739026.5 discloses a vertical machining center structure to prevent workpiece offset. This document includes a tooling fixture and a machining center base. The vertical machining center is rotatably mounted on the top surface of the machining center base, and a static permanent magnet clamp is fixedly mounted on the top surface of the tooling fixture. A sliding groove is formed on the top surface of the tooling fixture, and a moving permanent magnet clamp is slidably mounted inside the groove. An offset detection mechanism is embedded in the top surface of the tooling fixture. The moving permanent magnet clamp includes a clamp housing and a drive motor. A permanent magnet adsorption assembly is fixedly mounted inside the clamp housing, and the output end of the drive motor is fixedly connected to a linkage fork. This document uses a symmetrical permanent magnet adsorption fixture structure to clamp the two ends of the workpiece by using relatively arranged permanent magnet clamps, and uses the principle of permanent magnet adsorption to generate magnetic attraction between the two sides of the workpiece for adsorption and fixation.

[0004] However, during the operation of a vertical machining center, the high-speed rotation of the spindle motor continuously generates a large amount of heat, causing thermal deformation of various components inside the spindle. This leads to a relative displacement of the tool center point relative to the worktable, affecting the accuracy of the machined workpiece. How to determine the parameters of the relative displacement of the tool center point relative to the worktable caused by thermal deformation and effectively compensate for it, thereby reducing the impact of thermal deformation on machining accuracy, is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] This invention provides a method for measuring the thermal offset of a spindle in a vertical machining center, which can provide reliable and comprehensive data support for machine tool thermal error compensation.

[0006] The methods include:

[0007] Select the material, size, and quantity of the test workpieces;

[0008] The selected test workpiece is clamped in the center of the worktable, and the ambient temperature during the test is adjusted to the preset value.

[0009] The following procedures are performed with the coolant off and with the coolant on, respectively:

[0010] The four sides of the test workpiece are machined at a preset rotation speed to reach a preset cutting depth and width, forming the first initial step surface;

[0011] The four sides of the test workpiece are machined again at a preset rotation speed to reach a preset cutting depth and width, forming a second initial step surface;

[0012] Measure the coordinates of the first center point corresponding to the first initial step surface; measure the coordinates of the second center point corresponding to the second initial step surface;

[0013] Calculate the difference between the coordinates of the first center point and the coordinates of the second center point, and use it as the thermal offset of the tool center point.

[0014] It should be further noted that the materials selected for the test workpiece in the method include: aluminum, steel, and cast iron; the shape of the test workpiece is a cube.

[0015] It should be further noted that the ambient temperature in the method is set to 20℃ to 23℃.

[0016] It should be further noted that in the method, the four sides of the test workpiece are machined at a speed of 3000-3500 r / min to form the first step surface; the cutting depth is 20mm-25mm and the cutting width is 0.2mm-0.5mm.

[0017] It should be further noted that the tool is raised by 10 mm to 15 mm; the initial table surface is machined at a speed of 3000 to 3500 r / min to form the second step surface; the cutting depth is 10 mm to 15 mm and the cutting width is 0.2 mm to 0.5 mm.

[0018] It should be further noted that in the method, the time for the vertical machining center to start machining the four sides of the test workpiece is denoted as the start time t0; then, five data acquisition points are defined at 1-hour intervals, and the machining times t1, t2, t3, and t4 based on the four sides of the test workpiece are recorded respectively. 4。

[0019] It should be further noted that the method also includes: establishing a two-dimensional plane coordinate system based on the worktable of the vertical machining center;

[0020] In a two-dimensional plane coordinate system, obtain the coordinates of the four endpoints of the first initial step surface, and calculate the coordinate value of the first center point.

[0021] In a two-dimensional plane coordinate system, obtain the coordinates of the four endpoints of the second initial step surface, and calculate the coordinates of the second center point.

[0022] Calculate the difference between the coordinates of the first center point and the coordinates of the second center point, and use it as the thermal offset of the tool center point.

[0023] It should be further explained that the method also includes: within the processing time, drawing line graphs of milling thermal offset obtained at 1-hour intervals for test workpieces of different materials, and combining the tool radius and depth of cut data to obtain the spindle thermal offset under the two states of coolant on and off, which is used as the machine tool spindle thermal error compensation amount.

[0024] The present invention also provides a spindle thermal offset measurement system for a vertical machining center, the system comprising: a test terminal and a vertical machining center;

[0025] The testing terminal acquires the material, size, and quantity of the test workpiece selected by the user;

[0026] The selected test workpiece is clamped in the center of the worktable, and the ambient temperature during the test process is adjusted to the preset value and input into the test terminal.

[0027] The test terminal controlled the vertical machining center to perform the following procedures with the coolant off and with the coolant on:

[0028] The four sides of the test workpiece are machined at a preset rotation speed to reach a preset cutting depth and width, forming the first initial step surface;

[0029] The four sides of the test workpiece are machined again at a preset rotation speed to reach a preset cutting depth and width, forming a second initial step surface;

[0030] Measure the coordinates of the first center point corresponding to the first initial step surface; measure the coordinates of the second center point corresponding to the second initial step surface;

[0031] Calculate the difference between the coordinates of the first center point and the coordinates of the second center point, and use it as the thermal offset of the tool center point.

[0032] It should be further explained that the test terminal establishes a two-dimensional plane coordinate system based on the worktable of the vertical machining center; in the two-dimensional plane coordinate system, the coordinates of the four endpoints of the first initial step surface are obtained, and the coordinate value of the first center point is calculated; in the two-dimensional plane coordinate system, the coordinates of the four endpoints of the second initial step surface are obtained, and the coordinate value of the second center point is calculated; the difference between the coordinate values ​​of the first center point and the coordinate values ​​of the second center point is calculated as the thermal offset of the tool center point;

[0033] During the processing time, the test terminal plots line graphs of milling thermal offsets obtained at 1-hour intervals for test workpieces of different materials. Combined with tool radius and depth of cut data, the spindle thermal offsets are obtained under the two states of coolant on and off, which are used as the machine tool spindle thermal error compensation amount.

[0034] As can be seen from the above technical solutions, the present invention has the following advantages:

[0035] The method and system for measuring spindle thermal offset of vertical machining centers provided by this invention obtains the workpiece size deviation value by measuring the workpiece step surface size of two milling tests, and then measures the spindle thermal offset of the machining center. Compared with traditional measurement methods, this invention can measure the spindle thermal offset value after spraying coolant, which is closer to the spindle thermal deformation during actual machining, providing more reliable data for machine tool error compensation.

[0036] This invention can also obtain the spindle thermal offset curves of three commonly processed materials in a vertical machining center under two different cutting tests with and without coolant, providing more comprehensive data for machine tool error compensation, ensuring the machining accuracy of the vertical machining center, and meeting the cutting process requirements of the vertical machining center. Attached Figure Description

[0037] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying 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.

[0038] Figure 1 A schematic diagram of a spindle thermal offset measurement system for a vertical machining center;

[0039] Figure 2 A schematic diagram showing the workpiece being clamped at the center of the worktable;

[0040] Figure 3 This is a schematic diagram of coordinate points in an embodiment of the present invention. Detailed Implementation

[0041] In the spindle thermal offset measurement method and system for vertical machining centers provided by this invention, various embodiments of the present disclosure will be described more fully. The present disclosure may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of the present disclosure to the specific embodiments disclosed herein, but rather the present disclosure should be understood to cover all adjustments, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of the present disclosure.

[0042] In the following, the terms “comprising” or “may include”, which may be used in various embodiments of this disclosure, indicate the presence of the disclosed functions, operations, or elements, and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in various embodiments of this disclosure, the terms “comprising,” “having,” and their cognates are intended only to indicate a particular feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or the possibility of adding one or more combinations of the foregoing.

[0043] In various embodiments of this disclosure, the expression "or" or "at least one of A and / or B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A and / or B" may include A, may include B, or may include both A and B.

[0044] The terms used in the various embodiments of this disclosure (such as "first," "second," etc.) may modify various components in the various embodiments, but do not limit the corresponding components. For example, the above terms do not limit the order and / or importance of the components. The above terms are only used for the purpose of distinguishing one component from others. For example, a first user device and a second user device refer to different user devices, although both are user devices. For example, a first component may be referred to as a second component without departing from the scope of the various embodiments of this disclosure, and similarly, a second component may also be referred to as a first component.

[0045] It should be noted that: Figure 1 As shown, the spindle thermal offset measurement system for vertical machining centers provided by this invention includes a test terminal and a vertical machining center.

[0046] The vertical machining center involved in this invention is a CNC machine tool equipped with a tool magazine and capable of automatic tool changing, performing multi-process machining on workpieces. The vertical machining center includes: a bed, a worktable, a gantry column, a spindle box, a spindle motor, a bed spindle, and bed bearings, etc. The bed spindle is the power output element for cutting operations, driven by a drive motor, and can be connected to components such as lead screws, guide rails, slides, and bearings.

[0047] Vertical machining centers can have three linear motion axes and can move in conjunction with each other in two of the axes. The machining process can be achieved by relying on the relative motion between the workpiece and the CNC machine tool, or by simultaneously using the workpiece and various moving parts of the CNC machine tool.

[0048] Vertical machining centers also include lubrication systems, cooling systems, hydraulic systems, pneumatic systems, and detection systems, which can ensure the normal operation and machining quality of the vertical machining center.

[0049] In the embodiments provided by the present invention, the measurement results of the workpiece spatial position in two milling tests of the vertical machining center with the coolant on and off are affected by a variety of factors, including but not limited to: the temperature and flow rate of the coolant: the temperature and flow rate of the coolant will affect the thermal deformation of the tool and the workpiece, and thus affect the spatial position of the workpiece.

[0050] In the embodiments provided by this invention, milling parameters are also considered during measurement. These parameters mainly include milling speed, feed rate, and depth of cut, which affect the material removal rate and thermal deformation of the test workpiece. Tool wear is not considered in this embodiment.

[0051] In the embodiments provided by this invention, the selected workpiece material can be steel, aluminum, or cast iron. This is because different materials have different coefficients of thermal expansion and moduli of elasticity, which will affect the deformation of the workpiece during cooling and non-cooling processes. Ambient temperature and humidity are also considered during the testing process to improve the accuracy of the test. Therefore, when comparing the results of two milling tests with the coolant on and off, this invention can comprehensively consider the above factors, ensuring the effectiveness of the test.

[0052] The test terminal in this embodiment includes a wireless communication module, an input / output module, a sensing module, a memory, an interface module, a controller, and a power supply module, etc. However, it should be understood that it is not required to implement all the components shown. More or fewer components may be implemented alternatively.

[0053] The input / output module can receive input digital or character information, and generate key signal inputs related to user settings and function control for measuring the spindle thermal offset of the vertical machining center in this embodiment, such as touch screens, mice, trackpads, touch panels, indicator sticks, etc. It may also include LCD monitors, display devices, auxiliary lighting devices, etc.

[0054] This embodiment uses, for example, a communication network to connect the components of the system to each other. Examples of communication networks include: Local Area Network (LAN), Wide Area Network (WAN), and the Internet.

[0055] In this embodiment, the test terminal can be used in conjunction with a vertical machining center. The test terminal has a control program that can be provided to the vertical machining center based on a PLC control program to realize automated machining.

[0056] 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, and 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.

[0057] The spindle thermal offset measurement method for vertical machining centers provided in this embodiment includes:

[0058] S101: Select the material, size, and quantity of the test workpiece.

[0059] In this embodiment, the materials selected for the test workpieces are aluminum, steel, and cast iron. The test workpieces can be made of 160mm×160mm×160mm plates, and the number of pieces is 30, consisting of 10 aluminum test workpieces, 10 steel test workpieces, and 10 cast iron test workpieces.

[0060] S102: Clamp the selected test workpiece in the center of the worktable and adjust the ambient temperature of the test process to the preset value.

[0061] In one exemplary embodiment, one test workpiece of each material is clamped at the center of the worktable, and the workpiece is kept clamped and positioned consistently throughout the milling process for cutting operations.

[0062] Optionally, the ambient temperature during the cutting process is a constant 20°C to 23°C.

[0063] S103: Perform the following procedures when the coolant is off and when the coolant is on:

[0064] With the coolant off, the four sides of the test workpiece are machined at a preset speed to reach a preset cutting depth and width, and the first initial step surface is milled out with the coolant off.

[0065] In one exemplary embodiment, with the coolant off, two milling operations are performed. In the first milling test, after the vertical machining center is turned on, the workpiece is cut immediately at time t0 to mill the first step surface. The coolant is off during this milling operation. After the initial milling of the first milling test, milling continues to mill the second step surface. The coolant is still off during this milling operation.

[0066] In one exemplary embodiment, with the coolant on, the four sides of the test workpiece are machined at a preset rotation speed to reach a preset cutting depth and width, forming a first initial step surface; the four sides of the test workpiece are then machined again at the preset rotation speed to reach the preset cutting depth and width, forming a second initial step surface. That is, after the vertical machining center is started, the workpiece is initially cut with the coolant on to mill the initial step surface. After the initial milling in the second milling test, milling continues to form the second step surface, with the coolant on throughout this milling process.

[0067] Here, the first actual value of the first initial step surface based on the X or Y direction can be measured when the coolant is on and off, respectively; the second actual value of the second initial step surface based on the X or Y direction can be measured; and the thermal offset of the machine tool in the X or Y direction can be analyzed when the coolant is on and off.

[0068] Furthermore, the coordinates of the first center point corresponding to the first initial step surface are measured; the coordinates of the second center point corresponding to the second initial step surface are measured; and the difference between the coordinates of the first center point and the coordinates of the second center point is calculated as the thermal offset of the tool center point.

[0069] In one exemplary embodiment, such as Figure 2 As shown, the four sides of the test workpiece are machined at a speed of 3000-3500 r / min to form the first step surface; the cutting depth is 20mm-25mm and the cutting width is 0.2mm-0.5mm.

[0070] Then control the tool to rise 10 mm - 15 mm; continue machining the initial table surface at a speed of 3000~3500 r / min to form the second step surface; the cutting depth is 10 mm - 15 mm, and the cutting width is 0.2 mm - 0.5 mm.

[0071] Optionally, a vertical machining center is used to machine the four side planes of the workpiece at a speed of 3000-3500 r / min, with a cutting depth of 20 mm and a cutting width of 0.2 mm, to mill the initial step surface. Then, the initial table surface is machined at a speed of 3000-3500 r / min, while the tool rises by 10 mm, changing the cutting depth to 10 mm and the cutting width to 0.2 mm.

[0072] It should be noted that the measurement of the first initial step surface with the coolant off is based on the first actual value of the coolant off condition in the X and / or Y directions; the measurement of the second initial step surface with the coolant on is based on the second actual value of the coolant on condition in the X and / or Y directions. Both the first and second initial step surfaces can be understood as referring to the first step surface. In other words, the initial step surface obtained under both coolant off and coolant on conditions is the first step surface; the comparison here is based on the actual values ​​of the first step surface.

[0073] Of course, in this embodiment, the second step surface can also be used as both the first and second initial step surfaces, and the actual values ​​of the second step surface can be compared. Whether the first or second step surface is used as the initial step surface is not limited here.

[0074] As a specific embodiment of the present invention, the present invention relates to 10 aluminum test workpieces, 10 steel test workpieces and 10 cast iron test workpieces. The above process simultaneously measures 1 aluminum test workpiece, 1 steel test workpiece and 1 cast iron test workpiece, and then measures a second aluminum test workpiece, a steel test workpiece and a cast iron test workpiece, until all 10 workpieces are measured.

[0075] In an exemplary embodiment, the vertical machining center is turned on for the time it takes to process the four sides of the test workpiece, denoted as the start time t0; then, at 1-hour intervals, 5 data acquisition points are defined, and the processing times t1, t2, t3, and t4 based on the four sides of the test workpiece are recorded respectively. 4。

[0076] It should be noted that the intervals are 1 hour, and the times are denoted as t1, t2, t3, and t4. 4， The initial step surface and the second step surface are milled, and the coolant is turned off during the milling process.

[0077] Each time interval is 1 hour, and the time is denoted as t1, t2, t3, t4. 4， The initial step surface and the second step surface are milled, and the coolant is turned on during the milling process.

[0078] More specifically, such as Figure 3 As shown, after two milling tests with the coolant on and off in the vertical machining center, the workpiece was left to cool down. Then, a coordinate measuring machine was used to inspect the workpiece to obtain the spatial position of the corresponding step surface. The initial X and Y coordinates of the four endpoints of the step surface were (x1, y1), (x2, y2), (x3, y3), and (x4, y4). The coordinates of the center point O were calculated as ((x1+x2+x3+x4) / 4, (y1+y2+y3+y4) / 4).

[0079] The coordinates of the four endpoints of the second step surface in the X and Y directions are (x1) ’ y1 ’ ), (x2) ’ y2 ’ ), (x3 ’ y3 ’ ), (x4 ’ y4 ’ The coordinates of the center point O are calculated. ’ ((x1 ’ +x2 ’ +x3 ’ +x4 ’ ) / 4, (y1 ’ +y2 ’ +y3 ’ +y4 ’ ) / 4).

[0080] O、O ’ The algebraic difference between the two points can be approximated as the thermal offset of the tool center point.

[0081] This embodiment generates a line graph of the milling thermal offset of three materials at 1-hour intervals over 5 hours. Combined with tool radius and depth of cut data, the spindle thermal offset under coolant on and off states is obtained, thereby achieving effective compensation for machine tool spindle thermal error.

[0082] The present invention provides a method for measuring the thermal offset of a vertical machining center spindle. By measuring the workpiece step surface dimensions in two milling tests, the workpiece dimensional deviation value is obtained, and then the thermal offset of the machining center spindle is measured. Compared with traditional measurement methods, the present invention can measure the spindle thermal offset value after spraying coolant, which is closer to the spindle thermal deformation during actual machining, providing more reliable data for machine tool error compensation.

[0083] The following are embodiments of the spindle thermal offset measurement system for vertical machining centers provided in this disclosure. This system and the spindle thermal offset measurement methods for vertical machining centers described above belong to the same inventive concept. For details not described in detail in the embodiments of the spindle thermal offset measurement system for vertical machining centers, please refer to the embodiments of the spindle thermal offset measurement methods for vertical machining centers described above.

[0084] In this embodiment, the testing terminal acquires the material, size, and quantity of the test workpiece selected by the user; the selected test workpiece is clamped in the center of the worktable, and the ambient temperature during the testing process is adjusted to a preset value and input to the testing terminal; the testing terminal controls the vertical machining center to process the four sides of the test workpiece at a preset speed with the coolant off, reaching a preset cutting depth and width, and milling out the initial step surface with the coolant off; and controls the vertical machining center to process the four sides of the test workpiece at a preset speed with the coolant on, reaching a preset cutting depth and width, and milling out the initial step surface with the coolant on; the testing terminal measures the initial step surface with the coolant off based on the actual values ​​in the X and / or Y directions with the coolant off; it also measures the initial step surface with the coolant on based on the actual values ​​in the X and / or Y directions with the coolant on; and analyzes the thermal offset of the machine tool in the X and / or Y directions under the two states of coolant on and off, using this as thermal error compensation data for the machining center.

[0085] As an implementation of the system of the present invention, aluminum, a material commonly processed by machining centers, is first selected as the cutting part, which is clamped in the center of the worktable and kept stationary, while ensuring that the external temperature remains constant during the measurement process.

[0086] In an embodiment of the present invention, during the first milling test, the machining center performs cutting after being turned on to obtain the initial step surface of the workpiece. Subsequently, the tool is removed from the workpiece and idles. During this process, the workpiece position remains unchanged. After the machining center reaches thermal equilibrium, cutting continues. During the continued cutting, cutting is performed on the step surface obtained from the initial cutting. Compared to the initial cutting, the tool needs to be raised by 10mm. The other machining parameters remain unchanged. The coolant is not turned on during the entire first milling test.

[0087] In the second milling test, a brand new workpiece of the same specifications as in the first milling test was used and placed in the same position. After the machining center was turned on, the coolant was turned on and cutting was performed to obtain the initial step surface of the workpiece. Then the tool was removed from the workpiece and idled. During this process, the workpiece position remained unchanged. After the machining center reached thermal equilibrium, cutting continued. Cutting was performed on the initial step surface. Compared with the initial cutting, the tool needed to be raised by 10mm. The other machining parameters remained unchanged. The coolant was turned on throughout the second milling test.

[0088] In an embodiment of the system of the present invention, after machining is completed, the workpieces processed in the two trials are left to cool down, and then the dimensions of the workpieces are measured. First, the actual values ​​of the X and Y deviations of the two step surfaces obtained in the first milling are measured, and the X and / or Y deviation values ​​of the two step surfaces in the first milling trial are calculated based on these values. Then, the actual values ​​of the X and / or Y deviations of the two surfaces obtained in the second milling are measured, and the X and / or Y deviation values ​​of the two step surfaces in the second milling trial are calculated based on these values. Finally, the thermal offset of the machine tool in the X and / or Y directions under the two states of coolant on and off are comprehensively analyzed, so as to provide data reference for thermal error compensation of the machining center.

[0089] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0090] In embodiments of the methods and systems of the present invention, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of devices, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than that shown in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved.

[0091] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for measuring spindle thermal offset in a vertical machining center, characterized in that, The methods include: Select the material, size, and quantity of the test workpieces; The selected test workpiece is clamped in the center of the worktable, and the ambient temperature during the test is adjusted to the preset value. The following procedures are performed with the coolant off and with the coolant on, respectively: The four sides of the test workpiece are machined at a preset rotation speed to reach a preset cutting depth and width, forming the first initial step surface; The four sides of the test workpiece are machined again at a preset rotation speed to reach a preset cutting depth and width, forming a second initial step surface; Measure the coordinates of the first center point corresponding to the first initial step surface; measure the coordinates of the second center point corresponding to the second initial step surface; Calculate the difference between the coordinates of the first center point and the coordinates of the second center point, and use it as the thermal offset of the tool center point.

2. The method for measuring spindle thermal offset in a vertical machining center according to claim 1, characterized in that, In this method, the materials selected for the test workpiece include: aluminum, steel, and cast iron; The test workpiece is a cube.

3. The method for measuring spindle thermal offset in a vertical machining center according to claim 1, characterized in that, In this method, the ambient temperature is set to 20℃ to 23℃.

4. The method for measuring spindle thermal offset in a vertical machining center according to claim 1, characterized in that, In this method, the four sides of the test workpiece are machined at a rotation speed of 3000-3500 r / min to form the first initial step surface; the cutting depth is 20mm-25mm and the cutting width is 0.2mm-0.5mm.

5. The method for measuring spindle thermal offset in a vertical machining center according to claim 4, characterized in that, Control the tool to rise 10 mm - 15 mm; continue machining the four sides of the test workpiece at a speed of 3000~3500 r / min to form the second initial step surface; the cutting depth is 10 mm - 15 mm, and the cutting width is 0.2 mm - 0.5 mm.

6. The method for measuring spindle thermal offset in a vertical machining center according to claim 5, characterized in that, The method also includes: establishing a two-dimensional planar coordinate system based on the worktable of a vertical machining center; In a two-dimensional plane coordinate system, obtain the coordinates of the four endpoints of the first initial step surface, and calculate the coordinate value of the first center point. In a two-dimensional plane coordinate system, obtain the coordinates of the four endpoints of the second initial step surface, and calculate the coordinates of the second center point. Calculate the difference between the coordinates of the first center point and the coordinates of the second center point, and use it as the thermal offset of the tool center point.

7. The method for measuring spindle thermal offset in a vertical machining center according to claim 6, characterized in that, The method also includes: within the processing time, drawing line graphs of milling thermal offsets obtained at 1-hour intervals for test workpieces of different materials, and combining the tool radius and depth of cut data to obtain the spindle thermal offsets under the two states of coolant on and off, which are used as the machine tool spindle thermal error compensation amount.

8. A spindle thermal offset measurement system for a vertical machining center, characterized in that, The system is used to implement the spindle thermal offset measurement method for vertical machining centers as described in any one of claims 1 to 7; the system includes: a test terminal and a vertical machining center; The testing terminal acquires the material, size, and quantity of the test workpiece selected by the user; The selected test workpiece is clamped in the center of the worktable, and the ambient temperature during the test process is adjusted to the preset value and then input into the test terminal. The test terminal controlled the vertical machining center to perform the following processes with the coolant off and with the coolant on: The four sides of the test workpiece are machined at a preset rotation speed to reach a preset cutting depth and width, forming the first initial step surface; The four sides of the test workpiece are machined again at a preset rotation speed to reach a preset cutting depth and width, forming a second initial step surface; Measure the coordinates of the first center point corresponding to the first initial step surface; measure the coordinates of the second center point corresponding to the second initial step surface; Calculate the difference between the coordinates of the first center point and the coordinates of the second center point, and use it as the thermal offset of the tool center point.

9. The spindle thermal offset measurement system for vertical machining centers according to claim 8, characterized in that, The test terminal establishes a two-dimensional plane coordinate system based on the worktable of the vertical machining center; in the two-dimensional plane coordinate system, the coordinates of the four endpoints of the first initial step surface are obtained, and the coordinate value of the first center point is calculated; in the two-dimensional plane coordinate system, the coordinates of the four endpoints of the second initial step surface are obtained, and the coordinate value of the second center point is calculated. Calculate the difference between the coordinates of the first center point and the coordinates of the second center point, and use it as the thermal offset of the tool center point; During the processing time, the test terminal plots line graphs of milling thermal offsets obtained at 1-hour intervals for test workpieces of different materials. Combined with tool radius and depth of cut data, the spindle thermal offsets are obtained under the two states of coolant on and off, which are used as the machine tool spindle thermal error compensation amount.

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