A four-axis unit CNC machining center

Abstract

The present invention discloses a four-axis unit CNC machining center, which belongs to the field of CNC machining and includes a CNC center main body, wherein the bottom platform of the CNC center main body is provided with a Y-axis movable guide rail, and an X-axis movable guide rail is fixedly provided on the Y-axis movable guide rail; one side of the CNC center main body is fixedly connected to the Z-axis movable guide rail, and the CNC center main body is movably connected to a tool drive module through the Z-axis movable guide rail, and a fourth axis assembly is fixedly connected to the X-axis movable guide rail, and the lower end of the tool spindle is detachably connected to a leveling assembly for leveling the fourth axis assembly. The present application provides a leveling assembly and a hydraulic support assembly, and first, when detecting the flatness of the reference surface of a large bridge plate, it is no longer necessary to manually use a dial indicator to detect the flatness in multiple areas, thereby realizing automated detection, simplifying the operating steps, and avoiding the subjective degree error caused by manual detection, thereby improving the leveling efficiency.

Description

Technical Field

[0001] The present invention relates to the field of numerical control machining, and more particularly to a four-axis unit numerical control machining center. Background Art

[0002] Four-axis CNC machining centers build upon traditional three-axis machining (X, Y, Z) with an additional rotary axis. This can be the A-axis (rotating around the X-axis), the B-axis (rotating around the Y-axis), or the C-axis (rotating around the Z-axis). This rotary axis enables the machining platform to rotate, allowing the machine tool to perform more automated machining operations during the machining process. Four-axis machining centers are an advanced version of three-axis machining centers, capable of multi-surface machining, reducing clamping times and improving machining efficiency.

[0003] During the machining cycle of a four-axis CNC machining center, to ensure machining accuracy and equipment stability, the fourth-axis bridge plate needs to be leveled more frequently based on factors such as machining frequency and load intensity, ambient temperature and humidity fluctuations, material properties, and stress release. For example, during high-frequency machining, the bridge plate needs to be leveled every 20-30 pieces. When the temperature changes by more than 5°C or the humidity fluctuates by more than 30%, the bridge plate is prone to thermal expansion and contraction, requiring an additional leveling operation before the shift change.

[0004] When leveling the fourth-axis bridge deck, the following three steps are usually required: 1. Check the flatness of the bridge deck reference surface; 2. Check the Z-axis rotation center; 3. Check the Y-axis rotation center; In the actual leveling process, for large bridge decks, when checking the flatness of the bridge deck reference surface, it is usually necessary to use a dial indicator to check the flatness in multiple areas (500mm), and then make adjustments step by step. The operation steps are cumbersome (such as the dial indicator needs to be moved repeatedly and the data needs to be recorded), and the leveling efficiency is low. In addition, for large bridge decks, due to the large span of the bridge and the influence of its own weight, local bending deformation is prone to occur in the mid-span position, which leads to errors in flatness after calibration, affecting the processing accuracy. Summary of the Invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a four-axis unit CNC machining center.

[0006] To solve the above problems, the present invention adopts the following technical solutions.

[0007] A four-axis unit CNC machining center includes a CNC center body, a bottom platform of the CNC center body is provided with a Y-axis movable guide rail, and an X-axis movable guide rail is fixedly provided on the Y-axis movable guide rail; one side of the CNC center body is fixedly connected to the Z-axis movable guide rail, and the CNC center body is movably connected to a tool drive module through the Z-axis movable guide rail, and the lower end of the tool drive module is fixedly connected to a tool spindle;

[0008] The fourth axis assembly is fixedly connected to the X-axis movable guide rail, and the lower end of the tool spindle is detachably connected to a horizontal leveling assembly for leveling the fourth axis assembly.

[0009] Furthermore, the horizontal leveling assembly includes a main connecting rod and a processing unit, and the main connecting rod is provided with a connecting portion and is detachably connected to the tool spindle through the connecting portion, and the connecting portion and the tool spindle can be optionally connected by a threaded connection or a hydraulic clamping connection; the bottom of the main connecting rod is fixedly connected to a fixed base plate, and an X-axis ball screw drive guide is provided on one side of the bottom of the fixed base plate, and the bottom of the X-axis ball screw drive guide is fixedly connected to a second digital dial indicator, and a number of rough leveling assemblies are evenly distributed and fixedly connected on the other side of the bottom of the fixed base plate, a Y-axis ball screw drive guide is provided on the left end of the fixed base plate, and the bottom of the Y-axis ball screw drive guide is fixedly connected to a first digital dial indicator, and a battery pack is also provided on the front side of the fixed base plate.

[0010] Furthermore, the rough leveling assembly includes a column fixedly connected to the bottom of the fixed base plate, the bottom of the column is fixedly connected to the cylinder, two groups of limit plates are symmetrically fixedly connected to the middle position inside the cylinder, two groups of springs are symmetrically fixedly installed on opposite sides of the two groups of limit plates, a movable plate is fixedly connected to the middle position of the two groups of springs, and the movable plate is slidably connected to the inner wall of the cylinder, the middle position of the movable plate is fixedly connected to a push rod, the upper and lower ends of the push rod respectively pass through the two groups of limit plates and are slidably connected to the limit plates; the top end of the push rod is fixedly connected to the extrusion plate, and the top surface of the cylinder is fixedly connected to the pressure sensor; the bottom end of the push rod extends to the outside of the cylinder and is fixedly connected to the resistance ball.

[0011] Furthermore, the fourth axis assembly includes a tailstock and a fixed seat fixedly connected to the X-axis movable guide rail, a bridge plate is rotatably connected between the tailstock and the fixed seat, and a fourth axis rotating motor is provided on one side of the tailstock to drive the bridge plate to rotate.

[0012] Furthermore, the upper surface of the X-axis movable guide rail is also fixedly connected to a hydraulic support assembly corresponding to the middle position of the bridge plate. The hydraulic support assembly includes a base fixedly connected to the upper surface of the X-axis movable guide rail, and a number of hydraulic support rods are evenly fixed on the base. The upper ends of the hydraulic support rods are commonly provided with flexible gaskets, and the flexible gaskets are made of polyurethane, and the flexible gaskets are pressed against the lower surface of the bridge plate.

[0013] Furthermore, the processing unit is used to calculate the angle at which the fourth-axis rotating motor needs to adjust the bridge plate based on the levelness data collected in real time by the first digital display dial indicator; and calculate the Y-axis deformation span value S of the bridge plate deformation position based on the deformation data detected by the rough leveling component. Y ; Use the second digital display dial indicator to detect the deformation position X-axial deformation span value S X And the Z-axis coordinate of the maximum deformation point Z M ; Use the Y-axis deformation span value S of the bridge plate deformation positionY And the X-axis deformation span value S X Find the center of the bridge deck deformation position and correspond it to the hydraulic support rod in the corresponding area, and calculate the compensation amount of the hydraulic support rod for compensation.

[0014] Furthermore, the horizontality data collected in real time by the first digital display dial indicator is used to calculate the angle at which the fourth axis rotating motor needs to adjust the bridge plate, including:

[0015] Use the first digital dial indicator to pull the bridge plate a certain distance in the Y-axis direction, assume the spatial coordinates of the first contact point is , and the spatial coordinates of the last contact point is , establish a formula to obtain the axis rotation angle of the bridge plate, and use the fourth-axis rotation motor to make corresponding adjustments.

[0016] Furthermore, based on the deformation data detected by the rough leveling component, the Y-axis deformation span value S of the bridge plate deformation position is calculated. Y ,include:

[0017] Move all the rough leveling components in the Y-axis direction of the bridge plate. If the horizontal reference surface of the bridge plate after preliminary leveling is deformed due to gravity, the pressure sensor pressure signal of the rough leveling component will disappear during the movement. Calculate the Y-axis deformation span value S based on the disappearance time and the moving speed of the rough leveling component. Y .

[0018] Furthermore, the deformation position X-axis deformation span value S is detected by the second digital display dial indicator. X And the Z-axis coordinate of the maximum deformation point Z M ,include:

[0019] Use the X-axis ball screw to drive the guide rail along the X-axis, move the second digital dial indicator in the center of the Y-axis at the deformation point, and obtain the X-axis deformation span value S at the deformation point. X And the Z-axis coordinate of the maximum deformation point Z M .

[0020] Furthermore, the Y-axis deformation span value S of the bridge plate deformation position is used Y And the X-axis deformation span value S X Find the center of the bridge deck deformation and correspond it to the hydraulic support rod in the corresponding area, calculate the compensation amount of the hydraulic support rod and perform compensation, including:

[0021] The processing unit obtains the deformation position Y axis deformation span value S Y And the X-axis deformation span value S X , calculate the deformation position center of the bridge plate, correspond to the hydraulic support rod in the corresponding area, calculate the Z-axis hydraulic support rod compensation required for the deformation position and perform compensation.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This application sets up a horizontal leveling component and a hydraulic support component. First, when testing the flatness of the reference surface of a large bridge deck, there is no need to manually use a dial indicator to test the flatness in different areas multiple times. Automated testing is achieved, and the operating steps are simplified. At the same time, the subjective degree error caused by manual testing is avoided, and the leveling efficiency is improved. At the same time, the hydraulic support component is set up to provide compensatory support for the bridge deck, which further avoids the deformation of the bridge deck due to gravity and improves the CNC machining accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0025] Figure 2 This is a schematic structural diagram of the fourth shaft assembly of the present invention;

[0026] Figure 3 This is an enlarged structural diagram of the horizontal leveling assembly of the present invention;

[0027] Figure 4 This is a schematic cross-sectional structure diagram of the rough leveling assembly of the present invention;

[0028] Figure 5 This is a schematic structural diagram of the hydraulic support assembly of the present invention.

[0029] Description of the numbers in the figure:

[0030] 1. CNC center main body; 2. X-axis moving guide rail; 3. Y-axis moving guide rail;

[0031] 4. Fourth axis assembly; 41. Tailstock; 42. Bridge plate; 43. Fixed seat; 44. Fourth axis rotating motor;

[0032] 5. Horizontal leveling assembly; 51. Connecting portion; 52. Main connecting rod; 53. Y-axis ball screw drive guide; 54. First digital display dial indicator;

[0033] 55, coarse leveling assembly; 551, column; 552, cylinder; 553, limit plate; 554, movable plate; 556, resistance ball; 557, ejector rod; 560, spring; 561, extrusion plate; 562, pressure sensor;

[0034] 56. Battery pack; 57. Fixed base plate; 58. X-axis ball screw drive guide; 59. Second digital display dial indicator;

[0035] 6. Tool spindle; 7. Tool drive module; 8. Z-axis moving guide rail;

[0036] 9. Hydraulic support assembly; 91. Flexible gasket; 92. Hydraulic support rod; 93. Base. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] See also Figures 1 to 5 A four-axis unit CNC machining center includes a CNC center body 1, a Y-axis movable guide rail 3 is provided on the bottom platform of the CNC center body 1, and an X-axis movable guide rail 2 is fixedly provided on the Y-axis movable guide rail 3; a Z-axis movable guide rail 8 is fixedly connected to one side of the CNC center body 1, and the CNC center body 1 is movably connected to a tool drive module 7 through the Z-axis movable guide rail 8, and the lower end of the tool drive module 7 is fixedly connected to a tool spindle 6;

[0039] The fourth axis assembly 4 is fixedly connected to the X-axis movable guide rail 2 , and the lower end of the tool spindle 6 is detachably connected to a horizontal leveling assembly 5 for leveling the fourth axis assembly 4 .

[0040] like Figure 3 and Figure 4 As shown, the horizontal leveling assembly 5 includes a main connecting rod 52 and a processing unit, and the main connecting rod 52 is provided with a connecting portion 51 and is detachably connected to the tool spindle 6 through the connecting portion 51, and the connecting portion 51 and the tool spindle 6 can be optionally connected by a threaded connection or a hydraulic clamping connection; the bottom of the main connecting rod 52 is fixedly connected to a fixed base plate 57, and an X-axis ball screw drive guide rail 58 is provided on one side of the bottom of the fixed base plate 57, and the bottom of the X-axis ball screw drive guide rail 58 is fixedly connected to a second digital dial indicator 59, and a number of rough leveling assemblies 55 are evenly distributed and fixedly connected on the other side of the bottom of the fixed base plate 57, a Y-axis ball screw drive guide rail 53 is provided on the left end of the fixed base plate 57, and the bottom of the Y-axis ball screw drive guide rail 53 is fixedly connected to the first digital dial indicator 54, and a battery pack 56 is also provided on the front side of the fixed base plate 57.

[0041] like Figure 4As shown, the rough leveling assembly 55 includes a column 551 fixedly connected to the bottom of the fixed base plate 57, the bottom of the column 551 is fixedly connected to the cylinder 552, and two groups of limit plates 553 are symmetrically fixedly installed at the middle position inside the cylinder 552, and two groups of springs 560 are symmetrically fixedly installed on the opposite sides of the two groups of limit plates 553. A movable plate 554 is fixedly connected at the middle position of the two groups of springs 560, and the movable plate 554 is slidably connected to the inner wall of the cylinder 552, and the middle position of the movable plate 554 is fixedly connected to the push rod 557, and the upper and lower ends of the push rod 557 respectively pass through the two groups of limit plates 553 and are slidably connected to the limit plates 553; the top end of the push rod 557 is fixedly connected to the extrusion plate 561, and the top surface of the cylinder 552 is fixedly connected to the pressure sensor 562; the bottom end of the push rod 557 extends to the outside of the cylinder 552 and is fixedly connected to the contact ball 556.

[0042] like Figure 2 As shown, the fourth axis assembly 4 includes a tailstock 41 and a fixed seat 43 fixed on the X-axis movable guide rail 2, a bridge plate 42 is rotatably connected between the tailstock 41 and the fixed seat 43, and a fourth axis rotating motor 44 is provided on one side of the tailstock 41 to drive the bridge plate 42 to rotate.

[0043] like Figure 5 As shown, the upper surface of the X-axis movable guide rail 2 is also fixedly connected to the middle position of the bridge plate 42, and the hydraulic support assembly 9 includes a base 93 fixedly connected to the upper surface of the X-axis movable guide rail 2. A number of hydraulic support rods 92 are evenly fixedly distributed on the base 93. The upper ends of the hydraulic support rods 92 are commonly provided with flexible gaskets 91, and the flexible gaskets 91 are made of polyurethane and are used to disperse contact stress, and the flexible gaskets 91 are pressed against the lower surface of the bridge plate 42.

[0044] The processing unit is used to calculate the angle that the fourth axis rotating motor 44 needs to adjust the bridge plate 42 based on the levelness data collected in real time by the first digital display dial indicator 54; and calculate the Y-axis deformation span value S of the deformation position of the bridge plate 42 based on the deformation data detected by the rough leveling component 55. Y ; Detect the deformation position X-axial deformation span value S through the second digital display dial indicator 59 X And the Z-axis coordinate of the maximum deformation point Z M ; Using the Y-axis deformation span value S of the bridge plate 42 deformation position Y And the X-axis deformation span value S X The center of the deformation position of the bridge plate 42 is found and corresponds to the hydraulic support rod 92 in the corresponding area, and the compensation amount of the hydraulic support rod 92 is calculated and compensated.

[0045] By adopting the above technical solution, when leveling the bridge plate 42, first, according to the traditional method, the base surface (upper surface) of the bridge plate 42 is evenly divided into different areas at intervals of 500 mm. After the division is completed, the leveling assembly 5 is installed on the tool spindle 6, and the leveling operation is started using the leveling assembly 5. Specifically,

[0046] First, a telescopic rod is provided between the first digital dial indicator 54 and the Y-axis ball screw drive guide 53, and the telescopic rod is used to move downward so that the first digital dial indicator 54 moves downward to contact the base surface of the bridge plate 42 (at this time, the rough leveling component 55 does not contact the base surface of the bridge plate 42), and the first digital dial indicator 54 is cleared, and then the control system controls the Y-axis ball screw drive guide 53 to pull the first digital dial indicator 54 from the initial contact point to a certain distance in the Y-axis direction of the bridge plate 42, and records the coordinates of the initial contact point and the final contact point. The processing unit is used to calculate the angle that the fourth-axis rotation motor 44 needs to adjust the bridge plate 42, and then the CNC center system obtains the calculation result of the processing unit and controls the fourth-axis rotation motor 44 to work, driving the bridge plate 42 to rotate to the corresponding angle, so that the flatness error of the base surface of the bridge plate 42 is less than or equal to 0.02 mm, completing the preliminary leveling, and the telescopic rod is used to drive the first digital dial indicator 54 to reset;

[0047] Then, the Z-axis movable guide rail 8 is used to move the tool drive module 7 downward, so that the horizontal leveling component 5 fixedly connected to the tool drive module 7 moves downward, and the contact ball 556 contacts the base surface of the bridge plate 42. It should be noted here that in this application, under the state of no external force, the distance between the extrusion plate 561 and the pressure sensor 562 is set to 0.02mm (the two springs 560 are both in a compressed state when not subjected to external force, and have a large stiffness coefficient, so that the 0.02mm distance is stably maintained). The Z-axis movable guide rail 8 is continued to be used to drive the horizontal leveling component 5 to move downward, so that the extrusion plate 561 contacts and squeezes the pressure sensor 562. After the pressure sensor 562 detects the pressure signal, it stops moving downward, and then the control system controls the Y-axis movable guide rail 3 to drive the bridge plate 42 to move in the Y-axis direction, so that the contact balls 556 of several groups of rough leveling components 55 are pulled along the Y-axis direction on the base surface of the bridge plate 42. If there is any weight on the base surface of the bridge plate 42 The deformation position caused by the force, when the contact ball 556 of the coarse leveling component 55 passes the deformation position (the deformation depth is greater than or equal to 0.02mm), since several coarse leveling components 55 are distributed in the X direction and are arranged in a one-to-one correspondence with the base surface of the bridge plate 42 according to the 500mm interval, and the coarse leveling component 55 is arranged in the middle position of the 500mm interval area, the contact ball 556 in the deformation area is no longer squeezed by the bridge plate 42. Under the action of the elastic potential energy of the spring 560, the contact ball 556 will move downward, and the push rod 557 will be used to drive the extrusion plate 561 to move down to a state without force, the pressure sensor 562 is not squeezed, and the pressure signal disappears; when the contact ball 556 moves out of the deformation position, the pressure sensor 562 is subjected to pressure again, and a pressure signal appears. According to the time when the pressure signal disappears and the speed at which the Y-axis moving guide rail 3 drives the horizontal leveling component 5, the deformation position Y-axis deformation span value S is calculated. Y Then, the Y-axis moving guide rail 3 drives the fourth axis assembly 4 to move, so that the second digital display dial indicator 59 on the horizontal leveling assembly 5 moves to the middle position of the Y-axis deformation span of the deformation position, and the control system controls the X-axis ball screw driving guide rail 58 to drive the second digital display dial indicator 59 to move along the X-axis (the second digital display dial indicator 59 and the X-axis ball screw driving guide rail 58 are also connected by a telescopic rod, and the telescopic rod is used to move downward so that the second digital display dial indicator 59 begins to contact the base surface of the bridge plate 42, and the first point where the second digital display dial indicator 59 begins to contact the base surface of the bridge plate 42 is set to zero and cleared. At this time, the rough leveling assembly 55 does not contact the base surface of the bridge plate 42). As the second digital display dial indicator 59 moves, the deformation position X-axis deformation span value S is detected. X And the Z-axis coordinate of the maximum deformation point Z M , using the Y-axis deformation span value S of the bridge plate 42 deformation position Y And the X-axis deformation span value S XFind the deformation center of the bridge plate 42 and correspond it to the hydraulic support rod 92 in the corresponding area, calculate the upward compensation amount of the hydraulic support rod 92, and make compensation so that the overall flatness error of the base surface of the bridge plate 42 is less than 0.02mm, completing the leveling of the flatness of the base surface of the bridge plate 42.

[0048] In some implementations, the levelness data collected in real time by the first digital dial indicator 54 is used to calculate the angle at which the fourth axis rotary motor 44 needs to adjust the bridge plate 42 ;

[0049] By adopting the above technical solution, the first digital display dial indicator 54 is pulled a certain distance in the Y-axis direction of the bridge plate 42. The spatial coordinates of the first contact point are set as X0, Y1, and Z1, and the spatial coordinates of the last contact point are set as X0, Y2, and Z2. It should be noted that the spatial coordinates can be obtained by a simple calculation based on the machining center coordinate system combined with the displacement distance of the first digital display dial indicator 54. The CNC system can directly output the relevant coordinates based on this. The displacement distance of the first digital display dial indicator 54 can be directly obtained by the distance that the system controls the Y-axis ball screw to drive the guide rail 53 to move, and a calculation formula is established:

[0050]

[0051] Among them, θ is the tilt angle between the bridge plate 42 and the central rotation axis. The above calculation formula is used to obtain the axial rotation angle of the bridge plate 42, and the CNC system of the CNC center controls the fourth-axis rotation motor 44 to rotate the corresponding angle, so that the base surface of the bridge plate 42 maintains a horizontality error of less than 0.02mm.

[0052] In some implementations, the Y-axis deformation span value S of the bridge plate 42 is calculated based on the deformation data detected by the rough leveling assembly 55. Y , move all the rough leveling components 55 in the Y-axis direction of the bridge plate 42. If the horizontal reference surface of the bridge plate 42 after preliminary leveling is deformed due to gravity, the pressure signal of the pressure sensor 562 will disappear during the movement of the rough leveling component 55. Calculate the Y-axis deformation span value S based on the disappearance time and the moving speed of the rough leveling component 55. Y .

[0053] By adopting the above technical solution, assuming that the longest period of time during which the pressure signal of the pressure sensor 562 disappears is T1, and the speed at which the Y-axis moving guide rail 3 drives the horizontal leveling assembly 5 is V1, a calculation formula is established:

[0054]

[0055] According to the above formula, the deformation span value S of the Y axis at the deformation position is obtained. Y .

[0056] In some implementations, the second digital dial indicator 59 is used to detect the deformation position X-axis deformation span value S X And the Z-axis coordinate of the maximum deformation point Z M , use the X-axis ball screw to drive the guide rail 58 along the X-axis, and move the second digital display dial indicator 59 in the middle direction of the Y-axis deformation span at the deformation point to obtain the X-axis deformation span value S at the deformation point X And the Z-axis coordinate of the maximum deformation point Z M .

[0057] By adopting the above technical solution, assuming that the time from the second digital display dial indicator 59 detecting the deformation reading to the deformation reading disappearing is T2, and the X-axis ball screw driving guide 58 drives the second digital display dial indicator 59 to move along the X-axis at a speed of V2, a calculation formula is established:

[0058]

[0059] According to the above formula, the deformation position X-axial deformation span value S is obtained X .

[0060] It should be noted that the second digital display dial indicator 59, the first digital display dial indicator 54, and the pressure sensor 562 are all provided with a signal transceiver module, which can transmit and receive signals with the numerical control system and the processing unit.

[0061] In some implementations, the Y-axis deformation span value S of the bridge plate 42 deformation position is used. Y And the X-axis deformation span value S X Find the center of the deformation position of the bridge plate 42 and correspond it to the hydraulic support rod 92 in the corresponding area, calculate the compensation amount of the hydraulic support rod 92 and perform compensation, and the processing unit obtains the deformation span value S of the Y axis of the deformation position Y And the X-axis deformation span value S X , calculate the deformation position center of the bridge plate 42, correspond to the hydraulic support rod 92 in the corresponding area, calculate the compensation amount of the Z-axis hydraulic support rod 92 required for the deformation position and perform compensation.

[0062] By adopting the above technical solution, the deformation span value S of the Y axis of the deformation position is Y And the X-axis deformation span value S X , take 1 / 2 span respectively, the intersection point is approximately taken as the center point of deformation position, and the X-axis and Y-axis coordinates of the corresponding center point are set as X C 、Y C , which can be obtained by combining the CNC system coordinate system with the deformation position Y-axis deformation span value S Y And the X-axis deformation span value S XAfter the coordinates of the center point of the deformation position are determined by a simple calculation of the numerical control system, which will not be described in detail here, the coordinates are mapped to the hydraulic support rod 92 closest to the coordinates. It should be noted that the hydraulic support rods 92 are arranged at intervals of 500 mm, corresponding to the areas of the base surface of the bridge deck 42 evenly divided at 500 mm intervals. Since the deformation of the bridge deck 42 caused by gravity mainly occurs at the mid-span position of the bridge deck 42, the hydraulic support assembly 9 is arranged along the mid-span position.

[0063] At the same time, obtain the Z-axis coordinate of the maximum deformation point M , Z M It can be taken as the maximum value detected by the second digital display dial indicator 59 in the deformation area, and the calculation formula is established:

[0064]

[0065] Where ∆H is the compensation required by hydraulic support rods 92 to compensate for the deformation of bridge deck 42, K is a correction coefficient ranging from 0.65 to 0.75, and E is the elastic modulus and I is the moment of inertia of the section, both of which can be determined experimentally. Based on the above formula, the compensation required by the hydraulic support rod 92 closest to the center of deformation to compensate for the deformation of bridge deck 42 is calculated. The hydraulic support rods 92 are then driven to compensate, adjusting the deformation position, ensuring leveling, and further improving machining accuracy.

[0066] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any person skilled in the art who, within the technical scope disclosed by the present invention, makes equivalent substitutions or modifications based on the technical solutions and improved concepts of the present invention shall be covered by the scope of protection of the present invention.

Claims

1. A four-axis CNC machining center, comprising a CNC center body, a Y-axis movable guide rail provided on the bottom platform of the CNC center body, and an X-axis movable guide rail fixedly provided on the Y-axis movable guide rail; a Z-axis movable guide rail fixedly connected to one side of the CNC center body, and the CNC center body movably connected to a tool drive module via the Z-axis movable guide rail, and the lower end of the tool drive module fixedly connected to a tool spindle; Its characteristics are: The fourth axis assembly is fixedly connected to the X-axis moving guide rail, and the lower end of the tool spindle is detachably connected to a leveling assembly for leveling the fourth axis assembly; The horizontal leveling assembly includes a main connecting rod and a processing unit. The main connecting rod is provided with a connecting portion and is detachably connected to the tool spindle through the connecting portion. The connecting portion and the tool spindle can be connected by either a threaded connection or a hydraulic clamping connection. The bottom of the main connecting rod is fixedly connected to a fixed base plate. An X-axis ball screw drive guide is provided on one side of the bottom of the fixed base plate, and a second digital dial indicator is fixedly connected to the bottom of the X-axis ball screw drive guide. A number of coarse leveling assemblies are evenly distributed and fixedly connected on the other side of the bottom of the fixed base plate. A Y-axis ball screw drive guide is provided on the left end of the fixed base plate, and a first digital dial indicator is fixedly connected to the bottom of the Y-axis ball screw drive guide. A battery pack is also provided on the front side of the fixed base plate. The rough leveling assembly includes a column fixedly connected to the bottom of the fixed base plate, the bottom of the column is fixedly connected to the cylinder, two sets of limit plates are symmetrically fixedly connected to the middle position of the cylinder, two sets of springs are symmetrically fixedly installed on opposite sides of the two sets of limit plates, a movable plate is fixedly connected to the middle position of the two sets of springs, and the movable plate is slidably connected to the inner wall of the cylinder, the middle position of the movable plate is fixedly connected to the ejector rod, the upper and lower ends of the ejector rod respectively pass through the two sets of limit plates and are slidably connected to the limit plates; the top end of the ejector rod is fixedly connected to the extrusion plate, and the top surface of the cylinder is fixedly connected to the pressure sensor; the bottom end of the ejector rod extends to the outside of the cylinder and is fixedly connected to the contact ball; The fourth axis assembly includes a tailstock and a fixed seat fixed on the X-axis moving guide rail, a bridge plate is rotatably connected between the tailstock and the fixed seat, and a fourth axis rotation motor is provided on one side of the tailstock to drive the bridge plate to rotate; A hydraulic support assembly is also fixedly connected to the middle position of the bridge plate on the upper surface of the X-axis movable guide rail. The hydraulic support assembly includes a base fixedly connected to the upper surface of the X-axis movable guide rail, and a plurality of hydraulic support rods are evenly fixed on the base. The processing unit is used to calculate the angle that the fourth axis rotating motor needs to adjust the bridge plate based on the horizontal data collected in real time by the first digital display dial indicator; and calculate the Y-axis deformation span value S of the bridge plate deformation position based on the deformation data detected by the rough leveling component. Y ; Use the second digital display dial indicator to detect the deformation position X-axial deformation span value S X And the Z-axis coordinate of the maximum deformation point Z M ; Use the Y-axis deformation span value S of the bridge plate deformation position Y And the X-axis deformation span value S X Find the center of the bridge deck deformation position and correspond it to the hydraulic support rod in the corresponding area, and calculate the compensation amount of the hydraulic support rod for compensation.

2. The four-axis unit CNC machining center according to claim 1, characterized in that: A flexible gasket is provided on the upper end of the hydraulic support rod, and the flexible gasket is made of polyurethane material, and the flexible gasket is pressed against the lower surface of the bridge plate.

3. The four-axis unit CNC machining center according to claim 1, characterized in that: The horizontality data collected in real time by the first digital display dial indicator is used to calculate the angle at which the fourth axis rotating motor needs to adjust the bridge plate, including: Use the first digital dial indicator to pull the bridge plate a certain distance in the Y-axis direction. Assume that the spatial coordinates of the first contact point are X0, Y1, Z1, and the spatial coordinates of the last contact point are X0, Y2, Z2. Establish a formula to obtain the axis rotation angle of the bridge plate, and use the fourth-axis rotary motor to make corresponding adjustments.

4. The four-axis unit CNC machining center according to claim 1, characterized in that: According to the deformation data detected by the rough leveling component, the Y-axis deformation span value S of the bridge plate deformation position is calculated. Y ,include: Move all the rough leveling components in the Y-axis direction of the bridge plate. If the horizontal reference surface of the bridge plate after preliminary leveling is deformed due to gravity, the pressure sensor pressure signal of the rough leveling component will disappear during the movement. Calculate the Y-axis deformation span value S based on the disappearance time and the moving speed of the rough leveling component. Y .

5. The four-axis unit CNC machining center according to claim 1, characterized in that: The deformation position X-axis deformation span value S is detected by the second digital display dial indicator X And the Z-axis coordinate of the maximum deformation point Z M ,include: Use the X-axis ball screw to drive the guide rail along the X-axis, move the second digital dial indicator in the center of the Y-axis at the deformation point, and obtain the X-axis deformation span value S at the deformation point. X And the Z-axis coordinate of the maximum deformation point Z M .

6. The four-axis unit CNC machining center according to claim 1, characterized in that: Using the Y-axis deformation span value S of the bridge plate deformation position Y And the X-axis deformation span value S X Find the center of the bridge deck deformation and correspond it to the hydraulic support rod in the corresponding area, calculate the compensation amount of the hydraulic support rod and perform compensation, including: The processing unit obtains the deformation position Y axis deformation span value S Y And the X-axis deformation span value S X , calculate the deformation position center of the bridge plate, correspond to the hydraulic support rod in the corresponding area, calculate the Z-axis hydraulic support rod compensation required for the deformation position and perform compensation.

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