A turning and milling combined device of a gantry machining center

Abstract

This invention relates to the field of milling-turning composite machine tool technology, specifically a milling-turning composite device for a gantry machining center. It includes a machine tool body, a spindle, a Z-axis mounting bracket, and a feed unit. The feed unit is mounted on the machine tool body, the Z-axis mounting bracket is slidably connected to the feed unit, and the spindle is rotatably connected within the Z-axis mounting bracket. The spindle includes a mounting section and a reinforcing section, with the mounting section located above the reinforcing section. This invention improves the long-term accuracy retention and service life of the spindle without significantly altering the main structure of the machine tool or sacrificing the core milling performance. It expands the milling-turning composite machining capabilities and application range of gantry machining centers, providing reliable technical support for efficient and high-precision machining of complex workpieces.

Description

Technical Field

[0001] This invention relates to the field of mill-turning composite machine tool technology, specifically a mill-turning composite device for a gantry machining center. Background Technology

[0002] For complex workpieces, completing all cutting requirements in a single setup is an important factor in ensuring machining accuracy. Gantry machining centers, due to their high rigidity, large stroke, and strong load-bearing capacity, are commonly used milling and turning composite machine tools for machining large plate, frame, and complex curved surface parts.

[0003] Currently, there are two main technical approaches to achieving milling-turning composite functions in gantry machining centers: The first involves adding a dedicated, high-rigidity turning turret or spindle box to the gantry beam or ram. This approach offers strong turning capabilities but results in a complex machine tool structure, high cost, reduced dynamic balance, and potential spatial and functional interference between the two spindle systems, making it not an economically efficient choice for all applications. The second approach does not add a separate turning unit. Instead, the turning tool is mounted on the existing milling spindle, utilizing its high-speed characteristics for rotary cutting. Simultaneously, the workpiece is clamped on a precision CNC rotary table, and various turning operations are completed through interpolation between the C-axis and the machine tool's linear axes. This approach offers significant advantages such as simple structure, lower cost, and flexible function switching.

[0004] However, the second technical solution has the following drawbacks, which limit the machining performance and application range of gantry machining centers: the preload setting, lubrication, and cooling system of the standard high-speed milling spindle bearings are all optimized for high-speed, radial load-dominant working conditions. When used for turning, the bearings need to withstand axial and torsional loads for extended periods, which is seriously inconsistent with the original design conditions. This will accelerate bearing fatigue, pose a risk of premature failure, and affect the long-term accuracy retention and service life of the spindle.

[0005] Therefore, existing gantry machining centers using the second technical solution for turning operations suffer from significant shortcomings in dynamic performance, machining accuracy, reliability, and process capability due to the structural mismatch between the milling spindle system and turning conditions. The industry urgently needs a technical solution that, without significantly altering the machine tool's main structure or sacrificing core milling performance, fundamentally enhances the milling spindle's vibration resistance, thermal stability, and dynamic and static stiffness in turning mode, achieving efficient, high-precision, and highly reliable milling-turning composite machining. Summary of the Invention

[0006] The purpose of this invention is to provide a milling and turning composite device for gantry machining centers, in order to solve the problem that when existing gantry machining centers are performing turning operations, the structural mismatch between the milling spindle system and the turning conditions limits the bearings of the machine tool spindle to withstand long-term conditions dominated by axial and torsional loads, which accelerates bearing fatigue, poses a risk of premature failure, and affects the long-term accuracy maintenance and service life of the spindle.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A milling and turning compound device for a gantry machining center includes a machine tool body, a spindle, a Z-axis mounting bracket, and a feed unit. The feed unit is mounted on the machine tool body, and the Z-axis mounting bracket is slidably connected to the feed unit. The spindle is rotatably connected within the Z-axis mounting bracket. The spindle includes a mounting section and a reinforcing section. The mounting section is located above the reinforcing section. A first raceway is formed on the outer wall of the reinforcing section. A sleeve is provided inside the Z-axis mounting bracket and is coaxially arranged with the reinforcing section. A second raceway is formed on the inner wall of the sleeve, and multiple balls are rolled within the second raceway. A clutch assembly is fixedly connected inside the Z-axis mounting bracket. The upper end of the clutch assembly is fixedly connected to the sleeve, and the clutch assembly is used to drive the sleeve to move up and down. The clutch assembly has two working positions: a top dead center and a bottom dead center. When the clutch assembly is at the bottom dead center, the balls are rolled within the first raceway; when the clutch assembly is at the top dead center, the balls are disengaged from the first raceway.

[0009] By setting a reinforcing section on the spindle and installing a sleeve in the Z-axis mounting bracket, the sleeve and the reinforcing section are connected by rolling balls. Simultaneously, a clutch assembly controls the up-and-down movement of the sleeve, thereby enabling the balls to contact or disengage from the first raceway. This structure ensures that in milling mode, the clutch assembly is at top dead center, the balls are disengaged from the first raceway, and there is no direct contact between the reinforcing section and the sleeve. The spindle's rotation is primarily supported by its own bearing system, guaranteeing high-speed rotation performance and accuracy during milling. In turning mode, the clutch assembly switches to bottom dead center, and the balls are connected to the first raceway. At this time, the sleeve provides additional axial and radial support to the reinforcing section of the spindle through the balls, effectively enhancing the spindle's vibration resistance, thermal stability, and dynamic and static stiffness under turning conditions. Without significantly altering the main structure of the machine tool or sacrificing the core milling performance, this invention solves the structural mismatch between the milling spindle system and the turning conditions in existing gantry machining centers. It avoids the risk of accelerated fatigue and premature failure of the spindle bearings due to long-term exposure to unreasonable axial and torsional loads, significantly improves the long-term accuracy retention and service life of the spindle, expands the milling-turning composite machining capabilities and application range of gantry machining centers, and provides reliable technical support for the efficient and high-precision machining of complex workpieces.

[0010] Preferably, the clutch assembly includes a piston cylinder seat, a piston rod, and a limiting pin. The piston cylinder seat is fixedly installed on the lower end of the Z-axis mounting bracket and is coaxially arranged with the main shaft. The upper end face of the piston cylinder seat has multiple piston holes, which are vertically arranged and evenly distributed around the axis of the main shaft. The multiple piston holes are interconnected. The piston rod is slidably connected to the piston holes. A connecting flange is provided on the outer wall of the sleeve. The upper end of the piston rod is fixedly connected to the connecting flange. The limiting pin is fixedly connected to the upper end face of the piston cylinder seat and is vertically arranged. A limiting pin is provided between every two adjacent piston rods. The connecting flange has multiple limiting holes that penetrate the upper and lower sides. The multiple limiting pins are coaxially arranged with the multiple limiting pins and are slidably connected to the limiting holes.

[0011] The clutch assembly, consisting of a piston cylinder seat, piston rod, and limit pin, controls the vertical movement of the sleeve. The piston cylinder seat is fixed to the lower end of the Z-axis mounting bracket and is coaxial with the spindle. Multiple piston holes are evenly distributed around the circumference of the spindle axis and are interconnected, ensuring that the piston rod is subjected to uniform force during sliding and avoiding jamming or displacement caused by uneven force. The upper end of the piston rod is fixedly connected to the connecting flange on the outer wall of the sleeve. When the piston rod slides in the piston hole, it can drive the sleeve to move up and down synchronously. When the piston is at the bottom dead center, the torque of the spindle rotation can be transmitted to the sleeve through the balls. The limit pin restricts the rotational freedom of the sleeve, ensuring that the sleeve can only move vertically in a straight line under the drive of the piston rod and will not rotate around the spindle axis. This ensures a stable rolling connection between the balls and the first and second raceways, improving the support rigidity and stability of the spindle in turning mode. The limiting hole and the limiting pin on the connecting flange are slidably connected, which not only enhances the stability of the structure, but also improves the reliability of the clutch assembly. This allows the spindle to quickly and accurately adjust the position of the sleeve when switching between milling and turning modes, thereby achieving contact or disengagement of the ball and the first raceway, meeting the needs of different machining modes.

[0012] Preferably, both the first raceway and the second raceway are arc surfaces, and the arc-shaped openings of the first raceway and the second raceway are arranged opposite to each other. An isolation surface is provided on the upper side of the first raceway. The isolation surface is a conical surface, and the large end of the isolation surface is connected to the first raceway.

[0013] By designing raceways one and two as curved surfaces with their arc-shaped openings facing each other, this structure allows the balls to better conform to the raceways during rolling, reducing rolling resistance and improving rolling efficiency. Furthermore, a conical isolation surface is provided on the upper side of raceway one, with its larger end connected to raceway one. In milling mode, when the balls and sleeve are at top dead center, the isolation surface prevents the balls from contacting the spindle at top dead center, effectively preventing friction and wear caused by accidental contact and ensuring the high-speed rotation performance of the spindle during milling. In turning mode, when the balls contact raceway one, the isolation surface acts as a guide, and this gap facilitates the flow of lubricating oil, further reducing friction and heat generation during rolling and improving the spindle's vibration resistance and thermal stability.

[0014] Preferably, a retainer is provided between the sleeve and the reinforcing section. The retainer is coaxial with the sleeve. The side wall of the retainer has multiple through holes that penetrate the inner and outer sides of the retainer. The multiple through holes are arranged in a circumferential array along the central axis of the retainer. Multiple balls are respectively rolled and installed in the multiple through holes. The outer side wall of the retainer has a limiting flange. The inner side wall of the sleeve has a limiting groove. The limiting groove is located on the lower side of the second raceway, and the upper side of the limiting groove is connected to the lower end of the second raceway. The limiting flange extends into the limiting groove. When the balls are rolled and connected with the first raceway, an isolation gap is formed between the lower end face of the limiting flange and the bottom wall of the limiting groove. The height of the isolation gap is 1-2 mm.

[0015] By setting a cage between the sleeve and the reinforced section, and with the cage coaxial with the sleeve, the stability of the balls during rolling is ensured. Multiple through holes on the side wall of the cage provide precise installation positions for the balls, allowing them to be evenly distributed between the sleeve and the reinforced section, further improving the smoothness of rolling. The balls are rolled and installed in the through holes. When the spindle is subjected to axial and torsional loads in turning mode, the balls can effectively transmit these loads. At the same time, the cage plays a role in fixing and supporting the balls, preventing them from falling off or shifting.

[0016] Furthermore, the limiting flange on the outer wall of the cage extends into the limiting groove on the inner wall of the sleeve, thereby restricting the axial movement freedom of the cage and ensuring the relative position stability between the cage and the sleeve. When the ball rolls into contact with the first raceway, the isolation gap formed between the lower end face of the limiting flange and the bottom wall of the limiting groove has a height of 1-2 mm. This isolation gap not only ensures the flexibility of the ball during rolling but also prevents vibration and noise caused by excessive gap, further improving the vibration resistance and thermal stability of the spindle in turning mode.

[0017] Preferably, an installation groove is provided on the side wall of the limiting groove, the installation groove is coaxial with the sleeve, a permanent magnet ring is provided in the installation groove, and the permanent magnet ring is fixedly connected to the sleeve.

[0018] By creating a mounting groove coaxial with the sleeve on the side wall of the limiting groove, and installing a permanent magnet ring fixedly connected to the sleeve within the mounting groove, the magnetic field generated by the permanent magnet ring can exert a magnetic attraction force on the cage and balls. This magnetic attraction force can, to some extent, offset the impact of some axial and torsional loads generated by the spindle during turning, further stabilizing the cage's position and preventing it from shifting or wobbling due to large loads. This ensures a stable rolling connection between the balls and raceways one and two, improving the spindle's support rigidity and stability in turning mode, and guaranteeing the accuracy and quality of turning operations. Furthermore, when the piston rod drives the sleeve from the bottom dead center to the top dead center, the permanent magnet ring exerts a magnetic attraction force on the balls, causing them to disengage from raceway one. This ensures that when the piston rod is at top dead center, all balls are disengaged from raceway one, avoiding friction and wear caused by individual balls not completely disengaging, and guaranteeing the spindle's high-speed rotation performance and accuracy in milling mode.

[0019] Preferably, an oil storage groove is provided on the side wall of the limiting groove, the oil storage groove is coaxial with the sleeve, the top wall of the oil storage groove is flush with the top wall of the limiting groove, and the oil storage groove is located on the upper side of the permanent magnet ring.

[0020] By creating an oil reservoir coaxial with the sleeve and flush with its top wall on the side wall of the limiting groove, and positioning it above the permanent magnet ring, the reservoir can store a certain amount of grease. During spindle operation, the grease gradually seeps out from the reservoir, providing continuous lubrication to the cage, balls, and raceways 1 and 2. This effectively reduces friction and wear between components, lowers heat generated by friction, and further improves the spindle's vibration resistance and thermal stability in turning mode, extending the device's service life and ensuring the accuracy and quality of milling-turning machining. Simultaneously, the oil reservoir, in conjunction with the permanent magnet ring, allows the magnetic field generated by the ring to attract iron filings from the grease, preventing them from entering the raceways and damaging the balls and raceways, further ensuring the smoothness and accuracy of spindle operation.

[0021] Preferably, the surfaces of the first raceway, the second raceway, and the balls are all surface-hardened, with the surfaces of the first raceway and the second raceway hardened to HRC58 to HRC62, and the surfaces of the balls hardened to HRC62 to HRC65.

[0022] By surface hardening the surfaces of raceways 1 and 2, and the balls, with the surface hardness of raceways 1 and 2 hardened to HRC58–HRC62 and the surface hardness of the balls hardened to HRC62–HRC65, this treatment significantly improves the surface hardness and wear resistance of the raceways and balls. During long-term spindle operation, especially under large axial and torsional loads in turning mode, the hardened surface effectively resists wear and fatigue, reduces heat and wear particles generated by friction, and thus extends the service life of the raceways and balls. Simultaneously, the higher surface hardness prevents scratches and damage caused by hard particles embedding in the surface, further ensuring the stability and accuracy of the spindle in milling and turning machining. Furthermore, surface hardening treatment improves the corrosion resistance of the raceways and balls, enabling them to maintain good working condition in harsh environments and reducing performance degradation and failure risks caused by corrosion.

[0023] Preferably, multiple through grooves are formed on the inner sidewall of the through hole, and the multiple through grooves penetrate the inner and outer sides of the retainer, and the multiple through grooves are evenly distributed around the central axis of the through hole.

[0024] By creating multiple through grooves on the inner wall of the through hole that penetrate both the inner and outer sides of the cage, and by evenly distributing these grooves along the central axis of the through hole, the design of the through grooves not only facilitates the flow of grease inside the cage, ensuring that the balls are adequately lubricated during rolling and reducing friction and wear, but also allows the grease to better penetrate into the tiny gaps between the balls and the raceways when the spindle is running, forming a stable oil film, further improving the lubrication effect and enhancing the support rigidity and stability of the spindle in turning mode.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. This invention improves the long-term accuracy retention and service life of the spindle by setting a reinforcing section on the spindle and setting a sleeve that cooperates with the reinforcing section in the Z-axis mounting bracket. The sleeve is moved up and down by using a clutch assembly to achieve contact or disengagement between the ball and the first raceway. Without significantly changing the main structure of the machine tool or sacrificing the core milling performance, this invention expands the turning and milling composite machining capabilities and application range of gantry machining centers, and provides a reliable technical guarantee for efficient and high-precision machining of complex workpieces.

[0027] 2. By setting an isolation surface on the upper side of the first raceway, this invention effectively avoids accidental contact between the balls and the spindle in milling mode, preventing friction and wear and ensuring the stability of the spindle's high-speed rotation performance. In turning mode, the isolation surface acts as a guide, promoting the flow of lubricating oil, further reducing rolling friction and heat, enhancing the spindle's vibration resistance and thermal stability, and improving the overall reliability and durability of the device. This provides a more solid technical support for milling and turning composite machining in gantry machining centers.

[0028] 3. This invention, by setting a permanent magnet ring inside the sleeve, generates a magnetic field that attracts the cage and balls, stabilizing the cage's position and preventing it from shifting or wobbling under heavy loads. This ensures a stable rolling connection between the balls and raceways one and two, improving the spindle's support rigidity and stability in turning mode and guaranteeing the accuracy and quality of turning operations. Furthermore, when the piston rod moves the sleeve from the bottom dead center to the top dead center, the permanent magnet ring attracts the balls, causing them to disengage from raceway one. This ensures that all balls are disengaged from raceway one when the piston rod is at the top dead center, avoiding friction and wear caused by incomplete disengagement of individual balls and ensuring the spindle's high-speed rotation performance and accuracy in milling mode. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the turning and milling composite device of the gantry machining center of the present invention;

[0030] Figure 2 This is a schematic diagram of the spindle structure in the milling and turning composite device of the gantry machining center of the present invention;

[0031] Figure 3 This is a full sectional view of the milling and turning composite device of the gantry machining center of the present invention;

[0032] Figure 4 for Figure 3 A magnified view of a section at point A in the middle;

[0033] Figure 5 for Figure 4 A magnified view of a section at point B in the middle;

[0034] Figure 6 This is a diagram showing the state of the piston rod pushing the sleeve to the top dead center.

[0035] Figure 7 for Figure 6 A magnified view of a section at point C;

[0036] Figure 8 This is a schematic diagram of the cage structure.

[0037] In the diagram: 1. Machine tool body; 2. Spindle; 201. Mounting section; 202. Reinforcement section; 203. First raceway; 204. Isolation surface; 3. Z-axis mounting bracket; 4. Feed unit; 5. Sleeve; 501. Second raceway; 502. Connecting flange; 503. Limiting hole; 504. Limiting groove; 505. Mounting groove; 506. Oil reservoir; 6. Ball bearing; 7. Piston cylinder seat; 701. Piston hole; 8. Piston rod; 9. Limiting pin; 10. Cage; 1001. Through hole; 1002. Limiting flange; 1003. Through groove; 11. Permanent magnet ring. Detailed Implementation

[0038] Please see Figures 1 to 8 This invention provides a milling and turning composite device for a gantry machining center, the technical solution of which is as follows:

[0039] Please refer to the milling and turning compound device for a gantry machining center. Figures 1 to 4 The system includes a machine tool body 1, a spindle 2, a Z-axis mounting bracket 3, and a feed unit 4. The feed unit 4 is mounted on the machine tool body 1. The Z-axis mounting bracket 3 is slidably connected to the feed unit 4. The spindle 2 is rotatably connected inside the Z-axis mounting bracket 3. The spindle 2 includes a mounting section 201 and a reinforcing section 202. The mounting section 201 is located above the reinforcing section 202. A raceway 203 is formed on the outer wall of the reinforcing section 202. A sleeve 5 is provided inside the Z-axis mounting bracket 3. The sleeve 5 is connected to the reinforcing section 202. The sleeve 5 is coaxially arranged, and the inner wall of the sleeve 5 is provided with a second raceway 501. Multiple balls 6 are rolled in the second raceway 501. A clutch assembly is fixedly connected in the Z-axis mounting bracket 3. The upper end of the clutch assembly is fixedly connected to the sleeve 5. The clutch assembly is used to drive the sleeve 5 to move up and down. The clutch assembly has two working positions: upper dead point and lower dead point. When the clutch assembly is at the lower dead point, the balls 6 are rolled in the first raceway 203. When the clutch assembly is at the upper dead point, the balls 6 are disengaged from the first raceway 203. The clutch assembly includes a piston cylinder seat 7, a piston rod 8, and a limiting pin 9. The piston cylinder seat 7 is fixedly installed on the lower end of the Z-axis mounting bracket 3. The piston cylinder seat 7 is coaxially arranged with the main shaft 2. The upper end face of the piston cylinder seat 7 has multiple piston holes 701. The piston holes 701 are vertically arranged and are evenly distributed around the axis of the main shaft 2. The multiple piston holes 701 are interconnected. The piston rod 8 is slidably connected in the piston holes 701. The outer wall of the sleeve 5 is provided with a connecting flange 502. The upper end of the piston rod 8 is fixedly connected to the connecting flange 502. The limiting pin 9 is fixedly connected to the upper end face of the piston cylinder seat 7. The limiting pin 9 is vertically arranged and there is a limiting pin 9 between every two adjacent piston rods 8. The connecting flange 502 has multiple limiting holes 503 that penetrate the upper and lower sides. The multiple limiting pins 9 are coaxially arranged with the multiple limiting pins 9 respectively, and the limiting pins 9 are slidably connected in the limiting holes 503.

[0040] Please see Figure 4 , Figure 5 and Figure 8 Both raceway 203 and raceway 501 are curved surfaces, and their curved openings are positioned opposite each other. The surfaces of raceway 203, raceway 501 and ball 6 are all surface-hardened. The surfaces of raceway 203 and raceway 501 are hardened to HRC58 to HRC62, and the surface of ball 6 is hardened to HRC62 to HRC65. An isolation surface 204 is provided on the upper side of raceway 203. The isolation surface 204 is a conical surface, and the large end of the isolation surface 204 is connected to raceway 203. A retainer 10 is provided between the sleeve 5 and the reinforcing section 202. The retainer 10 is coaxial with the sleeve 5. Multiple through holes 1001 are formed on the side wall of the retainer 10, penetrating both the inner and outer sides of the retainer 10. The multiple through holes 1001 are arranged in a circumferential array along the central axis of the retainer 10. Multiple balls 6 are respectively rolled and installed within the multiple through holes 1001. Multiple through grooves 1003 are formed on the inner side wall of the through holes 1001, penetrating both the inner and outer sides of the retainer 10. The multiple through grooves 1003 are evenly distributed along the central axis of the through holes 1001. The outer side wall of the retainer 10 has a limiting... The limiting flange 1002 has a limiting groove 504 on the inner side wall of the sleeve 5. The limiting groove 504 is located on the lower side of the second raceway 501, and the upper side of the limiting groove 504 is connected to the lower end of the second raceway 501. The limiting flange 1002 extends into the limiting groove 504. When the ball 6 is connected to the first raceway 203, an isolation gap is formed between the lower end face of the limiting flange 1002 and the bottom wall of the limiting groove 504. The height of the isolation gap is 2mm. An installation groove 505 is provided on the side wall of the limiting groove 504. The installation groove 505 is coaxial with the sleeve 5. A permanent magnet ring 11 is provided in the installation groove 505. The permanent magnet ring 11 is fixedly connected to the sleeve 5. An oil storage groove 506 is provided on the side wall of the limiting groove 504. The oil storage groove 506 is coaxial with the sleeve 5. The top wall of the oil storage groove 506 is flush with the top wall of the limiting groove 504. The oil storage groove 506 is located on the upper side of the permanent magnet ring 11.

[0041] Working principle: Please refer to Figures 1 to 5 When turning is required, the clutch assembly is at the bottom dead center position, at which point the ball 6 rolls into contact with raceway 203. During the operation of the spindle 2, raceway 203 on the outer wall of the reinforced section 202 and the ball 6 in raceway 501 on the inner wall of the sleeve 5 cooperate with each other. Since both raceways 203 and 501 are curved surfaces with opposing arc openings, the ball 6 can fit well into the raceways, reducing rolling resistance and improving rolling efficiency. At the same time, the tapered isolation surface 204 on the upper side of raceway 203 has a guiding effect when the ball 6 contacts raceway 203 in turning mode, which helps the lubricating oil flow, further reducing friction and heat generation during rolling, and improving the vibration resistance and thermal stability of the spindle 2.

[0042] The retainer 10 between the sleeve 5 and the reinforcing section 202 has multiple through holes 1001 on its side wall, providing precise installation positions for the balls 6. This ensures that the balls 6 are evenly distributed between the sleeve 5 and the reinforcing section 202. The limiting flange 1002 on the outer side wall of the retainer 10 extends into the limiting groove 504 on the inner side wall of the sleeve 5, restricting the axial movement freedom of the retainer 10 and ensuring the relative position stability between the retainer 10 and the sleeve 5. The isolation gap formed between the lower end face of the limiting flange 1002 and the bottom wall of the limiting groove 504 ensures the rolling flexibility of the balls 6 while preventing vibration and noise caused by excessive gap.

[0043] The magnetic field generated by the permanent magnet ring 11 in the mounting groove 505 on the side wall of the limiting groove 504 exerts a magnetic attraction on the cage 10 and the balls 6, which can counteract some of the axial and torsional loads generated by the spindle 2 during turning, stabilize the position of the cage 10, and ensure a stable rolling connection between the balls 6 and the first raceway 203 and the second raceway 501, thereby improving the support rigidity and stability of the spindle 2 in turning mode. Meanwhile, the oil reservoir 506 on the side wall of the limiting groove 504 can store grease. During the operation of the spindle 2, the grease gradually seeps out, providing continuous lubrication to various components, reducing friction and wear, reducing heat generation, and extending the service life of the device. At the same time, the permanent magnet ring 11 can also attract iron filings from the grease, preventing them from entering the raceways and causing damage.

[0044] Please see Figure 6 and Figure 7 When milling is required, the piston rod 8 of the clutch assembly drives the sleeve 5 from the bottom dead center to the top dead center. The permanent magnet ring 11 generates a magnetic attraction force on the ball 6, causing the ball 6 to disengage from the first raceway 203. This ensures that when the piston rod 8 is at the top dead center, all the balls 6 are disengaged from the first raceway 203, avoiding friction and wear caused by individual balls 6 not being completely disengaged, and ensuring the high-speed rotation performance and accuracy of the spindle 2 in milling mode.

[0045] Furthermore, the surface hardening treatment applied to the surfaces of raceway 203 (first raceway), raceway 501 (second raceway), and balls 6 significantly improves their surface hardness and wear resistance. During prolonged operation of the spindle 2, especially under heavy loads in turning mode, this effectively resists wear and fatigue, reduces heat and wear particle generation, extends service life, and prevents hard particles from embedding into the surface, causing scratches and damage. This ensures the stability and accuracy of the spindle 2 in milling and turning operations, while also improving corrosion resistance and reducing performance degradation and failure risks caused by corrosion. The through-groove 1003 on the through-hole 1001 facilitates grease flow within the cage 10, allowing the grease to better penetrate the tiny gaps between the balls 6 and the raceways, forming a stable oil film and further improving lubrication, thus enhancing the support rigidity and stability of the spindle 2 in turning mode.

[0046] The specific embodiment of the present invention has been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the embodiments described above. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and ideas of the present invention should still fall within the protection scope of the present invention.

Claims

1. A milling and turning composite device for a gantry machining center, comprising a machine tool body (1), a spindle (2), a Z-axis mounting bracket (3), and a feed unit (4), wherein the feed unit (4) is mounted on the machine tool body (1), the Z-axis mounting bracket (3) is slidably connected to the feed unit (4), and the spindle (2) is rotatably connected within the Z-axis mounting bracket (3), characterized in that, The main shaft (2) includes a mounting section (201) and a reinforcing section (202). The mounting section (201) is located above the reinforcing section (202). A first raceway (203) is provided on the outer side wall of the reinforcing section (202). A sleeve (5) is provided inside the Z-axis mounting bracket (3). The sleeve (5) is coaxially arranged with the reinforcing section (202). A second raceway (501) is provided on the inner side wall of the sleeve (5). A raceway (501) is provided inside the second raceway (501). The moving connection has multiple balls (6), and the Z-axis mounting bracket (3) is fixedly connected to a clutch assembly. The upper end of the clutch assembly is fixedly connected to the sleeve (5). The clutch assembly is used to drive the sleeve (5) to move up and down. The clutch assembly has two working positions: upper dead point and lower dead point. When the clutch assembly is at the lower dead point, the balls (6) are rolled and connected to the first raceway (203). When the clutch assembly is at the upper dead point, the balls (6) are disengaged from the first raceway (203). The clutch assembly includes a piston cylinder seat (7), a piston rod (8), and a limiting pin (9). The piston cylinder seat (7) is fixedly installed on the lower end of the Z-axis mounting bracket (3). The piston cylinder seat (7) is coaxially arranged with the main shaft (2). The upper end face of the piston cylinder seat (7) is provided with multiple piston holes (701). The piston holes (701) are vertically arranged and the multiple piston holes (701) are evenly distributed around the circumference of the axis of the main shaft (2). The multiple piston holes (701) are interconnected. The piston rod (8) is slidably connected in the piston hole (701). The sleeve (5) A connecting flange (502) is provided on the outer wall of the piston rod (8). The upper end of the piston rod (8) is fixedly connected to the connecting flange (502). The limiting pin (9) is fixedly connected to the upper end face of the piston cylinder seat (7). The limiting pin (9) is vertically arranged, and a limiting pin (9) is provided between every two adjacent piston rods (8). The connecting flange (502) is provided with multiple limiting holes (503) that penetrate the upper and lower sides. Multiple limiting pins (9) are coaxially arranged with multiple limiting pins (9), and the limiting pins (9) are slidably connected in the limiting holes (503). A retainer (10) is provided between the sleeve (5) and the reinforcing section (202). The retainer (10) is coaxial with the sleeve (5). The side wall of the retainer (10) has multiple through holes (1001). The through holes (1001) penetrate the inner and outer sides of the retainer (10). The multiple through holes (1001) are arranged in a circumferential array along the central axis of the retainer (10). Multiple balls (6) are respectively rolled and installed in the multiple through holes (1001). The outer side wall of the retainer (10) is provided with a limiting flange (10). 02), a limiting groove (504) is provided on the inner side wall of the sleeve (5). The limiting groove (504) is located on the lower side of the second raceway (501), and the upper side of the limiting groove (504) is connected to the lower end of the second raceway (501). The limiting flange (1002) extends into the limiting groove (504). When the ball (6) is connected to the first raceway (203) in a rolling connection, an isolation gap is formed between the lower end face of the limiting flange (1002) and the bottom wall of the limiting groove (504). The height of the isolation gap is 1 to 2 mm. The limiting groove (504) has an installation groove (505) on its side wall. The installation groove (505) is coaxial with the sleeve (5). A permanent magnet ring (11) is provided in the installation groove (505). The permanent magnet ring (11) is fixedly connected to the sleeve (5). An oil storage groove (506) is provided on the side wall of the limiting groove (504). The oil storage groove (506) is coaxial with the sleeve (5). The top wall of the oil storage groove (506) is flush with the top wall of the limiting groove (504). The oil storage groove (506) is located on the upper side of the permanent magnet ring (11).

2. The turning-milling combined device of the gantry machining center according to claim 1, characterized in that, Both the first raceway (203) and the second raceway (501) are arc surfaces, and the arc-shaped openings of the first raceway (203) and the second raceway (501) are arranged opposite each other. An isolation surface (204) is provided on the upper side of the first raceway (203). The isolation surface (204) is a conical surface, and the large end of the isolation surface (204) is connected to the first raceway (203).

3. The turning-milling combined device of the gantry machining center according to claim 1, characterized in that, The surfaces of the first raceway (203), the second raceway (501), and the ball (6) are all surface hardened. The surfaces of the first raceway (203) and the second raceway (501) are hardened to HRC58 to HRC62, and the surfaces of the ball (6) are hardened to HRC62 to HRC65.

4. The turning-milling combined device of the gantry machining center according to claim 1, characterized in that, Multiple through grooves (1003) are provided on the inner side wall of the through hole (1001). The multiple through grooves (1003) penetrate the inner and outer sides of the retainer (10). The multiple through grooves (1003) are evenly distributed around the central axis of the through hole (1001).

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