A dual-piston spindle structure

Abstract

This invention relates to a dual-piston spindle structure. A rear piston is located at the rear end of the spindle, and a rotor is housed within the spindle. A pull rod passes through the rotor. The rear piston pushes the pull rod towards the front end of the spindle. An annular rotor disc is located on the outer wall of the rotor, positioned at the front end of the spindle. A front piston ring, which moves axially, is located on the side of the rotor disc facing away from the rear piston. The front piston ring applies an axial reaction force to the rotor disc from the front end of the spindle towards the rear end. This invention, by using a front piston ring at the front end of the spindle to apply an axial reaction force towards the rear end of the spindle to the rotor disc, ensures that during tool release, the axial force generated on the rotor when the rear piston pushes the pull rod is directed towards the front end of the spindle. The axial reaction force is opposite to the axial force, thus the bearing assembly inside the spindle does not bear the axial force, thereby extending the service life of the bearing assembly.

Description

Technical Field

[0001] This invention relates to spindles, and more specifically to a dual-piston spindle structure. Background Technology

[0002] A machine tool spindle refers to the shaft on a machine tool that drives the workpiece or cutting tool to rotate. It typically consists of a spindle core, bearings, and transmission components. To meet the high-efficiency requirements of machining large aluminum structural components for new energy vehicles, large gantry and horizontal five-axis CNC machine tools need to possess high speed and high cutting removal rates. Therefore, electric spindles are required to have high speed and high rigidity. Chinese patent ZL202120038547.6 discloses a floating tool release cylinder mechanism for the end of a spindle. It has a cylinder at the rear end of the spindle, with a piston inside. Hydraulic oil is supplied to the cylinder to drive the piston axially, pushing a pull rod to release the tool. During tool release, the axial force generated by the pull rod on the rotor is partially loaded onto the bearing assembly outside the rotor, adversely affecting the service life of the bearing assembly and requiring improvement. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a dual-piston spindle structure to reduce the axial force on the bearing assembly inside the spindle.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a double-piston spindle structure, wherein a rear piston is provided at the rear end of the spindle, a rotor is provided inside the spindle, a pull rod is inserted inside the rotor, the rear piston is used to push the pull rod toward the front end of the spindle, an annular rotor disc is provided on the outer wall of the rotor, the rotor disc is located at the front end of the spindle, and an axially movable front piston ring is provided on the side of the rotor disc facing away from the rear piston, the front piston ring is used to apply an axial reaction force to the rotor disc from the front end of the spindle toward the rear end of the spindle.

[0005] The spindle wall is provided with a first oil passage and a second oil passage. The first oil passage is used to introduce hydraulic oil for driving the rear piston, and the second oil passage is used to introduce hydraulic oil for driving the front piston ring. The first oil passage and the second oil passage are connected by a branch channel that can be opened and closed. When the branch channel is open, the rear piston and the front piston ring are driven synchronously by hydraulic oil. When the branch channel is closed, the first oil passage and the second oil passage are independent of each other.

[0006] The inner wall of the branch channel is provided with internal threads. When a plugging screw is screwed into the branch channel, the branch channel is in a closed state.

[0007] The rear end of the spindle is also provided with a rear cover. The first oil passage, the second oil passage and the branch channel are located in the wall of the rear cover. The wall of the rear cover is also provided with a through hole coaxial with the branch channel. The through hole and the branch channel are respectively located on both sides of the second oil passage. The inner wall of the through hole is provided with an internal thread for threaded connection with the plugging screw.

[0008] The rear cover is provided with a first inlet connected to the first oil passage, and the rear cover is also provided with a second inlet connected to the second oil passage; when the branch passage is in the connected state, the first inlet or the second inlet is closed.

[0009] The rear end of the spindle is also equipped with a hydraulic cylinder and a cylinder cover. The rear piston is located inside the hydraulic cylinder, and the cylinder cover is fitted over the opening of the hydraulic cylinder. The hydraulic cylinder is fixed to the middle of the outer side of the rear cover. The first oil passage extends from the rear cover to the hydraulic cylinder and the cylinder cover in sequence. The outlet of the first oil passage is located in the cylinder cover and faces the end face of the rear piston away from the connecting rod.

[0010] A sensor disc is fixedly fitted on the upper part of the pull rod, and the lower end of the rear piston pushes the pull rod through the sensor disc; a proximity switch is radially inserted into the wall of the rear cover, and the proximity switch is used to detect whether the sensor disc is in position.

[0011] The front end of the main shaft is equipped with a front bearing housing, a dustproof ring, and a ring spray plate. The dustproof ring is fixed to the end face of the front bearing housing. The rotor passes through the front bearing housing and the dustproof ring. The ring spray plate is located between the dustproof ring and the rotor. The front piston ring is surrounded by the rotor fly disc, the dustproof ring, and the ring spray plate.

[0012] The second oil passage extends sequentially to the front bearing housing, dust ring, and ring spray plate. The opening of the second oil passage is located on the ring spray plate and faces the end face of the front piston ring away from the rotor fly disk.

[0013] The dustproof ring has several receiving cylinders evenly distributed around the central axis of the front piston ring on the stepped surface facing the front piston ring. A return spring is installed in the receiving cylinder, and the outer end of the return spring abuts against the front piston ring.

[0014] The main shaft wall is also provided with an air intake passage for compressed gas. The air intake passage extends to the front bearing housing and dust ring. The front piston ring is provided with a transfer passage. The rotor is provided with an exhaust passage. The outlet of the exhaust passage is located on the outer end face of the rotor. When the front piston ring is in contact with the rotor disc, the transfer passage connects the air intake passage and the exhaust passage.

[0015] The beneficial effects of this invention compared with the prior art are as follows: by setting a front piston ring at the front end of the spindle to apply an axial reaction force to the rotor fly disk pointing towards the rear end of the spindle, when the tool is released, the axial force generated on the rotor when the rear piston pushes the pull rod is directed towards the front end of the spindle. The axial reaction force is opposite to the axial force, so the bearing assembly inside the spindle will not bear the axial force, and the service life of the bearing assembly is improved.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of the present invention more obvious and understandable, preferred embodiments are described in detail below. Attached Figure Description

[0017] Figure 1 This is a perspective view of the main axis of the present invention.

[0018] Figure 2 for Figure 1 Enlarged view of region A.

[0019] Figure 3 This is a sectional view of the main axis of the present invention.

[0020] Figure 4 This is a partial sectional view of the front end of the spindle of the present invention.

[0021] Figure 5 This is a sectional view of the main axis of the present invention.

[0022] Figure 6 for Figure 5 Enlarged view of region B.

[0023] Figure 7 This is a sectional view of the rear end of the spindle of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] 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.

[0026] This invention relates to a dual-piston spindle structure, the specific structure of which is as follows: Figure 1-7 As shown.

[0027] In some embodiments, such as Figure 1 As shown, a rear piston 41 capable of axial movement is provided at the rear end of the spindle 10. A rotor 20 is located inside the spindle 10, and a drawbar 30 passes through the rotor 20. The rear piston 41 is used to push the drawbar 30 towards the front end of the spindle 10 to release the tool. Figure 1 As shown, an annular rotor disc 21 is provided on the outer wall of the rotor 20, and the rotor disc 21 is located at the front end of the main shaft 10. A front piston ring 51 with axial movement is provided on the side of the rotor disc 21 facing away from the rear piston 41. The front piston ring 51 is used to apply pressure to the rotor disc 21 from the front end of the main shaft 10 to the rear end of the main shaft 10. Figure 1 Axial reaction force in the direction X.

[0028] In some embodiments, such as Figure 2As shown, the main shaft 10 has a first oil passage 111 and a second oil passage 112 in its wall. The first oil passage 111 is used to supply hydraulic oil for driving the rear piston 41, and the second oil passage 112 is used to supply hydraulic oil for driving the front piston ring 51. Figure 2 As shown, the first oil passage 111 and the second oil passage 112 are connected by a closable branch channel 113. The branch channel 113 can be opened or closed as needed. Specifically, the inner wall of the branch channel 113 has internal threads. When a plugging screw (not shown) is screwed into the branch channel 113, the branch channel 113 is closed, and the first oil passage 111 and the second oil passage 112 are independent. When no plugging screw is screwed into the branch channel 113, the branch channel 113 is open, and the rear piston 41 and the front piston ring 51 are synchronously driven by hydraulic oil.

[0029] In addition, such as Figure 2 As shown, a rear cover 11 is also provided at the rear end of the main shaft 10. The first oil passage 111, the second oil passage 112, and the branch channel 113 are all located within the wall of the rear cover 11. The wall of the rear cover 11 is also provided with a through hole 114 coaxial with the branch channel 113. The opening of the through hole 114 is located on the outer surface of the rear cover 11, and the through hole 114 and the branch channel 113 are respectively located on both sides of the second oil passage 112. Moreover, the inner wall of the through hole 114 is provided with an internal thread for threaded connection with the plugging screw. Therefore, when the plugging screw is screwed into the through hole 114 and the branch channel 113, the branch channel 113 can be closed and the through hole 114 can be closed at the same time, preventing hydraulic oil from leaking out from the through hole 114. When it is not necessary to close the branch channel 113, the plugging screw can be screwed into the through hole 114 without screwing it into the branch channel 113. Alternatively, two plugging screws, one long and one short, can be installed. The shorter plugging screw can only be screwed into the through hole 114, allowing the branch channel 113 to be connected; while the longer plugging screw can be screwed into both the through hole 114 and the branch channel 113, thus sealing the branch channel 113.

[0030] In addition, such as Figure 2 As shown, the rear cover 11 is provided with a first inlet 114 communicating with the first oil passage 111 and a second inlet 115 communicating with the second oil passage 112. When the branch passage 113 is in the connected state, the first inlet 114 or the second inlet 115 is closed, and hydraulic oil can be introduced and pressure applied to the hydraulic oil using only one of them.

[0031] In addition, such as Figure 2As shown, the rear end of the main shaft 10 is also equipped with a hydraulic cylinder 42 and a cylinder head 43. The rear piston 41 is located inside the hydraulic cylinder 42, and the cylinder head 43 covers the opening of the hydraulic cylinder 42. The hydraulic cylinder 42 is fixed to the middle of the outer side of the rear cover 11. The first oil passage 111 extends sequentially from the rear cover 11 to the hydraulic cylinder 42 and the cylinder head 43. The outlet 1111 of the first oil passage 111 is located in the cylinder head 43 and faces the end face 411 of the rear piston 41 away from the pull rod 30. Therefore, when hydraulic oil is introduced into the first oil passage 111, the hydraulic oil enters the hydraulic cylinder 42, which can push the rear piston 41 to move towards the pull rod.

[0032] In some embodiments, such as Figure 3 As shown, the front end of the main shaft 10 is provided with a front bearing housing 52, a dustproof ring 53, and a ring spray plate 54. The dustproof ring 53 is fixed to the end face of the front bearing housing 52. The rotor 20 passes through the front bearing housing 52 and the dustproof ring 53. The ring spray plate 54 is located between the dustproof ring 53 and the rotor 20. The front piston ring 51 is surrounded by the rotor fly disk 21, the dustproof ring 53, and the ring spray plate 54. The second oil passage 112 of the rear cover 11 passes through the wall of the steel cylinder 13 of the main shaft 10 and then extends sequentially to the front bearing housing 52, the dustproof ring 53, and the ring spray plate 54. The opening 1121 of the second oil passage 112 is located on the ring spray plate 54 and faces the end face 510 of the front piston ring 51 away from the rotor fly disk 21. Therefore, when hydraulic oil is introduced into the second oil passage 112, the hydraulic oil can eventually push the front piston ring 51 towards the rotor fly disk 21. When the piston ring 51 moves to contact with the rotor disc 21, the stepped surface 519 of the front piston ring 51 also contacts the stepped surface 531 of the dust ring 53. Therefore, the front piston ring 51 will stop moving. When the tie rod 30 generates an axial force on the rotor 20, due to the obstruction of the front piston ring 51, the front piston ring 51 generates an axial reaction force on the rotor 20, and the rotor 20 will not move axially.

[0033] When a tool change is required, if the branch channel 113 is connected, the hydraulic oil in the first oil passage 111 and the second oil passage 112 will be under force simultaneously. Therefore, the hydraulic oil will simultaneously push the rear piston 41 and the front piston ring 51 to move. The hydraulic oil pushes the rear piston 41, and the rear piston 41 pushes the tie rod 30 to move axially. The tie rod 30 will generate an axial force on the rotor 20. Meanwhile, the hydraulic oil pushes the front piston ring 51 to move towards the rotor fly disk 21 until the front piston ring 51 is in contact with the rotor fly disk 21. The front piston ring 51 generates an axial reaction force on the rotor fly disk 21. Under the action of the axial force and the axial reaction force, the rotor 20 will not move axially, so no axial force will be applied to the bearing assembly.

[0034] Alternatively, if the branch channel 113 is closed, the first oil passage 111 and the second oil passage 112 are independent of each other. When a tool change is required, the hydraulic oil in the second oil passage 112 can be controlled to push the front piston ring 51 to move towards the rotor fly disk 21 until it is close to the rotor fly disk 21. Then, the hydraulic oil in the first oil passage 111 can be controlled to drive the rear piston 41 to push the pull rod 30 to move axially to release the tool. Due to the obstruction of the front piston ring 51, the axial force generated by the pull rod 30 on the rotor 20 cannot make the rotor 20 move axially. Therefore, the rotor 20 will not apply axial force to the bearing assembly.

[0035] In some embodiments, such as Figure 4 As shown, the dustproof ring 53 has several receiving cylinders 532 evenly distributed around the central axis of the front piston ring 51 on the stepped surface 531 facing the front piston ring 51. A return spring 55 is installed in each receiving cylinder 532, with its outer end abutting against the front piston ring 51. When the cutting is released, the pressure applied to the hydraulic oil is removed, and the return spring 55 pushes the front piston ring 51 back to its original position, preventing the front piston ring 51 from contacting the rotor fly disk 21 and causing friction.

[0036] In some embodiments, such as Figure 5 , 6 As shown, the spindle 10 also has an air intake duct 14 for compressed gas in its wall. The air intake duct 14 extends to the front bearing housing 52 and the dust ring 53, and the outlet 141 of the air intake duct 14 is located in the annular groove 533 at the inner corner of the stepped surface 531 of the dust ring 53. The front piston ring 51 has a V-shaped transfer air passage 511, and the rotor 20 has an exhaust passage 201, with the outlet 202 of the exhaust passage 201 located on the outer end face of the rotor 20. When the front piston ring 51 moves to fit against the rotor disc 21, the two ends of the transfer air passage 511 are connected to the air intake duct 14 and the exhaust passage 201, respectively. The compressed gas in the air intake duct 14 will enter the exhaust passage 201 through the transfer air passage 511 and finally be discharged from the outlet 202 of the exhaust passage 201, so as to clean the end face of the rotor 20 by blowing air when the tool holder 90 is separated from the end face of the rotor 20 during the tool release process. Sealing rings 512 are sandwiched between the two adjacent vertical surfaces of the stepped surface 531 of the dustproof ring 53 and the front piston ring 51. Therefore, when the front piston ring 51 moves to fit against the rotor disc 21, there will be no air leakage when entering the intermediate air passage 511 from the intake passage 14. Furthermore, when the front piston ring 51 is pressed against the rotor disc 21, there will be no air leakage when entering the exhaust passage 201 from the intermediate air passage 511. Thus, utilizing the axially movable characteristic of the front piston ring 51, when air blowing is required for cleaning after knife loosening, the front piston ring 51 moves to fit against the rotor disc 21. The front piston ring 51 both holds the rotor 20 and ensures the air passage is connected while preventing compressed gas leakage.

[0037] like Figure 7As shown, a sensor disk 35 is fixedly sleeved on the upper part of the pull rod 30, and the lower end of the rear piston 41 pushes the pull rod 30 through the sensor disk 35. A proximity switch 16 is radially inserted into the wall of the rear cover 11. The proximity switch 16 is used to detect whether the sensor disk 35 is in position: if the sensor disk 35 is detected to be in position, it indicates that the pull rod 30 is in position during the tool tightening process; if the sensor disk 35 is not detected, it indicates that the tool loosening process is in progress. By setting a radial proximity switch 16 on the rear cover 11 to detect the sensor disk 35, the axial dimension of the entire spindle can be effectively reduced.

[0038] This invention applies an axial reaction force to the rotor disc 21 pointing towards the rear end of the spindle 10 by setting a front piston ring 51 at the front end of the spindle 10. When the tool is released, the axial force generated on the rotor 20 by the rear piston 41 pushing the pull rod 30 is directed towards the front end of the spindle 10. The axial reaction force is opposite to the axial force. Under the action of the axial reaction force and the axial force, the rotor 20 will not move axially. The bearing assembly inside the spindle 10 will not bear the axial force, and the service life of the bearing assembly is improved.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0041] The above examples are merely illustrative of the technical content of the present invention to facilitate easier understanding by the reader, but do not imply that the implementation of the present invention is limited to these examples. Any technical extensions or re-creations made based on the present invention are protected by the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A dual-piston spindle structure, wherein a rear piston is provided at the rear end of the spindle, a rotor is provided inside the spindle, a pull rod is inserted inside the rotor, and the rear piston is used to push the pull rod toward the front end of the spindle, characterized in that, The outer wall of the rotor is provided with an annular rotor disc, which is located at the front end of the main shaft. A front piston ring with axial movement is provided on the side of the rotor disc facing away from the rear piston. The front piston ring applies an axial reaction force to the rotor disc from the front end of the main shaft to the rear end. The wall of the main shaft is provided with a first oil passage and a second oil passage. The first oil passage is used to supply hydraulic oil for driving the rear piston, and the second oil passage is used to supply hydraulic oil for driving the front piston ring. The first and second oil passages are connected by a closable branch channel. When the branch channel is open, the rear piston and the front piston ring are driven synchronously by hydraulic oil. When the branch channel is closed, the first and second oil passages are independent of each other. The front end of the main shaft is provided with a front bearing housing, a dustproof ring and a ring spray plate. The dustproof ring is fixed to the end face of the front bearing housing. The rotor passes through the front bearing housing and the dustproof ring. The ring spray plate is located between the dustproof ring and the rotor. The front piston ring is surrounded by the rotor fly disc, the dustproof ring and the ring spray plate. The main shaft wall is also provided with an air intake passage for compressed gas, which extends to the front bearing housing and dustproof ring. The air intake passage outlet is located in the annular groove at the inner corner of the dustproof ring step surface. The front piston ring is provided with a V-shaped transfer passage, and an exhaust passage is provided in the rotor. The exhaust passage outlet is located on the outer end face of the rotor. When the front piston ring moves to fit against the rotor disc, the two ends of the transfer passage are connected to the air intake passage and the exhaust passage, respectively.

2. The dual-piston spindle structure as described in claim 1, characterized in that, The inner wall of the branch channel is provided with internal threads. When a plugging screw is screwed into the branch channel, the branch channel is in a closed state.

3. The dual-piston spindle structure as described in claim 2, characterized in that, The rear end of the main shaft is also provided with a rear cover. The first oil passage, the second oil passage and the branch channel are located in the wall of the rear cover. The wall of the rear cover is also provided with a through hole coaxial with the branch channel. The through hole and the branch channel are respectively located on both sides of the second oil passage. The inner wall of the through hole is provided with an internal thread for threaded connection with the plugging screw.

4. The dual-piston spindle structure as described in claim 3, characterized in that, The rear cover is provided with a first inlet communicating with the first oil passage, and the rear cover is also provided with a second inlet communicating with the second oil passage; when the branch passage is in a connected state, the first inlet or the second inlet is closed.

5. The dual-piston spindle structure as described in claim 3, characterized in that, The rear end of the main shaft is also provided with a hydraulic cylinder and a cylinder cover. The rear piston is located inside the hydraulic cylinder. The cylinder cover covers the opening of the hydraulic cylinder. The hydraulic cylinder is fixed to the middle of the outer side of the rear cover. The first oil passage extends from the rear cover to the hydraulic cylinder and the cylinder cover in sequence. The outlet of the first oil passage is located in the cylinder cover and faces the end face of the rear piston away from the pull rod.

6. The dual-piston spindle structure as described in claim 3, characterized in that, A sensor disk is fixedly sleeved on the upper part of the pull rod, and the lower end of the rear piston pushes the pull rod through the sensor disk; a proximity switch is radially inserted into the wall of the rear cover, and the proximity switch is used to detect whether the sensor disk is in position.

7. The dual-piston spindle structure as described in claim 6, characterized in that, The second oil passage extends sequentially to the front bearing housing, the dust ring, and the ring spray plate. The opening of the second oil passage is located on the ring spray plate and faces the end face of the front piston ring away from the rotor fly disk.

8. The dual-piston spindle structure as described in claim 6, characterized in that, The dustproof ring has several receiving cylinders evenly distributed around the central axis of the front piston ring on the stepped surface facing the front piston ring. A return spring is provided in the receiving cylinder, and the outer end of the return spring abuts against the front piston ring.

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