A B-axis swing head for a vertical machining center

Abstract

The present invention discloses a B-axis swing head for a vertical machining center, comprising a spindle box, a spindle, a front bearing assembly, a brake assembly, a torque motor unit, a rear bearing assembly and a drag chain unit, wherein the front end of the spindle is fixed on the spindle box, the drag chain unit is fixed on the rear end of the spindle, the front bearing assembly and the brake assembly are respectively sleeved on the front end of the spindle, the rear bearing assembly is sleeved on the rear end of the spindle, the torque motor unit comprises a first torque motor and a second torque motor for providing driving force to the spindle, the first torque motor and the second torque motor are arranged in series between the front bearing assembly and the rear bearing assembly, and the first torque motor and the second torque motor are respectively sleeved on the spindle. The B-axis swing head has a compact structure, can provide sufficient torsional force and high dynamic characteristics to the spindle in an energized state, improves the rotation speed and machining efficiency of the spindle, and can make the radial size of the entire B-axis swing head more compact, and can be applied to occasions with strict requirements on motor diameter and space.

Description

Technical Field

[0001] The invention relates to a numerical control machine tool accessory, in particular to a B-axis swing head for a vertical machining center. Background Art

[0002] The B-axis swing head for vertical machining center is a common high-end CNC machine tool accessory. It can form a vertical five-axis linkage machining center with a turntable. The drive mode of the B-axis swing head on the market is mainly mechanical, generally using a worm gear or rack and pinion drive. The B-axis speed of the swing head is generally not high and the dynamic characteristics are poor. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a B-axis swing head for a vertical machining center with a compact structure and high dynamic characteristics in view of the deficiencies in the prior art.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a B-axis swing head for a vertical machining center, comprising a spindle box, a spindle, a front bearing assembly, a brake assembly, a torque motor unit, a rear bearing assembly and a drag chain unit, the front end of the spindle is fixed on the spindle box, the drag chain unit is fixed on the rear end of the spindle, the front bearing assembly and the brake assembly are respectively sleeved on the front end of the spindle, the rear bearing assembly is sleeved on the rear end of the spindle, the torque motor unit comprises a first torque motor and a second torque motor for providing driving force to the spindle, the first torque motor and the second torque motor are arranged in series between the front bearing assembly and the rear bearing assembly, and the first torque motor and the second torque motor are respectively sleeved on the spindle.

[0005] The B-axis swing head for the vertical machining center of the present invention adopts a dual-torque motor series drive structure composed of a first torque motor and a second torque motor to drive the spindle. The structure is compact and can provide sufficient torsional force and high dynamic characteristics to the spindle when powered on, thereby improving the spindle speed and machining efficiency. At the same time, the radial size of the entire B-axis swing head can be made more compact, and can be used in occasions with strict requirements on motor diameter and space.

[0006] Preferably, the first torque motor comprises a first motor stator, a first rotor connecting disk and a first motor rotor, the second torque motor comprises a second motor stator, a second rotor connecting disk and a second motor rotor, a stator sleeve is fixed between the front bearing assembly and the rear bearing assembly, the first motor stator and the second motor stator are respectively fixed in the stator sleeve by front and rear interference fit, the first rotor connecting disk is sleeved and fixed on the main shaft by screws, the first motor rotor is centered with the first rotor connecting disk and fixedly connected by screws, the second rotor connecting disk is sleeved and fixed on the main shaft by screws, and the second motor rotor is centered with the second rotor connecting disk and fixedly connected by screws.

[0007] Preferably, the front bearing assembly comprises a YRT bearing, a front bearing seat, a front bearing pressure ring and a front bearing pressure cover, the YRT bearing is installed in the front bearing seat, the front bearing seat is centered with the stator sleeve and is fixedly connected by screws, a stop is provided at one end of the spindle box, the stop is centered with the inner ring of the YRT bearing, the front bearing pressure ring is sleeved on the stop and axially presses the inner ring of the YRT bearing, the front bearing pressure ring and the inner ring of the YRT bearing are fixed to the spindle box by screws, the outer circle of the front bearing pressure cover and the outer ring of the YRT bearing are centered with the front bearing seat respectively, the front bearing pressure cover axially presses the outer ring of the YRT bearing to the front bearing seat, the front end of the spindle is fixed to the spindle box by screws, and the outer circle of the front end of the spindle is centered with the spindle box; the rear bearing assembly comprises a cross roller bearing, a rear bearing seat, a spacer and a rear bearing pressure cover, The crossed roller bearing is installed in the rear bearing seat, the rear bearing seat is centered with the stator sleeve and fixedly connected by screws, the inner ring of the crossed roller bearing is centered with the main shaft, the front end and rear end of the inner ring of the crossed roller bearing are respectively limited and pressed by the spacer and an encoder seat, the front end face of the spacer is fitted with the second rotor connecting disk, the encoder seat is threadedly connected and fixed on the main shaft, a dust cover is provided on the rear side of the encoder seat, the dust cover is installed at the rear end of the rear bearing seat and sleeved on the main shaft, the front end and rear end of the outer ring of the crossed roller bearing are respectively limited and pressed by the rear bearing seat and the rear bearing pressure cover, the rear bearing pressure cover is fixed to the rear bearing seat by screws, the front end face of the first motor stator is fitted with the stator sleeve, the rear end face of the first motor stator is fitted with the front end face of the second motor stator, and the rear end face of the second motor stator is fitted with the rear bearing seat.

[0008] Preferably, the brake assembly comprises a piston, a cylinder barrel, a cylinder cover, an inner brake pad and an outer brake pad, the cylinder cover is fixed to the front bearing seat by screws, the cylinder barrel is fixed to the front end of the cylinder cover by screws, the outer circle of the piston is centeringly matched with the front bearing seat, the piston is located at the front side of the cylinder cover and at the outside of the cylinder barrel, the piston can move forward and backward, the piston, cylinder barrel and cylinder cover form a loosening oil chamber, a loosening oil passage communicating with the loosening oil chamber is provided in the stator sleeve, the cylinder cover and the cylinder barrel, the piston and the cylinder cover form a clamping oil chamber, a clamping oil passage communicating with the clamping oil chamber is provided in the stator sleeve and the cylinder cover, the inner brake pad is fixed to the main shaft, the outer brake pad is fixed to the front bearing seat, the front end face of the inner brake pad faces the front bearing seat, the rear end face of the inner brake pad faces the front end face of the outer brake pad, and the rear end face of the outer brake pad faces the front end face of the piston. The above-mentioned brake assembly adopts a hydraulic brake structure, and realizes smooth braking of the B-axis swing head through the fitting and deformation of the inner brake pad and the outer brake pad. The force that forces the inner brake pad and the outer brake pad to deform comes from the force of the hydraulic oil on the piston. Under the action of the hydraulic oil, the piston can move forward and backward. When the inner brake pad and the outer brake pad are deformed, the front end face of the inner brake pad contacts the front bearing seat, and the rear end face of the inner brake pad contacts the front end face of the outer brake pad, forming a double friction surface. The design of the double friction surface can provide double locking torque under the condition of limited volume of the B-axis swing head, realize hydraulic braking with high locking force, and can ensure the rigidity and precision of fixed-angle processing of the vertical machining center.

[0009] Preferably, the radially inner front end and rear end of the inner brake pad are respectively pressed by a labyrinth ring and an inner pressure cover, the labyrinth ring centering sleeve is arranged on the main shaft, the front end face of the labyrinth ring is fitted with the main shaft, the labyrinth ring, the inner brake pad and the inner pressure cover are fixed to the main shaft by screws, the radially outer front end face of the outer brake pad is fitted with the front bearing seat, the radially outer rear end face of the outer brake pad is fitted with an outer pressure cover, and the outer brake pad and the outer pressure cover are both fixed to the front bearing seat by screws.

[0010] Preferably, the release oil circuit includes a first oil circuit, a second oil circuit and a third oil circuit which are connected in sequence, the first oil circuit is opened in the stator sleeve, the second oil circuit is opened in the oil cylinder head, the third oil circuit is opened in the oil cylinder barrel, and the third oil circuit is connected to the release oil chamber; the clamping oil circuit includes a fourth oil circuit and a fifth oil circuit which are connected, the fourth oil circuit is opened in the stator sleeve, the fifth oil circuit is opened in the oil cylinder head, and the fifth oil circuit is connected to the clamping oil chamber. During braking, the hydraulic oil of the brake oil circuit reaches the clamping oil chamber through the fourth oil circuit and the fifth oil circuit, the piston moves forward, squeezes the outer brake pad, causes the outer brake pad to deform elastically and makes the outer brake pad fit with the inner brake pad, that is, forms a friction surface; the piston moves forward further, presses the outer brake pad and the inner brake pad to continuously deform, until the inner brake pad fits with the front bearing seat, that is, forms another friction surface, and realizes the clamping action. When releasing, the hydraulic oil in the release oil circuit flows through the first oil circuit, the second oil circuit and the third oil circuit to reach the release oil chamber. At this time, the piston moves backward and separates from the outer brake pad. Finally, the inner brake pad separates from the outer brake pad to achieve the release action.

[0011] Preferably, a piston seal is provided between the outer circle of the piston and the front bearing seat, a tie rod seal and a bidirectional piston seal are provided between the inner circle of the piston and the oil cylinder barrel, a first O-ring is provided between the oil cylinder cover and the front bearing seat, a second O-ring and a third O-ring are provided between the oil cylinder cover and the oil cylinder barrel, and the third O-ring is located outside the entrance of the third oil circuit. The combination of the piston seal, the bidirectional piston seal, the first O-ring and the second O-ring can ensure the sealing of the clamping oil chamber; the combination of the bidirectional piston seal and the tie rod seal can ensure the sealing of the loosening oil chamber.

[0012] As a preferred embodiment, a ring groove is provided on one side of the spindle box near the front bearing seat, the ring groove is coaxially arranged with the spindle, an axial labyrinth structure is provided at the junction of the front end of the front bearing seat and the spindle box, a V-shaped seal is provided at the rear side of the axial labyrinth structure, the V-shaped seal sleeve is provided on the spindle box, a fourth O-shaped seal ring is provided between the outer circle of the front bearing gland and the front bearing seat, a fifth O-shaped seal ring is provided between the spindle box and the inner circle of the front bearing gland, the V-shaped seal ring and the fifth O-shaped seal ring are arranged front and rear on the front side of the stopper, and a sixth O-shaped seal ring is provided on the side of the front bearing seat connected to the machine tool. The ring groove can accumulate part of the cooling water and iron filings, so that part of the cooling water and iron filings flow down along the circumference of the spindle box to achieve the first level of sealing; the axial labyrinth structure can further block part of the cooling water and iron filings, and the remaining cooling water and iron filings are blocked by the V-shaped seal to achieve the second level of sealing; the fourth O-shaped seal ring and the fifth O-shaped seal ring play a further blocking role to achieve a complete sealing effect. In addition, the sixth O-ring can ensure the sealing of the torque motor unit.

[0013] Preferably, a dustproof ring is provided between the dustproof cover and the main shaft, and a seventh O-type sealing ring is provided between the rear bearing seat and the dustproof cover. The dustproof cover, the dustproof ring and the seventh O-type sealing ring can ensure the sealing of the rear end of the swing head.

[0014] Preferably, the drag chain unit comprises a transition plate, a wire drum, a pipeline, a drag chain, a drag chain bracket, a drag chain cover plate and a pipeline fixing plate, the transition plate is fixed to the rear end of the spindle by screws, the wire drum is fixed to the rear end of the transition plate by screws, the drag chain bracket is fixed to the rear end of the wire drum by screws, the drag chain is wrapped around the drag chain bracket, one end of the drag chain is fixed to the drag chain bracket by screws, and the other end of the drag chain is fixed to the pipeline fixing plate, the drag chain cover plate and the pipeline fixing plate are respectively mounted on the drag chain bracket, and the drag chain cover plate is mounted on the side of the drag chain bracket close to the machine tool, the spindle, transition plate, wire drum and drag chain bracket are all hollow cylinders with conductive ends, the front end of the pipeline is fixed to the spindle box, and the rear end of the pipeline successively passes through the inner holes of the spindle, transition plate, wire drum and drag chain bracket to enter one end of the drag chain, and passes out from the other end of the drag chain, and is finally fixed to the pipeline fixing plate. The difficulty of routing the pipes and cables inside the swing head is how to prevent the twisting and rupture of the pipes due to the rotation of the spindle box. To solve this problem, the internal pipe routing of this swing head adopts a drag chain, which converts the rotation of the pipeline in space into the rotation of the drag chain around the B axis, that is, the rise and fall of the drooping part of the drag chain, thereby effectively protecting the safety of the pipeline. In this swing head, the drag chain cover plays a protective role; the pipeline refers to the collection of hydraulic pipes, air pipes, power lines and other pipelines that pass through the inside of the swing head. During the processing of the vertical machining center, the pipeline rotates around the B axis with the spindle box and the spindle.

[0015] Compared with the prior art, the present invention has the following advantages: the B-axis swing head for the vertical machining center of the present invention adopts a dual torque motor series drive structure consisting of a first torque motor and a second torque motor to drive the spindle, which has a compact structure and can provide sufficient torsional force and high dynamic characteristics to the spindle when powered on, thereby improving the spindle speed and machining efficiency, and at the same time can make the radial size of the entire B-axis swing head more compact, and can be used in occasions with strict requirements on motor diameter and space. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the B-axis swing head in the embodiment;

[0017] Figure 2 for Figure 1 Enlarged view of point A in the middle (in Figure 1 On the basis of adding sealing structures such as piston seals);

[0018] Figure 3 for Figure 1 Enlarged view of point B (in Figure 1 A fourth O-ring and other sealing structures are added on the basis of

[0019] Figure 4 for Figure 1 Enlarged view of C in the middle (in Figure 1 A seventh O-ring is added on the basis of

[0020] Figure 5 It is a rear side view of the B-axis swing head in the embodiment. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to the accompanying drawings.

[0022] The B-axis swing head for the vertical machining center of Example 1, as shown in the figure, includes a spindle box 1, a spindle 2, a front bearing assembly, a brake assembly, a torque motor unit, a rear bearing assembly and a drag chain unit. The front end of the spindle 2 is fixed on the spindle box 1, the drag chain unit is fixed to the rear end of the spindle 2, the front bearing assembly and the brake assembly are respectively sleeved on the front end of the spindle 2, and the rear bearing assembly is sleeved on the rear end of the spindle 2. The torque motor unit includes a first torque motor and a second torque motor for providing driving force to the spindle 2. The first torque motor and the second torque motor are arranged in series between the front bearing assembly and the rear bearing assembly, and the first torque motor and the second torque motor are respectively sleeved on the spindle 2.

[0023] In Example 1, the first torque motor includes a first motor stator 31, a first rotor connecting disk 32 and a first motor rotor 33, and the second torque motor includes a second motor stator 41, a second rotor connecting disk 42 and a second motor rotor 43. A stator sleeve 5 is fixed between the front bearing assembly and the rear bearing assembly. The first motor stator 31 and the second motor stator 41 are respectively fixed in the stator sleeve 5 by front and rear interference fit. The first rotor connecting disk 32 is sleeved and fixed on the main shaft 2 by screws. The first motor rotor 33 is centered with the first rotor connecting disk 32 and fixedly connected by screws. The second rotor connecting disk 42 is sleeved and fixed on the main shaft 2 by screws. The second motor rotor 43 is centered with the second rotor connecting disk 42 and fixedly connected by screws.

[0024] In Example 1, the front bearing assembly includes a YRT bearing, a front bearing seat 63, a front bearing pressure ring 64 and a front bearing cover 65. The YRT bearing is installed in the front bearing seat 63. The front bearing seat 63 is centered with the stator sleeve 5 and is fixedly connected by screws. A stopper 11 is provided at one end of the spindle box 1. The stopper 11 is centered with the inner ring 61 of the YRT bearing. The front bearing pressure ring 64 is sleeved on the stopper 11 and axially presses the inner ring 61 of the YRT bearing. The front bearing pressure ring 64 and the YRT bearing are fixedly connected. The inner ring 61 of the T bearing is fixed to the spindle box 1 by screws, the outer circle of the front bearing cover 65 and the outer ring 62 of the YRT bearing are respectively matched with the front bearing seat 63 for centering, and the front bearing cover 65 axially presses and fixes the outer ring 62 of the YRT bearing on the front bearing seat 63. The front end of the spindle 2 is fixed to the spindle box 1 by screws, and the outer circle of the front end of the spindle 2 is matched with the spindle box 1 for centering; the rear bearing assembly includes a cross roller bearing 71, a rear bearing seat 72, a spacer 73 and a rear bearing cover 74, the cross roller bearing 71 is installed in the rear bearing seat 72, the rear bearing seat 72 is centered with the stator sleeve 5 and fixedly connected by screws, the inner ring of the cross roller bearing 71 is centered with the main shaft 2, the front end and the rear end of the inner ring of the cross roller bearing 71 are respectively limited and pressed by the spacer sleeve 73 and an encoder seat 75, the front end surface of the spacer sleeve 73 is fitted with the second rotor connecting plate 42, the encoder seat 75 is threadedly connected and fixed on the main shaft 2, and a dust cover 7 is provided on the rear side of the encoder seat 75 6. The dust cover 76 is installed at the rear end of the rear bearing seat 72 and sleeved on the main shaft 2. The front end and rear end of the outer ring of the cross roller bearing 71 are respectively limited and pressed by the rear bearing seat 72 and the rear bearing cover 74. The rear bearing cover 74 is fixed to the rear bearing seat 72 by screws. The front end face of the first motor stator 31 fits with the stator sleeve 5, the rear end face of the first motor stator 31 fits with the front end face of the second motor stator 41, and the rear end face of the second motor stator 41 fits with the rear bearing seat 72.

[0025] In Example 1, the brake assembly includes a piston 81, a cylinder barrel 82, a cylinder cover 83, an inner brake pad 84 and an outer brake pad 85. The cylinder cover 83 is fixed to the front bearing seat 63 by screws, and the cylinder barrel 82 is fixed to the front end of the cylinder cover 83 by screws. The outer circle of the piston 81 is centered with the front bearing seat 63. The piston 81 is located at the front side of the cylinder cover 83 and at the outer side of the cylinder barrel 82. The piston 81 can move forward and backward. The piston 81, the cylinder barrel 82 and the cylinder cover 83 surround a loose oil chamber 86. The stator sleeve 5, the oil A loosening oil circuit communicating with the loosening oil chamber 86 is provided in the cylinder head 83 and the cylinder barrel 82, the piston 81 and the cylinder head 83 form a clamping oil chamber 87, a clamping oil circuit communicating with the clamping oil chamber 87 is provided in the stator sleeve 5 and the cylinder head 83, the inner brake pad 84 is fixed on the main shaft 2, the outer brake pad 85 is fixed on the front bearing seat 63, the front end face of the inner brake pad 84 faces the front bearing seat 63, the rear end face of the inner brake pad 84 faces the front end face of the outer brake pad 85, and the rear end face of the outer brake pad 85 faces the front end face of the piston 81. The front and rear ends of the radial inner side of the inner brake pad 84 are respectively pressed by a labyrinth ring 88 and an inner pressure cover 89. The labyrinth ring 88 is centeringly sleeved on the main shaft 2. The front end face of the labyrinth ring 88 fits with the main shaft 2. The labyrinth ring 88, the inner brake pad 84 and the inner pressure cover 89 are fixed to the main shaft 2 by screws. The front end face of the radial outer side of the outer brake pad 85 fits with the front bearing seat 63. The rear end face of the radial outer side of the outer brake pad 85 fits with an outer pressure cover 80. The outer brake pad 85 and the outer pressure cover 80 are fixed to the front bearing seat 63 by screws. The loosening oil circuit includes a first oil circuit 51, a second oil circuit 52 and a third oil circuit 53 which are connected in sequence. The first oil circuit 51 is opened in the stator sleeve 5, the second oil circuit 52 is opened in the cylinder cover 83, the third oil circuit 53 is opened in the cylinder barrel 82, and the third oil circuit 53 is connected to the loosening oil chamber 86; the clamping oil circuit includes a fourth oil circuit 54 and a fifth oil circuit 55 which are connected. The fourth oil circuit 54 is opened in the stator sleeve 5, the fifth oil circuit 55 is opened in the cylinder cover 83, and the fifth oil circuit 55 is connected to the clamping oil chamber 87. A piston seal 91 is arranged between the outer circle of the piston 81 and the front bearing seat 63, a tie rod seal and a bidirectional piston seal 92 are arranged front and back between the inner circle of the piston 81 and the cylinder barrel 82, a first O-ring 93 is arranged between the cylinder cover 83 and the front bearing seat 63, a second O-ring 94 and a third O-ring 95 are arranged front and back between the cylinder cover 83 and the cylinder barrel 82, and the third O-ring 95 is located on the outside of the entrance of the third oil circuit 53.

[0026] The B-axis swing head for a vertical machining center of Example 2 differs from Example 1 in that, in Example 2, a ring groove 12 is provided on a side of the spindle box 1 close to the front bearing seat 63, and the ring groove 12 is coaxially arranged with the spindle 2. An axial labyrinth structure 13 is provided at the junction between the front end of the front bearing seat 63 and the spindle box 1, and a V-shaped seal 14 is provided on the rear side of the axial labyrinth structure 13. The V-shaped seal 14 is sleeved on the spindle box 1, and a fourth O-ring 96 is provided between the outer circle of the front bearing cover 65 and the front bearing seat 63, and a fifth O-ring 97 is provided between the spindle box 1 and the inner circle of the front bearing cover 65. The V-shaped seal 14 and the fifth O-ring 97 are arranged front and rear on the front side of the stop 11, and a sixth O-ring 98 is provided on the side of the front bearing seat 63 connected to the machine tool; a dust ring 77 is provided between the dust cover 76 and the spindle 2, and a seventh O-ring 99 is provided between the rear bearing seat 72 and the dust cover 76.

[0027] The B-axis swing head for a vertical machining center of Example 3 is different from Example 2 in that, in Example 3, the drag chain unit includes a transition plate 101, a cable drum 102, a pipeline 103, a drag chain 104, a drag chain bracket 105, a drag chain cover 106 and a pipeline fixing plate 107, the transition plate 101 is fixed to the rear end of the spindle 2 by screws, the cable drum 102 is fixed to the rear end of the transition plate 101 by screws, the drag chain bracket 105 is fixed to the rear end of the cable drum 102 by screws, the drag chain 104 is wrapped around the drag chain bracket 105, one end of the drag chain 104 is fixed to the drag chain bracket 105 by screws, and the other end of the drag chain 104 is fixed to the drag chain bracket 105 by screws. One end is fixed on the pipeline fixing plate 107, the drag chain cover 106 and the pipeline fixing plate 107 are respectively installed on the drag chain bracket 105, the drag chain cover 106 is installed on the side of the drag chain bracket 105 close to the machine tool, the spindle 2, the transition plate 101, the wiring drum 102 and the drag chain bracket 105 are all hollow cylinders with conductive ends, the front end of the pipeline 103 is fixed on the spindle box 1, and the rear end of the pipeline 103 successively passes through the inner holes of the spindle 2, the transition plate 101, the wiring drum 102 and the drag chain bracket 105 to enter one end of the drag chain 104, and passes through the other end of the drag chain 104, and is finally fixed on the pipeline fixing plate 107.

Claims

1. A B-axis swing head for a vertical machining center, characterized in that: It includes a spindle box, a spindle, a front bearing assembly, a brake assembly, a torque motor unit, a rear bearing assembly and a drag chain unit, the front end of the spindle is fixed on the spindle box, the drag chain unit is fixed on the rear end of the spindle, the front bearing assembly and the brake assembly are respectively sleeved on the front end of the spindle, the rear bearing assembly is sleeved on the rear end of the spindle, the torque motor unit includes a first torque motor and a second torque motor for providing driving force to the spindle, the first torque motor and the second torque motor are arranged in series between the front bearing assembly and the rear bearing assembly, and the first torque motor and the second torque motor are respectively sleeved on the spindle; The first torque motor comprises a first motor stator, a first rotor connecting plate and a first motor rotor, the second torque motor comprises a second motor stator, a second rotor connecting plate and a second motor rotor, a stator sleeve is fixed between the front bearing assembly and the rear bearing assembly, the first motor stator and the second motor stator are respectively fixed in the stator sleeve by front and rear interference fit, the first rotor connecting plate is sleeved and fixed on the main shaft by screws, the first motor rotor is centered with the first rotor connecting plate and fixedly connected by screws, the second rotor connecting plate is sleeved and fixed on the main shaft by screws, the second motor rotor is centered with the second rotor connecting plate and fixedly connected by screws; The front bearing assembly comprises a YRT bearing, a front bearing seat, a front bearing pressure ring and a front bearing pressure cover. The YRT bearing is installed in the front bearing seat. The front bearing seat is centered with the stator sleeve and fixedly connected by screws. A stop is provided at one end of the spindle box. The stop is centered with the inner ring of the YRT bearing. The front bearing pressure ring is sleeved on the stop and axially presses the inner ring of the YRT bearing. The front bearing pressure ring and the inner ring of the YRT bearing are fixed to the spindle box by screws. The outer circle of the front bearing pressure cover and the outer ring of the YRT bearing are centered with the front bearing seat respectively. The front bearing pressure cover axially presses and fixes the outer ring of the YRT bearing to the front bearing seat. The front end of the spindle is fixed to the spindle box by screws. The outer circle of the front end of the spindle is centered with the spindle box. The rear bearing assembly comprises a cross roller bearing, a rear bearing seat, a spacer and a rear bearing pressure cover. The cross roller bearing is installed in the rear bearing seat, the rear bearing seat is centered with the stator sleeve and fixedly connected by screws, the inner ring of the cross roller bearing is centered with the main shaft, the front end and rear end of the inner ring of the cross roller bearing are respectively limited and pressed by the spacer and an encoder seat, the front end face of the spacer is fitted with the second rotor connecting disk, the encoder seat is threadedly connected and fixed on the main shaft, a dust cover is provided on the rear side of the encoder seat, the dust cover is installed on the rear end of the rear bearing seat and sleeved on the main shaft, the front end and rear end of the outer ring of the cross roller bearing are respectively limited and pressed by the rear bearing seat and the rear bearing pressure cover, the rear bearing pressure cover is fixed to the rear bearing seat by screws, the front end face of the first motor stator is fitted with the stator sleeve, the rear end face of the first motor stator is fitted with the front end face of the second motor stator, and the rear end face of the second motor stator is fitted with the rear bearing seat; The brake assembly comprises a piston, a cylinder barrel, a cylinder cover, an inner brake pad and an outer brake pad. The cylinder cover is fixed to the front bearing seat by screws, and the cylinder barrel is fixed to the front end of the cylinder cover by screws. The outer circle of the piston is centered with the front bearing seat. The piston is located at the front side of the cylinder cover and at the outer side of the cylinder barrel. The piston can move forward and backward. The piston, cylinder barrel and cylinder cover form a loosening oil chamber. A loosening oil passage communicating with the loosening oil chamber is provided in the stator sleeve, the cylinder cover and the cylinder barrel. The piston and the cylinder cover form a clamping oil chamber. A clamping oil passage communicating with the clamping oil chamber is provided in the stator sleeve and the cylinder cover. The inner brake pad is fixed to the main shaft, and the outer brake pad is fixed to the front bearing seat. The front end face of the inner brake pad faces the front bearing seat, the rear end face of the inner brake pad faces the front end face of the outer brake pad, and the rear end face of the outer brake pad faces the front end face of the piston.

2. The B-axis swing head for a vertical machining center according to claim 1, characterized in that: The front end and rear end of the radial inner side of the inner brake pad are respectively pressed by a labyrinth ring and an inner pressure cover, the labyrinth ring centering sleeve is arranged on the main shaft, the front end face of the labyrinth ring is fitted with the main shaft, the labyrinth ring, the inner brake pad and the inner pressure cover are fixed to the main shaft by screws, the front end face of the radial outer side of the outer brake pad is fitted with the front bearing seat, the rear end face of the radial outer side of the outer brake pad is fitted with an outer pressure cover, and the outer brake pad and the outer pressure cover are fixed to the front bearing seat by screws.

3. The B-axis swing head for a vertical machining center according to claim 1, characterized in that: The loosening oil circuit includes a first oil circuit, a second oil circuit and a third oil circuit which are connected in sequence, the first oil circuit is opened in the stator sleeve, the second oil circuit is opened in the cylinder head, the third oil circuit is opened in the cylinder barrel, and the third oil circuit is connected to the loosening oil chamber; the clamping oil circuit includes a fourth oil circuit and a fifth oil circuit which are connected, the fourth oil circuit is opened in the stator sleeve, the fifth oil circuit is opened in the cylinder head, and the fifth oil circuit is connected to the clamping oil chamber.

4. The B-axis swing head for a vertical machining center according to claim 3, characterized in that: A piston seal is arranged between the outer circle of the piston and the front bearing seat, a tie rod seal and a bidirectional piston seal are arranged front and back between the inner circle of the piston and the cylinder barrel, a first O-ring is arranged between the cylinder cover and the front bearing seat, a second O-ring and a third O-ring are arranged front and back between the cylinder cover and the cylinder barrel, and the third O-ring is located on the outside of the entrance of the third oil circuit.

5. The B-axis swing head for a vertical machining center according to claim 1, characterized in that: A ring groove is provided on one side of the spindle box close to the front bearing seat, and the ring groove is coaxially arranged with the spindle. An axial labyrinth structure is provided at the junction of the front end of the front bearing seat and the spindle box, and a V-shaped seal is provided on the rear side of the axial labyrinth structure. The V-shaped seal sleeve is arranged on the spindle box, a fourth O-ring is provided between the outer circle of the front bearing cover and the front bearing seat, a fifth O-ring is provided between the spindle box and the inner circle of the front bearing cover, the V-shaped seal and the fifth O-ring are arranged front and back on the front side of the stop, and a sixth O-ring is provided on the side of the front bearing seat connected to the machine tool.

6. The B-axis swing head for a vertical machining center according to claim 5, characterized in that: A dustproof ring is arranged between the dustproof cover and the main shaft, and a seventh O-type sealing ring is arranged between the rear bearing seat and the dustproof cover.

7. The B-axis swing head for a vertical machining center according to claim 1, characterized in that: The drag chain unit comprises a transition plate, a wire drum, a pipeline, a drag chain, a drag chain bracket, a drag chain cover plate and a pipeline fixing plate, the transition plate is fixed to the rear end of the spindle by screws, the wire drum is fixed to the rear end of the transition plate by screws, the drag chain bracket is fixed to the rear end of the wire drum by screws, the drag chain is wrapped around the drag chain bracket, one end of the drag chain is fixed to the drag chain bracket by screws, and the other end of the drag chain is fixed to the pipeline fixing plate, the drag chain cover plate and the pipeline fixing plate are respectively installed on the drag chain bracket, and the drag chain cover plate is installed on the side of the drag chain bracket close to the machine tool, the spindle, transition plate, wire drum and drag chain bracket are all hollow cylinders with conductive ends, the front end of the pipeline is fixed to the spindle box, and the rear end of the pipeline successively passes through the inner holes of the spindle, transition plate, wire drum and drag chain bracket to enter one end of the drag chain, and passes out from the other end of the drag chain, and is finally fixed on the pipeline fixing plate.

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