Split type direct drive spindle assembly

Abstract

This invention relates to the field of CNC machine tool technology, specifically to a split-type direct-drive spindle assembly, including a spindle housing. The spindle housing has front and rear bearing holes at both ends, with a front bearing assembly and a rear bearing assembly installed in each hole. A spindle is fixedly connected to the adjacent ends of the front and rear bearing assemblies. A motor housing is located on one side of the spindle housing, with a stator fixedly connected to its inner circumference. By placing the motor housing on one side of the spindle housing and integrally forming the rotary cylinder with its flange, an independent drive unit is created. This allows the motor unit to be completely removed from the spindle housing. Repairing or replacing the motor does not require disassembling the front and rear bearing assemblies and the spindle inside the spindle housing, significantly reducing maintenance difficulty and cost.

Description

Technical Field

[0001] This invention relates to the field of CNC machine tool technology, specifically to a split-type direct-drive spindle assembly. Background Technology

[0002] The spindle assembly of a CNC machine tool is its core component, directly affecting machining accuracy and efficiency. Traditional CNC machine tool spindle assemblies mainly come in two forms: One type is the modular electric spindle, which integrates the motor stator and rotor (7), bearings, etc., into a single unit. The entire modular spindle is then installed by boring holes in the spindle housing. Although this structure is easy to install, the motor stator is installed inside the unit housing, so if the motor is damaged, the entire unit needs to be replaced, resulting in high maintenance costs. Furthermore, the modular structure has difficulty in heat dissipation and is prone to thermal deformation. The spindle unit and the spindle housing have a clearance fit, resulting in poor spindle rigidity.

[0003] Another type is the box-type electric spindle, in which the motor stator is directly integrated into the spindle box and the rotor (7) is directly mounted on the spindle. Although this structure is compact, the motor stator is directly embedded in the spindle box, making the casting and processing of the box difficult. If the motor fails, the entire spindle box needs to be disassembled, which is extremely inconvenient for maintenance. At the same time, the rotary cylinder is mostly placed externally at the tail of the spindle, resulting in a long axial dimension.

[0004] In addition, the traditional structure also has the following common problems: First, the encoder is not protected enough and is easily corroded by cutting fluid and dust, which leads to signal distortion or damage; Second, the connection between the rotor (7) and the spindle is mostly keyed or interference fit. Keyed connection has a fit clearance that affects accuracy, while interference fit is difficult to disassemble; Third, the cooling system is not perfect and the bearing thermal deformation affects accuracy. Summary of the Invention

[0005] The purpose of this invention is to provide a split-type direct-drive spindle assembly to solve the problems mentioned in the prior art as described in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A split-type direct-drive spindle assembly includes a spindle housing. A front bearing hole and a rear bearing hole are respectively provided at both ends of the spindle housing. A front bearing assembly and a rear bearing assembly are respectively installed in the front bearing hole and the rear bearing hole. A spindle is fixedly connected to the adjacent ends of the front bearing assembly and the rear bearing assembly. A motor housing is provided on one side of the spindle housing. A stator is fixedly connected to the inner circumference of the motor housing, and a rotor is rotatably connected inside the motor housing. A hydraulic cylinder flange is integrally formed at one end of the rotor. A rotary hydraulic cylinder is fixedly connected to one end of the hydraulic cylinder flange, and the piston end of the rotary hydraulic cylinder is fixedly connected to the rear bearing assembly.

[0007] Furthermore, a tapered journal is installed at one end of the rear bearing assembly, and the tapered journal and the rotary cylinder are fixedly connected by a tapered sleeve.

[0008] Furthermore, an encoder cover is fixedly connected to one end of the motor housing, an encoder is fixedly connected to one end of the encoder cover, and the encoder is fixedly connected to one end of the cylinder flange.

[0009] Furthermore, one end of the cylinder flange is fixedly connected to multiple protrusions, and one end of the encoder cover is provided with multiple grooves, which are respectively inserted and engaged with the multiple protrusions.

[0010] Furthermore, the gap between the plurality of protrusions and the plurality of grooves is 0.3 mm.

[0011] Furthermore, the motor housing and the spindle box are fixedly connected by a connecting flange.

[0012] Furthermore, the spindle housing is made of high-strength cast iron HT300.

[0013] Furthermore, a stainless steel spiral tube is pre-embedded inside the conical sleeve, and both ends of the stainless steel spiral tube are connected and communicated with the external coolant.

[0014] Furthermore, the inner circumferential walls of the front bearing hole and the rear bearing hole of the spindle housing are provided with water channels, which are connected to the external coolant.

[0015] Furthermore, the tapered sleeve is a tensioning sleeve.

[0016] The technical solution provided by this invention has the following advantages compared with the known prior art: 1. By placing the motor housing on one side of the spindle housing and integrally molding the rotary cylinder with the cylinder flange to form an independent drive unit, the motor unit can be completely disassembled from the spindle housing. When repairing or replacing the motor, it is not necessary to disassemble the front bearing assembly, rear bearing assembly and spindle inside the spindle housing, which greatly reduces the difficulty and cost of maintenance.

[0017] Second, by setting a tapered sleeve between the tapered journal at one end of the rear bearing assembly and the rotary cylinder for fixed connection, the fit clearance of traditional key connections or interference fits is eliminated, realizing clearance-free torque transmission and ensuring high centering accuracy of the spindle and drive part; at the same time, the tapered sleeve connection method is easy to disassemble, solving the problem of difficult disassembly of interference fits. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 This is a first front perspective view of the present invention; Figure 2 This is a perspective view of the main cross-section of the present invention; Figure 3 For the present invention Figure 2 A magnified view of a section at point A in the middle; Figure 4 This is a top perspective view of the present invention; Figure 5 This is a bottom-view perspective view of the present invention; Figure 6 This is a second front perspective view of the present invention.

[0020] In the diagram: 1. Spindle housing; 2. Motor housing; 3. Hydraulic cylinder flange; 4. Connecting flange; 5. Spindle; 6. Stator; 7. Rotor; 8. Rotary hydraulic cylinder; 9. Tapered sleeve; 10. Encoder cover; 11. Encoder; 12. Protrusion; 13. Groove. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] The present invention will be further described below with reference to embodiments.

[0023] Example: A split-type direct-drive spindle assembly, such as Figures 1-6 As shown, the device includes a spindle housing 1. A front bearing hole and a rear bearing hole are respectively provided at both ends of the spindle housing 1. A front bearing assembly and a rear bearing assembly are respectively installed in the front bearing hole and the rear bearing hole. A spindle 5 is fixedly connected to the adjacent ends of the front bearing assembly and the rear bearing assembly. A motor housing 2 is provided on one side of the spindle housing 1. A stator 6 is fixedly connected to the inner circumference of the motor housing 2, and a rotor 7 is rotatably connected inside the motor housing 2. A hydraulic cylinder flange 3 is integrally formed at one end of the rotor 7. A rotary hydraulic cylinder 8 is fixedly connected to one end of the hydraulic cylinder flange 3. The piston end of the rotary hydraulic cylinder 8 is fixedly connected to the rear bearing assembly.

[0024] In a specific embodiment of the present invention, the spindle housing 1 serves as the supporting foundation for the entire assembly. Front bearing holes and rear bearing holes are respectively provided at both ends for precise installation of the front and rear bearing assemblies. The front and rear bearing assemblies jointly support the spindle 5, enabling it to rotate at high speed and withstand cutting loads. The motor housing 2 is independently disposed on one side of the spindle housing 1, and a stator 6 is fixed to its inner circumference. The stator 6 generates a rotating magnetic field when energized. A rotary cylinder 8 is rotatably connected inside the motor housing 2. One end of the rotary cylinder 8 has an integrally formed cylinder flange 3, which is used to partially integrate the rotary cylinder 8 with the rotor 7. The piston end of the rotary cylinder 8 is fixedly connected to the rear bearing assembly, and its function is to control the clamping and loosening of the front clamp, such as a chuck, via a pull rod. This embodiment integrates the rotary cylinder 8 and the rotor 7 into one unit, eliminating the coupling in the traditional structure and shortening the axial dimension.

[0025] Please refer to the details. Figure 1-6 A tapered journal is installed at one end of the rear bearing assembly, and the tapered journal and the rotary cylinder 8 are fixedly connected by a tapered sleeve 9. An encoder cover 10 is fixedly connected to one end of the motor housing 2, and an encoder 11 is fixedly connected to one end of the encoder cover 10. The encoder 11 is fixedly connected to one end of the cylinder flange 3.

[0026] In this embodiment, a tapered journal is installed at one end of the rear bearing assembly, and this tapered journal is fixedly connected to the rotary cylinder 8 via a tapered sleeve 9. The function of the tapered sleeve 9 is that when axially locked, the tapered sleeve 9 expands radially, transmitting the rotational power of the rotary cylinder 8 to the tapered journal at the rear end of the main shaft 5 without clearance. Compared with traditional key connections, the tapered sleeve 9 eliminates the fit clearance, improving centering accuracy and the smoothness of torque transmission; compared with interference fits, the tapered sleeve 9 is easy to disassemble and maintain. An encoder cover 10 is fixedly connected to one end of the motor housing 2, forming a closed protective space. An encoder 11 is fixedly connected to one end of the encoder cover 10, and the encoder 11 is also fixedly connected to one end of the hydraulic cylinder flange 3. Thus, the rotating part of the encoder 11, the rotor 7, rotates synchronously with the hydraulic cylinder flange 3, while the fixed part of the encoder 11, the reading head, is indirectly fixed to the motor housing 2 through the encoder cover 10. The encoder 11 detects the position and speed of the rotor 7 in real time and feeds the signal back to the control system, achieving precise speed control and position positioning.

[0027] Please refer to the details. Figure 1-6 One end of the cylinder flange 3 is fixedly connected with multiple protrusions 12, and one end of the encoder cover 10 is provided with multiple grooves 13, which are respectively inserted and engaged with the multiple protrusions 12. The gap between the multiple protrusions 12 and the multiple grooves 13 is 0.3 mm.

[0028] Please refer to the details. Figure 1-6 The motor housing 2 and the spindle box 1 are fixedly connected by a connecting flange 4; The spindle housing 1 is made of high-strength cast iron HT300; A stainless steel spiral tube is pre-embedded inside the cone sleeve 9. Both ends of the stainless steel spiral tube are connected to and communicate with the external coolant. Water channels are provided on the inner circumference of the front bearing hole and the rear bearing hole of the spindle housing 1, and the water channels are connected to the external coolant. Tapered sleeve 9 is an expansion sleeve.

[0029] In this embodiment, a plurality of protrusions 12 are fixedly connected to one end of the cylinder flange 3, and a plurality of grooves 13 are provided at one end of the encoder cover 10. The grooves 13 are respectively engaged with the protrusions 12. This structure of the protrusions 12 and grooves 13 interlocking forms a labyrinth seal. Its function is to prevent external cutting fluid and dust from entering the area where the encoder 11 is located by using a tortuous gap path without generating contact friction, thus ensuring smooth rotation and achieving reliable protection. The gap between the multiple protrusions 12 and the multiple grooves 13 is 0.3mm. The purpose of this gap is twofold: if the gap is too large, the sealing effect will decrease, and fine dust will easily enter; if the gap is too small, contact friction may occur due to thermal expansion or machining errors. A gap of 0.3mm ensures non-contact, frictionless rotation while providing sufficient fluid resistance, effectively preventing the intrusion of cutting fluid and dust. This is a proven optimal value. The motor housing 2 and the spindle housing 1 are fixedly connected by a connecting flange 4. The function of the connecting flange 4 is twofold: firstly, to provide a reliable mechanical connection, ensuring the motor unit is securely mounted on the spindle housing 1; secondly, the locating stop on the flange ensures the coaxiality of the inner bore axis of the motor housing 2 with the axis of the spindle 5 inside the spindle housing 1, thereby ensuring a uniform air gap between the stator 6 and the rotor 7 and preventing stator rubbing. Simultaneously, the flange connection facilitates the overall assembly and disassembly of the motor unit. The spindle housing 1 is made of high-strength cast iron HT300. The purpose of this material is that HT300 has a high tensile strength (≥300MPa) and good damping properties. Using this material to cast the spindle housing 1 effectively absorbs vibrations generated during cutting while maintaining sufficient static stiffness to ensure the positional accuracy of the spindle 5 under heavy cutting. Furthermore, cast iron has good wear resistance and dimensional stability, and is not easily deformed during long-term use. A stainless steel spiral tube is pre-embedded within the cone sleeve 9, with both ends connected to and communicating with the external coolant. It should be noted that in actual manufacturing, the stainless steel spiral tube is pre-embedded in the mounting base of the cone sleeve 9. The purpose of this structure is that when the coolant flows through the stainless steel spiral tube, the spiral flow path significantly increases the heat exchange path and heat exchange area, effectively removing heat generated near the cone sleeve 9 and the motor stator 6. Simultaneously, the pre-embedded casting process ensures a seamless connection between the spiral tube and the base, eliminating the need for plugs and joints, thus completely eliminating the risk of coolant leakage. The inner circumferential walls of the front and rear bearing bores of the spindle housing 1 are provided with water channels that connect to the external coolant. These water channels are integrally formed during casting and surround the mounting positions of the front and rear bearing assemblies. Their function is as follows: when the spindle 5 rotates at high speed, the friction between the rolling elements and raceways inside the bearings generates a large amount of heat. The coolant flows through these water channels, directly cooling the bearing bore walls, thereby carrying away the heat generated by the bearings and preventing excessive bearing temperature rise that could lead to thermal deformation that could be transferred to the spindle 5, thus maintaining the geometric accuracy of the spindle 5. Independent or series-connected water channel designs can distribute the flow rate according to the difference in heat generation between the front and rear bearings, achieving temperature balance. Tapered sleeve 9 is a tensioning sleeve. A tensioning sleeve is a standardized mechanical connecting element, typically composed of an inner ring, an outer ring, and a locking screw. Its working principle is as follows: by tightening the axial bolt, the inner and outer tapered rings move axially relative to each other, generating radial expansion force. This, in turn, clamps the journal at the rear end of the spindle 5 and the connecting journal of the rotary cylinder 8 with a constant and uniform pressure. The tensioning sleeve enables a gapless, high-rigidity connection and can transmit large torques, making it suitable for heavy cutting conditions. Furthermore, during disassembly, simply loosening the bolts allows the tensioning sleeve to automatically reset, preventing damage to the journal surface and facilitating repeated disassembly and maintenance.

[0030] Working Principle: The spindle housing 1 serves as the supporting foundation for the entire assembly. Front and rear bearing holes are respectively provided at both ends for precise installation of the front and rear bearing assemblies. The front and rear bearing assemblies jointly support the spindle 5, enabling it to rotate at high speed and withstand cutting loads. The motor housing 2 is independently located on one side of the spindle housing 1, with a stator 6 fixed to its inner circumference. The stator 6 generates a rotating magnetic field when energized. A rotary cylinder 8 is rotatably connected inside the motor housing 2. One end of the rotary cylinder 8 has an integrally formed cylinder flange 3, which integrates the rotary cylinder 8 with the rotor 7. The piston end of the rotary cylinder 8 is fixedly connected to the rear bearing assembly, and its function is to control the clamping and loosening of the front clamp, such as a chuck, via a pull rod. This embodiment integrates the rotary cylinder 8 and the rotor 7 into one unit, eliminating the coupling in the traditional structure and shortening the axial dimension.

[0031] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A split-type direct-drive spindle assembly, comprising a spindle housing (1), characterized in that: The spindle housing (1) has a front bearing hole and a rear bearing hole at both ends. A front bearing assembly and a rear bearing assembly are installed in the front bearing hole and the rear bearing hole, respectively. A spindle (5) is fixedly connected to the near end of the front bearing assembly and the rear bearing assembly. A motor housing (2) is provided on one side of the spindle housing (1). A stator (6) is fixedly connected to the inner circumference of the motor housing (2). A rotor (7) is rotatably connected inside the motor housing (2). A cylinder flange (3) is integrally formed at one end of the rotor (7). A rotary cylinder (8) is fixedly connected to one end of the cylinder flange (3). The piston end of the rotary cylinder (8) is fixedly connected to the rear bearing assembly.

2. The split-type direct-drive spindle assembly according to claim 1, characterized in that: A tapered journal is installed at one end of the rear bearing assembly, and the tapered journal and the rotary cylinder (8) are fixedly connected by a tapered sleeve (9).

3. A split-type direct-drive spindle assembly according to claim 2, characterized in that: An encoder cover (10) is fixedly connected to one end of the motor housing (2), and an encoder (11) is fixedly connected to one end of the encoder cover (10). The encoder (11) is fixedly connected to one end of the cylinder flange (3).

4. A split-type direct-drive spindle assembly according to claim 3, characterized in that: One end of the cylinder flange (3) is fixedly connected to a plurality of protrusions (12), and one end of the encoder cover (10) is provided with a plurality of grooves (13), and the plurality of grooves (13) are respectively inserted into and cooperate with the plurality of protrusions (12).

5. A split-type direct-drive spindle assembly according to claim 4, characterized in that: The gap between the plurality of protrusions (12) and the plurality of grooves (13) is 0.3 mm.

6. A split-type direct-drive spindle assembly according to claim 5, characterized in that: The motor housing (2) and the spindle box (1) are fixedly connected by a connecting flange (4).

7. A split-type direct-drive spindle assembly according to claim 6, characterized in that: The spindle housing (1) is made of high-strength cast iron HT300.

8. A split-type direct-drive spindle assembly according to claim 7, characterized in that: The conical sleeve (9) is pre-cast with a stainless steel spiral tube, and both ends of the stainless steel spiral tube are connected to and communicate with the external coolant.

9. A split-type direct-drive spindle assembly according to claim 8, characterized in that: The inner circumferential walls of the front bearing hole and the rear bearing hole of the spindle housing (1) are provided with water channels, which are connected to external coolant.

10. A split-type direct-drive spindle assembly according to claim 9, characterized in that: The tapered sleeve (9) is a tensioning sleeve.

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