Direct-driven static pressure headstock for high-precision grinding center

Abstract

The utility model discloses a direct-drive static pressure headstock for a high-precision grinding center, which relates to the field of grinding machines and comprises a shell, a headstock spindle, a rear end cover, a sealing component, a torque motor, an encoder, a total oil inlet hole and a total oil return hole. The headstock main shaft comprises a front shaft part and a rear shaft part which are installed in a shell, oil cavity conical surfaces are arranged at preset positions of the shell, the front shaft part and the rear shaft part, static pressure oil cavities are formed in the oil cavity conical surfaces, and the static pressure oil cavities are correspondingly communicated with branch oil inlet holes and branch oil return holes. The static pressure oil cavity is designed on the conical surface, so that radial and axial loads can be borne at the same time, and the complexity of a static pressure structure is reduced; by installing a high-precision encoder, the angle position of the headstock main shaft can be monitored in real time, the rotating speed of the motor can be accurately controlled in cooperation with a numerical control system and the like, and high-precision grinding of threaded workpieces and non-circular workpieces is achieved; meanwhile, the appearance size of the headstock is designed to be smaller, and the center height is lower, so that the headstock can be applied to a composite grinding center.

Description

Technical Field

[0001] The utility model relates to the field of grinding machines, in particular to a direct-drive hydrostatic headstock for a high-precision grinding center. Background Art

[0002] With the development of all walks of life, the parts used in various equipment and products are developing towards high precision and small volume. And with the increasingly fierce competition among enterprises, it is required that industrial machine tools have the advantages of high precision, high efficiency, small volume, long service life and good stability. For a compound grinding center, the headstock for driving the workpiece to rotate is a core component. Its rotational accuracy, positioning accuracy, service life and stability are crucial for the compound grinding center and directly affect the grinding accuracy of the workpiece.

[0003] The headstock is generally divided into a rolling bearing headstock and a hydrostatic bearing headstock. During the working process of the rolling bearing headstock, due to the rolling of the rolling elements in the bearing raceway, damage will inevitably occur, especially under heavy loads, and the damage will be aggravated after that, which will directly affect the accuracy and stability of the headstock. While in the hydrostatic bearing headstock, the headstock spindle and the bearing do not contact during operation and are separated by an oil film in the middle. Therefore, there is no wear. At the same time, due to the existence of the oil film, it has good shock absorption performance and good impact resistance performance.

[0004] The existing hydrostatic headstock is large in volume and high in center height, and cannot be applied to a compound grinding center. At the same time, the hydrostatic bearing has hydrostatic oil cavities in both the radial and axial directions, that is, a radial hydrostatic bearing and an axial hydrostatic bearing, which are respectively used to bear radial and axial loads. The structure is complex and the requirements for processing and assembly are relatively high. The existing hydrostatic headstock is not equipped with an encoder, and cannot monitor the current angular position of the headstock spindle, and cannot accurately control the rotation speed of the headstock spindle, and cannot be used for grinding threads and non-circular workpieces. Summary of the Utility Model

[0005] Purpose of the Utility Model: The utility model aims to provide a direct-drive hydrostatic headstock for a high-precision grinding center to solve the above problems existing in the prior art.

[0006] Technical Solution: A direct-drive hydrostatic headstock for a high-precision grinding center includes a housing, a headstock spindle, a rear end cover, a sealing assembly, a torque motor, an encoder, a total oil inlet hole and a total oil return hole;

[0007] Among them, the headstock spindle includes a front shaft portion and a rear shaft portion installed in the housing. Oil cavity cones are provided at predetermined positions on the housing, the front shaft portion, and the rear shaft portion. Static pressure oil cavities are formed within the oil cavity cones. A branch oil inlet hole and a branch oil return hole, which are opened at predetermined positions on the housing, communicate with the static pressure oil cavities correspondingly. The rear end cover is installed on the rear shaft portion and connected to the end of the housing. Sealing components are respectively installed at predetermined positions on the front shaft portion and the rear shaft portion for sealing. A torque motor is installed between the rear end cover and the rear shaft portion to drive the headstock spindle. An encoder is installed at a predetermined position on the rear shaft portion to monitor the position of the headstock spindle. A main oil inlet hole and a main oil return hole are respectively opened at predetermined positions on the housing. The main oil inlet hole communicates with the branch oil inlet hole for introducing pressurized hydraulic oil, and the main oil return hole communicates with the branch oil return hole for oil return.

[0008] In a further embodiment, the static pressure oil cavity includes a front shaft static pressure oil cavity and a rear shaft static pressure oil cavity;

[0009] Among them, the front shaft static pressure oil cavity is formed within the oil cavity cone between the front shaft portion and the housing, and the rear shaft static pressure oil cavity is formed within the oil cavity cone between the rear shaft portion and the housing. The front shaft static pressure oil cavity and the rear shaft static pressure oil cavity are used to cooperate with the oil cavity cone to form a static pressure oil film.

[0010] In a further embodiment, the branch oil inlet hole includes a front shaft oil cavity inlet hole and a rear shaft oil cavity inlet hole;

[0011] Among them, the front shaft oil cavity inlet hole is opened on the housing and communicates with the main oil inlet hole and the front shaft static pressure oil cavity, and the rear shaft oil cavity inlet hole is opened on the housing and communicates with the main oil inlet hole and the rear shaft static pressure oil cavity. The front shaft oil cavity inlet hole and the rear shaft oil cavity inlet hole are used to respectively introduce the hydraulic oil introduced into the main oil inlet hole into the front shaft static pressure oil cavity and the rear shaft static pressure oil cavity.

[0012] In a further embodiment, the branch oil return hole includes a front shaft return hole and a rear shaft return hole;

[0013] Among them, the front shaft return hole is opened on the housing and communicates with the front shaft static pressure oil cavity and the main oil return hole, and the rear shaft return hole is opened on the housing and communicates with the rear shaft static pressure oil cavity and the main oil return hole. The front shaft return hole and the rear shaft return hole are used to respectively divert the hydraulic oil flowing through the front shaft static pressure oil cavity and the rear shaft static pressure oil cavity to the main oil return hole for discharge.

[0014] In a further embodiment, the torque motor includes a stator and a rotor;

[0015] Among them, the stator is installed on the rear end cover, and the rotor is installed on the rear shaft portion.

[0016] In a further embodiment, the sealing assembly includes a front end cover and a front sealing ring;

[0017] Among them, the front end cover is installed at the connecting end of the housing and the front shaft portion, and the front sealing ring is installed between the front end cover and the front shaft portion for cooperating with the front end cover for sealing.

[0018] In a further embodiment, the sealing assembly further includes an intermediate sealing ring;

[0019] Among them, the intermediate sealing ring is installed between the rear end cover and the rear shaft portion for sealing.

[0020] In a further embodiment, the sealing assembly further includes a rear sealing ring;

[0021] Among them, the rear sealing ring is installed at a predetermined position on the rear shaft portion for sealing.

[0022] Beneficial effects: The present utility model discloses a direct-drive hydrostatic headstock for a high-precision grinding center. By designing the hydrostatic oil cavity on the conical surface, it can bear radial and axial loads simultaneously, reducing the complexity of the hydrostatic structure; by installing a high-precision encoder, the angular position of the headstock spindle can be monitored in real time, and the motor speed can be accurately controlled in cooperation with a numerical control system, etc., to achieve high-precision grinding of threaded workpieces and non-circular workpieces; at the same time, the headstock is designed with a smaller external dimension and a lower center height, making it applicable to a compound grinding center. Description of the Drawings

[0023] Figure 1 It is a schematic cross-sectional structure view of the present utility model.

[0024] Figure 2 It is a schematic oil circuit view of the present utility model.

[0025] Figure 3 It is an oil cavity structure view of the housing of the present utility model.

[0026] In the figures, the reference numerals of each drawing are: 1, housing; 2, front shaft portion; 3, rear shaft portion; 4, front end cover; 5, rear end cover; 6, torque motor; 601, stator; 602, rotor; 7, encoder; 8, front sealing ring; 9, intermediate sealing ring; 10, rear sealing ring; 11, total oil inlet hole; 12, front shaft oil cavity oil inlet hole; 13, rear shaft oil cavity oil inlet hole; 14, front shaft oil return hole; 15, rear shaft oil return hole; 16, front shaft hydrostatic oil cavity; 17, rear shaft hydrostatic oil cavity; 18, total oil return hole. Detailed Embodiments

[0027] In the following description, numerous specific details are given to provide a more thorough understanding of the present utility model. However, it will be apparent to those skilled in the art that the present utility model may be practiced without one or more of these details. In other instances, some well-known technical features are not described to avoid obscuring the present utility model.

[0028] The applicant believes that the existing hydrostatic headstock is relatively large in volume and has a relatively high center height, making it inapplicable to a compound grinding center; the existing hydrostatic bearings have hydrostatic oil cavities both radially and axially, namely a radial hydrostatic bearing and an axial hydrostatic bearing, which are respectively used to bear radial and axial loads, with a complex structure and relatively high requirements for machining and assembly; the existing hydrostatic headstock is not equipped with an encoder, unable to monitor the current angular position of the headstock spindle and accurately control the rotational speed of the headstock spindle, and thus cannot be used for grinding threads and non-circular workpieces.

[0029] Therefore, the applicant proposes a direct-drive hydrostatic headstock for a high-precision grinding center, as Figures 1 - 3 shown, which includes a housing 1, a headstock spindle, a rear end cover 5, a sealing assembly, a torque motor 6, and an encoder 7.

[0030] Among them, the headstock spindle includes a front shaft portion 2 and a rear shaft portion 3 installed in the housing 1. Oil cavity cones are provided at predetermined positions on the housing 1, the front shaft portion 2, and the rear shaft portion 3. Hydrostatic oil cavities are formed within the oil cavity cones. A branch oil inlet hole and a branch oil return hole are correspondingly communicated with the hydrostatic oil cavities and are opened at predetermined positions on the housing 1. A main oil inlet hole 11 and a main oil return hole 18 are also respectively opened at predetermined positions on the housing 1. The main oil inlet hole 11 is communicated with the branch oil inlet hole for introducing pressurized hydraulic oil, and the main oil return hole 18 is communicated with the branch oil return hole for oil return.

[0031] Specifically, the hydrostatic oil cavities include a front shaft hydrostatic oil cavity 16 and a rear shaft hydrostatic oil cavity 17. The branch oil inlet holes include a front shaft oil cavity inlet hole 12 and a rear shaft oil cavity inlet hole 13. The branch oil return holes include a front shaft oil return hole 14 and a rear shaft oil return hole 15.

[0032] Among them, the front axle static pressure oil cavity 16 is formed in the oil cavity conical surface between the front axle part 2 and the housing 1, and the rear axle static pressure oil cavity 17 is formed in the oil cavity conical surface between the rear axle part 3 and the housing 1. The front axle static pressure oil cavity 16 and the rear axle static pressure oil cavity 17 are used to cooperate with the oil cavity conical surface to form a static pressure oil film. The front axle oil cavity oil inlet hole 12 is opened on the housing 1 and is connected to the total oil inlet hole 11 and the front axle static pressure oil cavity 16. The rear axle oil cavity oil inlet hole 13 is opened on the housing 1 and is connected to the total oil inlet hole 11 and the rear axle static pressure oil cavity 17. The front axle oil cavity oil inlet hole 12 and the rear axle oil cavity oil inlet hole 13 are used to respectively introduce the hydraulic oil introduced into the total oil inlet hole 11 into the front axle static pressure oil cavity 16 and the rear axle static pressure oil cavity 17. The front axle oil return hole 14 is opened on the housing 1 and is connected to the front axle static pressure oil cavity 16 and the total oil return hole 18. The rear axle oil return hole 15 is opened on the housing 1 and is connected to the rear axle static pressure oil cavity 17 and the total oil return hole 18. The front axle oil return hole 14 and the rear axle oil return hole 15 are used to respectively divert the hydraulic oil flowing through the front axle static pressure oil cavity 16 and the rear axle static pressure oil cavity 17 to the total oil return hole 18 for export.

[0033] In this application, static pressure oil cavities are designed on the conical surfaces at both ends of the housing 1, and the static pressure bearings are designed to be integrated with the housing 1. Each static pressure oil cavity has an oil inlet hole for oil inlet. The front axle part 2 and the rear axle part 3 are installed on the housing 1, and the conical surfaces of the front axle part 2 and the rear axle part 3 are matched with the conical surface of the housing 1. Preferably, there are four static pressure oil cavities on the conical surfaces at both ends of the housing 1 in this application, and a static pressure oil film is formed on the conical surfaces of the front axle part 2 and the rear axle part 3. This oil film separates the housing 1 from the front axle part 2 and the rear axle part 3. Therefore, no wear occurs during the working process, and it has a long service life and high precision retention performance.

[0034] As Figures 1 - 2 shown, the rear end cover 5 is installed on the rear axle part 3 and is connected to the end of the housing 1. The sealing components are respectively installed at predetermined positions on the front axle part 2 and the rear axle part 3 for sealing. The torque motor 6 is installed between the rear end cover 5 and the rear axle part 3 for driving the headstock spindle. The encoder 7 is installed at a predetermined position on the rear axle part 3 for monitoring the position of the headstock spindle.

[0035] In this application, the sealing component includes a front end cover 4, a front sealing ring 8, an intermediate sealing ring 9, and a rear sealing ring 10.

[0036] Among them, the front end cover 4 is installed at the connecting end of the housing 1 and the front shaft portion 2. The front sealing ring 8 is installed between the front end cover 4 and the front shaft portion 2 for sealing in cooperation with the front end cover 4. The middle sealing ring 9 is installed between the rear end cover 5 and the rear shaft portion 3 for sealing. The rear sealing ring 10 is installed at a predetermined position on the rear shaft portion 3 for sealing. The front end cover 4 and the rear end cover 5 are installed on the housing 1 for sealing. The torque motor 6 is installed at the rear end of the headstock and functions to drive the main shaft of the headstock. The encoder 7 is installed on the rear shaft portion 3 and functions to monitor the angular position of the main shaft of the current headstock in real time. The front sealing ring 8 is installed on the front shaft portion 2, and the middle sealing ring 9 and the rear sealing ring 10 are installed on the rear shaft portion 3, which play a role in sealing, prevent hydraulic oil from leaking out, and prevent impurities and grinding fluid from invading the interior of the headstock.

[0037] In addition, the encoder 7 can monitor the current angular position of the main shaft of the headstock in real time, feedback the signal to the numerical control system, and the numerical control system issues instructions to control the rotation of the torque motor 6 to form a closed-loop control, which can accurately control the rotation speed of the main shaft of the headstock. This is very crucial when grinding threaded workpieces and non-circular workpieces. The torque motor 6 includes a stator 601 and a rotor 602. The stator 601 is installed on the rear end cover 5, and the rotor 602 is installed on the rear shaft portion 3.

[0038] During use, the pressurized hydraulic oil leads from the total oil inlet hole 11 of the housing 1 to the oil inlet holes of each oil cavity, thereby reaching the corresponding oil cavity, acting on the tapered surfaces of the front shaft portion 2 and the rear shaft portion 3 to form a static pressure oil film. Then the hydraulic oil flows from the static pressure oil cavity to the oil return hole and then returns to the oil tank. Since this oil film is generated on the tapered surface, it can bear bidirectional loads in the radial and axial directions, and the axial movement of the front shaft portion 2 and the rear shaft portion 3 is restricted by the self-positioning of the two tapered surfaces, without the need to be restricted by a thrust bearing, which simplifies the structure.

[0039] In this application, the external dimensions of the hydrostatic headstock are set to be smaller and the center height is lower, so that it can be applied to a compound grinding center; the hydrostatic bearing is designed to be integrated with the housing 1, and at the same time the hydrostatic oil cavity is designed on the tapered surface, which can bear bidirectional loads in the radial and axial directions without the need for a thrust hydrostatic bearing to restrict the axial movement of the main shaft of the headstock, reducing the complexity of the hydrostatic structure; at the same time, an encoder 7 is configured to monitor the angular position of the main shaft of the headstock in real time, and cooperate with the numerical control system and the motor to accurately control the motor speed, so that the hydrostatic headstock can be applied to grinding threaded workpieces and non-circular workpieces, expanding the application range of the hydrostatic headstock.

[0040] As above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation of the present invention itself. Various changes can be made in its form and details without departing from the spirit and scope of the present invention defined by the appended claims.

Claims

1. Direct drive hydrostatic headstock for high precision grinding center, characterized by: include: case; The headstock spindle comprises a front shaft portion and a rear shaft portion installed in the housing, the housing and the front shaft portion and the rear shaft portion are all provided with oil chamber conical surfaces at predetermined positions, a static oil chamber is formed in the oil chamber conical surface, and the static oil chamber is correspondingly connected with a branch oil inlet hole and a branch oil return hole opened at a predetermined position on the housing; A rear end cover, mounted on the rear axle portion and connected to the end of the housing; Sealing components, respectively installed at predetermined positions on the front axle portion and the rear axle portion, for sealing; A torque motor, installed between the rear end cover and the rear axle portion, for driving the headstock spindle; An encoder, mounted at a predetermined position on the rear axle portion, for monitoring the position of the headstock spindle; A total oil inlet hole and a total oil return hole are respectively opened at predetermined positions on the shell. The total oil inlet hole is connected with the branch oil inlet hole for introducing pressurized hydraulic oil, and the total oil return hole is connected with the branch oil return hole for returning oil.

2. The direct-drive static pressure headstock for a high-precision grinding center according to claim 1, characterized in that: The static pressure oil chamber includes a front axle static pressure oil chamber and a rear axle static pressure oil chamber; The front axle static pressure oil chamber is formed in the oil chamber conical surface between the front axle portion and the housing; The rear axle static pressure oil chamber is formed in the oil chamber conical surface between the rear axle portion and the housing; The front axle static pressure oil chamber and the rear axle static pressure oil chamber are used to cooperate with the oil chamber conical surface to form a static pressure oil film.

3. The direct-drive static pressure headstock for a high-precision grinding center according to claim 2, characterized in that: The branch oil inlet holes include a front axle oil chamber oil inlet hole and a rear axle oil chamber oil inlet hole; The front axle oil chamber oil inlet hole is opened on the housing and is connected with the main oil inlet hole and the front axle static pressure oil chamber; The rear axle oil chamber oil inlet hole is opened on the housing and is connected with the main oil inlet hole and the rear axle static pressure oil chamber; The front axle oil chamber oil inlet hole and the rear axle oil chamber oil inlet hole are used to introduce the hydraulic oil introduced into the main oil inlet hole into the front axle static pressure oil chamber and the rear axle static pressure oil chamber respectively.

4. The direct-drive static pressure headstock for a high-precision grinding center according to claim 2, characterized in that: The branch oil return holes include a front axle oil return hole and a rear axle oil return hole; The front axle oil return hole is opened on the housing and is connected with the front axle static pressure oil chamber and the total oil return hole; The rear axle oil return hole is opened on the housing and is connected with the rear axle static pressure oil chamber and the total oil return hole; The front axle oil return hole and the rear axle oil return hole are used to guide the hydraulic oil flowing through the front axle static pressure oil chamber and the rear axle static pressure oil chamber to the main oil return hole for output respectively.

5. The direct-drive static pressure headstock for a high-precision grinding center according to claim 1, characterized in that: The torque motor comprises a stator and a rotor; The stator is mounted on the rear end cover; The rotor is mounted on the rear axle portion.

6. The direct-drive static pressure headstock for a high-precision grinding center according to claim 1, characterized in that: The sealing assembly comprises a front end cover and a front sealing ring; The front end cover is mounted on the connecting end of the housing and the front shaft; The front sealing ring is installed between the front end cover and the front shaft portion, and is used to cooperate with the front end cover for sealing.

7. The direct-drive static pressure headstock for a high-precision grinding center according to claim 1, characterized in that: The sealing assembly also includes an intermediate sealing ring; The intermediate sealing ring is installed between the rear end cover and the rear axle portion for sealing.

8. The direct-drive static pressure headstock for a high-precision grinding center according to claim 1, characterized in that: The sealing assembly also includes a rear sealing ring; The rear sealing ring is installed at a predetermined position on the rear axle portion for sealing.

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