Direct-drive headstock for grinding precise non-circular and threaded workpieces

Abstract

The utility model discloses a direct-drive headstock for grinding precise non-circular and threaded workpieces, which relates to the field of grinding machines and comprises a headstock shell, a headstock spindle, a front end bearing, a rear end bearing, a torque motor, a high-precision encoder and a pneumatic clamp. And the headstock main shaft penetrates through the mounting cavity and is arranged in the headstock shell. By adopting the high-precision front end bearing and the high-precision rear end bearing which are specially used for the main shaft, the rotation precision of the headstock main shaft can be improved; closed-loop control is achieved through the encoder with the high-precision grating, and precise grinding of non-circular and threaded workpieces can be achieved through precise control over the rotating speed and position of the main shaft. The torque motor is arranged at the rear end of the main shaft, so that the bearing position structure at the front end is more compact, and the overall center height of the headstock is effectively reduced; by additionally arranging the pneumatic clamp structure, the grinding precision and safety of the precise non-circular and threaded workpieces can be improved.

Description

Technical Field

[0001] The utility model relates to the field of grinding machines, and particularly to a direct-drive headstock for grinding precision non-circular and threaded workpieces. Background Art

[0002] In order to make the overall structure of the traditional direct-drive headstock compact, the transmission part is usually simplified. The headstock spindle is directly driven by a torque motor, and the torque motor is installed between the front and rear bearings. At the same time, an encoder is installed on the headstock to accurately measure the rotation speed of the headstock and locate the current position of the headstock.

[0003] Due to the development of high-speed and ultra-high-speed grinding technologies, the pressure of the grinding fluid has also increased. Conventional seals can no longer meet the sealing requirements of the headstock. At the same time, as the core non-circular and threaded parts in industries such as new energy and robotics are increasingly developing towards high precision and small size, the center height of the conventional direct-drive headstock is relatively high, resulting in a waste of the center height and being unfavorable for cost control and lean production.

[0004] When the traditional direct-drive headstock is used to grind non-circular and threaded workpieces, in the case of an emergency power failure of the machine tool (such as an emergency power cut due to an accident during grinding or an overall power cut caused by the workshop power supply), since the motor enable signal disappears, the headstock spindle cannot be maintained at the current position. At this time, the grinding wheel will continue to rotate due to inertia, resulting in a reduction in the grinding quality of the workpiece or even scrapping of the workpiece. And when the non-circular and threaded workpiece has a large mass, only relying on the motor enable signal cannot stably maintain the headstock spindle at the predetermined position during tool setting, resulting in an error during tool setting and affecting the grinding accuracy of the workpiece. Summary of the Utility Model

[0005] Purpose of the utility model: The utility model aims to provide a direct-drive headstock for grinding precision non-circular and threaded workpieces to solve the above problems existing in the prior art.

[0006] Technical solution: A direct-drive headstock for grinding precision non-circular and threaded workpieces includes a headstock housing, a headstock spindle, a front-end bearing, a rear-end bearing, a torque motor, a high-precision encoder, and a pneumatic clamp;

[0007] Among them, a mounting cavity with a predetermined shape is provided inside the headstock housing. The headstock spindle passes through the mounting cavity and is arranged inside the headstock housing. A front bearing and a rear bearing are respectively arranged between the headstock spindle and the inner wall of the headstock housing, near the head and middle of the headstock spindle. Both the front bearing and the rear bearing adopt high-precision bearings to improve the rotational accuracy of the headstock spindle. A torque motor is installed between the headstock housing and the headstock spindle and is arranged near the tail of the headstock spindle to drive the headstock spindle to rotate. A high-precision encoder for controlling the rotational speed and position of the headstock spindle is arranged on one side of the torque motor away from the rear bearing. The pneumatic clamp includes a clamp body arranged between the torque motor and the rear bearing, a clamping jaw attached to the outer wall of the headstock spindle, and a spring cortex arranged inside the clamp body, connected to the clamping jaw and having a predetermined elastic force;

[0008] When the pneumatic clamp is in the locked state, the spring cortex in the pneumatic clamp generates an elastic force to clamp the headstock spindle by the clamping jaw;

[0009] When the pneumatic clamp is in the relaxed state, the inner air cavity of the spring cortex in the pneumatic clamp is filled with gas, and the spring cortex arches to disengage the clamping jaw from the headstock spindle.

[0010] In a further embodiment, a bearing end cover is installed at the connection between the headstock spindle and the head of the headstock housing. The bearing end cover abuts against the front bearing to seal the connection between the headstock spindle and the head of the headstock housing and limit the axial movement of the front bearing.

[0011] In a further embodiment, a sleeve is arranged between the front bearing and the rear bearing. The sleeve is sleeved outside the headstock spindle to limit the axial movement of the front bearing and the rear bearing.

[0012] In a further embodiment, a locking nut is arranged on the side of the rear bearing away from the front bearing. The locking nut is threadedly connected to the headstock spindle to limit the axial movement of the rear bearing and adjust the clearance of the rear bearing.

[0013] In a further embodiment, the stator of the torque motor is installed on the headstock housing, and the rotor of the torque motor is installed on the headstock spindle.

[0014] In a further embodiment, an opening and a closing port are also provided at a predetermined position on the pneumatic clamp;

[0015] In the initial state, the opening of the pneumatic clamp exhausts the gas in the inner air chamber of the spring cortex, and the closing port intakes air, so that the outer air chamber of the spring cortex is inflated and pressurized. At this time, the spring cortex is relaxed and stretched, so that the clamping jaw contacts and clamps with the headstock spindle;

[0016] When the headstock spindle needs to rotate, the opening of the pneumatic clamp intakes air, so that the inner air chamber of the spring cortex is inflated and pressurized, and the closing port exhausts the gas, so that the gas in the outer air chamber of the spring cortex is discharged. At this time, the spring cortex bends and arches, so that the clamping jaw is separated from the headstock spindle.

[0017] Beneficial effects: The present utility model discloses a direct drive headstock for grinding precision non-circular and threaded workpieces. By adopting high-precision front and rear bearings dedicated to the spindle, the rotational accuracy of the headstock spindle can be improved; by adopting an encoder with a high-precision grating to achieve closed-loop control, precise grinding of non-circular and threaded workpieces can be realized through precise control of the rotational speed and position of the spindle; by placing the torque motor at the rear end of the spindle, the bearing position structure at the front end can be made more compact, effectively reducing the overall center height of the headstock; by adding a pneumatic clamp structure, the grinding accuracy and safety of precision non-circular and threaded workpieces can be increased. Description of the Drawings

[0018] Figure 1 It is a schematic cross-sectional structure diagram of the present utility model.

[0019] Figure 2 It is a partial structure diagram of the pneumatic clamp of the present utility model.

[0020] Figure 3 It is a schematic diagram of the principle when the pneumatic clamp of the present utility model is locked.

[0021] Figure 4 It is a schematic diagram of the principle when the pneumatic clamp of the present utility model is relaxed.

[0022] Each reference numeral in the figure is: 1. Headstock housing; 2. Headstock spindle; 3. Front bearing; 4. Rear bearing; 5. Bearing end cover; 6. Sleeve; 7. Locking nut; 8. Torque motor; 9. High-precision encoder; 10. Pneumatic clamp; 11. Spring cortex; 12. Clamping jaw. Detailed Embodiments

[0023] In the following description, a large number of specific details are given to provide a more thorough understanding of the present utility model. However, it is obvious to those skilled in the art that the present utility model can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present utility model, some well-known technical features in the art are not described.

[0024] The applicant believes that in order to make the overall structure of the existing direct-drive headstock compact, the torque motor is usually directly installed between the front and rear bearings. Although this simplifies the transmission part, it will result in a relatively high center height of the direct-drive headstock, which not only causes waste of the center height but also is not conducive to cost control and lean production. At the same time, the headstock spindle of the existing direct-drive headstock also lacks an emergency clamping and unclamping function. When an emergency power failure occurs in the machine tool, the grinding wheel will continue to drive the spindle to rotate due to inertia, which will not only reduce the grinding quality of the workpiece but even cause the scrapping of the workpiece. And when the non-circular and threaded workpieces are relatively heavy, only relying on the motor cannot keep the headstock spindle stable at the predetermined position, and it is easy to generate errors during tool setting, thus affecting the grinding accuracy of the workpiece, etc.

[0025] Therefore, the applicant proposes a direct-drive headstock for grinding precision non-circular and threaded workpieces, as Figures 1 - 2 shown, which includes a headstock housing 1, a headstock spindle 2, a front bearing 3, a rear bearing 4, a bearing end cover 5, a bushing 6, a locking nut 7, a torque motor 8, a high-precision encoder 9, and a pneumatic clamp 10.

[0026] Specifically, as Figure 1 shown, a mounting cavity with a predetermined shape is provided inside the headstock housing 1 for mounting components such as the headstock spindle 2. At the same time, in order to achieve the purpose of reducing the center height, the mounting surface of the machine tool worktable is designed at the front end of the headstock housing 1.

[0027] As Figure 1 shown, the headstock spindle 2 passes through the mounting cavity and is arranged inside the headstock housing 1. The front bearing 3 and the rear bearing 4 are arranged between the headstock spindle 2 and the inner wall of the headstock housing 1 and are respectively arranged near the head and the middle of the headstock spindle 2. The bushing 6 is arranged between the front bearing 3 and the rear bearing 4 and is sleeved outside the headstock spindle 2. The locking nut 7 is arranged on the side of the rear bearing 4 away from the front bearing 3 and is threadedly connected to the headstock spindle 2. The bearing end cover 5 is installed at the connection between the headstock spindle 2 and the head of the headstock housing 1 and abuts against the front bearing 3, which is used to seal the connection between the headstock spindle 2 and the head of the headstock housing 1 and to limit the axial movement of the front bearing 3.

[0028] In this application, the headstock spindle 2 is installed in the headstock housing 1 through the front bearing 3 and the rear bearing 4. The front bearing 3 and the rear bearing 4 are supported by the bushing 6, and the axial movement of the front bearing 3 and the rear bearing 4 is restricted. At the same time, the axial movement of the front bearing 3 and the rear bearing 4 can be completely restricted through the locking nut 7, and the clearance between the front bearing 3 and the rear bearing 4 can be adjusted by adjusting the locking torque of the locking nut 7, so as to achieve high rotational accuracy.

[0029] As Figure 1As shown, the torque motor 8 is installed between the headstock housing 1 and the headstock spindle 2 and is disposed near the tail of the headstock spindle 2. The high-precision encoder 9 is arranged on the side of the torque motor 8 away from the rear end bearing 4.

[0030] In this application, the torque motor 8 functions to drive the rotation of the headstock spindle 2. The stator of the torque motor 8 is mounted on the headstock housing 1, and the rotor of the torque motor 8 is mounted on the headstock spindle 2. The high-precision encoder 9 is installed at the rear ends of the headstock housing 1 and the headstock spindle 2. The circular grating scale in the high-precision encoder 9 is mounted on the end cover connection plate and rotates together with the headstock spindle 2. The reading head in the high-precision encoder 9 is mounted on the headstock housing 1 through a connecting plate and remains stationary.

[0031] As Figures 1 - 2 shown, the pneumatic clamp 10 includes a clamp body disposed between the torque motor 8 and the rear end bearing 4, a clamping jaw 12 that fits against the outer wall of the headstock spindle 2, and a spring cortex 11 disposed inside the clamp body, connected to the clamping jaw 12 and having a predetermined elastic force.

[0032] In this application, the spring cortex 11 has a certain elastic force. The clamping jaw 12 is connected to the spring cortex 11. When the pneumatic clamp 10 is in operation, the clamping jaw 12 contacts the headstock spindle 2 to restrict the rotation of the headstock spindle 2. The pneumatic clamp 10 is disposed between the torque motor 8 and the locking nut 7 and is located in the middle and rear of the headstock housing 1, having two states: locking and releasing.

[0033] When the pneumatic clamp 10 is in the locked state, the clamping jaw 12 in the pneumatic clamp 10 contacts the headstock spindle 2, and the spring cortex 11 in the pneumatic clamp 10 generates an elastic force, so that the clamping jaw 12 clamps the headstock spindle 2. At this time, the headstock spindle 2 cannot rotate and remains in the current position.

[0034] When the pneumatic clamp 10 is in the released state, the clamping jaw 12 in the pneumatic clamp 10 separates from the headstock spindle 2. The inner air cavity of the spring cortex 11 in the pneumatic clamp 10 is filled with gas, causing the spring cortex 11 to arch, so that the clamping jaw 12 disengages from the headstock spindle 2. At this time, the headstock spindle 2 can rotate.

[0035] Meanwhile, when installing the pneumatic clamp 10, it is necessary to ensure the high coaxiality between the clamping jaw 12 and the headstock spindle 2. Otherwise, the internal structure of the pneumatic clamp 10 and the surface of the headstock spindle 2 will be damaged. When tightening the installation screws of the pneumatic clamp 10, it needs to be tightened in 3 steps. Each tightening must be carried out after the clamping jaw 12 contacts the headstock spindle 2. And the first tightening torque is 30% of the final tightening torque, the second tightening torque is 70% of the final tightening torque, and the third tightening torque is 100% of the final tightening torque.

[0036] As Figures 1 - 4As shown, an opening port and a closing port are also provided at a predetermined position on the pneumatic clamp 10.

[0037] In the initial state, the opening port on the pneumatic clamp 10 exhausts air, discharging the gas in the inner air cavity of the spring cortex 11, and the closing port intakes air, inflating and pressurizing the outer air cavity of the spring cortex 11. At this time, the spring cortex 11 is relaxed and extended, and the clamping jaw 12 contacts the headstock spindle 2, restricting the rotation of the headstock spindle 2. When the headstock spindle 2 needs to rotate, the opening port on the pneumatic clamp 10 intakes air, inflating and pressurizing the inner air cavity of the spring cortex 11, and the closing port exhausts air, discharging the gas in the outer air cavity of the spring cortex 11. At this time, the spring cortex 11 bends and arches, and the clamping jaw 12 separates from the headstock spindle 2. At this time, the headstock spindle 2 can rotate.

[0038] In addition, as Figures 3 - 4 shown, A1 and A2 are the codes of the solenoid valves, "1" and "0" are two different states of the solenoid valves, "1" indicates that the solenoid valve is energized at this time, and "0" indicates that the solenoid valve is de-energized at this time.

[0039] When A1 is 0 and A2 is 1, the opening port exhausts air and the closing port inflates. The compressed air in the inner air cavity of the spring cortex 11 is discharged, and the compressed air is filled into the outer air cavity of the spring cortex 11. The pneumatic clamp 10 is in the locked state.

[0040] When A1 is 1 and A2 is 0, the opening port inflates and the closing port exhausts air. The compressed air is filled into the inner air cavity of the spring cortex 11, and the compressed air in the outer air cavity of the spring cortex 11 is discharged. The pneumatic clamp 10 is in the relaxed state.

[0041] In this application, by adopting the high-precision front bearing 3 and rear bearing 4, the rotational accuracy of the headstock spindle 2 is improved, and closed-loop control is achieved. Through the precise control of the rotation speed and position of the headstock spindle 2, high-precision grinding of non-circular and threads can be realized, and the center height of the whole headstock is reduced, which can effectively utilize the center height and reduce the cost of the machine tool. At the same time, the protection performance of the internal structure of the whole headstock is enhanced, which is beneficial to improving the service life of the headstock and maintaining the high-precision performance for a long time. In actual use, the rotational accuracy of this application is less than 0.5 μm, the repeat accuracy is 1″, and the resolution is 0.00002°.

[0042] 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 to 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. A direct drive headstock for grinding precision non-circular and threaded workpieces, characterized in that, Including: A headstock housing, within which an installation cavity of a predetermined shape is provided; A headstock spindle, which is disposed within the headstock housing through the installation cavity. Front-end bearings and rear-end bearings are respectively provided between the headstock spindle and the inner wall of the headstock housing near the head and middle of the headstock spindle. Both the front-end bearing and the rear-end bearing adopt high-precision bearings to improve the rotational accuracy of the headstock spindle; A torque motor, which is installed between the headstock housing and the headstock spindle and is disposed near the tail of the headstock spindle to drive the headstock spindle to rotate. A high-precision encoder for controlling the rotational speed and position of the headstock spindle is provided on the side of the torque motor away from the rear-end bearing; A pneumatic clamp, including a clamp body disposed between the torque motor and the rear-end bearing, a clamping jaw that fits against the outer wall of the headstock spindle, and a spring cortex disposed within the clamp body, connected to the clamping jaw and having a predetermined elasticity; When the pneumatic clamp is in the locked state, the spring cortex in the pneumatic clamp generates an elastic force to clamp the headstock spindle with the clamping jaw; When the pneumatic clamp is in the relaxed state, the inner air cavity of the spring cortex in the pneumatic clamp is filled with gas, and the spring cortex arches to separate the clamping jaw from the headstock spindle.

2. The direct drive headstock for grinding precision non-circular and threaded workpieces according to claim 1, characterized in that: A bearing end cover is installed at the connection between the headstock spindle and the head of the headstock housing, and the bearing end cover abuts against the front-end bearing; The bearing end cover is used to seal the connection between the headstock spindle and the head of the headstock housing and to limit the axial movement of the front-end bearing.

3. The direct drive headstock for grinding precision non-circular and threaded workpieces according to claim 1, characterized in that: A sleeve is provided between the front-end bearing and the rear-end bearing, and the sleeve is sleeved outside the headstock spindle; The sleeve is used to limit the axial movement of the front-end bearing and the rear-end bearing.

4. The direct drive headstock for grinding precision non-circular and threaded workpieces according to claim 1, characterized in that: A locking nut is provided on the side of the rear-end bearing away from the front-end bearing, and the locking nut is threadedly connected to the headstock spindle; The locking nut is used to limit the axial movement of the rear-end bearing and to adjust the clearance of the rear-end bearing.

5. The direct drive headstock for grinding precision non-circular and threaded workpieces according to claim 1, characterized in that: The stator of the torque motor is installed on the headstock housing, and the rotor of the torque motor is installed on the headstock spindle.

6. The direct drive headstock for grinding precision non-circular and threaded workpieces according to claim 1, characterized in that: An opening and a closing port are also provided at a predetermined position on the pneumatic clamp; In the initial state, the opening on the pneumatic clamp exhausts air to discharge the gas in the inner air cavity of the spring cortex, and the closing port intakes air to inflate and pressurize the outer air cavity of the spring cortex. At this time, the spring cortex is relaxed and stretched, and the clamping jaw contacts and clamps the headstock spindle; When the headstock spindle needs to rotate, the opening on the pneumatic clamp intakes air to inflate and pressurize the inner air cavity of the spring cortex, and the closing port exhausts air to discharge the gas in the outer air cavity of the spring cortex. At this time, the spring cortex bends and arches to separate the clamping jaw from the headstock spindle.

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