Direct-drive B shaft for high-precision grinding center

Abstract

The utility model discloses a direct-drive B shaft for a high-precision grinding center, which relates to the field of grinding machines and comprises a B shaft box body, a high-precision main shaft bearing pack, a rotary disc, a clamping disc, a torque motor, a high-precision angle encoder and a pneumatic locking mechanism. By adopting the high-precision main shaft bearing pack, the rotation precision of the B-axis part can be improved; the torque motor is adopted for direct driving, so that the repeated positioning precision and the space utilization rate of the B-axis component are improved; a hydraulic locking structure is replaced by a pneumatic locking structure, after power and gas of a machine tool are cut off, the pneumatic locking structure can keep clamping force through a neutral position machine of an electromagnetic valve, damage to the machine tool and reduction of machining precision or scrapping of a workpiece are avoided, meanwhile, the purchase cost and maintenance cost of the machine tool are reduced, and the working efficiency is improved. The complexity of the machine tool structure is reduced; closed-loop control is achieved through the high-precision angle encoder, so that the positioning precision of the B-axis component is improved, and the grinding precision of a workpiece is improved.

Description

Technical Field

[0001] The utility model relates to the field of grinding machines, and particularly to a direct-drive B-axis for a high-precision grinding center. Background Art

[0002] The development of modern CNC machine tools is increasingly tending towards high speed, high precision, and intelligence. As a key component of a high-precision grinding center - the B-axis component, it also faces the need for high-precision development. The B-axis component mainly plays a role in driving the grinding wheel frame to rotate in the grinding center. The rotational accuracy and angular positioning accuracy will directly affect the accuracy of the workpiece after machining. For example, the cylinder surface becomes tapered, that is, the cylindricity becomes poor, the taper of the conical surface deviates from the drawing requirements, and the end face is not perpendicular to the workpiece rotation axis. After the B-axis rotates to a predetermined position, the locking structure in the B-axis takes effect and fixes the rotating disk at the current position.

[0003] The existing B-axis components mainly use an external motor to drive the worm and gear to make the B-axis rotate. This structure has poor repeat positioning accuracy and cannot be applied to high-precision grinding. Moreover, the rotational speed is slow and cannot adapt to high-speed grinding. And most of the bearings in the existing B-axis components use turntable bearings. Although this kind of bearing has good load-bearing performance, its rotational accuracy is poor, affecting the rotational accuracy of the B-axis component. At the same time, the existing B-axis uses a hydraulic locking structure to realize the function of fixing the rotating disk. This locking structure immediately loses the locking force when the machine tool is powered off (such as during transportation or emergency power-off). And after long-term use, the thin sheet for locking will fail due to excessive wear, resulting in damage to the machine tool or a decline in the machining quality of the workpiece or even scrapping due to the change of the B-axis angle. At the same time, the hydraulic locking structure is relatively complex, has high requirements for the working conditions, high costs, and impurities in the hydraulic oil will reduce the service life of the hydraulic valve, resulting in a high failure rate. Summary of the Utility Model

[0004] Purpose of the Utility Model: The utility model aims to provide a direct-drive B-axis for a high-precision grinding center to solve the above problems existing in the prior art.

[0005] Technical Solution: The direct-drive B-axis for a high-precision grinding center includes a B-axis housing, a high-precision spindle bearing group, a rotating disk, a clamping disk, a torque motor, a high-precision angle encoder, and a pneumatic locking mechanism;

[0006] Among them, the high-precision spindle bearing set is installed at a predetermined position within the B-axis box body. The rotating disk is connected to the high-precision spindle bearing set. The rotating disk is rotationally connected to the B-axis box body through the high-precision spindle bearing set. The clamping disk is installed on the rotating disk, and the clamping disk rotates following the rotating disk. The torque motor is installed between the rotating disk and the B-axis box body and is used to drive the rotation of the rotating disk. The high-precision angle encoder is connected between the rotating disk and the B-axis box body and is used to position the position of the rotating disk. The pneumatic locking mechanism is connected to the clamping disk, and the pneumatic locking mechanism is used to restrict the rotation of the clamping disk, thereby restricting the rotation of the rotating disk.

[0007] In a further embodiment, the stator of the torque motor is connected to the B-axis box body, and the rotor of the torque motor is connected to the rotating disk.

[0008] In a further embodiment, the rotating part in the high-precision angle encoder is connected to the rotating disk, which is used to accurately position the current position of the rotating disk and form a closed-loop control in cooperation with the corresponding control system, etc., to improve the execution accuracy of the overall component.

[0009] In a further embodiment, the high-precision spindle bearing set includes an upper high-precision spindle bearing and a lower high-precision spindle bearing;

[0010] The upper high-precision spindle bearing and the lower high-precision spindle bearing are respectively installed at corresponding positions between the rotating disk and the B-axis box body;

[0011] The upper high-precision spindle bearing and the lower high-precision spindle bearing are arranged in cooperation to ensure the rotation accuracy of the rotating disk.

[0012] In a further embodiment, the pneumatic locking mechanism includes a fixture body, a cavity, a piston rod, a clamping arm and a return spring;

[0013] Among them, the fixture body is installed at a predetermined position within the B-axis box body and is located outside the rotating disk; the cavity is arranged within the fixture body; the piston rod is slidably arranged within the fixture body; the clamping arm is movably arranged within the fixture body; the return spring is connected between the inner wall of the fixture body and the clamping arm; the return spring is used to drive the clamping arm to reset, and the return spring is used to drive the clamping arm to reset.

[0014] In a further embodiment, the pneumatic locking mechanism further includes a locking port and a relaxation port;

[0015] Wherein, the locking port is opened at a predetermined position on the fixture body and communicates with the cavity, the relaxation port is opened at a predetermined position on the fixture body and communicates with the cavity, and the relaxation port is arranged corresponding to the locking port;

[0016] When the pneumatic locking mechanism is in the locked state, the locking port admits air, and at the same time the relaxation port exhausts air, causing the piston rod to move to the right. At this time, the clamping arm contacts the clamping disc, restricting the rotation of the clamping disc, and thus restricting the rotation of the rotary disc;

[0017] When the pneumatic locking mechanism is in the relaxed state, the relaxation port admits air, and at the same time the locking port exhausts air, causing the piston rod to move to the left. At this time, the clamping arm separates from the clamping disc, releasing the restriction on the clamping disc, and thus releasing the restriction on the rotary disc.

[0018] Beneficial effects: The present utility model discloses a direct-drive B-axis for a high-precision grinding center. By adopting a high-precision main shaft bearing group, the rotary precision of the B-axis component can be improved; by adopting a torque motor direct drive, the transmission error can be reduced to zero, improving the repeat positioning precision and the space utilization rate of the B-axis component; by adopting a pneumatic locking structure instead of a hydraulic locking structure, after the machine tool is powered off and the air supply is cut off, the pneumatic locking mechanism realizes the retention of the clamping force through the middle position function of the solenoid valve, avoiding damage to the machine tool and the decline or scrapping of the machining precision of the workpiece, etc., and at the same time reducing the procurement cost and maintenance cost of the machine tool and reducing the complexity of the machine tool structure; by adopting a high-precision angle encoder to achieve closed-loop control, the positioning precision of the shaft component is improved, and thus the grinding precision of the workpiece is improved, etc. Description of the Drawings

[0019] Figure 1 It is a schematic cross-sectional structure diagram of the present utility model.

[0020] Figure 2 It is an exploded structure diagram of the present utility model.

[0021] Figure 3 It is a schematic structure diagram of the pneumatic locking mechanism of the present utility model.

[0022] Figure 4 It is a schematic diagram of the principle when the pneumatic locking mechanism of the present utility model is locked.

[0023] Figure 5 It is a schematic diagram of the principle when the pneumatic locking mechanism of the present utility model is relaxed.

[0024] Figure 6 It is a schematic diagram of the principle when the pneumatic locking mechanism of the present utility model is powered off and the air supply is cut off.

[0025] The reference numerals in the figures are as follows: 1, rotary disk; 2, upper high-precision spindle bearing; 3, torque motor; 4, lower high-precision spindle bearing; 5, B-axis housing; 6, pneumatic locking mechanism; 601, fixture body; 602, cavity; 603, piston rod; 604, clamping arm; 605, return spring; 7, clamping disk; 8, high-precision angle encoder. Detailed implementation manners

[0026] In the following description, numerous specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other instances, some well-known technical features are not described to avoid confusion with the present invention.

[0027] First, it should be clear that the B-axis (rotating along the Y-axis, which is used to drive the grinding headstock and the grinding wheel spindle and the grinding wheel housing mounted on the grinding headstock to rotate) is a common term in the field of grinding machines and is also the national standard term. In the field of grinding machines, the name of the B-axis is clear and will not cause ambiguity.

[0028] The existing B-axis components mainly use an external motor to drive a worm and worm gear to make the B-axis rotate. This structure has poor repeat positioning accuracy and cannot be applied to high-precision grinding. Moreover, the rotation speed is slow and it cannot adapt to high-speed grinding. And the existing B-axis components mainly use turntable bearings. Although these bearings have good load-bearing performance, their rotation accuracy is poor and it is easy to affect the rotation accuracy of the B-axis components. At the same time, the existing B-axis uses a hydraulic locking structure to realize the function of fixing the rotary disk. This locking structure immediately loses the locking force when the machine tool is powered off (such as during transportation or emergency power-off). And in the long-term use, the thin sheet for locking will fail due to excessive wear, resulting in damage to the machine tool or a decline in the machining quality of the workpiece or even scrapping due to the change of the B-axis angle. At the same time, the hydraulic locking structure is relatively complex, has high requirements for the working conditions, high cost, and the impurities in the hydraulic oil will reduce the service life of the hydraulic valve, resulting in a high failure rate.

[0029] Therefore, this embodiment proposes a direct-drive B-axis for a high-precision grinding center, as Figures 1 - 3 shown. This direct-drive B-axis is composed of a B-axis housing 5, a high-precision spindle bearing group, a rotary disk 1, a clamping disk 7, a torque motor 3, a high-precision angle encoder 8, and a pneumatic locking mechanism 6.

[0030] Among them, the high-precision spindle bearing group is installed at a predetermined position inside the B-axis housing 5. The rotary disk 1 is connected to the high-precision spindle bearing group. The rotary disk 1 is rotationally connected to the B-axis housing 5 through the high-precision spindle bearing group. The clamping disk 7 is installed on the rotary disk 1 and rotates with the rotary disk 1. The torque motor 3 is installed between the rotary disk 1 and the B-axis housing 5 and is used to drive the rotary disk 1 to rotate. The high-precision angle encoder 8 is connected between the rotary disk 1 and the B-axis housing 5 and is used to position the rotary disk 1. The pneumatic locking mechanism 6 is connected to the clamping disk 7 and is used to restrict the rotation of the clamping disk 7, thereby restricting the rotation of the rotary disk 1.

[0031] In this application, the high-precision spindle bearing group includes an upper high-precision spindle bearing 2 and a lower high-precision spindle bearing 4. The upper high-precision spindle bearing 2 and the lower high-precision spindle bearing 4 are respectively installed at corresponding positions between the rotary disk 1 and the B-axis housing 5. The rotary disk 1 is installed on the upper high-precision spindle bearing 2 and the lower high-precision spindle bearing 4, and the rotary disk 1 rotates relative to the B-axis housing 5. The upper high-precision spindle bearing 2 and the lower high-precision spindle bearing 4 are arranged in cooperation to ensure the rotational accuracy of the rotary disk 1 and are also key components to ensure the accuracy of the entire B-axis component. The torque motor 3 is installed between the rotary disk 1 and the B-axis housing 5, and the stator and rotor of the torque motor 3 are respectively fixedly connected to the B-axis housing 5 and the rotary disk 1. It is the driving component of the B-axis component, which can achieve benefits such as saving space, reducing the transmission structure, and improving the repeat positioning accuracy. The high-precision angle encoder 8 is installed on the B-axis housing 5, and the rotating part in the high-precision angle encoder 8 is connected to the rotary disk 1, which can accurately position the current position of the rotary disk 1 and form a closed-loop control in cooperation with the corresponding control system, etc., to improve the execution accuracy of the B-axis component.

[0032] This patent proposes a new structure of the B-axis component to solve the problems of poor repeat positioning accuracy of the B-axis component, poor rotational accuracy of the B-axis component, the problem that the thin sheet used for locking in the hydraulic locking structure is excessively worn and fails, the problem that the hydraulic locking structure is relatively complex, has high requirements for the working conditions, high cost, and the impurities in the hydraulic oil will reduce the service life of the hydraulic valve, resulting in a relatively high failure rate, etc.

[0033] As Figures 1 - 6 shown, the pneumatic locking mechanism 6 includes a fixture body 601, a cavity 602, a piston rod 603, a clamping arm 604, a return spring 605, a locking port, and a release port.

[0034] Among them, the fixture body 601 is installed at a predetermined position inside the B-axis box body 5 and is located outside the turntable 1. The cavity 602 is arranged inside the fixture body 601. The piston rod 603 is slidably arranged inside the fixture body 601. The clamping arm 604 is movably arranged inside the fixture body 601. The return spring 605 is connected between the inner wall of the fixture body 601 and the clamping arm 604. The return spring 605 is used to drive the clamping arm 604 to reset. The locking port is opened at a predetermined position on the fixture body 601 and is communicated with the cavity 602. The release port is opened at a predetermined position on the fixture body 601 and is communicated with the cavity 602. The release port and the locking port are arranged corresponding to each other.

[0035] In this application, the fixture body 601 is installed at a predetermined position inside the B-axis box body 5 and is located outside the turntable 1. The cavity 602 is arranged inside the fixture body 601. The cavity 602 is a closed space and can only intake or exhaust air through the locking port and the release port. The piston rod 603 is arranged inside the fixture body 601. The piston rod 603 can move left and right inside the cavity 602. The clamping arm 604 is arranged inside the fixture body 601 and is used to clamp the clamping disc 7. The return spring 605 is arranged inside the fixture body 601 and is used to drive the clamping arm 604 to reset.

[0036] In this application, the pneumatic locking mechanism 6 is installed on the B-axis box body 5 and has two states: locking and releasing.

[0037] When the pneumatic locking mechanism 6 is in the locking state, the clamping arm 604 in the pneumatic locking mechanism 6 contacts the clamping disc 7. The piston rod 603 in the pneumatic locking mechanism 6 moves to generate a top force, thereby locking the clamping disc 7. At this time, the turntable 1 cannot rotate and remains in the current position.

[0038] When the pneumatic locking mechanism 6 is in the release state, the clamping arm 604 in the pneumatic locking mechanism 6 separates from the clamping disc 7. The right air chamber of the piston rod 603 in the pneumatic locking mechanism 6 is filled with gas, causing the piston rod 603 to move to the right, thereby enabling the clamping arm 604 to disengage from the clamping disc 7. At this time, the turntable 1 can rotate.

[0039] Specifically, the piston rod 603 has a certain top force due to the compressed air in the cavity 602. When the pneumatic locking mechanism 6 takes effect, the locking port on the pneumatic locking mechanism 6 intakes air and the release port exhausts air, causing the piston rod 603 to move to the right, making the clamping arm 604 contact the clamping disc 7 and restricting the rotation of the turntable 1.

[0040] When the turntable 1 needs to rotate, the locking port on the pneumatic locking mechanism 6 exhausts air and the release port intakes air, causing the piston rod 603 to move to the left, the clamping arm 604 to separate from the clamping disc 7, and the turntable 1 to be able to rotate.

[0041] In addition, when installing the pneumatic locking mechanism 6, it is necessary to ensure a high degree of parallelism between the mating surface of the clamping arm 604 and the clamping disc 7 and the installation surface of the pneumatic locking mechanism 6. Otherwise, the clamping force will be uneven, resulting in a reduction in the bearing life. During installation, the clamping disc 7 is first installed on the lower side of the rotary disc 1, and then the clamping arm 604 of the pneumatic locking mechanism 6 is reset before installation.

[0042] In addition, as Figures 4 - 6 shown, where A1 and A2 are the designations of the coils in the solenoid valve, and "1" and "0" are two different states of the coils in the solenoid valve. "1" indicates that the coil is energized at this time, and "0" indicates that the coil is de-energized at this time.

[0043] When A1 is 1 and A2 is 0, the locking port intakes air, the release port exhausts air, the left air chamber of the piston rod 603 is inflated, and the right air chamber of the piston rod 603 exhausts air, causing the piston rod 603 to move to the left, and the pneumatic locking mechanism 6 is in the locked state.

[0044] When A1 is 0 and A2 is 1, the locking port exhausts air, the release port intakes air, the left air chamber of the piston rod 603 exhausts air, and the right air chamber of the piston rod 603 intakes air, causing the piston rod 603 to move to the right, and the pneumatic locking mechanism 6 is in the released state.

[0045] When the machine tool suddenly loses power and air supply during operation, that is, A1 is 0 and A2 is 0, the solenoid valve is in the middle position state. Since the function of the middle position state is that each port is closed, the pneumatic locking mechanism 6 can be maintained in the locked state to protect the machine tool from damage and avoid the decline or scrapping of the machining accuracy of the workpiece.

[0046] Compared with the hydraulic locking structure, the pneumatic locking mechanism 6 is relatively simple, and its installation and maintenance are also relatively simple and convenient. At the same time, the cost of the air circuit components and pipelines is also relatively low.

[0047] 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 to it in form and detail without departing from the spirit and scope of the present invention defined by the appended claims.

Claims

1. A direct-drive B-axis for a high-precision grinding center, characterized in that, Comprising: B-axis housing; A high-precision spindle bearing set, installed at a predetermined position within the B-axis housing; A rotating disk, connected to the high-precision spindle bearing set, and the rotating disk is rotationally connected to the B-axis housing through the high-precision spindle bearing set; A clamping disk, installed on the rotating disk, and the clamping disk rotates following the rotating disk; A torque motor, installed between the rotating disk and the B-axis housing, for driving the rotation of the rotating disk; A high-precision angle encoder, connected between the rotating disk and the B-axis housing, for positioning the position of the rotating disk; A pneumatic locking mechanism, connected to the clamping disk; The pneumatic locking mechanism is used to restrict the rotation of the clamping disk, thereby restricting the rotation of the rotating disk.

2. The direct drive B-axis for a high-precision grinding center according to claim 1, characterized in that: The stator of the torque motor is connected to the B-axis housing, and the rotor of the torque motor is connected to the rotating disk.

3. The direct drive B-axis for a high-precision grinding center according to claim 1, characterized in that: The rotating part in the high-precision angle encoder is connected to the rotating disk, for accurately positioning the current position of the rotating disk.

4. The direct drive B-axis for a high-precision grinding center according to claim 1, characterized in that: The high-precision spindle bearing set includes an upper high-precision spindle bearing and a lower high-precision spindle bearing; The upper high-precision spindle bearing and the lower high-precision spindle bearing are respectively installed at corresponding positions between the rotating disk and the B-axis housing; The upper high-precision spindle bearing and the lower high-precision spindle bearing are cooperatively arranged to ensure the rotational accuracy of the rotating disk.

5. The direct drive B-axis for a high-precision grinding center according to claim 1, characterized in that: The pneumatic locking mechanism includes a fixture body, a cavity, a piston rod, a clamping arm and a return spring; The fixture body is installed at a predetermined position within the B-axis housing and is located outside the rotating disk; the cavity is arranged within the fixture body; the piston rod is slidably arranged within the fixture body; the clamping arm is movably arranged within the fixture body; the return spring is connected between the inner wall of the fixture body and the clamping arm; The clamping arm is used to clamp the clamping disk, and the return spring is used to drive the clamping arm to reset.

6. The direct drive B-axis for a high-precision grinding center according to claim 5, characterized in that: The pneumatic locking mechanism further includes a locking port and a relaxation port; The locking port is opened at a predetermined position on the fixture body and is communicated with the cavity; The relaxation port is opened at a predetermined position on the fixture body and is communicated with the cavity, and the relaxation port is arranged corresponding to the locking port.

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