Machine tool power head

Abstract

The utility model discloses a power head of a machine tool, which belongs to the technology of the machine tool, solves the problem that the existing screw thread grinder is difficult to meet the high-precision processing requirement, and is characterized in that one axial end of an outer rotor is arranged on a clamp for clamping a workpiece and driving the workpiece to rotate, and an inner stator is fixed on a base at the other axial end of the outer rotor; the sensor is arranged between the outer rotor and the inner stator, the positioning device is directly or indirectly fixed to the base or the inner stator, and the positioning center line of the positioning device coincides with the rotating center line of the outer rotor. The theoretical error of radial run-out of the positioning device is zero, and run-out errors caused by radial run-out of the positioning device during workpiece machining are avoided, and machining errors of machined workpieces are prevented from being reflected. And through the high rotation precision of the outer rotor, the arc-second-level precise control is realized. The positioning device positions a machined workpiece, the outer rotor drives the workpiece to rotate through the clamp, the positioning device and the outer rotor are divided in function, and the machine tool power head is endowed with the capacity of being very small in positioning error and very high in rotating precision.

Description

TECHNICAL FIELD

[0001] The utility model belongs to machine tool technology, concretely relates to a machine tool power head for accurately positioning workpieces and driving the workpieces to rotate to implement precision machining on the workpieces. BACKGROUND

[0002] With the increasingly high precision of the precision lead screw grinding requirement, the original technology is difficult to meet the grinding requirement.

[0003] The existing lead screw grinding basically positions the center hole of the two shaft ends of the lead screw and drives the lead screw to rotate by the power head. Since the center follows the rotation of the power head spindle, the runout error of the taper surface of the center is reflected to the machining error of the machined workpiece. Another original thread grinder can keep the center still, but when the power of the thread grinder drives the workpiece to rotate through the transmission mechanism such as belt transmission and gear transmission, the rotation accuracy of the transmission mechanism is far from enough, and it cannot achieve the "angle second" level of accuracy. Therefore, there is no machine tool power head with very small positioning error and very high rotation accuracy in the prior art. CONTENT OF THE UTILITY MODEL

[0004] The utility model discloses a machine tool power head with very small positioning error and very high rotation accuracy to overcome the defects that the existing lead screw thread grinder is difficult to meet the high-precision machining requirement.

[0005] To achieve the above-mentioned purpose, the machine tool power head of the utility model, including base, outer rotor, inner stator, sensor and positioning device, the outer rotor is sleeved on the radial outer side of the inner stator to rotate around the inner stator by the action of the inner stator rotating magnetic field, and its characteristics are that: the one end of the axial direction of the outer rotor is provided with a clamp for clamping the workpiece and driving the workpiece to rotate, the other end of the axial direction of the outer rotor is fixed on the base, the sensor is arranged between the outer rotor and the inner stator, the positioning device is directly or indirectly fixed on the base or the inner stator, and the positioning center line of the positioning device coincides with the rotation center line of the outer rotor.

[0006] Among them, the inner stator can be fixed on the base axially, radially or both axially and radially.

[0007] The machine tool power head, by fixing the positioning device, the positioning center line of the positioning device coincides with the rotation center line of the outer rotor, makes the radial runout theoretical error of the positioning device to be 0, avoids the radial runout of the positioning device when machining the workpiece to produce runout error and reflects to the machining error of the machined workpiece. Through the high rotation accuracy of the outer rotor in the circumferential direction, the "angular second" level of accuracy control is realized. The positioning device positions the machined workpiece, the outer rotor rotates with the workpiece through the clamp, the 0 error positioning of the positioning device and the "angular second" level of circumferential rotation of the outer rotor are functionally divided, and the machine tool power head is given the ability of very small positioning error and very high rotation accuracy.

[0008] Preferably, in order to configure the structure of the machine tool power head, the inner stator is directly or indirectly fixed and assembled to the base. The inner stator can be configured on the base as needed to adapt to the structure and machining requirements on the entire machine tool.

[0009] In one embodiment, the center of the inner stator has a stator taper hole, and the positioning device is assembled to the stator taper hole through a handle portion with a taper. Accordingly, the power head structure is simple, while the concentricity of the positioning device and the outer rotor can be ensured, the assembly error of the machine tool power head is reduced, and the machining accuracy is ensured.

[0010] In another embodiment, the base has a cylindrical portion, the center of the cylindrical portion has a base taper hole, the positioning device is assembled to the base taper hole through a handle portion with a taper, and the inner stator is sleeved on the radial outer side of the cylindrical portion. In this structure, the inner stator has a gap with the base cylindrical portion, which facilitates heat dissipation of the inner stator; at the same time, the cylindrical portion and the base body are designed in an integrated manner, which increases the rigidity of the overhanging cylindrical portion and avoids the micro-vibration error that may be generated after the positioning device is installed on the cylindrical portion.

[0011] Preferably, the outer rotor and the inner stator constitute a direct drive motor, which is commonly referred to as DD motor (Direct Drive Motor), and the controller controls the direct drive motor according to the feedback signal of the sensor. Accordingly, a direct drive motor with appropriate technical specifications can be selected as needed to meet the accuracy requirements of rotary drive. Specifically, the sensor is used to sense the speed, position and load of the motor and other information. The controller is responsible for controlling and adjusting the motor. That is, through the feedback of the sensor, the controller supplies appropriate current to the motor according to the set parameters and algorithms according to the feedback signal of the sensor, and accurately controls the motor. Common sensors include Hall sensors, photoelectric sensors and magnetic encoders.

[0012] Preferably, the positioning device is a center, and the head of the center is an outwardly convex structure or an inwardly concave structure. To adapt to the end of different structural forms of the machined workpiece.

[0013] Preferably, the positioning device is provided with a shank having a taper; the shank is positioned by being fitted into the taper hole of the base or the stator taper hole of the inner stator. The taper of the shank is preferably a Morse taper. Because the taper is very small, a certain torque can be transmitted by using the principle of friction. Because it is a taper fit, the shank can be easily disassembled. Within a certain range of the same taper, the workpiece can be freely disassembled and assembled, and at the same time, the use effect will not be affected during work. When the positioning device needs to be disassembled during use, the disassembly and reassembly will not affect the center position of the positioning device.

[0014] Preferably, the center axis of the base taper hole or the center axis of the stator taper hole of the inner stator coincides with the rotation center line of the outer rotor. In this way, the concentricity of the positioning device, the outer rotor and the clamp is ensured, and the assembly error of the machine tool power head is reduced. By cleverly designing the clamp, the possible small error in the concentricity of the outer rotor and the clamp can be reduced to 0, and the machining accuracy can be maximized.

[0015] Preferably, the positioning center of the positioning device is the geometric axis of the center. In this way, the positioning device is regular in shape and can reliably and accurately support the workpiece being machined.

[0016] Preferably, the sensor includes a reading head and an encoder or a circular grating for reading dynamic signals by the reading head. The reading head is directly or indirectly fixed to the inner stator or / and the base, and the encoder or the circular grating is directly or indirectly fixed to the outer rotor. In this way, when the outer rotor rotates, the encoder or the circular grating rotates with it and reflects the rotation dynamics of the outer rotor. The reading head reads the dynamic signals from the rotation of the encoder or the circular grating to obtain the rotation data of the outer rotor, which is provided to the controller to control the rotation of the outer rotor by the rotating magnetic field of the inner stator.

[0017] The utility model discloses a positioning device for machine tool power head, which comprises an outer rotor, an inner stator, a sensor, a clamp and a positioning device. The outer rotor is fixed to the base through the clamp. The inner stator is fixed to the base. The sensor is arranged between the outer rotor and the inner stator. The positioning device is directly or indirectly fixed to the base or the inner stator. The positioning center line of the positioning device coincides with the rotation center line of the outer rotor. The radial runout theoretical error of the positioning device is 0, which avoids the radial runout of the positioning device during machining of the workpiece and the machining error of the workpiece. Through the high rotation accuracy of the outer rotor, the "angular second" level of accurate control is realized. The positioning device positions the workpiece, and the outer rotor rotates with the workpiece through the clamp. The 0 error positioning of the positioning device and the "angular second" level of circumferential accurate rotation of the outer rotor are functionally divided, which gives the machine tool power head the ability of very small positioning error and very high rotation accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1It is the cross section structure schematic drawing of the machine tool power head of the embodiment 1 of the utility model;

[0019] Figure 2 It is the cross section structure schematic drawing of the base in Figure 1 ;

[0020] Figure 3 It is the cross section structure schematic drawing of the inner stator in Figure 1 ;

[0021] Figure 4 It is the cross section structure schematic drawing of the machine tool power head of the embodiment 2 of the utility model;

[0022] Figure 5 It is the cross section structure schematic drawing of the base in Figure 4 ;

[0023] Figure 6 It is a structure schematic drawing of the positioning device of the utility model;

[0024] Figure 7 It is another structure schematic drawing of the positioning device of the utility model;

[0025] Figure 8 It is the enlarged view of A part in Figure 1 ;

[0026] Mark number explanation in drawing:

[0027] 1 outer rotor, 11 rotation center line;

[0028] 2 base, 21 base taper hole, 22 center axis, 23 barrel portion, 24 elevation;

[0029] 3 inner stator, 31 stator taper hole, 32 center axis, 33 end face, 34 skirt, 35 gap;

[0030] 4 sensor, 41 round grating, 42 reading head;

[0031] 5 positioning device, 51 head, 52 handle, 53 positioning center line;

[0032] 6 clamp;

[0033] 7 workpiece. Specific implementation

[0034] In order to make the purpose, technical scheme and advantages of the utility model clearer, the technical scheme in the utility model embodiment will be clearly and completely described below in combination with the drawings in the utility model embodiment. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0035] The terms "comprising" and "having" and any variations thereof in the specification and claims of the utility model are intended to cover non-exclusive inclusion, for example, a method or product comprising a series of technical features does not have to be limited to the clearly listed technical features, and other technical features that can be included in the method or product without being clearly listed can also be included.

[0036] The utility model will be described in detail below in combination with specific embodiments and drawings.

[0037] Embodiment 1

[0038] As Figure 1 shown, the machine tool power head comprises a base 2, an outer rotor 1, an inner stator 3, a sensor 4 and a positioning device 5, the outer rotor 1 is sleeved on the radial outer side of the inner stator 3 to rotate around the inner stator 3 by the action of the rotating magnetic field of the inner stator 3. One end of the outer rotor 1 in the axial direction is assembled to clamp the workpiece and drive the workpiece 7 to rotate by the clamp 6, and the other end of the inner stator 3 in the axial direction of the outer rotor 1 is fixed to the base 2. The sensor 4 is arranged between the outer rotor 1 and the inner stator 3, the positioning device 5 is directly fixed to the inner stator 3 by a fastener, and the positioning center line 53 of the positioning device 5 coincides with the rotation center line 11 of the outer rotor 1.

[0039] The machine tool power head, by fixing the positioning device, the positioning center line of the positioning device coincides with the rotation center line of the outer rotor, the radial runout theoretical error of the positioning device is 0, the radial runout of the positioning device is avoided when the workpiece is machined, and the runout error is reflected to the machining error of the machined workpiece. Through the high-precision rotation of the outer rotor, the "angular second" level of accurate control is realized.

[0040] The machine tool power head, the positioning device positions the machined workpiece, the outer rotor rotates with the workpiece through the clamp, the positioning device and the outer rotor functionally divide the work, and the machine tool power head has the ability of very small positioning error and very high rotation accuracy.

[0041] In this embodiment, the end face 33 of the inner stator 3 is attached to the vertical face 24 of the base and is fixed by fasteners, i.e. the inner stator is axially fixed to the base. In other embodiments, a third component can be arranged between the end face 33 of the inner stator 3 and the vertical face 24 of the base to indirectly fasten the inner stator to the base. The inner stator 3 has a stator taper hole 31 in the center, and the positioning device 5 is fitted into the stator taper hole 31 via a handle 52 with a taper. In this way, the concentricity of the positioning device 5 with the outer rotor 1 and the clamp 6 can be ensured, the assembly error of the machine tool power head can be reduced, and the machining accuracy can be ensured.

[0042] Figure 1 、 Figure 4 The clamp 6 is only a schematic diagram and only represents a component that drives the workpiece 7 to rotate circumferentially via the "clamp", and does not represent a specific clamp structure.

[0043] In this embodiment, the outer rotor 1 and the inner stator 3 form a direct drive motor, which is commonly referred to as a DD motor (Direct Drive Motor), and the controller controls the direct drive motor according to the feedback signal of the sensor 4. In this way, a direct drive motor with appropriate technical specifications can be selected as needed to meet the accuracy requirements of rotational driving.

[0044] The sensor 4 is used to sense the speed, position, and load of the motor, etc. The controller is responsible for controlling and adjusting the motor. That is, the working information of the motor is obtained and fed back through the sensor, and the controller supplies appropriate current to the motor according to the feedback signal of the sensor and the set parameters and algorithms to accurately control the motor. Common sensors include Hall sensors, photoelectric sensors, and magnetic encoders, etc.

[0045] In this embodiment, the positioning device 5 is provided with a handle 52, and the handle 52 has a taper. The handle 52 is positioned by being installed in the stator taper hole 31 of the inner stator 3 through a static fit. The taper of the handle 52 and the stator taper hole 31 is preferably a Morse taper. Since the Morse taper is very small, a certain torque can be transmitted by using the principle of friction. Moreover, since it is a taper fit, it can be easily disassembled. Within a certain range of the same taper, the positioning device can be freely disassembled, while not affecting the use effect during work. In use, the disassembled positioning device can be reassembled without affecting the central position of the positioning device.

[0046] The central axis 32 of the stator taper hole 31 of the inner stator 3 coincides with the rotation center line 11 of the outer rotor 1. In this way, the concentricity of the positioning device with the outer rotor and the clamp can be ensured, the assembly error of the machine tool power head can be reduced, and the machining accuracy can be ensured.

[0047] In this embodiment, the positioning device 5 is a center, and the head 51 of the center is like Figure 6The head part 51 is shown as a convex structure. The end part of the concave structure for supporting the workpiece to be processed. According to the end structure of the workpiece to be processed, such as the end part of the workpiece to be processed as a convex structure, the positioning device 5 is selected Figure 7 The head part 51 is shown as a concave structure of the positioning device.

[0048] In this embodiment, the positioning center line 53 of the positioning device 5 is the geometric axis of the center of the tailstock. Accordingly, the positioning device is guaranteed to be regular in shape, and can reliably and accurately support the workpiece to be processed.

[0049] In this embodiment, the sensor 4 is shown as Figure 8 The head part 51 is shown as a concave structure of the positioning device.

[0050] The machine tool power head of this embodiment, when grinding the workpiece (such as a lead screw), installs the shaft end of the workpiece (such as a lead screw) on the head part of the positioning device 5. Since the positioning device is fixedly connected with the inner stator, the rotational runout error of the positioning device is almost 0 when the vibration factor of the machine tool is ignored. The workpiece (such as a lead screw) is clamped by a clamp and rotated with the clamp. The outer rotor and the inner stator constitute a direct drive motor, which has accurate rotation precision and meets the precision requirements of the lead screw.

[0051] Embodiment 2

[0052] As shown in Figure 4 The machine tool power head is shown as in embodiment 1, and also includes a base 2, an outer rotor 1, an inner stator 3, a sensor 4 and a positioning device 5. Compared with embodiment 1, this embodiment has the following differences:

[0053] In this embodiment, the base 2 has a cylindrical part 23, the center of the cylindrical part 23 has a base taper hole 21, the positioning device 5 is assembled to the base taper hole 21 of the base 2 through the handle part 52 with a taper, and the center axis 22 of the base taper hole 21 of the base coincides with the rotation center line 11 of the outer rotor 1. The inner stator 3 is sleeved on the radially outer side of the cylindrical part 23 and directly fastened and assembled to the vertical surface of the base through the end face, that is, the inner stator 3 is axially fixed to the base 2. In this structure, the inner stator 3 is radially positioned and installed at the vertical surface 24 of the base through the radially outer side of the skirt 34 of the end part, ensuring the concentricity of the inner stator 3 and the cylindrical part 23, indirectly ensuring the concentricity of the positioning device 5 and the outer rotor 1, reducing the assembly error of the machine tool power head, and ensuring the machining precision.

[0054] In this embodiment, there is a gap 35 between the inner stator 3 and the cylindrical portion 23 of the base, which facilitates heat dissipation of the inner stator; at the same time, the cylindrical portion and the base body are designed in an integrated manner, which increases the rigidity of the overhanging cylindrical portion and avoids the micro-vibration error that may be caused by the installation of the positioning device in the cylindrical portion.

[0055] In this embodiment, the reading head 42 is directly or indirectly fixed to the base.

[0056] The remaining structure of this embodiment is the same as that of Embodiment 1 and will not be described again.

[0057] When grinding a workpiece (such as a screw rod), the machine tool power head of this embodiment also installs the shaft end of the workpiece (such as a screw rod) on the head of the positioning device 5. Since the positioning device is fixedly connected to the base, the rotational runout error of the positioning device is almost 0 under the condition of neglecting the machine tool vibration factor. The workpiece (such as a screw rod) is clamped by a clamp and rotated. The outer rotor and the inner stator constitute a direct drive motor, which has accurate rotation precision and meets the precision requirements of the screw rod.

[0058] In the foregoing embodiments, the positioning device is exemplified by a center as an example to support and position the workpiece. In other embodiments, other structural forms of positioning devices equivalent to the center can be selected to support and position the workpiece.

Claims

1. Machine tool power head comprising a base (2), an outer rotor (1), an inner stator (3), a sensor (4) and a positioning device (5), the outer rotor (1) being housed radially outside the inner stator (3) to rotate around the inner stator (3) by the action of the magnetic field of the inner stator (3), characterized in that: The outer rotor (1) is provided with a chuck (6) at one axial end for clamping a workpiece and driving the workpiece (7) to rotate, the inner stator (3) is fixed to the base (2) at the other axial end of the outer rotor (1), the sensor (4) is arranged between the outer rotor (1) and the inner stator (3), the positioning device (5) is directly or indirectly fixed to the base (2) or the inner stator (3), and the positioning center line (53) of the positioning device (5) coincides with the rotation center line (11) of the outer rotor (1).

2. A machine tool power head according to claim 1, characterised in that: The inner stator (3) is directly or indirectly fixed and assembled to the base (2) in the axial direction or / and the radial direction.

3. A machine tool power head according to claim 1 or 2, characterised in that: The inner stator (3) has a stator taper hole (31) at the center, and the positioning device (5) is assembled to the stator taper hole (31) through a tapered shank (52).

4. A machine tool power head according to claim 1 or 2, characterised in that: The base (2) has a cylindrical portion (23) with a base taper hole (21) at the center, and the positioning device (5) is assembled to the base taper hole (21) through a tapered shank (52), and the inner stator (3) is sleeved on the radial outer side of the cylindrical portion (23).

5. The machine tool power head of claim 1, wherein: The outer rotor (1) and the inner stator (3) form a direct drive motor, and the controller controls the direct drive motor according to the feedback signal of the sensor.

6. The machine tool power head of claim 1, wherein: The positioning device (5) is a center, and the head (51) of the center is an outward convex structure or an inward concave structure.

7. A machine tool power head according to claim 6, characterised in that: The positioning device (5) is provided with a shank (52) having a taper; and the shank (52) is positioned by being mounted in the base taper hole (21) of the base (2) or the stator taper hole (31) of the inner stator by static fit.

8. A machine tool power head according to claim 7, characterised in that: The center axis of the base taper hole (21) of the base (2) or the center axis of the stator taper hole (31) of the inner stator coincides with the rotation center line of the outer rotor (1).

9. A machine tool power head according to any one of claims 6 to 8, wherein: The positioning center line (53) of the positioning device (5) is the geometric axis of the center.

10. The machine tool power head of claim 1, wherein: The sensor (4) includes a reading head (42) and an encoder or circular grating (41) for reading dynamic signals by the reading head (42), the reading head (42) is directly or indirectly fixed to the inner stator (3) or / and the base (2), and the encoder or circular grating (41) is directly or indirectly fixed to the outer rotor (1).

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