JPH05153757A - Linear motion table with built-in motor - Google Patents

Abstract

PURPOSE:To facilitate miniaturization, high speed control, reduction of the number of parts, small noise and an assembly process of a linear motion table. CONSTITUTION:A stator 40 is fitted to a table 30, and a rotor 20 is coaxially arranged in the stator 40 by two bearings 44. When the rotor 20, connected to be screwed to a ball screw 10, is rotated, the rotor 20 is moved to right/left on the ball screw 10 to move the table 30. Since the table 30 is directly controlled not through the ball screw 10, position control at a high speed can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion table with a built-in motor, which is used for feeding a table of a metal working machine or feeding a sample of a measuring instrument. Regarding linear motion table.

[0002]

2. Description of the Related Art Referring to FIG. 4, a conventional linear motion table comprises a slider block (50) and a motor (70) for driving the slider block (50). The slider block (50) is provided with a ball screw (52) and first and second support units (54) (54) (60) having bearings (56) (60) for pivotally supporting the ball screw (52) at substantially both shaft ends. 58), a ball nut (62) provided with a flange (64), and a table (66) provided with a fitting groove (68) for the ball nut (62).
(70) is a rotor (72) and a rotor shaft (74), a front bracket (76) equipped with respective bearings (78) (82) for supporting the rotor shaft (74) at substantially both shaft ends, and a motor Install the rotor (7) in the frame (80) and motor frame (80).
It is composed of a stator (84) arranged concentrically with 2). Attach the front bracket (76) to the motor (70) with screws.
Is fixed by fixing it to a predetermined position of a mount (not shown). Similarly, the support units (54) and (58) are also fixed to predetermined positions on a frame (not shown).

Next, a stator structure and a rotor structure of a motor (70) suitable for a linear motion table will be briefly described with reference to FIGS. 5 and 6. FIG. 5 shows the cross-sectional shape of the stator and the coil structure. The stator (84) is wound around an annular portion (85) formed of a thin steel plate, short stator poles (86) and stator poles (86) arranged at equal intervals on the inner circumference of the annular portion (85). It consists of a turned coil (87). The figure shows A, B
2 illustrates a two-phase driven motor of the stator (84)
The stator poles (86) of are circled numbers 1, 2, 4, 5, 7,
A first group of torque poles marked 8, 9, 10, 11 and 12 and driven in phase A, also 13, 1
4,15,16,17,18,19,21,22 and 24 are attached, and it is classified into the torque pole of the 2nd group driven by B phase, and also the sensor pole with the circled numbers other than the above. To be done.

Referring to FIG. 6, the rotor 72 is formed of a cylindrical core 88 and a high magnetic force permanent magnet such as samarium / cobalt alloy, and the polarities are alternately arranged on the outer peripheral surface of the cylindrical core 88. Rotor poles fixed and arranged differently (89)
And shaft (90). Then, the rotor (7
The rotation angle of 2) is detected by the sensor pole as a magnetic flux change. The motor having the above-described stator structure and rotor structure is characterized in that the position detection signal does not undergo rotation speed modulation of the rotor, and therefore highly accurate position control is possible. This motor (70) is disclosed in detail in Japanese Patent Application No. 171371.

Referring again to FIG. 4, the table 66 is configured to be movable in the left-right direction in the drawing by engaging a linear shaft (not shown) arranged in parallel with the ball screw 52. There is. The ball nut (62) is fitted into the fitting groove (68) of the table (66) by its flange (64) so as not to rotate. Therefore, when the motor (70) rotates and the ball screw (52) connected by the coupling (96) rotates, the ball nut (62) moves the table (66) left and right according to the rotating direction. ..

[0006]

In the conventional linear motion table, firstly, since the overall length is increased by the size of the motor (70) and the coupling (96), the movable distance of the table (66) and the device size. Has the disadvantage that the ratio of Second
In addition, there is a drawback that the ball screw (52) vibrates due to the spring component of the coupling (96) in the rotation direction, and abnormal noise is generated.
This spring component of the coupling (96) also causes the slider (66) to
Since it vibrates around the set position, it has a drawback that the high speed position control of the slider (66) cannot be performed. Third, after positioning the support units (54) and (58) first, the motor (70) must be further positioned to align the ball screw (52) and the rotor shaft (74) with each other. Not only the assembling work is complicated, but also when the shaft centers do not match, abnormal noise is generated and the bearings at various places are damaged. Fourth
In addition, since the ball screw (52) rotates, the ball screw (52) needs to be shielded. Fifth, an encoder for detecting the absolute position of the table is indispensable, and there is a problem that the entire length is further increased by the size of the encoder.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to downsize a linear motion table, reduce noise, control at high speed, reduce the number of parts and facilitate the assembly process.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a stator having a sensor pole for detecting a rotation angle of a rotor is arranged in a table of a linear motion table, and a rotor screw-coupled with a ball screw is further provided in the stator. The main feature is the coaxial arrangement.

[0009]

Since the motor structure is built in the table, the table can move the entire length of the apparatus, and since the rotor shaft also serves as the ball screw, the coincidence of the axes is simplified. Further, since the movable part is limited to the table, the reliability is improved. Further, since the table is directly controlled without using the ball screw, it is possible to control the position of the table with high speed and high accuracy. Furthermore, an encoder for detecting the absolute position of the table becomes unnecessary.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. 1 is a horizontal cross-sectional view of the essential part of the embodiment, and FIG. 2 is a vertical cross-sectional view taken along the line AA of FIG. Figure 1
As shown in FIG. 2 and FIG. 2, the linear motion table with a built-in motor of the present invention has a ball screw (10), a ball screw (1
Rotor (20) screw-coupled to (0), linear rail (14) arranged in parallel with the ball screw (10), this linear rail (14)
A table (30) that engages with and moves in the left-right direction in the drawing, a stator (40) arranged in a fitting hole (32) formed in the table (30), and the stator (40) with the rotor (20). A ring-shaped 2 that is coaxially arranged with the rotor (20) and rotatably supports the rotor (20).
It consists of two bearings (44).

The contact surfaces (47) and (48) of the inner ring (45) and the outer ring (46) of the bearing (44) are used to convert the rotational force of the rotor (20) into a lateral force in the drawing. (Ball screw (1
It is formed at about 45 degrees with respect to (0)). This kind of bearing
(44) is called an angular contact bearing and has an advantage suitable for high speed rotation. In the present invention, as the bearing (44), a deep groove bearing can be used in addition to the angular contact bearing. In addition, the inner peripheral surface of the inner ring (45) and the outer peripheral surface of the outer ring (46) of the bearing (44) of the embodiment are threaded, but when adopting press fitting, adhesion or other means, the bearing ( It is not necessary to screw the inner peripheral surface of the inner ring (45) of 44) and the outer peripheral surface of the outer ring (46).

In the illustrated embodiment in which the ball screw nut (22) is formed at the axial center position of the main body of the rotor (20), the rotor (20) is made of a magnetic material and is made of an iron-based material having a good screw connection. used. However, it is possible to form the ball screw nut (22) and the rotor (20) main body separately, and in that case, the rotor (20) main body and the ball screw nut (22) should be made of suitable materials. Can be used. At both ends of the rotor (20), screw portions (24) are formed which are screwed to the inner peripheral surface of the inner ring (45) of the bearing (44). The rotor pole (26) is made of a high magnetic force permanent magnet such as samarium / cobalt alloy, and is arranged and fixed to the outer peripheral surface of the rotor (20) so that the polarities are alternately different.

The table (30) is provided with a guide (36) which engages with the stator fitting hole (32) and the linear rail (14), and the outer ring of the bearing (44) is provided at the terminal end of the stator fitting hole (32). A screw part (34) is formed to be screwed to the outer peripheral surface of the (46). Although FIG. 2 illustrates a stator and rotor structure including 16 stator poles and 12 rotor poles, the number of stator poles and rotor poles is 4: 3.
Alternatively, if it is 4: 5, any number can be selected.
The present invention employs the stator and rotor structure described in the section of the conventional example. Referring again to FIG. 5, the circled number 3,
A signal of about 100 KHZ is supplied to the terminal C-C of the bridge circuit composed of sensor poles 6, 20 and 23, and a rotation angle signal in which the π / 2 phase is shifted is obtained at the terminals D and D. Be done. Then, based on the phases of the two rotation angle signals of the terminals D, D, addition or subtraction of one rotation angle signal is determined, and the position of the table (30) is detected. As a result, according to the present invention, it is not necessary to separately provide an encoder.

Next, an example of the assembling process of the embodiment will be described. In this embodiment, first, the stator is installed in the fitting hole (32) of the table (30).
(40) and the ring-shaped spacer (42) are placed and the table (3
0) is completed. Next, the inner ring (45) of the one bearing (44) is firmly coupled to the screw portion (24) of the rotor (20). This allows
The inner ring (45) of the bearing (44) is fixed to the rotor (20), and the bearing (44)
A structure is obtained in which the outer ring (46) of the motor freely rotates. Subsequently, the ball screw nut (22) of the rotor (20) was engaged with the ball screw (10), and the rotor (20) was further inserted into the space of the stator (40) and was first coupled to the rotor (20). Outer ring (46) of bearing (44)
Are screwed to the screw part (34) of the table (30). The inner ring (45) and outer ring (46) of the other bearing (44) are connected to the rotor.
The screw part (24) of the (20) and the screw part (34) of the stator (40) are screwed together to complete the process.

The linear motion table with a built-in motor of the present invention is a ball screw for the rotor (20) based on the rotation of the rotor (20).
The principle of operation is that the force in the (10) direction is transmitted to the table (30) via the angular contact bearing (44) and the table (30) moves.

FIG. 3 shows another embodiment of the present invention. In this embodiment, firstly, the ball screw nut (22) and the rotor (20) are separately formed of the optimum materials and fixed and integrated with each other. Secondly, the fixing of one bearing (44) At the table (3
(3) and the other bearing (44) are screwed together. Thirdly, in order to enable the insertion of the bearing (44) into the rotor (20), the rotor pole (26) is the rotor (2
It is different from the previous embodiment in that it is embedded in 0).

According to this embodiment, the ball screw nut (22)
Of course, the rotor and the rotor (20) can be easily machined with the optimum materials, and the advantage that the assembly process is easy,
Further, it has the advantages of reducing wind loss due to the rotor pole (26), and reducing vibration and noise.

Although the two embodiments characteristic of the present invention have been described above, the present invention is not limited to the embodiments, and the technique disclosed in the embodiments, for example, two types of ball screw nuts (22) each are disclosed. Structure, rotor pole (26) structure, bearing (44)
It is possible to implement it by arbitrarily combining the fixing structures of.

[0019]

As described above, the linear motion table with a built-in motor of the present invention cannot be downsized for the purpose, and the motor structure is provided in the table having a sufficient capacity to house the motor. Since it is built-in, the device is downsized, and a separate encoder is not required, so it is further downsized, and the table can move the entire length of the device. Further, since the rotor shaft and the ball screw are also used, the coincidence of the axis centers is simplified. Further, since the movable part is limited to the table, the reliability is improved. Further, since the table is directly controlled without using the ball screw, it is possible to control the position of the table with high speed and high accuracy. Furthermore, since the ball screw is fixed, the ball screw need not be shielded.

[0020]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a main part of an embodiment of the present invention.

FIG. 3 is a cross-sectional view of the essential parts of another embodiment of the present invention.

FIG. 4 is a cross-sectional view of a conventional linear motion table.

FIG. 5 is a sectional view of a stator suitable for a linear motion table.

FIG. 6 is a sectional view of a rotor suitable for a linear motion table.

[Explanation of symbols]

 10 ball screw 14 linear rail 20 rotor 30 table 40 stator 44 bearing

Claims (6)

[Claims] 1. A rotor having a ball screw, a ball screw nut screw-coupled to the ball screw, a linear rail arranged in parallel with the ball screw, a table engaging with the linear rail and having a stator fitting hole formed therein, A motor built-in linear motion table including a stator and two ring-shaped bearings that coaxially arrange the stator and the rotor and rotatably support the rotor. 2. A torque pole and a sensor pole for detecting a rotor position are arranged on the stator in a predetermined arrangement,
Π that is obtained from this sensor pole with equal spacing
The linear motion table with a built-in motor according to claim 1, wherein the position of the table is detected from a rotation angle signal having a phase difference of / 2. 3. The linear motion table with a built-in motor according to claim 1, wherein the rotor and the ball screw nut are integrated. 4. The motorized linear motion table according to claim 1, wherein the rotor and the ball screw nut are provided separately. 5. A linear motion table with a built-in motor according to claim 1, wherein a step portion of the bearing stopper is formed at a position where the rotor and the stator fitting holes of the table face each other. 6. A linear motion table with a built-in motor according to claim 1, wherein a permanent magnet is embedded in the cylindrical surface of said rotor.