JP2000257604A - Linear motion driving gear and linear motion driving method using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To handle even a workpiece of large weight and realize remarkable reduction of a cost, by integrally forming a cylinder with a piston rod linearly moving by supply of a fluid in a hollow motor. SOLUTION: This linear motion driving gear, constituted by cylinders 2, 2 with a piston rod 24 linearly moving by supply of air and a hollow motor 11 turning a hollow rotary shaft 8 by carrying a current in a stator 7 to make a ball screw 4 linearly move, is provided with a table 31 held linear motion operable by a guide means comprising the piston 24 and the ball screw 4 by integrally fixing the cylinders 2, 2 and the hollow motor 1 and an encoder 13 detecting a linear motion amount of this table 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear drive device and a linear drive method using the same. For example, an article conveyed on a production line or a distribution line can be stopped at a predetermined work place and moved up and down. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid linear motion technology driven by versatile electricity and air pressure for moving.

[0002]

2. Description of the Related Art Conventionally, a pneumatic cylinder that generates a large force has been used in lifting and lowering a heavy workpiece and in a slide mechanism for moving the workpiece horizontally. With such a pneumatic cylinder, it is difficult to accurately control the movement of the piston rod. From this, Tokuhei 4
As shown in the "suspension device" of JP-A-57595,
Motor drive control and air pressure supply control to the air cylinder by maintaining the balance with air pressure on the lifting unit equipped with a motor driven ball screw and switching the air pressure according to the weight of the suspended article The technique of performing arbitrary stop positioning by performing both of them is known.

According to the "hollow motor with ball screw" disclosed in JP-A-63-154038, a ball nut is fixed to a rotor, and a ball screw screwed to the ball nut is used as an output shaft of the motor. Therefore, a hollow motor has been proposed in which a ball screw is inserted into and taken out of the motor as the motor rotates, and is widely used at present because a direct-acting mechanism can be omitted and a compact and lightweight structure can be achieved.

[0004]

However, according to the "suspension device" disclosed in Japanese Patent Publication No. 57575/1992,
Since the method only deals with a change in the weight of a suspended work, it cannot be used as it is in a linear motion mechanism for lifting and lowering a heavy work or moving the work horizontally.

[0005] On the other hand, a work elevating device needs a guide mechanism for stably guiding the work in the vertical direction without play, and a horizontal slide mechanism needs to be provided with a similar guide mechanism. Therefore, by adding such a work guide mechanism to the above-mentioned suspension device, there is no possibility that a heavy-weight work can be lifted or lowered and a linear motion device that moves the work horizontally can not be implemented.

However, when such a work guide mechanism is added to, for example, the above-mentioned suspension device to constitute an elevating device or a slide device, it naturally leads to an increase in cost. In addition, the configuration becomes complicated.

[0007] Accordingly, the present invention has been made in view of the above problems, and by integrating a hollow motor having a linear motion mechanism with a cylinder in which a piston rod linearly moves by fluid supply, the weight of the hollow motor is reduced. It is an object of the present invention to provide a linear drive device capable of handling a large work, realizing a significant cost reduction, and having a simple structure, and a linear drive method using the same.

[0008]

According to the present invention, in order to solve the above-mentioned problems and achieve the object, according to the present invention, a cylinder in which a piston rod moves linearly by supplying a fluid, and a through hole at a rotation center of a rotor are provided. A hollow motor that engages a rod to be inserted with a rotation / linear motion converter fixed to the rotor, rotates the rotor by energizing the stator or the rotor, and linearly moves the rod. Wherein the cylinder and the hollow motor are integrally fixed to be held linearly by the guide means comprising the piston rod and the rod. It is characterized by comprising a moving body and a detecting means for detecting a linear movement amount of the moving body.

Further, the cylinder and the hollow motor are integrally fixed in parallel in a linear motion direction, and the moving body is fixed to an end of the piston rod and an end of the rod. I have.

In addition, a pair of cylinders are integrally fixed to the hollow motor in parallel in a linear motion direction, and the moving body is connected to a pair of ends of the piston rod and ends of the rod. It is characterized by being fixed to.

In addition, the cylinder and the hollow motor are integrally fixed in series in the direction of linear movement, and the end of the piston rod or the end of the rod is used as the moving body, and the cylinder is directly rotated. It is characterized by being movable.

The cylinder operates by supplying and exhausting a predetermined air pressure, the hollow motor is a servomotor provided with a rotor on the rotor, and a rotating magnetic field is applied to the stator. A ball screw having a ball body screwed into the screw lead groove,
The detection means is an encoder fixed to the rotor.

In a linear drive method using a linear drive device, a fluid control means for supplying the fluid, an energization control means for energization, the fluid control means, and the energization control means And connected to the detection means,
A main control unit for performing predetermined synchronous control of the fluid supply, the energization, and the positioning; performing a fluid control for the fluid supply, an energization control for the energization, and the positioning; It is characterized by performing linear motion control while receiving a load or a load applied to the body, or both a load and a load.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a main part of a parallel-type linear drive device. FIG. 2 is a view taken along line XX of FIG.
1 and 2, a hollow motor 1 is provided at the center of a common base plate 30, and a cylinder 2 having a piston rod 24 linearly moved by the supply of air or oil fluid to the left and right with the hollow motor 1 interposed therebetween. Is provided.

The hollow motor 1 includes a motor housing 3 and
A bearing 6 such as an angular contact bearing, which is fixed in the position shown in the drawing and is fixed to prevent play in the thrust direction, a hollow rotary shaft 8 rotatably supported by the bearing 6, and a hollow rotary shaft A multipolar magnetized rotor magnet 9 fixed to the outer peripheral surface of the shaft 8, and a motor housing 3 opposed to the rotor magnet 9.
And a stator 7 fixed inside the
By supplying power of a predetermined waveform to the stator 7 via the motor terminal 12, a rotating magnetic field is generated in the stator 7, and the rotor magnet 9 is magnetically attracted by the rotating magnetic field to move the hollow rotating shaft 8 in a predetermined direction. It is configured to be rotationally driven.

A rotary encoder 13 is fixed below the hollow rotary shaft 8, and an encoder terminal 1 is provided.
4 through the motor control unit 101.
To enable predetermined control of the hollow motor 1 based on the amount of rotation. Instead of the rotary encoder 13, a linear encoder may be fixed along a linear motion direction described later, and the amount of movement may be directly detected and input to the motor control unit 101.

A through hole is formed in the center of rotation of the hollow rotary shaft 8 in the longitudinal direction, and a ball screw 4 as a rod is provided so as to pass vertically through the through hole. A ball groove portion 4a as shown in the figure is formed on the outer peripheral surface of the ball screw 4, and a rotary-to-linear motion converting portion built in so as to circulate and move a large number of balls partially inserted into the ball groove portion 4a. Is provided so as to be engaged. The ball nut 5 is integrally formed with a flange portion as shown, and is fixed to the upper end wall surface of the hollow rotary shaft 8 via the flange portion. The upper end of the ball screw 4 is fixed to a bottom surface of a table 31 serving as a moving base via a fixing member 32, and the lower end side of the ball screw 4 is a ball screw bearing 11 configured to guide the crest of the ball groove 4a. It is movably guided in the longitudinal direction to prevent backlash in the radial direction. When the movement distance is small and the backlash is not large, the ball screw bearing 11 may not be provided. Below the ball screw bearing 11, a ball screw 4
A hole 30a is formed in the base plate 30 so that the base plate 30 can be moved further downward from the state shown in FIG.

Next, the cylinder 2 includes a piston rod 24
Cylinder chamber 21 having an inner diameter portion for guiding a piston 22 fixed to the tip of the cylinder so as to be slidable in an airtight or liquid tight state.
, And a piston bearing 23 for slidably guiding the upper end side of the piston rod 24. The predetermined fluid is supplied through inlets 25 a and 25 b communicating with the cylinder chamber 21 and an exhaust port 27. By performing supply and exhaust, the internal pressure of the cylinder chamber is changed, thereby moving the piston rod 24 up and down.

The upper ends of these piston rods 24 are fixed to the bottom surface of the table 31.
Is moved in the direction of the arrow. Here, if the parallelism between the piston rod 24 and the ball screw 4 is not ensured, the locking occurs in an immovable state due to undulation, and it is needless to say that it is necessary to provide a degree of freedom to any of the table fixing portions. However, for this, a rubber bush, a universal bearing, or the like can be used. Further, pipes are provided at the inlet portions 25a and 25b, and are connected to a fluid control unit 102 that obtains air pressure from a pump device 103. The exhaust port 27 is provided with a silencer for reducing exhaust noise.

The above-described motor control unit 101 and fluid control unit 1
Reference numeral 02 is connected to the main control unit 100, and controls while synchronizing them.

In FIG. 2, when the hollow motor 1 is composed of a motor housing having a square side shape as shown in the figure, the hollow motor 1 is united as shown in the drawing with a cylinder 2 also having a substantially square side shape. As a result, the distance L between the centers of the piston rods 24 can be set to be small, and the configuration can be made smaller. Further, a dovetail groove 20a formed continuously along the longitudinal direction in the housing 20 of the cylinder 2 as shown in the figure.
Can be directly fixed to the device 300 using bolts and nuts. In this case, if the hollow motor and the cylinder can be fixed, the base 30
Is unnecessary, and further cost reduction is possible. Further, in FIG. 2, it is also possible to add three or four cylinders along each side of the four sides of the hollow motor. Alternatively, one cylinder may be provided.

FIG. 3 is a central sectional view showing a case where the cylinder and the hollow motor are integrally fixed in series in the direction of linear motion. In this drawing, the components already described are denoted by the same reference numerals, and description thereof will be omitted. The characteristic portion will be described. First, in addition to the above-described ball groove portion 4a, a ball screw 4 provided in the hollow motor 1 is provided. A V-groove portion 4b is formed along the longitudinal direction. The V-groove portion 4b intrudes into a protrusion provided on the rotation preventing member 19 fixed next to the ball nut 5, so that the ball screw 4 does not rotate. In this way, the ball screw 4 can be moved in and out in the direction of the arrow as the ball nut 5 rotates. 1 and 2, the upper end of the ball screw 4 does not rotate since it is fixed to the table 31.

On the other hand, on the opposite side of the ball screw 4, the piston rod 2 prepared as an integral part or a separate part is provided.
4 is fixed.

[0025] In the case where the fixing members are integrally fixed in series in the direction of linear movement as described above, it can be provided in a narrower space.

FIG. 4 is an air circuit diagram of the above fluid control unit. First, in FIG. 4 (a), after obtaining a predetermined air pressure from the air compressor 103, it is turned on and off by a valve 50, and the turned on air pressure is set to a pressure a in a pressure adjusting unit 51, and thereafter, a fat and oil component and moisture are removed. And passes through a branch pipe and enters a relief regulator 56. In addition, a pressure b, which is a pressure for advancing the cylinder, is provided in a pipe branched from the branch pipe.
And a precision pressure reducing valve 53 for setting the pressure c, which is a pressure for retracting the cylinder, to be driven based on a control signal from the main control unit 100. The three-way solenoid valve 55 is connected to the c side and the b side, and the outlet of the three-way solenoid valve 55 is connected to the pilot air port PA of the relief regulator 56. From this relief regulator 56, piping connected to the inlets 25a and 25b of the cylinder 2 described in FIG. 1 or the inlet 25c of the cylinder described in FIG. 3 extends.

In the pneumatic circuit configuration described above, when the system is started from the standby state shown in FIGS. 1 and 3, the pressure reaching the relief regulator 56 while maintaining the pressure a is the same pressure.
Pass through and enter the entrances 25a, 25b, 25c. Also,
The air pressure that has passed through the precision pressure reducing valve 54 and has become the pressure b is 3
When the solenoid valve switch b side of the directional solenoid valve 55 is turned on, the pilot air port PA of the relief regulator 56 is entered. By the work of this pilot airport PA,
The output of the relief regulator 56 changes to the pressure b,
The thrust is input to the cylinder chamber, for example, to move the table 31 upward. Here, the basic role of the relief regulator is to set the outlet side to the same pressure as the input pressure to the pilot air port PA and return the air released when the piston rod 24 retreats to the output side of the relief regulator. , Which can be released.

The pressure c can be set by turning on the solenoid valve switch c side of the three-way solenoid valve 55.
Since the pressure b is related, if the hollow motor 1 is driven in reverse rotation, the air is exhausted from the relief regulator while moving in a compressed state.

By repeating the above operation and constantly monitoring the amount of movement of the ball screw 4 by the encoder 13 of the hollow motor 1, it is possible to stop the energization of the hollow motor when the table 31 moves to a desired position. Alternatively, the table 31 is positioned by forcibly stopping the rotation of the ball screw by an electromagnetic brake (not shown).

Next, in FIG. 4 (b), the components already described in FIG. 4 (a) are denoted by the same reference numerals, and the description thereof will be omitted. Are connected in parallel, so that the pressure is gradually decreased in a stepwise manner, and then the pressure is input to the three-way solenoid valve 55.

According to the above configuration, when a work is pressed into a predetermined hole or an extremely heavy work is lifted upward, a predetermined high pressure can be introduced into the cylinder. With such a thrust, it becomes possible to perform a linear motion that is impossible at all. Further, when descending, the pressure is switched so as to gradually introduce a small pressure into the cylinder, so that it is possible to maintain balance and smoothly descend.

As described above, the hollow rotary shaft rotating with the ball nut exerts a thrust by sharing between the ball screw and the piston rod as the actuators for a single load generated when the workpiece is lifted or moved. The hollow motor is controlled to stop at the target slide position based on the rotation amount detection information. Further, by using a hollow motor, the ball screw forms a linear motion guide, so that the space efficiency can be improved accordingly. Further, by adopting a housing shape as shown in FIG. 2, the number of cylinders can be arbitrarily increased / decreased, so that the unit can be divided into units or standard units, so that division and replacement are facilitated. Also, the power can be changed easily. Further, when used as a slide unit or a power unit, a dedicated fixing member for vertically and horizontally disposed is not required.

The series type shown in FIG. 3 has a pneumatic cylinder and a motor arranged in series and connects a piston rod and a ball screw on the motor side, so that the number of hollow motors is one. Since the number can be further increased in the axial direction, it is particularly suitable for environments where lateral space cannot be used. On the other hand, the parallel type shown in FIG. 1 can increase or decrease the number of pneumatic cylinders as described above, and is particularly suitable for an environment where vertical space cannot be used.

In the vertical arrangement (elevation), a static load and an inertial force (during acceleration / deceleration) of a load object are applied. In the horizontal arrangement (horizontal), the frictional force and the inertial force (during acceleration / deceleration) of the load object are applied. However, it can be flexibly handled by controlling the air pressure and the energization as described above.

The power of the pneumatic cylinder should be approximately equal to or less than the load (vertical) and inertial force (horizontal) of the object to be loaded. Thus, the motor capacity can be reduced by reducing the motor power. In addition, since the motor is driven under a condition close to no load, a movement with mobility can be performed. As the fine adjustment (control) method, the detection information (position,
By controlling the motor power (position, speed, torque) based on the speed and the torque of the servomotor, and performing the stop operation and the movement operation of the entire unit, fine control can be performed for a large load. As a result, it is possible to improve stopping accuracy (position and time) and freely set a moving time, etc., as compared with the case of using only the air cylinder. Another fine-tuning (control) method is to control the motor power (position, speed, torque) based on the weight, size, and type of the load object, and select either the stop operation pattern or the movement operation pattern for the entire unit. By doing so, it becomes possible to deal with various load objects only by software change of the control program, and in this case, centralized control becomes easier.

The pneumatic cylinder and the hollow motor as the motor power sharing type share the thrust for the load (vertical) and inertial force (horizontal) of the load object, and perform fine adjustment (control) only with the motor power. By performing the fine adjustment (control), the load on the pneumatic cylinder can be reduced, but the mobility decreases. The mechanical synchronization at this time is such that the piston rod and the end of the motor ball screw are mechanically connected and restrained, and slide in parallel. The electric synchronization synchronizes the electromagnetic valve opening / closing operation at the start and stop of the movement with the motor ON / OFF operation. Then, as a stopping method, after a brake is applied by an electromagnetic brake or the like, the electromagnetic lock is applied and the pneumatic valve is closed. By using a servomotor as a hollow motor for motor control, the NC control can be used with a high degree of freedom.

The balance equation is: W = R + NRi (i = i
The meaning of the second cylinder), for example, parallel configuration ...
W = R + 2Ri, serial configuration ... W = R + Ri.
Here, W = work load, R = ball screw thrust, R
i = pneumatic cylinder thrust, N = pneumatic cylinder number (N, i = the i-th cylinder).

The thrust generating principle of the hollow motor is as follows. If the thrust of R is the motor torque Υ, a thrust of R = Υη / 2π is generated. Here, T = hollow motor torque, η = lead of a ball screw (feed screw), π = screw efficiency, and the feed screw is not limited to a ball screw but includes a slide screw, and for example, there is another trapezoidal screw.

On the other hand, the principle of air thrust generation is based on the air thrust Ri =
K × A × P, where K = proportional constant, A = pressure receiving area of the pneumatic cylinder P = set pressure

In the case of the serial configuration, the ball screw spline uses a spline nut as a detent of the shaft, and can rotate the ball screw nut on the spot by a hollow motor to obtain a thrust without rotating the ball screw.

The right half of the ball screw spline shaft is the piston rod of the cylinder, so that the total thrust of the thrust of the ball screw and the air thrust can be obtained as a whole, thereby producing high thrust in a small space.

By providing a large number of these ball screw splines and piston rods integrally, a large number of hollow motors and cylinders may be connected serially.

As described above, according to the present invention,
By integrating a hollow motor equipped with a linear motion mechanism and a cylinder whose piston rod moves linearly by supplying fluid, it is possible to handle heavy workpieces, realize significant cost reductions, and have a simple configuration. A linear drive device and a linear drive method using the same can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a parallel-type linear drive device.

FIG. 2 is a view taken along line XX of FIG. 1;

FIG. 3 is a center cross-sectional view of a series-type linear drive device.

FIG. 4 is a configuration diagram of an air circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hollow motor 2 Cylinder 3 Motor housing 4 Ball screw 5 Ball nut 6 Bearing 7 Stator 8 Hollow rotating shaft 9 Rotor 13 Encoder 19 Detent member 20 Housing 21 Cylinder chamber 22 Piston 24 Piston rod 31 Table 100 Main control unit 101 Motor control unit 102 Fluid control unit

Claims (6)

[Claims] 1. A cylinder in which a piston rod moves linearly by supplying a fluid, and a rod inserted into a through-hole at the center of rotation of a rotor are engaged with a rotation / linear motion converter fixed to the rotor. A hollow motor that rotates the rotor by energizing a stator or a rotor to linearly move the rod body, wherein the cylinder and the hollow motor are integrally formed. It is characterized by comprising a moving body which is fixed by being fixed so as to be able to move linearly by the guide means comprising the piston rod and the rod, and a detecting means which detects a linear movement amount of the moving body. Linear drive. 2. The method according to claim 1, wherein the cylinder and the hollow motor are integrally fixed in parallel in a linear motion direction, and the moving body is fixed to an end of the piston rod and an end of the rod. The linear drive device according to claim 1. 3. A pair of the cylinders is integrally fixed to the hollow motor in parallel in a linear motion direction.
The linear drive device according to claim 2, wherein the movable body is fixed to a pair of ends of the piston rod and an end of the rod body. 4. The cylinder and the hollow motor are integrally fixed in series in the direction of linear motion, and the end of the piston rod or the end of the rod is used as the moving body to prevent the cylinder from rotating. The linear drive device according to claim 1, wherein the linear drive device is movable. 5. The cylinder operates by supplying and exhausting a predetermined air pressure, the hollow motor is a servomotor provided with a rotor in the rotor, and applies a rotating magnetic field to a stator. A ball screw having a ball body screwed into the screw lead groove, and the detecting means is an encoder fixed to the rotor. The linear drive device according to any one of claims 1 to 4, wherein: 6. A linear drive method using the linear drive device according to claim 1, wherein the fluid control means for supplying the fluid, the current control means for energizing, and the fluid control. Means for controlling the fluid supply, the energization and the predetermined synchronous control of the positioning by being connected to the means, the energization control means and the detection means, the fluid for fluid supply The linear drive device is characterized in that it performs control, the energization and energization control for the positioning, and performs linear motion control while receiving a load or weight applied to the moving body, or both of the load and the load. Linear drive method.