JP3044196B2 - Balance mechanism of driven body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved balance mechanism for a driven body.

[0002]

2. Description of the Related Art As a balance mechanism of a driven body, a counterbalance system using a weight, a system using a hydraulic cylinder or a pneumatic cylinder, and the like are known.

FIG. 5 is a conceptual diagram showing a balance mechanism of a counter balance system. In FIG. 5, reference numeral 101 denotes a machine having a driven body 102 that moves vertically against gravity, for example, a machine tool, and is driven by a feed screw 104 that is rotationally driven by a driving mechanism 103 such as a motor. The body 102 can be fed vertically.

The balance mechanism 105 includes a counterweight 106 formed to have the same weight as the driven body 102, flexible connecting means 107 such as a cable connecting the driven body 102 and the counterweight 106, and a flexible connection means 107. Gravitational load F1 acting on the driven body 102 is offset by a gravitational load F2 acting on the counterweight 106. I have to.

Accordingly, the gravitational load acting on the driven body 102 can be virtually eliminated, but the inertia mass to be driven is twice as large as that of the case where only the driven body 102 is used. There is a problem that a large driving force is required when the driving body 102 is accelerated or decelerated.

This technique is effective only when the driven body 102 is held at a fixed position for a long time to perform work. For example, when the driven body 102 is moved up and down frequently, for example,
It is not suitable for vertical movement of the machining head of a machine tool. If the pulley is used, the gravitational load of the driven body 102 can be offset by the counterweight 106 which is lighter than the driven body 102, but the movement amount of the counterweight 106 increases in proportion to the reduction in the weight of the counterweight 106. As a result, the energy consumption remains the same and only helps to reduce the total weight.

FIG. 6 is a conceptual diagram showing a hydraulic cylinder type balance mechanism. Machine 101 and driven body 10
2, the configuration of the drive mechanism 103 and the feed screw 104 is the same as that of FIG.

The balance mechanism 110 includes a hydraulic cylinder (hydraulic cylinder or hydraulic cylinder) 111 connected to the driven body 102 directly or via a connecting means, and a pressure source 112 for supplying oil or water to the hydraulic cylinder 111. , And a pressure adjusting means 113 provided between the hydraulic cylinder 111 and the pressure source 112.

The pressure of the oil or water supplied from the pressure source 112 to the hydraulic cylinder 111 is such that the force acting on the piston of the hydraulic cylinder 111 cancels the gravitational load F1 of the driven body 102 by the pressure adjusting means 113. Excess oil or water which is adjusted to a value P1 to be the force F2 and supplied from the pressure source 112 to the pressure adjusting means 113 is discharged to the drain 114.
Is returned to the tank 115 on the pressure source 112 side.

If the hydraulic cylinder type balance mechanism 110 is used, the pressure in the hydraulic cylinder 111 can be increased to a large value such as 5 MPa to 20 MPa, so that the diameter of the hydraulic cylinder 111 can be reduced. As a result, it is possible to achieve a configuration that is smaller as a whole as compared with the balance mechanism 105 of the counter balance system.

However, the frictional resistance acting between the piston of the hydraulic cylinder 111 and the cylinder outer cylinder causes the driven body 10
In addition to interfering with the operation of step 2, the hydraulic cylinder 111
The stick-slip phenomenon occurs due to the difference between the dynamic friction resistance and the static friction resistance acting between the piston and the cylinder outer cylinder, and the feeding operation becomes unstable.

When the driven body 102 is fed at a high speed, the pressure adjustment by the pressure adjusting means 113 may not be in time for the operation of the piston rod, and the hydraulic cylinder which should cancel the gravitational load may be used. On the contrary, there is a case where the 111 acts as a disturbance load in the reverse feed direction of the driven body 102.

Further, a hydraulic cylinder 111, a pressure source 11
(2) Since additional components such as the pressure adjusting means 113 are required, the manufacturing cost of the machine 101 is also adversely affected.

FIG. 7 is a conceptual diagram showing a pneumatic cylinder type balance mechanism. Machine 101 and driven body 10
2, the configuration relating to the drive mechanism 103 and the feed screw 104 is the same as that in FIGS.

The balance mechanism 116 is a pneumatic cylinder 1
17, flexible connecting means 118 such as a cable connecting the driven body 102 and the piston of the pneumatic cylinder 117,
And pulleys 108 and 109 for slidably supporting the flexible connecting means 118 and distributing the flexible connecting means 118 to both sides of the machine 101, and the gravitational load F acting on the driven body 102.
1 is canceled by the force F2 of the piston in the pneumatic cylinder 117.

A pressure source 120 is connected to the pneumatic cylinder 117 via a pressure adjusting means 119 as in the case of the hydraulic cylinder type balance mechanism shown in FIG. 6, but the pressure source 120 in this case is An example is an air compressor. The pressure of the air supplied from the pressure source 120 to the pneumatic cylinder 117 is a value such that the force acting on the piston of the pneumatic cylinder 117 becomes a force F2 for canceling the gravitational load F1 of the driven body 102 by the pressure adjusting means 119. The excess air adjusted to P1 and supplied from the pressure source 120 to the pressure adjusting means 119 is discharged to the outside via the drain 121.

Pneumatic cylinder type balance mechanism 116
In the case of, since the compression ratio of the air serving as the pressurizing means is significantly higher than that of a liquid such as oil or water, even if the adjusting operation of the pressure adjusting means 119 is slightly delayed during the movement of the driven body 102, The pressure in the pneumatic cylinder 117, in other words, the magnitude of F2 does not fluctuate greatly, especially when the driven body 102 is fed at a relatively high speed, compared to the hydraulic cylinder type balance mechanism. , A better balance effect can be achieved.

However, the frictional resistance acting between the piston of the pneumatic cylinder 117 and the cylinder outer cylinder causes the driven body 1
02, when the driven body 102 is fed at a low speed or in small increments, a stick-slip phenomenon occurs due to frictional resistance between the piston and the cylinder outer cylinder, and the feeding operation becomes unstable. In this respect, the same problem as the hydraulic cylinder type balance mechanism remains.

On the other hand, if all the balance mechanisms are eliminated as in the machine 101 shown in FIG. 8, a disturbance load is generated due to an increase in the inertial mass of the driven object or a delay in the operation of the pressure adjusting means, and the frictional resistance and the like are reduced. Although it is possible to avoid the occurrence of the stick-slip phenomenon, in that case, the driven body 102 must be lifted against the gravity by the driving torque of the driving mechanism 103 itself or stopped at a fixed position. Must. As a result, the driving mechanism 103
However, the thrust that can be used to actually move the driven body 102 is only the amount obtained by subtracting the torque required for holding the driven body 102 from the total driving torque (when the driven body 102 is raised). , The actual driving force will decline. In addition, the driven body 102 cannot be held unless the torque corresponding to the weight of the driven body 102 is constantly generated on the drive mechanism 103 side. In some cases, the machining accuracy of a machine tool or the like may deteriorate, and power may be wasted.

[0020]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the disadvantages of the prior art and to offset the gravitational load caused by the weight of the driven body without increasing the inertial mass or resistance acting on the driven object. The object of the present invention is to provide a driven body balance mechanism capable of performing the following.

[0021]

According to the present invention, an outer peripheral portion or an inner peripheral portion of a driven body is horizontally supported by an air static pressure guide mechanism, and one of an upper end and a lower end of the driven body is surrounded. A hermetic chamber communicating with the air discharge path of the static air pressure guide mechanism is provided to support a gravitational load generated by the weight of the driven body by the pressure of air supplied from the air discharge path to the hermetic chamber. The above object has been achieved by a configuration characterized as described above. Since the outer peripheral portion or the inner peripheral portion of the driven body is horizontally supported by the air static pressure guide mechanism, no useless resistance acts when the driven body moves up and down. The pressure of air supplied from the air discharge passage of the air static pressure guide mechanism to the closed chamber acts on only one of the upper end and the lower end of the driven body, and supports the own weight of the driven body against gravity.

The whole structure can be simplified and miniaturized by sealing the hermetic chamber with air having a pressure higher than the pressure in the hermetic chamber discharged from the air discharge passage of the static air pressure guide mechanism.

When the driven body is fed by a screw mechanism built in the driven body, an air static pressure screw is used as a screw mechanism, and the driven body is moved horizontally by the air static pressure guide mechanism. Can support.

By providing a regulator for air discharge in the closed chamber, the air pressure in the closed chamber is maintained at a constant pressure, and the force acting on either the upper end or the lower end of the driven body is controlled by the weight of the driven body. Match the resulting gravitational load.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a machine 122 on which the balance mechanism of the present invention is mounted, for example, a machine tool. The configuration of the machine 122 itself is conceptually the same as the conventional one shown in FIGS.
A feed screw 124 rotated and driven by a motor 123 feeds the driven body 125 in the vertical direction. The driven body 125 is, for example, a processing head or the like in a machine tool, and vertically moves up and down along a column 126 called a column or the like.

On the upper and lower sides of one side of the column 126, two sliding support members 127 and 128 constituting an air static pressure guide mechanism are provided.
Is fixed and the driven body 12 is fitted therein.
5 is slidably mounted. The inner circumferential surfaces of the through holes of the sliding support members 127 and 128 through which the driven body 125 passes penetrate the circumferential groove 1 divided into three or more portions in the circumferential direction.
29, 130 are engraved, and the sliding support members 127, 128
13 with the same number of peripheral grooves 129 and 130
1, 132, respectively, and further, each of the pipelines 131, 1
An external line 133, 134 is connected to a pressure source 135 such as an air compressor. The pressure source 135 is a general industrial air compressor equipped with an air filter, a drain, a pressure regulator, an accumulator, and the like.

When the driven body 125 is formed by a complete columnar body, bosses and serrations are formed between the through holes of the sliding support members 127 and 128 and the driven body 125, or A guide rail for linear motion may be provided between the support 126 and the driven body 125 in some cases.

Between the outer peripheral surface of the driven body 125 and the inner peripheral surfaces of the through holes of the sliding support members 127 and 128 surrounding the driven body 125, gaps 136 and 137 having a certain size are formed.
The air supplied from the pressure source 135 is supplied to the external line 133,
The fluid flows into the circumferential grooves 129 and 130 on the inner peripheral surfaces of the sliding support members 127 and 128 via the pipes 134 and the conduits 131 and 132, and further flows into the outer peripheral surface of the driven body 125 and the sliding support members 127 and 128. It is discharged to the outside through gaps 136 and 137 between the peripheral surface. That is, the gaps 136 and 137
Are sliding support members 127 constituting an air static pressure guide mechanism,
128 is an air discharge path.

As a result of the gaps 136 and 137 acting as throttles, the internal pressure of the air forcedly supplied from the pressure source 135 rises in the circumferential grooves 129 and 130 and presses the driven body 125 radially inward. Since the circumferential grooves 129 and 130 are provided so as to surround the outer peripheral portion of the driven body 125, the sizes of the gaps 136 and 137 are equal at any position in the circumferential direction. The pressures of the opposing portions of 130 become equal, and the driven body 125
The driven body 125 is stabilized at a neutral position where the force for pressing the inner side in the radial direction is completely balanced, and does not contact the inner peripheral surfaces of the sliding support members 127 and 128 at all. The air volume and the gap 136,1 of the air supplied from the pressure source 135
When the air volume of the air discharged from 37 becomes equal, the increase in the pressure of the air in the circumferential grooves 129 and 130 stops, and the internal pressure is dynamically stabilized. Circumferential groove 12 in stable state
The air pressure P <b> 1 in 9, 130 can be adjusted by a pressure regulator on the pressure source 135 side. In other words, the pressure P1 increases if the amount of air to be sent is increased, and the pressure P1 decreases if the amount of air is reduced.

The principle of the centering action of the driven body 125 by the sliding support members 127 and 128 constituting the static air pressure guide mechanism is the same as that of a general radial static air pressure bearing.

Further, in the present embodiment, the driven body 1
25 so as to surround the lower end of the sliding support member 12.
A closed chamber 138 in the shape of a container with a bottom is fixedly provided integrally with the chamber 8. The vertical length of the sealed chamber 138 is determined in consideration of the movement stroke of the driven
Decide on a length that does not prevent the movement of 5. Further, a regulator 139 for discharging air is connected to the closed chamber 138 via an external conduit 140.

The closed chamber 138 is provided with a sliding support member 128.
Is connected to the circumferential groove 130 via a gap 137 on the lower surface side of the sliding support member 128, and the other portion is completely shut off from the outside. After entering the chamber 138, the air pressure in the closed chamber 138 is increased. In the sealed chamber 138, the air pressure acting on the entire outer peripheral surface of the driven body 125 is perfectly balanced, so that the driven body 125
No horizontal force acts on the Further, the air pressure acting on the lower end surface of the driven body 125 acts in a direction to push up the driven body 125.

Assuming that the air pressure in the closed chamber 138 is P and the area of the lower end surface of the driven body 125 is S, the driven body 12
5, the magnitude of the upward force F2 acting on the lower end face is F2 =
P · S. In addition, the closed chamber 138 is connected to the circumferential groove 13 through the gap 137 on the lower surface side of the sliding support member 128.
0, the air pressure P in the sealed chamber 138 can rise up to the aforementioned P1 (the air pressure in the circumferential groove 130) at the maximum. As a result, the driven body 1
25 that is the maximum value of the force that can be applied to the lower end face of F.25
max. is F2max. = P1 · S.
Since the value of 1 is determined, in order to support the gravitational load F1 caused by the weight of the driven body 125 by F2max., The bottom area S of the driven body 125 is designed so that the value of S is S ≧ F1 / P1. Must.

When F2> F1 and the balance cannot be maintained due to the large value of P, the closed chamber 1 is regulated by the regulator 139 (flow regulating valve) for discharging air.
What is necessary is just to reduce the air pressure P in 38 so that F2 = F1.

The driven member 125 is supported at a neutral position in a non-contact state by the sliding support members 127 and 128 constituting the aerostatic pressure guide mechanism, and the gravitational load F1 due to the own weight of the driven member 125 reduces the hermetic chamber 138. Since the upward force F2 (F2 = F1) generated by the internal air pressure is completely canceled, the driven body 125 can move up and down very smoothly by the feed operation by the rotation of the feed screw 124, and the motor 123 There is no needless load.
Unlike the hydraulic cylinder type balance mechanism and the pneumatic cylinder type balance mechanism, there is no change in frictional resistance between the piston and the cylinder outer cylinder, so that the stick-slip phenomenon does not occur. Also, there is no problem such as an increase in inertial mass as in the counterbalance method using a counterweight.

Although the internal volume of the sealed chamber 138 changes due to the vertical movement of the driven body 125, if the driven body 125 rises and the internal volume of the sealed chamber 138 increases, the air corresponding to this increases the pressure source. When the driven body 125 is lowered and the inner volume of the sealed chamber 138 is reduced, air corresponding to the amount is supplied to the external pipe 1.
Since the air is discharged to the outside via the pressure regulator 40 and the regulator 139, the air pressure in the sealed chamber 138 can be always maintained at the set value P, that is, a value that satisfies F1 = F2. Although there is no possibility that a certain degree of pressure fluctuation occurs in the course of the dynamic change, as already described in the section of the prior art, the compression ratio of the air serving as the pressurizing means is limited to oil or water. Is significantly larger than that of the liquid, even if there is some delay in replenishing or discharging air when the driven body 125 moves,
The change in F2 is insignificant and can be sufficiently tolerated.

Further, as in the embodiment shown in FIG. 2, the pressure source 135 is connected to the external line 140 instead of the regulator 139.
A separate pressure source 142 and pressure adjusting means 141 may be attached to supply air into the closed chamber 138. In this case, the value of F2 is made to match F1 by adjusting the pressure of the air input from the external conduit 140. Therefore, the lower sliding support member 128 constituting the static air pressure guide mechanism is exclusively used for the closed chamber 13 rather than a means for supplying air to the closed chamber 138.
8 acts as a means for sealing.

FIG. 3 shows an example in which the static air pressure guide mechanism constitutes a screw mechanism for feeding a driven body in a vertical direction.

In the machine 143 shown in FIG.
Motor 146 is a base for the machine 143.
A driven body 147 erected on the top 44 and vertically fed by a feed screw 145 is attached to a support 149 via a slider mechanism 148 so as to be vertically movable.

A gap 156 for forming a static air pressure guide mechanism is formed between the feed screw 145 and the female screw 150 on the driven body 147 side to be screwed with the feed screw 145. Inside, the pipes 151 and 152 are bored in the radial direction so as to communicate with the inner peripheral surface of the female screw 150. Further, a pressure source 155 composed of an air compressor or the like is connected to each of the pipes 151 and 152 via external pipes 153 and 154. The pressure source 155 is a normal industrial air compressor equipped with an air filter, a drain, a pressure regulator, an accumulator, and the like. In this embodiment, since the driven body 147 that moves relatively to the pressure source 155 and the pressure source 155 are connected by the external conduits 153 and 154,
It is necessary to use a flexible connection hose or the like as the external conduits 153 and 154.

The air supplied from the pressure source 155 flows into the gap 156 between the female screw 150 and the feed screw 145 through the external pipes 153 and 154 and the pipes 151 and 152, and further, the driven body 147 through the gap ends 156a and 156b on the upper and lower sides. That is, the gap ends 156a and 156b are air discharge paths in the static air pressure guide mechanism.

Air forcedly supplied from the pressure source 155 flows into the gap 156 between the female screw 150 and the feed screw 145 via the pipes 151 and 152, and the feed screw 145
As described above, since the feed screw 145 is erected on the base 144 via the motor 146, the feed screw 145 does not move in the radial direction, and as a result, the female screw 150 Side receives a force directed radially outward. Since the force is equal in any part of the inner peripheral surface of the female screw 150, the force for pushing the female screw 150 radially outward is perfectly balanced, and the size of the gap 156 is equal regardless of the circumferential position. Driven body 1 in neutral position
47 is stabilized, and does not contact the outer peripheral surface of the feed screw 145 at all. This structure is commonly referred to as an aerostatic screw.

Further, in the present embodiment, the driven body 1
A container-shaped closed chamber 157 with a bottom is fixedly integrated with the driven body 147 so as to surround the upper end of the 47. The length of the closed chamber 157 in the vertical direction is determined in consideration of the movement stroke of the driven body 147, that is, the amount of protrusion of the feed screw 145 above the driven body 147.
Determine the length so as not to hinder the movement of 47. Further, a regulator 159 for discharging air is connected to the sealed chamber 157 via an external conduit 158.

The closed chamber 157 communicates with the gap 156 via the gap end 156a on the upper surface side of the static air pressure guide mechanism, and is completely shut off from the outside at other portions. The discharged air enters the closed chamber 157 and increases the air pressure in the closed chamber 157. The air pressure in the sealed chamber 157 is P,
If the sectional area of the feed screw 145 is S, the closed chamber 1
The magnitude of the force F2 acting to lift the member 57 and the driven body 147 integrated with the member 57 upward is F2 = PS. Therefore, in order to balance the gravitational load F1 by the driven body 147 and the force F2 for lifting the driven body 147 upward to completely remove the influence of the gravitational load, the cross-sectional area of the feed screw 145 must be designed. However, there is the same limitation as the cross-sectional area S of the driven body 125 described in the above embodiment.

The difference between whether the feed screw mechanism and the aerostatic pressure guide mechanism are separately or integrally provided, and the fact that the driven body is suspended by mounting the motor and the feed screw above the machine. Although there is a difference in whether the motor and the feed screw are mounted on the lower side of the machine so as to support the driven body from below, the operation and the effect are described with reference to FIGS. 3 and FIG. 3 are substantially the same.

Of course, in any case, it is most desirable that the gravitational load F1 and the force F2 for supporting the gravitational load be completely matched. However, even if F1> F2, the load is not affected. Since the substantial gravitational load acting on the driving bodies 125 and 147 can be reduced from F1 to F1−F2, the reduction of the gravitational load has some meaning unless F2 = 0. This is the same for the embodiment described later.

FIG. 4 is a cross-sectional view schematically showing the structure of a vertical axis linear motion mechanism 1 according to an embodiment in which the balance mechanism of the present invention is mounted, divided by a plane including the center axis. The vertical axis linear motion mechanism 1 is attached to a base or the like of a machine tool, and is used for feeding a workpiece in a vertical direction.

As shown in FIG. 4, the vertical axis linear motion mechanism 1 has a table fixing means 3 for fixing the table 2, a rotation driving mechanism 4 provided therein, and a mounting mechanism for the rotation driving mechanism 4. These members are each formed of a cylindrical body or an annular body, as is apparent from FIG.

The rotary drive mechanism 4 is composed of a servomotor 4 'having a stator 6 on the inside and a rotor 7 on the outside. The cylindrical stator 6 located on the inside has a base 5 formed in an annular shape. At the position close to the circumference, several bolts 8
Is fixed integrally. Further, a cylindrical rotor 7 is rotatably mounted on the base 5 so as to surround an outer peripheral portion of the stator 6, and a male screw 9 is provided on an outer peripheral surface of the rotor 7 serving as a rotating portion. Is screwed to a female screw 10 provided on the inner peripheral surface of the table fixing means 3.

As described above, each of the stator 6, the rotor 7, and the table fixing means 3 is formed in a cylindrical shape, and all of them are arranged on concentric circles. A static pressure air bearing constituted by a nozzle 33 connected to a pipe 32 provided in the base 5 is provided on the sliding contact surface of the base 5.

The outer surface of the stator 6 has a coil 12
The rotor core 1 is integrally attached to the stator core 11 on which the rotor core 1 is wound.
3 and a magnet 14 are assembled, and an annular spacer 15 fitted to the upper end of the enlarged diameter portion forms a rotor 7.
It is fixed integrally to. Coil 12 and magnet 1
A static pressure air bearing composed of a nozzle 35 connected to a pipe 34 in the stator 6 connected to a pipe 32 provided in the base 5 is provided between the air bearing 4 and the pipe 4.

Further, an annular retainer 17 is integrally fixed to an upper end surface of the stator 6 with a plurality of bolts 18, and is connected to a conduit 36 through the inside of the retainer 17 and to a conduit 34.
The static pressure air bearing constituted by the nozzle 37 from the outside prohibits the axial movement of the rotor 7.

The upper end surface of the rotor 7 has a substantially T-shape,
Alternatively, a rotation detector mounting member 26 formed by a rotating body having a substantially T-shaped cross section is fixed so as to straddle the retainer 17 in the radial direction, and protrudes downward from the center of the rotation detector mounting member 26. An encoder disk 27a or the like, which is a component of the pulse coder 27, is fixed to the tip of the protrusion 26a via a bolt 28. Reference numeral 27b denotes a substrate on which a photocoupler or the like serving as a component of the pulse coder 27 is mounted, which is directly fixed to the center of the base 5.

As shown in FIG. 4, guide pins 19 fixed to the base 5 by bolts 20 are provided at three positions at a pitch of 120 ° in the circumferential direction at positions near the outer periphery of the base 5 formed in an annular shape. It is erected over. In addition, each guide pin 1
In the position of the outer peripheral portion of the table fixing means 3 corresponding to 9,
Each of the holes 21 is fitted with a guide pin 19 and regulates the moving direction of the table fixing means 3 with respect to the base 5.

A static pressure is provided between each guide pin 19 and the hole 21 by a nozzle 39 provided at the tip of a pipe 38 passing through the inside of the table fixing means 3 and penetrating the inner peripheral surface of the hole 21. Since the air bearing is provided, the outer peripheral surface of the guide pin 19 does not directly contact the inner peripheral surface of the hole 21. Air is supplied to the pipe 38 by a pipe 40 passing through the inside of the table 2 and a circumferential member formed by a sealing material 43 fitted in a circumferential groove formed in the lower end surface of the table 2. This is done via line 41. In other words, a plurality of conduits 38 are provided at a predetermined pitch on the same circumference of the table fixing means 3, and the upper end of each conduit 38 is connected to the peripheral conduit 41, and the peripheral conduit 41 Pipe 40 connecting from the side to
Supplied by air. An air compressor or the like serving as a pressure source is connected to the pipe 40 and the above-described pipe 32 via a flexible connection hose or the like serving as an external pipe.

The inside of the ridge of the female screw 10 in the table fixing means 3 has a pipe 42 penetrating to the surface thereof.
Are crossed and connected to a pipe 38 passing through the inside of the table fixing means 3 to supply air, similarly to the nozzle 39 described above. In other words, the female screw 10 of the table fixing means 3 and the male screw 9 of the rotor 7 constitute an aerostatic screw, and the male screw 9 of the rotor 7 and the female screw 10 of the table fixing means 3 are not directly contacted. Has become. The driven body in this embodiment is on the side of the table fixing means 3 and the table 2 which move up and down.

On the base 5, each guide pin 19
The through holes 22 are formed in three places at a pitch of 60 ° in the circumferential direction with respect to the standing position, and a bolt 23 for fixing the base is inserted therein. Holes 24 each having a diameter slightly larger than the head of the bolt 23 are formed in the outer peripheral portion of the table fixing means 3 corresponding to each through hole 22. A small-diameter through-hole 25 is formed corresponding to the position of the hole 24. Through hole 2
The diameter of 5 is large enough to insert a hexagon wrench that engages a hexagonal sunk hole formed in the head of the bolt 23.

The vertical axis linear motion mechanism 1 of this embodiment has a diameter 2
The vertical axis linear motion mechanism 1 can be used on a work table of another machine tool because the vertical axis linear motion mechanism 1 is designed to have a size of 20 mm / overall height of less than 100 mm. It is used when the first base 5 is fastened to a work table of a machine tool. Of course, if the work table of the machine tool is not provided with a screw hole compatible with the bolt 23, the bolt 23 is retracted into the hole 24 and the base 5 is directly fixed by the magnetic chuck of the work table. Alternatively, the base 5 can be fixed to the work table using other clamping means.
The rotation operation of the bolt 23 is performed by engaging a hexagon wrench inserted from the through hole 25 of the table 2 with a hexagonal sunk hole in the head of the bolt 23.

The hole 30 through which the bolt 29 for fixing the table 2 to the table fixing means 3 is inserted is formed by the hole 2
As in the case of 1, the tip of the bolt 29 penetrated at three positions at a pitch of 120 ° in the circumferential direction at a position close to the outer periphery of the disk-shaped table 2 and passed through each hole 30 Are screwed into female screws 31 provided on the table fixing means 3 to fix the table 2 to the table fixing means 3.

With the above configuration, the pipeline 40 and the pipeline 3
2 is supplied with air from a pressure source such as an air compressor, and a current is applied to the coil 12 to excite the servomotor 4 '. When the rotor 7 rotates around the stator 6 fixed to the base 5, the rotor 7 rotates. Rotation is blocked by the pin 19, and the cylindrical table fixing means 3 screwed with the male screw 9 of the rotor 7 via the female screw 10 on the inner peripheral surface moves up and down,
The table 2 is fed vertically.

As described above, a part of the air supplied to the pipe 40 is blown out between the female screw 10 and the male screw 9 through the pipes 38 and 42 to form an air static pressure guide mechanism. Therefore, similarly to the embodiment shown in FIG. 3, the female screw 10 and the male screw 9 function as an air static pressure screw as a whole.

Then, the air that has escaped upward through the space between the female screw 10 and the male screw 9 enters the hermetically sealed chamber formed by the container-shaped table 2 with the bottom.
Acts as a force F2 in the direction of pushing up the lower surface of.
In order to support all of the gravitational load F1 generated by the weight of the driven table 2 and the table fixing means 3 by its own weight, the air pressure in the table 2 is P, and the area of the lower surface of the table 2 is S. In this case, it is necessary to set S = F1 / P, as in the above embodiments. Needless to say, if a through-hole is formed at an appropriate position on the peripheral surface of the table 2 and a regulator for discharging air as described with reference to FIG. 1 or FIG. 3 is provided, the value of the pressure P in the table 2 serving as a closed chamber Can be arbitrarily adjusted within the range of the maximum output P1 of the pressure source, so that the maximum output of the pressure source may exceed the value of P in the above equation. In the case of the vertical axis linear motion mechanism 1, since the table 2 itself is a closed chamber, the pressure acting surface S can be made large as a whole, and even if the output of the pressure source is small, the table 2 and the table fixing means are used. It is easy to support all of the gravitational load F1 generated by the own weight of 3 (driven body) by air pressure.

In the example of FIG. 4, the complete thread of the male screw 9 is 4
Since the pitch and the completely threaded portion of the female screw 10 are two pitches, the entire thread can be moved up and down by about two pitches by about 20 mm. Of course, it is possible to increase the feed amount in the vertical direction by increasing the pitch number of the screws by forming the rotor 7 and the table fixing means 3 to be longer in the vertical direction, but the total height is kept at the same ratio with the increase in the feed amount. There is a problem of increase, and as long as high-precision positioning is aimed at, a movement limit of the table fixing means 3 of about 20 mm is sufficient.

Further, according to this embodiment, since the diameter of the male screw 9 serving as the feed screw is increased to a level comparable to the outer peripheral portion of the table 2, the fluctuation of the table 2 in the horizontal plane is very small. Less. For example, male screw 9 and female screw 1
When a constant moment M is applied between the table 2 and the axis 2 and the displacement in the axial direction is amm, in this embodiment, the right end of the table 2 is pressed against the base 5 and the table 2 is pressed.
Is raised by a force that applies a moment M to the left end of the table 2, the height difference between the right end of the table 2 and the left end of the table 2 is at most about amm. However, if the outer diameter of the male screw 9 is の of that of the embodiment, that is, の of the diameter of the table 2, the rattling generated in the screw portion is at least as large as that of the male screw 9. The signal is amplified to about twice in proportion to the outer diameter ratio of the table 2 and becomes 2 amm at the end of the table 2. Actually, the diameter of the conventional feed screw is not such as 1/2 of the diameter of the table 2 and is much smaller than that, so that the diameter of the table 2 of the present embodiment is smaller than that of the related art. The stability is outstanding.

A gap corresponding to the air gap of the hydrostatic air bearing is formed between the guide pin 19 and the hole 21 of the table fixing means 3. Will occur. If the displacement when a certain force F is applied between the guide pin 19 and the hole 21 is bmm and the distance from the center of the base 5 to the outermost guide pin 19 is r, θ is set around the axis. If rattling occurs, the guide pins 19 are moved from the center of the base 5.
When the distance to the axis is r / 2, it means that 2θ rattling occurs around the axis under the same condition. Regarding the displacement around the axis, the standing position of the guide pin 19 is the center of the base 5. The greater the distance from, the more advantageous.

Further, in this embodiment, each element constituting the rotary drive mechanism 4, that is, the servo motor 4 '
The stator 6 and the rotor 7 are arranged concentrically inside the table fixing means 3 made of a hollow cylindrical body, and the guide rod 19 which is a movement direction restricting means also serving as a detent for the table fixing means 3 is provided on the table. Since it is arranged inside the fixing means 3, the vertical axis linear motion mechanism 1
The vertical axis linear motion mechanism 1 itself is mounted on a table of another machine tool, and is used as a feed mechanism dedicated to precise positioning of a workpiece. You can also.

Of course, if necessary, it is also possible to dispose a magnetic chuck, a clamp mechanism or the like as in the prior art on the table 2 to fix the workpiece.

As described above, as an embodiment of the vertical axis linear motion mechanism, the rotor 7 is provided outside the stator 6, and the female 7 is provided on the inner peripheral surface of the table fixing means 3 with the male screw 9 provided on the outer peripheral surface of the rotor 7. The example in which the table 2 is moved up and down by feeding the screws 10 has been described. However, a cylindrical rotor is provided inside the stator, female screws are provided on the inner peripheral surface of the rotor, and provided on the outer peripheral surface of the table fixing means. It is also possible to adopt a configuration in which the table is moved up and down by screwing with a male screw.

[0069]

According to the present invention, the gravitational load of the driven body is offset without increasing the inertial mass of the driven object, increasing the resistance and disturbance by the additional device, and without causing the stick-slip phenomenon. be able to.

Therefore, the drive source itself is not affected by the gravitational load of the driven body at all, and when the driven body is moved up and down, particularly when the driven body is moved upward, the output of the drive source is entirely affected. The acceleration and deceleration of the driving body and the work performed by the driven body can be spent. Further, since the load acting on the drive source is reduced, heat generation from the motor or the like serving as the drive source is also reduced. In particular, in a machine tool or the like, it is possible to perform stable processing without being affected by thermal expansion or the like. .

Further, since the hermetic chamber is hermetically closed by utilizing the aerostatic pressure guide mechanism by integrally connecting the hermetic chamber to the aerostatic pressure guide mechanism, a special method for hermetically sealing the hermetic chamber is provided. There is no need for such a sealing material, and it is possible to prevent the sliding contact resistance of the members and the occurrence of the stick-slip phenomenon.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a machine on which a balance mechanism of the present invention is mounted.

FIG. 2 is a schematic view showing another embodiment of a machine on which the balance mechanism of the present invention is mounted.

FIG. 3 is a schematic view showing still another embodiment of a machine equipped with the balance mechanism of the present invention.

FIG. 4 is a side sectional view showing an embodiment of a vertical axis linear motion mechanism on which a balance mechanism of the present invention is mounted.

FIG. 5 is a conceptual view showing a balance mechanism of a counter balance system.

FIG. 6 is a conceptual diagram showing a hydraulic cylinder type balance mechanism.

FIG. 7 is a conceptual diagram showing a pneumatic cylinder type balance mechanism.

FIG. 8 is a conceptual diagram illustrating an example of a machine without a balance mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vertical axis linear motion mechanism 2 Table 3 Table fixing means 4 Rotation drive mechanism 4 'Servo motor 5 Base 6 Stator 7 Rotor 8 Bolt 9 Male thread 10 Female thread 11 Stator core 12 Coil 13 Rotor core 14 Magnet 15 Spacer 17 Retainer 18 Bolt 19 Guide Pin 20 Bolt 21 Hole 22 Through Hole 23 Bolt 24 Hole 25 Through Hole 26 Rotation Detector Mounting Member 26a Projection 27 Pulse Coder 27a Encoder Disk 27b Board 28 Bolt 29 Bolt 30 Hole 31 Female Screw 32 Pipe 33 Nozzle 34 Pipe 35 36 Pipe Line 37 Nozzle 38 Pipe Line 39 Nozzle 40 Pipe Line 41 Pipe Line 42 Pipe Line 43 Seal Material 101 Machine 102 Driven Body 103 Drive Mechanism 104 Feed Screw 105 Balance Mechanism 106 Counterway Light 107 Flexible connection means 108 Pulley 109 Pulley 110 Balance mechanism 111 Hydraulic cylinder 112 Pressure source 113 Pressure adjustment means 114 Drain 115 Tank 116 Balance mechanism 117 Pneumatic cylinder 118 Flexible connection means 119 Pressure adjustment means 120 Pressure source 121 Drain 122 machine 123 motor 124 feed screw 125 driven body 126 support column 127 sliding support member 128 sliding support member 129 circumferential groove 130 circumferential groove 131, 132 pipe 133 external pipe 134 external pipe 135 pressure source 136 gap 137 gap 138 Sealed chamber 139 Regulator 140 External conduit 141 Pressure adjusting means 142 Pressure source 143 Machine 144 Base 145 Feed screw 146 Motor 147 Driven object 148 Slider mechanism 149 Column 150 Screw 151 conduit 152 conduit 153 outer pipe 154 outside pipe 155 pressure source 156 gap 156a gap end 156b gap end 157 sealed chamber 158 outside pipe 159 Regulator

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FIF16F 15/28 B23Q 1/14 B (58) Investigated field (Int.Cl. ⁷ , DB name) B23B 47/26 B23Q 1 / 00-1/76 B23Q 11/00 F16C 32/06 F16F 15/28

Claims (4)

(57) [Claims] 1. A driven body balance mechanism for canceling or reducing a gravitational load generated by the weight of a driven body that moves vertically in a direction opposite to gravity, wherein an outer peripheral portion or an inner peripheral portion of the driven body is formed by air. A hermetic chamber is supported by the static pressure guide mechanism in the horizontal direction, and a closed chamber communicating with the air discharge passage of the air static pressure guide mechanism is provided so as to surround either the upper end or the lower end of the driven body. Wherein the air pressure of the driven body supports a gravitational load generated by the weight of the driven body. 2. The hermetic chamber is sealed with air having a pressure higher than the pressure in the hermetic chamber discharged from an air discharge passage of the static air pressure guide mechanism.
A driven body balance mechanism according to any one of the preceding claims. 3. The air static pressure guide mechanism constitutes a screw mechanism for feeding the driven body in a vertical direction.
3. A balance mechanism for a driven body according to claim 2. 4. The driven body according to claim 1, wherein the closed chamber is provided with a regulator for discharging air to maintain a constant air pressure in the closed chamber. Balance mechanism.