JP4471874B2 - Linear drive - Google Patents

Description

  The present invention relates to a linear drive device that telescopically expands and contracts in the ascending / descending direction, for example.

  Conventionally, so-called scalar robots (horizontal articulated robots), in which a plurality of arm members are rotatably connected, are often used to transport various articles such as semiconductor wafers (Patent Document 1).

  In such a scalar robot, a linear drive device that telescopically expands and contracts is used to drive the entire arm members up and down (Patent Document 2).

In the conventional linear drive device disclosed in Patent Document 2, three ball screw shafts are set up in a robot body, and these ball screw shafts are rotated by a motor. Each ball screw shaft is inserted through three ball screw nuts provided on the lower lifting base of the lower lifting cylinder that moves upward and downward from the robot body. Further, three ball screw shafts are set on the lower lift base, and these ball screw shafts are rotated. Each ball screw shaft is inserted through three ball screw nuts provided on the upper lift base of the upper lift cylinder that moves upward and downward from the lower lift cylinder. A ball spline shaft is provided between the robot body and the lower lift base in order to transmit the rotational driving force of the motor provided on the robot body to the three ball screw shafts provided on the lower lift base. When the motor is driven to rotate, the six ball screw shafts rotate, and the lower elevating cylinder (lower elevating base) and the upper elevating cylinder (upper elevating base) are telescopically driven to extend and retract relative to the robot body.
JP2000-40728 JP2001-9765

  As described above, conventionally, in order to extend and drive the three members, that is, the robot body (first unit), the lower lift cylinder (second unit), and the upper lift cylinder (third unit), It was necessary to provide a ball spline shaft for transmitting the rotational driving force inside separately from the six ball screw shafts. By providing the ball spline shaft, a pulley for transmitting the rotational driving force thereto is required. Further, in order to transmit the rotational driving force to the pulleys, it is necessary to hang the timing belts over the pulleys. As a result, the structure of the linear drive device becomes complicated, which hinders downsizing and cost reduction.

  The present invention has been made in view of the above-described problems, and an object thereof is to simplify the structure of a linear drive device configured such that at least three units move relative to each other.

According to the linear drive device of the present invention, the first unit, the second unit, and the third unit are arranged in this order, and are provided so as to move relative to each other along the same axis. The unit and the second unit are connected to each other in the axial direction by a first screw shaft and a first nut screwed to the first screw shaft, and the first screw shaft or the first nut rotates. The second unit and the third unit are connected to each other in the axial direction by a second screw shaft and a second nut screwed to the second screw shaft. And the second screw shaft or the second nut is arranged so that a distance between them is changed by rotating, the first screw shaft and the second screw. And the second unit is driven to rotate the first screw shaft or the first nut, and the second screw shaft or the second nut. And a rotational driving force of the motor via the one single-tooth timing belt, the first screw shaft or the first nut, and the second screw shaft or the first 2 is transmitted to the nut .

  Further, the first nut and the second screw shaft are rotatably attached to the second unit, and the first nut and the second screw shaft are rotationally driven by the motor. .

  Each of the first unit, the second unit, and the third unit is provided with a cylindrical cover, and the cover of the first unit is inserted into the inner periphery of the cover of the second unit. The cover of the second unit is inserted into the inner periphery of the cover of the third unit, and the first unit, the second unit, and the third unit are telescopically driven to expand and contract by the rotational drive of the motor. It is comprised so that it may be.

  According to the present invention, the structure of the linear drive device configured such that at least three units move relative to each other can be simplified.

  FIG. 1 is a front sectional view showing a state in which a linear drive device 1 according to an embodiment of the present invention is extended, FIG. 2 is a front sectional view showing a state in which the linear drive device 1 is contracted, and FIG. FIG. 4 is a front sectional view in which details for explaining the power transmission mechanism of the linear drive device 1 are omitted, and FIG. 5 is an arrow Y1 in FIG. 3 in a state where the linear drive device 1 is extended. FIG. 6 is a perspective view showing a state where a cover is removed in FIG. 1.

  In these drawings, as well shown particularly in FIG. 5, the linear drive device 1 includes a first unit 11, a second unit 12, and a third unit 13 arranged in order from the bottom, and a longitudinal axis. Are provided so as to move relative to each other.

  As shown well in FIGS. 1 and 6, the first unit 11 has four plate-like posts 21 a to 21 d that are curved along the peripheral surface attached to the upper surface of a rectangular plate-like substrate 14. A ring 22 is attached to the upper ends of the posts 21a to 21d, and the structure of the first unit 11 is constituted by these.

  Of the four posts 21a to 21d, guide rails 23a, b for slidably supporting the second unit 12 are attached to the inner surfaces of the two opposing posts 21a, 21c in parallel with the axis. Yes.

  A plurality of cylindrical covers 11a are attached to the outer peripheral surfaces of the post columns 21a to 21d with screws. The substrate 14 is provided with four round holes 14a to 14d (not shown), and fans 24a to 24d with motors for ventilation are attached to the lower surface of the substrate 14 in accordance with the respective holes 14a to 14d. It has been. A wiring hole 14e is provided at the center of the substrate 14, and a plurality of holes (not shown) for attachment are provided at four corners of the substrate 14.

  The second unit 12 has two plate-like intermediate sliders 32a and 32b facing each other and two plate-like intermediate posts facing each other over the ring 31 arranged at the upper end and the substrate 34 arranged at the lower end. 33a and 33b are respectively attached. The structure of the 2nd unit 12 is comprised by these. Main portions of a power transmission mechanism described later are attached to the substrate 34.

  Guides 35a and 35b that are movable along guide rails 23a and 23b provided in the first unit 11 are attached to the outer surfaces of the intermediate sliders 32a and 32b. Accordingly, the second unit 12 is movable along the axis while being concentrically held with respect to the first unit 11.

  Guide rails 36a and 36b for slidably supporting the third unit 13 are attached to the inner surfaces of the intermediate posts 33a and 33b in parallel with the axis.

  A plurality of cylindrical covers 12 a are attached to the outer peripheral surface of the ring 31 with screws. The plurality of covers 12a are connected to each other by an appropriate connecting metal fitting and a screw. When the second unit 12 contracts (lowers), the cover 11a of the first unit 11 is inserted inside the cover 12a.

The third unit 13, the lower surface of the upper substrate 15 disposed at its upper end, two opposite support plates 41a, and b is attached, the support plate 41a, the mounting base 42 is mounted et Re to the lower end of the b ing. Further, two opposing plate-like end sliders 43a and 43b are attached to the lower surface of the attachment base 42, and the lower substrate 45 is attached to the lower end thereof. Further, two auxiliary plates 44a and 44b are attached to the lower side surfaces of the end sliders 43a and 43b.

  Guides 46a and 46b that are movable along guide rails 36a and 36b provided on the second unit 12 are attached to the outer surfaces of the end sliders 43a and 43b, respectively. As a result, the third unit 13 can move along the axis while being concentrically held with respect to the second unit 12.

  The upper substrate 15 and the mounting base 42 are each provided with a large hole 15a, 42a at the center, and a load to be lifted and lowered by the linear drive device 1 is attached to the mounting base 42 using these holes 15a, 42a. It is done. As the load, for example, a scalar robot as described above is attached.

  A plurality of cylindrical covers 13 a are attached to the outer peripheral surface of the upper substrate 15 with screws. When the third unit 13 contracts (lowers), the cover 12a of the second unit 12 is inserted inside the cover 13a.

  Next, the power transmission mechanism of the linear drive device 1 will be described.

  As is well shown in FIG. 4, the first unit 11 and the second unit 12 are axially connected to each other by a first screw shaft 51 and a first nut 52 screwed to the first screw shaft 51, and the first unit 11 and the second unit 12, respectively. As the nuts 52 rotate, the distance between them varies.

  That is, the lower end portion of the first screw shaft 51 is fixed to the upper surface of the substrate 14 by the fixture 51a, and the first nut 52 is integrally formed with the pulley 53 that is rotatably supported by the bearing 54. It is designed to rotate. The bearing 54 is fixed to the substrate 34 of the second unit 12, and the first nut 52 moves in the axial direction together with the substrate 34.

  The second unit 12 and the third unit 13 are connected to each other in the axial direction by a second screw shaft 55 and a second nut 56 screwed thereto, and the second screw shaft 55 rotates. The distance between them is variable.

  That is, the second screw shaft 55 has a pulley 57 attached to the lower end thereof, and is supported by a bearing so that the second screw shaft 55 and the pulley 57 rotate integrally. The bearing is fixed to the substrate 34, and the second screw shaft 55 moves in the axial direction together with the substrate 34. Further, the second nut 56 is fixed to the lower substrate 45 of the third unit 13 by a bracket 45a.

  Here, the first screw shaft 51 and the second screw shaft 55 are opposite to each other in the screw winding direction. That is, the first screw shaft 51 is a left-handed screw, and the second screw shaft 55 is a right-handed screw. In these cases, ball screws are used.

  Accordingly, when the first nut 52 and the second screw shaft 55 rotate rightward in plan view, the first nut 52 moves upward with respect to the first screw shaft 51, and the second nut 56 also moves upward with respect to the second screw shaft 55.

  On the contrary, when the first nut 52 and the second screw shaft 55 rotate leftward in plan view, the first nut 52 moves downward with respect to the first screw shaft 51, Similarly, the second nut 56 moves downward relative to the second screw shaft 55.

  Thus, when both the 1st nut 52 and the 2nd screw shaft 55 rotate in the same direction, the 2nd unit 12 and the 3rd unit 13 raise simultaneously with respect to the 1st unit 11, or simultaneously Descend.

  A one-tooth timing belt 59 is stretched over two pulleys 53 and 57 and a pulley 58 attached to the output shaft of the motor M1. That is, the two pulleys 53 and 57 are rotationally driven in the same direction by the rotation of the motor M1. The motor M1 is a gear motor and is controlled to rotate forward or reverse.

  In order to adjust the tension of the timing belt 59, two idlers 60a and 60b are provided in contact with the outside of the timing belt 59.

  Next, the operation of the linear drive device 1 will be described.

  When the motor M1 is driven to rotate, the pulleys 53 and 57 rotate via the timing belt 59, and the first nut 52 and the second screw shaft 55 rotate in the same direction. Thereby, the second unit 12 and the third unit 13 move in the axial direction simultaneously with respect to the first unit 11. Depending on the rotation direction of the motor M1, the linear drive device 1 expands or contracts telescopically.

  When a scalar robot or the like is attached to the attachment base 42, the hole 15a of the upper substrate 15 is thereby blocked, and the air inside the linear drive device 1 is mainly a gap between the cover 13a and the cover 12a. (Clearance) and the clearance between the cover 12a and the cover 11a. At that time, since the gaps are open downward (floor surface), air is sucked in from below and exhausted downward. Thus, since the movement of the air accompanying the expansion and contraction of the linear drive device 1 occurs below the linear drive device 1, even if foreign matter such as dust comes in and out of this, an object (wa -Since it is a position away from (c), such an influence on the workpiece is minimized.

  Also, the internal air is exhausted by the fans 24a to 24d on the lower surface. That is, the internal air is exhausted by the fans 24a to 24d in both cases of expansion and contraction.

  Therefore, it is not necessary to pay close attention to air leakage from the covers 13a, 12a, 11a and the like for the entire linear drive device 1, and no special sealing material is required, thereby simplifying the cover structure. Can be manufactured at low cost.

  Even when water drops or the like are applied not only to the inflow / outflow of air but also to the outside of the linear drive device 1, there is very little possibility that the surface of the cover similarly flows downward and enters the linear drive device 1. Furthermore, even when welding is performed in the vicinity of the linear drive device 1, the spatter is protected without entering the linear drive device 1.

  Then, the first screw shaft 51 and the second screw shaft 55 are set so that the screw winding directions are opposite to each other, and the first nut 52 and the second screw shaft 55 are rotatably held by the substrate 34, In addition, since the motor M1 is attached to the substrate 34 and the first nut 52 and the second screw shaft 55 are rotationally driven in the same direction by the rotational driving force, the second unit is configured by a power transmission mechanism having a simple structure. 12 and the third unit 13 can be extended and contracted simultaneously. For example, the rotational force can be transmitted by two pulleys 53 and 57, and the timing belt 59 of one tooth (a type of belt having teeth on one side), not both teeth (a type of belt having teeth on both sides). Transmission of rotational force is possible. By these, cost reduction can be achieved.

  Further, since the configuration of the power transmission mechanism is simple, there is little interference inside the linear drive device 1, and the linear drive device 1 can be miniaturized.

  Incidentally, when the first screw shaft 51 and the second screw shaft 55 have the same winding direction, the first nut 52 and the second screw shaft 55 attached to the substrate 34 of the second unit 12 are opposite to each other. Must rotate in the direction. For this purpose, for example, the timing belt 59 needs to have both teeth instead of one tooth, the first nut 52 needs to be rotated by one tooth, and the second screw shaft 55 needs to be rotated by the other tooth. .

  For example, as shown in FIG. 7, the timing belt 59 has both teeth and is driven to rotate by the motor M1, and the first nut 52 and the second screw shaft 55 are connected to the opposite sides of the timing belt 59. Need to drive with teeth. This complicates the timing belt 59, and the idlers 60c and d for supporting the timing belt 59 are essential and cannot be omitted.

  In addition, in order to rotate the first nut 52 and the second screw shaft 55 in the opposite directions while the timing belt 59 remains one tooth, the timing belt 59 and the first nut 52 or the second screw shaft 55 It is necessary to provide an intermediate gear between them.

  Thus, when the 1st screw shaft 51 and the 2nd screw shaft 55 are made into the same winding direction, a structure becomes complicated, the freedom degree of arrangement | positioning decreases, and maintainability worsens.

  In contrast, when the first screw shaft 51 and the second screw shaft 55 are made to have the screw winding directions opposite to each other as in the present embodiment, the timing belt 59 may be a single tooth and the idler 60a. , B can be omitted, and the structure is simplified. That is, since the timing belt 59 may be a single tooth, the work of putting the belt is easy, and the assembling property and the maintenance property are good. Since the idlers 60a and 60b can be omitted, dust generated due to friction between the timing belt 59 and the idlers 60a and 60b can be reduced, thereby extending the life of the timing belt 59 and reducing noise. It can be reduced. Since the structure becomes simple, the driving efficiency is improved, a space is provided, it is advantageous for storing the movable cable, and it is advantageous for stabilizing the accuracy.

  In the embodiment described above, the first screw shaft 51 is left-handed and the second screw shaft 55 is right-handed, but these may be reversed. Various structures other than those described above can be adopted as the structures of the first unit 11, the second unit 12, and the third unit 13. The material of each member is mainly a metal material such as an aluminum alloy or steel, but it is also possible to use a material such as synthetic resin, synthetic rubber or wood together with these.

  In the embodiment described above, the fans 24a to 24d may be omitted and only the holes may be formed. A plurality of sets of power transmission mechanisms may be mounted. Each unit has a cylindrical shape, but may have an elliptical cylindrical shape or a rectangular cylindrical shape. Although the linear drive device 1 that expands and contracts in two stages by three units has been described, it may be configured to extend and contract in three or more stages using four or more units.

  In addition, the structure, shape, dimensions, number, material, etc. of the entire linear drive device 1 or each part can be appropriately changed in accordance with the spirit of the present invention.

  The present invention can be used as an elevating device such as an elevator or a lift as a telescopic drive mechanism such as an industrial robot arm.

It is front sectional drawing of the state which the linear drive device concerning embodiment of this invention extended | stretched. It is front sectional drawing which shows the state which the linear drive device contracted. It is the plane sectional view which omitted a part of linear drive device. It is front sectional drawing for demonstrating the power transmission mechanism of a linear drive device. It is a perspective view in the state where the linear drive device extended. It is a perspective view which shows the state which removed the cover in FIG. It is a figure which shows the example in the case of driving with the timing belt of both teeth.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Linear drive device 11 1st unit 12 2nd unit 13 3rd unit 11a, 12a, 13a Cover 34 Board | substrate 51 1st screw shaft 52 1st nut 53, 57, 58 Pulley 55 2nd screw shaft 56 2nd Nut 59 timing belt M1 motor

Claims (4)

The first unit, the second unit, and the third unit are arranged in this order, and are provided so as to move relative to each other along the same axis,
The first unit and the second unit are axially connected to each other by a first screw shaft and a first nut screwed to the first screw shaft, and the first screw shaft or the first nut is It is arranged so that the distance between them can be changed by rotating,
The second unit and the third unit are axially connected to each other by a second screw shaft and a second nut screwed to the second screw shaft, and the second screw shaft or the second nut is It is arranged so that the distance between them can be changed by rotating,
In the first screw shaft and the second screw shaft, the winding directions of the screws are opposite to each other,
The second unit is provided with a motor that rotationally drives the first screw shaft or the first nut, and the second screw shaft or the second nut,
The rotational driving force of the motor is transmitted to the first screw shaft or the first nut, and the second screw shaft or the second nut through one single-tooth timing belt. ,
The linear drive device characterized by the above-mentioned. The first unit, the second unit, and the third unit are all cylindrical,
Wherein the second unit, the and first nut and said second threaded shaft rotatably mounted, these first nut and the second screw shaft is rotationally driven by said motor,
The linear drive device according to claim 1. Two plate-shaped intermediate sliders facing each other are attached to the second unit across a ring disposed at the upper end and a substrate disposed at the lower end,
On the substrate, the first nut and the second screw shaft are rotatably supported by a bearing fixed to the substrate,
Guides that are movable along guide rails provided in the first unit are attached to the outer surface of the intermediate slider.
The linear drive device according to claim 2. The first unit, the second unit, and the third unit includes a cylindrical cover, respectively,
The cover of the first unit is inserted into the inner periphery of the cover of the second unit, the cover of the second unit is inserted into the inner periphery of the cover of the third unit,
By the rotational drive of the motor, the first unit, the second unit, and the third unit are configured to be telescopically driven in a telescopic manner.
The linear drive device according to claim 1.