JPH11255489A - Lift mechanism utilizing screw and control method of its action - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lift mechanism and a control method of its action enabling lift action as a highly efficient safe screw type jack with an output of a relatively small motor, by providing a screw type jack with two mechanism of performing high efficient lift action by combination of a ball screw shaft and its nut and, for instance, self lock action for preventing the dropping down by combination of a trapezoidal screw and its nut. SOLUTION: A ball screw 2 and its nut 13 and a slide screw 5 and its nut 14 and assembled in the same lift device, a heavy load is burdened by the ball screw 2 and its nut, and when a motor 12 is stopped by self lock action of the slide screw 5 and its nut 14 while making stable lift action in high efficiency, safe dropping down prevention is directly performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lifting mechanism using a screw such as a screw jack and a method of controlling the operation of the mechanism.

[0002]

2. Description of the Related Art Conventionally, as a lifting mechanism using a screw, a number of screw-type jacks and screw-type platform jacks have been proposed and known, and some of them have been put to practical use.

[0003] In a screw type lifting mechanism employed in a conventional jack, a trapezoidal screw is used as a typical sliding screw. This trapezoidal screw has a self-locking effect between a trapezoidal screw shaft and a nut screwed thereto. This is to prevent the screw shaft or the nut from being reversed when stopped due to the weight of the object being raised and lowered.

However, a combination of a trapezoidal screw shaft and a nut that performs a self-locking operation is inefficient because of the large sliding friction in addition to the unstable operation due to the quality of lubrication, and requires a large-capacity motor. There's a problem.

[0005] In this regard, when a screw type jack is constructed by combining a ball screw shaft and a ball screw nut, the output of the drive source motor is about 1 / compared to a sliding screw type jack formed by a combination of a trapezoidal screw shaft and its nut. There is an advantage that only about 3 is required. However, since there is no self-locking action between the ball screw shaft and its nut, unless a lock mechanism or a brake mechanism is separately provided, for example, when the motor stops, the ball screw shaft may be subjected to a load applied to the nut. It is dangerous to turn around.
Further, the reliability of the separately provided lock mechanism or brake mechanism is reduced due to indirect locking.

[0006]

SUMMARY OF THE INVENTION In view of the above, the present invention provides a highly efficient lifting and lowering operation by combining a ball screw shaft and its nut in a single screw type jack. A lifting mechanism that incorporates two mechanisms that perform a self-locking action to prevent falling due to the combination of nuts, and that can be raised and lowered as a highly efficient and safe screw-type jack by the output of a relatively small motor and its operation It is an object of the present invention to provide a control method as described above.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems by assembling a ball screw and a nut thereof, and a slide screw and a nut thereof in the same lifting device. The self-locking action of the slide screw and its nut directly prevents the safe fall when the motor is stopped, while the heavy load is carried by the ball screw and its nut, and the highly efficient and stable lifting operation is performed. It is characterized by the following.

In the present invention, the above mechanism is constituted by a ball screw shaft, a ball screw nut screwed on the same, a trapezoidal screw shaft as an example of the slide screw shaft, and a slip screw nut screwed on the same. Alternatively, it can be configured by screwing a ball screw nut and a slide screw nut together on one screw shaft. Further, in the mechanism having the above structure, the rotation of the motor is transmitted to the nut, and the nut is moved up and down on the screw shaft fixed upright, or the ball is mounted on a single ball screw shaft upright. Screw a screw nut and a sliding screw nut, rotate the screw shaft, and raise and lower the ball screw nut on the screw shaft,
The slide screw nut may be slightly rotated. Further, in the mechanism of the present invention, a guide mechanism for guiding and supporting the ascending and descending operation of a member which moves up and down by rotation of the nut or the screw shaft may be provided in parallel with the screw shaft.

In the above-mentioned lifting mechanism of the present invention, in order to make a slight difference between the speed of the feed by the ball screw and the speed of the feed by the slide screw, the feed by the slide screw is controlled so as to be always slightly faster than the feed by the ball screw. These feed differences are absorbed by the clutch to ensure high-efficiency feed by the ball screw, and at the same time, to ensure the self-locking action by the slide screw and its nut when necessary.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a mechanism of the present invention having the above-described structure and a control mode thereof will be described with reference to the drawings. 1 is a front view of a main part of a first example of the lifting mechanism of the present invention, FIG. 2 is a left side view of the mechanism of FIG. 1, FIG. 3 is a front view of a main part of a second example of the present invention, FIG. 3 is a left side view in which a part of the mechanism of FIG. 3 is omitted, FIG. 5 is a front view of a main part of a third example of the mechanism of the present invention, and FIG. 6 is a left side view in which a part of the mechanism of FIG. 7 is a front view of a main part of a fourth example of the mechanism of the present invention, FIG. 8 is a left side view of the mechanism of FIG. 7, FIG. 9 is a ball screw shaft, and a slide screw nut for the ball screw shaft screwed on this shaft. FIG. 10 is an enlarged sectional view of a main part of the mechanism of FIG.

In FIG. 1 and FIG. 2, reference numeral 1 denotes a frame which is mainly formed of a pipe material, a shape steel and the like, and is assembled in a generally tower shape. Is provided with an upper underframe 1b for disposing.

Reference numeral 2 denotes a ball screw shaft which stands on the lower base 1a and upper underframe 1b of the frame 1 via an upper bearing 3 and a lower bearing 4 respectively, and 5 is parallel to the ball screw shaft 2. In a posture, a trapezoidal screw shaft vertically erected as an example of a sliding screw shaft via an upper bearing 6 and a lower bearing 7 respectively, and these two screw shafts 2 and 5 are located above the respective upper bearings 3 and 6, It is formed on the input shaft portions 2a and 5a acting as an input shaft for the driving force.

In this example, the input shaft portions 2a and 5a have:
In principle, sprockets 8 and 9 of the same diameter and the same number of teeth are attached, the chain 10 is wound around in parallel, and one shaft 2a is connected to the joint 11
And a drive source 12 including a motor and a speed reducer. With this configuration, the rotation of the drive source 12 is synchronously transmitted to the two screw shafts 2 and 5 via the joint 11, the sprocket 8, the chain 10, and the sprocket 9.

At the same height position of the two screw shafts 2 and 5, respectively, a ball screw nut 13 and a trapezoidal screw nut 14 are provided.
Are screwed, and both nuts 13 and 14 are connected by a connecting member 15 and integrated at the same position. Therefore, if the screw shafts 2 and 5 rotate synchronously in the same direction, the nuts 13 and
14 can be moved up and down on the screw shafts 2 and 5 integrally with the connecting member 15.

In the present invention, the lifting and lowering operations of the nuts 13 and 14 integrated via the connecting member 15 are smoothly guided even when a load is applied to the member 15 by an object to be raised or lowered. For this purpose, a so-called linear guide mechanism 16 is provided in the frame 1 in a posture parallel to the screw shafts 2 and 5 in association with the connecting member 15. The linear guide mechanism 16 is formed by a rail member 16a arranged parallel to each of the screw shafts 2 and 5, and a slider member 16b attached to the connecting member 15 and sliding on the rail 16a. Linear guide mechanism.

As described above, the elevating mechanism JU ₁ which is an example of the present invention described with reference to FIGS. 1 and 2 is formed. The mode of use of the elevating mechanism JU ₁ is such that the two nuts 13 and 14 are integrally connected. The target object, equipment, and the like to be lifted and lowered are supported by the member 15, and the two screw shafts 2 and 5 are selectively rotated synchronously in the forward or reverse direction to raise or lower the target to a desired height. In addition to the usage form, it is mainly used in the following forms.

Although not shown, as an example, the four lifting mechanisms JU ₁ of the present invention are arranged at four vertices of a plane rectangle of the ground GL, and the connecting members 15 of each mechanism JU ₁ are connected to the connecting beam 17. Are connected so as to form a substantially polygonal plane, and the polygonal connecting beam 17 supports an object to be lifted and lowered, thereby ascending and descending. In this case, it is a matter of course that the respective connecting members 15 in which the two nuts 13 and 14 in the four lifting mechanisms JU ₁ are integrated are raised and lowered synchronously.

In the lifting mechanism JU ₁ described above,
The connecting member 15 (or the connected connecting beam to be raised and lowered)
Since the two nuts 13 and 14 connected to 17) are a ball screw nut and a trapezoidal screw nut, the lifting force for lifting the connecting member 15 is transmitted mainly to the ball screw nut 13. Therefore, it is convenient to suppress the output of the drive source 12 to a small value, and to use the self-locking effect generated between the trapezoidal screw nut 14 and the trapezoidal screw 5 for drop prevention or braking.

For this purpose, the trapezoidal screw shaft 5 is used, for example, by the screw pitch between the ball screw shaft 2 and the trapezoidal screw shaft 5 or the combination of the pitch and the difference in the number of teeth (ratio) between the sprockets 8 and 9. The feed of the nut 14 is slightly larger than the feed of the nut 13 by the ball screw shaft 2, and furthermore,
By attaching the torque limiter QL to the sprocket 9 of the trapezoidal screw shaft 5 and combining the action of the limiter QL, the feed of the nut 14 by the trapezoidal screw shaft 5 always follows the feed of the nut 13 by the ball screw shaft 2 when ascending. It is desirable to control so that In order to perform such control, in the present invention, a drive source 12 may be provided for each of the shafts 2 and 5 described above.

As described above, the lifting mechanism of the present invention uses a combination of a ball screw shaft and its nut, and a sliding screw shaft and its nut, and is configured to integrally move two nuts vertically. As a result, the target to be raised and lowered is raised and lowered, so that the ball screw shaft and its nut, which require only a small output of the driving source, are used as the main body of the lifting force, and at the same time, there is no self-locking effect, The self-locking action of the sliding screw shaft and its nut, which is not found in the conventional screw type lifting mechanism, ensures that the heavy object is prevented from dropping during lifting.

The lifting mechanism described above can also be implemented in the modes illustrated in FIGS. 3 to 8, and will be described below in order with reference to the drawings. 3 to 8, the same reference numerals as those in FIGS. 1 and 2 denote the same members and the same parts.

A second embodiment of the lifting mechanism according to the present invention illustrated in FIGS. 3 and 4 is the lifting mechanism JU ₁ described with reference to FIGS. 1 and 2 in which the main feed ball screw shaft 2 and the ball screw nut 13 are provided. Instead of the trapezoidal screw nut 14 in the above example,
A slide nut 20 is provided on the same ball screw shaft 2 for drop prevention or lock function, and the slide screw nut 20 is oscillated (small rotation) to prevent the slide screw nut 20 from dropping (locking action). It is. here,
The slide screw nut 20 is supported by an angular bearing 19 and is coupled by a rocking motor 22 via a gear train 21 (gears 21a and 21b) so as to rotate oscillatingly. When the ball screw is fed, the slide screw nut 20 is opened. The second lifting mechanism JU ₂ of the present invention is provided with a function of locking when stopped. 23 is a torque limiter, 24 is a motor 22
Mounting bracket. Mode of use of this mechanism JU ₂ is the same as in the lifting mechanism JU _1.

In the third example of the mechanism of the present invention illustrated in FIGS. 5 and 6, the ball screw shaft 2 is prevented from rotating on the frame 1.
The upper and lower ends of the screw shaft 2 are fixed at 31 and 41, and only one ball screw shaft 2 is provided. The screw nut 13 and the slide screw nut 14 are coaxially rotatably arranged via bearings and screwed, respectively.
The connection member 15 is moved up and down on the screw shaft 2 by simultaneously rotating the two nuts 13 and 14 from the drive source 12 provided on the connection member 15.

5 and 6, reference numeral 12a denotes an output shaft connected to the drive source 12, and 12b and 12c denote drive sprockets provided above and below the shaft 12a, and both sprockets 12b and 12c.
Are connected to input nuts 13a and 14a provided integrally with the two nuts 13 and 14, respectively, via chains 12d and 12e, respectively. Incidentally, 25 is a bundle of cables for supplying power and control signals to the drive source 12 moves up and down to form a third example screw lift mechanism JU ₃ of the present invention with a more components. Mode of use of this mechanism JU ₃ is also the same as mechanism previously described JU _1, JU _2.

FIGS. 7 and 8 show a fourth lifting mechanism according to the present invention.
Illustrate the JU _4, the elevating mechanism JU ₄ is 5, 6
In the lifting mechanism JU ₃ of the third embodiment of the present invention described above, the nuts 13 and 14 are rotated to move the connecting member 15 up and down. In short, the nuts 13 and 14 are rotated at fixed positions. The screw shaft 2 is raised and lowered by being freely fixed, and the lower end of the screw shaft 2 is fixedly connected to the connecting member 15 here.

Therefore, in the lifting mechanism JU ₄ shown in FIGS. 7 and 8, first, two nuts 13 and 14 are connected to the upper frame of the frame 1.
1b is provided coaxially via bearings 61 and 71 so as to be rotatable, respectively, and the two nuts 13 and 14 are provided with a drive mechanism including a drive source 12 having the same configuration as in FIGS. The nuts 13 and 14 are rotated synchronously by being provided and connected to the underframe 1b. The ball screw shaft 2 screwed on the nuts 13 and 14 is formed on the lifting mechanism JU ₄ by fixing the lower end of the ball screw shaft 2 to a connecting member 15 supported by a linear guide mechanism 16 so as not to rotate. Have been. Note that 2
Reference numeral 6 denotes a limit switch that functions as an upper limiter of the member 15. 7 and 8, the same reference numerals as those in FIGS. 6 and 7 denote the same members.

The lifting mechanism JU _{4 of the} present invention illustrated in FIGS.
The lifting mechanisms JU _{1 to} JU _{3 of} the present invention described with reference to FIGS.
They are used in a similar manner.

FIG. 9 shows the thread of the sliding nut 14 which makes sliding contact with the ball screw shaft 2 in the lifting mechanism of the present invention, that is,
FIG. 4 is a cross-sectional view showing an example of the form of the screw thread. The screw thread 14a of the nut 14 is formed in a convex cross-sectional shape that matches the concave cross-sectional shape of the groove 2a of the ball screw shaft 2.

[0029]

The present invention is as described above, and a screw type lifting mechanism is provided for a combination of a ball screw shaft and its nut, a combination of a sliding screw shaft and its nut, or a single ball screw shaft. The ball screw nut and the slide screw nut are screwed and assembled into an elevating device, and the main screw operation for elevating by the ball screw shaft and the ball screw nut is performed, while the slide screw shaft and the slide nut, or ball. The screw shaft and the sliding nut screwed on it are formed to perform a follow-up feed operation to achieve a self-locking function. At the same time as using the ball screw shaft and its nut, the ball screw mechanism has the problem that there is no self-locking action. Of that complemented by safe and direct drop prevention operation of the self-locking effect, the conventional screw-type lifting mechanism may provide a lifting mechanism for the effect is not seen.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of a first example of a lifting mechanism according to the present invention.

FIG. 2 is a left side view of the mechanism of FIG.

FIG. 3 is a front view of a main part of a second example of the mechanism of the present invention.

4 is a left side view in which a part of the mechanism of FIG. 3 is omitted.

FIG. 5 is a front view of a main part of a third example of the mechanism of the present invention.

FIG. 6 is a left side view in which a part of the mechanism of FIG. 5 is cut away.

FIG. 7 is a front view of a main part of a fourth example of the mechanism of the present invention.

FIG. 8 is a left side view of the mechanism of FIG. 7;

FIG. 9 is an enlarged cross-sectional view of a ball screw shaft and a slide screw nut for the ball screw shaft screwed on the shaft;

10 is an enlarged sectional view of a main part of the mechanism in FIG.

[Explanation of symbols]

 Reference Signs List 1 frame 1a base 1b underframe 2 ball screw shaft 3 upper bearing 4 lower bearing 5 trapezoidal screw shaft 6 upper bearing 7 lower bearing 8,9 sprocket 10 chain 11 joint 12 drive source 13 ball screw nut 14 trapezoidal screw nut 15 connecting member 16 Linear guide 17 Connecting beam

Claims (8)

[Claims] 1. A ball screw and a nut thereof, and a slide screw and a nut thereof are assembled in the same elevating device, and a self-locking action is applied to the slip screw and the nut while the ball screw and the nut perform an elevating operation. A lifting mechanism using a screw, characterized in that the lifting mechanism is used. 2. The elevating mechanism according to claim 1, wherein a ball screw nut and a slide screw nut are screwed on one standing ball screw shaft, and both nuts are rotated on the screw shaft to move up and down. . 3. A ball screw nut and a slide screw nut are screwed on one standing ball screw shaft, and the two screw nuts are rotated at fixed positions to raise and lower the screw shaft. Elevating mechanism. 4. A ball screw nut and a slide screw nut are screwed on one standing ball screw shaft, and the screw shaft is rotated to raise and lower the ball screw nut on the screw shaft. 2. The elevating mechanism according to claim 1, wherein the nut is slightly rotated. 5. The lifting mechanism according to claim 1, wherein the ball screw shaft and the slide screw shaft are erected in parallel, and the two screw shafts are rotated to raise and lower nuts screwed on the respective shafts. 6. An object to be raised and lowered is coupled to and supported by an ascending and descending nut or screw shaft, and the ascending and descending nut or screw shaft is supported by a guide support member parallel to the screw shaft. The lifting mechanism according to any one of 1 to 5. 7. The lifting mechanism according to claim 2, wherein the sliding screw nut screwed on the ball screw shaft has a screw thread that slides and joins with a screw groove of the screw shaft. 8. A lifting and lowering mechanism having both a ball screw mechanism and a sliding screw mechanism allows the ball screw mechanism to perform an efficient main feeding operation while the self-locking sliding screw mechanism performs the main feeding operation. A method for controlling a lifting and lowering operation in a lifting and lowering mechanism, characterized in that the sliding screw feed is faster than the ball screw feed so as to always follow, and the difference in feed is absorbed by a clutch or the like.