JP2012026563A - Reverse rotation preventing mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reverse rotation preventing mechanism which attains a cushion function not by a servo motor and a stepping motor required for a controller but by ON/OFF of a mere DC motor equal to valve operation of an air cylinder, and attains high thrust, high speed, a self holding function and the like by ON/OFF of a mere DC motor without using a decelerator or a brake mechanism and in which reverse rotation is prevented (holding of thrust is possible) in an OFF state of a current.SOLUTION: A linear movement distance of a retainer 3 is 1/2 times as long as a movement distance of an output member and the maximum thrust of the retainer 3 is twice as large as that of the output member. Thereby, when force is applied to the retainer 3 in an axial direction by compression springs 8 and 9, a cushion function, reverse rotation prevention and penetration prevention are made possible.

Description

The present invention relates to a device for electrification using an electric motor instead of a device that conventionally uses an air cylinder.

1. A rotating linear conversion mechanism using a coil roller.
U. S. Patent US6, 684, 728 B2
Japanese Patent Application 2000-369291
JP 2005-188731 A
Patent No. 4437268
2, Air cylinder.
3, trapezoidal screw.
4. Ball screw.

The conventional apparatus using the air cylinder has advantages such as small size, high thrust, and high speed. Disadvantages include low energy efficiency and the need for piping and air sources. The greatest advantage is the low cost of the device alone.
From the above viewpoint, the following two points can be considered as a problem to complete an electric actuator that can compete with the air cylinder.
1. Regarding the cushion function, it is achieved by simply turning on and off the DC motor, which is comparable to the valve operation of the air cylinder, not the servo motor or stepping motor that requires a controller.
2. High thrust, high speed, and self-holding function, etc. are achieved by simply turning the DC motor on and off without using a speed reducer or brake mechanism, and not reversing when the current is off (holding thrust) Is possible).

In the rotating linear conversion device using the coil roller, the following two points become clear when focusing on the moving distance of the retainer in the linear direction and the rotating speed of the retainer.
1. The linear movement distance of the retainer is ½ of the movement distance of the output member, and the maximum possible thrust of both of them is twice that of the output member of the retainer. This enables a cushion function, prevention of reverse rotation and prevention of biting when a force is applied to the retainer in the axial direction by a compression spring.
This can be inferred as follows.
1-1. The fact that the moving distance is ½ means that the lead is halved when compared with a trapezoidal screw or the like, which is advantageous when it is desired to prevent reverse rotation. It is a factor.
Next, the presence of axial force in the retainer means that there is a third force as compared with a wedge or the like, which is an advantageous factor for preventing biting.
Next, the fact that the load (front third force) that can be applied to the retainer is twice that of the output member is a factor that enables the shock absorbing function corresponding to the cushion of the air cylinder.
1-2, the rotational speed of the retainer is ½ of the rotational speed of the drive member, and when a compression spring is incorporated between the retainer end surface and the drive member, the rotational force can be transmitted from the drive member to the retainer by a frictional force. This is also one of the factors that can prevent reversal without biting.
1-3, Contrary to items 1 and 2 above, applying a force in the axial direction to the retainer as a negative factor is a disadvantageous factor for preventing reversal when considering only that.
2. In addition, as technical contents other than the previous item 1,
2-1, The axial movement of the retainer when the coil roller slips can be controlled by the direction of the rotational force generated by the frictional force on the retainer.
2-2. It is possible to apply the spring force generated in the retainer to the thrust of the output member.
The above technical contents can be combined comprehensively and numerically selected to achieve the structure of the scope of the claims of the present invention.

1. It has a cushion function that can be operated only by turning on and off the DC motor, and also enables a high-speed actuator that prevents reverse rotation (self-holding) and prevents biting.
2. Enables high thrust, high efficiency, reverse rotation prevention (self-holding) actuators that can be operated only by turning on and off the DC motor without a reduction gear and a brake.
3. The above two items can be countered in terms of cost to an apparatus using an air cylinder (in consideration of piping, air source, energy cost, etc.) when viewed comprehensively.

Hereinafter, it will be described according to the drawings.
FIG. 1 is a sectional view in the axial direction of the present invention when used in a device having an impact absorbing function, and in particular, an electric actuator that uses a conventional air cylinder and opposes a stopper cylinder used for a conveyor, etc. The functions require a moving part weight of about 10 kg, a moving distance of about 50 mm, and a moving time of about 0.5 seconds.
Hereinafter, description will be made with reference to FIG.
The cylinder 1 is linearly moved by being guided by two guide rods 12 (one is omitted). The rod 2 is guided by the two flanged sliding bearings 5 fixed to the housing 13 and can only rotate. The retainer 3 is guided such that the inner diameters at both ends are in sliding engagement with the outer diameter of the rod 2. In the retainer 3, a plurality of (3 to 8) grooves are machined at an inclination angle, and the coil roller 4 is rotatable in each of these grooves and is assembled so as to be pressed against both the cylinder 1 and the rod 2. In addition, steel balls are arranged at both ends of the coil roller with respect to the axial force. Stoppers 6 and 7 are fixed to the rod 2. Further, compression coil springs 8 and 9 are respectively incorporated between the end surface of the retainer 3 and the stoppers 6 and 7. Next, the operation will be described.
When the rod 2 is rotated by the DC motor 14, the cylinder 1 moves in the axial direction, and the retainer 3 moves in the axial direction by 1/2 of the cylinder 1. At this time, the compression coil springs 8 and 9 expand and contract, respectively. The force generated by the compression coil springs 8 and 9 enables a reverse rotation prevention mechanism having an impact absorbing function and a biting prevention function as described in the previous section [Means for Solving the Problems].
In this regard, it is extremely complicated to calculate numerically, but it is easy to obtain an optimum value comprehensively through experiments.
Hereinafter, specific numerical values of the present invention achieved by experiments will be described.
As the required functions, the movable part weight is 10 kg, the movable distance is 50 mm, and the time required for the movement is 0.5 seconds. (In this case, when the rod 2 rotates once, the cylinder 1 moves 7 mm)
The inner diameter of the cylinder 1 is 40 mm, the outer diameter of the rod 2 is 20 mm, the outer diameter of the coil roller 4 is 10.1 mm, the length is 20 mm, the inclination angle is 5 degrees, the number is four, and the fluctuation range of the force of the compression coil springs 8 and 9 is 2 kgf to 35 kgf. , DC motor output 27.7W.
Next, when the required functions are expanded, the specific numerical values can be changed so as to be functionally similar.
FIG. 2 is an axial cross-sectional view of the present invention when used in a clamp device or the like.
The difference from FIG. 1 is that an angular ball bearing is used in place of the flanged sliding bearing.
A compression coil spring 8 is incorporated between the retainer 3 and the movable member 10.
As a required function, the output (cram force) is 100 kgf or more, and the impact value is achieved by the following main values as a negligible range (in relation to the moving part mass and speed).
(In this case, when the rod 2 rotates once, the cylinder 1 moves 1 mm)
The inner diameter of the cylinder 1 is 40 mm, the outer diameter of the rod 2 is 20 mm, the outer diameter of the coil roller 4 is 10.1 mm, the length is 38 mm, the inclination angle is 1 degree, the number is 6, and the fluctuation range of the force of the compression coil springs 8 and 9 is 4 kgf to 8 kgf. DC motor output 77W.
In addition, as an effect of the present invention of FIG. 2, it can be easily implemented by paying attention to the difference between the thrust at the time of clamping and the holding force at the time of releasing the clamp.

  An axial direction sectional view of the present invention provided with an impact absorption function.   An axial direction sectional view of the present invention used for a clamp device etc.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Rod 3 Retainer 4 Coil roller 5 Sliding bearing 6 and 7 Stopper 8, 9 Compression coil spring 10 Angular ball bearing 11 Movable member 12 Guide rod 13 Housing 14 DC motor

Claims (3)

In a cylinder having a cylindrical inner peripheral surface, a rod having a cylindrical outer peripheral surface is arranged so as to have the same axis, and a plurality of coil rollers having the same shape are pressed against the cylindrical surfaces between the cylindrical surfaces. And a rotating linear conversion device in which the retainer is used so that the central axis of the coil roller maintains an inclination angle with the same axis, and the end surface of the retainer is arranged with the same axis. A reverse rotation preventing mechanism for use in the rotating linear conversion device, characterized in that it has a right angle and the end surface is pressurized by a compression coil spring. 2. The reverse rotation prevention mechanism according to claim 1, wherein the compression coil spring exhibits an impact absorbing function by being attached between the end surface of the retainer and the rotating side. The reverse rotation prevention mechanism according to claim 1, wherein the compression coil spring is used for a clamping function or the like, which is attached between the end face of the retainer and the linear output side.

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