JPH01228792A - Linear and rotary motion unit - Google Patents

Abstract

PURPOSE:To perform linear progressing motion in high speed for making it possible to perform both linear progressing motion and rotating motion on the same axis by providing spline channels on outer face of a nut for ball screw in order to be able to slide the nut relatively to a guide member. CONSTITUTION:A motor 27 is driven for rotating ball screw shaft 26. In this case, if the ball screw shaft is fixed on linear progressing direction, on account of being regulated a nut 28 in rotary direction with a spline nut 29 (guide member), the nut 28 provided with spline channels on outer periphery of the ball screw 26 performs high speed linear progressing motion. Thereby, a chuck 34 on the top end of the nut 28 also performs linear progressing motion. Again, a motor 32 is driven for rotating the spline nut 29 to make the chuck 34 perform rotary motion around the same axis as linear progressing motion.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a linear rotation unit used in an industrial robot.

Conventional technology Industrial robots in general, and horizontally articulated robots in particular, are
It has the configuration shown in the figure. The configuration will be briefly explained below. In FIG. 2, 1 is a main body, 2 is a first arm 3 is a second arm, 4 is a linear rotating part, and 6 is a chuck. In the horizontal articulated robot configured as described above, the chuck is positioned in a plane by the postures of the first arm and the second arm, and the linear rotation unit 4 positions the chuck 5 in the vertical and rotational directions. is being carried out.

Since the linear rotation unit 4 is located at a position apart from the first arm 2 and the second arm 3, it becomes a heavy load on the motor that drives the first arm 2 and the second arm 3 during positioning on a plane. For the reasons mentioned above, the linear rotating section 4
Reducing the weight of the device is a major challenge for increasing speed. An example of the conventional linear rotation unit mentioned above will be described below with reference to the drawings.

FIG. 3 shows the configuration of a conventional linear rotation unit. In FIG. 3, reference numeral 6 is a motor, whose rotation is transmitted to the ball screw shaft γ by a timing belt. 8 is a ball screw nut. 9 is a spline shaft, which is connected to the plate by a ball screw nut, so that it moves linearly in synchronization with the ball screw nut. 10 is a motor, and a spline nut 11 transmits the rotation of the motor 10 to the spline shaft 9. The operation of the linear rotation unit configured as above will be explained below.

First, in the case of linear motion, the rotation of the motor 6 is transmitted to the 70 ball screw shaft via the shift timing belt. The ball screw shaft is fixed in the linear direction, and since it is connected to the spline shaft 9, the rotational direction is also restricted, so the nut 8 moves in the linear direction. Natsu, To8
The linear motion of is transmitted to the spline shaft 9 through the plate.

In the manner described above, the spline shaft performs linear motion. Next, when performing a rotational movement, the motor 1o rotates and is transmitted to the spline shaft 9 via the timing belt and the spline nut 11. As described above, linear and rotational movements are performed.

Next, a second example of the conventional technology will be described below with reference to the drawings. This case is described in Japanese Patent Publication No. 62-4970, and its outline will be explained below with reference to the drawings. In FIG. 4, 12 is a Boer 7L/screw with a spline groove provided on its outer periphery. 13 is the nut of the ball screw, 14 is the pulley connected to the nut of the pole screw, 16 is the timing belt, and 16 is the pulley.
It is connected to the motor output shaft of 7. 18 is a spline nut, and 1.19 is a pulley connected to the spline nut. 20 is the timing vector/V).

21 is a pulley connected to the motor output shaft 22.

23 is a chuck directly connected to the pole screw shaft of 12. The operation of the linear rotation unit configured as above will be described below. First, when moving in a straight line, the motor 17 rotates and the power is transferred to the pulley 16. Ball screw 1 via timing belt 16 and pulley 14
It is transmitted to No. 3 Nat. Since the movement of the pole screw shaft 12 in the rotational direction is restricted by the spline nut 18, the chuck 23 moves in a straight line. Next, when performing a rotational movement, the motor 22 rotates and the pulley 21 . Timing belt 20. It is transmitted to the spline nut 18 via the pulley 19, and the ball screw shaft 1 is transmitted to the spline groove.
2.

Therefore, the chuck 23 performs a rotational movement. As described above, this linear rotation unit, which is the second example of the conventional technology, performs linear movement and rotational movement.The problem that the invention sought to solveHowever, in the first example of the conventional technology, the mechanical structure Since the structure is complicated and the weight is large, it is not suitable for use in the linear rotation unit 4 of FIG. 2 in a horizontal articulated robot or the like.

In the second example, all rotational torque is transmitted through a spline groove provided on the ball screw shaft 12. Alternatively, when attaching a chuck or the like to the spline grooved pole screw shaft 12, rigidity is required for work, and the diameter of the spline grooved pole screw shaft 12 must be minimized. When the diameter of nut 12 becomes larger, the diameter of nut 13 also becomes larger. During high-speed straight motion, this nut 13 must be rapidly accelerated or decelerated, which places a large load on the motor 17.

The present invention addresses the above-mentioned problems and provides a linear rotation unit that is capable of linear movement at high speed and capable of linear movement and rotational movement on the same axis. The linear rotation unit has a feed screw, a housing that supports the feed screw so that it cannot move in a straight line but can rotate, and a threaded portion that is threadedly engaged with the feed screw on a part or all of the inner surface, The nut has a structure including a nut having a groove on its outer periphery in a direction parallel to the direction in which the screw is fed, and a guide portion that regulates the direction of rotation of the nut along the groove provided in the nut.

Function The present invention has the above-described configuration, and regarding the feed screw portion,
Since no chuck is attached and no rotational torque is transmitted, the diameter can be reduced. During high-speed linear motion, the screw shaft is rapidly accelerated or decelerated, but if the diameter of the screw shaft is reduced, the rotor inertia is reduced, so high-speed linear motion is possible with a small load on the motor.

EXAMPLE Hereinafter, a linear rotation unit according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a linear rotation unit in accordance with the present invention. In FIG. 1, a pulley 24 is fixed to a ball screw shaft 26. As shown in FIG. 25 is motor 2
7 is a pulley directly connected to the output shaft, 2θ is a ball screw shaft, 28 is a ball screw nut with a spline groove on the outer periphery, 29 is a supline nut, 3o is a pulley fixed to a spline nut, and pulley 31 is a pulley fixed to the spline nut. It is connected to -30 by a timing belt. The output shaft of the motor 32 is directly connected to the pulley 31. 33 is a housing that allows the ball screw shaft 26 and the spline nut 29 to rotate without being able to move straight. 34 is joined to the nut 28 by a chuck. The operation of the linear rotation unit configured as above will be described below.

First, by driving the motor 27, the ball screw shaft 26 is rotated via the pulley 26 and the pulley 24. If the straight direction of the ball screw shaft 26 is fixed, the nut 28
Since the rotation direction of the ball screw 28 is restricted by the spline nut 29, the nut of the ball screw 28 moves in a straight line. Therefore, the chuck 34 moves in a straight line. Also motor 32
By driving the chuck 34, the chuck 34 rotates in order to transmit rotational motion to the spline nut 29 via the pulleys 30,31. Since the nut of the pole screw can be rotated arbitrarily, the chuck 34 also rotates. As described above, according to this embodiment, it is possible to configure the unit 1- which can perform linear movement and rotational movement on the same axis.

Effects of the Invention As described above, by providing a spline groove on the outer periphery of the nut of the ball screw, the present invention can provide a linear rotation unit that is capable of coaxial linear movement at high speed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a linear rotation unit of an industrial robot according to a first embodiment of the present invention, FIG. 2 is a perspective view of the industrial robot, and FIG. 3 is a linear rotation unit of a conventional industrial robot. Fig. 4 is a sectional view of main parts of another conventional linear rotation unit. , 33...
·housing. Name of agent: Patent attorney Toshio Nakao et al. 16th
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Claims (2)

[Claims] (1) A rotatable feed screw, a housing that supports the stagnant screw so that it cannot move in a straight line and is rotatable, a nut whose inner surface has a threaded portion that engages with the feed screw, and a nut. 1. A linear rotation unit comprising a guide portion for regulating rotation, wherein the nut is slidable relative to the guide portion through a groove provided on an outer surface of the nut. (2) The linear rotation unit according to claim 1, wherein the guide portion is capable of arbitrarily rotating the nut.