JPH02228520A - Rotary encoder - Google Patents

Abstract

PURPOSE:To enable highly accurate measurement without transmission errors at a low cost by fitting a hollow shaft into a ball screw to integrate. CONSTITUTION:Bearings 3a and 3b are fitted into the outside of a hollow shaft 2. The bearings 3a and 3b are pinched between a frange part of the hollow shaft 2 and a spacer tightened with a nut screwed down on a thread part of the hollow shaft 2 to be blocked from moving along the axis of the shaft 2. An encoder body metal 1 is provided outside the bearings 3a and 3b and the bearings 3a and 3b are also fitted into the inner circumference thereof. A ball screw is guided stably with a support unit made up of the hollow shaft 2, the bearings 3a and 3b and the metal 1. Moreover, a rotation value of the ball screw can be read accurately with a magnetic scale 4 and a magnetic sensor 5 thereby enabling the monitoring of a position of a stage exactly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rotary encoder that obtains a rotation angle as an electrical signal.

(Prior Art) Conventionally, there is a device that uses a ball screw to control the position of a stage or the like.

In this device, in order to rotatably support the ball screw while preventing it from wobbling, the vicinity of one end of the ball screw is supported by a support unit having a bearing, and the vicinity of the other end is supported by a support plate using a bearing.

Then, a motor is connected to one end of the ball screw via a coupling, a rotary encoder is attached to the other end of the ball screw via a coupling, and the stage position is controlled by the output signal of the rotary encoder according to the rotation of the ball screw. It is something.

(Intelligence B to be Solved by the Invention) In the conventional technology as described above, a coupling is used to connect the ball screw and the rotary encoder, so a transmission error may occur in the coupling.

Furthermore, since the bearing that supports the ball screw and the bearing that supports the rotary encoder are separate, two bearings are required, which increases the number of parts and increases costs.

The present invention has been made in view of these conventional problems, and it is an object of the present invention to provide a rotary encoder that can accurately measure the amount of rotation of a ball screw and that can be manufactured at low cost.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes a hollow shaft (2) that fits on the outer periphery of a ball screw, and a main body metal fitting (2) provided on the outside of the hollow shaft (2). 1), and bearings (3a, 3b) provided between the hollow shaft (2) and the main body hardware (1).
) to form a support unit that supports the ball screw, and a scale member (4) is provided on the hollow shaft (2), and a detector (5) for reading the scale of the scale member (4) on the main body hardware (1). The above problem is solved by a rotary encoder characterized in that it is provided with a rotary encoder.

(Function) In the present invention, since the hollow shaft of the rotary encoder is fitted into the ball screw and integrated, the hollow shaft, main body metal fittings, and bearing also function as a support unit for the ball screw. There is no need to provide two bearings. Therefore, the device can be constructed at low cost.

Furthermore, there is no need for a coupling that connects the ball screw and rotary encoder, and since the ball screw and rotary encoder are integrated, highly accurate measurement without transmission errors is possible.

(Example) The present invention will be described below based on the example shown in the drawings.

FIG. 1 is a sectional view of an embodiment of the rotary encoder of the present invention.

Bearings 3a, 3b are fitted on the outside of the hollow shaft 2, which fits on the outer periphery of a ball screw (not shown).
b is sandwiched between the end portion 2a of the hollow shaft 2 and a spacer 9 tightened by a nut 8 screwed into the threaded portion of the hollow shaft 2, thereby preventing the hollow shaft 2 from moving in the axial direction. . The encoder body hardware 1 is provided on the outside of the bearings 3a, 3b, and the bearings 3a, 3b are also fitted on the inner periphery thereof.

That is, the bearings 3a and 3b are provided between the main hardware 1 and the hollow shaft 2.

Oil, water, etc. are on both sides of the bearings 3a, 3b.
A ring rubber seal is provided to prevent entry into the interior of the ring.

A magnetic scale 4 with magnetic graduations formed in the circumferential direction is fixed on the outer periphery of the nut 8, and a magnetic sensor 5 for reading the scale is fixed on the hardware l of the encoder body, facing the scale surface of the magnetic scale 4. has been done.

In addition, an electric board 6 is fixed to the center of the encoder main body hardware l, which has a hole through which a ball screw passes.

Further, reference numeral 7 is a cover for protecting the magnetic scale and the like.

Generally speaking, the encoder body hardware 1 has holes 1a, lb, etc. for mounting the encoder. .

FIG. 2 is a diagram showing a state in which the rotary encoder of FIG. 1 is attached to a ball screw.

The rotary encoder 20 is fixed to a support plate 22 fixed to a base 21 through holes ta and lb. One end of the ball screw 23 is connected to the support plate 2 fixed to the base.
4 by a bearing 25, and the collar 2
The hollow shaft 2 is sandwiched between the nut 26 and the nut 26 which is screwed into the threaded portion 23b. That is, the main body hardware l, the bearings 3a, 3b, and the hollow shaft 2 of the rotary encoder 20 function as a support unit for the ball screw 23.

Between one end of the ball screw 23 on the bearing 25 side and the collar portion 23a, there is a threaded portion 23c.
6 are screwed together. The other end of the ball screw 23 that penetrated through the hollow shaft 2 of the rotary encoder 20 is coupled to a rotating shaft 28a of a motor 28 via a coupling 27. The motor 28 is held by a support plate 29 on the base 21, and is controlled by a control device (not shown) based on signals from the rotary encoder 20.

With such a configuration, the ball screw 23 is stably guided by the support unit composed of the hollow shaft 2, the bearing 3a, the bearing 3b, and the main body hardware 1, and the amount of rotation of the pole screw 23 is controlled by the magnetic scale 4. and magnetic sensor 5
Since the position of the stage 26 can be reliably read, the position of the stage 26 can be accurately monitored.

In addition, in the above explanation, in order to rotate the ball screw 23,
Although the other end of the pole screw 23 is connected to the rotation shaft 28a of the motor 28 via the coupling 27, it goes without saying that the pole screw 23 may be connected to the rotation shaft of the motor 28 by a belt or the like.

In this case, since errors such as belt slippage errors and gear bank lashes do not affect the rotary encoder, there is also the advantage that sufficiently high precision control can be achieved even when a large stage is driven by a small motor.

Further, the detection of the amount of rotation does not have to be performed magnetically, but can be replaced with an equivalent known method that is performed photoelectrically, for example.

Further, in the above description, the scale is formed on the outer periphery of the cylinder, but the scale may be formed on the surface of the disk.

(Effects of the Invention) As described above, since the rotary encoder of the present invention has the function of supporting the ball screw, it is possible not only to form a highly accurate and low-cost control device, but also to save space.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of the rotary encoder of the present invention, and FIG. 2 is a cross-sectional view showing the rotary encoder of FIG. 1 in use when attached to a ball screw. 1...Encoder body hardware, 2...Hollow shaft, 3a, 3b...Bearings, 4...Magnetic scale, 5...Magnetism Sensor, 20...Rotary encoder.

Claims (1)

[Claims] A support unit that supports the ball screw is formed by a hollow shaft that fits around the outer periphery of the ball screw, a main body metal fitting provided on the outside of the hollow shaft, and a bearing provided between the hollow shaft and the main body metal fitting. A rotary encoder, characterized in that a scale member is provided on the hollow shaft, and a detector for reading the scale of the scale member is provided on the metal body.