JPS62224571A - Device for reciprocally moving rotary shaft - Google Patents

Abstract

PURPOSE:To increase bending rigidity of a rotary shaft in a vibration grinder by forming a cylindrical part adjacent to a central side of a journal part of each of both end parts of a rotary shaft, with the cylindrical part having a larger diameter than the journal part, and by fitting a pair of hydraulic cylinders for reciprocal moment to the cylindrical part. CONSTITUTION:A rotary shaft 20 to which a grindstone 27 is fixed is supported via journal parts 21 of both end parts by means of bearing main bodies 10 with some extent of freedom of reciprocal movement. A pair of hydraulic cylinders 15 are fitted freely rotatably to cylindrical parts 22 having a larger diameter than the journal parts 21. Drive signals from a reciprocal signal generator 40 make via a servo-amplifier 41 an electric-hydraulic servo-valve 30 reciprocate to feed working oil from a hydraulic unit 31 alternately to hydraulic cylinders 15 and 15, and make a rotary shaft 20 reciprocate while feeding back signals of a displacement detector 45 via an amplifier 42. Thus, bending rigidity of the rotary shaft can be increased, both stroke and frequency of the reciprocal movement can be easily changed, and the stroke can be set with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reciprocating device for a rotary shaft that requires synchronous reciprocating motion, such as a grindstone shaft of a grinding machine that performs vibration grinding.

[Prior art]

This type of reciprocating device for a rotating shaft includes a mechanical type or an oscillation valve type.

[Problem that the invention seeks to solve]

However, since the mechanical type uses an eccentric shaft or a cam, changing the reciprocating stroke requires replacing the eccentric shaft, etc., which is a problem. On the other hand, the oscillation valve type disclosed in Japanese Patent Publication No. 45-39962, for example, allows the stroke to be adjusted with a dial, but the accuracy of setting the stroke and reciprocating speed is not sufficient, and There are problems in that a complicated and special valve device is required and the manufacturing cost increases because there are many moving parts.

In addition, since a flange-like large diameter part is provided protruding from the center of the rotating shaft to provide reciprocating motion, the thickness of the other parts of the rotating shaft becomes relatively thin, reducing the rigidity of the rotating shaft. There is a problem with doing so. The present invention solves the above problems by improving the cylinder section that reciprocates the rotating shaft and by using an electro-hydraulic servo valve.

[Means for solving problems]

For this purpose, the rotating shaft reciprocating device according to the present invention has journal parts 2 formed at both ends, as illustrated in the attached drawings.
The rotating shaft 20 is formed by coaxially forming a cylindrical portion 22 with a larger diameter than the journal portion adjacent to the center side of the rotating shaft 20, and the rotating shaft 20 is reciprocated to some extent in the axial direction via both the journal portions 21. A bearing body 10 is rotatably supported, a pair of hydraulic cylinders 15 are fixed to the bearing body and rotatably fitted in each of the cylindrical parts 22, and pressurized hydraulic oil from a hydraulic unit 1-31 is connected to the bearing body 10. An electro-hydraulic servo valve 30 that alternately switches supply to both hydraulic cylinders 15 to reciprocate the rotary shaft 20 in the axial direction, a reciprocating signal generator 40, and a reciprocating signal generator 40 that controls the amount of movement of the rotary shaft 20 with respect to the bearing body lO. By inputting the displacement detector 45 for detection, the drive signal from the reciprocating signal generator 40, and the feedbank signal from the displacement detection g345, the stroke of the rotating shaft 20 matches the value given by the drive signal. Thus, a servo amplifier 41 is provided to control the operation of the electro-hydraulic servo valve 30.

[Effect]

The drive signal from the reciprocating signal generator 40 is sent to the servo amplifier 41
The electro-hydraulic servo valve 30 reciprocates by switching between supplying pressurized hydraulic oil from the hydraulic unit 31 to the pair of hydraulic cylinders 15 to reciprocate the rotating shaft 20. make it move. The servo amplifier 41 inputs the feedback signal from the displacement detector 45 and operates the electro-hydraulic servo valve 30 so that the reciprocating stroke of the rotating shaft 20 matches the stroke given by the drive signal from the reciprocating signal generator 40. control.

If the frequency of the drive signal from the reciprocating signal generator 40 is changed, the frequency of the reciprocating motion of the rotating shaft 20 will also change accordingly.

〔Effect of the invention〕

According to the present invention, a cylindrical portion having a larger diameter than the journal portion is formed adjacent to the center side of the journal portion formed at both ends of the rotating shaft, and a pair of hydraulic cylinders for reciprocating the rotating shaft are attached to this cylindrical portion. Since they are fitted, it is possible to immediately increase the diameter of the central portion of the rotary shaft supported by the bearing body relative to the journal portion, thereby increasing the bending rigidity of the rotary shaft. In addition, the stroke and frequency of the reciprocating motion of the rotary shaft can be easily changed by simply adjusting the drive signal from the reciprocating signal generator, and the operation of the electro-hydraulic servo valve is controlled by the feedback signal from the displacement detector. This allows the stroke to be set with high precision. Furthermore, only a pair of cylinders are incorporated into the bearing body to provide reciprocating motion, and the only moving part is the rotating shaft itself, simplifying the structure. , the reciprocating signal generator, the displacement detector, etc., can be used as standard products as they are or with only some partial changes, so manufacturing costs can be reduced.

〔Example〕

What is shown in the accompanying drawings is an embodiment in which a reciprocating device for a rotating shaft according to the present invention is applied to a grindstone shaft of a grinding machine that performs vibration grinding. As shown in FIG. 1, a pair of symmetrical bearing metals 11 are coaxially fixed on both the left and right sides of the bearing body 10, and a rotating shaft 20 is attached to the bearing metal 11 with a journal portion 21 formed at both ends thereof. It is rotatably supported through the shaft, and is supported so as to be able to reciprocate to some extent in the axial direction. A hydrostatic bearing supporting the journal portion 21 is formed on the inner circumferential surface of each bearing metal 11, and a hydraulic unisol
-31 is supplied with pressurized hydraulic oil.

A cylindrical portion 22 having a larger diameter than the journal portion 21 is formed adjacent to the center side of each journal portion 21 on the rotating shaft 20, and a central portion 23 having an even larger diameter is integrally formed on the center side thereof. has been done. A mounting flange 25 is fixed to a tapered portion of the rotating shaft 20 at the left end in the figure, and a grinding wheel 27 is screwed and fixed to this mounting flange 25 via a fixing plate 26.

A pulley 28 is fixed to the tapered portion at the right end of the rotating shaft 20, and the rotating shaft 20 is rotationally driven by a drive motor (not shown) via a belt 29.

At the axially inner end of each bearing metal 11, there is an inner peripheral surface 15 that rotatably fits into the outer peripheral surface of each cylindrical portion 22 of the rotating shaft 20.
A pair of hydraulic cylinders 15 are integrally provided. Pressurized hydraulic oil from the hydraulic unit 31 is supplied to each cylinder 15 through a communication passage 32 . Electro-hydraulic servo valve 30. The oil is alternately supplied via the communication passages 33a, 33b and the oil passages 34 formed in each bearing metal 11, thereby causing the rotary shaft 20 to reciprocate in the axial direction. The electro-hydraulic servo valve 30 controls the flow rate and switching of the hydraulic oil flowing into each hydraulic cylinder 15 from the hydraulic unit 31 in accordance with an electric signal input to the solenoid 30a.

As shown in FIGS. 2 and 3, four dynamic pressure pads 16 having stepped portions 16a and 16b are integrally formed on the bottom surface 15b of each hydraulic cylinder 15, and this results in an extremely large bearing clearance. It forms a hydrodynamic thrust bearing. As shown in FIG.
b is arranged so that the lower step part 16a and the higher step part 16b are arranged in this order along the rotational direction of the cylindrical part 22, and as the rotating shaft 26 rotates, it moves in the axial direction so that one of the cylindrical parts 22 becomes the step part. When approaching steps 16a, 16b, step portions 16a, 16b
The dynamic pressure P generated in the cylindrical portion 22 and the step portion 16b is prevented from coming into direct contact with each other. The oil passage 34 that supplies hydraulic oil into the hydraulic cylinder 15 is connected to the dynamic pressure pad 16.
It opens at the bottom surface 15b between the two. In addition, in FIG. 3, the step difference between both step portions 16a and 16b is shown in an enlarged state.

As shown in FIG.
6 is fixed, and a sensor 47 is fixed to the bearing body 10 opposite to this via a bracket 13, and the target 46 and sensor 47 detect the amount of movement of the rotating shaft 20 with respect to the bearing body 10. displacement detector 4
5 is composed. This displacement detector may be of other types, such as a differential transformer type.

The electric servo valve 30 is operated by inputting a drive signal from a reciprocating signal generator 40 via a servo amplifier 41, and selectively supplies pressurized hydraulic oil from a hydraulic unit 31 to each hydraulic cylinder. ing. The reciprocating signal generator 40 has stroke and frequency opening knobs 40a and 40b, and outputs a drive signal (for example, a sine wave signal) with a designated stroke and frequency to the servo amplifier 41. The servo amplifier 41 inputs this drive signal and at the same time inputs the feedback signal from the displacement detector 45 via the amplifier 42, and operates the electric servo valve 30 so that the deviation between these two signals becomes zero. As a result, the rotating shaft 20 reciprocates with the stroke and frequency specified by the reciprocating signal generator 40. The stroke specified by the reciprocating signal generator 40 is equal to or less than the maximum stroke determined by the hydraulic cylinder 15, but if an abnormality occurs in the control system and the stroke increases and the end surface of the cylindrical portion 22 approaches the stepped portion 16b, As described above, since the dynamic pressure P increases, direct contact between the cylindrical portion 22 and the stepped portion 16b is prevented.

As described above, according to this embodiment, the diameter of the center side of the journal portions 21 at both ends of the rotating shaft 20, which is supported by the bearing body 10 via the bearing metal 11, is immediately increased to increase the bending rigidity of the rotating shaft. Therefore, the vibration of the grinding wheel 27 can be reduced and the precision of the grinding surface can be improved. In addition, the stroke and frequency of the reciprocating motion of the rotary shaft 20 can be set easily and with high precision.Furthermore, the structure is simple, and the components such as the electric servo valve 30 can be used as standard products or with some modifications. Since it can be used with only partial changes, manufacturing costs can be reduced.

Note that, as in this embodiment, the hydraulic cylinder 15 is connected to the bearing metal 11.
The structure can be further simplified if the hydraulic unit 31 that supplies hydraulic oil is used in common with both the hydraulic cylinder 15 and the hydrostatic bearing, but the present invention is not limited to this. The hydraulic cylinder may be fixed to the bearing body 10, or a separate hydraulic unit may be provided.

Note that if the reciprocating signal generator 40 is controlled by a numerical control device, it is also possible to give the rotary shaft 20 reciprocating motion with a complicated waveform in addition to simple harmonic motion.

[Brief explanation of drawings]

The accompanying drawings show an embodiment of a reciprocating device for a rotating shaft according to the present invention, and FIG. 1 is an overall configuration diagram including a vertical sectional view of the main parts;
2 is an enlarged cross-sectional view taken along the line ■--■ in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line m--m in FIG. Explanation of symbols 10...Bearing body, 15...Hydraulic cylinder, 20...
...Rotating shaft, 21... Journal part, 22... Cylindrical part, 30... Electric-hydraulic servo valve, 31... Hydraulic unit, 40... Reciprocating signal generator, 41... Servo Amplifier, 45...Displacement detector. Figure 2 Figure 3 I 15...Hydraulic cylinder 21...Journal part 22...Cylindrical part

Claims (1)

[Claims] A rotating shaft formed by coaxially forming a cylindrical portion with a larger diameter than the journal portion adjacent to the center side of the journal portion formed at both ends, and a rotating shaft that is slightly axially moved through the both journal portions. A bearing body is supported for reciprocating movement, a pair of hydraulic cylinders are fixed to the bearing body and rotatably fit into each of the cylindrical parts, and pressurized hydraulic oil from a hydraulic unit is alternately supplied to the hydraulic cylinders. an electro-hydraulic servo valve that reciprocates the rotating shaft in the axial direction by switching supply to the rotating shaft;
a reciprocating signal generator, a displacement detector for detecting the amount of movement of the rotating shaft with respect to the bearing body; A reciprocating device for a rotating shaft, comprising a servo amplifier for controlling the operation of the electro-hydraulic servo valve so that the stroke corresponds to the value given by the drive signal.