JPS61194328A - Load apparatus - Google Patents

Abstract

PURPOSE:To apply ultra-low speed repeating load with high accuracy, by applying rotary driving to a double nut limited in the movement to the axial direction by a motor and moving a screw rod shaped load rod limited in rotation to the axial direction. CONSTITUTION:When a worm 22 is rotated to integrally rotate a nut holder 9, a clamp flange 7 and a double nut 5. In this case. because a flange part 9a is held between thrust bearings 17, 17' being nut movement limiting means, the double nut performs only rotary motion. By this mechanism, the load road 4 limited in its rotation by a rotation stop jig 35 is moved up and down in the axial direction through a ball screw to apply load to a test piece S. By reversing the rotary direction of the motor, repeating load can be applied to the test piece.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a loading device suitable for use in applying repetitive loads in fatigue tests of materials and the like.

(Prior Art) Currently, hydraulic actuators using servo valves are the mainstream as load actuators incorporated in fatigue testing machines.

(Problems to be Solved by the Invention) However, the conventional hydraulic actuator described above was developed for high-frequency fatigue tests with relatively high loading speeds, and it is difficult to control minute amounts of oil using a servo valve. Therefore, there was a problem in that testing under ultra-low speed loads was generally impossible.

In addition, it requires time and effort to prevent foreign matter from entering the hydraulic system and to control oil temperature, and there is also the problem that the hydraulic pump is quite noisy.

(Means for Solving the Problems) The present invention provides a solution to the above-mentioned hydraulic actuator.
In order to solve this problem and enable repeated loading at extremely low speeds, we adopted the configuration described below.

In other words, the load device according to the present invention includes a threaded load rod and a double nut that are screwed together by a pole screw, a motor for rotationally driving the double nut, a worm gear type reducer that transmits the rotation of the motor to the double nut, and a double nut. The double nut is provided with a movement restricting means for restricting movement in the axial direction during rotation, and a rotation prevention device for restricting rotation of the load rod during rotation of the double nut and allowing only MJl& in the axial direction.

(Operation) When the motor rotates, its rotational motion is transmitted to the double nut via the worm gear reducer.

Rotate the double nut at low speed. Therefore, the load rod screwed into the double nut moves in the axial direction while its rotation is restricted, and applies a load to the test piece.

(Example) Fig. 1 shows an example of a loading device according to the present invention.
It is used by attaching it to.

A vertical load rod 4 with a ball screw provided on the outer periphery is provided in the core of the housing 3 with load *1ill, and a double nut 5 preloaded with this is screwed into the load rod 4 by the ball screw. The double nut 5 has a flange portion 5a at its upper end, and has a 7-lunge l! 1l15a is
Bolt 8, 8. . . is held between the flange 7 and the nut holder 9. An upper cover 11 and a lower cover 13 are fixed to the opening at the upper end of the housing 2 and the opening at the lower end, respectively, with bolts.

This load device all has mounting bolts 8, 8, . It is attached to the testing machine by... The cylindrical portion 7a provided in the core of the tightening flange 7 is connected to the through hole 11a provided in the core of the upper lid 11.
A radial bearing 15 is inserted between the outer circumferential portion and the inner wall of the through hole 11a. The nut holder 9 has a cylindrical shape as a whole, and has a flange portion 9 at the upper end.
a, and the portions below it are, in order, the support portion 9b and the gear fixing portion 8C1 extension portion 8d. A radial bearing 15' similar to that described above is interposed between the lower end of the support portion 9b and the inner wall of the housing 3.

Further, both upper and lower surfaces of the flange portion 9a of the nut holder 9 are
Thrust bearing 17.1? 'is held by. Note that the nut holder 9 has a negated portion 9e formed on the intermediate inner surface that does not contact the double nut 5, and the multi-lead worm wheel 20 of the multi-lead worm gear type reducer 19 is fitted into the gear fixing portion 9C of the nut holder X9. equipped,
Pol) 21, 21. It is fixed by... Further, the nose ring 3 is provided with a first chamber holding section 3a, and a plurality of chambers 22 are housed inside this section. The worm 22 and the worm wheel 20 may be aligned with each other.

The fixing position of the worm wheel 20 is adjusted by a shim 24 so that its center line and the axis of the worm 22 coincide. A large pulley 24 is attached to the shaft of the worm 22, and this large boolean 1J24 is connected to a small pulley 27 attached to the rotating shaft 2111a of the motor 2B installed below and the belt 2.
They are connected by 9. The motor 28 is connected from the reference oscillator 30 to the servo amplifier 3! It is a DC servo motor that is activated by a signal supplied through the servo motor.

The upper part of the load rod 4 is the tightening bolt 7 and the upper cover! The table 2 passes through the hole 2a drilled in the table 2
It protrudes from the top surface. A sliding cap 28 is fitted to the upper end of the load rod 4, and this cap is slidably fitted to a guide ring 32 fixed to the table 2.

Further, a concentric auxiliary shaft 33 is connected to the lower end of the load port and the door 4 by bolts 34, 34, . . . The stopper 35 is a cylindrical fitting 37 with two flange, and the bolt 3
A core 0 end 43 of a differential transformer 42 is fixed at a position in the middle of the 0-turn stopper 35, which is fixed by a pin 40 or the like, at a position slightly closer to the tip. Furthermore, a shaft 4B that supports a guide roller 45 is provided protruding from the tip of the rotation stopper 35.

A guide rod mounting plate 50 is provided on the lower cover 13 of the housing 3.
51, 51. It is fixed by...

A coil holder 53 that holds the coil 44 of the differential transformer 42 is fitted onto the guide rod mounting plate 50 and fixed with bolts. A vertical guide rod 55 is attached to an end of the guide rod attachment plate 50. The guide rod 55 is provided with a pair of limit switches 511, 5?, vertically spaced apart from each other. are attached by respective supports 58 and 59, and these limit switches 511
．． The guide roller 45 is supported at an intermediate portion of the guide rod 57 so as to be in contact with the guide rod 55 and rotate. The limit switches 511, 57 are for regulating the movement range of the load rod 4, and stop the motor 2B when the tip end 48a of the shaft 4B of the guide roller 45 comes into contact.

The inside of the housing 3 of this load device 1 is filled with lubricating oil up to the level of the upper surface of the worm wheel 20, so an oil seal is provided in the lower lid 13 to prevent oil leakage. A BO and an O-ring 81 are provided. In addition, there is an oil drain hole 8 for draining oil at the appropriate location on the lower lid.
3 are provided.

The through hole 50a provided in the guide rod mounting plate 50 is closed by a plug 84 housed in the through hole 50a.

When this load device tt is used, when a signal emitted from the reference oscillator 30 is supplied to the servo amplifier 31, the signal causes the DC servo motor 2B to rotate in either the forward or reverse direction. When the motor 2e rotates, the belt 29
Since the worm wheel 22 is rotated through the worm wheel 22, the worm wheel 20 that meshes with the worm wheel 20 rotates, and the nut holder 9 is rotated.
．． Tightening is done by rotating the flange 7 and double nut 5 as one unit. In this case, the flange portion 8a of the nut holder 9 is connected to the thrust bearing 17. which is the nut movement regulating means.
17', the double nut 5 does not move in the axial direction, but performs only rotational movement.

When the double nut 5 rotates in a fixed position, the load rod 4 is threadedly engaged with it via a pole screw.

It moves up and down in the axial direction depending on the rotation direction of the motor.

In this case, since the rotation of the load rod 4 is restricted by the one-turn stopper 35, it moves only in the axial direction and applies a load to the test piece attached to the testing machine. By changing the direction of rotation of the motor, the load rod can be moved up and down in reverse. When the load rod 4 moves up and down, the rotation stopper 35 also moves together, and the amount of this movement is detected by the differential transformer 42.

This detection signal is fed back to the servo amplifier 31, so that the direction and amount of movement of the load rod 4 are correctly controlled as instructed by the reference transmitter 30.

This load device 1 does not use a hydraulic pump or a hydraulic valve, so it generates very little noise.

The running cost is low when used as a load device for long-term fatigue tests, and since the drive unit uses a precision ball screw with extremely low backlash and a multi-lead worm gear type reduction device, the Ultra-low speed repetitive tests can be performed without problems such as time delays and waveform disturbances during one reversal. A servo motor is used as the drive source, and the worm gear reducer is driven by a servo method that constantly reduces the difference between input and output signals to 0.
Accurate driving conditions can be maintained at all times.

(Effect) As is clear from the above explanation, 5 Loads on the present invention 4
IcIi has become an excellent product with low noise, easy maintenance, and the ability to apply repeated loads at extremely low speeds with high accuracy.

[Brief explanation of the drawing]

1 and 2 are a front sectional view and a side view of an example of a load device according to the present invention.

Claims (1)

[Claims] (1) A threaded load rod and a double nut screwed together by a ball screw, a motor for rotating the double nut, a worm gear reducer that transmits the rotation of the motor to the double nut, and a shaft when the double nut rotates. A load device comprising a movement restricting means for restricting movement in the direction, and a detent device that restricts the rotation of the load rod when the double nut is rotated and allows movement only in the axial direction.