RU2687296C1 - WEIGHTLESS CALIBRATION SYSTEM OF FIRST RATE WITH RANGE OF STORAGE AND TRANSMISSION OF UNIT FROM 1 kN TO 1000 kN WITH LIMIT OF ALLOWABLE VALUES OF 0,02 PERCENT NOMINAL ACCUMULATED ERROR - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to the working standards of the unit of power of the 1st category (GOST 8.640-2014). Machine consists of a loading device designed to transfer units of force to working standards of the 2^nd category (portable dynamometers) and working measuring instruments (dynamometers, load sensors) and a system for measuring force and controlling the loading device. Loading device of the machine includes: fixed frame formed by the base, fixed beam and two smooth columns rigidly connected to the base and fixed beam; movable traverse with a “reference” set thereon, located between the base and the fixed traverse; two worm-screw gearboxes fixed at the base symmetrically with respect to the central axis of the loading device, interconnected by a cross-shaped coupling; servomotor that drives a movable traverse through worm-screw gears using ball screws mated with nuts fixed in the movable traverse body; two linear bushings fixed in the body of the mobile beam, with the help of which the beam is guided along the columns of the fixed frame; fixed frame formed by two columns rigidly connected with the crosshead and the base, located along the axis of the loading device between the running screws at an angle to the horizontal axis of the base; reverse frame formed by the upper and lower traverses rigidly connected by two columns passing through the holes in the movable traverse by the traverse of the fixed frame and located along the axis of the loading device in the plane of the ball helical columns in such a way that between the lower crosshead reversing frame and a traverse of the fixed frame, a compression zone is formed, and between the lower traverse of the reverse frame and the base of the machine is the stretching zone for placing the “measuring instruments” being checked. Measurement system includes secondary devices "standard" and verifiable "measuring instruments." Control system includes a controller that controls the speed of rotation of the servomotor for a given program, as well as in manual mode.

EFFECT: technical result is simplified design.

1 cl, 1 dwg

Description

DESCRIPTION OF THE INVENTION

The power-producing machine of the first discharge with a range of storage and transfer units from 1 kN to 1000 kN with the limit of permissible values of the confidence limits of the relative total error of 0.02%.

The invention relates to the working standards of the unit of force of the 1st category (GOST 8.640-2014), intended for the transfer of units of force by the method of direct measurements by the working standard of the 2nd category (portable dynamometers) and the working tool of measurement - dynamometers, load sensors ").

GOST 8.640-2014 provides, according to the principle of operation, the following working standards of the 1st category with the limit of the range of storage and transfer of a unit up to 1 MN and a total error of 0.02%:

- installation of direct loading;

- force-multiplying installations and machines of hydraulic or lever type;

GOST also allows for force-reproducing machines that have other principles of action. According to the principle of operation, the claimed machine belongs to the machines with seromechanical loading, i.e. for machines with other principles of action (note to table 2 GOST 8.640-2014).

Known power-generating machine of the hydraulic type MOS-2-500 / 500K, corresponding to the state verification scheme for means of measuring force according to GOST 8.065-85 (annulled, replaced by GOST 8.640-2014) and intended for calibration and calibration of exemplary portable dynamometers of the 3rd category GOST 9500-84, working dynamometers and force sensors.

According to metrological characteristics, this machine does not meet the working standards of the 1st category in accordance with GOST 8.640-2014 and cannot be an analogue of the claimed machine.

Of the known force-reproducing machines, the MSV-MG4 machines produced by the SKB Stroypribor Chelyabinsk can be an analogue of the claimed machine. Machines comply with the requirements of GOST 8.640-2014 to the working standards of the 1st category.

The machine consists of a power frame with a loaded sealed hydraulic cylinder mounted on the frame traverse, and a control cabinet. A replaceable reference force sensor is installed on the hydraulic cylinder piston, on which a four-column reverser is freely suspended. The machine is equipped with two hydraulic cylinders for raising and lowering the reverser to change the reference force sensor.

The principle of operation of the machine is based on a comparison of the output signals of the reference force sensor and the calibrated measuring instrument while simultaneously loading them with the same force.

The stretch zone is located at the bottom of the frame, the compression zone is in the middle. The height of the space in the areas of tension and compression is not adjustable: spacers and adapters are used for different sizes of calibrated measuring instruments.

In the control cabinet there is a pumping unit, feeding the loading cylinder through a non-return valve, and a small sealed hydraulic cylinder, the piston of which is driven by an electromechanical servo drive. The working cavity of the small hydraulic cylinder is connected directly to the working cavity of the loading hydraulic cylinder.

The pumping unit is used for sampling gaps and coarse loading, a small cylinder - for precise, controlled change in load and maintaining it with the necessary accuracy.

This complication of the loading scheme is due to the fact that with a total error of 0.02% on a machine, for example, an MSV-500MG4 with a reproducible force range from 10 kN to 500 kN, it is necessary to ensure the accuracy of stopping and holding the force on the first reference point within 2 N. Servohydraulics with a running pump cannot provide such accuracy.

Therefore, approaching the reference point and holding the reproducible force with the required accuracy is carried out by the small hydraulic cylinder using an electromechanical servo actuator that moves the piston of the small hydraulic cylinder when the pump unit is turned off.

The machine is completed with a secondary transducer and software produced by SKV Stroypribor LLC.

The disadvantages of the prototype include the lack of regulation of the height of the working space in the areas of tension and compression, in connection with which the machine is completed with a set of spacers and adapters, and the complexity of the control system - the presence of two loading cylinders and, accordingly, two control systems, as well as two hydraulic cylinders for lifting and lowering the four-column reverser.

The inventive machine, these shortcomings are absent

The attached diagram shows the loading device of the inventive machine, which includes the following parts and components:

- two worm-screw gearbox 1, fixed to the lower plane of the base 2 symmetrically with respect to the axis of the loading device, interconnected by a coupling 3, the driving screws 4 of which are driven in rotation by the servo motor 5 through the worm gears 6;

- movable yoke 7 with nuts 8 fixed in it, mated with ball screws 4, and linear bushings 9 mated with guide columns 10 rigidly connected to base 2 and fixed beam 11 with nuts 12;

- reverse frame, consisting of the upper 13 and lower 14 traverse, rigidly connected by columns 15 with nuts 16 and forming with the base 2 a zone of verified “measuring instruments” of tension;

- a fixed frame consisting of a yoke 17, rigidly connected with the help of columns 18 and nuts 19 with the base 2 and forming with the reverse frame an area of verifiable “means of measurement” of compression;

- limiters 20 reverse frame, mounted on columns 18 with clamps 21;

- strips 22, centering the reversing frame in the initial position;

- vibrosupport 23 loading device;

- replaceable strain gauge compression force sensor 24 ("standard");

- verifiable measuring instrument 25.

The inventive machine works as follows.

The transfer of the unit of force to the “measuring device” to be verified (working standards of the 2nd category, etc.) is carried out on the machine from a strain gauge of compression force 25 (hereinafter referred to as the “standard”) with a limit of permissible values of the confidence limits of the relative total error not more than 0.02%, located in the same power circuit with a verifiable "measuring instrument". "Standards" - replaceable. The limit of measurement of each replaceable "standard" corresponds to the limit of measurement of the “measuring instrument” being verified. "Standard" is installed on the movable yoke 7 into the space formed by the movable yoke 7 and the upper yoke 14 of the reverse frame. In the initial position, the reverse frame rests on the stops 20 fixed on the columns 18 of the fixed frame, while in the compression zone the maximum height of the working space is formed, in the extension zone the minimum height. The traverse is moved with the help of a servomotor 5 with a large range of rotational speed control (r / min).

The servo motor 5 through the worm gears 6, built into the gearboxes 1, rotates the ball spindle screws 4, which, interacting with the nuts 8, fixed in the body of the cross member 7, move it up and down.

When the traverse is moving, it is guided with the aid of ball bushings 9 along smooth columns of a fixed frame formed by a base 2, a fixed traverse Neither two columns 10, nuts 12 rigidly fastened to them.

The order of the car.

1. Installation of the necessary height of the working space in the zones of tension or compression for the “measuring instruments” being checked is carried out at idle. To do this, the movable traverse with the established “standard” moves up to the closing of the “reference” with the reverse frame, after which the reverse frame moves with the movable traverse 7, while the height of the working space in the compression zone decreases, and in the stretch zone it increases.

2. Installation of the verified “measuring instrument” on the machine. The attached diagram shows the working standard of the 2nd compression category (portable dynamometer).

3. Move the yoke 7 up at idle speed until the calibrated dynamometer closes with a fixed frame.

4. After closing, the loading of the calibrated dynamometer and the “standard” starts at minimum speeds of rotation of the servomotor 5 (working stroke) with stops at reference points on the forward and reverse (if necessary) strokes.

At stops, the readings of the "standard" and the calibrated measuring instrument are verified.

The invention consists in the following:

1. The adjusting and working stroke of the movable traverse is carried out from a servo motor with a large range of rotation speeds (rpm) adjustment: the adjusting stroke and the clearance of gaps are carried out at maximum rotation speeds, the loading of the standard and the “measuring instrument” being checked and the load on the reference points - on minimum.

This part of the invention in comparison with the analog is especially effective:

- the height of the working space in the zones of tension and compression is regulated - for the analog in the zone of tension it is adjusted manually with a screw, in the zone of compression it is not adjustable;

- lack of hydraulics - a pumping unit and two cylinders are present alongside the analogue, along with a servomotor with a mechanical drive;

- one control system instead of two for analog.

2. The reverser frame is fixed in the initial position by the stops mounted on the columns of the fixed frame.

In the analog, the reverse frame rests on the plungers of the two cylinders, with the help of which the frame is raised and lowered when interchangeable standards are installed.

This part of the invention greatly simplifies the design - the absence of cylinders and the control hydro and electrical equipment.

Claims (2)

1. A force-reproducing machine of the first discharge with a storage and transfer unit range from 1 kN to 1000 kN with a limit of permissible values of the confidence limits of the relative total error of 0.02%, including a loading device containing a base and a fixed traverse, rigidly interconnected by two smooth columns, on which by means of a servomotor and two worm-screw gears a movable traverse moves, a fixed frame containing a traverse rigidly connected to the base by two columns, a reverse frame containing the upper and lower traverse, rigidly connected by two columns passing through the holes in the movable traverse, and forming between the lower traverse and the base a zone of verified “measuring instruments” of tension and between the lower traverse and traverse of the fixed frame a zone of verified “measuring instruments” of compression, replaceable a standard strain gauge force sensor mounted on a movable cross-beam and located in the same power circuit with a verifiable "gauge", as well as including a control and measurement system that differs by the fact that the installation and stroke moving crosspiece, and securing force at the fixed points by means of a servomotor with a large range of rotation speeds. 2. A force-reproducing machine of the first discharge according to claim 1, characterized in that the initial position of the reverse frame is fixed with the help of restraints fixed on the columns of the fixed frame.

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