RU2382250C2 - Belt-block brake with adjustable pulley - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to machine building field, particularly to belt-block brakes of structural and draw works. Brake contains stationary semi-blocks, brake band, friction elements and mechanical drives. To flange of drum it is rigidly fixed the first semi-block. The second semi-block in its middle part of flange is connected to the first semi-block by means of screws, providing its centering and directional movement ensured by bushing. From the top if bushing perpendicularly to surface of flange it is installed helical spring, pressed from the butt by retainer. Screws and bushing are put on friction and frictionless bearings. Into L-shaped cavities of semi-blocks there are installed friction elements.

EFFECT: there is achieved effectiveness increase of retardation ensured by interaction of surfaces of friction elements with conjugate metallic surfaces of adjustable pulley by means of changing of its width subject to realisable brake power.

3 cl, 4 dwg

Description

The invention relates to mechanical engineering and can be used in tape and shoe brakes of a construction and drilling winch.

Known tape brake shoe winch containing a brake pulley with a working surface, which when braking is covered by a brake band with friction linings. In this case, the tension value of the running (Sн) and running (Sc) branches is characterized by their ratio varying from 2.0 to 10.0 [1, analogue; Alekseevsky G.V. Drilling rigs Uralmashzavod. - M .: Nedra, 1981. - P.132, Fig. 68].

The brake has the disadvantage that it is not possible to adjust and control the braking power in it because of the constant design parameters of the brake pulley.

A two-stage tape-shoe brake is known that contains a brake pulley, brake belt, main friction linings and a drive, and at the same time it is equipped with an elastic brake band-ring resting on disk springs on the pulley flanges, and a U-shaped recess is made along its perimeter. In the U-shaped recess with a gap relative to the side surfaces of the flanges and the working surface of the pulley are the main friction linings that are attached to the brake band-ring. Additional friction linings interacting with the brake belt are attached to the outer surface of the brake band-ring, and the specific loads on the external and internal friction pairs of the friction brake assemblies are the same due to different coefficients of mutual overlap of their interacting surfaces [2, prototype; Russian patent 2224926 C2, class. F16D 49/08, 49/12 for 2004].

The main disadvantage of this brake is that it has a complex structure and high pulley metal consumption.

Compared with the analogue and prototype, the proposed technical solution has the following distinctive features:

- increases the effectiveness of the brake by reducing specific loads on interacting surfaces, and as a result, an increase in the coefficient of friction and ultimately the braking torque;

- the coefficient of mutual overlap of external and internal friction pairs increases due to constant axial preload and variable radial preload of friction elements;

- equalization of specific loads along the perimeter of the external and internal brake friction pairs is achieved due to the successive contact of the friction elements under various branches of the brake band;

- thermal stresses of the brake pulley are reduced due to its division into movable and fixed pulleys, and rings, which reduces the temperature difference between their surfaces;

- a quick change-over of the brake pulley to wide friction elements is carried out by moving its movable pulley and installing an additional pulley between the pulleys, which significantly reduces the braking power;

- A reduction in the vibration of the friction brake assemblies is achieved through the use of an elastic coil spring in a detachable device.

- eliminates the sharp brake band capture of the convex surfaces of the friction elements, and as a result, the shocks and vibrations of the friction pairs disappear due to the presence of a rubber cable under the outer shoe.

The aim of the present invention is to increase the braking efficiency by alternately applying external and internal friction units with the ability to control and control the braking power, changing the width of the brake pulley before starting braking.

This goal is achieved by the fact that in the tape-block brake with a sliding pulley, the first half pulley is rigidly attached to the drum flange, and the second half pulley in its middle part of the flange is connected to the first half pulley by means of special bolts that ensure its centering and directional movement due to the sleeve, on top of which perpendicular to the surface of the flange, a cylindrical spring is installed, pressed from its end by a lock washer; at the same time, special bolts and a sleeve are mounted on sliding and rolling bearings, and friction elements are installed in the L-shaped cavities of the half-cows. The latter are made in the form of separate sectors with external and internal friction linings, which are vulcanized from different sides to the rubber cable, which is the middle line for friction elements. To increase the width of the pulley, a metal ring is installed between its pulleys using pins located on its lateral surfaces, and the outer and inner radii of the ring are equal to the working and non-working surfaces of the rim of the brake pulley.

In Fig. 1, a kinematic diagram of a drawbar brake of a drawworks is shown; in Fig. 2 is a view A from Fig. 1 of a friction brake assembly; figure 3 is a longitudinal section of a tape-shoe brake with a device for moving a half-pulley; figure 4 shows the connection of the plug-in metal ring with the bases of the brake half-claws. In figure 1 and 2, the following conventions are used:

R _W - the radius of the working surface of the brake pulley; ω _W - the angular speed of the brake pulley; F _p - the working force applied to the brake control lever; S _n , S _c - the tension of the running and running branches of the brake belt.

The tape-shoe brake contains a pulley 1, which consists of a fixed 2 and a movable 3 pulleys having 4 holes in their base 5. A fixed pulley 2 in its lower part is fastened by means of bolts 2 to a flange with a hub 7, on which by means of a prismatic key 8 set the drum 9. A rope 10 is wound on the last one. The fixed pulley rests on the lifting shaft 11. The movable pulley 3 is also fastened with bolts 4 to the flange with the hub 12, made in the form of a sleeve on which coil springs are located 13. In this case, the bushings 12 are seated on the rolling bearings 15 through the intermediate sleeve 14, which, in turn, are located on the partially hollow connecting sleeve 16. The latter is attached to the lifting shaft 11 using a stud 17. The cylindrical spring 13 is locked from its end with a special washer 18, which is fastened to the end of the connecting sleeve 16 with a screw 19. The connection of the flanges 7 and 12 of the half-cups 2 and 3 with the help of bolts 20, mounted on the plain bearings 21, and ensures their centering and movement of the half-cup 3 with respect to 2. odvizhnogo polushkiva Polushkivy 2 and 3 at their bases 4 are interconnected bellows 22 which is expanded by moving the movable polushkiva 3, and also prevents the ingress of moisture and deterioration products on the moving surface and mutually sliding surfaces and rolling bearing. The rubber cover 23, in which the sliding device of the half-cup is located 3. serves the same purpose. The half-cups 2 and 3 are easily dismantled by unscrewing the fixing bolts 6 and replaced if necessary with half-cups with a large rim width. To increase the width of the brake pulley 1, a ring 24 is also used, which with its pins 25 is installed in the holes 5 made in the base 4 of the half pulleys 2 and 3.

Friction elements 26 are located on the brake pulley 1, consisting of upper 27 and lower 28 linings. The latter are vulcanized to the rubber band tape 29. Friction elements 26 are made in the form of sectors. On top of the friction elements 26 interact with the working surface 30 of the brake tape 31. The latter has a ramp up and run down II branches with tension S _n and Sc. The oncoming branch I of the brake band 31 is connected to the brake control lever 32.

Tape-brake brake with a sliding pulley refers to two-stage brakes. The first stage consists of external friction pairs ("working surface 30 of the brake belt 31-outer surfaces of the friction elements 26") brakes. The second stage consists of internal friction pairs ("internal surfaces of the friction elements 26-working surface of the brake pulley I") brakes.

Before the tape brake with a sliding pulley is operating, its friction units are evaluated for braking power, which depends on changes in sliding speed (V), friction force (F _T ) and dynamic coefficient of friction (f)

_{P T = f · F T ·} V

Specific braking power is estimated by the expression

,

,

where A ₀ is the total area of the interacting friction surfaces.

When working external friction pairs A ₀ = A _vn + 2A ₁ , where A _vn is the interaction surface of the brake belt with the outer surface of the external friction lining; 2A ₁ - the interaction surface of the side surfaces of the friction element with the inner surfaces of the pulley flanges.

In operation, the internal friction pairs A = A ₀ + A _{w1 to w2} + A, where A _{w1, w2} A - surface interaction between the working surfaces of the first and second polushkivov and the working surface of the cylindrical rings with the working surface of the friction element.

Thus, from the required specific braking power of the tape-shoe brake, the width of the rim of the brake pulley is selected based on the condition that the width of the half pulleys is constant and the width of the metal ring is a variable.

The tape-block brake with a sliding pulley is characterized by two braking modes.

In the first braking mode, when a working force is applied to the brake control lever 32, the working surface of the brake belt 30 interacts with the outer surfaces of the upper plates 27 of the friction elements 26. As the tension of the running branch I of the brake belt 31 increases, this interaction will continue until the resistance of the interaction of the side surfaces of the troughs of the half-shells 2 and 3 with the side surfaces of the friction elements 26 (under the influence of the axial a spring 13 applied to the flange 12 of the movable half pulley 3) and the inner surfaces of the friction elements 26 with the working surfaces of the half pulleys 2 and 3, as well as a metal ring 24 installed between them (are under the action of the normal force created by the brake band 31). In other words, the displacement of each sector friction element 26 will occur if the dynamic coefficient of friction of the external friction units becomes greater than the reduced static coefficient of friction above the listed interaction surfaces. On this, the first braking mode ends.

In the second braking mode, the tension of the running branch I of the brake tape 31 increases and its working surface 30 adheres to the outer surfaces of the friction elements 26 that are under it. At this time, all the other frictional elements 26, moving along the working surface of the half pulleys 2 and 3, as well as the metal ring 24, try to get under the runaway branch II of the brake belt 31, thereby resisting the rotation of the pulley 1. At the end of the second braking mode, the belt 31 clamps the friction elements 26 that fall under it and the pulley 1 stops along with the drum 9 and the winding rope 10 remaining on it.

The technical result is to increase the braking efficiency due to the interaction of the surfaces of the friction elements with the mating metal surfaces of the sliding pulley by changing its width, taking into account the braking power realized.

Information sources

1. Alekseevsky G.V. Drilling rigs Uralmashzavod. - M .: Nedra, 1981. - P.132, fig. 68 [analogue].

2. Patent of Russia 2224926 C2, cl. F16D 49/08, 49/12, BI No. 6 for 2004 [prototype].

Claims (3)

1. Tape-brake brake with a sliding pulley containing fixed half-pulleys, brake band, friction elements, mechanical drives, characterized in that the first half-cup is rigidly fixed to the drum flange, and the second half-cup in its middle part of the flange is connected to the first half-cup by special bolts ensuring its centering and directional movement due to the sleeve, on top of which a cylindrical spring is installed perpendicular to the flange surface, pressed from its end by a lock washer, while m special bolts and bushings are mounted on sliding and rolling bearings, and friction elements are installed in the L-shaped cavities of the half-cows. 2. The tape-brake brake with a sliding pulley according to claim 1, characterized in that the friction elements are made in the form of separate sectors with external and internal friction linings, which are vulcanized from different sides to the rubber cable, which is the middle line for friction elements. 3. The tape-brake brake with a sliding pulley according to claim 1, characterized in that in order to increase the width of the pulley, a metal ring is installed between its pulleys using pins located on its side surfaces, and the outer and inner radii of the ring are equal to the working and non-working surfaces of the rim brake pulley.

Images