Band-shoe brake of draw works with gang friction assemblies

FIELD: machine building.

SUBSTANCE: invention relates to machine building, particularly, to draw works band-shape brakes. Proposed brake comprises brake pulley on the shaft and extra brake band with friction discs and the main brake band arranged there under and brake control drive. Extra brake band is secured by friction fasteners with friction surfaces to the main brake band while their leading edges are secured to rocking beam and to crankshaft crank pins. At braking by expansion of brake bands and contact interaction between their surfaces at sliding angles on the side of leading edges of the main and extra brake bands that bring about friction contact forces to cause difference in band tensions, to decrease irregularity of distribution of specific loads in friction pairs "friction disc - pulley". Extra rest friction force originates owing to the main brake band rounding of idle surfaces of brake shoes.

EFFECT: decreased irregularity of distribution of specific loads in friction pairs "friction disc - pulley".

7 dwg

The invention relates to mechanical engineering and can be used in the tape-drum brakes drilling winches.

Known tape-drum brake in which to ensure uniform wear of the friction linings of the latter are located on the working surface of the brake pulley and is provided with an elastic elements connecting them together and banana to the working surface of the pulley, and the dynamic coefficient of sliding friction between the outer surface of the lining and the inner surface of the brake belt is greater than that between the working surface of the lining and the brake pulley [1, similar]. The disadvantage is that you must have friction materials with different dynamic coefficients of sliding friction for the outer and inner surfaces of the plates.

In addition, the brake band is exposed not only dynamic, and thermal loads.

Famous band-Shoe brake with movable friction linings, which contains a separate stationary pads at the beginning of the incoming branch of the brake bands, in the middle of the tape and at the end of the cascading branches of the tape and between the fixed plates are moving pads, which in its upper part by their width have openings planted in the l-shaped grooves of the tape, with movable pads have who is very useful move relative to the inner surface of the tape and the working surface of the pulley, and rolling and cascading branches tape is different in the number of moving plates that are connected together with springs of different stiffness [2, prototype]. The disadvantage is that in the interaction of the outer movable friction lining to the inner surface of the brake belt is not implemented large factor of their mutual overlap.

The proposed solution in comparison with analogue and prototype has the following distinctive features:

the main brake band has a large podatlivosti by reducing its thickness and absence in her body stress concentrators;

- the use of the surfaces of the primary and secondary brake bands, the outer surfaces of the friction lining and the inner surfaces of the friction fasteners brake bands as additional areas of the contact friction;

- no cascading branches on the brake the tape, but the presence of composite brake tape two incoming branches that will substantially reduce their ratio, tension, i.e. S_H1/S_H2(where S_H1, S_H2the tension of the incoming branches of the primary and secondary brake bands);

- the use of contact friction between the primary and secondary brake belts to reduce the difference between the forces of tension is x plots and, as a consequence, eliminating the uneven distribution of unit loads across the width of the friction lining.

The objective of the invention is improving the efficiency of the brakes for the purposeful use of primary and secondary brake belt under tension if each of them only one incoming branch, and the use of additional zones of interaction to obtain multi-pair of friction during braking.

This objective is achieved in that the additional brake band with a friction fastening elements with friction surfaces attached to the brake master tape, and the incident ends attached respectively to the balancer and crank crankshaft necks, while in the process of braking due to stretching of the brake bands and emerging between their surfaces friction contact on the slip angles from the incident ends of the primary and secondary brake bands contact friction, causing decrease of the difference of the forces of tension plots brake belts to help reduce the uneven distribution of unit loads in pairs of friction pads - pulleys, and also due to the rounding the inner surface of the main brake band outside surfaces of the friction lining, leading to the emergence to anitelea the force of static friction.

Figure 1 shows the kinematic diagram of the drawworks with band brake Shoe; figure 2 is a kinematic diagram of the belt-plate brake with multi-pair by friction; figure 3 is a transverse section of figure 2 along a-a; figure 4 shows a view B figure 2 - mounting the primary and secondary brake bands with friction fasteners; figure 5 shows the plot of the additional brake bands; figure 6 - composite brake band with the sprung snatch devices with serial friction lining; figure 7 shows the scheme of pre-bias of the second kind the main brake of the tape relative to the additional brake belt.

Following symbols are used: R_WD_W- the radius and the diameter of the working surface of the brake pulley; r is the radius of the crank of the crankshaft; ω - angular speed of rotation of the pulley; φ, α angles of circumference one and all the overlaps of the working surface of the brake pulley; S_H1, S_H2the tension of the incoming branches of the primary and secondary brake bands; F_Pthe force applied by an operator to the control lever brake; q - force compression of the primary and secondary brake bands on the angle of circumference length l; l⁼l_W1+l_n+l_W2; l_W1, l_W2- the length of the sections of the ribbons on the corners of their sliding α_W1and α_{W2/sub> ; ln- the length of the sections of the ribbons on the angle of repose αn; qƒ - contact force of friction between the cooperating surfaces of the primary and secondary brake bands; h1h2the thickness of the primary and secondary brake bands; P* Pbithe force of interaction that occurs between the primary and secondary brake bands in the i-th their sections 1-1, 2-2, etc.}

According to the kinematic diagram (see figure 1) friction lining 3 is installed on the brake bands 2 that one end (by cascading branches tape) is attached to the balancer 11 and the other (by rolling its branches) to crank necks 6 and 9 of the crankshaft 10.

Serial tape-plate brake drawworks work as follows. The handle 1 is the rotation of the crankshaft 10, in which the driller pulls the brake belt 2 with the friction plates 3 and they sit down on the brake pulley 4. The process of the brake band brake Shoe (see figure 1) is characterized by the following stages: initial (first), intermediate (second) and the final (third). Stop at each of the stages separately.

At the initial stage of the brake friction lining 3, placed in the middle part of the brake bands 2, interact with the working surface of the brake pulley 4. Front interaction is the major extends in the direction of the friction lining 3 incident branches of brake bands 2.

Intermediate stage of braking is characterized by further propagation of the front of the interaction in the direction of the friction lining 3 cascading branches of brake bands 2.

The final stage of braking is characterized by the fact that almost all of the fixed plates 3 brake bands 2 interact with the working surface of the rotating pulley 4. During snubbing the sequence of occurrence of the friction surfaces in contact is repeated. Full cycle braking ends with a stop brake pulley 4 and the drum 5. The brake control drawworks shall also undertake the supply of compressed air through the valve 7 driller in the pneumatic cylinder 8, the piston rod of which is connected to one of Motulevich necks 6 of the crankshaft 10 of the brake. The pressure of the compressed air in the pneumatic cylinder 8 regulate the rotation of the crane 7 driller.

Uneven wear of the friction lining 3 installed on the tape 2, the balancer 11 at the time of deceleration deviates somewhat from the horizontal position and aligns the load on cascading branches of brake bands 2, while providing a uniform and simultaneous girth they brake pulley 4. Thanks to the ball joint implementation loads from the brake bands 2 to the balancer 11 is not changed.

The weakest link in the brake node are friction NAC is ADCI. They are manufactured as separate parts, which can be fastened in various ways (for example, using bars) relative to the flexible steel tape. When installing the ribbon plates with constant pitch their number is always even(12; 16; 18; 20; 22; 26).

Band-Shoe brake drawworks with multi-pair nodes contains friction composite brake tape, which consists of a core 12 and an additional 15 brake bands. Brake master tape 12 with its incident ends are attached to the crank necks 6 and 9 of the crankshaft 10, and lapping the ends of the additional tape 15 is attached to the balancer 11. The main brake band 12 has an outer 13 and the inner surface 14. Additional brake band 15 with its inner surface 16 has sides longitudinal grooves 17 of the same cross section and length. In addition, on the sides of the additional brake bands 15 are rectangular cut-outs 18, which is inserted into a plastic 19 and metal 20 fasteners. Last connect the main 12 and 15 additional brake tape between them.

In the middle of each of the grooves 17 additional tape 15 wound the tabs of the mounting plates 21, which are reinforced by a wire 22 in the body serial friction linings 23 having an outer 24 and 25 working surface. The fastening elements 19 and 20 are the two who are limiters when moving serial friction linings 23 relative to the surfaces of the composite brake belt.

For tripping composite brake tape after braking are sprung snatch device 25, which is attached to the additional brake the tape 15.

Installation of composite brake belt is as follows. From the incident end of the brake master tape 12 is detached fastening lug (figure 6 not shown)that is attached to it using a bolted connection. Then by pressing a friction fastening elements 19 and 20 connect the tape 12 and 15. Then additional brake the tape 15 with the plates 21 are attached serial friction lining 23. The end of the additional brake bands 15 abuts against the end face of the fixing lug brake master tape 12, and the end of the brake master tape 12 abuts against the end face of the fastening eyelet additional brake bands 15.

Thus, in the composite brake tape implement the principle unloading brake master tape 12 by removing from her body stress concentrators (holes: under rivets for fastening the spacer strips for straps; for fixing the resilient rings snatch devices; longitudinal grooves under the mounting strap overlays). This increases the total deformation of the rolling main branches 12 and 15 additional brake bands and, consequently, will S_H1-S_H2pain is e, i.e. the friction force on the interacting surfaces and the generated braking torque. This provides good flexibility brake master tape 12 when the regulated factor of safety.

Additional brake band 15 provides fastening serial friction pads 23, and the gap between the pairs of friction "cover - pulley" by attaching to it a spring snatch device 26.

Composite brake band carries only the weight load from the serial of the friction lining 23. It is necessary to take into account the fact that the thickness of the composite brake bands does not exceed the thickness of the brake serial tape.

During operation of the tape-plate brake drawworks with multipair the friction nodes have the following areas of cooperation: "the outer surface of the additional brake bands 15 - surface friction fasteners 19"; "the inner surface 16 of the additional brake belt 15 to the outer surface 13 of the main brake bands 12"; "the inner surface 14 of the main brake bands 12 - surface friction fasteners 19"; "the inner surface 14 of the main brake belt 12 to the outer surface 24 of the friction pads 23"; "working surface 25 of the friction lining 23 - working surface of the brake pulley 4".

The condition is eat health in the resulting friction pairs with almost immobility serial friction lining 23 is the following. Dynamic coefficients of friction in the friction nodes: "working surface of the brake pulley 4 - working surfaces 25 pads 23"; "the inner surface 14 of the main brake belt 12 to the outer surface 24 of the plates 23" should be the same. For this purpose, the purity of the 13 outer and inner surfaces 14 of the main brake belt 12 should be the same as the surface of the brake pulley 4. In addition, the outer surface 24 of the plates 23 must be machined so that the microgeometry was the same with the micro geometry of their working surfaces 25. As for the contact friction between the outer surface 13 of the main brake belt 12 and the inner surface 16 of the additional brake belt 15, it is important to note the following. According to Fig.7. when the circuit brakes within the zones of slip occurs a displacement of the brake bands, the base 12 relative to the additional 15 due to the fact that S_H1/S_H2≥1,0, commensurate with the tensile deformations brake bands. Let's call it pre-bias of the second kind. Between zones slip l_SCis a zone of complete rest l_nwithin which the core 12 and an additional 15 tape equally spaced out and did not move, which is true when h₁>h₂. When before aeternam the offset of the second kind the length of the zones of the elastic displacement l _W1and l_W2depends on the tension of the S_H1that forces the contact friction between the outer surface 13 of the main brake band 12 and the inner surface 16 of the additional brake band 15, as well as on the ratio of the rigidity of the elastic primary and secondary brake bands. Denote the stiffness of the main brake bands 12 - c_nand an additional 15 - c_in.

From the equilibrium condition of the tape width b within the lower zone of the slide l_W1should

$$\begin{array}{l}{P}_n{2}_{}=S_{H1}-qƒl_{\mathrm{with\; a}K1}b;\\ P_{\mathrm{in}}{2}_{}=qƒl_{\mathrm{with\; a}K1}b;\end{array}\}(1)$$

From the system of equations (1) we get

$$\frac{P_{n2}}{P_{\mathrm{in}2}}=\frac{S_{H1}-qƒl_{\mathrm{with\; a}K1}b}{qƒl_{\mathrm{with\; a}K1}b}.(2)$$

Moving tapes and their elongation in the cross-section 2-2 will be the same as this section is located at the beginning of the zone of peace l_n. Then

$$P_{n2}={\mathrm{with\; a}}_{n}u;P_{\mathrm{in}2}={\mathrm{with\; a}}_{\mathrm{in}}u.(3)$$

From equations (3) should

$$\frac{P_{n2}}{P_{\mathrm{in}2}}=\frac{{\mathrm{with\; a}}_n}{{\mathrm{with\; a}}_{\mathrm{in}}}.(4)$$

From relations (2) and (4) write

$$\frac{{\mathrm{with\; a}}_n}{{\mathrm{with\; a}}_{\mathrm{in}}}=\frac{S_{H1}-qƒl_{\mathrm{with\; a}K1}b}{qƒl_{\mathrm{with\; a}K1}b},(5)$$

and after transformations recip is m

$$l_{\mathrm{with\; a}K1}=\frac{S_{H1}}{qƒb\left(1+\frac{c_n}{{\mathrm{with\; a}}_{\mathrm{in}}}\right)}.(6)$$

The length of the upper zone slip by analogy with (6) will be

$$l_{\mathrm{with\; a}K2}=\frac{S_{H1}/n}{qƒb\left(1+\frac{c_{\mathrm{in}}}{{\mathrm{with\; a}}_n}\right)},(7)$$

where n is the number that indicates how many times the S_H1more S_H2. For tape-Shoe brakes drilling winches n=4-5.

From (6) and (7) are

For any values of C_nand C_infrom equation (8) we get

$$S_{H1}=qƒb\left(l_{\mathrm{with\; a}K1}+l_{\mathrm{with\; a}K2}\right).(9)$$

From (9) it is seen that in the considered physical model of the tensile force S_H1incoming branches brake master tape 12 is implemented entirely within the zones of elastic sliding. According to (8) and (9) also indicate that the greater the tensile force S_H1the more will slip bands l_W1and l_W2and the more force the contact friction qƒb, the smaller the l_W1and l_W2. The greater the stiffness (C_nmain brake bands 12 in comparison with the stiffness (c_inadditional brake belt 15, the smaller the area l_W1and more area l_W2and Vice versa, in less rigid primary ribbon 12 in comparison with additional tape 15 area l_{W1 more area lW2but always there is dependence (9). For example, if Cn/sin=0,5 from (8) we obtain}

$$qƒb\left(l_{\mathrm{with\; a}K1}+l_{\mathrm{with\; a}K2}\right)=\frac{S_{H1}}{1+0.5}+\frac{S_{H1}}{4\left(1+2\right)}=0.75S_{H1}.(10)$$

Therefore, within the zone of peace l_nboth tapes transmit the tension force S_H1and S_H2corresponding to their rigidity, not moving. In the upper zone of the slide l_W2under the influence of tension force (S_H2additional tape 15 is tensile, and the main strap 12 is weakened due to the contact friction forces. In case of equality of rigidity, the core 12 and an additional 15 tapes_n=C_infrom relations (6) and (7) it follows that l_W1=l_W2that thin strips confirmed experimentally. If you increase the strength of incoming branches (S_H1main brake bands 12 to q$$ƒ$$ bl, elastic slippage in the areas of l_W1and l_W2smoothly go into a total hard slide along the entire length of b, and therefore, when the prior offset of the second kind, the static coefficient of friction of rest is almost equal to the dynamic friction coefficient$$ƒ$$_n=$$ƒ$$_d. This is because at the moment smooth transition brake master tape 12 to the rigid sliding almost no power reserve contact friction.

Hence it is clear that the cause of the pre-bias of the second kind are the tensile strain in the associated core 12 and an additional 15 elastic brake bands associated contact friction, which is his first distinctive feature; the second distinguishing feature is the fact that pre-shift occurs when the movable contact friction, accompanied by elastic displacements, which correspond to the tensile deformations of the material of the tapes 12 and 15, and, thirdly, the transition to the hard slip occurs smoothly and is not accompanied by a noticeable change in the value of the dynamic coefficient of friction.

Band-Shoe brake drawworks with multi-pair nodes friction works with edusim way. The handle 1 is the rotation of the crankshaft 10, in which the driller pulls the core 12 and an additional 15 brake bands, and the circuit brakes. During this stretch (S_H1and S_H2) incoming main branches 12 and 15 additional brake bands overcome the resistance of the interaction surfaces of the friction fastening elements 19 with the side outer surfaces of the additional brake bands 15 and side inner surfaces 14 of the main brake belt 12. Then there is the contact friction between the inner surface 16 of the additional brake bands 15 and the outer surface 13 of the main brake bands 12, aimed at reducing the difference between the forces of tension sections of the ribbons 12 and 15, and, as a consequence, the reduction of spikes of unit loads in pairs of friction surfaces 25 of the friction lining 23 - working surface of the brake pulley 4".

Due to the pliability brake master tape 12 is the interaction of its internal surface 14 with the outer surfaces 24 of the friction lining 23, causing the force of static friction F_n. The greatest efficiency has a pair of friction surfaces 25 of the friction lining 23 - working surface of the brake pulley 4"conducive to stimulating the Oia of the friction force F _Tthe main component of which is the dynamic coefficient of friction ($$ƒ$$_c).

At some point in time deceleration with increasing applied force to the control lever 1, the total force F_Tand F_nwill stop the brake drum 5 drawworks. In a further stage of the brake band brake Shoe drawworks with multipair the friction repeated.

Thus, through the use of composite brake bands, consisting of primary and secondary in the tape-drum brake drawworks, implemented the principle of two incoming branches of the primary and secondary brake bands, as well as additional pairs of friction between the mounting surfaces of the friction elements and ribbons; the surfaces of the tapes; the inner surface of the main belt and outside surfaces of the friction lining, which significantly reduces the uneven distribution of unit loads in friction pairs "cover - pulley and increases the efficiency of the friction nodes brakes due to friction pairs inner surface of the primary tape are non - working surface of the friction lining".

Sources of information

1. A.S. USSR 576455 A1, F15d 49/08 from 15.10.1977, (similar).

2. Patent of Russia 2263832 C2, IPC⁷F16D 49/08 the t 10.11.2005, (prototype).

Band-Shoe brake drawworks with multipair the friction nodes containing the brake pulley on the shaft and additional brake the tape with the attached friction pads, located underneath the main brake the tape and the drive control brake, characterized in that the additional brake band with a friction fastening elements with friction surfaces attached to the brake master tape, and the incident ends attached respectively to the balancer and crank crankshaft necks and during braking due to the tension brake bands and appearance between their surfaces of contact between the slip angles from the incident end the primary and secondary brake bands contact friction, causing decrease of the difference of the forces of tension plots brake bands, which helps reduce uneven distribution of unit loads in friction pairs "cover - pulley", and by rounding the inner surface of the brake master tape outside surfaces of the friction lining, which leads to an additional force of static friction.