EA007687B1 - Six-membered mechanism of variable structure - Google Patents

Abstract

A six-membered mechanism of variable structure is used in mechanisms of drilling and breaking machines and can be used in mining industry, construction and machine engineering. The technical inventive task is to expand kinematic abilities and improve mechanism efficiency.A six-membered mechanism of variable structure comprises a housing 1, a double crank 2, an upper 3 and lower connecting rods 5, a rocking arm 4 with impact mass 7 and a slider 6. The crank shaft 2 rotates around an stationary axis Oenters into a rotating pair Owith the upper connecting rod 3 and into a rotating pair Owith the lower connecting rod 5. The upper connecting rod 3 enters into the rotating pair Owith the rocking arm 4, which, in its turn, enters into the rotating pair Owith the slider 6 traveling along a stationary guide 1. The rocking arm support is movable on rectangular guides with the slider 6 mounted thereon. The mechanism member length are selected adapted to be put in one line the slider being in the extreme position from the crank support side. The base length can be regulated in a non-stop regime.

Description

The invention relates to the mechanisms of drilling and blasting machines and can be used in the mining industry, in construction and engineering.

Known lever mechanism [1], which contains a rack, a control device, an elastic element and a crank, a connecting rod, a yoke and a slider pivotally interconnected. On the slider there is a clamp fixed rigidly connected with the rocker. The elastic element is installed between the stand and the slide, and the control device is made in the form of power cylinders.

During the rotation of the crank relative to the rack, the movement through the connecting rod is transmitted to the rocker arm, which makes a swinging movement about the axis fixed to the slider and in a state of rest. When the control device is turned on, its stem moves the slider a certain distance, squeezing the elastic element. This changes the angle of swing of the rocker. In the upper position of the crank, the connecting rod and the rocker line up in one line. In this case, the retainer roller fixes the rocker and with further rotation of the crank, the slider makes a reciprocating movement. When the control device is turned on, its rod acts on the lever of the rocker arm, which is released from fixation, and the slider under the action of the elastic element moves up and stops. The rocker with the further rotation of the crank makes a swinging movement.

The disadvantage of the lever mechanism is the low rotational speed of the crank, which is caused by the inconsistency of its rotation and return of the slide, with the help of an elastic element to its original position. Limited rotational speed of the crank reduces the energy parameters of the mechanism. In addition, the elastic element introduced into the structure has low reliability and inertia.

The excitation of high-power energy, formed by reciprocating movement, leads to significant vibrations, which require additional devices to extinguish them.

The prototype of the selected mechanical hammer [2], which includes a housing with a drive, crank-lever platoon, tool, pusher and a spring-loaded movable support, which is pivotally connected to the end of the rocker arm.

The crank-and-lever cocking device is a four-hinged mechanism consisting of a crank, a connecting rod and a rocker arm with a shock weight. The support of the rocker is spring-loaded relative to the body by means of a spring. With the help of the pusher, the rocker support is kinematically connected with the tool profile. The tool is also mounted on the body and is spring-loaded relative to the body using an elastic element.

This mechanism with a constant rotation of the crank in the idle mode can work as a hinged-lever mechanism, and in the operating mode - as a crank-slider mechanism. The transition from one structure to another is carried out by moving the support of the rocker with the inclusion device. In this case, the rolling angle of the rocker arm changes and at the upper position of the crank the rocker arm is captured by the support. By the end of the transition mode, the pivot-lever mechanism turns into a slider crank and goes into operation mode.

The disadvantage of this device is low reliability due to the presence of a spring-loaded movable support mechanism.

The technical problem of the invention is the expansion of the kinematic capabilities and efficiency of the mechanism.

The task is achieved by the fact that a six-link mechanism of variable structure, comprising a housing, a double-arm crank, two connecting rods, a rocker arm, and a slider, which, as an output link of a crank-slider mechanism, is connected by an articulated output link of the crank mechanism, and the lengths of the links of the six-piece mechanism are configured alignment in one line in the extreme position of the slide on the side of the crank support. The presence in the proposed mechanism of the slider with the support of the rocker arm O ₄ installed on it allows the six-part mechanism to combine simultaneously the crank-beam and crank-slider mechanisms of variable structure, which eliminates additional dynamic loads in the supports to a minimum and transferring reactive forces to the crank. The double-arm crank is mounted on a stand and is kinematically connected with the beam through the upper connecting rod, and with the slider through the lower connecting rod. The six-link mechanism is illustrated by drawings, where in FIG. 1 schematically shows a general view;

in fig. 2 - the same at the moment when the slider is in the extreme right position;

in fig. 3 - the same with the "special position".

The six-element mechanism of variable structure consists of body 1, double-shouldered crank 2, upper 3 and lower 5 rods, rocker arms 4 with impact weight 7 and slide 6. Double-arm crank 2 rotating around a fixed axis O1 enters the rotary pair O2 with upper rod 3, and into the rotational pair of O ₅ with the lower connecting rod 5. The upper connecting rod 3 enters the rotational pair of O ₃ with the rocker 4, which in turn enters the rotational pair of O ₄ with the slider 6. The lower connecting rod 5 enters the rotational pair of O ₄ with the slider 6 sliding along a fixed guide 1. The hinges O ₁ and O ₄ serve as a support for crank 2 and connecting rod 5, respectively. The support of the rocker arm is made movable on straight guides, with a slider 6 installed in them. The length of the base 1 is adjusted during operation.

- 1 007687

The mechanism works as follows.

When the double-shouldered crank 2 rotates relative to the stand 1, the movement through the upper connecting rod 3 is transmitted to the rocker arm 4, which oscillates about the axis fixed to the slider 6. This changes the angle of swing of the rocker arm 4. The other end of the double-shoulder crank 2 acts on the slider 6 and brings it into reciprocating motion. Thereby, two motion modes are simultaneously performed. The first is the swinging movement of the rocker arm 4 with a shock mass of 7, and the second is the reciprocating movement of the slide 6.

When the crank 2 rotates in the counterclockwise direction, the rocker arm 4 with impact mass 7 rotates in the same direction, i.e. the direction of rotation of the crank 2 and the rocker arm 4 with a shock mass of 7 are the same. When the crank 2 reaches the leftmost position, the length of the base of the mechanism is the maximum value and the slider occupies the extreme right position (Fig. 2). In the case when the crank 2 and the upper connecting rod 3 are located on the same line, the movement of the rocker arm 4 with the impact mass 7 instantaneously stops. With further rotation of the crank 2, the rocker 4 with the shock mass 7 continues to move in the opposite direction, this changes the swing angle of the rocker arm 4 with the shock mass 7 and the lower connecting rod 5 moves the rocker arm 6 to the left. The minimum value of the length of the base of the mechanism corresponds to the special position when all links are lined up in one line (Fig. 3). With further rotation of the crank 2, the rocker 4 with a shock mass 7 swings under the influence of the connecting rod 3. The support of the rocker arm 6 returns to its original position and the mechanism goes into idle mode. As the reduced positions of the links of the mechanism show, the full cycle of operation of the percussion mechanism consists of two periods: reverse and working stroke of the rocker arm 4. Crank 2 is in a special position of the mechanism, connecting rods 3 and 5 and the rocker arm 4 line up in one line. It should be noted that the base length is self-regulating.

Thus, the proposed design eliminates the additional conversion of the input energy, which allows to increase the efficiency of the mechanism, and setting the shock mass on the rocker allows you to increase the impact energy by increasing the speed and mass of the shock mass.

Compared with the known devices, the use of the proposed mechanism provides a significant economic effect, since the input power to the treated medium increases, which is caused by increased energy and frequency of strikes of the striker.

The increase of the power input to the processed medium is carried out with an increased efficiency of the proposed mechanism, which increases the efficiency with a significant decrease in the energy loss of the system. The application of the proposed mechanism improves the reliability and durability of the executive bodies of the percussion machines, since the transition from idle to working mode is performed without additional devices.

Claims (1)

CLAIM A six-member mechanism of variable structure comprising a housing, a two-arm crank, two connecting rods, a rocker and a slider, characterized in that the output link of the crank-rocker mechanism is pivotally mounted to the output link of the crank-slide mechanism, and the lengths of the mechanism links are arranged to be aligned in a single line the extreme position of the slider on the side of the crank support.