Connection articulated by hand

The need to mount the parts so that they could move during the operation of the mechanism led to the invention of simple and complex articulated joints. In this article we will talk about this in more detail.

What is a hinged connection?

The device by which two parts are connected together, while retaining mobility around a common axis, is called a hinged connection. It consists of a trunnion and a holder. The device has received the widest development and modification. It is used in various fields of industry and national economy.

In the cylindrical hinge, the trunnion usually has the form of a rod. It is pressed into the holes of another part, called a cage. The simplest example of a hinged connection is the door hinge. Having looked at them carefully, it is easy to understand the principle of the device's operation. Both parts of the hinges are equipped with hollow cylinders, which are connection clips. A pin (usually densely pressed into one of them) is a finger.

The parts thus connected move around a common axis. Cylindrical hinge is found in simple and complex mechanisms. He is present even in the usual clerical stapler.

Complex articulated joints

A more complex hinged joint consists of a pin, pressed into the inner cage of a plain bearing or rolling bearing, rotating in it. No electric motor can be assembled without the use of this unit. The rotor is suspended in the stator by means of a cylindrical hinge using sliding or rolling bearings. The wheels of railway cars are fixed to the trolleys by means of a hinge with a casing of the axle, the finger is the axis of the wheel sliding in it by means of a roller bearing.

Ball joint

There are other types of hinged joints that can provide more degrees of freedom of rotating structures. The joining of parts at which they move around a common center is called a ball joint. The trunnion in it is made in the form of a sphere.

Unlike cylindrical, the ball joint pin has all degrees of freedom. Being limited only in its place of position, it provides the details, articulated with its help, the possibility of moving in different directions.

A ball joint is called a spherical kinematic pair. The housing, which accommodates a ball-shaped pin, is usually made of cast iron. The parts assembled in such a unit are capable of taking positions at different angles to each other. To reduce the friction of the surfaces in the pivot joint, special liners are protected from contact with the body filled with lubricant. The dust cover closes the hinge from dirt and prevents leakage of grease.

All existing mechanisms are initially seen in the phenomena of nature. As well as the ball joint, very reminiscent of the hip joints and spinal vertebrae of the human body.

Evolution of a cylindrical hinge

A knot of two cylindrical hinges with perpendicularly placed pins is used in the cardan gear. It was named after Jerolamo Cardano, who described it in the 16th century.

The cylindrical kinematic pair was invented by the English physicist Robert Hooke, used to transfer the rotational moment. Uninterrupted operation of the unit ensures that the alignment condition of the drive shaft parts is compulsory. Otherwise, under certain loads, the hinge connection starts to collapse. In case of misalignment of the movement of parts, it is advisable to use a cardan with two crossings. This method is used in the case when the rotational moment is transmitted along axes that are at an angle. Adding a cross increases the number of degrees of freedom, relieves stress on trunnions and forks, and prevents their destruction.

Using

Using the Hook Hook in the automotive industry made it possible to transfer rotational motion from the gearbox to the wheels even if there are significant joint angles. This knot subsequently formed the basis of a cam-disc hinge consisting of a disk of forks and cams, which are mainly used in trucks.

SHRUS

The peculiar mutant obtained by crossing the ball joint with the Hooke cardan represents an entirely new kind of connection of the elements. It is a deformed ball bearing, where the inner casing takes the form of a sphere with slots, and the outer ring - spheres with grooves on the inner surface. Both rings are attached to the drive shaft using a splined connection . The balls placed between them hold the separator.

The hinge of equal angular speeds at large angles of rotation undergoes great loads. "Inverted wheels" at nominal speeds are fraught with damage to the unit.

SHRUSS are subject to obligatory hermetic sealing. Their place of operation contributes to the ingress of dust and moisture into the hinge, which quickly disables it. Abrasives and corrosion destroy the grooves, balls, kill the separator. Modern cars use a very reliable hinged joint, sealed in a casing, which contributes to the full utilization of its resource.

The articulation requires periodic inspections of the rubber cover. The preservation of its integrity protects the unit from contamination. If a violation of its tightness is detected, it is desirable to replace the entire hinge.

Non-traditional hinges

The original application found a cylindrical joint in the manufacture of furniture products. Doors, blinds, decorative partitions, assembled from racks, became available with the advent of woodworking mills on the market. The presence of a small machine will help you easily make a swivel connection with your own hands.

The passage with the edge rebate cutter forms a rough groove on one of the narrow faces of the wooden strip. Then it passes through a groove shaped cutter to obtain a shaped groove.

On the other hand, a spike is formed. It is obtained by two finishing passes. It will help to make a cylindrical articulated joint cutter edge curly. After the edges are rounded, the rake takes a finished look.

Alternately fixing on the milling machine a suitable milling cutter and passing a wooden billet along it, the hinge joints are made. By assembling the spike-in-groove strips, a flexible sheet material is obtained, which, depending on the width of the parts and the density of the joints, can be folded into a tube up to 15 cm in diameter.

Pipe joints in their design have much in common with SHRUS: two spherical cages, between which in the grooves are the balls held by the separator. The use of fluoroplastic rings provides a radial seal of the joint. The inner casing is connected to one end of the pipeline, the outer casing to the other.

Thus, both pipelines are able to freely rotate in all directions relative to each other. The mutual fixation of the clips is provided by the balls that are between them.

Pouring-filling elements of pipelines operate under conditions of frequent changes in the direction of supply of the transported substance. To accelerate the redeployment on such highways, a swivel joint of the pipes is used. It can be used in the oil-producing, petrochemical, food or gas industries.

Summarize

In today's world, wherever you look, everywhere hinges: dolls and headphones, wheels and tower cranes, children's driven cars and swing-hats are all made using them. Sometimes they are mutated beyond recognition.