Riveting joints: advantages and disadvantages
Riveting joints are made of special parts. Such a fixed bond is difficult to separate. The rivets themselves are made of plastic material.
Riveting joints consist of three elements:
- two parts of the connected parts;
The last element is placed in special holes, which are located on the edges of the parts to be joined.The rivet holds the parts in the desired position. In this case, the fastening element has the following structure:
- Mortar head - serves to form the future product;
- closing head - formed during the joining of two elements.
A large number of rivets are used to fasten large parts. In this case, the finished joint will be called a riveted seam.
Before the appearance of high-quality weldingrivet connection of parts was widespread. Currently, it is used in some areas of technology. Riveting joints of parts are used in the construction of aircraft, ships, submarines, as well as for various high-precision instruments. In addition, rivets are used for joining building elements, such as an I-beam, channel, corner.They help to withstand variable vibrationalload. Riveting joints are used to combine different types of material. For example, to fasten products from a cast iron alloy with an aluminum sheet.
Riveting joints. Advantages and disadvantages of the bonding method
Among the positive sides are:
- simple technological execution;
- the ability to combine dissimilar metals;
- high reliability of connection;
- counteracts vibration and shock loads.
However, like every compound, there are some disadvantages, among which are the following:
- to create riveted fastening, it is necessary to spend a large amount of metal;
- requires significant labor costs;
- high price;
- riveted joints can be destroyed due to the incorrect diameter of the holes that are on the edges of the products;
- During operation, the tightness of the connection is reduced.
There are many kinds of riveted joints, since each of them is applied in a certain industry.
This type of connection is divided according to this principle:
1. Functional purpose. Among the compounds there are three main types: strong are used to hold large loads; Dense, which ensure tightness; combined - perform both functions.
2. Technological design of the seam. The joint can be overlapped and butted.The last view is performed using one or more overlays.
3. Number of slices. This indicator shows the number of slices passing through one rivet under the action of the load. According to this principle, riveted joints are one-and multi-cut. Their number is not limited.
4. The number of riveted rows. They can be one, two, three, etc. The quantity is not limited.
As discussed earlier, riveted jointsare used in various industries. Therefore, there are different types of rivets. In addition to the above indicators, these types are classified according to the shape of the mortise heads:
In its form are the following types:
- hollow (have a through hole);
- half-hollow - the rod is divided into two parts: one is solid, and the other is hollow.
The basic information about fasteners and components is contained in the regulatory documentation.Characterizing the riveted joints of GOST 10303-68 includes the main rivet sizes. Here its diameter, length of the body and the rod, and also the type of the head are registered.
Material of manufacture
The main materials for manufacturingriveted joints are low-carbon steels, non-ferrous metals, and also some alloys. Despite this, each material has strict requirements:
- To facilitate the installation of the product, the material must be ductile.
- Materials should have the same temperatureexponent. If this requirement is not met, additional stress will occur with temperature changes. In the end, riveted joints will collapse.
- Materials must be homogeneous. This is done so that the galvanic current does not destroy the connections. For example, for fastening steel parts, steel rivets are used, copper elements - copper, etc.
The permissible ones were determined as a result of numerous tests and experiments. In addition, they were thoroughly studied by specialists.There are several types of loads: shear stress, tension and crushing. For each type of metal, these indicators differ from each other.
When using two elements of low-carbon steel, the permissible tensile load should not exceed 150 MPa, and the shear stress should not be more than 100 MPa.
It should be noted that these indicators were developed not only for the connecting elements, but also for rivets.For them, there are their own permissible loads. For example, for products made of carbon steel, the shear stress should not exceed 100 MPa. For crushing, it is not more than 300 MPa.
The permissible loads for the elements depend on the method of making holes in the products.If there is a high voltage, the holes must be made by drilling.
In the case of temporary exposure to the product, the permissible loads are reduced by 20%. In some cases, for example with a cold rivet, this figure is reduced by 30%.
Recommendations for the production of riveted joints
These rules for fabricating the connection weredeveloped by highly qualified specialists. They were identified as a result of many years of testing in the laboratory, as well as during the operation of the connection. So, among them there are:
1. The connecting parts and rivets must be made of a strong, uniform material.
2. Rivets should provide a small amount of attenuation between the parts. For this, as a rule, I use the chess method of fixing.
3. The appearance of bending of the main structural elements should be avoided. To do this, the rivets are positioned along the axis that passes through the center of the connected elements.
4. On one riveted joint, elements that have different diameters can not be used.
5. To avoid turning the parts to be joined, the number of rivets must be at least two.
6. The number of elements on one side must be no more than three. With increasing this index, the strength of the product will decrease.
7. With a butt joint, more rivets should be used than the overlapped joint.
8. It is necessary to ensure tightness. For this purpose, special glue or paint is applied at the rivet points, which are obtained with the help of flame spraying.
9. After fixing the parts, a check is made.
10. The number of rivets depends on the developed riveted joint design.
This connection is not very common nowadays. It is almost completely replaced by welding.However, it is used in the production of aircraft,ships, as well as some devices. The main advantages are high strength of the finished joint and easy installation. However, to use it, it is necessary to spend a significant amount of metal. Therefore, this type of connection is expensive and time consuming.
Riveting joints exist in large numbers.The main types and sizes of rivets are indicated innormative documentation. The type of element depends on the industry used. Installation of them requires precise execution. The slightest deviation in the diameter of the hole can lead to the destruction of the entire product.When they are manufactured, it is necessary to adhere to certain rules that were compiled by specialists on the basis of long-term calculations and experiments.
So, we have considered the peculiarities of this kind of connections.