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Welding is, of course, good, but it can not be used everywhere. In this case, riveting is used – this is a mechanical connection of parts using special fasteners. These fasteners are called rivets, they are made of different materials, there are different types.
What is a rivet
The mechanical connection of parts using a series of rivets is called a riveting, and the connection itself is called a riveted seam. It is used where it is inconvenient to weld parts or non-weldable materials are connected. Not only metals are riveted, in this way they connect parts in clothes, accessories, etc. But there it is more finishing than a loaded connection. So further we will talk about riveting in construction or home improvement. In principle, instead of riveting, you can use a screw connection, but bolts with nuts are more expensive, and their installation takes more time.
If we talk about installing fences from a profiled sheet, rivets are more reliable, since they can only be removed by reaming the fasteners. When installing screws or self-tapping screws, they can be unscrewed and both metal and hardware can be carried away. In some cases, riveting is more convenient when installing a roof made of corrugated board or metal tiles. On the roof, the installation of screw connections is problematic and time-consuming. And with rivets, and with a good tool, you can do it in an hour or even less.
How are parts connected with rivets? The rivet is installed in the prepared through hole. It has a head that rests against the material and the rod. During the riveting process, the end of the rod is flattened, changing its shape under the influence of force. Therefore, ductile metals are used for these hardware.
Types of rivet seams
If we talk about the method of connecting sheets, then rivet seams are overlapped (one sheet is superimposed on another) and butt. Butt joints can be with one or two overlays. With overlays, they are more reliable, they are used in critical and loaded places.
By the location of the rivets:
- single row;
- double row;
- multi-row.
They can be located opposite each other or in a checkerboard pattern. Seams can be strong, tight (hermetic) or firmly tight. Dense ones are made with the help of elastic gaskets laid between the parts to be joined. Strongly dense are used mainly in boilers. Now they are more often replaced by welding.
Types of rivets
What is a rivet? It is a cylindrical rod of ductile metal (may or may not be hollow) with a shaped head at one end. This head is called a mortgage. During installation, due to the flattening of the metal of the rod from the second side, a second head is formed. It is called closing (closing).
There may be compound rivets (for example, popular pull or screw rivets) that consist of a body and a rod. But the essence of this does not change: the mortgage head rests on the material, and at the other end, due to the plasticity of the metal, a second head is formed. It’s just that it is formed due to the fact that the rod is pulled out and crushes the second part with the expanded part.
Types of rods and embedded heads
Rivets differ in the shape of the head and the core. According to the type of rod, they are:
- with a solid rod (high load capacity, but difficult to install);
- semi-hollow (part of the rod near the mortgage head is solid, part is hollow);
- hollow (the head and the stem have a cylindrical solid hole, they are easily riveted, but they cannot withstand high loads).
Types of rivets by type of rod and embedded head
Rivets have the following types of heads (pictured above):
- Semicircular (high and low). Sometimes also called spherical. The most reliable, create a strong seam.
- Cylindrical and conical (flat). They are used if the connection is in an aggressive environment.
- Hidden and semi-hidden. They are installed when fasteners should not protrude above the surface. The most unreliable connection, used only when necessary.
Each of the types of embedded heads is found with each type of rod. They are selected depending on the planned load. For maximum loads, hardware with a solid rod and a semicircular head is needed. Hollow seams can also be used on not too loaded seams, but they do not provide tightness. If such a characteristic is important, then they put semi-hollow.
Rivet types
Despite the fact that welding has become accessible even to a non-professional, riveting does not lose popularity. After all, not all metals can be welded, and the weld is subject to corrosion. Therefore, new varieties of rivets are constantly appearing, so there is definitely no complete list. Consider the main and more popular.
- Classic or regular. Universal, used for all types of seams. You can distinguish externally – they resemble fungi.
- Semi-tubular (the rod is half hollow). They require less effort during installation, but their strength is also low. Used in connections with a small mechanical load.
Classic and threaded rivets - Mortgages, exhaust, detachable or traction. Composite (two-piece) hardware. The good thing is that during installation they do not need to be held on the second side of the seam. For the installation of fences or the installation of roofing materials, they are used.
- Piston. They are used for connections with low load, they are made mainly from soft metals (aluminum and alloys, copper).
Nut and piston rivets - Threaded (nut). For joining parts with thin walls (up to 0,3 mm). They differ in that the inner part has a cut thread, the outer part has a vertical notch that prevents rotation around its axis. A screw is twisted inside, attracting the free part of the case to the junction. This is how it turns out – due to crushing – a closing head.
These are the main types of rivets that are used in construction, engineering and other areas. Each of the species has its own subspecies, differing in nuances.
Blind rivets
Let’s say a few words separately about exhaust (mortgage) rivets. They are used for fastening profiled sheets and metal tiles. It is with them that you most often have to deal with the arrangement of the site. The blind rivet consists of a tubular body and a solid rod inserted inside. They are called composite because they have two independent parts. Also, this fastener is reinforced – after installation, part of the rod remains inside, which increases the strength of the connection.
The length of the blind rivet body must be greater than the thickness of the parts to be joined. It is inserted into a hole made in advance, after which the riveter grabs the rod, pulls it through the hollow body. At the far end of the rod there is a ball that forms a closing head from the flared edge of the housing. The excess rod is removed with a tool, but some of it remains inside, which makes such a connection strong enough.
As is clear from the description, it is important to choose the right size of the rivet. Too short will not form a normal bead, which will weaken the connection. Too long body will give a lot of backlash, which is also not good. So when choosing this type of fastener, carefully look at the recommended thickness. Ideally, if your connection is in the middle of the range.
Rivets for joining loose and soft materials
To connect soft and plastic materials – plastic, chipboard – the hardware listed above is not suitable. There is another type of similar fastener for them. It is smaller and less durable. But, during installation, less effort is created so as not to destroy the materials.
There are the following types of rivets for joining plastic or soft materials:
- Petal. When installed, the body of the rivet opens into several petals. The large contact area of such a closing head makes it possible to redistribute the load.
Such rivets can be put on plastic, fiberboard and other “non-metals” - Spacer. This is a subspecies of exhaust, but with cuts along the body. When installed, they fold, forming also a kind of petals, but double. In this case, the head of the hardware remains on the surface of the part, without going deep into the material.
There are also plastic rivets. They are usually made for furniture, sometimes for fixing decorative panels. These rivets are more like screw rivets. The lower part is cut into several petals, inside there is a thread through which the rod is screwed. As it twists, the rod pushes the body apart, which is held together by friction.
Metal riveting
The process of riveting metals consists of two stages: preparatory and actual installation of hardware. Preparation – drilling holes, countersinking for countersunk heads if necessary. Please note that countersunk heads can be on one (any) side or on both.
The riveting process itself is as follows:
- insert a rivet;
- pull the connected parts;
- form a closing head with a tool;
- check and clean the connection.
This is how rivets are installed
With a good tool, the work goes quickly. For private use and one-time work, manual riveters are usually used. And even with them, the process itself (without drilling holes) takes a matter of seconds. If we talk about installing a profiled sheet or metal tile, it is recommended to coat each hole made with paint to prevent corrosion. It is these processes – drilling and painting – that take a lot of time.
In general, there are two ways to install rivets: cold and hot. When hot, the junction is preheated to a certain temperature (determined by the metal and the thickness of the parts). In practice, it is used when mounting rivets of large diameter – 12 mm or more.
Rivets are placed in rows. The minimum distance between adjacent ones is 4 diameters, from the edge of the sheet to the center of the hardware – not less than 1,5 rivet diameters. When attaching a profiled sheet, they put it in a recess, not in a wave.
Rivet sizing
Rivets are selected based on the thickness of the joined metals. Important in this case: the parameters of the mortgage head, the diameter of the rod. The diameter of the rod determines the diameter of the drill, which is used to prepare a hole in the parts to be joined. You can roughly determine the diameter of the rivet by doubling the thickness of the parts to be joined. The length of the rod is at least 2 rivet diameters, and the protruding part must be at least 1,25-1,5 of the diameter.
| Rivet diameter | 2,0 mm | 2,3 mm | 2,6 mm | 3,0 mm | 3,5 mm | 4,0 mm | 5,0 mm | 6,0 mm | 7,0 mm | 8,0 mm |
|---|---|---|---|---|---|---|---|---|---|---|
| Precision assembly hole diameter | 2,1 mm | 2,4 mm | 2,7 mm | 3,1 mm | 3,6 mm | 4,1 mm | 5,2 mm | 6,2 mm | 7,2 mm | 8,2 mm |
| Rough assembly hole diameter | 2,3 mm | 2,6 mm | 3,1 mm | 3,5 mm | 4,0 mm | 4,5 mm | 5,7 mm | 6,7 mm | 7,7 mm | 8,7 mm |
In general, the diameter of the rivet shaft can be from 1mm to 36mm, and its length can be from 2mm to 180mm. Moreover, a larger diameter is not equivalent to a greater strength of the connection. Here, both the material from which it is made and its type (hollow or solid) play a role. How to choose? According to the characteristics of the rivets. After all, you choose them for the connection of certain materials of a certain thickness. You also know approximately the load that will be applied to the connection. Therefore, when choosing, pay attention to what the manufacturer recommends.
It must be indicated:
- Recommended connection diameter. You just have to pick up the drill and make a smooth hole without burrs.
- The minimum and maximum thickness of the connected package. It is important that your connection is in the specified range.
- Shear force. This is the load applied perpendicular to the joint that the rivet can withstand without breaking.
- Breaking force. At what load along the rivet will it collapse.
It is the tensile strength and shear strength that determine the strength of the future seam. The higher these values, the greater the load will withstand.
What material should the rivet be from?
Rivets are usually taken from the same material as the parts to be joined – this avoids electrochemical corrosion. Pay attention to the strength characteristics. But, as a rule, when connecting aluminum parts, the strength of aluminum hardware is sufficient.
In general, rivets are made from the following metals:
- steel:
- ordinary – grades St2, St3, St10;
- corrosion-resistant Х18Н9Т;
- galvanized;
You can get lost)) - alloyed (stainless) – 9G2, 304, 316.
- copper MT and M3;
- aluminum alloys (more often AD1, D18);
- aluminum-magnesium (AlMg2,5; AlMg5; AlMg3),
- brass (L63).
When connecting copper parts, the installation of brass and copper is acceptable. Aluminum is bonded with aluminum alloys. Steel sheets – with the corresponding grades of steel rivets. There are also mixed hardware – from two different metals (not chemically conflicting). The most common are aluminium-steel.
To install facade elements, slopes, ebbs, metal tiles and profiled sheets, blind rivets made of galvanized painted steel are usually used. Coloring – in tone with details.