What is Metal Profile?

What are metal profiles?

Metal profiles refer to geometrically shaped metal objects with a certain cross-sectional shape and size after metal plastic processing. There are two common metal profiles on the market, steel profile, and aluminum profile, they are respectively obtained by roll forming, drawn, pressed(steel), or extrusion(aluminum) process manufacturing process.

The metal profile has a certain appearance size, a certain cross-section shape, and certain mechanical and physical properties. Metal profiles can be used alone or further processed into other manufactured products, often used in building structures and manufacturing installations. Mechanical engineers can select the specific shape, material, heat treatment state, mechanical properties, and other parameters of the profile according to the design requirements, and then divide the profile according to the specific size and shape requirements, and then further process or heat treatment to meet the design accuracy requirements.

Steel profiles are mainly used in the cost-efficient and reliable envelopes of the construction sector, but are also useful for many other types of applications. Aluminum profiles are durable for industrial use for building machines, solid structures, and automation, or for civil uses such as building doors, windows, and lamps.

Types of metal profiles: Typical metal profiles and structural shapes include metals and alloys in the form of bars, rods, channels, angles, pipes, tubes, tees, beams, plates, foils, and other standard shapes.

Production characteristics of metal profiles

Profile production has the following characteristics:

• There are many varieties and specifications. It has reached more than 10,000 types, and in production, except for a few special-purpose rolling mills to produce special products, most profile rolling mills are producing multiple varieties and specifications.
• The cross-sectional shape varies greatly. Among profile products, except for square, round, and flat steel section shapes that are simple and have little difference, most complex section profiles (such as I-beam, H-beam, Z-beam, channel steel, rail, etc.) not only have complex cross-section shapes, Moreover, they are quite different from each other. The pass design and rolling production of these products have their own particularities; the complexity of the cross-sectional shape makes the deformation of each part of the metal, the temperature distribution of the cross-section, and the wear of the rolls different during the rolling process. Therefore, it is difficult to accurately calculate and control the size of the rolled piece, and the adjustment of the rolling mill and the installation of the guide device are also complicated; in addition, the single variety or specification of complex cross-section profiles is usually small in batches. The above-mentioned factors make the development of continuous rolling technology for profiles with complex sections difficult.
• There are many rolling mill structures and rolling mill layouts. In terms of structure, there are two-roll mills, three-roll mills, four-roll universal mills, multi-roll mills, Y mills, 45° mills, and cantilever mills. There are horizontal rolling mills, in-line rolling mills, checkerboard rolling mills, semi-continuous rolling mills, and continuous rolling mills in the form of rolling mill layouts.

Five types of metal profiles

The common classification methods of profiles mainly include the following five types:

Production method

Profiles can be divided into hot-rolled profiles, cold-formed profiles, cold-rolled profiles, cold-drawn profiles, extruded profiles, forged profiles, hot-bent profiles, welded profiles, and special rolled profiles according to the production method.

According to the characteristics of the section

Profiles can be divided into simple section profiles and complex section profiles according to their cross-sectional shapes.

• The cross-section of simple cross-section profiles is symmetrical, and the shape is relatively uniform and simple, such as round steel, wire rod, square steel, and steel.
• Profiles with complex sections are also called profiles with special-shaped sections, which are characterized by obvious convex and concave branches in the cross-section. Therefore, it can be further divided into flange profiles, multi-step profiles, wide and thin profiles, local special processing profiles, irregular curve profiles, composite profiles, periodic section profiles, and wire materials, etc.

Application

The profiles are classified according to the departments used: profiles for railways (steel rails, fishplates, rails for turnouts, wheels, tires), profiles for automobiles (rims, tire retaining rings, and lock rings), profiles for shipbuilding (L-shaped steel, spherical flat steel, Z-shaped steel, marine window frame steel), structural and architectural profiles (H-shaped steel, I-shaped steel, channel steel, angle steel, plate/sheet metal, crane rails, window and door frame materials, steel sheet piles, etc.), mine steel (U-shaped steel, channel side steel, mining I-beam, scraper steel, etc.), special profiles for machinery manufacturing, etc.

Section size

Profiles can be divided into large, medium, and small profiles according to their cross-sectional size, and they are often classified according to their suitability for rolling on large, medium, and small rolling mills. The distinction between large, medium and small is actually not strict. There is also a method of distinguishing by single weight (kg/m). It is generally believed that those with a unit weight of less than 5 kg/m are small profiles, those with a unit weight of 5 to 20 kg/m are medium profiles, and those with a unit weight of more than 20 kg/m are large profiles.

How are metal profiles(steel) made?

Blooming

The concept of blanking has two meanings: primary rolling blooming and secondary blooming. Blooming is to roll a few heavy steel billets produced by steelmaking into the large billets required by the steel rolling mill through the blooming mill. Secondary billeting is to further roll the first rolling billet of the cross-section into a small billet and supply it to the finished product rolling mill.

Heating and Rolling

The purpose of heating is to reduce the deformation resistance of the metal, improve the plasticity of the metal, and improve its structural properties.
Profile rolling is divided into rough rolling, intermediate rolling, and finishing rolling.

The task of rough rolling is to roll the billet into a suitable prototype intermediate billet. In the rough rolling stage, the temperature of the rolled piece is high, and the uneven deformation should be placed in the rough rolling past the rolling stage as much as possible.
The task of intermediate rolling is to make the rolled piece extend rapidly and approach the finished product size.
Finish rolling is to ensure the dimensional accuracy of the product, and that the elongation is small.

The elongation coefficients of the finished hole and the pre-finished hole are generally 1.1~1.2 and 1.2~1.3 respectively.

Requirements for the rolling process

A billet of one specification is rolled into intermediate billets of various sizes in the rough rolling stage. Rough rolling of section steel is generally carried out in a two-roll pass.
If continuous casting slabs are used for all section steel slabs, from the perspective of steelmaking and continuous casting production organization, the smaller the size specifications of the continuous casting slabs, the better, and it is best to only require one specification.
However, the more sizes and specifications of finished section steel products, the stronger the enterprise’s ability to open up the market. This requires rough rolling to have the ability to cut a billet into billets of various specifications.

Three notes

• Rough rolling can not only carry out waist-expanding and edge-expanding rolling for profiled billets but also carry out waist-shrinking and edge-reducing rolling. Its more typical example is rolling an H-beam with a slab.
• For profiled materials, use as many passes as possible and multi-roll passes in the middle rolling and finishing rolling stages. Since the multi-roll pass and the universal pass are conducive to rolling thin and high sides, and it is easy to individually adjust the reduction of each part on the section of the rolled piece, it can effectively reduce the uneven wear of the roll and improve the dimensional accuracy.
• For continuous rolling of section steel, loopers cannot be used due to the large section coefficient of the rolled piece. The tension control between the frame is generally carried out by using the current memory method or the torque memory method of driving the main motor.

For most section steels, good low-temperature toughness and good weldability are generally required in use. In order to ensure these properties, low carbon equivalent is required in materials. For these steels, low-temperature heating and low-temperature rolling can refine the grains and improve the mechanical properties of the material. Water cooling after finishing rolling also has obvious benefits for improving material properties and reducing cooling time on the cooling bed.

Finishing

There are two processes for post-rolling finishing of profiles, one is the traditional hot sawing to length, length straightening process, and the other is the newer long-length cooling, long length straightening, and cold sawing process.
Profile finishing, the more prominent is straightening. The straightening of profiles is more difficult than that of plates and pipes. The reasons are:

• Firstly, during the cooling process, the bending caused by asymmetrical sections and uneven temperature is large;
• Secondly, the section coefficient of profiles is large, and the straightening force required is large.

Due to the relatively large section of the rolled piece, the roll distance of the straightening machine must also be large, and the blind area of straightening is large. Under some conditions, it has a great impact on the use of steel. For example, the straightening blind area of heavy rails is significantly reduced. The overall straightness of the heavy rail. To reduce the straightening blind area, the measure on the equipment is to use a variable intercept straightening machine, and the measure on the process is to straighten with a long ruler.

Application of metal profiles(steel)

Metal profile sheets due to their versatility in mechanical and design properties can be used as roof and roof cladding, as external walls and wall cladding, and also as floors. They are used in industry and the residential sector, and the two sectors can be used in both new construction and rehabilitation. Some of the applications where metal profile sheets are used are:

• industrial buildings,
• commercial buildings,
• public buildings,
• sports buildings,
• educational buildings,
• offices and administration buildings,
• multi-story buildings
• power plants,
• residential house,
• high-design demand buildings,
• etc.

More bending methods for metal profiles

Reference Reading: Best Beginner’s Guide to Metal Profile Bending