There are no minor details in the construction. Any elements used in the construction of buildings and structures must be of good quality and have a long service life. This also applies to various kinds of fasteners, including, of course, and their most popular variety today - self-tapping screws. How to make such a building consumable - we'll talk about this later in the article.
What are they made of?
Self-tapping screws in construction are used in the assembly of wall frames of houses, rafter systems, floor and ceiling packing, cladding of walling. That is, the load on such fasteners during the operation of the house is significant. Therefore, the material for the production of such elements should be used very durable and also sufficiently plastic.
At modern enterprises, self-tapping screws are, of course, made of steel. In this case, the production of such elements is usually chemically-thermally processed material of this type ST 10 KP or ST 08 KP. Such steel has a fairly high rate of surface hardness and ductility. Its only drawback is an increased tendency to aging.
From steel ST 10 KP or ST 08 KP, a wire is preliminarily made, the diameter of which corresponds to the diameter of the leg of future screws. Further, such material is wound in coils and sent to factories specializing in the manufacture of building fasteners.
The first stage is the manufacture of blanks
So how do self-tapping screws in factories? At enterprises engaged in the production of such consumables, steel wire is fed to special cold heading machines. On such equipment, it is pre-straightened. Then, directly on the machine, the wire blanks are made for self-tapping screws. I.e:
The slot on the hats of self-tapping screws on cold heading machines can be printed both for cross-head and conventional screwdrivers.
Thread cutting
After manufacturing the blanks for self-tapping screws, the plants undergo the most rigorous quality control. Specialists selectively measure the length of the fasteners and their diameter. A visual inspection of the blanks is also carried out to identify mechanical damage on their surface. Some batches of discs, therefore, after passing the cold heading machine can be discarded.
The quality control of the workpiece is then fed to a threading machine. From the conveyor line, discs are poured into a special auger, which, turning a large number of blanks at once, exposes them with the hat up. In this position, the blanks are subsequently fed into a special device for threading. In this assembly of the machine, each workpiece is pulled by a rolling movement between special flat dies. As a result, a thread is formed on its leg, as well as a self-cutting tip.
How to make self-tapping screws: hardening
After the threading machine, the fasteners in the factory take on a form already familiar to everyone. Having passed flat dies, almost finished self-tapping screws are poured into a special hopper and transported to a thermal furnace. Previously, such products undergo another quality control at the enterprise.
Firing in thermal furnaces of fasteners is rather slow. In this case, heat treatment is usually performed at a temperature of more than 930 ° C. After the furnace, the screws are also fed through the line to special containers with coolant. Thus, the hardening of the fasteners occurs.
Dyeing
After hardening, the screws are fed into special equipment for applying a protective coating against corrosion. Depending on the purpose of the fasteners (for wood, metal, etc.), they can be processed at this stage by:
For example, self-tapping screws designed for metal work are usually yellow.
Final stage
The technology described above is the answer to the question of how to make screws on wood, metal, stone, etc. In any case, after applying a protective coating, the finished screws are fed to the packaging line. Previously they go through the final quality control procedure. After such a check, only the most durable fasteners that fully comply with the standards and norms remain.
In large enterprises, the packaging process is usually also fully automated. Special equipment in such factories makes cardboard boxes from box blanks, into each of which a certain amount of self-tapping screws is poured by weight. Further, the boxes filled with fasteners are assembled into blocks of several pieces and fed to the finished product dispatch department.
Automatic lines
So, how do self-tapping screws, we found out. In small enterprises, only cold heading machines and thread-cutting machines are usually used for the manufacture of such elements. At the same time, such workshops are engaged in the production of the simplest wood screws. At large enterprises, automated, very expensive lines are installed for the manufacture of such fasteners.
From one type of equipment to another, self-tapping screws at such plants are fed along conveyor lines. At the same time, they can be transported in elevators-bunkers between the tiers of the production workshop.
In addition to cold heading and thread-cutting, the structural elements of automatic lines for the production of self-tapping screws in Russia can be:
thermal furnaces;
tanks for hardening;
painting lines;
Packaging equipment.
What is a cold heading machine?
Such equipment belongs to the group of machines:
stationary medium-sized;
universal high-speed;
automated two-stroke;
continuous action.
Used machines of this kind can be used for the production of not only screws, but also almost any other type of fasteners - bolts, screws, etc. In this case, it all depends on the settings of such equipment.
Mounted cold heading machines based on a rigid welded frame. The wire feed to the main node in them is made from the bay with a ratchet device step by step. The length of the workpiece in machines of this type is regulated by rearranging the stop. Landing strikes in equipment are performed by a punch. The first blow in this case drives the rod to the stop, and the second one forms the head.
How self-tapping screws are made in enterprises is thus understandable. The production technology of such fasteners, in principle, is not too complicated. Moreover, the cold heading machines themselves produce blanks very quickly. Depending on the performance and power indicators, one such unit per minute can produce up to 100-300 self-tapping screws.
Thread rolling machine for the production of self-tapping screws
In such equipment, discs are supplied between the dies individually. At the same time, as already mentioned, they are strictly oriented towards such work items. Flat dies in the machine move towards parallel to each other and perpendicular to the axis of the self-tapping screw. Such working elements of machines are made according to the necessary parameters of the thread. At the same time, domestic manufacturers of self-tapping screws take metric sizes as the basis, foreign - inch.