Today, the SDS chuck is indispensable for professional or household construction equipment. This technology is used in 90% of perforators worldwide. And it is popular not only because it speeds up and simplifies the process of handling the tool. And also because it allows you to protect the cartridge from the harmful effects of an impulse impact.
HISTORY OF CREATION OF THE SDS SYSTEM.
In 1932, the Bosch company developed the world's first perforator with a hammering mode. Impulse dabbing mode now worked in conjunction with torque. And everyone liked this invention - the perforator became very popular.
However, impact drilling in the process of work had a negative impact on the cartridge, which was already quite fragile, as it consisted of many separate parts. In order to exclude the cartridge from the shock chain in 1975-1977, the Bosch company developed a new mechanism called "Steck - Dreh - Sitzt", which in German means: "insert", "turn", "fixed". In English-speaking countries, SDS received the name "Special Direct System", which in Russian meant "special direct system". Subsequently, five types of SDS system cartridges appeared, for which drills with landing rods of different diameters are manufactured (SDS, SDS-plus, SDS-top, SDS-max, SDS-quick).
The SDS-Plus chuck quickly fixes the bit with the help of locking balls
SDS CARTRIDGE DEVICE.
The drills themselves can easily tell about the principle of operation of the SDS cartridge, or rather, their structural structure. Looking at the drill, you can understand the simplicity and ingenuity of this invention.
On the landing surface you can see four grooves - two of which are closed at the end, and two are open. The open grooves act as guides for inserting drills into the chuck, and the closed grooves act as stoppers, for fixing inside the chuck with locking balls. The fixed drill is slightly shifted along the axis and so that it can "walk" easily, it is lubricated with a small amount of consistent grease. It is the relatively free movement of the drill inside the cartridge that allows you to separate the cartridge itself from the strong impact produced by the drill bit, crown or chisel. This design has a small radial runout at idle, which does not affect the accuracy of drilling, because the drill bit self-centers during operation.
Construction of the SDS-plus drill shank
The SDS-plus chuck is specially designed for a drill tool with a uniform shank diameter of 10 mm, with a total maximum length of 110 to 1000 mm, and a working diameter of 4 to 26 mm (the shank is inserted approximately 40 mm; the most used drill diameters: 6.8 , 10.12 mm; the contact area of the wedges is 75 mm?).
This is the most common type of cartridge, as it is mostly used on light and medium-class equipment, in wide household use. According to statistics, by 1998, more than 10 million SDS+ class drills were sold.
PRINCIPLE OF THE SDS-PLUS MECHANISM SCHEMATICLY:
The principle of action of the SDS-Plus mechanism
1. two closed, oval grooves of semicircular section;
2. locking balls for fixation;
3. two open trapezoidal sections;
4. internal guides of the SDS-max cartridge;
5. the depth to which the rod is inserted reaches approximately 40 mm.