DESCRIPTION GUN EXTRUDER Technical Field This invention relates to a gun extruder. In prior art gun extruders are known. The present invention makes specific reference to gun extruders for dope cartridges (like silicon). Background &H Today, known gun extruders have the drawback of being large, complex, expensive and little functional. The aim of the present invention is to make a compact extruder which is functional and of maximum reliance. The present invention, according to the characteristics of the included claims, solves the problem by means of an extruder for dope and other cartridge materials by means of base thrust, of the type having a power-operated gun form to which tube extremity is fixed the cartridge or cartridge carrier, and which has a trigger command which exits or re-enters a piston pushed by said tube, that pushes the base of said cartridge causing the material contained in it to exit from an end spout for application, characterized in that said pushing piston, develops telescopically forwards by means of: - a first bush threaded internally, axially static, and rotatably frictioned, within the tube of the gun; - a second bush of telescopic prolongation having an internal thread and an external thread that connects with said internal thread of said bush, in order that when it rotates it is obliged to move axially in respect to the first bush;

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- a third bush of telescopic prolongation threaded externally and with internal slot to receive an internal telescopic rotational arm of rotational guide that, keyed in a base motorization within the tube of the gun, rotates said third bush and as a consequence of said threaded connections, it develops axially or re-enters telescopically, while on overcoming a certain resistance, the first threaded bush, overcoming the respective frictioning, turns without necessarily having an axial movement. In this way obtaining the advantage of maximum compacting with respective security function integrated, that avoids the overloading of the motorization when the extrusion push exceeds a certain limit. Advantageously the extremity of the telescopic piston has a rotatably free connection means being the piston head. In this way one has the advantage of not engraving rotatably on the base thrust. Just as advantageously said first bush is rotatably frictioned in a ring fashion by means of friction on an adjustable breaking device, where the annular friction is made by means of grooves or incisions that cooperate with a sphere, pushed by an adjustable spring, in order that said sphere penetrating in said grooves or incisions determines a rotation with a release as well as a determined resistance to the telescopic development. In this way one has the advantage of a regulation of the friction and additionally of a release advancement that clearly warns the operator of the existence of the overload because the external bush is in rotation. Just as advantageously said motorization includes an electric

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motor and a reducer with driving system such that: • in extrusion, operates said reducer; • in re-entry operates said small motor without the intervention of said reducer. In such a way a reversible electric motor is not necessary inasmuch the same reducer can act as such, and it requires less effort and has greater precision and ease of extrusion, with the advantage of the fast re-entry. Just as advantageously the command of said motorization is carried out by means of double trigger in said gun, by means of: - a first trigger from the handle side for the command of the ratiomotor system for the exit of the telescopic extrusion piston, an d - a counter-trigger from the opposite side for the return of fast re- entry in direct drive of said motorization. In this way the command of extrusion and re-entry is simplified and with the independent driving systems placed infront and behind the finger. These and other advantages will appear from the successive illustrative preferential solutions description of realization in connection with the included drawings. Figure 1 is a schematic section view of the extruder with the respective cartridge fixed in the cartridge carrier for the extrusion operation. Figure 2 is an exploded view of the extruder. Figure 3 is a partial view of the telescopic development system of the piston of the extruder, in which the arm with telescopic rotational development is made in a variation if compared to the

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preceding solutions, in three elements instead of in two and reversed. Figures 4 and 5 represent in a frontal and side view the first rotational frictioned bush in semi-section for the visualization of its internal thread. Figures 6 and 7 represent in a frontal and side view the second telescopic development bush from within the first, in semi-section for the visualization of its internal and external thread. Figures 8 and 9 represent in a frontal and side view the third telescopic development bush from within the second, in semi- section for the visualization of its external thread and its axial holing formed to receive the arm with telescopic development that sliding axially determines the respective rotation. The Figures 10 and 11 represent in a frontal and side view the arm with telescopic rotational development in the first and preferential realization version with two telescopic elements, that inserted within the third bush and keyed to the electric motorization determines the rotation for the telescopic or retraction development. More particularly the figure discloses that: 1 indicates the gun extrusion. 2 the respective motorization within tube 15. 3 the telescopic piston. 4 the interchangeable rotational head of the piston. 5 the cartridge carrier having the bayonet 52 connection system. 7 the cartridge with respective extrusion spout 71. The friction system is set to act on the external dented ring with grooves 311 of the first bush 31. It is disposed under the mouth

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of the tube of the gun 15 by means of the adjustable device 11 that includes: a small sphere 110 pushed by a spring 111 by means of adjustable screw 112 on threaded bush 113. Motorization 2 includes a small electric motor 21 and a reverser reducer 22 with keying 23 to the tortional telescopic arm 30, by means of connection 3011, to two tubes 301 and 302 and its extremity 3021 fits in by free axial sliding within the axial cavity 330 of the third bush 33 of the telescopic piston group 3 that includes the three telescopic bushes 31,32,33 in threaded coupling of axial movement respectively: - threaded external portion of the second bush 321 with internal th d of the first 310; - threaded external portion of the third bush 331 with internal thread of the second 320. Motorization 2 is commanded with a technically known electric system, by means of two triggers: - a first from the handle side (under the finger) 122 for the starting of the small electric motor 21 geared with the ratiomotor 22 for the rotation in one direction and therefore telescopic development (exit of the piston (3); - the second from the opposite side (above the finger) 121 that determines the direct drive of the small electric motor 21, in the opposite direction and therefore fast re-entry. The battery 131 is mounted within the handle 13 of gun 1. In this extremely simply way one obtains a gun extrusion which is maximally reliable, compact and robust, simple and rapid to operate.

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