PORTABLE PERFORATING UNIT

Abstract: The portable perforating unit, particularly for sheet metal work, comprises: an outer casing (1) provided with a handgrip (2); a tool (4) consisting of a punch axially mobile between a rest position, in correspondence with which it is completely housed within said casing (1), and a working position, in correspondence with which its end emerges from said casing (1); means which, when activated by the operator, cause the impelling displacement of the tool (4) from its rest position to its working position, and to then return to its rest position.

Description: HJBTAHLE PEHSOEATIUG UNIT This invention relates to a portable perforating unit, particularly for sheet metal work. In order to make holes, in particular in sheet metal, it is known to use drills or punching machines. Drills are generally provided with a tool, knov/n as a drill bit, mounted in a chuck rotated by an electric or pneumatic motor. However, they have certain drawbacks, and in particular: - they are highly uncon ortable to operate in determined positions, for example when making holes in sheet .metal located a certain height above the operator, - they are operationally slow, the operator can be harmed by the drillings formed during working, the tool is subjected to considerable wear and is easily broken, it is impossible to form non-circular holes, a certain pressure has always to be exerted in order to make the hole. Punching machines generally comprise a tool, - commonly known as a punch, and a die on which the sheet metal in which the hole is to be made is rested. - 2 - These machines, v/hich enable holes of any profile to be- made, have however other drav/backs and in particular operational slov/ness, the need for the workpiece in which the hole is to be made to be placed on the actual punching machine, which is nearly alv/ays fixed, and the impossibility of using the die in the case of tubes or closed sections. An object of the invention is to obviate the drav/backs jointly or separately present in knov/n drills and knov/n punching machines, by providing a perforating unit which enables holes of any profile co be made at high speed. A further object of the invention is -to provide a perforating unit which is safe and reliable in use even in the most uncomfortable positions. These and further objects v/hich will be apparent from the description given hereinafter are attained according to the invention by a portable perforating unit, particularly for sheet metal work, characterised by comprising: an outer casing provided with a handgrip, - a tool consisting of a punch axially mobile betv/een a rest position, in correspondence v/ith v/hich it is completely housed within said casing, an a working position, in correspondence v/ith which its end emerges - 3 - from said casing, - means v/hich, v/hen activated by the operator, cause the impelling displacement of the tool from its rest position to its working position, and to then return to its rest position. The present invention is described hereinafter with reference to the accompanying drav/ings in which: Figure 1 is a longitudinal section through a perforating unit according to the invention in its rest configuration, Figure 2 is a view thereof similar to Figure 1 but in its working con iguration, and Figure 3 is a diagrammatic section through the valved firing mechanism of the perforating unit according to the invention. As can be seen from the ' figures, the perforating unit according to the invention comprises an outer casing 1 p: ovided with a handgrip 2 and a guiding nosepiece 3 for a punch 4. ■ - l.ithin the handgrip 2 there is provided a chamber 5, having a compressed air feed connector ύ. The chamber 5 is also provided with a valved firing mechanism 7 operated by a trigger 3 pivoted to the casing 1. - 4 - The valved firing mechanism 7 comprises substantially an opened backward cylindrical chamber 9 provided at the front end v/ith an aperture 10 crossed by a ste 11 operable by the trigger 3. A helical spring 12 acting on the inner end of the stem causes the partial exit of this from the casing 1; a suit annular ring 13, bound to the stem 11 ensure the seal between the stem 11 and its seat, and therefore the front seal of the cylindrical chamber . Inside the cylindrical chamber 9 a piston 14 is foreseen, the hollow stem 15 of which houses in the chamber 5 and is provided with a hole 16 v/hich puts said chamber 5 into communication v/ith the chamber 9 . The other end of the stem 15 houses in a seat 17 having an annular seal 13. A duct 19 outs the seat 17 into communication v/ith the rear zone of a chamber 20 housing a valve 21 , with a longitudinal hollow 22, and having its • front surface facing a cylinder 23, in which a piston 24 slides under sealed conditions. The cylinder 23, the inner diameter of which is less than the outer diameter of the valve 21 , is v/ound by an annular chamber 25 communicating with said cylinder by v/ay . of apertures 26 and 27 disposed along tv/o circumferential D ORIGINAL - 5 - lines. The position of said apertures 26 and 27 is such that v/hen the piston 24 is in its front end-of-travel position (see Figure 2), the former are disposed downstream and the latter are disposed upstream thereof. In particular, the apertures 27 consist of holes formed in a semi-cylindrical seat provided in an outer circumferential projection on the cylinder 23 and are closed by an elastic 0-rir.g 28, v/hich forms v/ith said apertures 27 non-return valves, the purposes of which is described hereinafter. The front end of the cylinder 23 is closed by an annular rubber plug 29 against which the piston 24 * halts on reaching its front end-of-travel. Inside the cylinder 23 a pin 30 is provided having its axis parallel to the axis of the same cylinder 23, for the guide of the piston 24. The piston 24 is in front provided v/itn an internally threaded cylindrical seat into which the rear flanged end 31 of the punch 4 is inserted. This flanged end 31 is held against the front surface of the piston 24 by a hollow screw 32 disposed coaxially to the punch 4 and engaged in the cylindrical seat. The nosepiece 3 comprises a shell 48 screwed on to a portion 35 which inserts into the casing 1 of the perforating unit and is bound to this by tv/o little screv/s - 6 - 44. The nosepiece 3 also comprises a cap 33 screv/ed on to a flange-shaped sleeve 34. The sleeve 34 v/ith its cap 33 are axially movable v/ith respect to the shell 43 and are kept, by means of a spring 36, projecting beyond the end of the punch 4 v/hen in its working state. A rod 37 is connected to the sleeve 34, parallel to the axis of the punch 4 and acting v/ith its back inclined plane on the end of a pushe " 33 having the other end in contact v/ith a spring lever 39. The arm 40 of the lever 39 not touching the pusher 33 drives a little rod articulated to the trigger 8. The operation of the perforating unit according to the invention is as follow: In rest state (see Figure 1 ) the pressure in the chamber 5 is transmitted through the hole 16 into the chamber 9 of the valved firing mechanism 7 and keeps the ste 1 in its back enc-of-travel, v/ith an annular seal 46 closing the way towards the duct 45- Tn this state the compressed air fills the seat 17 and, through the duct 19, can fill the rear chamber 20 of the valve 21. As the rear surface area of the valve 21 is greater than its front surface area, the valve 21 is kept pressed BAD ORIGINAL against. the rear aperture of the cylinder 23, to seal it by way of a seal ring 42. In this rest configuration, the piston 24 is at its rear end-of-travel position, and the punch 4 is completely retracted into the nosepiece 3. In order to effectively operate the trigger 3 and therefore to cause the punch 4 to go out, first of all it is necessary to rest, against the sheet metal to be perforated, the cap 33 and to cause it to go back with the flange-shape sleeve 34. Due to this displacement, the rod 37 causes v/ith its inclined plane the lowering of the pusher 33 which in its turn operates the lever 3D and put the little rod 39 into touch with the stem 11 (see Figure 2}. n operating the trigger 3, the stem 11 goes back and displaces its seal 13, and enables that the air of the chamber 9 to discharge to atmosphere through the play around the s em 11. Λs the air altering the chamber 9 through the hole 16 is lesser than the air coming out from said play, the chamber 9 has a pressure lesser than the pressure of the chamber 5- Therefore the piston 14 advances and its stem 15 closes backward, with its seal 13, the annular aperture of the seat 17, no longer allowing the inlet of the air into - 8 - the chamber 20 and at the same time causing the compressed air, there housed, to discharge through the duct 45. Uov the pressure difference betv/een the chamber 5 and the chamber 20 causes the backwards displacement of the valve 21 and its separation from the cylinder 23. The air violently enters the interior of this latter through its rear aperture, to suddenly thrust the piston 24 and the punch 4 rigid with it. After a very short distance of travel the valve 22 closes its rear aperture against the plug 43. In this manner, the compressed air from trie * chamber 5, after entering the cylinder 24, is prevented from passing to atmosphere through the axial cavity 22 of the valve 21 and the ducts 47- The sudden advancement of the piston 24 causes the air in the front part of the cylinder 23 to pass into the annular chamber 25 * through the holes 26 and 27 and to undergo com-pression. It should be noted that in this stage, in v/hich the trigger 5 is almost certainly still being pressed, when the piston 24 has reached its front end-of-travel position, the air from the chamber 5 and also the air which is still being fed through the connector 6 enter the cylinder 23 through its rear aperture, to thus - 9 - enter the annular chamber 25 through the holes 27, so increasing the pressure therein. V/hen the operator releases the trigger 3, the elastic reaction of the spring 12 returns the stem 11 to adhere v/ith the seal 13 to its seat, preventing the further exit of air through the play around the stem 11. The chamber 9 fills v/ith air v/hich, after having pushed the stem 15 to its rear end-of-travel position, enters into the chamber 20 through the duct 19. Vhen. the chambers 20 and 5 have the same pressure, the valve 22 closes the cylinder " 23 at its rear, and on the other hand enables the air accumulated in the cylinder 23 to pass through the inner cavity 22 of said valve 21 and to leave to atmosphere through ducts 47- As a result of this, the compressed air contained in the annular chamber 25 can discharge through the aperture 26 to urge the piston 24 rearwards and with it the punch 4, which is rigid therewith, this latter entering the nosepiece 3 ready for the next operation. It should be noted that during this stage the compressed air v/hich has accumulated in ' the annular chamber 25 is unable to leave through the aperture 27 because of the presence of the 0-ring 28. V/hen the piston 24 is in its rear end-of-travel - 1 0 - position, the further compressed air housed inside the cylinder 23 comes out through the several plays present betv/een the reciprocally moving parts. As this air has been previously added with oil, it lubricates the several parts. As already said, the operating of the trigger 8 requires the preventive backwards displacement of the cap 33 and therefore the operating of the perforating unit is not allowed in the case in v/hich the cap 33 has not been rest against the metal sheet to be perforated. If moreover, due to accidental reasons, such an operating of the trigger will equally occur and cause the operating of the perforating unit, the cap 33 of the nosepiece 3, v/hich elastically projects forwards by an extent greater than the emerging portion of the punch 4, would be in any case a further "safety". Because the tool needs to be periodically resharpenea with use, and the effect of the resharpening is to shorten it, it is necessary occasionally to screw the cap 33 around the sleeve 34 to maintain the punch portion projecting thereform constant. V/hen it is no longer possible to resharpen the punch 4 and it thus has to be replaced, the nosepiece 3 is disengaged from the member 1 by operating on the screws 44. - 1 1 - The hollow screv/ 32 is then disengaged from its seat in the piston 24, . the punch 4 = is withdrawn therefrom and is replaced v/ith a new one. From the aforegoing it is clear that the perforating unit according to the invention has numerous advantages, and in particular: it enables holes of any profile to be quickly formed; it should be noted that the slight deformation of the perforated metal sheet around the hole is insignificant as the edge of the hole is generally covered by a washer or by the ' neac of the screv/ v/hich is to be inserted through the hole, - it is safe and reliable in use, even in a very uncomfortable position, as it requires practically no pressure to be exerted against the surface of the sheet metal to be perforated, - it cannot harm the operator, as the punch emerges from the nosepiece only when this is rested against the v/orkpiece to be perforated, - ic car alόo be u_. d for perforating tubes or closed sections. From tests carried out with a perforating unit of dimensions corresponding to those of a conventional - 1 2 - commercial hobby drill, 100 holes of 5 mm diameter were made in one minute in a section 1.5 mm thick v/ithout any noticeable wear of the punch. The same test carried out v/ith a professional drill 5 of about 350 v/atts positioned on a bench and thus under more comfortable conditions for the operator, required a time of eighteen minutes. In uncomfortable positions (walls, ceilings) this time is certainly greater. o The invention can also use conventional valved firing mechanisms of other types v/hich provide for the automatic return of the piston 24 and of the punch 4 rigid therewith into their rest position, independently of whether .he trigger d has been released or not. In addition, the 5 tool for its next actuation must require the trigger 3 to be operated again. The described embodiment of the perforating unit is fed v/ith compressed air. However, the invention also covers perforating units operated by an explosive charge. This 0embodimen , which doubtlessly is more costly to produce and more noisy in use, can be preferred where compressed air feed is not available or if the thickness of the workpieces to be perforated is so large as to otherwise require - 1 3 - excessively bulky perforating units operated by compressed air. The invention also covers a perforating unit operated by electric charge. Again in this case, as in the previous case, compressed air is not required but the unit has the drawback of slov/ operation and of considerable v/eight and overall size. Finally, the invention also covers a perforating unit operated by manual charge. In this case, no external eed connection is required, but the unit has the drawback- of slov/ operation due to the need for manual recharging.

Claims: - - C L A I M S 1. A portable perforating unit, particularly for sheet metal work, characterised by comprising: an outer casing (1 ) provided with a handgrip (2), ¥ a tool (4) consisting of a punch axially mobile between a rest position, in correspondence with which it is completely housed within said casing (1 ), and a working position, in correspondence with which its end emerges from said casing (1 ), - means v/hich, when activated by the operator, cause the impelling displacement of the tool (4) from its rest position to its working position, and to then return to - * its rest position. 2. A perforating unit as claimed in claim 1, characterised in that the punch (4) is mounted on a piston (24) mobile axially within a cylinder (23) by pneumatic action. 3. A perforating unit as claimed in claim 2, characterised in that within the casing (1 ) there is provided a compressed air receiver (5) feedable from the outside and arranged to operate the piston (24) by a valved firing mechanism (7) controlled by a trigger (3). 4. A perforating- unit as claimed in claim 3, 5 characterised in that the valved firing mechanism (7) is provided with an inlet (16) connected to the compressed air receiver (5) and with two outlets, the first oulet being connected to the operating members of the piston (23), and the second outlet oeing connected to atmosphere, the trigger (8) v/hen released resulting in the opening of the inlet and of the first outlet and the closure of the second outlet, whereas the trigger (8) whe activated resulting in the closure of the first oulet and the opening of the second outlet. 5. A perforating unit as claimed in claim 4, characterised* in that the valved firing mechanism (7) comprises an opened cylindrical chamber ( 9 ) provided at the front end v/ith an opening (10) crossed by a ste (11 ) axially operable by the trigger (ό) and acting on the second outlet, inside said chamber (9) a piston (14) being foreseen the stem (15) of v/hich acts on the first outlet. 6. A perforating unit as claimed in claim 5, characterised in that the first outlet of the valved firing mechanism (7) communicates with a seat (17) with which also two ducts (19, 45) communicate, respectively connecting said seat (17) to the operating members of the piston (24) and to atmosphere, said ducts (19, 45) communicating to each other BAD ORIGINAL ' when the trigger ( 8 ) is operated. 7. A perforating unit as claimed in claim 2, characterised in that the cylinder (23) is provided at its rear end with a valve (21 ) mobile between two end positions, 5 in one of which the cylinder (23) communicates with the compressed air receiver (5) to cause the piston (24) to undergo its working stroke, whereas in the other of which the cylinder (23) communicates v/ith atmosphere to allow the piston (24) to undergo its return stroke. θ 8. A perforating unit as claimed in claim 7, characterised in that the valve (21 ) is mobile in a sealed mariner within ' a cylindrical chamber (20) coaxial to the cylinder (23) and is fed at its rear, through the duct (19) connected to the valved firing mechanism (7). 5 9. A perforating unit as claimed in claim 2, Characterised by comprising an air spring t 25. loadable during the working stroke of the piston (24) and arranged to elastically return said piston to its rear end-of-travel position -for repeating the operating cycle. 20 10. . . A perforating uni as claimed in claim 9, characterised in that the air spring consists of an annular chamber ( 25 ) surrounding the cylinder ( 23 ) and communicating therewith by way of at least one aperture (26) provided in " . - the wall of said cylinder in a position forward of the front end-of-travel position of the piston (24). 11. A perforating unit as l claimed in claim 10, characterised in that the inner chamber of the cylinder (23) also communicates v/ith the annular chamber (25) by v/ay of at least one aperture (27) which is formed in the wall of said cylinder in a position rearward of the front end-of-travel position of the piston (24), and is provided v/ith a non-return valve ( 23 ) v/hich prevents air passing from said cna ber (25) to said cylinder (23). 12. A perforating unit as claimed in .claim 1 , characterised by comprising a nosepiece ( 3 ) for guiding the tool (4), whicn when in its rear end-of-travel position is completely housed within said nosepiece (3), whereas when in its front end-of-travel position its end portion emerges there om. 13 A perforating unit as claimed in claim 12, characterised in that the nosepiece ( 3 ) comprises an inner portion (35) bound to the casing (1 ) and an outer cap " (33) axially adjustable in order to ensure that the emerging portion of the tool is constant independently of the length of this latter. 14. A perforating unit as claimed in claim 13, characterised in that the cap ( 33 ) is screv/ed on to a * flange-shaped sleeve (34) axially movable v/ith respect to a shell (48) winding them. 15. A perforating unit as claimed in claim 14, 5 characterised in that the cap (33) and the sleeve (34) are elastically kept projecting beyond the end of the punch (4) when in its front end-of-travel condition. 16. A perforating unit as claimed in claims 14 and 15, characterised in that the nosepiece (3) is provided with a 0 safety device not allowing the operating of the valved firing mechanism (7) v/hen the sleeve (34)' is in its front end-of-travel condition. 17- A perforating unit as claimed in claim 16, characterized in that to the sleeve (34) a rod (37) is 5 connected parallel to the axis of the punch (4) and acting v/ith an its back inclined plane on the end of a pusher (33) having the other end in contact with a spring lever (39) v/hich allows the operating of the valved firing mechanism (7). 2018. A perforating unit as claimed in claim 2, characterised in that inside the cylinder ( 23 ) a rod (30) is housed having its axis parallel to the axis of the cylinder for guiding the piston (24). - IS ' 1 . A perforating " unit as claimed in claim 2, characterised in that the piston (24) is provided at its front with an internally threaded cylindrical seat into which there is screwed a hollow screv/ (32) through which the tool (4) passes, this latter being provided with a terminal flange ( 31 ) and being retained in this seat by the rear edge of said hollow screw (32) resting against said flange (31 ).

Inventors: SIMONI RENZO, SIMONI, RENZO
Applicants: SIMONI RENZO, SIMONI, RENZO
Application year: 1986
Main classification: B21D28
IPC codes: B21D31, B26D5, B26F1