EP0018272A1 - Power controlled stud-driving tool - Google Patents

Abstract

A power adjustment for a piston-type powder actuated fastener driving tool wherein a tube is slidably disposed in the barrel of the tool, the tube containing the driving piston of the tool. The tube has a radially inwardly extending flange at its breech end which engages a radially outwardly extending surface on the piston. Means for moving the tube axially of the barrel are provided so that the distance between the flange and firing chamber can be varied whereby the gas expansion chamber between the firing chamber and the rear face of the piston can be varied thereby varying the power with which the piston is driven.

Description

The invention relates to an apparatus for sealing fasteners, comprising a barrel holder, a cylinder head secured to the barrel holder, a barrel mounted to slide in the breech, a counterweight mounted to slide in the barrel, and a tip guide, the rear end of the tip guide being in contact with the front end of the barrel.

Many devices of this type are already known. However, in these, the variation in the initial volume of the combustion chamber which determines the power with which the counterweight is driven by the combustion gases, which counterweight in turn causes a fastening element to move in a material intended for to receive it, is obtained using relatively heavy means.

The present invention aims to improve such weights sealing devices by providing a simple power variation device, easy to perform and allowing a large power variation range with large degrees of freedom for the structure of the device.

To this end, the present invention relates to a sealing device of the type mentioned above, characterized in that it comprises a power adjustment ring mounted screwed on the tip guide and on the barrel holder, the ring and the front part of the barrel being arranged to cooperate together so that the rotation in one direction of the ring causes the barrel to slide towards the front of the device, while the rotation of the ring in the other direction causes the barrel slides backwards under the action of the tip guide.

Thanks to the invention, it suffices to rotate the power adjustment ring to vary in one direction or the other the initial volume of the combustion chamber and therefore the firing power.

In one embodiment of the invention, the barrel is fixed in rotation and has a groove in which a finger can protrude from a return pawl of the counterweight. In this case, the power adjustment of the device of the invention is advantageously combined with a reminder of the counterweight in the firing position.

• - La figure 1 représente une coupe longitudinale de l'appareil de l'invention, le sous-ensemble de canon étant représenté dans sa position la plus avancée ;
• - La figure 2 représente une vue en coupe de l'appareil de la figure 1 dans sa position prête au tir, et
• - La figure 3 représente l'appareil des figures précédentes avec le sous-ensemble de canon juste avant sa position verrouillée.

The invention will be better understood with the aid of the following description of a preferred embodiment of the invention with reference to the appended drawing, in which:

• - Figure 1 shows a longitudinal section of the apparatus of the invention, the barrel sub-assembly being shown in its most advanced position;
• FIG. 2 represents a sectional view of the apparatus of FIG. 1 in its position ready for shooting, and
• - Figure 3 shows the apparatus of the previous figures with the barrel sub-assembly just before its locked position.

The apparatus of the invention, referenced 2 in the drawing, comprises a counterweight 4 which can be driven in displacement under the action of the combustion gases produced by a cartridge 6 in order to drive a fixing element, not shown, in a material intended to receive it.

The device 2 comprises a case 8 in which is disposed a gun holder 10 screwed onto a cylinder head 12 in the form of a ring. Inside the barrel holder 10 is disposed a barrel 14 in the bore 16 of which the counterweight 4 is slidably mounted. The barrel 14 is slidably mounted in a bore 18 formed in the cylinder head 12. The barrel 14 has a longitudinal groove 20 in which a finger 22 can protrude from a counterweight return pawl 24 pivotally mounted. The end of the groove 20 disposed near the tip guide of the apparatus, which will be discussed below, is chamfered so as to have a cam surface, or ramp, 26 arranged to cooperate with the finger 22 and thus remove it from the groove when the device is supported.

The barrel 14 has at its end close to the tip guide a flange 28 extending radially outward and cooperating with a flange 30 extending radially inward formed on a power adjustment ring 32. The ring 32 is screwed inside the end of the barrel holder 10, close to the tip guide, and has an enlarged portion 34 forming a shoulder 36 cooperating with a surface 38 formed at the end, close to the tip guide, of the holder -canon 10, when the ring 32 is screwed completely into the barrel holder 10. A tip guide 40 is screwed into the ring 32 and comprises a ring 42 screwed firmly against the end 44 of the ring 32 facing outwards of the device. The inner end 46 of the tip guide 40 is disposed in contact with the end 48, directed towards the tip guide, of the barrel 14. A lock 50 is pivotally mounted under the action of a spring on the end, close to the tip guide, the bootmaker 8 and has a finger 52 extends dant inside a locking notch 54 formed at least at the end, near the tip guide, of the gun holder.

The counterweight return pawl 24 is pivotally mounted against the action of a spring at the end, directed towards the tip guide, of a rod 56 which extends through a bore 58 formed in the barrel holder 10, a bore 60 formed in the cylinder head 12, and a bore 62 formed in the case 8, the rod 56 having a threaded end 64 extending through a bore 66 formed in an operating cover 68 covering the rear end of the bootmaker 8. A bolt 70 is screwed onto the threaded end 64 of the rod 56 to hold this rod 56 in place.

As will be seen below, the device 2 can be disassembled, for example to be cleaned, by actuating the latch 50 and removing the bolt 70. A chamber support plate 72 is mounted in the case 8 and has a boss 74 extending forward, in which a combustion chamber 76 is formed.

It will be noted that the barrel holder 10, the breech 12, the barrel 14, the adjustment ring 32 and the tip guide 40 form a sub-assembly which can slide axially over a limited distance inside the boot 8. Figure 1, this sub-assembly is shown in its most advanced position in which it is recalled by a spring 78 which surrounds a portion of the rod 56 which is contained in a bore 80 of the case 8. The extreme movement of this advanced position is limited by the finger 52 of the latch 50 cooperating with a rear wall 82 of the notch 54. It should be noted that when this sub-assembly is in its most advanced position, a distance G separates the rear wall 84 from the cylinder head 12 and the front wall 86 of the chamber plate 72. It should also be noted that the chamber plate 72 is provided with a bore 88 opening onto the rear end of the barrel bore 16 and the rear face 5 of the counterweight 4. The bore 88 is dimensioned so that the boss of the combustion chamber 74 can be introduced in the bore 88 during the setting down of the device when the device is ready for firing, as shown in FIG. 2.

With reference to FIG. 2, the apparatus 2 is shown in the ready-to-fire position, position in which the power level of the apparatus is at its maximum and in which the rear face 5 of the counterweight 4 is in its position closest to the front end surface 75 of the boss of the combustion chamber 74. Thus, the gas expansion chamber 90 occupies a minimum volume. wherein the combustion gases produced by the cartridge can relax before the flyweight is entrained in the bore 16 of the barrel. The dimensions of the expansion chamber 90 are determined by the cooperation of the rear face 5 of the counterweight 4 with the front face 15 of an inwardly extending collar provided at the rear end of the barrel 14.

It will be noted, in FIG. 2, that when the device is in its resting position, the cam surface 26 cooperates with the finger 22 to cause the pawl 24 to pivot in a clockwise direction, by so that the finger 22 no longer protrudes inside the bore 16 of the barrel.

After firing the device, the counterweight 4 is driven into the bore 16 of the barrel, the rod 92 of the counterweight 4 passing through the bore 41 of the tip guide 40. It will be readily understood that the fixing element , not shown, intended to be driven by the counterweight, is disposed in the bore 41 of the tip guide prior to firing the device.

After firing, the device is released from the bearing face of the material intended to receive the fixing element and the spring 78 recalls the interior sub-assembly in the position shown in FIG. 1, the only difference being in the fact that the counterweight 4 is in a driven position inside the bore 16 of the barrel with its head 94 disposed behind the finger 22 of the pawl 24, so that the latter, having pivoted to protrude at the interior of the bore 16 of the barrel is in a position where it can cooperate with the front surface 95 of the counterweight head 94.

The flyweight 4 is returned to the firing position by grasping the operating cover 68 with one hand, the other hand grasping the handle 108 of the device and pulling the operating cover 68 backwards. The rod 56 is thus pulled backwards with the pawl 24. The cooperation of the finger 22 of the pawl with the surface 95 of the counterweight head causes the counterweight 4 from its position after firing to its position before firing. When the rear face 5 of the counterweight 4 comes into contact with the face 15 of the inner collar of the barrel, the rearward movement of the operating cover 68 takes place against the action of the spring 78, the counterweight 4 then having been returned to the firing position. The cover 68 of the rod 56 and the pawl 24 are then pushed forward and returned to their respective position shown in Figure 1. During the rear movement of the cover 68, the barrel holder 10 is locked in the front position by a ball 100 housed in a hole 101 formed in the cylinder head 12, / having a diameter greater than the thickness of the wall of the cylinder head 12.

When the cover 68 is in the advanced position of FIG. 3, the ball 100 is arranged in a groove 102 formed on the rod 56 allowing the movement of the barrel holder 1 When the cover 68 is pulled backwards (fig. 1), carrying with it the rod 56, the ball 100 rises and emerges from the groove 102 to come into the housing 103 formed in the case 8 thus locking the gun holder 10, the counterweight 4 then being able to be brought back into its firing position without compression of the spring 78.

The power level of the apparatus varies according to the volume of the expansion chamber 90 as follows. When the adjustment ring 32 is unscrewed forwards and out of the barrel holder 10, flange 30 drives the flange 28 of the barrel and consequently the barrel 14 itself forwards to move it away from the breech 12. In this way, the rear end wall 21 of the groove 20 and the surface 15 of the inner flange of the barrel are spaced from the breech 12. Thus, the space formed between the front end 75 of the boss 74 of the expansion chamber and the rear surface 5 of the counterweight increases. As the volume of the expansion chamber 90 increases, the combustion gases have more space and a longer time to relax before the counterweight 4 is driven, which will reduce the propulsion speed of the counterweight 4. It should be noted that when the ring 32 is again screwed into the barrel holder 10, the barrel 14 is driven longitudinally towards the rear by the tip guide 40 pushing the end 48, in contact with the guide -point, from barrel 14 and thus increasing the power level of the device.

It has been found that the power level of the apparatus 2 can thus be adjusted from a high kinetic energy level, in which a maximum counterweight kinetic energy is developed by the cartridge, up to an average energy level in which the kinetic energy of the intermediate level flyweight is developed, while only slightly moving the adjusting ring 32 over a distance of a few centimeters, without therefore varying the overall length of the device.

However, in order to be able to obtain a low firing power, there are provided one or more vents 96 (FIG. 3) which extend in the wall of the breech part 12 in which the barrel is mounted to slide and which open into a cavity 98 which is preferably isolated from the atmosphere and which is arranged between the barrel 14 and the barrel holder 10. When the ring 32 is sufficiently dimensioned from the barrel holder 10, the barrel 14 is pulled forward enough to uncover the vents 96 and thereby provide a passage for the combustion gases which can escape from the combustion chamber 90, which leads to reducing the power with which the flyweight 4 is driven. Thanks to the vents 96, the power of the device can be adjusted to a low level without having to excessively unscrew the adjustment ring, or to excessively lengthen the whole device.

By appropriately positioning and sizing these vents, a wide range of power variations is obtained with large degrees of freedom for the structure of the apparatus, in which high, medium and low power levels can be obtained.

The device 2 can easily be dismantled by unscrewing and removing the bolt 70. The lock 50 is then actuated to pivot in a counter-clockwise direction, so as to release the finger 52 from the locking notch 54. The whole sub-assembly, comprising the barrel holder 10, the cylinder head 12, the barrel 14, the adjustment ring 32 and the tip guide 40, can then slide out of the case 8.

The device is reassembled by reintroducing the sub-assembly in the housing 8, the lock 50 being maintained in the retracted non-locking position. The bolt 50 is then released and the bolt 70 is screwed back onto the projecting end 64 of the rod 56.

Claims (4)

1. Apparatus for sealing fasteners, comprising a gun holder, a cylinder head secured to the gun holder, a gun mounted sliding in the breech, a weight mounted sliding in the barrel, and a tip guide, the end rear of the tip guide being in contact with the front end of the barrel, apparatus characterized in that it comprises a power adjustment ring mounted screwed on the tip guide and on the barrel holder, the ring and the part front of the barrel being arranged to cooperate together so that the rotation in one direction of the ring causes the barrel to slide towards the front of the device, while the rotation of the ring in the other direction causes the barrel to slide backwards under the action of the tip guide. 2. Apparatus according to claim 1, characterized in that the front part of the barrel comprises a flange cooperating with a flange formed in the rear part of the ring. 3. Apparatus according to one of claims 1 and 2, characterized in that the wall of the breech portion in which the barrel is slidably mounted has vents. 4. Apparatus according to one of claims 1 to 3, characterized in that the barrel is fixed in rotation and has a groove in which a finger can protrude from a return pawl of the counterweight.

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