Driving Tool for Driving Fastening Means into Workpieces

A driving tool for driving fastening means into workpieces comprising          a drive device in a housing,     an outlet tool protruding from the lower end of the housing with a driving channel,     a driving tappet that projects into the driving channel and is connected at the top to the drive device,     a magazine for fastening means that is attached to the driving channel in order to supply fastening means to the driving channel, and     a nail centering at the bottom on the outlet tool that has a centering opening that is limited by guide elements movable in the radial direction that are pretensioned toward the centering opening by at least one spring device,     characterized in that           the nail centering comprises a centering housing in which at least one circle of balls is arranged, between which the centering opening is defined, and       the spring device is an elastic ring that under pretensioning abuts the balls on the outside.

The invention relates to a driving tool for driving fastening means into workpieces.

Driving tools of the type according to the invention have a drive device in a tool housing and an outlet tool protruding from the lower end of the tool housing with a driving channel. A driving tappet projects into the driving channel and is connected at the top to the drive device. A magazine for fastening means is attached on the side to the driving channel in order to supply fastening means to the driving channel. When driving in nails or pins, a crooked alignment of the fastening means in the driving channel can cause an error in the alignment of the fastening means in the workpiece. This can be based on the fastening means partially filling the driving channel and being insufficiently guided. Moreover, in the case of nails, the nail tip can tip in relation to the wider nail head.

Driving tools with a nail centering on the lower end of the outlet tool are already known. In this case it is two flaps mounted in a hinged manner on the lower end of the outlet tool that are hinged together by springs. In the hinged together position, a centering opening is present between the two flaps. The nails being discharged from the driving channel are centered in the centering opening, wherein the flaps hinge away from each other somewhat when the wider nail head passes through. The centering opening has an oval cross-section shape for centering nails with different diameters. The disadvantage is that the springs fatigue differently so that the flaps are pressed together unevenly and centering errors occur. Moreover, the same nail centering can only be used for nails with slightly different diameters. Finally, the placement of the outlet tool onto a workpiece hinders the rebound of the flaps.

Against this background, the object of the invention is to provide a driving tool with a better centering of nails, pins and similar fastening means.

The object is solved by a driving tool with the features of claim1. Advantageous embodiments of the driving tool are specified in the dependent claims.

The driving tool according to the invention for driving fastening means into workpieces comprisesa drive device in a housing,an outlet tool protruding from the lower end of the housing with a driving channel,a driving tappet that projects into the driving channel and is connected at the top to the drive device,a magazine for fastening means that is attached to the driving channel in order to supply fastening means to the driving channel, anda nail centering at the bottom on the outlet tool that has a centering opening that is limited by guide elements movable in the radial direction that are pretensioned toward the centering opening by at least one spring device,characterized in thatthe nail centering comprises a centering housing in which at least one circle of balls is arranged, between which the centering opening is defined, andthe spring device is an elastic ring that under pretensioning abuts the balls on the outside.

When a nail, pin or similar fastening means is driven into a workpiece, the fastening means enters with its shaft into the centering opening of the nail centering after being discharged from the driving channel. When the shaft passes through the centering opening, the balls are pushed apart from each other radially against the effect of the elastic ring so that the shaft is centered. When the following nail head passes through, the balls are pushed farther apart from each other. When the fastening means has passed through the centering opening fully, the ring pushes the balls together again. The simultaneous abutment of multiple balls against the fastening means achieves a particularly exact centering. Moreover, fastening means with greatly differing diameters can be centered with the same centering device. Even as the ring gradually fatigues, the balls are pushed evenly against the fastening means and centering errors are avoided. A further advantage consists in that the outlet tool can be placed onto the workpiece with the underside of the centering housing in order to ensure an even driving depth and an alignment of the fastening means perpendicular to the workpiece surface.

According to one embodiment of the invention, the elastic ring is a snap ring. According to other embodiments, it is an O-ring or a Seeger circlip ring.

According to one embodiment of the invention, concentrically arranged circles of balls are arranged in the centering housing in at least one plane, wherein the centering opening is defined by the balls of an inner circle, the balls of an outer circle abut the balls of an inner circle, and a pretensioned elastic ring abuts the balls of an outer circle. The balls of the outer circle hereby serve to transfer the force exerted by the snap ring to the balls of the inner circle. This favors the use of elastic rings with a large diameter, long spring deflections and the usage of fastening means with different diameters.

According to another embodiment, the balls of the circle bordering the centering opening abut each other. This is the case in the initial state of the nail centering when no fastening means is discharged through the centering opening. This allows a simple construction of the nail centering. For adapting to the dimensions of the used fastening means, corresponding abutment surfaces of the centering housing can ensure in other embodiments that the balls do not abut each other in the initial state.

According to another embodiment, the balls from concentrically arranged circles abut each other on their equators. This is advantageous for the transfer of force.

According to another embodiment, the ring abuts the equator of the balls of a circle on the outside. This is also advantageous for the transfer of force.

According to another embodiment, the nail centering has multiple circles of balls arranged over each other that each border a centering opening. As a result, a fastening means being discharged through the nail centering is centered at two regions spaced apart from each other in the axial direction. A particularly exact centering is hereby achieved.

According to another embodiment, the nail centering has at least one arrangement of exactly two circles of balls arranged over each other and/or at least one arrangement of exactly two concentric circles of balls.

According to another embodiment, the centering housing is circular disk-shaped, has a central centering channel and in at least one plane multiple radial ball guiding channels that each start from the outer circumference of the centering housing and terminate in the centering channel, balls are arranged in the ball guiding channel, the centering housing has a circumferential groove on the outer circumference that cuts the outer ends of multiple ball guiding channels, and an elastic ring that under pretensioning abuts multiple balls on the outside is inserted into the groove, whereby balls between which the centering opening is defined are partially pushed into the centering channel. This embodiment is particularly easy to implement and robust from a constructive point of view. In the groove, the ring is centered in relation to the centering channel. Balls are spared by the radial ball guiding channels. According to another embodiment, the centering housing has exactly three ball guiding channels in each plane in which balls are arranged.

According to another embodiment, the centering housing has at least one radially extended threaded bore that is extended starting from the outer circumference to an extension on the upper end of the centering channel, the lower end of the outlet tool is inserted into the extension, and a clamping screw is inserted into the threaded bore by means of which the centering housing is firmly clamped on the outlet tool.

This achieves a particularly simple and reliable fixing of the nail centering on the outlet tool.

According to another embodiment, the underside of the centering housing is the lower end of the outlet tool, with which the pressing cylinder can be placed onto the workpiece. According to another embodiment, the underside of the centering housing is annulus-shaped. Marks from the outlet tool on the workpiece are hereby avoided since the centering housing can be placed onto the workpiece with a large area. Furthermore, driving in the fastening means perpendicular to the workpiece surface is promoted by the large-area abutment of the centering housing.

According to another embodiment, O-rings are arranged between the balls of an inner circle and the balls of an outer circle. Different diameters of mentioned balls and snap rings can hereby be compensated.

According to another embodiment, the drive device is designed so that it is driven by means of compressed air, by gas explosion or with electrical current. These embodiments are also termed compressed air nailers, gas pressure nailers or electronailers. The nail centering can also be used for driving tools with other drive devices.

According to another embodiment, the driving tool is a driving tool that can be handled with only one hand during use (manual tool) or a driving tool held on a displacement device or a stationarily arranged driving tool. A driving tool held on a displacement device can in particular be a driving tool arranged on a portal-like, traversable woodworking bridge.

According to another embodiment, the driving tool according to the invention for driving fastening means into workpieces has the following features:a drive device with a translatorily displaceable drive element in a housing,an outlet tool protruding from the lower end of the housing with a driving channel, that has an upper opening, a side opening and a lower opening for discharging fastening means,a driving tappet that projects through the upper opening into the driving channel and is connected at the top with the drive element,a magazine for fastening means that is attached to the side opening of the driving channel in order to supply fastening means to the driving channel, anda nail centering at the bottom on the outlet tool that has a centering opening that is limited by at least one guide element movable in the radial direction that is pretensioned in the radial direction toward the centering opening by at least one spring device,characterized in thatthe nail centering comprises a centering housing in which at least one circle of balls is arranged, between which the centering opening is defined, andthe spring device is an elastic ring that under pretensioning abuts the balls on the outside.

The preceding embodiment has advantageous features of one or more of the dependent claims or of the previously described embodiments.

In the present application, the indicators “up” and “down” and indicators derived therefrom such as “above” and “below” and “vertical” and “horizontal” refer to an orientation of the driving tool with the main cylinder over the pressing cylinder and the lower opening of the outlet tool on the lower end of the driving tool.

According toFIG. 1, a driving tool1is arranged on a bridge2above a workpiece3. Only a horizontal support of the bridge2is shown. Overall, the bridge is portal-shaped, wherein the two vertical posts are guided displaceably in the horizontal direction on rails on both sides of a workbench.

According toFIGS. 1 and 2, the driving tool1comprises a main cylinder4in a housing5, a pressing cylinder6arranged beneath the housing5, an outlet tool7protruding downwards from the underside of the pressing cylinder, and a magazine8arranged to the side of the outlet tool. The pressing cylinder6has an outwardly protruding flange6.1at the top.

The main cylinder4is designed circular-cylindrically or ovally on the inside. The main cylinder4is closed at the top by a lid9. In a central, hexagonal recess10in the underside of the lid9, the hexagon head of a first screw11sits, the threaded shaft of which passes through a central bore in the lid9and protrudes from the lid9at the top. The first screw11serves for fastening to the bridge2.

A piston12is guided vertically displaceably in the main cylinder4. The piston is sealed off from the main cylinder4with first and second O-rings13,14.

A piston rod15protrudes downwards from the underside of the piston12. The piston rod15is connected to the piston12by means of a second screw16.

Underneath, the main cylinder4has a sealing element17that is designed as a first floor plate. The sealing element17has a first through hole18in the center in the form of a guide bushing, through which the piston rod15passes so that it stands out from the sealing element17at the bottom.

A third O-ring is held in a groove on the outer circumference of the sealing element17that seals off the sealing element from the main cylinder4.

The piston rod15is sealed off from the sealing element17by a fourth O-ring19held in the sealing element17.

Above the piston12a first air chamber20is present in the main cylinder4and below the piston12a second air chamber21is present. The first air chamber20is connected to a first air inlet22accessible from the outside and the second chamber is connected to a second air inlet23accessible from the outside.

The pressing cylinder6is substantially box-shaped on the outside and has a round or oval cross-section on the inside. The pressing cylinder6has a second floor plate24at the bottom with a second through hole25.

The outlet tool7is fastened to the underside of the second floor plate24. It has a driving channel26that has an upper opening27above, a lower opening28on the lower end of the outlet tool7, and a side opening29on the side. The barrel-shaped magazine8for fastening means is attached with its output opening to the side opening29.

A driving tappet30projects with a lower section through the second through hole25and the upper opening27into the driving channel26. The upper section of the driving tappet30is fastened to the piston rod15at the bottom. For this, the driving tappet30has an external thread31at the top that is screwed into a threaded bore on the underside of the piston rod15.

A first holding device32has a first holding element33protruding radially from the piston rod15. It is hereby a circular disk-shaped projection running around the central axis of the piston rod. The first holding element33has a pot-shaped shaping34in the center into which the lower end of the piston rod15is inserted. The driving tappet30passes through a central hole of the shaping and is screwed into the piston rod15. A collar35on the outer circumference of the driving tappet30abuts the underside of the shaping34so that the first holding element33is fixed between the piston rod15and driving tappet30.

The first holding device32has a second holding element36connected to the pressing cylinder6. The second holding element36is a projection protruding radially to the inside from the pressing cylinder6. This projection is designed as an annular disk that is arranged vertically displaceably in a first expansion37on the upper end of the pressing cylinder6.

A first stop device38has a first stop element39connected to the piston rod and a second stop element40connected to the pressing cylinder6. The first holding element33is simultaneously the first stop element39. The second stop element40is a ring that is held by a setting device41near the second floor plate24.

The setting device41comprises an adjusting ring42that has an internal thread43into which the second stop element40is screwed with an external thread44. In the region of the external thread44, the second stop element40has a reduced outer diameter.

The underside of the adjusting ring42abuts the upper side of the second floor plate24. At the top, the adjusting ring42is guided on a shoulder45of the pressing cylinder6. Accordingly, the adjusting ring42is caught between the shoulder45and the second floor plate24so that it cannot be displaced vertically but can be rotated only about the vertical axis.

The adjusting ring42has multiple first blind bores46on the outer circumference into which a pin can be inserted from the outside through a slot47in the pressing cylinder6for twisting the adjusting ring42(FIG. 1). The second stop element40has multiple vertical threaded bores48on the underside into which studs49are screwed that are axially displaceably guided in second bores24.1of the second floor plate24. The second bores24.1of the second floor plate24and the studs49form a linear guide50.

By rotating the adjusting ring42, the second stop element40can be displaced in the vertical direction since it is prevented by the studs49from rotating with the adjusting ring42.

Furthermore, a second holding device51is present that has a third holding element52connected to the piston rod15and a fourth holding element53connected to the pressing cylinder6. The fourth holding element53is a nail centering54on the lower end of the outlet tool7.

The nail centering54has a circular disk-shaped centering housing55with a vertical centering channel56that is aligned with the driving channel26(FIG. 7). In the centering housing55, two concentric circles59,60,61,62of balls63are arranged in two horizontal planes over each other in each of three radial ball guiding channels57around a centering opening58. The balls63of the two inner circles59,61arranged over each other protrude partially into the centering channel56, wherein adjacent balls63support each other and border a centering opening. Adjacent balls63of the outer circles60,62and of the inner circles59,61abut each other on their equator.

The centering housing55has on the outer circumference a circumferential groove64,65in the equatorial plane of the upper circles59,60and of the lower circles61,62respectively that reach into the ball guiding channel57in the centering housing55in which the balls63are arranged. A snap ring66,67sits in each groove64,65that pushes under elastic pretensioning against the balls63of the outer circle60,62, which then push the balls of the inner circles59,61into the centering channel56until they abut each other so that the centering opening58remains between the balls63of the inner circles59,61. In addition,0-rings68,69are arranged between the balls63of the inner circles59,61and of the outer circles60,62in order to compensate for different diameters of standardized balls63and snap rings66,67so that the balls63of the inner circles59,61each abut each other.

The fourth holding element52consists of circumferential grooves72,73arranged over each other in a lower section of the driving tappet. In the vertical section, the grooves72,73are lightly rounded, corresponding to the outer contour of the balls63of the nail centering54. The spacing of the two grooves72,73corresponds to the spacing from each other of the circles59,60,61,62that are arranged over each other.

Furthermore, a third holding device74is present that has a fifth holding element75on the main cylinder4and a sixth holding element76on the pressing cylinder6. The third holding device74comprises a magnetic coupling77that has a first magnetic coupling element78connected to the main cylinder4and a second magnetic coupling element79connected to the pressing cylinder6. The first magnetic coupling element78has circular disk-shaped permanent magnets80that are fastened by means of fourth screws81to the lower ends of first bars82that are guided in vertical first bores83of the housing5.

On the upper ends of the bars82, first disks85are fastened, by means of fifth screws84, that protrude to the outside radially in relation to the bars82. The first disks85are arranged in second expansions86of the first bores83and limit the downward displacement of the first bars82by abutting an attachment on the lower end of the second expansions86. The upward displacement of the first bars82is limited by the abutment of the permanent magnets80on the underside of the housing5protruding radially in relation to the first bars82. The fourth magnetic coupling element79is designed from a ferromagnetic material as an annular disk that is fastened to the upper end of the pressing cylinder6.

The third holding device74comprises a second stop device87that has a third stop element88on the main cylinder4and a fourth stop element89on the pressing cylinder6. The fourth stop element88is a part of the second magnetic coupling element79protruding radially to the inside and the third stop element89is the underside of the sealing element17.

The second magnetic coupling element79limits the upward displacement of the pressing cylinder6by abutting the underside of the sealing element17. Furthermore, it covers the first expansion37of the pressing cylinder6at the top and limits the upward displacement of the second holding element36. The downward displacement of the second holding element36is limited by the floor of the first expansion37.

Furthermore, a retracting device90with vertically aligned pins91is present. The pins91protrude upwards from the upper side of the second holding element36.

The pins91engage with holes92of the second magnetic coupling element79. When the second holding element36is located in the lower location, the pins91do not protrude over the upper side of the second magnetic coupling element79(FIG. 3). By displacing the second holding element36upwards, the pins91are pushed out of the holes92at the top (FIG. 2).

A holder93of the magazine8is fastened to the pressing cylinder6.

The lower end of the outlet tool7is inserted into an expansion94of the centering channel56of the nail centering54and is firmly clamped therein by means of a clamping screw screwed into a threaded bore95.

The flange6.1of the pressing cylinder6is fastened by means of sixth screws96to second bars97that are guided in vertical third bores98in the housing5.

FIGS. 1 and 2show the first driving tool1in an initial position in which the outlet tool7does not sit with the nail centering54on the workpiece3. The piston12is held by compressed air fed into the second air chamber20in the upper piston position in which it abuts the lid9. The first holding element33is lifted maximally by the piston rod15so that the second holding element36abuts the underside of the sixth holding element76. The first magnetic coupling element78is pushed away from the second magnetic coupling element79by the pins91.

According toFIG. 3, the piston12and therefore the first holding element33is displaced downwards by feeding compressed air into the first air chamber20and ventilating the second air chamber21. With the first holding element33, the second holding element36and therefore the pressing cylinder6travels downwards until the outlet tool7sits with the nail centering54on the workpiece3. A defined initial location for driving a nail99or another fastening means into the workpiece3is hereby given.

Afterwards, according toFIG. 4, further compressed air is introduced into the first air chamber20and a nail99fed into the driving channel26from the magazine8is driven into the workpiece3until the first stop element39abuts the second stop element40. Then the nail99is driven into the workpiece3to a defined penetration depth. The penetration depth is determined by the vertical location of the second stop element40that can be set from the outside by twisting the adjusting ring42.

When a nail99is discharged from the driving channel26, the nail shaft is centered by the circles59,60,61,62of balls63so that it just penetrates vertically into the workpiece3.FIG. 4shows the driving tool with a nail99driven in to the given penetration depth. The lower part of the driving tappet30also hereby engages with the centering channel56. The balls63of the two inner circles59,61engage with the two grooves72,73and are held firmly therein by the snap rings66,67.

According toFIG. 5, the following upward displacement of the piston12over the nail centering54results in the outlet tool7and the pressing cylinder6also being lifted away upwards until the first magnetic coupling74couples.

The pressing cylinder6is hindered from a further upward displacement by the abutment of the sixth holding element76against the first floor plate17and the driving tappet30is pulled out of the nail centering54. When the first holding element33hits the second holding element36, the pins91release the first magnetic coupling77. The pressing cylinder6is held firmly by the abutment of the first holding element33against the second holding element36and the second holding element36against the sixth holding element76. This is shown inFIG. 6.

After feeding a further nail99from the magazine8into the driving channel26, the driving tool1is ready for another driving process. This is shown inFIG. 2.