Nail driving tool

Abstract: The invention relates to a nail driving tool comprising a magazine (9) for the accommodation of nails (10), especially in the form of nail strips or coils, and comprising a nail transporting unit associated to the nail magazine (9) and passing the nails (10) one by one through a lateral inlet opening (2) into a drive-out channel (3) for being forced out, for example, pneumatically, and with a magnet (4) being provided in the area of the drive-out channel (3), retaining at least the respectively last nail (10₁) of a nail strip or coil, once the same is ready for being forced out, within the drive-out channel (3) until commencement of the drive-out operation, wherein the magnet (4) is located on the side of the drive-out channel (3) opposite the inlet opening (2) and/or a retaining spring (8).

Description: The present invention relates to a nail driving tool according to the pre-characterising portion of claim 1. The pre-characterising portion of claim 1 is based on the disclosure of the document US-A-4 389 012. It is known in the art from DE-A-3 901 043 to provide a nail driving tool comprising a magazine for the accommodation of nails, in particular, in the form of nail strips, and comprising a nail transport unit associated to the magazine, passing the nails one by one through a lateral inlet opening into a drive-out channel for being forced out, for example, in pneumatical manner, with a spring being provided in the vicinity of the path of transport for the nails in the area of the inlet opening which is intended to keep down the nail strip. For that purpose, the spring is located above a guide plate, exerting pressure on the nail heads from the top and acting as a pressure spring. It has proved that the last and final nail of a nail strip is thereby not retained adequately or for a sufficient length of time, for which reason, occasionally, it inadvertently slips from the nozzle of the nail driving tool. For, once the transport unit is retracted, the nail strip, temporarily, has no force of contact so that the last nail of the preceding nail strip is likely to drop inadvertently into the drive-out channel. It has further been proposed in US-A-3 596 821 to provide a fastener-driving tool with an infeed guide magnet. This magnet can be replaced by means for locating each fastener in driving position within the infeed guide bore. The locating means comprises a spring-loaded ball detent which is urged to a normal position within the infeed guide bore to engage under the head of each fastener entering the bore. The US-A-4 389 012 discloses a nail driving tool being provided with an escapement mechanism. The escapement mechanism is provided with an escapement member being operated by means of a feed piston received within a feed cylinder. During a drive stroke of the driver blade, the opposite side of the piston is subjected to pressure by way of a passage. During a return stroke of the driver blade, the passage is vented and the pressure in passage returns the piston to the static position. The escapement member is attached to the feed piston. As a result, the escape member moves together with the piston in a synchronized or timed relationship with respect to movement of the driver blade. During a drive stroke of the driver blade the stop member retracts from the feed path and the separator member enters the feed path. In addition, the separator member includes a cam surface for positively advancing the first nail along the recess towards the drive position. In order to urge an advancing fastener into the proper orientation, the separator member is provided with a resilient bumper in the form of a spring biased pin. The pin is slidably received in a recess in the separator member and is urged by a spring so that normally the nose of the pin projects outwardly from the cam surface. Advancement of the first nail of the row of nails contained in the magazine assembly is positively accomplished by the escapement mechanism. Therefore US-A-4 389 012 discloses an escapement mechanism being actively operated by means of a feed piston, wherein the escape mechanism consists of numerous, complicated components and serves the purpose to positively accomplish the advancement of the first nail of the row of nails contained in the magazine assembly. It is an object of the present invention to provide a nail driving tool of the type defined in the pre-characterising portion of claim 1, wherein the disadvantages involved with the prior art are avoided and wherein the nail is prevented from inadvertently dropping into the drive-out channel. This problem is solved by a nail driving tool as set out in claim 1. To achieve the optimum nail position within the drive-out channel, the magnet, preferably, is located at the level of the nail head of the nail to be respectively forced out. An early wear of the magnet can be avoided in that, on the side thereof facing the drive-out channel, it is provided with a protective layer. In a simple configuration, the magnet is disposed in a depression of the tool nozzle extending in a direction substantially radial to the drive-out channel. The depression may be of a blind hole type accessible from the outside, with the bottom wall thereof, forming the protective layer for the magnet. The strength of the protective layer may, for example, be in the order of 1 mm. Moreover, the positioning of the nail to be forced out, within the nail drive-out channel, can be favourably influenced in that the magnet, on the front side thereof facing the drive-out channel, has a concave shape conforming to the surface of the drive-out channel. As a result of this the forcing out of the nail in no way will be affected through the magnet. Further objects, features, advantages and fields of application of the invention will become clear from the following description of one form of embodiment with reference to the drawing. The single Figure schematically shows a nail driving tool incorporating the invention in the area of transition from the nail magazine to the nozzle thereof. The nail driving tool 1 exhibits a magazine 9 (not shown in detail) for the accommodation of nails 10 in the form of nail strips or coils. Associated to the nail magazine 9 is a nail transport unit (not shown either) moving the nails 10 one by one (from the right to the left in the drawing) through a lateral inlet opening 2 into a drive-out channel 3 for being forced out, for example, pneumatically, by means of a driver 11. Provided in the area of the drive-out channel 3 is a magnet 4 retaining at least the last nail 10₁ of a nail strip or coil in the drive-out channel 3, once the same is ready for being forced out of the drive-out channel 3, until commencement of the drive-out operation. Magnet 4 is located on the side of the drive-out channel 3 opposite the inlet opening 2. Magnet 4 is approximately at the level of the nail head 12₁ of the nail 10₁ to be respective forced out. On the side facing the drive-out channel 3, magnet 4 is covered by a protective layer 5 formed by the bottom wall of a depression 6 of the tool nozzle in the form of a blind hole. The protective layer 5 has a strength in the order of 1 mm. Moreover, located at the end of the guiding path 7 for the nails 10 leading from the nail magazine 9 into the opening 2 - apart from the a known per se clamping spring 13 acting from the top on the nail strip - is, addition to or in place of the magnet 4, a retaining spring 8 of a configuration such that the last nail 10₁ only under the push pressure of the transport unit will get into the drive-out channel 3. Hence, spring 8 can be operative both in combination with the magnet 4 or by itself. The magnet 4 and/or the retaining spring 8 will prevent the respectively last nail 10₁ from inadvertently dropping into the drive-out channel 3.

Claims: A nail driving tool comprising a magazine (9) for the accommodation of nails (10), especially in the form of nail strips or coils, and comprising a nail transporting unit associated to the nail magazine (9), moving the nails one by one through a lateral inlet opening (2) into a drive-out channel (3) for being forced out, for example, pneumatically with a magnet (4) being located on the side of the channel (3) opposite the inlet opening (2), retaining the last nail (10₁) of a nail strip or coil, once the same is ready for being forced out, within the drive-out channel (3), until commencement of the drive-out operation, characterized by a retaining spring (8) being of a configuration such that the last nail (10₁) is moved into the drive-out channel (3) only under the push pressure of the transport means, whereby the last nail (10₁) of a nail strip is reliably guided into the drive-out channel (3), the retaining spring (8) being mounted with one proximal end upon said magazine (9), the opposite free end thereof being engaged with a nail (10₂) which is disposed immediately upstream of the last nail (10₁) in the guiding path (7). A nail driving tool according to claim 1, characterized in that the magnet (4) is located at the level of the nail head (12₁) of the nail (10₁) to be forced out. A nail driving tool according to claim 1 or 2, characterized in that the magnet (4), on the side thereof facing the drive-out channel (3), is provided with a protective layer (5). A nail driving tool according to any one of claims 1 to 3, characterized in that the magnet (4) is disposed in a depression (6) of the tool nozzle extending in a direction substantially radial to the drive-out channel (3). A nail driving tool according to claim 4, characterized in that the depression (6) forms an externally accessible blind hole the bottom wall of which form the protective layer (5) for the magnet (4). A nail driving tool according to claim 5, characterized in that the strength of the protective layer (5) is about 1 mm. A nail driving tool according to any one of claims 1 to 6, characterized in that the magnet (4) on the front side thereof facing drive-out channel (3) exhibits a concave form conforming to the surface of the drive-out channel (3).

Inventors: HARTMANN GERHART C O KEIL SCHA, SCHAEFER MANFRED C O KEIL SCHA, SCHNEIDER ALFRED C O KEIL SCHA, TACKE HORST C O KEIL SCHAAFHAU, HARTMANN, GERHART, C/O KEIL & SCHAAFHAUSEN, SCHAEFER, MANFRED, C/O KEIL & SCHAAFHAUSEN, SCHNEIDER, ALFRED, C/O KEIL & SCHAAFHAUSEN, TACKE, HORST, C/O KEIL & SCHAAFHAUSEN, Hartmann, Gerhart, c/o KEIL &amp; SCHAAFHAUSEN, Schäfer, Manfred, c/o KEIL &amp; SCHAAFHAUSEN, Schneider, Alfred, c/o KEIL &amp; SCHAAFHAUSEN, Tacke, Horst, c/o KEIL &amp; SCHAAFHAUSEN
Applicants: ITW BEFESTIGUNGSSYSTEME, ITW BEFESTIGUNGSSYSTEME GMBH
Application year: 1991
Main classification: B25C1
IPC codes: B25C1, B27F7