Patent Description:
<CIT> relates to a fastening tool which controls the return behavior of a driver blade by using a blade stop and/or a bumper. The fastening tool can remove the driver blade from the drive path upon its return after driving a fastener into a workpiece and bring the driver blade to a resting state by using a bumper to orient the driver blade out of alignment with the drive path and into contact the driver blade stop. <CIT> relates to a reaction absorbing device for a driving machine and discloses a return bumper for receiving a piston stopped, when the piston for supporting a driving driver is retracted in a cylinder, is longitudinally movably provided in a cylinder rear part. The return bumper is always energized to an advancing position by an elastic member. A reaction absorbing valve is provided behind the cylinder, and when the return bumper is retracted by compressed air in a piston rear part chamber of the cylinder, the valve is opened in accordance with retracting action, to release partly the compressed air into the atmosphere. Thus by absorbing reaction, a driving machine is prevented from floating.

In a fastening tool, fasteners, such as nails, are driven into a workpiece by a driver blade or driver through a process known as a "drive" or "drive cycle". Generally, a drive cycle involves the driver striking a fastener head during a drive stroke and returning to a home position during a return stroke. To absorb the force of the driver movement during the return stroke, after a fastener is driven into a workpiece, bumpers are provided at the front and rear of the drive path. At the end of a drive, the driver may have residual momentum or leftover kinetic energy that compresses the front bumpers as the front bumpers absorb the force of the driver. The front bumpers will return this energy to the driver sending the driver rearward until the driver impacts the rear bumpers. A stop member and home magnet should hold the driver in the home position and prevent the driver from traveling forward toward the next fastener waiting to be driven; however, in some instances the driver retains an excess amount of kinetic energy after firing a first fastener, such that the driver bounces off of the rear bumpers with enough speed to skip over the stop member. If the driver skips over the stop member, the driver can travel forward, along the drive path, and break free the next or second fastener from a collated strip of fasteners, and push the second fastener toward the nosepiece of the fastening tool. The second fastener can be inadvertently pushed into the nosepiece while the driver is returned to the home position. A third fastener, which is intended to be driven after the driver is returned to the home position, is allowed to advance into the drive path, resulting in two fasteners in the drive path. The second and third fasteners would abut each other in the nosepiece of the tool. As such, when the tool is fired again, both the second and third fasteners will be driven simultaneously, often resulting in a misfire, nail jam, bent nails and/or damage to the fastening tool.

Accordingly, there is a need to prevent the driver from rebounding into the drive path and striking additional fasteners at the end of a drive cycle.

According to aspects of the present invention there are provided the fastening tool of claim <NUM> and the method of claim <NUM>.

In an embodiment of the present disclosure a fastening tool includes a housing having a housing interior, a forward end, a rearward end, and a support member disposed in the rearward end. The rearward end of the housing can include a rear housing cover removably attached to the housing. A drive track is defined within the housing interior and a driver is reciprocally mounted for movement within the drive track, along a fastener drive axis, to drive a fastener during a drive stroke. The driver has a blade at the front end for striking the head of a fastener during the drive stroke, and a rear end axially opposite to the front end. An elastically deformable member is operatively connected to the support member in the rearward end of the housing and bearing against a rearward end surface of the housing. A dampening member is disposed between the elastically deformable member and the rearward end surface of the housing.

The elastically deformable member, or driver rebound plate is configured to receive an impact from the rear end of the driver during a return stroke and deflect the driver out of the drive axis toward a stop member disposed at a forward end of the housing. The stop member is configured to receive the driver blade or front end of the driver in a home position. The elastically deformable member or rebound plate includes a mounting portion at a first end thereof slidingly fastened to the support member and a bearing portion at a second end thereof disposed against the rearward end surface. The mounting portion and the bearing portion are slidably movable with respect to the drive axis upon impact of the driver on the impact portion. A retaining portion is disposed adjacent to the mounting portion and includes a retaining tab that projects outwardly to wedge the dampening member between the rearward end surface and the driver rebound plate. An impact portion is disposed between the retaining portion and the bearing portion and can be bent at an oblique angle with respect to the drive axis. The impact portion can have an impact face for receiving the impact of the driver and a dampening face opposite the impact face for supporting a dampening member.

The rebound plate can be formed from a metal or alloy, including but not limited to steel. Additionally, the steel or metal can be heat-treated.

The dampening member can be formed from an impact absorbing material having a polymeric, rubber or plastic properties, including, but not limited to a foam, such as the rubber-like foam CELLASTO®.

The driver rebound plate can be an elastically deformable, elongated body of uniform thickness, formed of a heat-treated metal. The driver rebound plate can be arranged in the housing or a rear housing cover to deflect the driver blade or driver out of the fastener drive axis during a return stroke. The driver rebound plate can have a mounting portion, to mount the plate to a housing support member, at a first end thereof and a bearing portion at a second end thereof. A retaining portion is disposed between the mounting portion and the bearing portion and adjacent to the mounting portion. An impact portion is disposed between the retaining portion and the bearing portion. The impact portion can be bent at an oblique angle thereby forming a sloping surface with respect to the retaining portion. In a fastening tool, the impact portion is also configured to have an oblique angle with respect to the drive axis.

The mounting portion includes a slot to accommodate sliding movement of the mounting portion with respect to the support member. The retaining portion can be lanced to partially cut out a retaining tab. The retaining tab is bent to project outwardly and serves to prevent forward or sliding movement of the dampening member when the dampening member is in a position on the impact portion.

In an embodiment of the present disclosure, the fastening tool includes a method of a controlling rebound of the driver including providing a driver reciprocally mounted for movement within a drive track along a drive axis to drive a fastener during a drive stroke, the driver having a front end and a rear end; providing a driver rebound plate having an impact portion adapted to receive an impact from the rear end of the driver during a return stroke; providing a dampening member to absorb the impact from the driver; providing a stop member to receive the front end of the driver in a home position; guiding the driver along the drive axis to contact the driver rebound plate; deflecting the rear end of the driver out of alignment with the drive axis during the return stroke; and guiding the front end of the driver toward the stop member. The step of providing a driver rebound plate includes providing an impact portion obliquely angled with respect to the drive axis.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings.

Referring to <FIG>, a fastening tool including a rebound preventer, such as a driver rebound plate, for the fastener driver. The driver rebound plate prevents the driver from bouncing forward in the tool, toward the nosepiece, after a fastener has been driven, or the tool fired.

Referring now to the Drawings and particularly to <FIG>, a fastening tool <NUM> in accordance with an embodiment of the present invention includes a housing <NUM> and a fastener drive system <NUM> disposed in the housing. The housing <NUM> has a forward end 12a and a rearward end 12b defining a housing interior <NUM>. The fastener drive system <NUM> includes a driver <NUM> for driving fasteners along a drive path to a nosepiece <NUM>, and into a work surface. The driver <NUM> is reciprocally mounted for movement within a drive track <NUM> carried by the housing <NUM> along a fastener drive axis <NUM> to drive a fastener during a drive stroke. The driver <NUM> has a front end 16a including a driver blade for striking a fastener during a drive stroke and a rear end 16b for striking the driver rebound plate. The rear end is at an axially opposite end of the driver from the front end. The fasteners can be temporarily stored in a magazine <NUM> which is connected to the drive track <NUM> and also supported at a handle <NUM> used by an operator to manipulate the fastening tool <NUM>. The fastener drive system <NUM> also includes a motor <NUM> powered by a battery <NUM> and operatively associated with the driver <NUM> to drive the fasteners. A trigger <NUM> is manually depressed by the operator to actuate operation of the fastening tool. The battery is releasably connected to the handle and provides operative electrical power for operation of the fastening tool <NUM>.

Although the embodiments of the fastening tool of the present invention depicted in the Drawings are shown as concrete nailers, it will be appreciated that the present invention can be incorporated in any fastening tool, for example, a high-powered cordless nailer and including, without limitation, staplers and other nailers.

Before each fastener is driven into a workpiece, the driver <NUM> must be positioned in the home position as shown in <FIG>. The home position is the position wherein a front face portion or the front end 16a of the driver <NUM> is in abutment with a stop member <NUM> and is available to begin a fastener driving cycle. The stop member <NUM> is disposed at a forward end 12a of the housing and configured to receive the front end 16a of the driver <NUM> in a home position and prevent the driver from moving forward down the drive path until the fastening tool <NUM> is activated again by the operator. In a home position, the front end 16a of the driver <NUM> can be reversibly magnetically held by a home magnet <NUM> adjacent to the nosepiece <NUM>. For example, as shown in <FIG>, the front end 16a of the driver <NUM> is proximate to the home magnet <NUM>. In an embodiment, the home magnet <NUM> can magnetically attract the front end 16a toward a home seat <NUM> against which the front end 16a can rest. In other embodiments, the home position can be configured such that the driver is affected by the magnetic force of the home magnet <NUM>, but not held or in direct physical contact with the home magnet itself.

The stop member <NUM> is located in the nosepiece <NUM> of the fastening tool. In an embodiment, the stop member <NUM> can be a portion of, or a piece attached to, the nosepiece <NUM>. In an embodiment, the material used to construct the stop member <NUM> can be a hard and/or hardened material and can be impact resistant to avoid wear. Both the driver <NUM> and stop member <NUM> can be investment cast <NUM> carbonized steel. In an embodiment, the stop member can be made of case hardened AISI <NUM> steel, or other hardened material, such as used for the nosepiece, or other part which is resistant to wear from moving parts or moving fasteners.

As shown in <FIG>, to prevent the driver <NUM> from skipping over the stop member <NUM> and inadvertently traveling back down the drive path after a drive stroke, a spring-loaded body, such as the driver rebound plate <NUM> is provided in the rear portion of the tool, such as, for example, within the housing end cap or within a rear housing cover <NUM>. The rear housing cover <NUM> can be connected to the rearward end 12b of the housing <NUM> and have a cover interior <NUM> that is open to the housing interior <NUM>. The rear housing cover <NUM> can have a support member <NUM> that projects from an inner surface of the cover interior. The inner surface of the cover interior can be, for example, a rearward end surface <NUM>. Alternatively, a support member can be disposed on a surface of the rearward end 12b of the housing <NUM>. The driver rebound plate <NUM> can be can be attached to the support member <NUM> at a position that allows the driver rebound plate to receive the impact from the driver <NUM> on the return stroke. Further, the driver rebound plate can be attached to the support member <NUM> by a shoulder bolt <NUM> or other fastening means in a manner that allows the driver rebound plate to move up and down with respect to the drive axis <NUM> and/or the support member <NUM>. In an embodiment, the driver rebound plate <NUM> is an elastically deformable member operatively connected to the support member <NUM> and bearing against a rearward end surface <NUM> of the rear housing cover <NUM> or the rear surface of the housing.

As shown in <FIG>, the driver rebound plate <NUM> can be an elongated body of rectangular cross-section having a pair of flanges disposed at opposite ends of the body and a plurality of intermediate portions disposed between the pair of flanges. The flanges serve to affix the driver rebound plate <NUM> in the rear housing cover <NUM>, while the intermediate portions service to receive and support dampening of the driver impact.

<FIG> illustrates the first flange as a mounting portion <NUM> through which the driver rebound plate is attached to the support portion <NUM>. The mounting portion <NUM> can have a planar body and include an aperture in the form of a slot <NUM>. The slot <NUM> can have an elongated shape that allows for movement of the mounting member <NUM> in a radial direction with respect to the fastener drive axis <NUM> when the driver impacts the driver rebound plate <NUM>.

The elongated body of the driver rebound plate <NUM> is bent at an angle substantially perpendicular to the direction of the mounting portion to form a retaining portion <NUM>. The retaining portion <NUM> is one of the plurality of intermediate portions in the driver rebound plate. In an embodiment, the retaining portion <NUM> can be bent at a right angle to the mounting portion. The retaining portion <NUM> can be designed to extend in a direction parallel to the drive axis. A center area of the retaining portion <NUM> can be lanced and bent outward to form a retaining tab <NUM>. The retaining tab <NUM> is bent outward in a direction toward the mounting portion <NUM>. The retaining tab <NUM> has a bend portion <NUM> and a free end portion <NUM>. The bend portion <NUM> is proximal to the mounting portion <NUM> and the free end portion <NUM> is proximate to an intermediate impact portion <NUM>.

The impact portion <NUM> of the driver rebound plate <NUM> is adjacent to the retaining portion <NUM> and defines a driver impact region. The impact portion <NUM> is designed to receive an impact from the rear end 16b of the driver <NUM> during a return stroke. The impact portion <NUM> is bent to form a sloping surface with respect to the retaining portion. In the fastening tool <NUM>, the impact portion <NUM> forms an oblique angle with respect to the drive axis <NUM>. In the illustrated embodiment, the impact portion <NUM> includes a single sloping surface that forms an oblique angle with respect to the drive axis <NUM>. In alternative embodiments, the impact portion <NUM> can include a plurality of sloping surfaces in the impact region. The impact potion <NUM> includes an impact face <NUM> and an opposing dampening face <NUM>. The impact face <NUM> receives the impact of the driver <NUM> during the return stroke, while the dampening face <NUM> supports the dampening member <NUM> within the rear housing cover <NUM>. The impact portion <NUM> has a proximal end <NUM> adjacent to the retaining portion <NUM> and a distal end <NUM>.

A distal end <NUM> of the impact portion <NUM> includes a transition portion <NUM> between the impact portion <NUM> and the bearing portion <NUM>. The transition portion defines rest stop <NUM> that is designed to support the rear end 16b of the driver <NUM> when the driver is in the process of returning to the home position. The rest stop is formed substantially parallel to the retaining portion <NUM> and receives the rear end 16b of the driver <NUM> after the driver strikes the impact portion <NUM>. When the driver <NUM> strikes the impact portion <NUM>, the angular or sloping configuration thereof deflects the rear end 16b of the driver out of alignment with the drive axis <NUM>. The continued rearward motion of the driver <NUM> against the sloped impact portion <NUM> forces the rear end 16b of the driver to slide downward or in a direction away from the retaining portion <NUM>, to a position contacting the rest stop <NUM>. The rest stop <NUM> limits the deflection of the driver <NUM> around the driver pivot point <NUM> (<FIG>) to a predetermined amount, such as, for example, the length of the impact portion <NUM>. As a result, the driver <NUM> passes through the impact region, to the transition region rest stop <NUM>. At the rest stop, a rear end face 16d of the driver <NUM>, opposite to the fastener striking face 16c of the driver, is free and not in contact with the driver rebound plate <NUM>, thereby avoiding the need to overcome additional friction during the drive stroke.

Adjacent to the impact portion <NUM> of the driver rebound plate is the second flange or bearing portion <NUM> that bears against the inner surface of the rear housing cover <NUM>. The bearing portion <NUM> secures the non-fastened end of the elongated body within the rear housing cover <NUM>. The bearing portion <NUM> is configured to be located in a plane parallel to the plane of the mounting portion <NUM>. The bearing portion <NUM> includes an aperture <NUM> that provides a clearance for the rear end 16b of the driver <NUM> when the driver is in the impact region. In addition, the aperture <NUM> also provides weight reduction for the driver rebound plate <NUM>.

The slot <NUM> of the mounting portion <NUM> allows the mounting portion to be slidably movable with respect to the drive axis <NUM> upon impact of the driver <NUM> on the impact portion <NUM>. Likewise, the restrained bearing portion <NUM> is also slidably movable with respect to the drive axis upon impact of the driver on the impact portion <NUM>.

In an embodiment, the driver rebound plate <NUM> can be formed from a metal or alloy, such as steel. In another embodiment, the driver rebound plate <NUM> can be formed from heat treated steel. The steel can be heat treated to a hardness value of HRC <NUM>-<NUM>.

<FIG>, <FIG>, <FIG> illustrate that the driver rebound plate <NUM> also supports a pad or dampening member <NUM> that dampens the impact of the driver <NUM> on the housing <NUM> during the return stroke. In particular, the impact portion <NUM> of the driver rebound plate <NUM> not only deflects the driver <NUM> out of alignment with the fastener drive axis <NUM>, but is also adapted to support the dampening member <NUM>. As shown in <FIG> and <FIG>, for example, the dampening member <NUM> is disposed between the driver rebound plate <NUM> and the rearward end surface <NUM> of the rear housing cover <NUM>. In an embodiment, the dampening member <NUM> is supported by the dampening face <NUM> of the impact portion <NUM>. In an embodiment, the free end <NUM> of the retaining tab <NUM> of the retaining portion <NUM> wedges the dampening member <NUM> between the driver rebound plate <NUM> and the rearward end surface <NUM> of the rear housing cover <NUM>.

The dampening member can be formed from an impact absorbing material, such as, for example, a material having a polymer, a rubber, a plastic, a SORBOTHANE®, a synthetic viscoelastic urethane polymer, a synthetic viscoelastic polymer, a polymer, a foam, a memory foam, a gel, a thermoset plastic, PVC, natural rubber, synthetic rubber, closed cell foam, urethanes, resins, multiphase material, reinforced material, or fiber reinforced material. In an embodiment, the dampening member can be made from a rubber-like foam such as CELLASTO®. The dampening member can be attached to the driver rebound plate or located between the driver rebound plate and the interior of the end cap or inner surface of the rear housing cover as shown in <FIG>, to absorb at least a portion of the energy of the driver.

During the return stroke when the driver is moved rearward, the rear end 16b of the driver <NUM> will impact the driver rebound plate <NUM>. The configuration of the driver rebound plate <NUM> interferes, by means of the impact portion <NUM>, with the trajectory of the driver <NUM> and deflects the rear end 16b of the driver. The deflection of the rear end 16b of the driver <NUM> forces the front end 16a of the driver out of alignment with the drive path <NUM> and into abutment with the stop member <NUM>, thereby placing the driver in the home position. By removing the front end 16a of the driver <NUM> from the drive axis <NUM> during the return phase, the front end of the driver is prevented from contacting any portion of the next or second fastener. The stop member <NUM> blocks the driver from moving forward toward the nosepiece and the driver is held in place by the magnet <NUM> until the operator begins the next fastening cycle.

Although a plate is illustrated as a rebound member, any spring-loaded element that can deflect the rear portion of the driver can be serve as a rebound member, including, but not limited to a projecting member. In addition, although the driver rebound plate is illustrated as mounted within the end cap of the fastening tool, the driver rebound plate or rebound member can be located along other portions of the driver path that direct the driver to a stop member to place the driver in the home position.

In an embodiment of the present invention, the fastening tool <NUM> can control rebound of the reciprocating driver by providing the rebound plate <NUM> to deflect or redirect the driver <NUM> toward a stop member <NUM> on or adjacent to the nosepiece <NUM>, and out of the fastener drive path. The stop member <NUM> receives the front end 16a of the driver <NUM> when the driver is in a home position. In the home position, the front end 16a of the driver abuts the stop member <NUM> and can be reversibly magnetically held by the home magnet <NUM> adjacent to the nosepiece <NUM>.

The driver rebound plate <NUM> is provided to receive an impact from the rear end 16b of the driver <NUM> during a return stroke and allow the driver to rebound forward toward the forward end of the housing <NUM>. In particular, the impact portion <NUM> of the rebound plate <NUM> is provided to receive the impact from the driver <NUM>. In an embodiment, the impact portion <NUM> includes a single sloped surface having an impact face <NUM> that forms an oblique angle with respect to the drive axis <NUM>. The driver <NUM> is guided along the drive axis <NUM> to contact the driver rebound plate <NUM>. Arranged between the impact portion <NUM> of the driver rebound plate <NUM> and an inner surface <NUM> of the end cap of the housing or rear housing cover <NUM> is a dampening member <NUM> that absorbs the impact from the driver <NUM>. The impact from the driver <NUM> on the impact portion <NUM> of the driver rebound member <NUM>, deflects the rear end 16b of the driver out of alignment with the drive axis <NUM> during the return stroke; and guides the front end of the driver toward the stop member <NUM>. Abutment of the driver <NUM> with the stop member <NUM> positions the driver in the home position so that the driver is available for the next fastening cycle.

The driver rebound plate can prevent or greatly reduce the number of fastener jams experienced by the operator. Preventing minor or catastrophic jams decreases the wear and failure rates of the fastening tool components. Having fewer jams to clear from the fastening tool will also increase the productivity of the operator operating the tool.

Claim 1:
A fastening tool (<NUM>) comprising:
a housing (<NUM>) having a housing interior, a forward end (12a) , a rearward end (12b), and a support member (<NUM>) disposed in the rearward end;
a drive track (<NUM>) defined within the housing interior;
a driver (<NUM>) reciprocally mounted for movement within the drive track along a drive axis (<NUM>) to drive a fastener during a drive stroke, the driver having a front end (16a) and a rear end (16b);
an elastically deformable member (<NUM>) operatively connected to the support member and bearing against a rearward end surface (<NUM>); and wherein the elastically deformable member is configured to receive an impact from the rear end of the driver during a return stroke; said fastening tool (<NUM>) being characterised in that it further comprises a dampening member (<NUM>) disposed between the elastically deformable member (<NUM>) and the rearward end surface (<NUM>).