EP0254775A1

EP0254775A1 - Manual fastener driving device

Info

Publication number: EP0254775A1
Application number: EP86201345A
Authority: EP
Inventors: Umberto Monacelli
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-07-31
Filing date: 1986-07-31
Publication date: 1988-02-03

Abstract

The device comprises an actuator member (24) subjected to the action of a spring (26), for expelling and driving fastening elements such as staples, nails and the like. One end of a first lever (34) engages the actuator element (24) during its spring-loading stroke. The lever (34) is pivotally mounted on the body of the device and has its other end engaged by a second lever (39) whose point (40) of pivotal mounting on the device is farther away from the actuator member (24) than the point (35) of pivotal mounting of the first lever (34). This makes the device easier to operate. The first lever (34) is provided with a slot (37) in the region of the point (35) of pivotal mounting on the body and its normal rotation during the actuator member loading stage is arrested by a fixed projection (44), after which the lever (34) performs an essentially translatory movement with rapid disengagement of the actuator member (24), which is thus free to expel a fastening element.

Description

There are many manual fastener driving devices now in use to drive staples, pins, nails and the like. Nearly all of this type of device utilizes a channel within the lower portion of the body to hold a quantity of fasteners to be driven. These fasteners are fed toward a fastener slot near the front of the device by a pusher urged forward by a spring.
A driver located perpendicular to the fastener drives the leading fastener from the slot into the workpiece. The driver movement toward the workpiece is usually accomplished by a spring forcing the driver in that direction. To move the driver above the fastener and against the spring force, a lever contacts or hooks onto the driver mounting assembly. As the lever is raised the spring is compressed until the desired position of driver is reached above the fastener. Further movement causes the end of the lever to slip off the driver mounting assembly allowing the spring to move the driver rapidly against the fastener thereby driving the fastener out of the slot.
Many tools have the lever pivoting above a pin with the front edge just under a lip on the driver assembly. As the lever pivots the end raises the driver against the spring resistance. When the driver approaches the correct height above the fastener, the lever pivots away from and out of the way of the vertical path of the driver assembly allowing the driver to be free to drive the fastener.
The disengagement of the lever and the driver assembly is usually done by the end of the lever sliding from under a portion of the driver mount. This sliding motion,with both parts under spring force, creates a wear problem. As the end of the lever wears the release position becomes lower resulting in the spring not being compressed as much, thereby reducing the driving power.
The lifting of the driver assembly, compressing the spring and movement of the engaging surfaces is done in one continuous motion. Using the normal practice of only pivoting the lever for disengagement the dimensions and locating positions must be held close for correct operation therefore increasing manufacturing cost. The present invention solves this problem according to one aspect thereof by providing a large engagement surface during compression of the spring and moving the lever laterally (transversally) away from driver assembly with a simultaneous pivotal movement during disengagement of the parts. This feature will be further clarified in the description and figures of the tool.
Since the spring force is the only power used to drive the fastener it is usually quite strong. This is especially true where the fastener is long and the workpiece is hard. To activate the spring directly is possible, but it would make the tool difficult to operate. To overcome this, a second lever is utlized to react in conjunction with the first to reduce the force needed to apply with the hand of the operator. This is normally accomplished by pivoting the hand operated lever near the front of the tool and extending the free end toward the back of the tool. This will reduce the hand force needed to operate the tool if the lever is made long.
Having the hand operated lever mounted as described above there is a major disadvantage. Since the force is applied away from the driver, the back of the tool must be supported by the workpiece as the lever is pushed downward or by squeezing the lever with the palm of the hand and the fingers wraped around part of the tool. The other hand can also be used to hold the tool against the workpiece in some cases, but in many applications the pieces to be fastened must also be held in position.
If the workpiece to be fastened does not have a surface to support the back of the tool, such as near an overhanging edge of a chair, the operation must be done by a squeezing motion only. This can be tiring if the work must be done continuously for a conside rable time. Being able to apply most of the force needed by pushing downward by the hand rather than continued use of the fingers greatly reduces the fatigue problem.
In application where the workpiece is hard, the area of the fastener opering or slot must be held tightly against the workpiece to keep the tool from raising during the driving cycle. By pushing down on the hand lever this is automatically accomplished, but in applications where the back of the tool is not supported this becomes difficult.
To overcome these problems tools are also made using electric or pneumatic power, but these type tools are generally more costly and in many applications inconvenient due to the length of wire or hose needed to supply the power.
An object of the present invention is to provide an operating means where the hand force can be applied close to the driver position to reduce finger fatigue.
Another object of the present invention is to provide a tool that can be used with one hand and apply force against the workpiece when the back of the tool is unsupported.
Another object of the invention is to provide an operation means that is less sensitive to wear and gives a more consistant drive force.
For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

Figure 1 is a sectional view along a center plane of the tool with the hand lever at rest position,
Figure 2 is a top elevation view,
Figure 3 is a sectional view along a center plane with the hand lever partially depressed.
Figure 4 is a sectional view along a center plane with the hand - 4 lever fully depressed,

Referring to Fig. 1 and Fig. 2 the consist of a guide body 15 in which a rail 16 is located for supporting and guiding fasteners 17. The fasteners shown for convenience are staples but other type fasteners such as pins, brads, nail and the like can also be used depending on the type of application requirement.
The fastener guide rail 16 is positioned at the lower portion of the guide body 15 and is held toward the fastener ejection slot 18 by a releasable latch 19. The latching of the rail 16 within the guide body 15 is shown as a lever mounted on a pin 20 with the lower edge contacting the back portion 21 of the rail 16. The latch 19 is forced in a clockwise direction by a spring 22 causing the rail 16 to be forced toward the front of the tool. This is only one method of the attachment of the rail 16 to the guide body 15 and may differ from that shown and therefore is not a limiting factor on the present invention.
A pusher 23 which cooperates with the rail 16 of the fasteners 17 urges the latter along the rail 16 by a spring (not shown). When the fastener driver 24 is raised, during the operation, above the leading fastener it is moved into the fastener driving slot 18 by the force on the pusher 23. This is also wholly conventional to this type of tool and may vary accordingly.
The driver 24 is sized and shaped according to the type of fastener being utilized and the fastener driving slot 18. To achieve the driver 24 movement, it is attached to a driver mount 25 slidable within the body 15 in a direction parallel to the plane of the fastener driving slot 18. A spring 26 forces the driver mount 25 downward.
To allow for regulation of the driving force a threaded bushing 27 is positioned above the spring 26. Movement of the bushing is controlled by a threaded knob 28. By turning the knob 28 the bushing 27 is displaced decreasing or increasing the space for the spring 28. Decreasing the space makes the spring 26 harder to compress and therefor stores more power for the driving stroke.
One particular way of attaching the knob 28 to the guide body 15 is shown by means of a retaining plate 29 attached securly to the guide body 15. The knob shaft 30 is retained in the plate 29 by a washer 31 and a snap ring 32.
The need for adjustment and means of adjusting will vary depending on style of device used and in some cases no adjustment is necessary therefore the spring force is fixed and the bushing 27, knob 28 etc. are no installed.
Since the spring force could be large and the resistance of the workpiece to the driving of the fastener low, the lower portion of the guide body 15 would receive a hard blow at end of each stroke, to protect the body 15 from damage a shock absorber 33 is positioned at the bottom of the guideway of the driver mount 25.
To raise the driver mount 25 against the resistance of the spring 26 a first lever 34 is pivotally mounted on the guide body 15. A pin 35 and a bearing 36 passes through a slot 37 in the lever 34. The front edge 38 of the lever 34 is positioned under a protecting portion of the driver mount 25. As the lever 34 pivots clockwise about pin 35 the front edge 38 engages and raises the driver mount 25.
In most cases the force of the spring 26 is great and the lever will require a considerable counter force to achieve rotation. To reduce the manual force needed to move lever 34 a second hand actuated lever 39 is mounted on the body 15 pivotal about pin 40. A rollder 41 is made as part of lever 39 to reduce friction on lever 34.
By mounting the pivot 40 of lever 39 further away from the driver mount 25 than the pivot 35 of lever 34 the rotation of lever 39 is in a counterclockwise direction as shown in Fig. 1. By mounting of the lever pivots as shown provides for the hand force to cycle the device to be near the front of the tool. The positioning of the force according to this invention allows the tool to be actuated by a downward force with out support of the back of the device on the workpiece.
A cavity 42 in the guidebody 15 is provided to place the fingers for carring the tool. The cavity 42 also allows the fingers to be wraped around part of the guide body 15 to operate the tool as by a squeezing motion.
Referring now to Fig. 3 the hand lever 39 is shown partially depressed. Roller 41 has caused rotation of lever 34 about pin 35 lifting driver mount 25. A protecting lower portion 43 of lever 34 has contacted a part of fixed portion 44 of the guide body 15 stopping rotation of lever 34. A pin 44 is shown although any other type stop could be utilized.
Referring now to Fig. 4 the hand lever 39 has been fully depressed. Since the stop pin 44 restricts the rotation of lever 34, the further movement of lever 34, caused by downward force of roller 41, moves lever 34 in a lateral direction, i.e. perpendicularly to the direction of movement of the driver element 24, away from driver mount 25.
There could also be some rotation movements. As the end 38 withdraws from under the driver mount 25 the mount 25 is free to move downwards driving the leading fastener 17 into the workpiece.

Claims

1. A manual fastener driving device comprising a guide body having a fastener slot from which the fasteners are driven into a workpiece, a driver member slidable in said guide body, a resilient means forcing said driver member toward said fastener slot, an operating means to first move said driver member away from said fastener slot against resistance of said resilient means and then disengage said driver member allowing said driver member to move toward said fastener slot, characterized in that said operating means comprise a first lever pivotally mounted on said guide body with one end engaging said driver member and an opposite end engaged by a hand actuatable second lever; said second lever being pivotally mounted on said guide body, at a point spaced from said driver member more than the pivot point of said first lever, pivotal movement of said second lever causing opposite pivotal movement of said first lever.

2. A device according to claim 1, characterized in that said first lever contacts a fixed portion of said guide body during part of its movement, said fixed portion stopping normal rotation of said first lever and causing displacement of said first lever in a more lateral direction away from said driver member, said displacement causing disengagement between said first lever and said driver member.

3. A device according to claim 2 characterized in that said first lever has a slot to allow said lateral movement of said first lever.