GB2117692A - Latching arrangement for a power-driven tacker - Google Patents

Abstract

A power-driven tacker has a body (10) having a lower compartment (16) at least partly housing a magazine assembly (18) and containing a switch (92, Fig. 5, n.s.) for actuating solenoid driving means (30, 32). An elongated linkage member (54) is connected at its upper end to an actuating trigger (28) for movement thereby, the linkage (54) extending downwardly through the body (10) into the lower compartment (16), and has one part (62) of a latch mechanism at its lower end. A latch member (68) comprises the other part of the latch mechanism and is moveably mounted in the lower compartment (16) and engages the latch part (62) to normally render the trigger (28) inoperative, upward pivotal movement of the magazine assembly (18) moving the latch member (68) out of engagement with the latch pat (62) to render the trigger operative. A cam (120, Fig. 4, n.s.) on the lower end of the linkage member (54) actuates the switch (92) upon movement of the linkage member (54) by operation of the trigger (28). <IMAGE>

Description

SPECIFICATION Latching arrangement for a power-driven tacker FIELD OF THE INVENTION This invention relates to power-driven tackers for driving or firing fasteners, such as staples or tacks, into a work piece. It particularly relates to electrically-powered tackers such as electrically actuated fastener driving tools.

BACKGROUND OF THE INVENTION Power-driven tackers for driving fasteners such as staples, brads and the like are well known. It is usual in electrically-powered tackers to employ a solenoid winding for accelerating an armature to drive or fire the fasteners at high speed into the work piece. These power-driven tackers are actuated by a triggerswitch arrangement in the handle thereof.

However, should the trigger accidentally be actuated and a fastener be fired when the power-driven tacker is not in engagement with the work piece, then injury could occur to the operator or any person nearby.

It has been proposed in German Auslegeschrift No. 1,286,469 with power-driven tackers operated by compressed air, to arrange for an operating lever to be blocked against actuation by a hooked end thereof engaging a plate extending vertically upwardly from the pivoted fastener magazine assembly. Upon placing the tool on a work piece and pushing downwardly to pivot the magazine assembly towards the body of the tool, the blocking plate moves upwardly to a position in which an aperture therein registers with the previously blocked end of the operating lever to allow actuation thereof, the lever's hooked end being able to pass through the aperture.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved power-driven tacker with electric driving means and having an improved safety mechanism.

It is a further object of the invention to provide a latching mechanism, for rendering the actuating trigger inoperative, completely within the confines of the body of the poweroperated tacker.

Yet another object of the invention is to provide a power-driven tacker with a lower body compartment housing the switch for energizing the tacker.

According to the present invention there is provided a power-driven tacker having a body with a handle portion, a magazine assembly for fasteners pivotally attached to the body, means for driving the fasteners into a work piece, a manually operated trigger associated with the handle portion for actuating the driving means, and an arrangement for rendering the trigger inoperative until the magazine assembly has been pivoted upwardly by an operator pressing the tacker downwardly on a work piece, characterized in that: the body has a lower compartment at least partly housing the magazine assembly and containing a switch for actuating electric driving means; an elongated member connected at its upper end to the trigger for movement thereby, the elongated member extending downwardly through the body into the lower compartment, and having adjacent its lower end latch means; a latch member movably mounted in the lower compartment and engaging the latch means to normally render the trigger inoperative, upward pivotal movement of the magazine assembly moving the latch member out of engagment with the latch means to render the trigger operative; and means, associated with the elongated member, for actuating the switch upon movement of the elongated member by manual operation of the trigger.

Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Figure 1 is an elevational view of a powerdriven tacker according to the invention; Figure 2 is a diagrammatic elevational view, on a larger scale, with part of the housing broken away and some of the components shown in vertical section, of the power-driven tacker of Fig. 1 in the inoperative position; Figure 3 is a similar view to Fig. 2 but in the operative position having just fired a fastener and with some parts omitted for clarity; Figure 4 is a diagrammatic fragmentary section on part of the line 4-4 in Fig. 3; Figure 5 is a similar view to Fig. 4 but taken on part of the line 5-5 in Fig. 2; and Figure 6 is a view on the section line 6-6 in Fig. 3 of the lower part of the elongated member for actuating the switch.

DETAILED DESCRIPTION OF THE PRE FERRED EMBODIMENT The preferred embodiment of the present invention is illustrated by way of example in Figs. 1 through 6.

Fig. 1 shows the power-driven tacker 8 having a body 10 with a handle portion 1 2 depending rearwardly from the upper portion of the body 10. A power lead 14 for supplying line voltage to the tacker 8 extends rearwardly from the rear end of the handle 12.

The body 10 has a lower compartment 1 6 in which a magazine assembly 1 8 is pivotally attached at 20 adjacent to the rear thereof.

The forward end of the magazine 1 8 has a downwardly projecting nose 22 through which fasteners are driven into a workpiece. A control dial 24 is mounted on an upper surface 26 of the lower compartments 1 6 for selecting different settings for the tacker 8. An elongated trigger 28 for actuating the tacker 8 is mounted on the underside of the handle 1 2 with its forward end extending into the body 10 and its rear end pivoted internally in the handle 1 2 adjacent the rear end thereof.

Fig. 2 shows diagrammatically an annular solenoid coil unit 30 vertically mounted in the body 10 with its lower portion extending into the lower compartment 1 6. A cylindrical, iron armature 32, having an axial central bore 34 therethrough, is slidably mounted by means of two sleeve bearings 35 on a guide rod 36 extending axially through the center of the solenoid 30. The rod 36 is securely mounted at its upper end in the top of the body 10 and at its lower end in the lower compartment 16.

The armature has secured to the upper end thereof a collar 38. A coil spring 40 is under compression between the upper end of the solenoid 30 and the underside of the collar 38 to urge the armature 32 upwardly to its normal upper position shown in Fig. 2. The collar 38 extends in cantilever manner to the right of the armature and is drivingly connected to the upper end of a flat, elongated driving blade 42, only the lower portion of which can be seen in Fig. 2. The magazine assembly 1 8 has an upwardly extending bracket at its rear end which is pivoted on the screw 20. The magazine 1 8 is adapted to slidably house a stack of fasteners (not shown), for example generally U-shaped staples or tacks having an upper connecting part and two downwardly extending legs as is well known, and spring feed these towards the nose 22.Upon energization of the solenoid 30, the armature causes the driving blade 42 to be sharply accelerated and driven downwardly so that the lower end of the driving blade 42 engages and passes through the nose 22, at the same time driving the forward most fastener of the stack through the nose into a work piece. For a fuller understanding of the general construction and operation of a power-driven tacker see United Kingdom Patent Application 2,024,691, published January 16, 1980, and United States Patent 4,005,812, the disclosures of both of which are hereby incorporated by reference.

Continuing-with Fig. 2, the elongated trigger 28 is of channel-like construction, open along it upper side, and pivotal connection thereof to the handle 1 2 is shown in phatom at 44. Intermediate its length, an upward hollow cylindrical projection 46 has engaged thereover a coil spring 48 the upper end of which engages a socket 50 in the handle 1 2 to resiliently urge the trigger 28 into the lower position shown. The trigger 28 has a downwardly turned, open, forward end 52 located in the housing 10. A downwardly extending, elongated member 54 has a transverse pin 56 integrally formed at its upper extremity which pivotally engages in the slide walls of the trigger 28 adjacent the forward end 52 thereof.The elongated member 54 extends into the lower compartment 1 6 and has at the lower end, on the right in Fig. 2, an integrally formed guide projection 58 which slides downwardly and upwardly against an internal wall 60 of the lower compartment 16. Immediately above the guide projection 58, but on the opposite side thereto, the elongated member 54 is formed with a small rearwardly extending tooth 62 of triangular vertical crosssection. The tooth 62 is shown engaging a slot 64 in an upwardly extending first leg 66 of a latch member 68. The latch member 68 has a second leg 70 extending downwardly and forwardly, the end thereof contacting the upper surface 72 of the magazine assembly 18. This second leg 70 subtends and internal angle of approximately 1 30 degrees with the first leg 66.At the junction of the first and second legs, 66 and 70, a transversely extending pivot pin is integrally formed, shown in phantom at 72, and which is pivotally mounted in brackets 74 extending upwardly from the bottom wall 75 of the lower compartment 16.

A third leg 76 extends rearwardly and downwardly from the first leg 66 at a location above the pivot 72. This third leg substends an internal amgle of approximately 1 20 degrees with the first leg 66. The lower end of the third leg 76 engages an upper surface portion 78 of the bottom wall 75.

In the position shown in Fig. 2, the slot 64 of the first leg 66 engages the tooth 62 on the elongated member 54 to pevent upward actuating movement of the trigger 28, and retains the trigger 28 in a lower inoperable position. The first leg 66 is retained in this position by the third leg 76 being flexed against the surface 78 to resiliently urge the latch member 68 clockwise in Fig. 2. This arrangement also causes the second leg 70 to urge the magazine assembly 1 8 downwardly to its lower position shown in Fig. 2.

A printed-circuit board 80 is mounted in the lower compartment 16, and includes circuitry and components for operating the solenoid 30. One such component 82, connected for rotational adjustment by the dial 24, can be seen in Fig. 2. The printed-circuit board 80 has a cut-out portion 84 to accommodate the lower end of the elongated member 54 and the first leg 66.

Fig. 3 shows the relative position of the parts just after the tracker 8 has been energized to fire a fastener or tack (not shown) into a work piece (not shown). Before firing the fastener, the tacker is placed on the workpiece and pressed downwardly. This causes the nose 22 to move upwardly and pivot the magazine assembly 18 some degrees anti-clockwise in Fig. 3. Contact of the second leg 70 on the upper surface 72 of the magazine 1 8 causes the latch member 68 to rotate anti-clockwise, to the position shown in Fig. 3, so disengaging the slot 64 from the tooth 62, thus rendering the trigger 28 operative. The trigger 28 can now be manually squeezed to move the elongated member 54 upwardly to actuate the solenoid 30, as will be described below in relation to Figs. 4, 5 and 6.Upon such actuation, the armature 32 is accelerated to its lower position, shown in Fig. 3, moving with it the driving blade 42; as can be seen, the driving blade is thrust through a guide slot in the magazine and completely penertrates the nose 22. At the completion of this firing stroke, the end of the driving blade 42 penetrates just beyond the nose 22, as can be seen in Fig. 3. As soon as the trigger 28 is released, the spring 48 returns both the trigger 28 and the elongated member 54 downwardly to the position shown in Fig. 2.As soon as the tacker 8 is lifted from the work piece, either deliberately or as a consequence of recoil action upon firing, the flexed third leg 76 will rotate the latch member 68 clockwise aiding the downward pivotal movement of the magazine assembly 18, and causing the slot 64 in the first leg 66 to re-engage the tooth 62 and render the tacker inoperative.

An upwardly extending extention bracket 86 of the magazine assembly 1 8 can be seen on the right in Fig. 3, the bracket 86 having an upwardly extending slot 88 which engages a pin 90 in the lower compartment 1 6 to limit both the upward and downward pivoting movement of the magazine assembly 1 8.

Fig. 5 shows a switch 92 mounted on the printed-circuit board 80 and disposed in the lower compartment 1 6 for energizing the solenoid upon actuation of the trigger 28 (Fig. 2).

The switch 92, shown in the open position in Fig. 5, has a fixed metal contact 94 mounted on the printed-circuit board 80 and upstanding therefrom and a movable contact 96 mounted on the free end of a copper arm 98 pivoted at its other end 100 to a fixed, somewhat Z-shaped metal bracket 102. The Z-shaped bracket 102 is mounted on and is upstanding from the printed-circuit board 80.

A larger, generally L-shaped arm 104 of insulating plastics material is pivoted at one end 106 to a short leg 108 of the fixed bracket 102. A coil spring 110, under tension, is attached at one end 11 2 to a leg of the Lshaped 104, and at the other end 114 to the pivoted arm 98 intermediate the length thereof. A heel portion 11 6 projects from the apex of the L-shaped arm 104 and cooperates with the lower end of the elongated member 54, as will be described below. A spring 118, attached at its ends to and under compression between the fixed bracket 102 and the pivoted L-shaped arm 104, resiliently urges the heel 11 6 into engagement with the elongate member 54.

The relative positions of the parts in Fig. 5 corresponds to the position shown in Fig. 2 when the tacker 8 is in the inoperative position. As can be seen in Fig. 5, (although somewhat distorted out of the sectional plane 5-5 of Fig. 2), the first leg 66 of the latch member is in abutment with the elongated member 54 with the tooth 62 of the latter engaged in the slot in the first leg 66.

Fig. 4 shows the switch in the closed position and corresponds to the operative and actuated position of the tacker shown in Fig.

3. The first leg 66 has been moved away from the elongated member 54, disengaging the latter from the tooth 62. The elongated member 54 has been moved upwardly and a cam 120, extending from one side at the bottom thereof, has acted upon the heel 11 6 of the L-shaped arm 104 causing the latter to pivot counter-clockwise from the position shown in Fig. 5 to that in Fig. 4. The pivoted L-shaped arm 104, the pivoted arm 98, the spring 110, and the fixed bracket 102 are arranged so that pivoting of the L-shaped bracket 104 creates a toggle action on the pivoted arm 98. Thus, the arm 98 pivots clockwise (in Fig. 4) under the toggle-action influence of the spring 110 to close the contacts 96 and 94.

Fig. 6 shows the triangular shaped cam 1 20 extending sideways from the bottom of the elongated member 54. The tooth 62 can also been seen.

The operation of the power-driven tacker will now be briefly summarized.

The handle 1 2 is grasped in one hand by an operator. While the tacker 8 is out of contact with a work piece, the magazine 1 8 is in its lower position and the latch member 68 engages the latch means of the elongated member 54, i.e. the tooth 62, to prevent actuation of the trigger 28 so rendering the tacker 8 inoperative. When the nose 22 is pushed against a work piece to pivot the magazine 1 8 inwardly of the lower compartment 16, the latch member 68 is rotated anticlockwise out of engagement with the elongated member 54 so that the latter is now free to move upwardly and the trigger 28 can be actuated.Thereafter, actuation of the trigger 28, by the operator squeezing it into the handle 12, lifts the elongated member 54 causing the cam 1 20 thereof to close the toggle switch 92 and, through the printedcircuit board 80, energize the solenoid 30 to cause the driving blade 42 to fire a fastener from the magazine 18, out of the nose 22 into the work piece. Upon release of the trigger 28 and pivoting of the magazine to its lower, outward position, the latch member, under the influence of the flexed third leg 76, re-engages the elongated member 54 to render again the trigger 28 inoperative. At the same time, the downward movement of the elongated member 54 enables the spring 11 8 to move the heel 11 6 over the cam 1 20 and open the switch 92.

It will be appreciated that the elongated member performs two functions, namely, being part of the latching mechanism for rendering the trigger inoperative, and actuating the operation switch. This enables the operating switch to be housed in the lower compartment of the tacker body, and further enables the latching mechanism to be totally confined within the body of the tacker.

By having the body of the tacker formed with an enlarged lower compartment, the tacker has improved stability when placed upon the work piece and can be readily manipulated by the operator.

The above described embodiment, of course, is not to be construed as limiting the breadth of the present invention, modifications, and other alternative constructions, will be apparent which are within the spirit and scope of the invention as defined in the appended Claims.

For example, the latch means of the elongated member could be a slot and the pivoted latch member could be provided with a tooth or projection for engaging therein.

Claims (11)

1. A power-driven tacker having a body (10) with a handle portion (12), a magazine assembly (18) for fasteners pivotally attached to the body (10), means (30) for driving the fasteners into a work piece, a manually operated trigger (28) associated with the handle (12) for actuating the driving means (30), and an arrangement for rendering the trigger inoperative until the magazine assembly (18) has been pivoted upwardly by an opperator presssing the tacker downwardly on the work piece, characterized in that:: the body (10) has a lower compartment (16) at least partly housing the magazine assembly (18) and containing a switch (92) for actuating electric driving means (30); an elongated member (54) connected at its upper end to the trigger (28) for movement thereby, the elongated member (54) extending downwardly through the body (10) into the lower compartment (16), and having adjacent its lower end latch means (62); a latch member (68) movably mounted in the lower compartment (16) and engaging the latch means (62) to normally render the trigger (28) inoperative, upward pivotal movement of the magazine assembly (18) moving the latch member (68) out of engagement with the latch means (62) to render the trigger operative; and means, associated with the elongated member (54), for actuating the switch (92) upon movement of the elongated member (54) by manual operation of the trigger (28).

2. The power-driven tacker of Claim 1, characterized in that the switch (92) is mounted on a printed-circuit board (80) for controlling operation of a solenoid (30) arranged to drive the fasteners into the work piece.

3. The power-driven tacker of Claim 1 or 2, characterized in that the latch member (68) is resiliently biased towards engagement of the latch means (62).

4. The power-driven tacker of Claim 3, characterized in that the latch member (68) is pivotally mounted in the body (10) and has a first leg (66) for engagement with the latch means (62) and a second leg (70) in engagement with the magazine assembly (18).

5. The power-driven tacker of Claim 4, characterized in that the latch member (68) has a third leg (76) engaging the body (10) and flexed to resiliently bias the latch member (68) towards engagement of the latch means (62).

6. The power-driven tacker of Claim 4 or 5, characterized in that the latch means (62) comprises a tooth (62) on the elongated member (54) engageable with a slot in the first leg (66) of the latch member (68).

7. The power-driven tacker of any one of the the preceeding claims, characterized in that the elongated member (54) is pivotally connected to the trigger (28).

8. The power-driven tacker of any one of the preceeding claims, characterized in that the switch actuating means (120) comprises a cam (120) projecting laterally from the elongated member (54).

9. A power-driven tacker having a body (10) with a handle portion (12), a magazine assembly (18) for fasteners pivotally attached to the body (10), means (30) for driving the fasteners into a work piece, a manually operated trigger (28) associated with the handle (12) for actuating the driving means (30), and an arrangement for rendering the trigger inoperative until the magazine assembly (18) has been pivoted upwardly by an operator pressing the tacker downwardly on the work piece, characterized in that:: the body (10) has a lower compartment (16) and the handle (12) extends rearwardly from the upper part of the body with solenoid driving means (30, 32) housed in the body (10) and extending from adjacent the handle (12) downwardly into the lower compartment (16); a switch (92), mounted on a printed-circuit board (80), disposed in the lower compartment (1 6) for energizing the solenoid driving means (30, 32); linkage means (54) connected to the trigger (28) and extending downwardly into the lower compartment (16) for actuating the switch (92); ; a latching member (68) disposed in the lower compartment (16) and coacting with the linkage means (54) and the magazine assem bly (18) to normally engage the linkage means and render the trigger (28) inoperative, and being moved out of engagement with the linkage means (54) by upward movement of the magazine assembly.

10 The power-driven tacker of Claim 9, characterized in that the latching member (68) is pivotally mounted, has a first part (66) for engaging and latching with the linkage means (54), a second part (70) engaging the magazine assembly (18), and resilient means biasing the first part (66) towards engagement with the linkage means (54).

11. A power-driven tacker substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.