Power Driven Hammer

Abstract

An automatic nailing machine having a vertically reciprocable hammer normally urged downwardly, liftable by a motor-driven pinion twice each revolution of the pinion, normally latched in its upright cocked position but releasable by the pinion when a hand-operated trigger is actuated, for intermittent or repeated hammering operations. The hammer head is removable from the hammer slide.

Description

BACKGROUND OF THE INVENTION

Heretofore power driven hammers have been provided wherein the hammer is retracted by a motor and means are provided to de-energize the motor after a hammer movement to prevent repeated movement.

In the present device, the cycle provides for continuous repeating operation at will or intermittent operation at will, and in both cases the control is mechanical without requiring starting and stopping of the electric motor drive. While this concept is broadly shown in prior art, in the present arrangement, the manually operated trigger only releases the trip mechanism so that it can be operated by the pinion. By this construction, there can be no manual release of the hammer that permits it to descend by the spring and crash against the gearing. Also there can be no hazardous accidental release of the hammer if its motor has been turned off and it has been set aside in cocked position.

The present hammer also can be built for heavy duty, driving of nails, spikes, or the like, although many of its features can be employed in light-duty work as for staples. The hammer itself is firmly supported for sliding movement by being mounted on a slide that surrounds a vertical column. Manually operated latch means is constructed to minimize problems of wear and can be adjusted to take up wear should it occur. The hammer element itself can be replaced.

In the drawings:

FIG. 1 is an elevation of the hammer with one side panel removed and with some parts shown in section;

FIG. 2 is an enlarged section taken on the line 2--2 of FIG. 1;

FIG. 3 is a bottom view with the bottom panel removed;

FIG. 4 is an end view from the right end of FIG. 1 with the end panel removed and other parts shown in section;

FIG. 5 is a vertical section through the latch mechanism taken on the line 5--5 of FIG. 1;

FIG. 6 is another vertical section through the latch mechanism taken on the line 6--6 of FIG. 1;

FIG. 7 is a third vertical section through the latch mechanism taken on the line 7--7 of FIG. 1; and

FIG. 8 is an enlarged elevation of the latch mechanism.

The hammer may be constructed with a casing 10 here shown as being a box-like construction. It has panels that are removable to give access to the interior, and are held in place by screws (not shown) or like attachment devices. Externally the housing also has a carrying handle 11.

Power is supplied by a motor 12 mounted on a U-bracket 13 secured as by welding to the back wall 14 of the housing 10. A medial partition wall 15 extends across the interior of the housing adjacent one end of the motor 12. The worm shaft 17 is mounted in bearings in the partition 15 and an end wall 18 of the housing 10. A belt and pulley arrangement 19 connects the motor 12 to the shaft 17 for operation of the shaft by the motor. The shaft 17 extends outside the housing through the wall 18 and has a knob 20 on its outer end which enables it to be turned manually.

The shaft 17 drives a worm wheel 21 that meshes with a pinion 22 that is mounted on a cross shaft 23 having bearings in the front wall 25 and the rear wall 14 of the housing 10. There is a switch 26 constituting a master control for the motor, and hence for the hammer. Thus operation of the motor 12 through the belt and pulley 19 drives the shaft 17, the worm gear 21, and the pinion 22.

The front face of the pinion 22 has two arcuate racks or gear segments 28 projecting from its forward face, as shown. Each of these arcuate racks in turn can engage a linear rack 30 that is part of the hammer subassembly generally indicated at 31.

This hammer subassembly includes a strong, approximately square column 36 welded or otherwise secured to the top panel 37 and to the bottom panel 38 of the housing. The column 36 is shown as having flanges at its bottom and top that are bolted to the wall panels (see FIG. 2).

A hammer slide 42 has a free sliding movement vertically on the column 36. The slide 42 is likewise non-circular so that it will not twist on the column, and is here shown as being approximately square in cross section. The back wall 43 of the hammer slide projects outwardly a short distance at one edge (FIG. 2) and has the linear rack 30 on it in position to mesh with either of the two arcuate racks 28, that project from the face of the pinion 22. The front wall 45 of the hammer slide projects out at the opposite edge whereto a removable hammer 46 is attached by screws 47. This hammer has a depending head 48 that is located above the end of a conventional nail magazine diagrammatically illustrated at 49. As is known in the art, the nails N are fed to the right in FIG. 2 by a spring mechanism 50 so that there is a nail to be driven in position under the hammer head 48. Noting FIGS. 2, 3 and 4, the magazine 49 holds the headed nails N on a slotted track, the nails being urged one at a time to the position under the head 48 by the spring and presser assembly 50. This mechanism can be like that in a conventional stapler.

The hammer head 48 is removable because it constitutes a wear member. This is accomplished by removing the screws 47.

Removing the screws 47 removes the hammer 46 of which the hammer head 48 is a part, so that removal of the screws ultimately results in removal of the hammer head.

A coil spring 52 is a tension spring that draws the hammer slide 42 downwardly sharply. The spring 52 is anchored at its lower end by a clip assembly 53 and at its upper end it is held by a pin 54 that spans and is secured to the upper end of the slide 42. To accommodate the pin during descent of the slide 42, the column 36 has opposite slots 56.

A releasable latch means is provided to hold the hammer in its cocked position but to prevent it from moving to the nail-driving position. The upper end of the linear rack 30 has a projecting tooth, or latching lug, 60. This lug 60 should be displaced forwardly (in FIG. 1) from the rack 30 so as not to interfere with the racks 28. This is illustrated in FIG. 4. Adjacent this lug 60 in its upper position there is a bracket 61 attached to the top wall 37 and depending therefrom. The bracket 61 supports a sliding latch bar 62, the end of which can project under the latching tooth 60. These members are sloping so that as the slide 42 comes up, the upper sloping surface of the tooth 60 will engage the lower sloping surface of the slide bar 62, and displace the bar leftward in FIG. 1 out of the way of the tooth so that the tooth can move to a position above the slide bar. The slide bar 62 is normally urged to the right yieldingly by a coil spring 63 acting between the partition 15 and a collar 64 that is fixed to the bar 62. As shown in FIG. 8, the collar 64 can be adjusted on the bar 62 and then fixed with a set screw. With the parts thus far described, the hammer 42 is lifted, latched and held in its upright position each time the pinion 22 makes half a revolution. The gap between the arcuate racks 28 gives time for a nailing descent of the hammer.

A trigger means is provided to enable the pinion to release the hammer, whenever a hammer action is desired. A long lever 67 is pivoted at 68 to the side of the bracket 61. It depends to one side of the bar 62 and down adjacent one face of the pinion 22, but above the arcuate racks 28. This lever is normally urged to the right in FIGS. 1 and 8 by a coil spring 70 that extends between the lever 67 and the bracket 61. The lever 67 may engage a pin 72 attached to the rod 62 to limit the amount of counterclockwise rotation of the lever 67.

The lever 67 normally can swing freely to the left from the position indicated in FIGS. 1 and 8, in the sense that such movement is not obstructed by a stop, to be described. It depends at its lower end into the path of cams 75 that project outwardly from the face of the pinion 22. Either of these cams can engage the depending end of the arm 67 and swing the arm about its pivot 68 in a clockwise direction in FIGS. 1 and 8. If the trigger mechanism to be described is in the normal untriggered position, this swinging will not move the bar 62 or remove its end from beneath the tooth 60. As rotation of the pinion 22 proceeds, the cam swings out from under the tapered end of the arm 67, whereupon the spring 70 will cause the arm to move back counterclockwise until stopped by the pin 72 projecting from the rod 62.

Manually controlled means are provided to cause the hammer to be driven down by its spring 52. Adjacent the upper end of the handle 11 on the top of the housing 10, there is a trigger 80 pivoted to the handle at 81 for rocking movement. A rod 82 is pivotally attached to the trigger 80 and depends through an opening in the top wall 37 to engage and be pivoted in a stop link 83. A coil spring 84 acts between the undersurface of the top wall 37 and an appropriate washer 85, to urge the link 82 downwardly. The stop link 83 is swivelled at 86 to the collar 64 that is attached to the rod 62. Thus when the trigger 80 is squeezed by the hand engaging the handle 11, and its end is pulled upwardly, the link 82 is pulled upwardly and the stop link 83 swivelled clockwise about the pivot 86 until its right-hand end is within the path of the long arm 67, as shown in dashed lines in the drawing. The engagement of the lower end of the lever 67 by one of the cams 75 rocks that lever clockwise. Since that lever is then in engagement with the stop link 83, it pushes on the end of the stop link, thereby pushing the collar 64 that in turn is secured to the rod 62, moving the rod 62 to the left against the spring 63 and withdrawing its right end from the tooth 60. When this occurs, the hammer is forcefully drawn downwardly by the spring 52 and drives the nail.

OVERALL OPERATION

As it is understood in the art, the magazine 49 is duly filled with nails, spikes or the like which disposes one in the path of the hammer 48, and will move an additional one into place as soon as the first one is driven and the hammer is withdrawn. The nailing machine is duly connected to a source of electric power and the switch 26 operated to energize the motor. When this occurs, the pulley and belt arrangement 19 will drive the shaft 17 and through the worm gear 21 will rotate the pinion 22. Assuming the hammer to have been at its lower position, the rotation of the pinion 22 will cause one of the arcuate racks 28 to engage the linear rack 30 and move it upwardly, the pinion 22 moving counterclockwise in FIG. 1. At the upper end of its movement, the hammer 42 will bring the tooth 60 into engagement with the sloping end of the bar 62 displacing the bar 62 away until the tooth 60 has moved to above the bar, whereupon the spring 63 will force the bar to the right again under the tooth 60 to hold the hammer in its upper position where it is cocked for a hammering operation.

If the operator has not at this time squeezed the trigger 80 upwardly, the stop link 83 will be in the position of FIG. 8 rather than in the position of FIG. 1. Shortly after the arcuate cam 28 has moved beyond the position where it lifts the hammer 42, the cam 75 on the face of the pinion 22 will engage the lower end of the long link 67 and rock that link clockwise about its pivot 68. With the top link 83 in its upper position of FIG. 8, the long lever 67 merely rocks about the pivot without performing any work, until the cam 75 moves from under the bottom of the lever 67 permitting the spring 70 to return that lever to its position against the pin 72. Continued rotation of the pinion 22 will merely repeat the rocking of the lever 67 but no hammering action will occur.

In order to have a hammering action, the user squeezes the trigger 80 upwardly. This draws on the rod 82 and rocks the stop link 83 down to the dashed line position of FIG. 8 and the full line position of FIG. 1. This is an enabling action which conditions the latch mechanism for release, but does not actually perform the release. Only when the pinion 22 revolves to a position wherein a cam 75 can engage the lower end of the long lever 67 does the release take place. When this happens, the cam 75 moves the lower end of the lever 67, which now pushes leftward on the end of the stop link 83 that is pivotally connected at 86 to the collar 64 attached to the latch rod 62, which is thus moved to release the tooth 60 on the hammer 42. The hammer then rapidly descends under the action of the spring 52, causing a nail to be driven.

As soon as the cam 75 passes beyond the end of the lever 67, that lever is again released. If the trigger 80 is held squeezed, the spring 63, acting through the pivot 86 and the stop link 83 pushes the rod 62 back to the position for future latching. If the trigger 80 is released, however, so that the stop link 83 can move to its full line position in FIG. 8, nevertheless, the rod 62 is moved back by the spring 63 and the lever 67 is moved back by the spring 70 to the latching position.

If the trigger 80 is held squeezed through repeated revolutions of the pinion 22, there will be repeated nailing, with two nails being driven for each rotation of the pinion. In this case, the stop link 83 simply stays down in position to be engaged by the lever 67.

If wear occurs in the trigger mechanism parts 67 and 83, the collar 64 can be repositioned on the rod 62 to accommodate such wear. Also the hammer element 46 can be removed by removing the screws 47 and another hammer installed in the event the hammer is damaged or worn.

The advantages of the present construction include the mechanism by which the trigger operation only conditions the mechanism for release of the hammer, the release to be effected by one of the cams 75. If the trigger 80, whenever operated to a release position, permitted the hammer to go down, the descent could occur while one of the arcuate racks 28 is in a half-way position, causing the hammer to strike the rack with severe force and perhaps damage the teeth. Of greater importance is the safety factor. If the trigger is released at a time when the motor 12 is not running, there is practically no possibility of having the hammer released to drive a nail. It will be recognized that if, for example, the apparatus is set to one side in a cocked condition, it would be a serious hazard if a release of the trigger could cause the driving of a nail. A person might set the apparatus down on a finished surface or even near or on a human being whereupon the driving of the nail would have serious consequences.

It is also notable that the present equipment is compact, but can be used for heavy-duty nailing. Having the arcuate gears and cams on the pinion face saves space and having the trigger mechanism in the same general area likewise saves space. The use of the strong column 36 of an uncircular nature, especially a square shape in cross section, and a similar shape to the nail slide itself provides a very strong structure.

Various changes and modifications may be made within this invention as will be readily apparent to those skilled in the art. Such changes and modifications are within the scope and teaching of this invention as defined by the claims appended hereto.

Claims

What is claimed is:

1. In a power hammer: a rotary driving element; a base support; a hammer member slidably mounted on the support for movements from a cocked position in a driving direction; spring means to move the hammer member in the driving direction; releasable latch means on the support and engageable with the hammer member to hold the hammer member in cocked position against the spring means; and latch release means on the support to move the latch means to release position, the latch release means including means driven by the driving element, and manually operable means to connect or disconnect the means driven by the driving element to the latch means to cause the driving element to move the latch means to release position.

2. In the hammer of claim 1: the manually operable means including a trigger, a stop link movable by movement of the trigger to a first position between the means driven by the driving element and the latch means to drivingly connect them, and to a second position that does not connect them, whereby the driving element can be connected or disconnected from the latch means depending upon the position of the trigger.

3. In the hammer of claim 2: the driving element including a pinion gear having a driving connection to the hammer member, the means driven by the driving element including a rocking link extending adjacent the pinion, and cam means on the pinion engageable with the link to displace the link upon rotation of the pinion, the stop link being engageable by the rocking link.

4. In the hammer of claim 3, the stop link being supported on the latch means, and movable therewith.

5. In the hammer of claim 4, the latch means comprising a slide bar and yieldable means urging the bar into latching position.

6. In the hammer of claim 1: the driving element comprising a pinion having a gear-tooth arrangement for moving the hammer in one direction, in the form of two angularly spaced arcuate gear sets beside the face of the pinion and connected for rotation with it, and a rack on the hammer member engageable by each gear set for lifting the hammer member against the spring means; and the latch release means including a member depending alongside the face of the pinion, and cam means associated with each gear set for displacing the depending member at the end of each elevation of the hammer by such gear set.

7. In the hammer of claim 6, the arcuate gear sets being supported on a face of the pinion, the cam means being two cams also on a face of the pinion and each having such angular relationship to a gear set that it can actuate the latch release just after the hammer is fully raised against the spring means.

8. In the hammer of claim 1: the hammer member comprising a slide and a hammer head removably secured to the slide.

9. In the hammer of claim 1: a vertical column, the hammer member comprising a hammer slide mounted for reciprocation on the column, the column and slide being non-circular in cross section and complementary, to permit the reciprocation but prevent twisting of the slide about the column.

10. In the hammer of claim 9, the column being hollow, and the spring means being a coil spring confined in the column.

11. In a power hammer: a housing; a column in the housing; a hammer slide supported on the column for reciprocating movement thereon; a hammer head on the slide; spring means urging the slide in a hammer-driving direction; a rack on the slide, a gear having arcuate, angularly spaced gear sets engageable with the rack on the slide during rotation of the gear to displace the slide against the spring means, the angular spaces between the gear sets affording intervals for return of the hammer by the spring means; and releasable latch means for holding the slide in its displaced position against the spring means, the latch means including interengageable latching elements the first of which is attached to the slide and the second is movably mounted on the housing for displacement to and from engagement with the first; selectively operable means to produce interconnection between the second latching element and the gear to cause the gear to disengage the latching elements in a predetermined relation to the position of the rack, to prevent release of the latch and the hammer slide when an angular space is presented to the rack so as to prevent clash of the slide rack and the gear sets.

12. In the hammer of claim 11, the column and slide being non-circular to permit the reciprocation but prevent relative twisting.