Automatic screwdriver jaws for face frame holes

Screw fastener jaws for the driver head of an automatic screw feeding and driving apparatus are disclosed for driving screws in face frame drilled holes. A tubular mandrel communicates with a screw feeding passage and a screwdriver passage at a first end to feed screws into the channel and then drive the screws. Spring action moves a plate to close off the free end of the channel to capture the screw. The plate is wide enough to engage the workpiece surface on both sides of the slanted hole. As the mandrel is advanced into the slanted hole, the plate is forced away from the end of the mandrel, releasing the screw for driving into the workpiece.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to automatic screw feeding and driving machines and 
more particularly to the jaws holding a screw in those machines especially 
adapted for inserting the screw into face frame drilled holes. 
2. Description of the Prior Art 
Automatic screw feeding machines are exemplified by the apparatus disclosed 
in U.S. Pat. No. 5,234,127. They feed screws automatically from a random 
batch of screws and deliver them one at a time as needed to a screw holder 
and driver mechanism. 
Screw holding and driving mechanisms used with these machines are 
exemplified by U.S. Pat. No. 4,671,143. They are provided with jaws which 
hold the head of the screw with the threaded shank extending outward 
therefrom for insertion into a hole in the workpiece. As the shank is 
rotatably advanced by the driver into the hole, the head is released and 
the screw driven home. These devices are quite effective in the common 
situation where the hole in the workpiece is orthogonal to the surface. If 
the head of the screw must not project above the work surface, the hole 
may be countersunk and a flat head screw employed. 
Many construction techniques join two pieces at right angles by using a 
slanting hole in one piece with a slanting countersunk hole where that 
surface will not be seen. This is termed face frame drilled holes and it 
is commonly employed in fabricating frames that will be covered with 
veneers, such as kitchen cabinets. The screw holding jaws of the prior art 
devices cannot clear the slanted countersunk holes commonly used in this 
construction. Consequently, the holes must be made larger or the technique 
cannot effectively use the automatic screw feeding, holding and driving 
machinery. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the invention to provide automatic screw 
holding and feeding apparatus that can be used effectively for fastening 
workpieces together that employ face frame drilled holes for the screw 
fasteners. 
It is another object that the device be of simple economical construction 
with a minimum of moving parts. 
It is yet another object that the apparatus be transformed by a single 
simple motion from a first condition in which the threaded fastener is 
safely enclosed within a chamber to a second condition in which the point 
of the fastener is released and positioned correctly for driving into the 
slanted hole. The screwdriver jaws of the invention include a tubular 
mandrel that, at a first end, communicates with two passages, a first 
passage through which a screw is pneumatically blown and a second passage 
through which the rotary fastener driver or screwdriver passes. Pivotally 
connected to the mandrel is a hood or cover that is spring biased to a 
first condition in which the hood covers the second or free end of the 
mandrel to provide a chamber enclosing the screw and holding it in a 
desired position. Since the screw may be blown into the mandrel with 
considerable velocity, it is important for safety considerations that the 
point be covered. 
The pivotal construction of the cover is arranged so that as the mandrel 
and driver are moved into the sloping countersunk hole in the surface of 
the workpiece, the cover engages the surface of the workpiece and 
automatically uncovers the second or open end of the mandrel, exposing the 
screw in the correct position for driving into the hole by the driver. 
These and other objects, advantages and features of the invention will 
become more apparent when the detailed description is studied in 
conjunction with the drawings in which like elements are denoted by like 
reference characters.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now first to FIGS. 1-7, the jaw apparatus 1 comprises an elongate 
tubular mandrel 2 having an axial channel 3, a movable cover 4 with a 
plate 5 that covers the open end 6 of the channel in a first mode of 
operation, urged by compression spring 7. The other end 8 of the channel 
is in communication with two converging passages, a first passage 9 
connected to known one-at-a-time pneumatic fastener feeding apparatus 10, 
and a second passage 11 connected to the housing 12 of a well known 
fastener driver apparatus coaxially aligned with the channel. Fastener 
driver 13 may have a screwdriver tip 14 or other fastener engaging tip as 
required. The driver 13 is spring loaded to retreat behind the junction 15 
of the passages while a fastener 16 is blown into the channel and stopped 
by plate 5. The fastener is held safely within the compartment formed by 
the channel and the plate as the apparatus is positioned at a face frame 
hole 17 cut slantingly in a first workpiece 18 to be joined to a second 
workpiece 19 as shown in FIG. 6. The plate 5 is wide enough to extend to 
the surface 20 on both sides of the hole 17 routed (FIG. 5) or drilled 
(FIG. 6) slantingly into the surface of workpiece 18. When the housing 12 
of the driver apparatus is pushed forward in the usual manner of operation 
of such machines, the fastener driver tip 14 advances past junction 15, 
rotating and engaging the threaded fastener 16. As the mandrel moves down 
into hole 17, the plate 5, engages both surfaces 20 on the sides of the 
hole and is forced upward and away from covering open end 6 of the 
channel. This allows the fastener to be driven through the remainder 21 of 
the hole in workpiece 18 and into the second workpiece 19, thereby joining 
the two with a fastener whose head is below surface 20. The cover 4 is 
comprised of two parallel opposed side panels 22 joined to plate 5 and a 
top panel 23 joined to the plate and side panels. A roll pin 24 in the 
side panels pivotally joins the cover to the mandrel, and compression 
spring 7 between cover and mandrel urges the plate to cover the channel 
when not being forced away as the mandrel enters the hole. 
The tip 6 of the mandrel may take the half-cylindrical shape shown in FIG. 
4 with the external sectional shape 25 being rectangular to conform to the 
shape of the hole cut by a router as shown in FIG. 5. 
Alternatively, the tip end 6 of the mandrel may take the straight square 
cut shape shown in FIG. 2 with the external sectional shape 25 being 
cylindrical to conform to the shape of the hole cut by a drill as shown in 
FIG. 3. 
Referring now to FIG. 8, in an alternative embodiment of the invention, the 
cover comprises an elongate spring attached at a first termination 27 to a 
plate 5 and at a second termination 28 to the mandrel. The bottom of plate 
5 where it contacts the workpiece surface is provided with a curved lip 29 
for reduced frictional resistance. The spring, plate and lip may be formed 
from a single piece of material, such as spring steel. 
The above disclosed invention has a number of particular features which 
should preferably be employed in combination although each is useful 
separately without departure from the scope of the invention. While I have 
shown and described the preferred embodiments of my invention, it will be 
understood that the invention may be embodied otherwise than as herein 
specifically illustrated or described, and that certain changes in the 
form and arrangement of parts and the specific manner of practicing the 
invention may be made within the underlying idea or principles of the 
invention within the scope of the appended claims.