Holder for detachable blades

A holder for a detachable blade has a handle part and a blade retaining part formed by a pair of body sections pivotally connected for movement between open and closed positions. A latch member supported within the hollow handle part, and which retains the body sections in closed position, is released by manually operating an associated push button disposed in an aperture in the handle part. Coengageable clamping surfaces on the blade retaining part cooperate in clamping engagement to retain a blade in the holder when the holder is closed. A thumb rest on the blade retaining part reduces risk of accidental contact with a blade secured in the holder.

BACKGROUND OF THE INVENTION 
This invention relates in general to cutting tools and deals more 
particularly with an improved holder for detachable blades. The tool of 
the present invention may be used as a utility knife or general purpose 
cutting tool, but is particularly adapted for use as a carpet installation 
tool. 
Holders for detachable blades are well known in the art and typical holders 
of the type with which the present invention is concerned are illustrated 
and described in U.S. Patents to Cuscovitch, U.S. Pat. No. 3,604,113, 
issued Sept. 4, 1971 and U.S. Pat. No. 4,261,104, issued Apr. 14, 1981. 
Each of the blade holders illustrated and described in the aforementioned 
U.S. patents is adapted to hold a double edged, apertured blade and has 
elongated pivotally connected body portions movable relative to each other 
between open and closed positions. When the holder is open a blade may be 
attached to or removed from it. When the holder is in its closed or 
working position the blade is retained in fixed position in the holder. 
The blade holder shown in the earlier aforementioned U.S. patent has a 
latch member pivotally connected to one of its body sections by a 
relatively short pivot pin. This latch member is prone to loosen from 
repeated use and generally lacks desired blade retention capability. The 
improved blade holder shown in the later issued patent to Cuscovitch has a 
ball detent mechanism for releasably retaining its body sections in closed 
position. However, the latter arrangement is not entirely satisfactory, 
because it does not positively secure the body sections in closed 
position. Further, the double-edged blade used in a holder of the 
aforedescribed general type has an edge exposed at the upper side of the 
holder beyond the tip of the holder and presents a potential source of 
hand or finger injury to the user. 
It is the general aim of the present invention to provide an improved 
holder for detachable blades such as aforedescribed which includes 
improved means for positively retaining the body sections of the holder in 
closed or blade retaining position, but allows quick release, so that the 
holder may be opened to facilitate rapid blade change, when required. A 
further aim of the present invention is to provide a holder for a 
detachable blade having an improved blade retention arrangement and 
including an improved safety feature to reduce risk of accidental finger 
contact with a blade edge when the holder is in use. 
SUMMARY OF THE INVENTION 
In accordance with the present invention an improved holder for a 
detachable blade comprises an elongated handle portion and a blade 
retaining portion which extends from the handle portion and terminates at 
a tip. The holder includes two relatively movable body sections connected 
for pivotal movement about an axis which extends transversely of the 
holder between an open position wherein the blade is detachable from the 
holder and a closed position wherein the blade is retained in fixed 
position in the holder. The body sections have opposing surfaces which are 
disposed in mating engagement in the closed position. A latch mechanism 
for releasably retaining the body sections in closed position includes a 
latch member supported on one of the body sections for movement between 
latching and releasing positions relative to the other of the body 
sections. The latch member has a manually operated actuator which is 
disposed within an aperture in the holder and which is operable to move 
the latch member from its latching to its releasing position. The blade 
retaining portion of the holder is preferably downwardly inclined from the 
handle portion in the direction of the tip and carries an upwardly 
projecting thumb rest adapted to prevent accidental thumb contact with the 
blade when the tool is in use. A lip on each blade retaining portion 
cooperates with the other blade retaining portion to secure a blade in 
fixed position within the holder.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Turning now to the drawings, and referring first particularly to FIGS. 1-6, 
a holder for a detachable blade embodying the present invention is 
indicated generally by the reference numeral 10. In FIGS. 1 and 2 the 
holder 10 is shown with a double-edged apertured blade B releasably 
retained therein. The illustrated holder and blade assembly is suitable 
for use as a general purpose cutting tool, but is particularly adapted for 
use as a carpet installation tool. The double-edged blade B has an 
elongated aperture or slot, indicated at S, and may be reversibly 
positioned within the holder 10 to expose either of the blade edges in a 
cutting position, as will be hereinafter evident. 
The holder 10 generally comprises a pair of body sections which includes a 
righthand section, indicated generally at 12, and a lefthand section, 
designated generally by the numeral 14. The sections 12 and 14 are 
connected together by a threaded fastener 16. The body sections pivot 
about an axis 17 which extends transversely of the holder, between open or 
blade receiving positions, such as the position shown in FIG. 3 and a 
closed or blade retaining position, shown in FIGS. 1 and 2. A latching 
mechanism, indicated generally at 18, releasably retains the body sections 
in closed position, as will be hereinafter further discussed. In the 
closed position the body sections 12 and 14 cooperate to define an 
elongated handle part 20 and a blade retaining part 22 which is inclined 
forwardly and downwardly from the handle part and terminates at a tip 24, 
as best shown in FIG. 1. 
Considering the holder 10 in further detail, the right and left hand body 
sections 12 and 14 are preferably diecast parts and have opposing inner 
surfaces indicated at 26 and 28, respectively, which are disposed in 
mating engagement within a common plane when the holder 10 is in closed 
position, as best shown in FIG. 2. The body section 14, shown in detail in 
FIGS. 13-16, has a shallow forwardly opening recess 30 in its blade 
retaining portion, the latter portion being designated by the numeral 31. 
The recess 30 has a width approximately equal to the width of the blade B 
and a depth approximately equal to the thickness of the blade. A blade 
mounting projection 32, integrally formed on the blade retaining portion 
of the body section 14 projects from the recess 30 inwardly and beyond the 
inner surface 28, as best shown in FIGS. 14-16. The mounting projection 32 
is shaped to complement at least a portion of the slot S and is preferably 
sized to allow the blade B to be moved forwardly and rearwardly within the 
recess 30 when the holder 10 is in its opened position, so that projection 
of the blade B beyond the tip 24 may be adjusted, as desired. 
An integral lip 34 formed on the blade retaining portion of the body 
section 14 extends laterally outward beyond the inner surface 28 and along 
the lower edge of the blade retaining portion. The lip 34 defines an 
inwardly facing clamping surface 36 which preferably forms an angle of 
approximately 15 degrees with the plane of the inner surface 28, as best 
shown in FIG. 14, where the latter angle is indicated by the numeral 40. 
The blade retaining portion of the body section 14 is relieved along its 
upper margin and defines an outwardly facing clamping surface 38 for 
generally complimentary coengagement with an associated inwardly facing 
clamping surface on the other body section 12 when the holder is closed, 
as will be hereinafter further discussed. 
The handle portion of the body section 14 is hollow and has ribs 42 and 44 
therein which extend transversely thereacross and are recessed to define a 
storage compartment for extra blades, as best shown in FIGS. 2 and 13. An 
integral boss 46 is formed within the hollow handle portion of the body 
section 14 proximate the junction of the handle portion and the blade 
retaining portion and has a stepped bore 48 for receiving an associated 
portion of the fastener 16. The bore 48 extends transversely through the 
body section 14, as shown in FIGS. 13 and 16. The outer end of the bore 48 
has a hexagonal configuration for receiving a nut, which comprises part of 
the fastener 16. Another boss 50 within the rear end of the handle portion 
14 defines a strike surface 52 which cooperates with the latch mechanism 
18, as will be hereinafter further discussed. 
The righthand body section 12, shown in detail in FIGS. 7-12, has a recess 
54 in its blade retaining portion which opens inwardly and downwardly for 
receiving an associated portion of the mounting projection 32 when the 
holder 10 is in its closed position. A lip 56 projects outwardly from the 
blade retaining portion beyond the inner surface 26 and defines an 
inwardly facing clamping surface 58 which forms an angle of approximately 
15 degrees with the inner surface 26, the latter angle being indicated by 
the numeral 60 in FIG. 8. The blade retaining portion of the body section 
12 is relieved along its lower margin and defines an outwardly facing 
clamping surface 61 for generally complementary coengagement with the 
clamping surface 36 on the opposite body portion 14 when the holder 12 is 
in its closed position. 
The body section 12 has an integral upwardly projecting thumb rest 62 which 
defines a generally rearwardly facing surface 64 on the upper part of its 
blade retaining portion between its tip and its handle portion. The handle 
portion of the body section 12 is hollow and has an integral boss 66 
therein proximate the junction between the handle portion and the blade 
retaining portion. The inner end of the boss projects inwardly beyond the 
surface 26, as shown in FIG. 11, and is sized to be received within the 
counterbore at the inner end of the bore 48. A bore 68 extends through the 
boss 66 for receiving an associated portion of the fastener 16 and is 
countersunk at its outer end to receive the head of the fastener 16. 
A generally cylindrical inwardly projecting boss 70 is formed within the 
rear portion of the handle section 12 and defines an aperture 72 which 
opens outwardly through the body section. An outwardly facing seating 
surface 74 is formed within the aperture 72 at the forward inner end of 
the boss 72, as best shown in FIGS. 5 and 12. A pair of laterally spaced 
apart parallel ribs 76, 76 extend rearwardly from the circular boss 70 to 
the rear wall of the handle portion 12 and have generally U-shaped 
inwardly opening fulcrum recesses 78, 78, formed therein, as best shown in 
FIGS. 7 and 12. 
The latch mechanism 18 includes a latch lever, indicated generally at 80 
and best shown in FIGS. 17-19. The latch lever is preferably die cast and 
is supported for pivotal movement about an axis which extends transversely 
of the longitudinal axis of the handle part 20. It includes an integral 
pivot pin 82 which is received and supported in the fulcrum recesses 78, 
78. A push button portion 84 at one end of the latch lever 80 is received 
within the aperture 72. An integral latching element 86 at the opposite 
end of the latch lever includes a latch surface 87 for latching engagement 
with the strike surface 52. An inclined cam surface 88 on the latch 
element 86 is adapted to engage an edge portion of the body section 14 
which cams the latch lever 80 into the recess within the body section 12 
when the body sections are pivoted relative to each other and to the 
closed position. A biasing spring 90 disposed in a recess between the ribs 
76, 76 and shown in FIG. 5 acts between the body section 12 and the latch 
lever 80 to normally bias the latch lever toward its latching position. 
When the holder is in its closed position the coengageable clamping 
surfaces 38, 58 and 36, 61 are respectively engaged to retain the blade B 
in the holder 10, as shown in FIG. 4. In the closed position the latch 
surface 87 is engaged with the strike surface 52 and positively retains 
the blade holder 10 in its closed position. The latch lever 80 may be 
readily released from its latching position by manually depressing the 
push button 84, which allows the holder to be opened for blade adjustment, 
removal and replacement.