US 3857176 A
A knife with a retractable blade comprises a shell and a rigid side plate between which a blade carried by a blade carriage is held in a chosen position by means of a screw with an enlarged head against the side plate, a shank passing through registering slots in the plate and shell, and a nut slidably held in a channel in the shell. A spare blade magazine is slidably engaged in the rear end of the knife handle, and held by an integral resilient catch.
Claims available in
Description (OCR text may contain errors)
D United States Patent 1191 1111 3,857,176
Quenot Dec. 31, 1974 KNIFE WITH A RETRACTABLE BLADE 3,577,637 5/1971 lirlaginetz 30/162 3,660,895 5 1972 t 30 I62 [751 Invent Michel Quem" Besancon, France 3,708,881 11973 Beii nett 30l335  Assignee: Stanley-Mabo, Besancon, France Primary ExaminerAl Lawrence Smith  Ffled' 1973 Assistant Examiner.l. T. Zatarga  Appl. No.: 423,084 Attorney, Agent, or Firm-Prutzman, Hayes, Kalb &
Chilton  Foreign Application Priority Data Dec. 11, 1972 France 72.44004 ABSTRACT A knife with a retractable blade comprises a shell and  US. Cl. 30/162, 30/335 a rigid Side plate between which a blade carried by a [51 Int. Cl B261) 1/08 blade carriage is held in a chosen position by means of  Fleld of Search 30/162, a screw with an enlarged head against the side plate, a 30/163 shank passing through registering slots in the plate and shell, and a nut slidably held in a channel in the shell.  References C'ted A spare blade magazine is slidably engaged in the rear UNITED AT S PATENTS end of the knife handle, and held by an integral resil- 237,093 2/1881 Crowell 30/329 x ien hl,4l7,872 5/1922 Wall 30/162 2,404,141 7/1946 Nelson 30/162 5 Clam, 4 Drawmg Flgmes Willi/11111111! /IIIII II I I I I I I X j KNIFE WITH A RETRACTABLE BLADE The invention concerns knives with retractable blades used for cutting moquette carpets, linoleum and other sheet materials, and for other purposes.
The various knives of this type on the market are generally formed by a handle in two halves, assembled together longitudinally. The blade, fitted in a carriage slidably mounted inside the two halves of the handle, is interchangeable and may be locked in two or three protruding positions by means of notches provided in the blade.
The present-day types have the following drawbacks:
A lateral play of the blade, which adversely affects the precision of cutting, occurs due to the construction of the knife in two halves in a manner to provide an easy forward-rearward sliding of the carriage.
Moreover, there is a risk of permanently opening out the blade outlet slot in the event of excessive lateral efforts exerted on the edges of the said slot.
Setting the blade in a cutting position by means of only two or three notches does not enable the user to withdraw the exact length of the blade corresponding to the thickness of the material to be cut. This often leads to employing the knife with the blade protruding more than is necessary, which may involve a danger of breaking or undue wear to the tip of the blade.
Some knives also comprise a spare blade magazine in the rear part of their handle. The fitting in and, above all, the opening out of this magazine are generally controlled by a rudimentary button device liable to produce an untimely opening out as a result of an unintentional pressure of the hand on the said button during cutting.
An object of the invention is to provide a construction of a knife handle which eliminates the mentioned drawbacks, is convenient to use, and well adapted to the sought-after use.
According to the invention, a knife handle comprises a hollow elongate shell, a rigid elongate side plate, a bladecarrying carriage movably mounted between the shell and side plate, and means for gripping the carriage between the shell and side plate in selected positions along the handle. The carriage gripping means include: means definining registering elongate slots along the side plate and the shell, the slot in the shell communicating with an enlarged elongate rail-forming channel towards the outer face of the shell; a screw having an enlarged head bearing against the side plate and a shank passing through said slots into said channel; a nut threadably engaged on said shank, the nut being held in said channel for sliding movement therealong but against rotation relative to the shell; and means defining an aperture in the carriage for receiving said screw. The enlarged head is manually rotatable between a first position in which it can be moved bodily with the screw, nut and carriage by sliding of said shank along said slots, and a second position in which it is fixed with the carriage firmly gripped between the shell and plate in any given position of said shank along said slots.
This construction offers the advantage that during use the blade carriage and a blade carried thereby are firmly held in a blade outlet slot defined between the shell and the side plate; this slot cannot be permanently enlarged as a result of use, since its opposing faces are held as close as possible together by suitably turning the enlarged head of the screw.
Moreover, the length of the blade tip protruding from this slot can be altered progressively and therefore set at an exact value according to the material to be cut. Furthermore, it is possible to ensure easy replacement of a blade, by simply turning the head to loosen the plate from the shell, without fully dismantling the plate from the shell.
Further features of the invention will be apparent from the following description of a preferred embodiment made by way of example and with reference to the accompanying drawings, in which:
FIG. 1 is an elevational view of one side of a knife;
FIG. 2 is a cross-section taken along line llll of FIG. 1;
FIG. 3 is an elevational view of the other side of the knife; and
FIG. 4 is an enlarged scale elevational view similar to FIG. 1 but with a side plate of the knife handle removed.
The knife shown comprises a hollow elongate shell 1 with a retractable blade 2 whose position is controlled by means of an enlarged knurled head 3 of a screw whose shank 6 is slidably mounted along an elongate slot 4 in a rigid stainless steel side plate 5 and a registering elongate slot 4' in shell 1. The shank 6 passes through a hole 12 in a blade-supporting carriage 7 and its threaded free end is screwed into a nut 8 which can slide, but not rotate, in a channel 9 opening into the outer face of shell 1, this channel communicating with slot 4' and being provided with a rigid metallic support plate 23.
The carriage 7 (FIG. 4) is formed by a metalplate with its upper and lower edges bent over perpendicularly to form rails slidably engaged in cooperating channels (not shown) in shell 1. The upper edge (looking at FIG. 4) also has two bent over catches 14. A resilient tongue 13 is cutout in the central part of carriage 7 and is curved to normally slightly protrude out of the plane of the plate towards the same side as the upper and lower edges and catches 14.
A trapezoidal blade 2 having two rounded notches 15 in its shorter, non-sharpened parallel edge is fitted in carriage 7 by engagement of one of its notches 15 in the forwardmost catch 14, and with its rear edge resting against the rearmost catch 14. This blade 2 can be inserted into carriage 7 through an inclined slot 10 formed between the tapered nose end 11 of shell 1 and plate 5 when the screw head 3 is loosened sufficiently. As the head 3 is tightened, spring 13 is'deformed by blade 2 until the position shown in FIG. 2 is reached, in which the blade 2 (and carriage 7) are tightly held in slot 10 between nose 11 and plate 5, and the shank 6 is so tightly screwed in nut 8 as to prevent movement of the shank 6 along slots 4 and 4'. In this position, the protruding blade 2 can be used with the inclined face of slot 10 acting as a bearing surface. The tight gripping provided by screw head 3 avoids any unwanted defor- .mation of slot 10 or shaking of blade 2.
When the screw head 3 is slightly loosened, the shank 6 can be slid along slots 4 and'4' to another position, and the blade 2 and carriage 7 set in this new position by tightening screw head 3. However, by further loosening screw head 3, the tongue 13 can push blade 2 away from the body of carriage 7 until notch 15 is disengaged from catch 14. The blade 2 can then be removed and replaced, or turned around and reinserted with its other notch 15 engaging with catch 14, without a need to fully dismantle plate from shell 1.
A spare blade support or magazine 16 is slidably mounted in a recess in the rear end of the handle. A resilient catch 17 moulded integrally with magazine 16 in a synthetic plastic material comes either to engage on an inner boss 18 in shell 1 to releasably hold magazine 16 wholly within the handle, or against a rearwardly disposed protuberance, disposed above a through-hole 22, to prevent full withdrawal of magazine 16. Magazine 16 includes semi-circular recesses 19 in the upper edges of its walls to facilitate removal of blades in the withdrawn position of the magazine. Withdrawal of magazine 16 by a pulling action is facilitated by the provision of a nail-engaging recess 21 in shell 1. Withdrawal of the magazine 16 can in no event be provoked by an unwanted movement during cutting. Hole 22 serves for the passage of a cord or the like for suspending the knife.
Although the screw head 3 is shown as having a diameter equal to the width of the handle in a direction generally parallel to the plane of head 3, it could have a greater diameter. Also, head 3, instead of being formed by a separate part of synthetic plastic material moulded about a hexagonal head of the screw, could be integral with the screw.
The slot 4', instead of being formed in the shell 1, could be formed solely in a squared substantially C- section metal support fixed in an opening in the shell, the outer face of this support closing the opening while its open inner face forms the slot 4.
Various other modifications to the described embodiment will readily occur to persons skilled in the art without departing from the scope of the appended claims.
What is claimed is:
l. A knife handle comprising a hollow elongate shell, a rigid elongate side plate, a blade-carrying carriage movably mounted between the shell and side plate, and means for gripping the carriage between the shell and side plate in selected positions along the handle, said carriage gripping means including: means defining registering elongate slots along the side plate and the shell, the slot in the shell communicating with an enlarged elongate rail-forming channel towards the outer face of the shell, a screw having an enlarged head bearing against the side plate and a shank passing through said slots into said channel, a nut threadably engaged on said shank, the nut being held in said channel for sliding movement therealong but against rotation relative to the shell, and means defining an aperture in the carriage for receiving said screw, said enlarged head being manually rotatable between a first position in which it can be moved bodily with the screw, nut and carriage by sliding of said shank along said slots, and a second position in which it is fixed with the carriage firmly gripped between the shell and plate in any given position of said shank along said slots, said carriage including blade engaging means for movement of a blade with the carriage and automatic blade releasing means operably responsive upon movement of said head toward and beyond said first position to release the blade from said blade engaging means without relative angular movement of said shell and said side plate.
2. A knife handle according to claim 1, in which said enlarged head is circular and knurled and has a diameter at least as great as the width of the handle in a direction generally parallel to the plane of said head.
3. A knife handle according to claim 1, in which said blade engaging means includes a projection for engaging with a blade, and said blade releasing means includes an integral curved resilient tongue adapted to be deformed by a blade engaging with said projection when the enlarged head is in said second position and to move the blade out of engagement with said projection as the enlarged head is rotated towards or beyond said first position.
4. A knife handle according to claim 1, comprising a spare blade support slidably mounted in said shell along the longitudinal direction of the handle, said support including an integral resilient catch cooperating with means on the shell for selectively locking the support in a first position wholly within the handle and in a second position withdrawn from the handle.
5. A knife handle according to claim 1, in which said side plate is in stainless steel.