WO2014166950A1

WO2014166950A1 - Safety knife comprising two blades

Info

Publication number: WO2014166950A1
Application number: PCT/EP2014/057060
Authority: WO
Inventors: Jean-Claude Peyrot
Original assignee: Mure Et Peyrot
Priority date: 2013-04-09
Filing date: 2014-04-08
Publication date: 2014-10-16
Also published as: FR3004135B1; FR3004135A1

Abstract

The invention concerns a knife provided with a first blade (1) in the bottom of a groove (5) in a body (2) of the knife at a first end of the body of the knife and a second blade (3), that can be extracted at a second end of the body of the knife that comprises a safety device provided with a bistable element (4a, 4b) that can be moved between a first position (A) and a second position (B), said device closing the entrance of the groove (5) and releasing the extractable blade (3) when in the first position (A), and opening the entrance of the groove (5) and holding the extractable blade (3) in a retracted position when in the second position (B), the device further comprising a control means (6) for controlling the bistable element that is designed to allow the device to switch from one of said positions (A, B) to the other of said positions (B, A) by pushing the control means with a force higher than a switching threshold of the bistable element.

Description

SAFETY KNIFE HAVING TWO BLADES

Background of the invention

Field of the invention

The present invention relates to a safety knife having two blades and provided with a safety device to protect the operator of a blade when using the other.

Technological background

One type of knife known and used for opening cartons consists of a handle whose end has a diagonal groove provided with a groove bottom blade, suitable for cutting strings or strapping means in the form of plastic strips, and the other end has a removable blade under the action of a pusher and secured to a return spring of the blade in the retracted position in the handle of the knife.

When the knife is used to cut the cartons or adhesive tapes closing cartons, the blade groove bottom is relatively protected by the body of the knife and, unless to hang the knife at the groove, for example with a garment, it is unlikely to cut with the blade in groove bottom.

On the other hand, when the groove bottom blade is used, the operator holds the knife by the part of the handle from which the extractable blade normally leaves, which is more dangerous.

There are also safety devices for locking an extractable blade in the retracted position and devices ensuring automatic return of such a blade in the knife body at the end of cutting.

Brief description of the invention The object of the present invention is to increase the safety of knives with two blades, such as knives with a bottom blade and an extractable blade, by proposing a device that prevents access to one of the blades when the other is used.

To do this, the present invention provides a knife provided with a first blade at the bottom of a groove of a knife body at a first end of the knife body and a second blade, extractable at a second end of the knife body, the knife comprising a safety device provided with a bistable element and movable between a first position and a second position, the safety device realizing in the first position a closure of the entrance of the groove and a release of the second blade and, in the second position, an opening of the groove inlet and a holding of the second blade in a retracted position, the safety device further comprising a control means of the adapted bistable element allowing the passage of said device from one of said positions (A, B) to the other of said positions (B, A) by pushing on the means for controlling a force beyond a tipping threshold of the bistable element.

Advantageously, the bistable element comprises a spring means adapted to recall the safety device in one or the other of said positions around an unstable point.

The spring means being constituted by a spring blade, the safety device preferably further comprises ball joints positioned so as to compress the lamella thus to bend the lamella, the curvature of the lamella being reversed during the passage of the position to form the bistable element.

The knife comprising a movable sliding drawer of the second blade in the exit direction, is advantageously such that the safety device comprises a retaining latch of the movable drawer in a rear position of retraction of the blade.

The lock is advantageously pivotally mounted on an axis fixed in the body of the knife.

The lock is advantageously connected to the safety device by means of a spring link. The spring link is preferably positioned so as to allow the lock to fade to the passage of the movable drawer, in the direction of retraction of the extractable blade, and to return to the locking position of the drawer once the movable drawer back in the rear position reentry of the blade.

The safety device advantageously comprises a locking finger of the entrance of the groove in which the first blade is located.

The locking finger is preferably located at a first end of a body of the safety device sliding in a slider of the knife body.

The body of the safety device advantageously comprises the control means of said device and is extended by a rod, from which transversely two opposite arms of the blade, and which ends with the spring link and the lock.

Brief description of the drawings

Other features and advantages of the invention will become apparent on reading the following description of a nonlimiting exemplary embodiment of the invention with reference to the drawings which represent:

in Figure 1: an exploded view of an example of a knife provided with a device according to the invention;

in FIG. 2: a detail of embodiment of a bistable element that can be used for the invention;

FIGS. 3A and 3B: detailed views of the knife of FIG. 1 according to two positions of use of the safety device.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 shows a knife exploded and which comprises a main body 2 carrying at a first end a first blade 1 in a first housing provided with a groove 5 diagonal with respect to the longitudinal direction of the knife, the cutting part of the blade being disposed at the bottom of the groove.

To enclose the housing of the first blade 1, the knife comprises a first cover 21.

The body 2 of the knife comprises a second elongated housing in which there is a support device of a second blade 3 extractable at a second end 22 of the body 2 opposite the first end. In such a knife, the first blade serves for example to cut strings surrounding several cartons on a pallet and the second blade to cut the adhesive tapes for closing cartons.

The support device comprises a drawer 9 provided with an operating knob 91 to remove the blade 3 from the end 22 of the knife and a return spring 92 of the drawer.

According to this example the blade 3 is carried by a blade holder pushed by the slide and returned back by a second spring 93, as described in the patent application FR13 51287 incorporated herein by reference for which the blade 3 is of the type with automatic retraction at the end of the cut.

The drawer can however directly carry the blade, which in this case comes out and returns by pushing and releasing the push button 91.

A second cover 23 closes the body 2 of the knife at the second housing.

According to the invention, the knife comprises a safety device provided with a bistable element.

According to Figure 1 the bistable element comprises a spring means consisting of a spring strip 7a, the device further comprises stops of ball joints 8a, 8b of compression of the strip so as to bend the strip.

To do this, the strip is of greater length than the distance between the stops 8a, 8b.

To allow the operation of the device, the stops 8a, 8b are configured in an arc to make rotten connections allowing rotation of the ends of the blade.

As will be seen later, the bistable element is adapted to recall the safety device in a first or a second position around an unstable point.

Still according to Figure 1, the safety device comprises a latch 10 for retaining the movable drawer 9 in a rear position of retraction of the blade.

The lock is pivotally mounted on an axis 16 fixed in the body 2 of the knife.

The lock 10 is connected to the safety device by means of a spring link 12 which is positioned so as to allow the latch 10 to fade as the movable drawer 9 passes in the retractable direction of the extractable blade 3 and to return in locking position of the drawer once the movable drawer back to the back position of the blade.

The safety device further comprises a finger 13 for blocking the entrance of the groove 5 in which the first blade 1 is located.

According to the example, the locking finger is located at a first end of a body 1 1a of the safety device which slides in a slide 14 of the knife body and the latch 10 is located at the opposite end of the body 1 1 a.

The operation of the safety device is more particularly represented in FIGS. 3A and 3B.

The purpose of the safety device of the invention is to inactivate one of the blades 1, 3 when the other blade is in use.

For this purpose, in the case of FIG. 3A, where the blade 1 is accessible in the groove 5, the latch 10 blocks the slide 9 in the retracted back position of the extractable blade 3.

In the case of Figure 3B where the blade 3 is used, the locking pin 13 blocks the passage in the groove 5 while the latch 10 is in the retracted position to let the drawer 9.

There is therefore a movement of the safety device between two positions to alternately perform a deactivation of one blade or the other.

Figures 3A and 3B further illustrate the operation of the spring means constituted by the spring leaf 7a to achieve a bistable element which allows the device to remain in the position chosen by the operator.

According to this example, the stops of ball joints 8a, 8b compress the lamella and curvature so that it thus opposes a movement of the safety device.

To move the safety device must overcome the stiffness of the curved plate which amounts to push the device with a force beyond a tilting threshold of the bistable element constituted by the curved plate.

When the applied force is sufficient, the curvature of the lamella is reversed when passing from one to the other positions A, B.

The slat is made of plastic material stiff enough to have a spring function but flexible enough to allow jumping from one position to another. An alternative embodiment of the bistable element is shown in FIG. 2 for which a spring 7b pushes a ball that can move between two housings 201, 202 separated by a double ramp which constitutes an unstable point between the two housings which realize positions stable.

Returning to FIGS. 3A, 3B, the safety device moves between a first position (A) and a second position (B), the device producing in the first position (A) a closure of the entrance of the groove 5 and a release of the extractable blade 3 and, in the second position (B), an opening of the inlet of the groove 5 and a holding of the extractable blade 3 in a retracted position.

The safety device further comprises a means 6 for controlling the bistable element, here produced by grooves on the body 1 1 b thus adapted to allow the passage of the device from one of said positions (A, B) to the other of said positions (B, A).

The body 1 1 a extends to the opposite of the finger 13, by a rod 15 from which transversely two opposite arms of the blade 7a.

The rod then ends with the spring link 12 and the latch 10 which articulates in rotation on an axis 16 in the casing body 2.

The housing is closed by a cover 23 and the safety device comprises a plate 1 1a which snaps with the body 1 1b to maintain the device in the body of the knife by positioning on either side of a central partition in the groove 14 in which slides the safety device.

The invention is not limited to the example shown and in particular the knife can be a straight knife, the drawer 9 can also be shaped in-store for replacement blades.

Claims

R E V E N D I C A T IO N S

1 - Knife provided with a first blade (1) at the bottom of a groove (5) of a body (2) of the knife at a first end of the knife body and a second blade (3), extractable at level of a second end of the body of the knife, characterized in that it comprises a safety device provided with a bistable element (4a, 4b) and movable between a first position (A) and a second position (B), the safety device providing in the first position (A) a closing of the entrance of the groove (5) and a release of the second blade (3) and, in the second position (B), an opening of the entrance the groove (5) and a holding of the second blade (3) in a retracted position, the safety device further comprising a means (6) for controlling the bistable element adapted to allow the passage of the device of the one of said positions (A, B) to the other of said positions (B, A) by pushing on the control means of a force beyond a tilting threshold of the bistable element.

2 - knife according to claim 1 wherein the bistable element comprises a spring means (7a, 7b), adapted to return the safety device in one or the other of said positions around an unstable point.

3 - Knife according to claim 2 wherein, the spring means being constituted by a leaf spring (7a), the safety device further comprises ball joints (8a, 8b) positioned so as to compress the lamella so bending the slat, the curvature of the slat reverses when passing from one to the other positions (A, B), to form the bistable element.

4 - A knife according to any one of the preceding claims comprising a movable drawer (9) for pushing the second blade (3) in the exit direction, for which the safety device comprises a latch (10) retaining the drawer mobile (9) in a rear position of retraction of the blade.

5 - knife according to claim 4 wherein the latch is pivotally mounted on an axis fixed in the body (2) of the knife.

6 - knife according to claim 4 or 5 wherein the latch (10) is connected to the safety device by means of a spring link (12).

7 - Knife according to claim 6 for which the spring link (12) is positioned to allow the lock (10) to fade the passage of the drawer mobile (9) in the direction of retraction of the extractable blade (3) and return to the locking position of the drawer once the movable drawer back in the back position of the blade.

8 - A knife according to any one of the preceding claims for which the safety device comprises a finger (13) for blocking the entrance of the groove (5) in which the first blade (1) is located.

9 - Knife according to claim 8 wherein the locking finger is located at a first end of a body (1 1 a) of the safety device, sliding in a slide (14) of the knife body.

10 - Knife according to claims 3, 6 and 9 for which the body (1 1 a) comprises the control means (6) of the safety device and is extended by a rod (15), from which transversely two opposite arms of the leaf spring (7a) and which ends with the spring link (12) and the lock (10).