EP1985417B1 - Safety knife with system for automatic blade retraction after cutting - Google Patents

Description

The present invention relates to a safety knife with automatic blade retraction device at the end of cutting.

As part of the protection of operators operating knives comprising a blade protruding longitudinally from a knife body for cutting objects such as packaging, cartons, plastic films, it is known to arrange the blade on a door blade operated by an operating device such as a pusher and to provide means for disengaging the pusher and the blade holder at the end of cutting.

The document DE 43 15 495 A1 provides in particular a device for which the blade holder comprises a cam path receiving a pin carried by the knife body when the blade holder is pushed by a pusher and for which a tilting of the blade holder under a cutting force positions the pin against a temporary stop integral with the cam path so that when the force is canceled, the nipple escapes the temporary stop and the blade holder retracts inside the knife body under the action of a return spring.

This device is however difficult to implement because uses means for driving the blade holder by the pusher allowing a release of the blade holder at the end of thrust made by a system of drive stops for exceeding the pusher beyond the blade blade drive abutment when hooking the blade holder on the stud which causes a jolt during the transition of the blade holder from the position where it is pushed by the pusher to the position where the blade holder n is more guided by the pusher.

In addition, the dimensioning of the drive stops of the cam path and the position of the stud are difficult to control in order to obtain an operation every time without inadvertent retraction of the blade or blocking of the pusher and the blade holder.

The object of the present invention is to provide a safety knife with an automatic blade retraction device at the end of cutting, comprising an arming of the retraction device by prior rotation of the blade holder under the cutting force, offering good positioning accuracy. blade door being cut while avoiding the risk of inadvertent retraction of the blade holder during cutting.

To this end, the present invention relates to a safety knife with an automatic blade retraction device at the end of cutting, comprising a blade holder and an operating pusher of the blade holder sliding longitudinally in the body of the knife to bring out the blade carried by the blade. blade holder of the knife body, for which the blade holder and the operating pusher are connected by a first spring member applying a first driving abutment, part of the pusher, against a second driving abutment of the blade holder, said first and second stops being adapted to disengage by rotation of the blade holder relative to the pusher under a cutting force (E).

en figure 1:

une vue en éclaté du côté droit d'un couteau selon l'invention;

en figure 2:

une vue en éclaté du côté gauche du couteau de la figure 1;

en figure 3:

une vue en éclaté d'un détail de l'avant du couteau de la figure 1 capot droit enlevé;

aux figures 4A, 4B et 4C:

des vues de côté gauche du couteau de la figure 1, capot droit enlevé et porte lame respectivement en position avancée, en position de coupe inclinée et en position rétractée;

en figure 5:

une vue partielle de l'avant du couteau

Other characteristics and advantages of the invention will be apparent from the following reading of a nonlimiting exemplary embodiment of the invention with reference to the drawings which represent:

in Figure 1:

an exploded view of the right side of a knife according to the invention;

in figure 2:

an exploded view of the left side of the knife from the figure 1 ;

in Figure 3:

an exploded view of a detail of the front of the knife from the figure 1 right hood removed;

in FIGS. 4A, 4B and 4C:

left side views of the knife from the figure 1 , right cover removed and blade holder respectively in the advanced position, inclined cutting position and retracted position;

in Figure 5:

a partial view of the front of the knife

The figures 1 and 2 represent an example of a safety knife 1 with automatic blade retraction device at the end of cutting according to the invention seen in exploded respectively the right side and the left side.

The knife comprises a body composed of two half-shells 11a and 11b, a blade 26 carried by a blade holder 2.

The left half-shell is truncated to make it possible to make a removable hatch 25 to allow a blade change 26.

The blade holder 2 receiving the blade 26 is mounted on a pusher 3 for actuating the blade holder.

The pusher 3 slides longitudinally in the knife body to bring out the blade 26 carried by the blade holder 2 of the knife body.

According to the invention, the blade holder and the operating pusher are connected by a first spring element 4 applying a first driving abutment 5, part of the pusher, against a second abutment 6 for driving the blade holder and the first and second stops 5, 6 are adapted to disengage by rotation of the blade holder relative to the pusher under a cutting force E.

The blade holder is applied to one side of the pusher and the second driving abutment 6 is received in a window 7 of the pusher making a cam path defining an advanced position and a retracted position of the blade holder relative to the pusher.

The blade holder is guided longitudinally between the left half-shell 11b and the pusher 3 to remain parallel to the pusher.

The spring 4 is a coil spring provided with hooking rings at each of its ends, a first ring clinging to a pin 14 protruding from the face of the blade holder resting on the pusher and a second ring clinging to a pin 15 carried by the pusher, the spring being tensioned when the first and second stops 5, 6 are engaged to be able to return the blade holder back when the stops are released.

The pin 14 of the blade holder is disposed in a window 7 cut in the pusher and realizing the cam path receiving the second drive stop.

The first drive stop 5 consists of a stop of a ramp 8 made in the cam path of the window 7.

The figure 1 in particular represents the blade holder with its abutment 6 engaged with the abutment 5 of the pusher.

When the abutment 5 and the abutment 6 are disengaged from each other, in the absence of retaining means, the blade holder moves back with respect to the pusher under the action of the spring 4 and the pawn 14 moves back into the window and comes into abutment against the bottom of the window.

As represented in figure 2 to permit cutting, the blade holder 2 comprises a finger 9 adapted to bear against a shoulder 10 of the knife body 11a, 11b and to hold the blade holder 2 in a cutting position inclined with respect to operating pusher 3.

To use the knife there is therefore a knife operation in three stages.

First, the pusher moves back into the body so that the stop 6 for driving the blade holder goes up on the ramp 8 and is engaged against the drive stopper 5 of the pusher.

Then the pusher is pushed forward by an operating means such as a button coming out of the knife body or the operating means described below in the form of a rotary trigger 16 and the pusher and the blade holder take the position represented in Figure 4A to take out the blade 26.

Finally, when the operator applies the blade to the object to be cut, the blade holder rotates under the cutting force E represented by the arrow in Figure 4B this disengages the drive stops and comes to bear the finger 9 against the shoulder 10 of the right half-shell 11 by rotation and retreat of the blade 26 here shown in dashed lines.

Once the cut is over or when the operator releases his effort, the spring 4 tilts the blade holder, which disengages the finger 9 from the shoulder 10 and brings the blade holder to the position shown in FIG. figure 4C retracted into the knife body.

To stop the retraction of the blade door disengaged from the pusher, the blade holder has a first rear stopper 20 cooperating with a second rear stopper 21a, 21b carried by the knife body.

The pusher is thus adapted to move back into the body under the action of the first spring element in a reengagement position of the drive abutments 5, 6 of the blade holder and the pusher.

Back to the figure 1 , to assist the rotation of the blade holder relative to the pusher, the blade holder 2 comprises a pin 12 sliding in a longitudinal groove 13 of the pusher and forming an axis of rotation of the blade holder relative to the pusher.

As represented in figure 3 , the second rear stopper 21b may be the front of a pusher trigger and the first rear stop 20 a rear shoulder of the blade holder.

In addition or alternatively, the second rear stopper is a pad 21a of a half-shell as shown in FIG. figure 4C .

The blade holder and its various members cooperating with the pusher is particularly detailed in figure 3 where are represented the driving abutment 6, the pin 14 of attachment of the spring element 4 and the pin 12 sliding in the groove 13 of the pusher and forming axis of rotation of the blade holder relative to the pusher.

To avoid unwanted disengagement of the drive abutments 5, 6 and allow the blade holder to retract relative to the pusher and the reengagement of drive stops, the first spring element 4 clings 14, 15 to the pusher and to the blade holder in one direction so as to apply to the blade holder a torque in a direction opposite to the disengagement of the first and second stops 5, 6.

According to the example, the spring element 4 clings to the pins 14 of the blade holder 2 and the pin 15 of the pusher 3 in a direction slightly inclined relative to the groove 13 of the pusher, the pin 15 on the pusher being further away the axis of the groove 13 that the pin 15 so that the spring element applies to the blade holder a torque resistant to the rotation of the blade holder in the direction of disengagement of the first and second stops 5, 6 and brings back the stop drive 6 of the blade holder against the ramp 8 during the retraction of the pusher to re-engage the drive stops.

In addition, the first spring element 4 is positioned relative to the pin 12 and the finger 9 so as to apply to the blade holder a torque around the pin 12 tending, blade holder positioned in the inclined cutting position, to release the finger 9 of the shoulder 10.

To do this and according to the example shown in figure 1 , the pin 14 of attachment of the spring element is disposed in front and below the pin 12 forming the axis of rotation of the blade holder 2 while the finger 9 is located in front of the pin 14 and above the pin 12 .

The invention also applies to a safety knife as represented here by way of example for which the pusher is made in the form of a sliding drawer operated by an operating member protruding outside the body 11a, 11 b of the knife.

According to the example shown in Figures 1 to 4 , the operating member 16 is formed as a rotary trigger returned to the rest position, that is to say in the position for which the blade holder and the pusher are retracted into the body of the knife, by a second element spring 22 whose one end is fixed on a pin 23 of the trigger and the other end is fixed on a pin 24 made on one of the half-shells of the knife.

As more particularly represented in figure 2 , the rotary trigger 16 comprises an axis of rotation 27 received in bores 28 made in the half-shells. It comprises a bearing surface 29, for the palm of the operator, which protrudes half-shells 11a, 11b by a slot made in the latter.

It is connected to the pusher through a lever 17 having a thrust end provided with a second axis 17a engaging in a slide 18 of the pusher, as shown in FIG. Figure 4B especially where the trigger has been removed to better represent the connection of the lever 17 with the pusher 3, and a drive end provided with a third axis 17b received in a slot 19 of the trigger as shown in FIG. figures 2 and 4A especially.

The lever which has an axis of rotation 17C in the form of a bore, more particularly visible in figure 1 , receiving a 17D axis made in one of the half-shells of the knife body and visible in figure 2 , converts the rotational movement of the trigger into a translational movement of the pusher and amplifies the relatively limited rotational stroke of the trigger to obtain a large translational stroke of the pusher.

The slide 18 of the pusher and the oblong slot 19 of the trigger allow a compact assembly for which the pusher and the trigger are side by side.

The knife according to the example shown in Figure 4A further comprises means for locking the trigger in the form of a latch 30 and interfering with a tooth 32 of the trigger, the latch being removed from the interference position with the tooth 32 under the action of a push button 31 connected to the lock by a spring link 33 pivoting the lock when pressing the push button 31.

In a variant represented at figure 5 , the knife body 11a comprises a travel limiter of the blade holder formed according to the example by a return 34 of a rim 35 of the knife body.

This stroke limiter 34, arranged on a side opposite to the side of the blade holder carrying the finger 9, stops the blade holder and prevents it being pulled outwards during cutting.

Thus the movement of the blade holder relative to the pusher is limited to the front.

The invention is not limited to the example shown and is particularly applicable to a safety knife for which the actuating member may be an actuating button secured to the pusher protruding from the knife body through a slot made in at least one of the half-shells 11a, 11b.

Claims (10)

1. Safety knife (1) with a device for automatic blade retraction after cutting, comprising a blade holder (2) and a pusher (3) for operating the blade holder that slides longitudinally in the body of the knife in order to allow the blade carried by the blade carrier to exit from the body of the knife, characterized in that the blade holder and the operating pusher are connected by a first spring element (4) applying a first drive stop (5), which is a part of the pusher, against a second drive stop (6) of the blade carrier, said first and second stops (5, 6) being designed to disengage by rotation of the blade holder with respect to the pusher under a cutting force (E), and characterized in that the blade holder (2) has a finger (9) designed to bear against a shoulder (10) of the knife body (11a, 11b) and to retain the blade holder (2) in an inclined cutting position with respect to the operating pusher (3).
2. Safety knife according to Claim 1, in which the second drive stop (6) is received in a window (7) of the pusher forming a cam path defining an advanced position and a retreated position of the blade holder with respect to the pusher, the first drive stop (5) being constituted by a stop of a ramp (8) formed in the cam path (7).
3. Safety knife according to Claim 1 or 2, in which the blade holder (2) has a stud (12) sliding in a longitudinal groove (13) of the pusher and forming an axis of rotation of the blade holder with respect to the pusher.
4. Safety knife according to Claim 3, in which the first spring element (4) is attached (14, 15) to the pusher (3) and to the blade holder (2) in a direction so as to apply to the blade holder a torque in a direction opposed to the disengagement of the first and second stops (5, 6).
5. Safety knife according to Claim 4, in which the first spring element (4) is positioned with respect to the stud (12) and to the finger (9) so as to apply to the blade holder a torque about the stud (12) tending, with the blade holder positioned in the inclined cutting position, to disengage the finger (9) from the shoulder (10).
6. Safety knife according to one of the preceding claims, in which the pusher is produced in the form of a slide operated by an operating member (16) projecting outside the body (11a, 11b) of the knife.
7. Safety knife according to Claim 6, in which the operating member (16) is produced in the form of a rotary trigger returned to the rest position by a second spring element (22).
8. Safety knife according to Claim 7, in which the rotary trigger is connected to the pusher via a lever (17) having a thrust end provided with a second pin (17a) engaging in a slideway (18) of the pusher and a drive end provided with a third pin (17b) received in a slot (19) of the trigger.
9. Safety knife according to one of the preceding claims, in which the blade holder has a first rear stop (20) cooperating with a second rear stop (21a, 21b) borne by the body of the knife in order to stop the retreating movement of the blade holder disengaged from the pusher, the pusher being designed to retreat into the body under the action of the first spring element in a position of reengagement of the drive stops (5, 6) of the blade holder and of the pusher.
10. Safety knife according to one of the preceding claims, in which the knife body (11a) comprises a blade holder travel limiter.

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