EP1674219B1 - Knife - Google Patents

Abstract

The knife has a knife housing in which a blade carrier (14) accommodating a knife blade (16) is guided, and an operating part (24) movable relative to the carrier. A motion converter is arranged between the part and the carrier and initiates an additional relative movement between the carrier and the part with a force acting transverse to a knife edge, where the movement separates a primary coupling unit from a secondary coupling unit.

Description

The invention relates to a knife according to the preamble of claim 1. Such a knife is in the DE 102 08 345 C1 described.

The well-known knife according to the DE 102 08 345 C1 makes use of the peculiarity that the cutting reaction force occurring during the cutting process between the knife blade and the material to be cut contains a pulling force component which causes its additional relative movement in the extension direction of the blade carrier. This additional relative movement is used to disengage the motion clutch between the blade carrier actuating member and the blade carrier.

By the separation of the movement clutch between the actuating part and blade carrier, a protective reaction can be triggered, which may for example consist of a protective element, e.g. a protective pin, the knife edge over locking. In particular, the protective reaction may consist in that the blade carrier receiving the knife blade immediately returns to its protective position within the blade housing when the contact with the material to be cut is lost. The latter regardless of whether the operating member for the blade carrier is manually held in the extension direction or not.

In a knife according to the DE 197 23 279 C1 , which is a precursor of the knife according to the DE 102 08 345 C1 represents, the pulling portion of the cutting reaction force, which causes the additional relative movement between blade carrier and blade housing, the inclination angle of the knife edge relative to the material to be cut depends. at At low angles, the pulling portion of the cutting reaction force is relatively high, at larger angles it is smaller and at an angle of 90 °, so if the cutting reaction force is perpendicular to the blade edge, the fraction is zero.

Only with a knife inserted obliquely to the cutting material according to DE 197 23 279 C1 Accordingly, the pulling portion of the cutting reaction force is so large that the blade carrier pulled out of the blade housing and thus triggered the safety mechanism, ie the motion clutch between the actuating member for the blade carrier and the blade carrier is canceled.

The generic safety knife according to the initially described DE 102 08 345 C1 differs from the knife according to the DE 197 23 279 C1 in that the front area of the blade carrier receiving the knife blade together with the knife housing forms a motion converter which initiates the additional relative movement by a pressure force acting perpendicularly on the edge of the knife blade within a transverse play present between blade carrier and knife housing a component of movement of the blade carrier perpendicular to the cutting edge , connected to a movement component in the extension direction of the blade carrier causes.

The above-described embodiment gives the knife according to the DE 102 08 345 C1 an additional advantageous security, since the safety mechanism is already triggered when the cutting reaction force is in the range of pure compressive force, so if the cutting edge of the knife blade is perpendicular to the cutting material.

At the knife according to the DE 102 08 345 C1 Therefore, the required relative to the triggering of the safety mechanism additional relative movement regardless of the angle of inclination that exists between the cutting edge of the knife blade and the cutting material.

Starting from the per se advantageous knife according to the DE 102 08 345 C1 , This invention has for its object to further develop the safety mechanism further.

This object is achieved together with the features of the preamble of claim 1 according to the invention in that the motion converter and the transverse play between the blade carrier and the actuating part are formed.

In the safety knife according to the DE 102 08 345 C1 the actuator must abut against a front limit stop, so that the protective reaction triggering additional relative movement between the actuator and the blade carrier - regardless of the inclination angle between the knife edge and Schneidgut - can ever arise.

In the knife according to the invention, however, the actuating member does not need to first encounter against a limit stop, but the additional relative movement arises at each feed position or intermediate position of the blade carrier, as soon as a force acts on the knife edge. This happens even if the cutting reaction force is in the range of pure compressive force, so if the cutting edge of the knife blade is perpendicular to the cutting material.

This advantage according to the invention is achieved in that the motion converter in each intermediate position of the blade carrier, ie at each extension length of the knife blade, can be activated by a pressure on the knife edge to the additional required for the protective effect To generate relative movement, by which the primary coupling element and the secondary coupling element are separated from each other.

In a preferred application, this has the consequence that the knife blade returns to its protective position within the blade housing.

Another consequence may be that, by separating the primary coupling element from the secondary coupling element, a protective part, such as e.g. a spring-loaded protection pin, is activated, so extends and, the knife edge across, prevents unpleasant cuts.

According to an advantageous embodiment of the invention, the motion converter is formed by a formed by the blade carrier or by the operating part, inclined to the central axis of the blade housing oblique sliding plane and formed by an actuating part or the blade carrier, cooperating with the inclined sliding plane sliding edge.

In particular, the following features are essential to the invention:

In a knife with a knife blade receiving a blade carrier and a movable relative to the blade carrier actuating part between the actuating part and the blade carrier a motion converter is arranged, which initiates an additional relative movement between blade carrier and actuating part in a transversely acting on the knife edge of the knife blade pressure, which is independent from the feed position of the motion-coupled with the actuating part in the extension direction blade carrier. The additional relative movement triggers a separation between two actuating member and the blade carrier only in the extension direction with each other coupling-coupling elements.

In the drawings, a preferred embodiment according to the invention is shown, in which Figs. 1-6 show the functional sequence of a safety knife on the basis of schematic representations, while Fig. 4A in the form of an enlarged drawing details one of the functional representation of FIG. 4 basically analogous embodiment reproduces.

In the knife 10 shown in the drawings, a safety knife, only a housing shell 12 of a blade housing 11 is shown.

Within a longitudinal recess 13 of the housing shell 12, a blade carrier designated as a whole by 14 can be displaced translationally in a straight line along the center axis designated M, specifically in the extension direction x and in the withdrawal direction z.

The front portion 15 of the blade carrier 14 receives a made of steel strip knife blade 16, which has a trapezoidal shape in the present case. The knife edge of the knife blade 16 is denoted by 17.

A portion of the front portion 15 of the blade carrier 14 is shown broken away to make other components of the blade 10 visible. At the front region 15 of the blade carrier 14, a guide extension 18, which has a longitudinal recess 19 for receiving a tension spring 20, adjoins in the rearward or retreat direction z. The front spring eye 21 of the tension spring 20 is held at an attachment point of the blade carrier 14 and the rear spring eye 22 at an attachment point of the housing shell 12. The tension spring 20 attempts to pull the blade carrier 14 in the withdrawal direction z into the blade housing 11.

At the front portion 15 of the blade carrier 14, a laterally projecting sliding projection GV is present, which forms a sliding plane GE, which encloses an acute angle β together with the extension direction x.

Within the longitudinal recess 13, an actuating part 24 is also arranged, which is also guided in the longitudinal recess 13 in the extension direction x and in the retraction direction z.

The actuating member 24 has a rear portion 25, which is followed by a control extension 26 with a front sliding edge GK.

A tension spring 27 is held with its front spring eye 28 on the actuating part 24 and with its rear spring eye 29 on the housing shell 12. The tension spring 27 thus tries to move the operating part 24 in the withdrawal direction z.

Blade carrier 14 and actuating part 24 are guided, including a transverse play Q in two mutually parallel trajectories.

Also disposed in the longitudinal recess 13 and the rear portion 25 of the actuating member 24 is an approximately T-shaped member 30, which consists of a total of a resilient material, in particular spring steel. The stem 31 of the T-shaped component 30 is clamped in the rear region 25 of the actuating part 24 in a clamping point 40. The pointing away from the rear portion 25 of the actuator 24 end of the handle 31 forms with the rod 32 a representative bar of the T-shaped member 30 has a rigid connection node 42. The rigid connection node 42 in the extension direction x facing longer portion of the rod 32 provides a coupling 33rd The rearwardly in the retraction direction z-facing region of the rod 32 forms a control arm 34 which cooperates with a control surface SF of a control cam 35 which is formed on the housing shell 12.

The control surface SF according to FIGS. 1-4 and according to FIGS. 5 and 6 represents a sliding guide surface for the coupling arm 34, which encloses an acute angle α with the retraction direction z.

The front end of the coupling arm 33 forms a primary coupling element P, while a rearwardly in the retraction direction z open coupling opening (recess) of the blade carrier 14 is a secondary coupling element S.

The rod 32 thus represents a two-armed lever which on one side of a lever joint formed by the handle 31 with its primary coupling element P in the extension x to the facing coupling arm 33 and on the other side of the lever joint point the backward in the retraction direction z facing control arm 34th forms.

The control arm 34 is contactable by means of the control surface SF, while the actuating member 24 is in its withdrawn in the withdrawal direction z position. In this case, the rod 32 is pivoted such that the primary coupling element P moves from a position located outside the movement path of the secondary coupling element S release position into a standby position for engagement in the secondary coupling element S.

The function of the knife 10 is as follows:

According to Fig. 1, the knife 10 is at rest. The tension spring 27 pulls the actuating member 24 with its rear end face 36 against a stop surface 37 of the housing shell 12. In this case, the primary coupling element P is still at a small distance (in the standby position) in front of the secondary coupling element S.

According to FIG. 2, a manual force H has already been exerted in the extension direction x to such an extent via an actuating projection 38 that the control arm 34 is already out of contact with the control surface SF. With the beginning of the extension movement in direction z, the primary coupling element P was previously immersed in the secondary coupling element S, while the control arm 34 still abutted on the control surface SF due to the resilient design of the T-shaped component 30. In this case, the primary coupling element P remained aligned with the secondary coupling element S.

The manual force H, which continues to act in the extension direction x, subsequently causes the control arm 34 to move farther away from the control surface SF, so that according to FIG. 3 the knife blade 16 passes freely outwardly through the outlet gap 23 of the blade housing 11.

2 and 3, it should be noted that the sliding edge GK of the control extension 26 is located over the entire feed path in the direction x of FIG. 2 in FIG. 3 in the lower region of the sliding plane GE of the sliding projection GV. With reference to FIG. 3, it can also be stated that the blade carrier 14, together with the knife blade 16, has not yet been fully extended.

Then, as shown in Fig. 3, a compressive force D begins, e.g. acting perpendicular to the knife edge 17 of the knife blade 16, the blade carrier 14, when comparing Fig. 3 and Fig. 4, with each other, as shown in FIG. 4 with its sliding plane E along the sliding edge GK to the transverse clearance Q down and puts it at the same time an additional relative movement with a return amount R back. In this case, the coupling between the elements P and S is separated, while the feed position in the direction x of the operating part 24 has not changed.

After this representation of the functional sequence of Fig. 1 of FIG. 4 it is clear that the passing through the sliding plane GE and by the sliding edge GK formed motion transducers GE / GK regardless of the feed or intake situation in the direction x or in the direction z can always be effective as soon as a compressive force D occurs, which of course can also be directed to the knife edge 17 inclined.

It is now assumed that the cutter 10 is continued according to the functional representation of FIG. 4, until the knife blade 16 exits the cutting material, the knife blade 16 is no longer held in the product to be cut and the spring 20 retracts the blade carrier 14 and Thus, the functional state of FIG. 5 is reached. Thereafter, the knife edge 17 of the knife blade 16 is slid from a cutting material, not shown, so that the tension spring 20 could be effective and has put the blade carrier 14 together with the knife blade 16 received by him in the withdrawal direction z in a protective position in the knife housing 11 inside.

It is also conceivable that in an embodiment not shown, as a result of the separation of the coupling between the elements P and S, the blade carrier 14 together with the knife blade 16 would not retract into the knife housing 11 in the withdrawal direction z. Rather, alternatively, the potential energy of tensioned in the direction of tension spring 20 20 could also be used to extend a protective device, such as a known per se protection pin, parallel to the central axis M along the knife edge 17 to prevent cuts.

In connection with FIG. 5, it should be noted that the manual force H acts unchanged and that the actuating part 24 is thus held in its x direction forward position.

If now the manual force H enNällt, first the situation arises according to FIG. 6, after which the sliding edge GK has again reached the lower region of the sliding plane GE. The rear end face 36 of the operating part 24th Also located is the primary coupling element P just below the secondary coupling element S, while the end of the control arm 34 of the T-shaped member 30 already touches the control surface SF of the control cam 35. This means that the control arm 34 starts against an axial spring restoring force during its movement in the retraction direction z, while the coupling arm 33, which also moves in the retraction direction z, passes the secondary coupling element S with its primary coupling element P.

In the transition from the functional representation of FIG. 6 back to FIG. 1, the tension spring 27 is fully effective by the rear end face 36 of the actuating member 24 moves against the cutter housing side stop surface 37. At the same time, the control arm 34 of the T-shaped component 30 is increasingly pressed against the control surface SF of the control cam 35 while the T-shaped member 30 progressively bent so that the coupling arm 33 of the rod 32 abuts the lower longitudinal edge 39 Führungsfortsatzes 18 and thereby the primary coupling element P is placed in a standby position with a small distance in front of the secondary coupling element S.

With regard to the functional sequence, FIG. 4A basically corresponds to FIG. 4. However, the rod 32 is designed differently according to FIG. 4A, since it consists of an integral, rigidly interconnected, rigidly connected part, which forms an approximately Z-shape namely, a rigid coupling arm 33, a middle rigid connection region 44 angled relative to the latter, and a rigid control arm 34 connected to the connection region 44.

The middle connection region 44 is mounted by means of a pivot joint G in the rear region of the operating part 24. The the primary coupling element P forming coupling arm 33 is held by a tension spring 41 against a schematically illustrated support A down. Otherwise, the following to the functional representation of FIG. 4A subsequent functions corresponding to FIGS. 5 and 6 and back to Fig. 1 in an analogous manner.

The embodiment according to FIG. 4A has the advantage that, because of the rigid design of the rod 32, greater forces can be transmitted in the direction x to the blade carrier 14 via the actuating member 24, as is the case, for example, with a jerky insertion of the knife blade 16 into a solid cardboard material occur.

In any case, the T-shaped component 30 according to FIGS. 1-6 and the rigid rod 32 according to FIG. 4A each form a two-armed lever in the broadest sense, comprising a lever arm 33 (coupling arm) and a lever arm 34 (control arm). In this case, the joint point is formed either by the flexible stem 31 above its clamping point 40 (FIGS. 1-6) or by a pivot joint G (FIG. 4A).

A special feature of the embodiment according to FIG. 4A is that the control arm 34 accommodates a spring plunger 43 which is movable along the two axial directions x and z and which, with the spring travel AF, is flush with the rear end face 37 of the rear region 25, counter to the restoring force F of a buffer spring 45 in the latter is insertable.

With the above-described embodiment according to FIG. 4A, the following function is combined:

After the knife edge 17 of the knife blade 16 has lost its contact with the material to be cut at the end of the cutting work, the tension spring 20 pulls the blade carrier 14 back into its retracted position, as is apparent from the functional sequence corresponding to FIGS. 5 and 6. The Tension springs 20 and 27 are not registered because of a simplification of the drawing in Fig. 4A, but are, as shown in Figs. 1-6, nevertheless present.

Just before the operating member 24 shown in Fig. 4A (see Fig. 6) reaches its retracted position (see Fig. 1) in which the rear end face 36 of the operating member 24 abuts against the housing-side abutment surface 37, the free end of the Spring plunger 43 against the housing-side stop surface 37 at.

In this case, the primary coupling point P forming coupling arm 33 is pivoted upwardly against the guide extension 18 of the blade carrier 14 and finally arranged in the control arm 34 buffer spring 45 so far compressed until the spring plunger 43 entirely in the control arm 34 and at the same time in the rear portion 25 of the operating part 24 disappears. During this retraction stroke of the spring tappet 43, the coupling arm 33, which likewise moves in the retraction direction z, passes over with its primary coupling element P the secondary coupling element S. The coupling arm 33 is held in an upwardly directed pivoting position.

At the beginning of a renewed extension movement of the operating part 24 in the direction x, the buffer spring 45 expands slightly again. In this case, the spring plunger 43 exits to a certain extent from the control arm 34 and from the rear region 25 of the actuating part 24, with the result that the primary coupling element P from its standby position (see Fig. 1) from in the direction x in the secondary coupling element S engages (see Fig. 2), while the spring pin 43, the coupling arm 33 still holds in its upper pivot position.

From the above description it is clear that in the embodiment of FIG. 4A, the housing-side stop surface 37 at the same time forms the control surface SF.

Claims (2)

1. Knife (10) with a knife housing (11) in which a blade carrier (14) receiving a knife blade (16) is guided in a relatively movable manner, which blade carrier may be moved by means of an actuating part (24) counter to a restoring force from a protected, retracted starting position of the knife blade (16) in the knife housing (11), into a cutting position of the knife blade (16) projecting from the knife housing (11), the actuating part (24) being movable relative to the blade carrier (14) and, in particular, being loaded by a separate restoring force (27) counter to the extension movement (at x) of the blade carrier (14), the blade carrier (14) and the actuating part (24) being coupled in their starting position by a primary coupling element (P) of the actuating part (24) or the blade carrier and by a corresponding secondary coupling element (S) of the blade carrier (14) or the actuating part such that they only move together in the direction of extension (at x) of the blade carrier (14), but are not in engagement with one another in the direction of retraction (at z) of the blade carrier (14), the blade carrier (14) being able to carry out an additional relative movement (at R) in the direction of extension (x), which disengages the two coupling elements (P, S) from one another, and a motion converter (GE/GK) being associated with the blade carrier (14) which initiates the additional relative movement (at R), by a compressive force (D) acting transversely on the cutting edge (17) of the knife blade (16) within transverse play (Q) associated with the blade carrier (14) producing a component of motion of the blade carrier (14) transversely to the cutting edge (17), associated with a component of motion in the direction of extension (x) of the blade carrier (14), characterised in that the motion converter (GE/GK) and the transverse play (Q) are formed between the blade carrier (14) and the actuating part (24).
2. Knife according to Claim 1, characterised in that the motion converter (GE/GK) is formed by an oblique sliding plane (GE) formed by the blade carrier (14) or by the actuating part (24), inclined towards the centre axis (M) of the knife housing (11) and by a sliding edge (GK) formed by the actuating part (24) or by the blade carrier (14), cooperating with the oblique sliding plane (GE).

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