EP0452668A1 - Hand shears with ratchet mechanism for cutting bar shaped materials - Google Patents

Abstract

In hand shears for cutting bar-shaped materials, having two two-armed shear halves articulated on one another, one of which possesses a toothed quadrant (6) and a fixed grip (4), and the other possesses a short arm (8) on which a two-armed shearing grip (10) is articulated, a ratchet mechanism being additionally provided, it is proposed, in order to simplify operation, that the ratchet mechanism engages automatically when a cutting moment of given size is produced and disengages again upon closure of the shears. Mounted at the free end of the shearing-grip arm (11) facing the shear joint (3) is a supporting lever (15). The latter is released in the closed position of the shears and brought into a rest position by means of a spring arrangement (19), the direction of action of which reverses in the closed position of the shears. A detent lever, which cooperates with the toothed quadrant (6) and likewise is released in the closed position, in particular in cooperation with the supporting lever, and engages in the toothed quadrant again like the supporting lever as a function of the cutting moment, can additionally be articulated on the short arm (8). <IMAGE>

Description

The invention relates to a hand-operated scissors according to the preamble of claim 1. A strand-like clippings are preferably to be understood as branches, cables, steel cables, profiles or the like.

With simple scissors, the handles are firmly connected to the respective cutting edges or directly coupled via stops. These simple scissors offer a quick cut, but fail when higher cutting forces are required.

On the other hand, scissors with pawl mechanisms in a wide variety of designs are known, which bring about an additional power transmission. With these scissors with special translation arrangements, a significantly higher cutting force is obtained, but a lower working speed, since the handles have to be opened and closed several times in order to carry out a single cut.

A pair of scissors of the type described in the introduction is known from US Pat. No. 3,885,309. It can optionally be used in both drive types. The special drive mechanism with power transmission used in this known scissors is referred to below as a ratchet drive. In contrast to the firm grip of one half of the scissors, the so-called push handle is articulated on a short arm of the other half of the scissors and is supported in the closing direction by a stop. Thus, the scissors can be operated in a simple direct drive. On the other hand, the push handle contains a longitudinally displaceable bolt which is supported on the dental arch with a chisel-like cutting edge when released under spring force. A locking lever is also mounted on the short arm, which prevents the scissors from opening when the push handle is opened and the bolt cutting edge is pushed over a few teeth. After the cutting process, when the scissors are closed, the support bolt must be pulled back and locked by hand. As a result, the locking lever is also released via a ramp and a plunger, so that the scissors can now be opened. On the other hand, in order to switch the ratchet drive on again during the cutting process or at the beginning thereof, the plunger must be unlocked again, which also requires a separate handle.

The invention has for its object to propose a hand-operated scissors, which has a direct drive and a ratchet drive, but with which you can work much faster and easier.

This object is achieved in a generic hand-operated scissors according to the invention in that the ratchet drive when a Automatically switches on the cutting torque of a certain size and switches it off again when the scissors are closed. In order to make a cut, the scissors are first driven directly until the cutting jaws are closed so far at idle speed that they clamp the cut material or have penetrated it so far that the actuating force has reached a certain limit value. From now on the ratchet transmission works and the cutting process is completed by a pumping movement of the push handle. When the cutting jaws have reached their closed position, ie the scissors are closed as a whole and the push handle is then opened again for the first time, the drive arrangement goes back to direct coupling and the scissors can be opened quickly. So there are no additional handles while maintaining the advantages of the different drive types for the different cutting force requirements.

A preferred embodiment of the invention is characterized in that a support lever which can be latched into the dental arch is mounted at the free end of the push handle arm. Like the displaceable mandrel of the aforementioned US patent, this compensates for the distance, which changes when the push handle is pivoted, between the end of the short push handle arm and the support point on the dental arch. However, the support lever has the advantage that it can be moved more easily and can be integrated into the entire switching mechanism. The shape of the push handle can be chosen independently. In addition, a support lever opens the possibility of turning the teeth of the dental arch towards the scissors-type pivot, in particular to attach it to the inner edge of a window which also contains the support lever, which results in a particularly compact construction.

With non-resilient clippings, e.g. B. wood, the scissor jaws have no tendency to open again on their own. In this case, a locking mechanism, which holds the cutting jaws in their previous angular position when opening the push handle for repositioning the ratchet, is not necessary. As a particularly simple design, particularly suitable for one-handed scissors, it is proposed that the support lever be released in the closed position of the scissors and brought into a rest position. In particular, a spring arrangement acting on the support lever can be provided, the direction of action of which is reversed in the closed position of the scissors. A particularly suitable spring arrangement has been found to be an arc spring which comes into contact with the other half of the scissors in the closed position and thereby deforms in the desired sense. However, two counter-acting single springs can also be provided, one of which is blocked in the closed position. Other options for automatically releasing the support lever are addressed below.

In order to latch the support lever in dependence on the closing force, it is expediently provided that a spring element, in particular a block-shaped body made of an elastomer, is provided between the short arm and the push handle, which urges the push handle in the opening direction away from the stop on the short arm and a holding force exerts a holding means that holds the support lever in its rest position. The holding means can be two hooks or surfaces adhering to one another by friction. According to this idea, the force of the spring element or the moment it exerts on the push handle is decisive for how high the closing torque must be in order to release the support lever.

An expedient practical configuration consists in that the support lever in the notched position engages behind a retaining edge arranged on the short arm and thereby blocks the opening movement of the push handle with respect to the short arm under the action of the spring member. If the push handle is pivoted with respect to the short arm when the closing force increases while the spring mechanism is pressed together, the support lever is no longer loaded, so that the friction effect on the nose is eliminated and the support lever engages in the dental arch under the action of its spring.

In the case of resilient clippings, as is known per se, a latching lever articulated on the short lever is required, which remains latched in when the support lever is adjusted. In the sense of an automatic release of this locking lever in the closed position of the scissors, it is proposed that a spring arrangement acting on the locking lever is provided, the direction of action of which is reversed in accordance with the spring arrangement mentioned above in the closed position of the scissors.

In addition, the locking lever can participate in switching the support lever on and off. In principle, this can be done in such a way that the latching lever, in its unlatched position, blocks the opening movement of the push handle with respect to the short arm under the action of the spring mechanism, is held in the unlatched position even by the action of friction or interlocking and causes the support lever to disengage.

It is advantageous for. B. when the locking lever is supported directly on the short push handle arm, that is, falls into its range of motion and is then held by the spring-back push handle arm by friction or positive locking (hooking). In this case, a spring element that yields in two directions can be used for the support lever be provided, which holds the support lever in its neutral position in an angular position in which it is released, as long as the push handle is in its locked position with the locking lever. The arrangement is such that when the push handle is opened, the support lever swings into the dental arch.

Another preferred possibility of interaction between the latching and support levers is that the latching lever is supported on the support lever and disengages the support lever against the force of a tension spring acting on it, the support lever engaging in the notched position on a stop of the push handle arm. In this case, if the cutting torque limit is exceeded, both levers snap into the dental arch immediately under the action of their own springs.

Occasionally there is a need to reopen the scissors during the ratcheting operation. It is therefore useful to provide an actuator to reverse the direction of action of the spring member acting on the latching or support lever by hand as required. For this, e.g. B. an eccentric, slide or the like. Provided that causes the same as otherwise the system on the other half of the scissors in the closed position.

The invention is independent of the shape and arrangement of the cutting jaws selected in the individual case. These can overlap scissor jaws or an anvil jaws can be involved. The jaws can be arranged laterally in the manner of a vulture's beak scissors and it is also possible to pivot a cutting jaw on one scissor half and to guide it in a slot guide in the other scissor half. The The drive arrangements described are also particularly suitable for shear designs with an extendable handle, so-called pruning shears. In these, the push handle is actuated by means of a cord, possibly via a pulley.

Fig. 1

eine einfache Einhandschere ohne Rasthebel in geschlossener Stellung, jedoch noch unter Betätigungskraft,

Fig. 2

eine Zweihandschere mit zusammenwirkendem Rast- und Stützhebel in der geschlossenen Stellung,

Fig. 3

die Schere nach Fig. 2 in geöffneter Stellung bei eingeschaltetem Ratschenantrieb,

Fig. 4

ein weiteres Beispiel einer Zweihandschere und

Fig. 5

die Schere nach Fig. 4 in geöffneter Stellung bei eingeschaltetem Ratschenantrieb.

Three embodiments of the invention are explained below with reference to the drawing, wherein the handles are shown broken off. In detail shows

Fig. 1

a simple one-hand scissors without locking lever in the closed position, but still under operating force,

Fig. 2

a pair of scissors with interacting locking and support lever in the closed position,

Fig. 3

2 in the open position with the ratchet drive switched on,

Fig. 4

another example of two-handed scissors and

Fig. 5

4 in the open position with the ratchet drive switched on.

1, the two scissor halves are articulated with their cutting jaws 1 and 2 by means of a hinge pin 3. The upper cutting jaw has a fixed grip 4 and, by means of a frame-like configuration, forms a window 5 with a tooth arch 6 which is concentric with the hinge pin 3 and whose teeth 7 are arranged on the window inner edge facing the hinge pin 3. The lower half of the scissors with the cutting jaw 2 has a plate-shaped short arm 8. A push handle 10 is attached to this by means of a bolt 9 mounted, which has a short push handle arm 11 facing the hinge pin 3. On the short arm 8 there is a stop 12 against which the push handle arm 11 comes to rest when the push handle 10 is closed, as a result of which this short scissor arm is coupled directly to the push handle 10. In the stop 12, a rubber block 13 is inserted which pushes the push handle arm 11 away from the stop 12, provided that the cutting torque is not so great that the rubber block 13 deforms elastically.

A support lever 15 is mounted on the push handle arm 11 by means of a bolt 13, which has support teeth 16 on one side and a nose 17 on the other side, which cooperates with a projection 18 of the stop 12.

To move the support lever 15, an arc spring 19 is provided from a spring band, which is held at one end in an internally cylindrically widening edge slot 20 of the push handle arm 11 and at the other end engages in an edge slot of the support lever 15. Finally, a tension spring 21 is also provided, which pulls the push handle 10 in the opening direction.

In the closed position of the scissors shown, the middle part of the bow spring 19 lies against the window edge of the upper half of the scissors. As a result of the deformation caused thereby, the spring tends to pivot the support lever 15 to the left. In the position shown, the push handle 10 is still loaded, so that the support lever 15 presses on the relevant teeth of the dental arch 6 and is held in place by friction. As soon as the push handle 10 is relieved, the support lever 15 moves and its nose 17 lies over the projection 18 and is now held in this position since the rubber block 13 wants to pivot the push handle arm 11 with respect to the short arm 8. The support lever 15 is thus loaded on train. The scissors thus open under the action of the tension spring 21.

By relieving the bow spring 19, it now has the tendency to pivot the support lever 15 to the right and latch into the dental arch 6. Due to the expansion force of the rubber block 13, the support lever 15 is held in the notched position, however, since the nose 17 rubs against the projection 18.

The cutting process proceeds as follows: starting from the last-mentioned open position, the push handle 10 is moved in the closing direction and takes the cutting jaw 2 with it in direct coupling. However, as soon as the moment of the push handle 10 with respect to the short arm 8 increases due to the mutual friction of the cutting jaws or the cutting pressure of the inserted material to be cut, a relative movement takes place with compression of the rubber block 13, with the result that the support lever 15 is released and into the Dental arch 6 engages. The ratchet drive is now switched on. If the push handle 10 is opened again, the support lever 15 jumps further by one or more teeth and, when the push handle is pressed again, the scissors are closed a little further under the action of a lever. This process can be repeated several times until the drawn closed position is reached or the cutting force is so low that it is possible to continue cutting in direct coupling. The aforementioned reversal of the direction of action of the arc spring 19 in this position releases the support lever 15 and remains released when the scissors are opened and until a certain cutting pressure is reached again.

In the exemplary embodiment according to FIGS. 2 and 3, the following basic elements are again found, which are identified by the same reference numbers as in the first exemplary embodiment: cutting jaws 1 'and 2', articulated bolt 3 ', fixed handle 4', short arm 8 ', bolt 9', Push handle 10 ', Push handle arm 11 ', stop 12', rubber block 13 ', bolt 14', support lever 15 '. The cutting jaw 2 'is not attached to the scissor arm here, but is pivotably mounted on the pin 23 and provided with an extension which is guided in a slot 24 of the other scissor arm. In comparison to the first exemplary embodiment, the stop 12 'is located on the opposite side of the bolt 9' and is designed as a bend in the plate-shaped short arm 8 '. The support lever 15 'has a different shape and is brought into engagement by a tension spring 25. In the unlatched position (Fig. 2) he lies against a stop pin 26 which is attached to the push handle arm 11 '. In comparison to the first exemplary embodiment, the dental arch 27 is oriented in the opposite direction and is designed as a tooth segment, the teeth of which protrude radially outward.

This example also shows a locking lever 28 which is mounted on the short arm 8 'by means of a bolt 29 and is actuated by an arc spring 30. This bow spring, which is clamped at one end between two pins 31 and at the other end engages in an edge slot of the locking lever 28, has a similar shape and the same function as the bow spring 19 of the first exemplary embodiment. A rotary member 32, which has an adjusting handle on the invisible rear side, has an upper section of semicircular cross section 33 corresponding to the height of the arc spring 30. By rotating it 90 ° to the right, the arc spring 30 is given freedom of movement until it lies against the flat surface of the rotary member, which also results in a reversal of the direction of action of the spring, ie the notching of the locking lever 28. In doing so, it abuts a stop pin 34 with its rear side. The locking lever 28 has on one side with the Dental arch 27 cooperating teeth 35 and on the other side a support nose 36 which cooperates with a nose 37 on the support lever 15 '.

To explain the mode of operation, the position of the support lever 15 ', the latching lever 28 and the push handle 10' according to FIG. 2 is first considered. The support lever 15 'abuts the stop pin 26 and its nose 37 rests on the nose 36 of the locking lever. The rubber block 13 'exerts a torque on the push handle 10' in the opening direction due to its expansion forces. This creates frictional forces on the two noses lying one on top of the other, so that the position shown is maintained even if, as a result of opening the scissors, the pressure of the tight grip on the bow spring 30 is eliminated and this thereby tends to latch the locking lever 28 to the left in the dental arch. The scissors can therefore be opened. Even if the jaws rub against each other relatively strongly, the lever configuration described is retained, since the opening force only increases the elastic force of the rubber block 13.

At the beginning of the closing movement of the scissors from the fully open position, nothing changes at first. However, as soon as the cutting jaws find resistance on the material to be cut 38, there is a slight pivoting movement of the push handle 10 'with respect to the short arm 8', that is to say the stop 12 ', against the expansion force of the rubber block 13'. This relieves the lugs 36 and 37 lying one on top of the other. The bow spring 30 can latch the latching lever 28. This also frees the support lever 15 'and, under the action of its tension spring 25, also clicks into the tooth arch 27. This is shown in Fig. 3.

When cutting with a ratchet drive according to FIG. 3, the support lever 15 'remains latched when the push handle 10' is closed, while the locking lever 28 ratchets over the teeth. On the other hand, when the push handle is opened, the locking lever remains latched in and the support lever continues. If the scissors are to be opened again when the cutting process has not yet been completed, the rotary member 32 is switched over, which leads to the latching lever 28 being released. When the push handle 10 'is opened, the lugs 36 and 37 of the two levers then lie on one another and the support lever 15' also disengages. While the described switchover to the direct drive is only to be regarded as a special case, the direction of action of the bow spring 30 is automatically reversed each time the scissors are closed, specifically as a result of the bow spring resting on the side face of the other half of the scissors.

The third exemplary embodiment of a pair of scissors according to FIGS. 4 and 5 is very similar to the second exemplary embodiment, if one disregards the different cutting jaws. Substantial parts which correspond in their function are identified by the reference numerals which have been used so far, but which are crossed out. These parts are the hinge pin 3 ", fixed handle 4", pin 9 "of the push handle 10", push handle arm 11 ", stop 12" and rubber block 13 ", support lever 15" and the locking lever 28 "with Bow spring 30 '' and support nose 36 ''. In this case, instead of a rotary member, a push pin 34 which can be displaced in a slot 39 is provided for the purpose of emergency opening of the scissors.

The main difference compared to the second embodiment is that the nose 36 '' of the locking lever not with the support lever, but with the Push handle arm 11 '' interacts directly. The support lever 15 'has a somewhat different shape with a rounded support lug corresponding to the rounded dental arch and is mounted without bolts in a circular edge recess in the push handle arm 11''. This support lever, which is held by means of a U-spring 41 on the push handle arm 11 ″, assumes its rest position according to FIG. 4. It does not come into contact with the dental arch by spring action, but rather in that it is pivoted towards the dental arch when the push handle 10 ″ is opened. The U-spring 41 allows the teeth to be skipped. The U-spring also yields elastically when the push handle 10 ″ is moved into the closed position during the ratchet drive and the support lever is held in the relevant dental arch due to the support pressure.

It can be seen that in this example, too, the mechanism for disengaging the support and locking lever in the closed position, the mechanism for holding the two levers in the unlatched position under the action of the rubber block 13 '' and the mechanism for disengaging the two levers increased cutting torque is the same as in the previous example.

Claims (14)

Manually operated scissors for cutting strand-like clippings with two hinged two-armed scissor halves, one of which has a dental arch and a fixed handle and the other has a short arm, on which a two-armed push handle is articulated and supported in the closing direction by a stop, with a ratchet drive in the It is provided that the push handle arm facing the scissor joint is able to support itself on the dental arch and thereby leverage is exerted on the short arm during the closing movement of the push handle, characterized in that the ratchet drive switches on automatically when a cutting torque of a certain size occurs and when the scissors close switches off again. Scissors according to claim 1, characterized in that a support lever (15) which can be latched into the dental arch (6; 27) is mounted at the free end of the push handle arm. Scissors according to claim 2, characterized in that the support lever (15) is released in the closed position of the scissors and brought into a rest position. Scissors according to claim 3, characterized in that a spring arrangement (19) acting on the support lever (15) is provided, the direction of action of which is reversed in the closed position of the scissors. Scissors according to claim 3, characterized in that a spring element is provided between the short arm (8) and the push handle (10), which urges the push handle away from the abovementioned stop (12) and exerts a holding force on holding means which the support lever (15 ) hold in its rest position. Scissors according to claim 5, characterized in that a block-shaped body (13) made of an elastomer is provided as the spring element. Scissors according to claim 5, characterized in that the support lever (15) in the notched position with a nose (17) engages behind a retaining edge arranged on the short arm and thereby the opening movement of the push handle (10) with respect to the short arm (8) under the action of the spring member (13) locks. Scissors according to claim 3, characterized in that a latching lever (28) cooperating with the dental arch (27) is articulated on the short arm (8) and that a spring arrangement (30) acting thereon is provided, the direction of action of which is in the closed position of the scissors reverses so that the locking lever (28) disengages. Scissors according to claim 8, characterized in that an actuator (32; 40) is provided in order to reverse the direction of action of the spring element when necessary even when the scissors are not closed. Scissors according to claim 4 or claim 8, characterized in that the spring arrangement is an arc spring which comes into contact with the other half of the scissors in the closed position. Scissors according to claim 8, characterized in that the latching lever (28) in its unlatched position blocks the opening movement of the push handle (10) with respect to the short arm (8) under the action of the spring element (13), even by friction or hooking in the unlatched position is held and the release of the support lever (15) brings about. Scissors according to claim 11, characterized in that the latching lever (28 '') is supported directly on the short push handle arm (11 '') and on the support lever (15 '') a spring element (41) which yields in two directions acts, the support lever (15 '') is arranged so that it is released when the push handle (10 '') is locked and the spring element (41) is in the neutral position and engages when the push handle is open. Scissors according to claim 11, characterized in that the latching lever (28) is supported on the support lever (15 ') and the support lever disengages against the force of a tension spring (25) acting thereon, the support lever (15') being disengaged in the Position on a stop (26) of the push handle arm. Scissors according to claim 1, characterized in that the teeth (7) of the dental arch (6) face the scissor joint pin (3).

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