Scissors for cutting metal strips

Abstract

Shears for cutting metal strips, comprising a shear head (48) with a first shear leg (34) and a second shear leg (42), which are pivotable relative to each other, wherein a cutting-bending device (64) with a cutting edge (86) and a force application area (90) for bending a workpiece area (102) is arranged on the first shear leg (34), and a support device (70) for the workpiece with an opening (76) into which the cutting-bending device (64) can be immersed is arranged on the second shear leg (42), characterized in that the cutting-bending device (64) is designed such that the force application area (90) only acts on a workpiece area (102) after a cut has been made on the workpiece area (102), and that with the shear head (48) fully open, a minimum distance between the support device (70) and the cutting edge (86) is present, which is finite,wherein the minimum distance is at least 0.5 mm, and that a contact surface (84a; 84b) for a workpiece is formed on the first scissor leg (34) and / or second scissor leg (42), which is oriented transversely to a support surface (82a; 82b) of the support device (70), and which is effective when the scissor head (48) is fully open.

Description

The invention relates to a pair of scissors for cutting metal strips, comprising a scissor head with a first scissor leg and a second scissor leg which are pivotable relative to each other, wherein a cutting-bending device with a cutting edge and a force application area for bending a workpiece area is arranged on the first scissor leg and a support device for the workpiece with an opening into which the cutting-bending device can be immersed is arranged on the second scissor leg. Thin metal strips (with a typical thickness of 1 mm to 2 mm) can generally be cut by hand, although this requires a great deal of force. US 812 645 A discloses a combined punching and cutting tool. US 4 894 913 A reveals a tape cutting tool. US Patent 4,177,664 discloses a tool for strip metal for partially cutting recesses from one edge side of the workpiece. The invention is based on the objective of providing scissors of the type mentioned above, by means of which a metal strip can be cut with reduced effort. This problem is solved according to the invention in the aforementioned scissors by the fact that the cutting-bending device is designed such that the force application area only acts on a workpiece area if a cut has previously been made on the workpiece area, that when the scissor head is opened to its maximum, there is a minimum distance between the support device and the cutting edge, which is finite, wherein the minimum distance is at least 0.5 mm, and that a contact surface for a workpiece is formed on the first scissor leg and / or second scissor leg, which is oriented transversely to a support surface of the support device, and which is effective when the scissor head is opened to its maximum. The geometric design of the cutting and bending device makes it possible to ensure that when cutting a workpiece, the cutting action precedes a deflection of the workpiece in the same area of ​​the workpiece due to the force application area of ​​the cutting and bending device; that is, the force application area only acts on an area that has already been cut. This reduces the stress during cutting and workpiece deformation, thus decreasing the force required for cutting. This makes it easy to cut metal strips. For example, it has been shown that metal strips with a width of 32 mm and a thickness between 1 mm and 1.2 mm can be easily cut with scissors according to the invention. In the solution according to the invention, the separation (cutting) and deformation of a specific workpiece area do not occur simultaneously, but rather at different times. As a result, no bending work is required for a specific workpiece area when the cut is made. It is advantageous if the force-applying area is located directly next to the cutting edge. This allows for a simple geometric alignment between the cutting edge and the force-applying area, enabling force-minimized cutting of a metal strip. It is advantageous if the load-bearing surface of the force-bearing area is curved or inclined in a first direction and also inclined or curved in a second direction (which is linearly independent of the first direction). This allows the formation of a force-bearing area that "lags" during the cutting process, so that no bending work is required in a specific area of ​​the workpiece where the cut is made. In particular, the force-bearing area is formed by an underside region of the first scissor leg. For example, the force-bearing area is formed integrally with the cutting edge from a metallic material, and in particular from investment casting material. In one embodiment, the support device is U-shaped. This provides support surfaces for a workpiece, which are arranged next to the opening. The stability of the support device can be increased by a bridge element between the corresponding support elements on which the support surfaces are formed. In particular, the support device has a wall that defines the opening, against which the cutting edge is guided. A shearing action is performed against this wall to create the cut. With the shear head fully open, there is a minimum, finite distance between the support and the cutting edge. This ensures that when the cutting edge first impacts a workpiece as the first shear head pivots towards the second, the force is not immediately applied to the workpiece, but rather that deformation work occurs after the cut is made. The minimum distance is at least 0.5 mm and, for example, on the order of 1 mm. A contact surface for a workpiece is formed on the first and / or second scissor arm. This surface is oriented perpendicular to a support surface of the support device and is effective when the scissor head is fully open. This allows a workpiece to be inserted into the scissor head up to this contact surface when the scissor head is fully open. This, in turn, ensures that bending work is not immediately introduced into the initial section of the workpiece at the start of a cutting process, but rather that the deformation lags behind the initial cut. It is particularly advantageous if an elastic hold-down device for a workpiece is arranged on the first scissor arm and can be supported by the support device. The hold-down device ensures that, during cutting, a portion of the workpiece not directly affected by the cutting and bending unit is pressed against the support device to prevent it from snapping upwards. The hold-down device presses the workpiece against the support device, thus indirectly supporting itself against it. Its elastic design ensures that this pressure is maintained at every stage of the cutting process, even with varying depths of penetration of the cutting and bending unit into the opening. It is generally possible for the elastic hold-down device to include one or more spring elements in order to achieve elastic support. In a structurally simple embodiment, the hold-down device includes an elastic pad. This elastic pad is made, for example, of a polymer material. This allows for support over a relatively large area, both directly on the workpiece and indirectly on the support device. For example, the pad has a concave side facing the support device. It is also possible for the elastic pad to be replaceable. In one embodiment, the scissors comprise a holding device with a first handle and a second handle, which are pivotally connected to each other, wherein the first scissor arm is pivotally connected to the first handle and the second scissor arm is pivotally connected to the second handle. By moving the second handle towards the first handle, the first scissor arm can then be moved towards the second scissor arm, thereby performing a cutting and bending operation. It is advantageous if the holding device includes a spring mechanism that is arranged and designed such that a force against the spring force of the spring mechanism is required to pivot the second handle onto the first handle. To perform a cutting operation, a force must be exerted to pivot the first scissor arm onto the second scissor arm. The spring force then pushes the first and second scissor arms apart again. The following description of preferred embodiments, in conjunction with the drawings, serves to further explain the invention. The drawings show: Fig. 1 a top view of an embodiment of scissors according to the invention from a first direction; Fig. 2 a top view of the scissors according to Fig. 1 from the opposite direction; Fig. 3 an exploded view of the scissors according to Fig. 1; Fig. 4 an enlarged view of a scissor head of the scissors according to Fig. 1 during a cutting operation; Fig. 5 a sectional view along line 5-5 according to Fig. 4 during a cutting operation; Fig. 6 a sectional view along line 6-6; Fig. 7 a sectional view along line 7-7. An embodiment of a pair of scissors according to the invention, shown in Figs. 1, 2, 3, 4, 5, 6 to 7 and designated there by 10, is a pair of hand scissors. These include a holding device 12 by means of which the scissors 10 can be held and operated with one hand. The holding device 12 has a first handle 14 and a second handle 16. The first handle 14 and the second handle 16 are pivotably attached to each other via a pivot bearing 18. The scissors 10 are usually held so that an area of ​​the palm near the thumb rests against the second handle 16. A holding element 20, made of a plastic material, is attached to the second handle 16. This element has a raised section 22 against which an area between the thumb and index finger can be placed. The first handle 14 is typically gripped by placing the front portions of the fingers against it, allowing them to partially grasp the handle 14. A retaining element 24, made of a plastic material, is attached to the first handle 14. This retaining element 24 has a raised section 26, and in one direction from the raised section 26 to the pivot bearing 18, a kind of recess 28 is formed on the retaining element 24, into which, for example, the front portion of an index finger can be inserted. The raised section 26 prevents the hand from slipping. A spring assembly 30 with a coil spring 32 is arranged on the pivot bearing 10. The spring force of the spring assembly 30 pushes the first handle 14 and the second handle 16 apart to a maximum opening angle. In order to pivot the second handle 16 towards the first handle 14, the spring force of the spring assembly 30 must be overcome. A first scissor arm 34 is articulated to the first handle 14. For this purpose, a pivot bearing 36 is provided, which is arranged between the rotary bearing 18 and a rear end 38 of the holding device 12. A second scissor arm 42 is articulated to the second handle 16 via a pivot bearing 40. The pivot bearing 40 is also located between the rotary bearing 18 and the rear end 38 of the holding device. The pivot axes of the rotary bearing 18, the pivot bearing 36, and the pivot bearing 40 are parallel to each other. The pivot bearing 36 and the pivot bearing 40 are equidistant from a pivot axis of the rotary bearing 18. The first scissor arm 34 and the second scissor arm 42 are directly connected to each other via a pivot bearing 44. This pivot bearing 44 is located between a front end 46 of the scissor arm 10 and the pivot bearing 18. The pivot bearings 36 and 40 are located on a different side of the scissor arm 10 than the pivot bearing 44, with the sides being relative to the pivot bearing 18. The first scissor arm 34 and the second scissor arm 42 form a scissor head 48. The scissor head 48 can be closed by pivoting the second handle 16 onto the first handle 14 in order to perform a cutting movement. A pivotable locking element 50 is attached to the first handle 14. A locking knob 52 is attached to the second handle 16. The locking element 50 has a recess 54 which, in a specific pivot position of the second handle 16 relative to the first handle 14, can be slid onto the locking knob 52 so that the knob is immersed in the recess 54. When this occurs, a pivoting movement of the second handle 16 and the first handle 14 is no longer possible; a specific position of the second handle 16 relative to the first handle 14 is secured. This position is chosen such that the first scissor arm 34 is positioned relative to the second scissor arm 42 in such a way that, as will be explained in more detail below, a cutting edge located on the first scissor arm 34 is concealed. The first scissor arm 34 extends from a region 56, by means of which it is mounted on the first handle 14 via the pivot bearing 36, to a front end 58. The pivot bearing 44 is arranged in a central region 60. The first scissor arm 34 further comprises a front section 62 on which a cutting and bending device 64 is arranged, by means of which a cut can be made in a workpiece and a section of the workpiece can be bent. This will be explained in more detail below. The second scissor arm 42 extends with a section 66 from the pivot bearing 40 over a central section 68 to the front end 46. The pivot bearing 44 is arranged on the central section 68. The central section 68 holds a support device 70 onto which a workpiece can be placed during a cutting operation. The support device 70 comprises a first web 72a and a second web 72b (see, for example, Fig. 3), which are connected at one outer end by a bridge 74. The combination of the webs 72a, 72b and the bridge 74 has a U-shaped form (viewed from above). An opening 76 is formed between the webs 72a, 72b and the bridge 74, into which a workpiece working face of the cutting-bending device 64 can be inserted during the cutting operation. The central area 60 is oriented transversely to the support device 70. Furthermore, area 66 is oriented transversely to the central area 68. The transverse orientation of the support device 70 to the central area 68 is approximately 90°. The orientation of area 66 to the central area 68 is approximately 30°. By appropriately “angular” design of the second scissor leg 42, the support device 70 can be positioned below the cutting-bending device 64 (with the scissor head 48 open) and pivotably connected to the second handle 16 via the area 66. The central section 66 of the second scissor arm 42 has an opening 78 extending from the opening 76, through which the front section 62 passes. The central section 68 is thus fork-shaped, with the central section 60 of the first scissor arm 34 pivotably positioned between opposing elements 80a, 80b. The support device 70 has support surfaces 82a, 82b, which are formed on the first web 72a and the second web 72b, respectively. The bridge 74 also forms a support surface. Perpendicular to the support surfaces 82, 82b, a contact surface 84a (on the element 80a) and 84b (on the element 80b) are arranged on the central area 66 of the second scissor leg 42. The contact surfaces 84a, 84b adjoin the support surfaces 82a, 82b. When the scissor head 48 is open and the first scissor leg 34 and the second scissor leg 42 are fully pivoted apart, a flat workpiece can abut the contact surfaces 84a, 84b. The shears 10 are used for cutting metal strips. During cutting, the workpiece is placed on the support surfaces 82a and 82b of the support device 70. The support device 70 acts as a counter-support during cutting. The cutting and bending device 64 acts on the workpiece when the second handle 16 is pivoted towards the first handle 14. This pivots the first shear arm 34 towards the second shear arm 42, allowing a cut to be made. The cutting and bending device 64 includes a cutting edge 86. This is guided past a wall 88 of the support device 70, which limits the opening 76. The cutting and bending device 64 further comprises a force application area 90, which is arranged on a rear side 92 of the front area 62 of the first scissor leg 34. This rear side 92 is doubly curved or inclined in two linearly independent directions. These directions are indicated in Fig. 3 by reference numerals 94a and 94b. The force application area 90 is inclined away from the cutting edge 86; away from the cutting edge 86 in direction 94a (Fig. 5), the force application area 90 is recessed. The cutting and bending device 64, with its cutting edge 86 and force application area 90, is designed such that when a cut is made to a workpiece via the cutting edge 86, the cut workpiece area does not yet come into contact with the force application area 90. A bending of a workpiece area by the force application area 90, which occurs via the movement of the first scissor arm 34 onto the second scissor arm 42 and the insertion of the force application area 90 into the opening 76, takes place after a cut has been made. The bending thus occurs on a workpiece area that is no longer under the tension required for a cut. This significantly reduces the overall force required to cut through a workpiece. The front section 62 of the first scissor leg 34 can be formed in one piece and is in particular made of a metallic material. The cutting edge 66 is formed on this by grinding, and the force-actuating area 90 is formed. The front section 62, for example, is manufactured by metallic investment casting and, in particular, is not forged. A hold-down device 96 is arranged on the first scissor arm 34, closest to the cutting edge 86. This hold-down device is not immersible in the opening 76. Instead, it lies above the bridge 72a. When a workpiece rests on the support device 70, the hold-down device 96 acts on a portion of the workpiece during the closing movement of the first scissor arm 34 towards the second scissor arm 42, pressing it against the support surface 82a. This prevents this portion of the workpiece from snapping away during cutting. The hold-down device 96 is supported by the support surface 82a; the corresponding portion of the workpiece lies between the hold-down device 96 and the support surface 82a, and the hold-down device 96 is thus indirectly supported by the support device 70. The hold-down device 96 is elastically designed in such a way that a movement of the first scissor leg 34 onto the second scissor leg 42 is possible with the insertion of the cutting-bending device 64 into the opening 76, whereby the hold-down force is simultaneously exerted on the corresponding workpiece area. In one embodiment, the hold-down device 96 has an elastic pad 98, which is made, for example, of plastic material. This pad is fixed to the front area 62 of the first scissor arm 34 by a counter element 100. The elastic pad 98 extends along the bearing surface 82a to provide appropriate support. The elastic pad 98 of the hold-down device 96 is provided with a concave outer contour facing the support device 70 and is adapted to the shape of the support surface 82a. The scissors according to the invention function as follows: A cutting movement can be performed by moving the second handle 16 towards the first handle 14. This moves the first scissor leg 34 towards the second scissor leg 42, and the cutting edge 86 and the force-actuating area 90 can enter the opening 76 and act on a workpiece. A workpiece (a metal strip to be cut) is placed on the support device 70 with the shear head 48 open. With the shear head open, the minimum distance between the front section 62 of the first shear arm 34 and the support device 70 is finite, i.e., not zero. This distance is located at the contact surfaces 84a, 84b and is, in particular, at least 0.5 mm. In a specific embodiment, it is approximately 1.3 mm. This minimum distance allows a workpiece to generally touch the middle area 68 of the second scissor arm 42. The cutting edge 86 and the force application area 90 are designed such that pressure for bending a workpiece is only applied after a cut has been made in a corresponding area of ​​the workpiece. This is explained schematically with reference to Figures 5, 6 to 7. Figures 5, 6 to 7 show different areas along the cutting-bending device 64 during a cutting operation on a workpiece at a specific angle of the first scissor arm 34 to the second scissor arm 42. Figure 5 shows a sectional view of a workpiece area 102, which has already been cut. Subsequently, the force-application area 90 was applied, resulting in a deformation (bending) 104. Figure 6 shows another workpiece area, which follows the workpiece area shown in Figure 5, and which has been cut. The force-application area for bending is acting on this area. Figure 7 shows a workpiece area following the workpiece area shown in Figure 6, which is being cut. The force application area 90 is not yet in effect; that is, no bending is taking place. This means that a cut is being made in the workpiece area shown in Figure 7 without applying pressure through the force application area. In the workpiece areas shown in Fig. 5 and Fig. 6, a cut was already made and then a bend was subsequently performed. When cutting a workpiece in the form of a metal strip, a cutting operation and a bending operation occur from a certain pivot position of the first scissor arm 34 relative to the second scissor arm 42. However, the cutting and bending operations are not performed simultaneously on the same workpiece area. Instead, a cut is made, and the same workpiece area where the cut was made is only bent—that is, it is only subjected to force application by the force application area 90—when the first scissor arm 34 pivots further towards the second scissor arm 42. At the beginning of a cutting process, only a cut is made into the workpiece. Only as the cutting process progresses, through the movement of the first scissor leg 34 towards the second scissor leg 42, does bending occur by the insertion of the force-applying area 90 into the opening 76, whereby the cutting and the bending do not take place in the same area of ​​the workpiece. The solution according to the invention does not involve separation under tension; instead, the cutting action precedes the deflection. This reduces the force required for cutting. The bending work on the same workpiece area occurs after the workpiece area has been cut. In the solution according to the invention, the cutting into a workpiece area and the deformation of this workpiece area are staggered in time. The deformation work is performed exclusively via the force application area 90, that is, via an underside of the front area 62 of the first scissor leg 34. A cut area is bent inwards. It has been shown that, for example, metal strips with a thickness of approximately 1 to 1.2 mm and a width of 32 mm can be cut by hand, requiring relatively little force.

Claims

Scissors for cutting metal strips, comprising a scissor head (48) with a first scissor arm (34) and a second scissor arm (42), which are pivotable relative to each other, wherein a cutting-bending device (64) with a cutting edge (86) and a force application area (90) for bending a workpiece area (102) is arranged on the first scissor arm (34), and a support device (70) for the workpiece with an opening (76) into which the cutting-bending device (64) can be immersed is arranged on the second scissor arm (42), characterized in that the cutting-bending device (64) is designed such that the force application area (90) only acts on a workpiece area (102) after a cut has been made on the workpiece area (102), and that with the scissor head (48) fully open, there is a minimum distance between the The support device (70) and the cutting edge (86) are present, which is finite,wherein the minimum distance is at least 0.5 mm, and that a contact surface (84a; 84b) for a workpiece is formed on the first scissor leg (34) and / or second scissor leg (42), which is oriented transversely to a support surface (82a; 82b) of the support device (70), and which is effective when the scissor head (48) is fully open. Scissors according to claim 1, characterized in that the force application area (90) is arranged directly next to the cutting edge (86). Scissors according to claim 1 or 2, characterized in that an impact surface of the force application area (90) is curved or inclined in a first direction (94a) and is inclined or curved in a second direction (94b). Scissors according to claim 3, characterized in that the force application area (90) is inclined or curved away from the cutting edge (86). Scissors according to one of the preceding claims, characterized in that the force application area (90) is formed by an underside area of ​​the first scissor leg (34). Scissors according to one of the preceding claims, characterized in that the support device (70) is U-shaped. Scissors according to one of the preceding claims, characterized in that the support device (70) has a wall (88) limiting the opening (76), past which the cutting edge (86) is guided. Scissors according to one of the preceding claims, characterized in that an elastic hold-down device (96) for a workpiece is arranged on the first scissor leg (34), which can be supported on the support device (70). Scissors according to claim 8, characterized in that the hold-down (96) comprises an elastic pad (98). Scissors according to one of the preceding claims, characterized by a holding device (12) with a first handle (14) and a second handle (16) which are pivotably connected to each other, wherein the first scissor leg (34) is pivotably connected to the first handle (14) and the second scissor leg (42) is pivotably connected to the second handle (16). Scissors according to claim 10, characterized in that the holding device (12) comprises a spring device (30) which is arranged and designed such that a force against a spring force of the spring device (30) is required to pivot the second handle (16) onto the first handle (14). Scissors according to claim 10 or 11, characterized in that by pivoting the second handle (16) towards the first handle (14) the first scissor leg (34) and second scissor leg (42) can be pivoted towards each other.

Images