Universal shaped blanking tool

Abstract

1. A universal shaped blanking tool for installation in a press, comprising a top blade (1) and a bottom blade (2) wherein both the blades (1, 2) are composed of a quantity of shearing elements (En) that are dismountably attached to a damping plate (3) of a movable top blade (1) and to a damping plate (4) of a stationary bottom blade (2). The shearing elements (En) having side surfaces (8) and a convex shearing edge (5) and / or a concave shearing edge (6). Adjacent shearing elements (E1,2) with a convex shearing edge (5) or a concave shearing edge (6) having the radii (R1) and (R2) have side surfaces (8) that make a wedge angle (ε1 ) or a wedge angle (ε2). Normals (n1, n2) of the shearing edges (5, 6), passing through a contact point (B) of the adjacent shearing edges (5, 6), lie on one straight line that passes through centres (O1, O2) of curvature of the shearing edges (5, 6), and tangents (t1, t2) of the shearing edges (5, 6), passing through the contact point (B) of the adjacent shearing edges (5, 6), lie on one straight line wherein the following formula applies to each shearing element (n): (Formula (I)) wherein In - length of the shearing edge of element n in mm; Rn - radius of the shearing edge of element n in mm; εn - wedge angle of the side surfaces of element n in degrees.

Description

[0001] Universal shaped blanking tool

[0002] Technical field The invention relates to a universal shaped blanking tool for installation in a press, comprising a top blade and botom blade wherein both the blades are composed of a quantity of shearing elements that are dismountably attached to the damping plate of the movable top blade and to the clamping plate of the stationary bottom blade, the shearing elements having side surfaces and a convex shearing edge and / or a concave shearing edge.

[0003] Background art

[0004] Within the pressing of sheet metal parts, rectangular cut pieces, trapezoidal out pieces, or shaped cut pieces are used as blanks. in the automotive industry, these blanks are produced by dividing sheet metal coils in blanking lines, or possibly by dividing metal sheets. An advantage of dividing a coil into shaped cut pieces is that the arrangement of the cutting plan of the sheet metal coil makes it passible to save the input material.

[0005] The entire dividing of the material is carried out in shearing machines ~ mechanical presses where a particular blanking tool is clamped. In the case of rectangular cut pieces and trapezoidal cut pieces, a straight (linear) blanking tool is used; in the case of shaped cut pieces, a shaped blanking tool is used.

[0006] A straight blanking tool used in mechanical pressed consists of a top blade that is clamped to the movable part of the press (ram), and a bottom blade that is clamped to the stationary part of the press (bed). The top as well as the bottom blade are generally composed of several segments.

[0007] Straight blades are simple to produce which makes the tool costs low as compared to shaped blanking tools. Cutting with a straight tool is a universal technology and can be applied to the production of blanks for a great number of parts (pressed parts), i.e. it can be used to cut rectangular or trapezoidal cut pieces of various widths and in various cut lengths. A disadvantage of cuting with a straight tool is that the geometry of the final pressed piece that is pressed from the blank (cut piece) generally has a more or less irregular shape, which results in a relatively low utilization rate of the material of such a blank. If the blank for the pressed piece is a shaped cut piece, the material utilization rate will always be better.

[0008] A shaped blanking tool has a more complex design. The top and bottom part of the tool normally comprise their base plates that the blades are clamped to. A blade of the tool can be monolithic, or it may consist of several segments arranged adjacent to each other.

[0009] If a blade is composed of segments, then each segment only has one defined position in the tool. Thus, the resulting geometry of the blade is unalterable and such a tool can only be used to cut one particular shape of the cut piece. It means that such a blanking tool is a single-purpose one and is used to produce a blank for one particular (pressed) part.

[0010] An advantage of cutting with a shaped tool are savings of the input material of the coil. As the shape of the blade, and thus the cut piece is exactly designed and is optimized for the subsequent production operations of the pressed piece, minimal quantities of waste are produced.

[0011] A disadvantage of known shaped tools is that the shape of the blade is unalterable and they can only be used to shear a single cut piece shape. This limitation applies to a case the blade is a monolithic one as well as to a case the blade consists of several segments. Thus, for every required cut piece shape it is necessary to produce a single-purpose blanking tool with the geometry of the blade corresponding to the geometry of the cut shape. The production of singlepurpose shaped tools is complex and costly; further, there are costs related to storage and maintenance of every such produced shaped tool, there being generally several such tools in the production hall.

[0012] The problem of a high purchasing price of shaped tools is often solved in such a 5 way that a shaped tool is designed for a group of similar parts, e.g. five. This is, however, a trade-off solution as cutting with such a tool will render the material utilization rate better than cuting with a universal straight blanking tool, but at the same time worse than if each part of the given group were produced with a single-purpose shaped tool with the blade geometry adapted to the one0 particular part. In this case, the purchasing investment is higher than that of a universal straight blanking tool, but lower than for the production of several single-purpose tools.

[0013] Whether the production of the blank for a particular part is solved through a5 universal straight blanking tool or through a single-purpose shaped blanking tool (or a blanking tool for a group of similar parts) depends on the economical balance the result of which is the return on investment into the single-purpose shaped took In this balance, many factors play their role as e.g.: the shape of the required blank, size of the production series, price of the input material,0 purchasing prices of the single-purpose blanking tool etc.

[0014] It is the object of the invention to propose such a blanking tool the shape of which could be repeatedly changed to adapt its shape precisely to various shapes of required cut pieces. ^

[0015] Summary of the invention

[0016] The said object is achieved by a universal shaped blanking tool for installation in a press comprising a top blade and bottom blade wherein both the blades are0 composed of a quantity of shearing elements that are dismountably attached to the damping plate of the movable top blade and to the damping plate of the stationary bottom blade, the shearing elements having side surfaces and a convex shearing edge and / or a concave shearing edge according to the invention the principle of which is that the adjacent shearing elements with a convex shearing edge or a concave shearing edge with the radii R1 and R2 have side surfaces that make the wedge angle si or the wedge angle s2 wherein the normals of the shearing edges, passing through the contact point of the adjacent shearing edges lie on one straight line that passes through the centres of curvature of the shearing edges, and the tangents of the shearing edges, passing through the contact point of the adjacent shearing edges, lie on one straight line wherein the following formula applies to each shearing element n; whore ln- length of the shearing edge of element n in mm; Rn- radius of the shearing edge of element n In mm;

[0017] - wedge angle of the side surfaces of element n in degrees.

[0018] An advantage of the universal shaped blanking tool is that the geometry according to the invention makes it possible to repeatedly create variously shaped blades, and thus various shapes of cut pieces without the necessity" of obtaining several single-purpose shaped blanking tools.

[0019] The shearing elements do not need to be produced for a single purpose and specifically for a predefined shape of the cut piece as in the case of producing a single-purpose blanking tool Instead, a greater number of these shearing elements is produced and the required shape of the blade is obtained by a suitable arrangement of these elements in a certain sequence. This way, the shape of the blade that best corresponds to the required shape of the blank for the production of the part is achieved. A mere rearrangement of these elements makes it possible, without the necessity of further modifications of the elements, to obtain a different shape of the blade, which is suitable for the production of a different part, again.

[0020] According to a preferred embodiment, the top blade and the bottom blade comprise shearing elements with a straight shearing edge and the wedge angle of the side surfaces of 0°. According to another preferred embodiment, the side surfaces of the shearing elements are fitted with vertical grooves for mutual positioning of the shearing elements.

[0021] According to stiO another preferred embodiment, the vertical grooves have a pitch that is equal to the constant value of material removal on sharpening of the shearing edge. Brief Description of Drawings

[0022] The invention will be described in more detail with reference to several embodiment examples of a universal shaped blanking tool according to the invention, shown in the attached drawings, where individual figures show:

[0023] Fig. 1 -■ a simplified view of an embodiment example of a universal shaped blanking tool according to the invention the shearing elements of which have a convex and a corresponding concave shearing edge; Fig. 2 - a simplified view of another embodiment example of a universal shaped blanking tool according to the invention the shearing elements of which have corresponding straight shearing edges;

[0024] Fig. 3 ~ a shearing element with a convex shearing edge;

[0025] Fig. 4 - a shearing element with a concave shearing edge;

[0026] Fig. 5 ~ a shearing element with a straight shearing edge; Fig. 6 ~ a schematic view of a universal shaped blanking tool according to the invention, composed of shearing elements with convex and concave shearing edges; Fig. 7 - a schematic view of a universal shaped blanking tool according to the invention, composed of shearing elements with convex, concave and straight shearing edges: Fig. 8 ~ a schematic view of two adjacent shearing elements with a convex shearing edge and a concave shearing edge;

[0027] Fig. 9 - a schematic view of two adjacent shearing elements with convex shearing edges;

[0028] Fig. 10 - a detail of clamping a shearing element to the damping plate of the bottom blade in a top view:

[0029] Fig, 11 - a detail of clamping a shearing element to the clamping plate of the bottom blade in a side view;

[0030] Fig. 12 - a press with a universal shaped blanking tool according to the invention. Examples of embodiments

[0031] Figs. 1 and 2 show* embodiment examples of a universal shaped blanking tool according to the invention wherein for simplification just one shearing element Enof the top blade 1 and one corresponding shearing element En+< of the bottom blade 2 are displayed.

[0032] The shearing elements Enof the movable top blade 1 are dismountably attached to the clamping plate 3 of the top blade 1 and the shearing elements Er<i of the stationary bottom blade 2 are atached to the clamping plate 4 of the bottom blade 2.

[0033] AO the shearing elements Ef, have side surfaces 8 In Fig. 1 , the shearing element Enof the top blade 1 a concave shearing edge 6, and the shearing element E^5of the bottom blade 2, arranged opposite to It, has a corresponding convex shearing edge 5. These shearing elements En, arranged opposite each other, have side surfaces 8 that make the same wedge angle En.

[0034] In Fig. 2, the shearing element Er. of the top blade 1 has a straight shearing edge 9, and the shearing element Ef?i-i of the bottom blade 2Sarranged opposite to it, has a corresponding straight shearing edge 9. These shearing elements En> Enn. arranged opposite each other, also have side surfaces 8 that make the same wedge angle sn; in this case, the wedge angle snis equal to 0°.

[0035] Fig. 3 separately shows a shearing element Enwith a convex shearing edge 5, Fig. 4 shows a shearing element En with a concave shearing edge 6, and Fig. 5 shows a shearing element Erswith a straight shearing edge 9. All the shearing elements Enhave side surfaces 8 that make the wedge angle £n, and further have a negative end relief angle c.

[0036] The end relief angle a usually varies in the range of 0.3’>-5cand the wedge angle snin the range of 0° to 45°.

[0037] The shearing elements Enare provided with connecting elements for mutual positioning of the shearing elements Enon their side surfaces 8. In the illustrated embodiment examples, the connecting elements consist of vertical grooves 7 for mutual positioning of toe elements. The vertical grooves 7 have a pitch that is equal to the constant value of material removal on sharpening of the shearing edge. The pitch of the vertical grooves 7 usually varies in the range of 0.1-5 mm.

[0038] Fig. 6 schematically shows a top view of a universal shaped blanking tool according to the invention composed of shearing elements Eriwith convex shearing edges 5 and concave shearing edges 6. Fig. 7 schematically shows a top view of a universal shaped blanking tool according to the invention composed of shearing elements Enwith convex shearing edges 5, concave shearing edges 6, and straight shearing edges 9.

[0039] Figs. 6 and 7 reveal that the shearing elements En of the top blade 1 , and the shearing elements Eriof the botom blade 2 are arranged in such a way that shearing elements Er;with concave shearing edges 6 are arranged opposite shearing elements Enwith convex shearing edges 5, and shearing elements Enwith straight shearing edges 9 are arranged opposite shearing elements Enwith straight shearing edges 9.

[0040] The wedge angle snof each shearing element Enof the top blade 1 is the same as the wedge angle of the respective opposite shearing element Enof the bottom blade 2.

[0041] Individual shearing elements Enof the top blade 1 er bottom blade 2 are positioned next to each other in such a way that they are pushed to each other with their side surfaces 8 and the particular position is chosen by engagement of selected vertical grooves 7 on the facing side surfaces 8 of the adjacent shearing elements En.

[0042] Two adjacent shearing elements Enwith a convex shearing edge 5 and / or concave shearing edge 6 must maintain the so-called tangent continuity. Fig. 8 schematically shows two adjacent shearing elements E-^ with a convex shearing edge 5 and a concave shearing edge 6. Then, Fig. 9 schematically shows two adjacent shearing elements Eu with convex shearing edges 5.

[0043] To maintain the so-called tangent continuity, the rule must be observed that adjacent shearing elements Ev with a convex shearing edge 5 and / or concave shearing edge 6 having the radii R1 and R2 have side surfaces 8 that make the wedge angle or wedge angle £2 wherein the normals n1, n2 of the shearing edges 5, 6, passing through the contact point B of the adjacent shearing edges 5, 6, lie on one straight line that passes through the centres 01, 02 of curvature of the shearing edges 5, 6, and the tangents t1, t2 of the shearing edges 5, 6, passing through the contact point B of the adjacent shearing edges 5, 6, lie on one straight line wherein, the following formula applies to each shearing element n: where l.:, - length of the shearing edge of element n;

[0044] Rn- radius of the shearing edge of element n; sn~ wedge angle of the side surfaces of element n in degrees.

[0045] Points A and C in Fig. 8 are contact points of not shown adjacent shearing elements.

[0046] The value of the radius Rnof a shearing edge usually varies in the range of 50- 3000 mm. As the shearing edges of the shearing elements Enget worn, they need to be regularly resharpened. To maintain the above-mentioned tangent continuity, every shearing edge is ground by a constant material removal value that is identical to the pitch of the vertical grooves 7 on the side surfaces 8 of the shearing elements En.

[0047] When including a shearing element Eawith a resharpened shearing edge in the blade assembly and connecting it to the adjacent shearing element En, the first tooth of the grooves 7 of the ground segment will be placed into the groove of the adjacent segment that corresponds to the given material removal degree, and thus the continuity of the shearing edges of elements connected to each other can be maintained even after sharpening of seme elements.

[0048] Figs. 10 and 11 show, in a top and side view, clamping of a shearing element Ento the clamping plate 4 of the bottom blade 2 by means of a screw 10 and T-nut 11. The clamping plate 4 has T-grooves in two directions that are perpendicular to each ether; which makes it possible to position and damp the shearing element Ento the damping plate 4 in any position.

[0049] Fig. 12 shows a press with a damped universal shaped blanking tool according to the invention. The clamping plate 3 of the top blade 1 is tapered at the shearing angle <p to reduce the shearing force. The shearing angle (p normally varies in the range of 0.5o-5T

[0050] List of reference signs 1 top blade

[0051] 2 bottom blade

[0052] 3 damping plate of the movable top blade

[0053] 4 clamping plate of the stationary bottom blade

[0054] 5 convex shearing edge

[0055] 6 concave shearing edge

[0056] 7 grooves

[0057] 8 side surface

[0058] 9 straight shearing edge

[0059] 10 screw

[0060] 11 T-nut a end relief angle

[0061] Enshearing element

[0062] Sr; wedge angle of the side surfaces of element n n,-, normal of element n

[0063] On centre of curvature of the shearing edge of element n tRtangent of element n

[0064] L length of the shearing edge of element n

[0065] Rnradius of the shearing edge of element n

[0066] $ shearing angle

[0067] A contact point of adjacent shearing edges

[0068] B contact point of adjacent shearing edges

[0069] C contact point of adjacent shearing edges

Claims

CLAIMS1. A universal shaped blanking tool for installation in a press, comprising a top blade (1) and a bottom blade (2) wherein both the blades (1, 2) are composed of a quantity of shearing elements (Eri) that are dismountably attached to a clamping plate (3) of a movable top blade (1) and to a clamping plate (4) of a stationary bottom blade (2), the shearing elements (En) having side surfaces (8) and a convex shearing edge (5) and / or a concave shearing edge (6), characterized in that adjacent shearing elements (Ei.a) with a convex shearing edge (5) or a concave shearing edge (6) having the radii (R1) and (R2) have side surfaces (8) that make a wedge angle (E1) or a wedge angle (E2) wherein normals (n1, n2) of the shearing edges (5, 6). passing through a contact point (B) of the adjacent shearing edges (5, 6), lie on one straight line that passes through centres (01, 02) of curvature of the shearing edges (5, 6), and tangents (tl, t2) of the shearing edges (5, 6), passing through the contact point (B) of the adjacent shearing edges (5, 6), lie on one straight line wherein the following formula applies to each shearing element (n):wherein ln- length of the shearing edge of element n in mm;Rn- radius of the shearing edge of element n in mm; wedge angle of the side surfaces of element n in degrees.

2. The universal shaped blanking tool according to claim 1, characterized in that the top blade (1 ) and the bottom blade (2) comprise shearing elements (En) with a straight shearing edge (9) and the wedge angle (s) of the side surfaces (8) of OT3. The universal shaped blanking tool according to claim 1 or 2, characterized in that the side surfaces (8) of the shearing elements (En) are fitted with vertical grooves (7) for mutual positioning of the shearing elements (En),4. The universal shaped blanking tool according to claim 3, characterised in that the vertical grooves (7) have a pitch that is equal to the particular value of material removal on sharpening of the shearing edge.

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