Clamp for leaf or sheet shaped material

Abstract: Clamp for clamping one or more sheet shaped products, in particular for bundling a small stack of papers, having a clamp opening (3,9) that by means of an operating member (11, 12, 13) can be brought into a clamping position (fig.2), the operating member passing a dead centre, while in accordance with the invention an elastic strip (10) bent into a U-shape, with thicker edge portions (15) can be inserted into the clamp opening, keeping the clamp opening (3,9) open when in the releasing position and serving as a gripping surface of a small stack of papers, in said position preventing the removal of the operating member (11, 12,13).

Description: The invention relates to a clamp for leaf or sheet shaped products, comprising a base plate, a clamping plate pivotably attached thereon, a hook-lever capable of carrying out a movement from a first position in which it allows the clamping plate with at any rate one edge to be remote from the base plate, and a second position in which it presses the clamping plate with at any rate said edge against the base plate, in which movement a dead centre is passed causing the second position to be stable, spring means being present to keep the clamping plate distant from the base plate. Such a clamp is known from the American patent application US-A-2.863.202. In this known clamp the resilient means are formed by a metal joint of the base plate and the clamping plate that constitute an entity. Said joint causes the opening of the clamp when the operating member does not exert pressure on the clamping plate, but when such pressure is exerted, the clamping plate is moved downward with the said edge. The pressure that can be exerted, however, is slight, because although the operating member may press the clamping plate down, it is elastically mounted, so that the hold-down force may decrease due to the yielding of said elastic joint. A further disadvantage of said known clamp is that the combination of base plate and clamping plate constitute a fairly complicated entity, which has a relatively high cost price. The invention aims at removing the aforementioned disadvantages and at providing a clamp that can be manufactured more economically, can offer a greater clamping force with materials of the same strength and has a better grasp of leaf or sheet shaped products. The aforementioned aims are achieved in accordance with the invention by providing that the spring means is constituted by a strip bent into a U-shape made of elastic material having in the bent direction two legs of which lie with the outsides against respectively the base plate and the clamping plate, the insides of the legs constituting gripping surfaces for the products to be clamped. According to a further elaboration of the invention it is preferably provided that the base plate and the clamping plate have bendings at said edges, which lie against the ends of the legs of the strip bent into a U-shape. Said edges provide that the elastic strip bent into a U-form is retained, and consequently have a different function than the ends of the clamping plate which are somewhat bent towards the clamp opening, as indicated in the American patent specifications US-A-2.566.465 and US-A-2.863.202. In applying the invention it is important that the strip of elastic material cannot be pushed backward by the leaf or sheet shaped products inserted, as a correct positioning of the different leaf or sheet shaped products often is important. In the American patent specification US-A-2.863.202 such a limitation of the space into which the leaf or sheet shaped product can be inserted is accomplished by means of members cooperating with the operating member. It may, however, be desired to establish another value for the margin over which the products to be clamped are inserted into the clamp, thus preventing the U-shaped strip from being pushed backward. Accordingly it is provided in accordance with a further elaboration of the invention that stopping members are attached to the base plate and/or clamping plate to fix the place of the backside of the strip of elastic material. An advantageous embodiment of the invention, which has been observed in practice to be satisfactory, is described in claim 4. In this respect it is pointed out that from the American patent specification US-A-2.863.202 a rotatable connecting construction between the base plate and operating member has already been known, while the American patent specification US-A-2.566.465 describes a rotatable connecting construction between the base plate and the clamping plate, which, however, also must convey the spring force which enables the clamp to be closed. In addition, there is also a pivoting construction between the clamping plate and the operating member, which in this case, however, does not pass a dead centre. According to a simple embodiment construction of the invention it is provided that the operating member is rotatably mounted in lips extending from the base plate. In this respect it is pointed out that the latter characteristic is known per se from the American patent specification US-A-2.863.202, but that in applying the invention, where the elastic strip in the open position constantly exerts upward pressure on the clamping plate, the clamp is prevented from disintegrating, due to the connecting part of the clamping plate leaving the open loop of the bent lips. When in the invention the operating member comprises two legs enclosing an angle slightly smaller than 90°, for example 70 - 85°, it is possible to bring said member in the closed position direct along the clamping plate and, moreover, to decrease the distance between said closed position and the dead centre. A clamp in accordance with the invention can very easily be entered into the known files by simply punching holes therein that correspond to the clamping brackets of the files. The invention will hereinafter be explained, reference being made to the drawing, where: fig. 1 schematically shows an enlarged side view of a clamp according to the invention in its open position; fig. 2 shows the same in the closed position of said clamp; figs. 3,4 and 5 are full-sized top views of respectively the operating member, the clamping plate, and the base plate; fig. 6 shows a view of a strip of elastic material when applied in the invention; fig.7 shows a cross section of same strip of elastic material, and fig.8 shows another embodiment of the invention. In figures 1 and 2 a base plate is indicated by 1 with upright lips having ends bent back 2, a bent end edge 3 and openings 4 (see fig.5). Into the openings 4 a clamping plate 5 is inserted by means of lips 6 which at 7 have been bent once and then have been bent back. The clamping plate has a curve and the part located beyond 8 has a downward directed bent edge 9. An elastic spring member bent into a U-shape 10 provides that the part 8 is kept distant from the plate 1. In the bend of the lips 2 an operating member 11 with a connecting part 12, situated in an angle slightly smaller than 90° thereto, is attached by means of a shaft part 13, that has remained when stamping the parts 11 and 12, and which serves as a shaft, the bent back lips 2 being bearings. As can be observed in fig. 2, after the rotation of the manually graspable portion 11 of the operating member, the end of the hook lever 12 will come into contact with the clamping plate 5 and will push it downward. The elasticity of the clamping plate 5, which may be for instance of spring steel, allows for a relatively wide opening between the parts 3 and 9 of the clamp. The clamp, drawn so far, is easy to assemble by inserting the lips 6,7 into the holes 4 and then bending them towards the clamping plate 5,8, until the position as shown in fig.2 has been achieved. Subsequently the shaft part 13, which has remained upright in the operating member, can be brought underneath the curved part of the lips 2 . When now the folded strip member 10 is introduced, it prevents the shaft parts 13 from leaving the bent lips 2, likewise preventing the part 5 of the clamping plate from ending up in such a steep angle with the base plate 1, that removal is possible. The clamping plate 5,8 further comprises bent parts 14, which constitute stopping members for the elastic strip bent into a U-form 10. In the figs. 6 and 7 a view and a larger scale cross section are shown of a strip of elastic material from which the elastic U-shaped spring members 10 can be cut. Said strip has at its edges parts 15 with the largest thickness, which via tapering parts 16 convert into a central part 17 with the smallest thickness. The raised wall 18 leans from the bottom upwards slightly inward, which facilitates the insertion of the strip 10 between base plate 1 and clamping plate 5,8. Another embodiment of the invention is shown in fig. 8. In fig. 8 the same components as in figs. 1 and 2 are indicated by the same references, provided, however, with a prime. The clamping plate 5' is attached to a lip 20 by means of a pivoting construction 19. On said plate the arm 12' rests together with a projection 13' of the operating member 11', 12'. When now said member is rotated clockwise, 13' will move the plate 5' downward, as a result of which the clamp will be closed. Further penetration of the leaf or sheet shaped product is prevented by stops 14', which can stick into the openings 21 when the clamp is completely closed. The clamp described is capable of satisfactorily securing one single sheet of paper as well as a stack having a thickness of 1 cm. When clamping a thick stack, the thicker edges of the elastic spring member 10 may be slightly compressed, which causes the pressure of the bent lips 2 to decrease at the dead centre and deformation or breaking of said lips to be prevented. The clamp in accordance with the invention can be used not only in files, European as well as American ones with respectively two and three sets of bracket parts, but also for holding together of other stacks of leaf or sheet shaped material, such as photos, bank notes and the like, while on the one hand the rubber edges protect the product and on the other hand the clamp in closed position has a slight thickness of its own.

Claims: Clamp for leaf or sheet shaped products, comprising a base plate (1), a clamping plate (5,8) pivotably attached thereon, a hook-lever (11, 12, 11', 12') capable of carrying out a movement from a first position (fig.1), in which it allows the clamping plate (5,8) with at any rate one edge (9) to be remote from the base plate, and a second position (fig.2), in which it presses the clamping plate (5,8) with at any rate said edge (9) against the base plate, in which movement a dead centre is passed causing the second position to be stable, spring means (10) being present to keep the clamping plate distant from the base plate, characterized in that the spring means is constituted by a strip bent into a U-shape (10) made of elastic material having in the bent direction two legs of which lie with the outsides against respectively the base plate (1) and the clamping plate (5,8), the insides of the legs constituting gripping surfaces for the products to be clamped. Clamp as claimed in claim 1, characterized in that the base plate (1) and the clamping plate (5,8) have bendings (3,9) at said edges, which lie against the ends of the legs of the strip bent into a U-shape (10). Clamp as claimed in claims 1 or 2, characterized in that stopping members (14, 14') are attached to the base plate (1) and/or clamping plate (5,8) to fix the place of the backside of the strip of elastic material (10). Clamp as claimed in any of the preceding claims, characterized in that the base plate (1) and the clamping plate (5,8) at the side averted from said edge (3,9) of said plates, the back side, are pivotably connected by means of a first connecting construction (4,6,7) and that the hook-lever (11,12,11',12') is rotatably connected to the base plate by means of a second connecting construction and comprises legs enclosing an angle, one of which (11,11') is manually graspable and is considerably longer than the other (12,12') which is situated distant from the first connecting construction, but considerably closer to it than said edge of the clamping plate to press the strip of elastic material in the direction of the base plate. Clamp as claimed in claim 4, characterized in that the angle is smaller than 90°, preferably 70 - 85°. Clamp as claimed in any of the preceding claims, characterized in that the first connecting construction is effected for one thing by openings (4) in the base plate or the clamping plate, and for the other by lips (6,7) bent twiceextending from the other of the base plate or the clamping plate. Clamp as claimed in any of the preceding claims, characterized in that the operating member (11, 12, 11', 12') is rotatably attached in bent lips (2,2') protruding from the base plate. Elastic strip to be applied in the clamp as claimed in claims 1 - 7, characterized in that the strip has a cross section with at the edges a part (15) having a first thickness, followed by a transitional part (16) having a gradually decreasing thickness, and a central part (17) having a thickness smaller than the first thickness.

Inventors: STOELINGA TITUS ANNO, STOELINGA, TITUS ANNO
Applicants: CLAMPION INT SALES BV, CLAMPION INTERNATIONAL SALES B.V.
Application year: 1993
Main classification: B42F1
IPC codes: B42F1, B42F9, C14B17