US3497203A - Clamping device for paper cutting machines - Google Patents

Description

Feb.v 24,` 1970 w..K-RUG ETAL CLAMPNG DEVICE FOR PAPER CUTTING MACHINES Filed llay 23, 1967 M n m :um E u rO WMM/m M mw wm Y, B

United States Patent O 3,497,203 CLAMPING DEVICE FOR PAPER CUTTING MACHINES Wilhelm Krug and Ludwig Priester, both of 13-17 Schickhardtstrasse, 7460 Balingen, Germany Filed May 23, 1967, Ser. No. 640,540 Int. Cl. Bb 5/08 U.S. Cl. 269-236 9 Claims ABSTRACT OF THE DISCLOSURE This invention concerns a clamping device for paper cutter in which a single hand-operated lever controls the vertical movement of a pressure bar. The lever has an eccentric cam that bears against a bearing member having a surface that matches the contour of the cam and is connected by a pivot pin to a bar which in turn is connected through triangular levers to the pressure bar. The triangular levers are also pivoted in the xed portion of the structure to produce a reaction force that causes the pressure bar to move downward when the lever is pivoted one Way and to move upward when the lever is pivoted in the opposite direction. In either position of the lever, it is held fast against undesired movement and it provides a fast-operated pressure device capable of achieving high pressures and also of applying the pressure and releasing the pressure rapidly.

This invention relates to a clamping device for paper cutters, and more particularly to a clamping device that may be rapidly operated to clamp paper in place.

In clamping devices for paper cutters, in addition to preventing the material to be cut from being moved away from the cutting knife, it is necessary to keep the paper in its proper position during the entire cutting cycle. Because the positioning and holding of the paper by hand is unsafe, it is normally necessary to use a clamping device or a clamping plate which is disposed on top of the paper and pressed against it during the cutting cycle so that the paper is securely held between the cutting table and the clamping piece.

Previously known clamping plates are usually operable by a clamp spindle to raise and lower the clamping plate and to provide the desired pressure by tightening the spindle. These prior systems are cumbersome and slow because of the necessity of lengthy turning of the spindle wheel or similar device.

In addition to the spindle method, levers have been used to raise or lower the clamping piece and although this construction is very simple, it does not guarantee that the clamping pressure will be properly maintained during the entire cutting cycle. In addition there is the possibility of using hydraulic clamping means which allows for fast and easy clamping action and ready adjustment of pressure applied to the material to be cut, however, such hydraulic devices are relatively complicated and expensive and are only economical for use on large machines.

It is an object of this invention to provide a clamping device for a paper cutting machine that provides for constant pressure to be maintained on the material to -be cut during the entire cutting cycle and at the same time provides for fast and facile clamping.

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A further object of this invention is to provide such a clamping device that provides for a mechanical adv'lntage for manually clamping the material to be cut in p ace.

It is an additional object of this invention to provide such a paper clamp that is automatically retained in the clamped position.

It is another object of this invention to provide such a clamping device that is relatively inexpensive to manufacture and simple to operate.

It `has been found that the foregoing objects and other advantages can be readily obtained in a clamping device for paper cutting machines having a housing and a clamping plate movably mounted on the housing to hold paper in a fixed position for cutting. A manually actuatable lever is operably connected to the clamping plate to provide a mechanical advantage for securely positioning the clamping plate in engagement with the paper to be cut. Linkage means is connected to the clamping plate and is operable by the lever for moving the clamping plate relative to the housing. Cam means are provided to be operable by the lever to give additional mechanical advantage for operation of the clamping device. The cam means is engaged with the linkage means for imparting movement thereto to position the clamping plate in engagement with the paper to be cut.

The linkage means may have a bearing member upon which the cam means is slidable to move the linkage means and the clamping plate upon actuation of the lever. In addition the bearing member is adapted to be frictionally retained by the cam means in order to hold the linkage means in a fixed position so that the clamping plate is retained securely in engagement with the paper to be cut. The bearing member is pivotally mounted on the linkage means and has a bearing surface adapted t0 be slidable on and to frictionally engage a cooperating surface of the cam means. Desirably, the bearing surface is configured to conform to the cooperating surface of the cam means for at least one half of the area of the bearing surface.

The cam means may be in the form of an eccentric cam rotatable relative to the housing and frictionally engageable with the linkage means. The cam member may have a surface defining a portion of a circle and be eccentrically mounted for rotation on the same axis as the lever to provide an additional mechanical advantage for operation of the clamping device.

The linkage means in the disclosed embodiment has an actuating member engageable by the cam means and connected to a second lever which is pivotally mounted on the housing and operably connected to the clamping plate. A pair of second levers may be connected to opposite ends of the actuating member and connected to the clamping plate by a pair of pivotable links in order to impart the force of the manually operable lever and cam means to the clamping plate.

Other objects and advantages will be readily apparent from the following detailed description and the attached drawings wherein:

FIGURE 1 is a fragmentary side elevation View illustrating the clamping device of this invention for use with paper cutting machines with the parts illustrated in the starting position in solid line and in the clamped position in phantom line.

FIGURE 2 is an enlarged fragmentary view of the bearing member and cam of the clamping device illustrated in FIGURE 1.

Referring now to the drawing there is illustrated in FIGURE 1 the clamping device of this invention for paper cutters having a clamping plate, generallydesignated by the reference numeral 1, shown in its upper or initial position with its lower edge 2 positionedfor engagement with paper (not shown) to be cut upon move ment in the direction of the arrow 4. The clamping plate 1 is mounted for sliding movement by a pair of projecting guide bars 3 mounted on opposite ends of the clamping plate 1 and partially disposed in grooves in a pair of cooperating stationary support blocks 5 that form part of a stationary housing.

In order to move the clamping plate 1 in the direction of the arrow 4, thereA is provided a generally semicircular shaped cam 6 which is eccentrically mounted for pivoted movement on the shaft 7 which is supported in a xed position on the stationary housing. The cam 6 is movable by means of a lever 8 which is xedly attachedvthereto by conventional fastening means and also pivotally mounted on the shaft 7 for movement in the direction of the arrow 9.

To translate the clamping plate 1 by movement of the eccentric cam 6 there is provided a movably mounted actuating bar 10 that is connected at opposite ends 11 to a pair of toggle linkages each connected to the clamping plate 1. Each of the toggle linkages has a triangular shaped lever 13 rotatably mounted on a pivot pin 12 which is supported on the stationary housing. The lever 13 is mounted on the pin 12 on a irst apex and is rotatably attached to the bar 10 at a second apex.

A pair of links 14 are each pivotally mounted at their lower portions on the ends 15 of the clamping plate 1 and their opposite ends are each attached to the third apex of the triangular levers 13. The levers 13 are shaped so that there is a greater distance between the pivot pin 12 and the third apex connected to the links 14 than the distance between the pivot pin 12 and the secondvapex connected to the bar 10 to provide for the desired movement of the clamping plate 1.

The actuating bar 10 has a protruding arm 16 which is positioned closer to one end 11 than to its opposite end and carries a bearing member 17 made of resistant material which is pivotally mounted thereon. The bearing member 17 has a surface 18 which engages a surface 19 of the eccentric cam 6, and as illustrated in FIGURE 2, the surface 18 is only curved over a portion of its area as it becomes flat in the area indicated by the straight line 21. This configuration of the surface 18 provides for a desirably smooth and effective operation of the eccentric cam 6 and in addition, provides a bearing surface between the eccentric cam and the bearing member 17 that is large enough to provide a retardng effect so that the lever 8 and the clamping plate 1 are retained in the desired position.

When it is desired to lower the clamping plate 1 in the direction of the arrow 4, towards paper (not shown) to be retained in the position for cutting, the hand lever 8 with the eccentric cam 6 is moved in a direction of the arrow 9. As a consequence of the action of the eccentric cam 6, the bearing member 17 is forced in the direction of the arrow 22 which causes a movement of the actuating bar 10 in the direction of the arrow 23. As a result the levers 13 are pivoted in the direction of the arrow 24 which causes a lowering of the links 14 and the clamping plate 1 into the clamping position illustrated in dotted line in FIGURE 1 for holding paper (not shown) securely in position for cutting. Because of the particular dimensions of the lever 8, bar 10, the pair of levers 13 and the links 14, a mechanical advantage is provided to apply a larger force than that applied manually to the lever 8 for effectively securing the paper to be cut in a tixed position.

When it is desired to raise the clamp in order to release the material that has been cut, the hand lever 8 is swung in a direction opposite to the arrow 19 so that the bearing piece 17 is released from contact with the actuating bar 10. A tension spring 25 which is fastened on one end to the stationary housing and on its other end to the bar 10 biases the bar 10 together with the pair of levers 13 and the links 14 into the initial position, illustrated in solid line in FIGURE 1, thereby raising the clamp 1 into its upper position and releasing the paper that has been cut.

Accordingly, the clamping device of this invention provides for maintaining a constant pressure on the material to be cut during the entire cutting cycle and at the same time provides for fast and facile clamping action. In addition the clamping device furnishes a mechanical advantage for manually clamping the material to be cut and at the same time provides for automatically retaining the clamping plate in the clamped position. Further, the clamping device of this invention is relatively inexpensive to manufacture and is simple to operate.

It will be understood that the foregoing description with the details of exemplary structure is not to be construed in any way to limit the invention, but that modiications may be made thereto without departing from the scope of the invention as set forth in thefollowing claims.

Having thus described the invention, we claim:

1. A clamping device for paper cutting machines comprising: a housing, a linearly movable clamping plate mounted on said housing to hold paper in a xed position for cutting; a manually actuatable lever operably connected to said clamping plate providing a mechanical advantage for securely positioning said clamping plate in engagement with paper to be cut; linkage means comprising a plurality of related elements connected to said clamping plate and operable by said lever for moving said clamping plate relative to said housing; and cam means operable by said lever providing an additional mechanical advantage for operation of said clamping device, said cam means being engaged with said linkage means for imparting movement thereto to position said clamping plate in engagement with the paper to be cut.

2. The clamping device of claim 1 wherein said linkage means has a bearing member upon which said cam means is slidable to move said linkage means and said clamping plate upon actuation by said lever, and wherein said bearing member frictionally retains said cam means to hold said linkage means in a fixed position so that said clamping plate is retained securely in engagement with the paper to be cut.

3. The clamping device of claim 2 wherein said bearing member is povotally mounted on said linkage means and has a bearing surface adapted to be slidable on and to frictionally engage the cooperating surface of said cam means.

4. The clamping device of claim 3 wherein said bearing surface is configured to conform to the cooperating surface of said cam means for at least one half of the area of said bearing surface.

5. The clamping device .of claim 1 wherein said cam means has an eccentric cam member rotatable relative to said housing and frictionally engageable with said linkage means.

6. The clamping device of claim 5 wherein said cam member has a surface defining a portion of a circle and is eccentrically mounted on the same axis as said lever.

7. The clamping device of claim 1 wherein said linkage means has an actuating member engageable by Said cam means and which is connected to a second lever pivotally mounted on said housing and operably connected to said clamping plate.

8. The clamping device of claim 7 wherein a pair of said second levers are connected to opposite ends of said actuating member and wherein said second levers are connected to said clamping plate by a pair of pivotable links.

9. A clamping device for paper cutting machines comprising: a housing; a clamping plate movably mounted on said housing to hold paper in a fixed position for cutting; a manually actuatable lever pivotally mounted on said housing and operably connected to said clamping plate providing a mechanical advantage for securely positioning said clamping plate in engagement with paper to be cut; an eccentrically mounted cam rotatable by said lever providing an additional mechanical advantage for opera-l tion of said clamping device; and linkage means comprising a plurality of related elements connected to said clamping plate, one of said elements comprising a bearing member pivotally mounted thereon adapted to be slidable UNITED STATES PATENTS 4/1867 Morse 269-235 X 3/1941 McKenna 269-229 10 ROBERT C. RroRDoN, Primary Examiner D. R. MELTON. Assistant Examiner

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