DE1986018U - KNIFE ARRANGEMENT FOR PAPER CUTTING MACHINES. - Google Patents

Description

The invention relates to a knife arrangement for paper cutting machines, in particular for three-sided cutting machines, which have two cutting stations and work with an upper and lower knife in scissor cut.

Paper cutting machines of the type in question usually have a pressing device (hold-down) for the material to be cut, a pair of front knives, two jointly driven pairs of side knives, devices for transporting the material to be cut from the front knives to the side knives and the necessary alignment elements for the material to be cut.

In order to ensure that such paper cutting machines work properly, the (sharp) cutting edges of the upper knives must brush closely and precisely past the sharp edges of the lower knives. So, on the one hand, there must be no distance between the two knives, and on the other hand, the upper knife must not touch the lower knife. Precise adjustment of the knives is therefore necessary.

The knives wear out due to the stress of cutting. Depending on the type of paper, the stress on the machine, the thickness of the material to be cut, the quality of the knife steel, etc., the knives, mainly the upper knives, have to be removed, reground, installed and readjusted at relatively short intervals. If such machines are used in continuous operation, the knives often have to be regrinded after every shift, but no later than after one to three days.

Paper cutting machines of the type in question here almost always have to cope with very large amounts of work. In particular, they are used in production lines for the continuous trimming of book blocks, magazines, brochures and stacks of paper on three sides. If the regrinding and readjustment of the knives takes too much time, the loss of production is very high. This must be avoided.

Knife arrangements for paper cutting machines which allow simple installation and removal of the cutting knife and also enable quick adjustment by inexperienced workers are not yet known.

The aim of the invention is therefore such a knife arrangement for paper cutting machines.

In the previously known paper cutting machines, the upper knives were inserted vertically, that is, in the cutting direction. The knives were mostly screwed to the back of the knife carrier, with the threaded holes predominantly in the knife and the through holes or slots mostly were arranged in the knife holder. However, designs with through holes or slots in the knife and with threaded holes in the knife holder have also become known.

In these known knife arrangements, the screws were often difficult to access. In addition, extensive readjustments had to be made to compensate for the sharpening of the knife, often using documents. Such adjustments could only be carried out by experienced skilled workers.

Another disadvantage of these knife arrangements is that the straight surface of the upper knife sweeps past the cut surface of the stack of paper and the cutting edge of the lower knife. This creates considerable friction, which on the one hand increases the force required for the cutting process and, on the other hand, is the reason for the fact that grooves are eroded into the knives, which reduce the cutting ability of the knives and can make the knives unusable.

In the previous paper cutting machines, the lower blades were screwed to the machine bed, either standing vertically or lying flat. Some embodiments had slots and pressure screws or pads for adjusting the knives to compensate for the cut.

The difficulties involved in installing and removing the lower blades and adjusting the lower blades after grinding were the same as those described in connection with the upper blades.

In order to avoid all of these disadvantages, a knife arrangement for paper cutting machines is characterized in that the upper knife is screwed from the front against the knife holder at an angle which corresponds to the cutting angle.

This arrangement of the upper knife according to the invention is always favorable, regardless of whether the knife holder with the upper knife is pulled through the paper vertically, obliquely or with a swing cut.

It is true that a paper cutting machine has also become known in which the upper knife was screwed onto the knife holder in a vertical position from the front. In this machine, however, the knife holder and the pressing device for the material to be cut hindered each other, so that this machine is only suitable for trimming very low impacts.

In the knife arrangement according to the invention for paper cutting machines, the lower knife is clamped in the direction of the knife holder of the upper knife against a solid, vertical abutment on the machine bed by easily detachable clamping strips. This system of the lower cutter is in exact correspondence with the cutting line of the upper cutter, so that the cutting edges of the upper cutter and the associated lower cutter form a straight line.

It is advantageous if the upper knife is attached to the knife holder by means of a clamping plate. Then you can use the knife together with the clamping plate in a gauge and the knife with adjusting screws, which are on the

Already outside of the cutting machine, bring it into the correct position opposite the clamping plate. The correct knife position can then be monitored by means of dial gauges that are located in the gauge. Then you can then remove the clamping plate together with the upper knife from the gauge and attach it to the knife holder of the paper cutting machine. It is then no longer necessary to adjust the upper knife directly on the paper cutting machine. The installation and removal of the knives as well as the knife adjustment can then also be carried out by inexperienced workers.

Further useful developments of the knife arrangement according to the invention for paper cutting machines emerge from the subclaims.

In the following, the invention will be described in detail using an exemplary embodiment in conjunction with the drawings.

Figure 1 is a section through a knife assembly for paper cutting machines according to the invention. The section runs along the line A-F from Fig. 3,

Figure 2 shows a detail from Figure 1 on an enlarged scale,

Figure 3 is a plan view of a knife assembly according to the invention,

Figure 4 and Figure 5 show sections through the lower cutter, namely Figure 4 is a cross section along the line G-H outside the cutting length and Figure 5 is a

Cross section along the line J-K within the cutting length,

Figure 6 and Figure 7 show the adjustment gauge in section and in plan.

In Figures 1, 2 and 3, a knife assembly for paper cutting machines according to the invention is shown. "1" denotes a machine bed which is provided with a vertical stop surface 2. A lower knife 3 is clamped against the stop surface 2 by means of a terminal strip 4 and screws 5.

"6" denotes a stack of paper which is pressed together by means of a hold-down device 7 in the knife station.

The knife holder for the upper knife is labeled "8". The upper knife 9 is fastened to the knife holder 8 from the front by means of a clamping plate 10 and screws 11. The clamping plate 10 is provided with adjusting screws 12 with which the position of the upper knife 9 with respect to the clamping plate 10 can be adjusted.

The vertical stop 2 of the machine bed 1 and the knife holder 8 are immovably fixed against each other. The lower knife 3 is tightened against the stop 2 in the direction of the knife holder by means of the terminal strip 4 and the screw 5. This automatically ensures the correct adjustment of the cutting edge of the lower knife 3, regardless of how large the cut of the knife is during regrinding.

There still remains the correct adjustment of the upper knife 9, which is fastened obliquely from the front by means of the clamping plate 10 and the screws 11 on the knife holder 8.

As can be seen in particular from FIGS. 1 and 2, it is sufficient for this to move the upper knife 9 downwards against the clamping plate by means of the adjusting screws 12 on the clamping plate 10, since with this downward displacement the cutting edge of the upper knife executes a movement in the transverse direction, so that it can be brought exactly over the cutting edge of the lower blade 3.

The correct setting of the upper knife relative to the clamping plate can be carried out outside of the paper cutting machine in an adjustment gauge, which is shown in FIGS. 6 and 7. The clamping plate 10 is placed together with the upper knife 9 on the gauge body 13, which is modeled on the knife holder 8. The devices that have to be made in order to be able to attach the clamping plate 10 to the gauge body 13 in exactly the same way as to the knife holder 8, for example guides, centering, stops or the like, have not been shown since they are known to the average person skilled in the art.

A dial gauge 14 with a feeler 15 is attached to the top of the gauge body 13, against which the cutting edge 16 of the upper knife 9 can strike. Since the position of the cutting edge of the lower knife 3 relative to the knife holder 8 is now precisely known due to the vertical stop 2 on the machine bed 1, and since the clamping plate 10 is placed on the gauge body 13 in exactly the same way as on the knife holder 8, the upper knife 9 can be adjusted by operating the adjusting screws 12 while observing the dial gauges 14 relative to the clamping plate 10 so that after removing the clamping plate with the upper knife and reinstallation On the knife holder 8, a further adjustment of the upper knife 9 with respect to the lower knife 3 is no longer necessary.

This ensures an extremely simple, quick and safe adjustment of the upper knife outside of the actual paper cutting machine, which can also be carried out by inexperienced workers.

Both the upper knife and the lower knife are relief-ground. This can best be seen for the lower knife from FIG. 5, while the undercut of the upper knife can only be seen in FIG. 2 because of the selected scale.

Due to this relief, only the edges of the knives are pulled past each other during the cutting process, so that the friction that occurs is reduced to a minimum. In addition, there is no longer any friction between the rear of the upper knife and the material to be cut. This reduces the force required when cutting and also protects the knives.

FIG. 4 is a section through the lower cutter 3 along the line G-H from FIG. 3. The section according to FIG. 4 is placed outside the cutting length through the lower cutter.

At these points the lower knife is provided with an inclined guide bevel through which the front tip of the upper knife is safely guided against the cutting edge of the lower knife. This prevents the upper knife from touching down on the lower knife, which could occur due to the resilient properties of the knife steel.

Furthermore, it can be seen from Figures 4 and 5 that the bottom knife is ground on all four edges. This means that the bottom knife can be used 4 times, so that the bottom knife has to be sharpened relatively seldom. If one of the cutting edges of the lower blade is blunt, simply turning the lower blade is sufficient.

To make it easier to replace the lower blade, the lower blade can be provided with threaded holes into which handle bolts can be screwed. This is shown in dashed lines at "17" in FIG.

It is advantageous if the cutting stations of a three-sided cutting machine are constructed identically. Then the knives of the individual stations can be interchanged and you can get by with just one adjustment gauge.

Claims (6)

1. Knife arrangement for paper cutting machines, in which the cutting stations are each equipped with upper and lower knives that work against each other in scissor cut, the upper knife being held in an oscillatingly driven knife holder and the lower knife on the machine bed, characterized in that the upper knife (9) set against the cutting direction in a manner known per se and held on the knife holder (8) by means of a clamping plate (10) so that the knife holder (8) for the upper knife (9) is at the end outside the press beam (7) for the block to be cut ( 6) is guided that the lower knife (3) is clamped against a fixed stop in the machine bed (1) and that the upper knife (9) can only be removed from the knife holder (8) together with the clamping plate (10) and after removal relative to the clamping plate adjustable (12). 2. Knife arrangement according to claim 1, characterized in that the system 2 of the lower cutter 3 and the cutting edge of the upper cutter 9 form a straight line or a plane. 3. Knife arrangement according to claims 1 or 2, characterized in that the lower cutter is provided outside the cutting length with a guide bevel for precise guidance of the upper cutter along the cutting edge of the lower cutter. 4. Knife arrangement according to claims 1, 2 or 3, characterized in that the lower knife has a rectangular cross section and is ground on all four longitudinal edges. 5. Knife arrangement according to claims 1, 2, 3 or 4, characterized in that the lower knife is provided with threaded bores into which handle bolts can be screwed to facilitate replacement. 6. Knife arrangement according to one or more of claims 1 to 5, characterized in that the upper knife and lower knife are relief-ground.