Base paper-based cost reduction program for corrugated board production (4)

Choose the right cutting machine

Mechanical cutting machine (also known as mechanical cutting machine)

The cutting machine is mainly used for horizontal cutting of cardboard. It consists of transmission system, upper and lower knife rolls, double crank mechanism, and continuously variable transmission. The power source of the mechanical cross cutting machine mainly comes from the main shaft, and drives the knife roller shaft to transmit power through continuously variable transmissions and gears, etc. The speed ratio of the continuously variable transmission can be changed to obtain different rotational speed outputs and cut different length cardboard. The cardboard coming from the slitting and creasing machine has been slit into two parts in the longitudinal direction (board movement direction). In order to cut two different specifications of length of cardboard at the same time, two sets of cutting devices (two sets) are used in the general production line. Figure 5 shows the structure of the double-group cutting machine. The two units are combined in the production line. The longitudinally-overlaid cardboard is cut by the first cutting mechanism and then output by the lower receiving tape. The second part of the cardboard is produced by the second set. The cutting mechanism cuts the output of the upper fiber of the back fiber. The upper and lower cross-knife are not parallel on the upper and lower knife roller shafts, but are installed spirally or in an inclined line. In the cutting process, the entire width direction: the lower blade is not in contact at the same time, but a shearing process, gradually transitioning from the width end to the other end, its purpose is to reduce the instantaneous shear power and improve the shear The quality, at the same time, also reduces the stiffness requirements for the relevant actuators, which is very beneficial for the service life of the tool and the performance of the machine.

On a mechanical cutting machine, the cutting speed of the corrugated paperboard and the cutting edge speed of the paper cutting knife must be adjusted synchronously, and the cutting length is determined based on the shaft speed of the conveying belt. However, actually, the speed of the conveying belt and the speed of the paper sheet are slipped. Not necessarily the same, at the same time in the mechanical internal mechanism due to the error in the production of machinery and wear, etc. to determine the cutting error within the range of about 10mm. When making a single piece of corrugated board, it is appropriate to have a board that is slightly longer than the desired size. If the size of the board is shorter than the desired size, the board will be scrapped. If a carton factory produces 5 million m2 of corrugated board per month, a sheet of paper is lengthened by 5mm and the average paper width is 1.6m. The length of the paperboard bonded in one month is 312,000 meters without considering the adhesive loss. If the average unit sheet length is 2m, it can produce 15600 sheets, and an extension of 5mm is equivalent to 780m (780x1.6=12480m2). Assuming an average basis weight of 600 g/m2, about 7,488 tons of raw paper will be wasted in one month, and therefore this waste will be significant regardless of energy and raw materials. Computer cutting machines have emerged to improve the shortcomings of this mechanical paper cutter.

Computer cutting machine

The cutter of the computer cutting machine is driven by a separate DC motor to detect the speed of the paper and pulse the speed of the knife to control the cut length. Its characteristics are as follows:

Since the cutoff error is less than 1mm, the cut length error can be set to zero.

The cutting size can be changed in a short time, so the loss of time for changing the inch is zero. In the corrugated paperboard factory, it is possible to change the cutting size more than 20 times a day. Every time the mechanical cutter is changed, in order to change the length of the cut, during the operation of the continuously variable transmission, there is a loss of intermediate size, which is about 4 to 6 sheets of corrugated cardboard at a time.

If a sheet imprinter is installed, the printed corrugated board can be cut due to the correct cut size.

It can be seen that installing a computer cutting machine on a corrugated cardboard production line can not only reduce waste, but also reduce production costs and increase production efficiency.

(Author/Chen Yongchang)

Source of Information / Corrugated Box 2005, 9