The Best of Both Worlds –the New Dieffenbacher CPS+ Press

Dieffenbacher has over 25 years of experience in the construction of continuous presses with its CPS. The ContiPlus press manufactured by subsidiary SWPM in Shanghai adds a further 15 years of experience. The Dieffenbacher Group has had success on the market with both press systems. Both systems are used in all regions around world. Altogether, around two hundred presses have been built and put into operation.

Some features of their design differ, but they are united by essential factors – both press systems deliver on their promise to the panel producer: reliable and efficient production of high-quality wood-based panels. Dieffenbacher engineers are now using the experience gained from CPS and ContiPlus to develop the new CPS+. The CPS+ combines the best mechanical design features of both previous press systems to create a unique press design with further improved properties.

Quick and Safe

The new maximum speed of the CPS+ in thin panel production is 2,500 mm/s. This is an increase of 20% compared its predecessor. This also means up to 20% higher capacity. THDF production using the new press is safer than ever despite the high speed. An X-ray sensor monitors the mat immediately before the proven Dieffenbacher double hinge press infeed. If mat flaws or distortions are recognized, the press cylinders are immediately released and the press stops automatically. The brake system was also reinforced for this purpose. Optimized bending rods and chains ensure smooth stopping.

Double-action multipot cylinders at the first three press frames support the instant pressure relief when the Press Infeed Protection system (PIP) activates.

This patented, unique safety package, known as Press Infeed Protection (PIP), is included in the CPS+ standard equipment for wood-based panels under 6 mm thick, manufactured at speeds higher than 1,200 mm/s. PIP can also be optionally installed in all other CPS+ models. Earlier models can of course also be retrofitted with the safety package.

Faster Heat Transfer

Mats are subjected to high pressure, even in the press infeed. The load on the heating plate is correspondingly high. Dieffenbacher heating platens are protected from damage by hardened protection platens. A new feature is that the first protection platens with which the mat comes in contact are also equipped with heating ducts, making them thermoactive. This enables heat, as well as pressure, to be transferred from the press to the mat at an earlier stage.

The effect is considerable. The resulting surface temperature is around 20 Kelvin higher right at the beginning of the procedure. This allows the mats to be heated through to 100°C 10 to 20 seconds earlier which speeds up the resin curing in the calibration zone. The pressure factor is lowered and the cost-effectiveness of the CPS+ increased accordingly. Measurements taken with customers showed a steel belt surface temperature increase of 20 Kelvin at the press infeed. Thus heating the mat up to 100° Celsius could be reached 18 seconds earlier. Press factor decreased accordingly.

The heating platens are defended by protection platens. Yet, in order to ensure a quick heat transfer to the mat, the protection platens are heated as well.

Rigid yet Flexible

The frame structure of the CPS+ is similar to the previous CPS. The modular frame made from four frame elements has been retained. The construction of the internal cylinder press was adopted from the ContiPlus. In the CPS+, the cylinders are already pre-installed in the upper frame assembly, which reduces build time. This modular design offers several advantages compared to one-piece window frames. Firstly, it reduces maintenance and repair times. Secondly, it enables subsequent extension of the press with minimal downtime as long as the foundation and press pit have been prepared.

Modular frame design with integrated pre-assembled pressure cylinders.

Product Changeover without Interruption

A feature of the CPS proven over decades is the extrainment of the frames while thermal expansion of the heating platens. This is also an important quality characteristic of the new CPS+. When the heating platens expand due to increased temperature, all frames – installed on sliding platens – move along with the heating platens, including the internally mounted cylinders. This allows product changeovers that also entail a change in temperature of the heating platens to be carried out without interruption, i.e. without being run out.

Optimum Pressure Distribution

The Parallel Press Gap System minimizes any „breathing out“ effect in the as yet unhardened panels between the two banks of cylinders. This has also been standard in the CPS for many years. The forces of the top cylinders and the opposing forces of the lower frame elements are offset in a longitudinal direction. To do this, the thickness of the heating platens and roll platens, the number of cylinder banks and the top and bottom frame intervals are defined and coordinated so that the pressing gap between the frames only has minimal variation and always runs almost in parallel. Uniform pressure distribution in the longitudinal direction saves huge amounts of resin. Further consequences are excellent thickness tolerances and outstanding surface quality of the wood-based panels.

Top: The Dieffenbacher Parallel Press Gap System ensures minimum press gap variations between the cylinder frames.
Bottom: The reliable arrangement of the cylinders and frames ensures a constant parallel press gap.

All under Control

The press cylinders impact directly on the heating platens from above, as in the ContiPlus made by Dieffenbacher SWPM. The cylinders at the left and right borders of a bank act individually or jointly depending on the intended application. They are used to adjust product width purely hydraulically. The central cylinders in a cylinder bank are controlled either individually, in pairs or in groups depending on pressure zone. If necessary, this can be fully automated with the advanced Proguide+ control system.

The cylinder banks are also fitted with different numbers of cylinders in the longitudinal direction. They sit offset in relation to one other and so homogenize the surface of the produced panels. The thickness of the panel is measured across the width immediately after leaving the press. The control system then automatically controls the pressure of the hydraulic cylinders in the calibration zone. This loop of measurement and regulation is responsible for the excellent thickness tolerances of the CPS+ across the panel width.

Offset placed cylinders homogenize board surface.

Safe Steel Belt Operation

A further important innovation of the CPS+ is the automated orthogonal adjustment for flawless steel belt operation, which is continuously measured. If the steel belt is operating under load, a motorized mechanism affects the operation of the rolling rods. The rolling rods have their direction altered by tenths of a millimeter so that the steel belts automatically return to their ideal running position. Time-consuming manual adjustment of steel belt operation is a thing of the past and press misalignment is eliminated. This not only increases the operational reliability and service life of the steel belt and machine parts, it can also increase the availability of the plant and reduce the use of resin.

The diameter of the steel belt drums on the press infeed has been increased by 15%, the number of guide rollers optimized, and the steel belt guidance made smoother in the backward direction. All of these changes significantly reduce undesirable kinking and bending influences on the steel belt and ensure a correspondingly longer service life. Furthermore, the CPS+ can now also be operated with steel belts up to 3.5 mm thick. This is particularly advantageous for OSB plants and when manufacturing higher-density panels.

A Clean Machine

Ease of maintenance was also considered when developing the CPS+. The supply side and maintenance side of the press are clearly separated. This makes it much easier to access the press and its internal components. Wear parts can be replaced very quickly. The press pit is also tidy and clean. Valve blocks and the control cabinet are installed at ergonomic working heights to simplify maintenance and care of the continuous Dieffenbacher press. Last but not least, the CPS+ endeavors to set new standards in the field of emission protection. The new extraction system collects fumes from the pressed mat (directly at the press gap and above the press) and delivers them to the appropriate air pollution control device.


The new continuous press CPS+

Highlights at LIGNA 2015:

ligna 2015