Reasons for deformation of hot press plate

During the production process, the multi-layer press frequently loads slabs and sends out rough boards. Sometimes, hard objects (such as bolts, iron blocks, etc.) may be brought into the hot press with the slabs, or there may be missing slabs in a certain interval of the laminated board. At this time, when the hot press machine is pressurized, it is subjected to the dual effects of temperature and pressure, and the hot press plate often has pits, cracks, deformation, and uneven temperature. The pressed rough board also has white spots, local softness, tiger spots, wrinkles, and uneven thickness of the hard layer after sanding, which greatly affects the product quality. Especially after the deformation of the hot press plate, there is a large deviation in the thickness of each layer of the blank, some of which are too thick. During sanding, the hard layer on the surface of the plate is sanded off, and during sanding, the surface of the plate is not sanded. In order to reduce quality problems such as sanding failure, rough and soft board surface, it is often necessary to increase the thickness of the rough board and the hard layer of the board surface to ensure the minimum sanding allowance. This not only increases the production cost of the product, but also causes quality defects such as uneven density of the rough board, warping and deformation of food enterprise standard filing, and brings difficulties to the adjustment of the sanding machine.

Analysis of the causes of deformation in hot pressed plates

Undoubtedly, the main reason for the large thickness deviation of the raw board produced by the multi-layer hot press production line is due to the deformation of the hot press plate. In recent years, we have conducted research and analysis on the deformation of hot pressed plates and found that the deformation of hot pressed plates is mostly regular transverse and longitudinal deformation, which is mainly due to the following reasons:

1) Uneven heating, rapid temperature rise during preheating, especially during cold start-up preheating, is more prone to deformation.

2) Heating with steam, sometimes the steam pipes inside the hot press plate are not smooth or clogged due to scaling, resulting in uneven conduction during heating and uneven temperature rise in various parts of the hot press plate, which has caused hot press deformation; Sometimes the discharge of condensed water is not smooth and it is difficult to control the temperature, which can easily cause deformation of the hot press plate.

3) During the production process, situations such as missing or short slabs, or individual slabs with low density may occur, causing pressure to concentrate on the thickness gauge and leading to deformation of the hot press plate. 4) If the hot press machine is not running smoothly, the unloading rack is stuck, and the rear slab collides with the front rough slab, it will cause the fibers in the front of the slab to pile up. If the operator cannot detect it in time, the pressure increase of the hot press machine can easily cause bending and deformation of the hot press plate.