Selection of doctor blade holder

Doctor blade are used in all sections of paper and board machines to remove excess water and contaminants from roll surfaces. In some applications, they are also used to remove the sheet from roll surfaces on sheet breaks or during sheet threading. Doctors must be checked and inspected on a regular basis to ensure their continued, safe, efficient operation.With the gradual increase of paper machine width and speed, the doctor blade plays an increasingly important role in cleaning the roll surface and guiding the paper during the operation of the paper machine. The correctness of the selection and application of the paper machine doctor and doctor blade It is particularly important for the performance of the paper, the stability of the paper machine, and the life of the roller.

The function of the doctor blade is mainly to clean the roller surface by applying linear pressure to the roller surface in the width direction. The pressurization of the doctor is mainly based on the weight of the blade holder or the selection of a suitable cylinder. Different blade holders and doctor blades can have different cleaning effects for different types of roller surfaces. The doctor is mainly composed of a doctor body, a blade holder, a moving device, a fixed device, etc. According to the loading mode, it is divided into self-weight type and pneumatic loading type; according to the movement mode, it is divided into fixed type and swing type, which are used for different parts and different parts of the paper machine. Material roller surface. The oscillating doctor can clean the roller surface more effectively, and can prevent the scraper from being pressed on the roller surface for a long time to protect the roller surface.

• Self-weight doctor

  The self-weight doctor presses the doctor blade by the weight of the blade holder itself. Generally, the knife is lifted and closed manually. Some important parts can be pressurized and lifted by the cylinder line pressure remotely. The self-weight doctor can adjust the pressure of the blade by fine-tuning the bolt of the blade holder.

  Manual self-weight doctor are generally used in the drying section of paper machines, while pneumatic pressure doctor are generally used in the tension rolls of the wire and press sections.

• Pneumatically loaded doctor

  Pneumatically loaded doctor are currently the most widely used, also known as DST doctor, which are applied to the rolls of various parts of the paper machine. It uses full-width airbags to pressurize the whole, so that the doctor is more evenly attached to the roller surface, which can clean the roller surface more effectively, reduce end breaks, and increase the service life of the roller.

• Airbag type double doctor

  Some tiny dirt will run to the back of the doctor through the small gap between the roller surface and the doctor blade, some will be taken away by the paper, and some will remain on the back of the doctor blade and become lumpy. When it falls off, it will cause paper breaks. When the pressure of the doctor line is too high, negative pressure will be generated on the

  Surface accumulation seriously affects paper quality. The double doctor device can overcome the above shortcomings, solve the problems of linear pressure, material and angle that cannot be solved by a single doctor, ensure the cleanness of the roller surface during operation, reduce the breakage, and effectively protect the roller surface. Double doctor are mainly used for vacuum flat rolls and press rolls.