HYDRAULIC HEADBOX PDF

Kazahn I have 6 month experience at paper machine in paper mill can somebody guide me for a new job. The headbox jet velocity is very important factor for manufacturing high quality paper. It is also known as hollow perforated roll or holey roll. Leave a Reply Cancel reply Your email address will not be published.

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The following key questions are answered in this module: What is the jet impingement angle? On a Fourdrinier machine, it is the angle between the stock jet and the wire as the jet strikes the wire Why is the stock jet geometry so important? Stock jet geometry is important because it affects sheet formation, and sheet formation affects both the appearance and the performance of the sheet What is the difference between "pressure forming" and "velocity forming"? Pressure forming occurs with very high jet angles, where the stock jet is forced down into the wire.

Velocity forming occurs with low jet angles, and the stock jet lands more gently on the wire. What is the "jet-to-wire ratio"? It is the ratio of the horizontal spacing to the vertical spacing between the slice lip and apron lip. It is important because it affects the jet landing point and the jet impingement angle. Sample Video Transcript Below is a transcript of the video sample provided for this module: If the stock jet speed is greater than the wire speed, the jet-to-wire ratio is greater than one.

In this case, the fibers will tend to align in the cross machine direction increasing the sheet strength in that direction. Sheet formation and sheet appearance are both impacted by the jet-to-wire ratio. When the jet speed and wire speed are almost equal, when the ratio is close to one, the fibers will be well distributed and randomly oriented in the sheet. Somewhere around a ratio of one, the machine direction and cross machine direction strengths will be about equal, creating a square sheet.

Formation and appearance are both positively affected by the squaring process. Click here to view your cart.

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hydraulic head box

The distribution tubes from the Octopus connect to the Headbox tube bank to provide uniform distribution of stock at a constant velocity, right up to the sheet edges. It has always been understood that creating Micro-turbulence is the key to maintaining deflocculated fibres. Therefore at the heart of the Headbox the turbulence generator changes the high micro-turbulence step diffuser tube bank into a square cross section to create the optimum intensity of micro-turbulence in the stock entering the nozzle area. The blended stock in the nozzle area will be uniformly accelerated towards the slice gap that determines the velocity of the stock as it exits the Headbox. The operator can easily change the slice gap stock velocity when the machine is running by using the indicator hand wheel at the front side of the machine. The Headbox is of a compact design that minimises distortion due to thermal expansion whilst providing simple and repeatable operator controls. The top lip is adjustable on set up as it is supplied with the necessary warping mechanisms to set the profile.

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HYDRAULIC HEADBOX PDF

The following key questions are answered in this module: What is the jet impingement angle? On a Fourdrinier machine, it is the angle between the stock jet and the wire as the jet strikes the wire Why is the stock jet geometry so important? Stock jet geometry is important because it affects sheet formation, and sheet formation affects both the appearance and the performance of the sheet What is the difference between "pressure forming" and "velocity forming"? Pressure forming occurs with very high jet angles, where the stock jet is forced down into the wire. Velocity forming occurs with low jet angles, and the stock jet lands more gently on the wire. What is the "jet-to-wire ratio"? It is the ratio of the horizontal spacing to the vertical spacing between the slice lip and apron lip.

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