Topic
Holddown
About: Holddown is a research topic. Over the lifetime, 486 publications have been published within this topic receiving 3179 citations.
Papers published on a yearly basis
1 / 2
Papers
Patent•
30 Nov 1983
TL;DR: In this paper, the holddown and sealing assembly of a subsea wellhead system is described, which includes a wellhead, a housing seat disposed in and connected to the well head, a casing hanger supported by the seat, a holddown assembly in the annulus between wellhead and hanger, and apparatus for applying hydraulic pressure to further actuate the seal.
Abstract: The subsea wellhead system includes a wellhead, a housing seat disposed in and connected to the wellhead, a casing hanger supported by the seat, a holddown and sealing assembly in the annulus between wellhead and hanger, a running tool attached to the hanger for lowering it into the well and initially actuating the holddown and sealing assembly, and apparatus for applying hydraulic pressure to further actuate the seal. The housing seat and wellhead are connected by breech block teeth. The seat maintains 360° bearing surface with the hanger. The holddown and seal assembly includes an upper rotating member threadingly engaging the hanger and suspending a lower stationary member. The latter includes a Z-shaped portion having a plurality of frustoconical metal rings positively connected by links. The rings form grooves housing resilient elastomeric members. Upon compression of the Z-shaped portion, the elastomeric members initially sealingly engage the wellhead and hanger and then, upon further compression, the rings deform into metal-to-metal engagement with the wellhead and hanger forming a primary seal. The seal is actuated initially by torque applied through a running tool connected to the hanger. It is further actuated by hydraulic pressure whereby a compression set of the seal is achieved. The rotating member follows further compression of the seal to prevent release of the compression set upon removal of hydraulic pressure.
90 citations
Patent•
12 Dec 1994
TL;DR: In this article, a liquid ink printer transport belt is used between a printhead and a vacuum holddown device to purge ink in the absence of the recording medium without slowing or stopping the belt.
Abstract: In a liquid ink printer transport belt located between a liquid ink printhead and a vacuum holddown device includes apertures for applying a vacuum to the recording medium and for enabling the liquid ink printhead to purge ink through the apertures in the absence of the recording medium without slowing or stopping the belt. The vacuum holddown device includes a platen located beneath the belt for applying a vacuum through the apertures and gutters or slots for collecting ink from the liquid ink printheads during printing. The combination of belt and platen or apertures and gutters or slots provides continuous communication of the vacuum to the recording media as the belt moves across the platen and through a dryer. The transport belt enables the use of a single transport for both imaging and drying.
89 citations
Patent•
14 Apr 1999TL;DR: In this paper, a vacuum holddown for sheet materials has a surface having a field of vacuum ports in which each individual port is gated, and when a vacuum is applied to the underside of the holddown, the gates close.
Abstract: A vacuum holddown for sheet materials has a surface having a field of vacuum ports in which each individual port is gated. When a vacuum is applied to the underside of the holddown, the gates close. When a sheet of material is introduced onto a region of the field, the gates only within vacuum manifold passageway covered by the material are configured to spring open, applying a suction force to the sheet via the now opened ports. The holddown thus automatically adjusts to material size. An implementation for use in an ink-jet printer with cut-sheet print media is demonstrated.
69 citations
Patent•
IBM1
TL;DR: In this paper, the authors present a method for maintenance and examination of timers for a computer system having connections in a networking system, where each connection has multiple timers, and one of the timer values is written to a global timer array for each connection such that the timer array can be scanned to determine when timeouts occur for active connections.
Abstract: System and method for maintenance and examination of timers for a computer system having connections in a networking system. Timer values in a connection table each indicate a timeout for a timer for a connection, where each connection has multiple timers, and one of the timer values is written to a global timer array for each connection such that the global timer array can be scanned to determine when timeouts occur for active connections. Sparse restart of a timer includes restarting the timer if data is communicated with a connected computer before the timeout occurs and after a predetermined time interval after timer start, and not restarting the timer if data is communicated before the timeout occurs and within the predetermined interval after timer start.
49 citations
Patent•
21 Aug 2001
TL;DR: A media holddown device attached to a sheet metal vacuum beam, the guide includes vacuum chambers in communication with the beam through openings to control the negative pressures applied to media of varying widths by a fan as discussed by the authors.
Abstract: A media holddown device a plastics vacuum guide attached to a sheet metal vacuum beam, the guide includes vacuum chambers in communication with the beam through openings to control the negative pressures applied to media of varying widths by a fan Dividing walls are provided between the chambers to maintain the value of the negative pressure larger than a predetermined value, especially for media with conventional widths An intermediate wall divides the guide into front and rear chambers to increase the control of media leading edges The number, size and pattern of arrangement of openings are selected to produce desired air flow characteristics
49 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 4 |
| 2018 | 6 |
| 2017 | 3 |
| 2016 | 1 |
| 2015 | 12 |
| 2014 | 11 |