1-10. (canceled)
11. A downhole indexing apparatus for cyclically varying a configuration or operational mode of a downhole tool according to a predetermined sequence, the apparatus comprising:
a tubular body including a throughbore;
an indexing member selectively moveable relative to the tubular body in response to a signal between a first axial position and a second axial position, wherein movement of the indexing member relative to the tubular body is defined by an indexing pin and slot coupling arrangement;
an indexing fluid chamber uphole of the indexing member, wherein the indexing fluid chamber is in fluid communication with the throughbore via an indexing chamber port; and
wherein the signal for moving the indexing member comprises change in a differential fluid pressure acting across the indexing member;
the apparatus further comprising a balance piston for supporting the indexing member at at least one of the axial positions;
wherein the indexing member is selectively movable between the first axial position and the second axial position in response to the signal, the second position comprising the supported position, and wherein the balance piston is configured to move from a passive position to an active position to support the indexing member at the second position;
wherein the indexing member is biased towards the supported position by a biasing force, and the balance piston is configured to at least partially counteract the biasing force when the indexing member is in the supported position;
wherein the balance piston is configured to engage or contact the indexing member at the second position, thereby reducing load on the indexing member and consequently the indexing pin.
12. The apparatus of claim 11, wherein the biasing force provides a preload at the supported position, maintaining the indexing member in the supported position, and wherein the balance piston is configured to reduce the preload at the supported position.
13. The apparatus of claim 11, wherein the biasing force comprises a fluid pressure force component, and the balance piston is configured to at least partially counteract the biasing force’s fluid pressure force component.
14. The apparatus of any of claim 11, wherein the apparatus is configured to expose the balance piston to a similar fluid pressure as the biasing force’s fluid pressure, and wherein the apparatus is configured to propel the balance piston towards the active position and the indexing member from the unsupported or first position towards the supported or second position with fluid from a same source.
15. The apparatus of claim 11, further comprising an indexing fluid chamber, intermediate the biasing fluid chamber and the balance piston fluid chamber.
16. The apparatus of claim 11, further comprising a coupling arrangement for controlling movement of the indexing member, wherein the coupling arrangement comprises a protrusion and a slot, wherein the protrusion engages the slot.
17. The apparatus of claim 16, wherein the slot is configured to allow the balance piston to support at least at a portion of the biasing force andor indexing force andor counterforce at the first andor second andor third andor fourth axial positions.
18. A method for cyclically varying a configuration or operational mode of a downhole tool according to a predetermined sequence, the method comprising:
transmitting a signal to selectively move an indexing member relative to a tubular body between two axial positions; and
supporting the indexing member at at least one of the axial positions with a balance piston.
19. The method of claim 17, further comprising transmitting a further signal to selectively move the indexing member relative to the tubular body to a third axial position.
20. The method of claim 19, wherein the indexing member is selectively movable between a first axial position and a second axial position in response to the signal, the second position comprising the supported position, and the second or supported position comprising an intermediate axial position, between the first and third axial positions.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A tablet rotary compression press for the manufacture of multi-layered tablets, comprising a rotationally driven rotor which has a die-plate with die-plate bores and top and bottom rams aligned towards the die-plate bores which are guided in ram guides of the rotor and are axially actuated by stationary control cams, an insertion device for a portion of the tablet-forming compacts which has two or more arms guided in a radially movable manner at the each end of which a compact is held and can be aligned towards a die-plate bore, characterized in that said rotor has circumferentially included thereon a support ring or support surfaces on which the compacts can be deposited in the positions approximately aligned towards the die-plate bores, the radial arms are disposed in the rotor, rotate therewith, and have radially movable gripping portions adapted to be radially moved to each other, and the rotor has provided therein a stationary guide with first and second guide cams the cam followers of which are interacted with by the gripping portions in order to grip a compact on the support ring or a support surface, to bring it into alignment with the die-plate bore, and to release it again.
2. The tablet press according to claim 1, characterized in that the support ring has associated therewith lifting means which lift the deposited compacts if they are between the gripping portions of an arm.
3. The tablet press according to claim 2, characterized in that lifting pins are provided which are actuated by a stationary control cam.
4. The tablet press according to claim 1, characterized in that the stationary guide has a stationary disk in the rotor above the die-plate, with guide grooves for the cam followers.
5. The tablet press according to claim 1, characterized in that the gripping portions and the cam followers each are mounted on tube lengths which telescopically interact with radial bars which are fixed to the rotor in a radial direction.
6. The tablet press according to claim 1, characterized in that the arms are pivotally supported about a horizontal axis at the radial inner end and that another stationary guide is provided which lifts said arms via a predetermined angle of rotation of the rotor.