Pressing arrangement

Abstract

The present invention relates to an arrangement for treatment of articles by hot pressing. The pressing arrangement for treatment of articles by hot pressing comprises a pressure vessel including: a furnace chamber comprising a heat insulated casing and a furnace adapted to hold the articles. A heat exchanger unit is arranged below said furnace chamber and adapted to exchange thermal energy with pressure medium when the pressure medium is passing through said heat exchanger unit. According to the present invention, at least one first and second inlet or aperture, respectively, for passage of alternating warm and cold pressure medium are arranged in the heat insulated casing in proximity to the heat exchanger unit (i.e. at approximately same the height as, above or below the heat exchanger unit). The at least one second inlet (or lower inlet) is below the at least one first inlet (or upper inlet) but at same height as or below the heat exchanger unit.

Claims

1. A pressing arrangement for treatment of articles by hot pressing, comprising: a pressure vessel comprising a furnace chamber comprising a heat insulated casing and a furnace adapted to hold the articles, the heat insulated casing comprising a heat insulating portion and a housing part, a heat exchanger unit arranged below said furnace chamber and adapted to exchange thermal energy with a pressure medium when the pressure medium is passing through said heat exchanger unit, a guiding passage, formed between the housing part and the heat insulating portion, for guiding the pressure medium, at least one first inlet arranged in said heat insulated casing at a lower part of said heat insulated casing, the at least one first inlet being provided in at least one first opening in the heat insulating portion for passage of the pressure medium into said guiding passage, and at least one second inlet arranged in said heat insulated casing at said lower part of said heat insulated casing, the at least one second inlet being provided in at least one second opening between the heat insulating portion and the housing part for passage of the pressure medium into said guiding passage, said at least second inlet being located below said heat exchanger unit in a vertical direction and in a flow direction of the pressure medium in the guiding passage during a cooling phase, said at least one first inlet being located above said heat exchanger unit in a vertical direction and in a flow direction of the pressure medium in the guiding passage during a cooling phase, and said at least one second inlet being arranged in relation to the at least one first inlet such that the at least one second inlet permits the pressure medium to pass into the guiding passage without having to pass through the at least one first inlet.

2. The pressing arrangement according to claim 1, wherein said guiding passage is arranged to guide pressure medium from said heat exchanger unit supplied via said at least first inlet and said at least second inlet.

3. The pressing arrangement according to claim 2, wherein said guiding passage is provided with at least one outlet for passing said pressure medium towards at least one of a top of said pressure vessel and side walls of said pressure vessel.

4. The pressing arrangement according to claim 1, wherein said heat exchanger unit is arranged between said at least one first inlet and said at least one second inlet.

5. The pressing arrangement according to claim 2, wherein said heat exchanger unit is arranged between said at least one first inlet and said at least one second inlet.

6. The pressing arrangement according to claim 1, wherein a bottom insulating portion is arranged below said furnace chamber and above said heat exchanger unit.

7. The pressing arrangement according to claim 6, wherein said bottom insulating portion is arranged at the same height as the at least one first inlet.

8. The pressing arrangement according to claim 6, wherein said bottom insulating portion is arranged substantially above said at least one first inlet.

9. The pressing arrangement according to claim 1, wherein the opening area of said at least one first inlet is smaller than the opening area of said at least one second inlet.

10. The pressing arrangement according to claim 2, wherein the opening area of said at least one first inlet is smaller than the opening area of said at least one second inlet.

11. The pressing arrangement according to claim 1, wherein a set of first inlets are arranged at substantially a first vertical location and wherein a set of second inlets are arranged at substantially a second vertical location.

12. The pressing arrangement according to claim 1, wherein said pressing arrangement is arranged for treatment of articles by hot isostatic pressing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings. In the following Figures, like reference numerals denote like elements or features of embodiments of the present invention throughout. Further, reference numerals for symmetrically located items, elements or feature indicators are only denoted once in the Figures. On the drawings:

(2) FIG. 1 is a side view of a pressing arrangement according to an embodiment of the invention;

(3) FIG. 2 is a side view of the pressing arrangement of FIG. 1 during a steady-state phase;

(4) FIG. 3 is a side view of the pressing arrangement of FIG. 1 during a moderate cooling phase;

(5) FIG. 4 is a side view of the pressing arrangement of FIG. 1 during a rapid cooling phase;

(6) FIG. 5 is a side view of the pressing arrangement of FIG. 1 during a cooling phase of the heat exchanger unit;

(7) FIGS. 6a and 6b schematically show different inlet configurations of the upper and lower inlets;

(8) FIG. 7 schematically show a part of the press arrangement according to a further embodiment of the present invention; and

(9) FIG. 8 is a side view of a pressing arrangement according to another embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(10) The following is a description of exemplifying embodiments of the present invention. This description is intended for the purpose of explanation only and is not to be taken in a limiting sense. It should be noted that the drawings are schematic and that the pressing arrangements of the described embodiments may comprise features and elements that are, for the sake of simplicity, not indicated in the drawings.

(11) Embodiments of the pressing arrangement according to the present invention may be used to treat articles made from a number of different possible materials by pressing, in particular by hot isostatic pressing.

(12) FIG. 1 shows a pressing arrangement according to an embodiment of the invention. The pressing arrangement 100, which is intended to be used for pressing of articles, comprises a pressure vessel 1 with means (not shown), such as one or more ports, inlets and outlets, for supplying and discharging a pressure medium. The pressure medium may be a liquid or gaseous medium with low chemical affinity in relation to the articles to be treated. The pressure vessel 1 includes a furnace chamber 18, which comprises a furnace (or heater) 36, or heating elements, for heating of the pressure medium during the pressing phase of the treatment cycle. The furnace 36 may, as shown in for example FIG. 1, be located at the lower portion of the furnace chamber 18, or may be located at the sides of the furnace chamber 18. The person skilled in the art realises that it is also possible to combine heating elements at the sides with heating elements at the bottom so as to achieve a furnace which is located at the sides and at the bottom of the furnace chamber. Clearly, any implementation of the furnace regarding placement of heating elements, known in the art, may be applied to the embodiments shown herein. It is to be noted that the term furnace refers to the means for heating, while the term furnace chamber refers to the volume in which load and furnace are located. The furnace chamber 18 does not occupy the entire pressure vessel 1, but leaves an intermediate space 10 around it. During normal operation of the pressing arrangement 100, the intermediate space 10 is typically cooler than the furnace chamber 18 but is at equal pressure.

(13) The furnace chamber 18 further includes a load compartment 19 for receiving and holding articles 5 to be treated. The furnace chamber 18 is surrounded by a heat insulated casing 3, which is likely to save energy during the heating phase. It may also ensure that convection takes place in a more ordered manner. In particular, because of the vertically elongated shape of the furnace chamber 18, the heat-insulated casing 3 may prevent forming of horizontal temperature gradients, which are difficult to monitor and control.

(14) In the furnace chamber 18, there may also be located a fan 30 for circulating the pressure medium within the furnace chamber 18 and enhance an inner convection loop, in which pressure medium has an upward flow through the load compartment and a downward flow along a peripheral portion 12 of the furnace chamber.

(15) Further, the pressure vessel 1 comprises a heat exchanger unit 15 located at the bottom of the pressure vessel 1, beneath the furnace chamber 18 as well as a bottom insulating portion 7b. The heat exchanger unit 15 is arranged to exchange, dissipate and/or absorb, thermal energy with the pressure medium.

(16) The pressure vessel 1 may further comprise a fan 31, which is located beneath the furnace chamber 18, for guiding pressure medium into the furnace chamber.

(17) Moreover, the outer wall of the pressure vessel 1 may be provided with channels or tubes (not shown), in which a coolant for cooling may be provided. In this manner, the vessel wall may be cooled in order to protect it from detrimental heat. The coolant is preferably water, but other coolants are also contemplated. The flow of coolant is indicated in FIG. 1 by the arrows on the outside of the pressure vessel.

(18) Even though it is not shown in the figures, the pressure vessel 1 may be opened, such that the articles within the pressure vessel 1 can be removed. This may be realized in a number of different manners, all of which being apparent to a man skilled in the art.

(19) A first guiding passage 10 is formed between the inside of the outer walls of the pressure vessel and the casing 3. The first guiding passage 10 is used to guide the pressure medium from the top of the pressure vessel 1 to the bottom thereof.

(20) Further, the heat insulated casing 3 comprises a heat insulating portion 7 and a housing 2 arranged to surround the heat insulating portion 7, which thermally seals off the interior of the pressure vessel 1 in order to reduce heat loss.

(21) Moreover, a second guiding passage 11 is formed between the housing 2 of the furnace chamber 18 and the heat insulating portion 7 of the furnace chamber 18. The second guiding passage 11 is used to guide the pressure medium towards the top of the pressure vessel. In FIG. 8, another embodiment of the present invention is illustrated where the second guiding passage guides the pressure medium to the pressure vessel wall, which will be discussed in more detail below.

(22) The second guiding passage 11 is provided with at least a first inlet or upper inlet 24 and at least a second inlet or lower 25 for supplying pressure medium thereto, as well as an opening 13 at the top of the pressure vessel for allowing flow of the pressure medium into the first guiding passage 10. Preferably, the second guiding passage 11 is provided with a number of first inlets 24 and a number of second inlets 25 located at the approximately same vertical heights relatively to the heat exchanger unit 15, for example, arranged in rows. The first and second set of inlets 24, 25 are arranged in a lower part 26 of the heat insulated casing 3 adjacent to the heat exchanger unit 15.

(23) According to embodiments of the present invention, a set of first or upper inlets are arranged in a row pattern a set of second or lower inlet are arranged below the upper set but in a row pattern. The inlets of the set of first and second inlets may have different sizes, shapes, mutual distances (i.e. distances between two adjacent inlets), etc. Further, the inlet of the set of first and second inlets can be arranged according to a row pattern, a wave patter, a double row pattern, etc.

(24) According to embodiments of the present invention, an opening cross-section area of the at least one first inlet is smaller than an opening cross-section area of the at least second inlet. In embodiments including more than one first inlet and more than one second inlet, the sum of the opening cross-section areas of the set or group of first inlets is smaller than the sum of the opening cross-section areas of the set or group of second inlets.

(25) With reference to FIGS. 6a-6b, a number of different inlet configurations according to the present invention are shown. The figures are schematic and illustrates a part of the inside wall of the heat insulating portion 7 of the pressure vessel in rolled out condition. In FIG. 6a, one embodiment is shown where the inlets 124 of the upper set are circular with the same cross-sectional opening are and arranged with the same distance d1 between adjacent inlets and the inlets 125 of the lower set are circular with the same cross-sectional opening are and arranged with the same distance d2 between adjacent inlets. Further, the lower set of inlets 125 is arranged below the upper set of inlets 124 at a vertical distance VD. The upper set of inlets 124 is accordingly arranged at substantially a first vertical location within the pressure vessel and the second set of inlets 125 are arranged substantially at a second vertical location. As can be seen, an upper inlet 124 is not necessarily arranged directly vertically above a corresponding lower inlet 125 but may of course be arranged directly above the corresponding lower inlet. The total cross-section opening area of the lower inlets 125 (i.e. the sum of the individual opening areas) is bigger than the total cross-section opening area of the upper inlets 124.

(26) In FIG. 6b, an embodiment is shown where the inlets 224a, 224b of the upper set has two different cross-section opening areas and are arranged according to a wave form shaped pattern with the same distance d3 between adjacent inlets and the inlets 225a, 225b of the lower set has two different cross-section opening areas and are arranged according to a wave form shaped pattern with the same distance d4 between adjacent inlets.

(27) Further, the lower set of inlets 225a, 225b is arranged below the upper set of inlets 224a, 224b with vertical distances VD2, VD3, VD4, and VD5. The total cross-section opening area of the lower inlets 225a, 225b (i.e. the sum of the individual opening areas) is bigger than the total cross-section opening area of the upper inlets 224a, 224b. The lower set of inlets 225a, 225b comprises fewer inlets than the upper set 224a, 224b.

(28) According to the present invention, the heat exchanger unit 15 is preferably arranged between upper set of inlets and the lower set of inlets, and thus, according to such preferred embodiments, have a height of about VD, if an inlet pattern configuration as shown in FIG. 6a is used, and a height of about VD2-VD5, if an inlet pattern configuration as shown in FIG. 6b is used.

(29) Returning now to FIG. 1, the first inlets 24 are preferable arranged above the second inlets 25 and has a smaller total cross-section opening area than the second inlets 25. The heat exchanger unit 15 is preferable arranged at a position such that it is arranged between the first inlets 24 and the second inlets 25 as illustrated in FIG. 1 and below a bottom insulating portion 7b.

(30) Between the bottom insulating portion 7b and the heat insulating portion 7, openings (or gaps) 27 are formed.

(31) The first set of inlets 24 is preferably located at approximately the same height as the bottom insulating portion 7b, i.e. above the heat exchanger unit 15. An outer convection loop is thereby formed by the first and second guiding passages 10, 11 as well as in a lower portion, below the bottom insulating portion 7b, of the pressure vessel 1.

(32) In some embodiments, the heat exchanger unit 15 is arranged such a third passage 34 is formed between the heat exchanger unit 15 and the casing 3.

(33) Pressing of articles 5 in the pressing arrangement 100 according to FIG. 1 is substantially performed as described above.

(34) Operation of an exemplary pressing arrangement in accordance with embodiments of the present invention will now be described generally.

(35) In the following description, a treatment cycle may comprise several phases, such as loading phase, pressing and/or heating phase, cooling phase, rapid cooling phase, and unloading phase.

(36) First, the pressure vessel 1 is opened such that the furnace chamber 18, and the load compartment 19 thereof, may be accessed. This can be accomplished in a number of different manners known in the art and no further description thereof is required for understanding the principles of the invention.

(37) Then, the articles to be pressed are positioned in the load compartment 19 and the pressure vessel 1 is closed.

(38) When the articles have been positioned in the load compartment 19 of the pressure vessel 1, pressure medium is fed into the pressure vessel 1, for instance by means of a compressor, a pressurized storage tank (a pressure supply), a cryogenic pump, or the like. The feeding of pressure medium into the pressure vessel 1 continues until a desired pressure is obtained inside the pressure vessel 1.

(39) While, or after, feeding pressure medium into the pressure vessel 1, the furnace (the heating elements) 36 of the furnace chamber 18 is (are) activated and the temperature inside the load compartment is increased. If needed, the feeding of pressure medium continues and the pressure is increased until a pressure level has been obtained that is below the desired pressure for the pressing process, and at a temperature below the desired pressing temperature. Then, the pressure is increased the final amount by increasing the temperature in the furnace chamber 18, such that the desired pressing pressure is reached. Alternatively, the desired temperature and pressure is reached simultaneously or the desired pressure is reached after the desired temperature has been reached. A man skilled in the art realizes that any suitable method known in the art may be utilized to reach the desired pressing pressure and temperature. For instance, it is possible to equalize the pressure in the pressure vessel and a high pressure supply, and to then further pressurize the pressure vessel, by means of compressors, and further heat the pressure medium at the same time. An inner convention loop may be activated by the fan 30 included in the furnace chamber 18 in order to achieve an even temperature distribution.

(40) In accordance with the embodiments described herein, the desired pressure is above approximately 200 bars, and the desired temperature is above approximately 400 C.

(41) After a selected time period at which the temperature and pressure is maintained, i.e. the actual pressing phase, the temperature of the pressure medium is to be decreased, i.e. a phase of cooling is started. For embodiments of the pressing arrangement 100, the cooling phase may comprise, for example, one or more rapid cooling phases and/or a super rapid cooling phase, as described below.

(42) The pressure medium used during the pressing phase can, when the temperature has been decreased enough, be discharged from the pressure vessel 1. For some pressure mediums, it may be convenient to discharge the pressure medium into a tank or the like for recycling.

(43) After decompression, the pressure vessel 1 is opened such that the pressed articles 5 may be unloaded from the load compartment 19.

(44) With reference now to FIGS. 2-5, different phases of the process, including steady-state and particularly a moderate and rapid cooling phase, will be explained in more detail. Again, the terms hot or warm and cold are to be interpreted in relation to an average temperature of the pressure medium within the pressure vessel. Further, the arrows indicate the flow direction of the pressure medium.

(45) First, turning to FIG. 2, it is illustrated the flow directions of the pressure medium during steady-state. As can be seen, cold pressure medium that has passed downwards through the first guiding passage 10, ascends through the heat exchanger unit 15 and cools down the heat exchanger unit 15, or maintains it at a low temperature. A part of the cold pressure medium that has been passed downwards through the first guiding passage 10 flows through the second inlets 25 and into the second guiding passage 11. The pressure medium ascending through the heat exchanger unit 15 thereafter flows through the upper inlets 25 of the second guiding passage 11 and into the second guiding passage 11. The pressure medium in the second guiding passage 11 ascends and further through the opening 13. Thus, the upper inlets 24 are arranged with an opening area large enough to provide a through-flow during a steady-state or moderate cooling (as will be shown in FIG. 3) to thereby cool down the heat exchanger unit 15 or maintain it a low temperature.

(46) In FIG. 3, a moderate cooling phase is illustrated. During moderate cooling, the fans 31 and/or 30 are operated at a higher speed than during steady-state. As can be seen, cold pressure medium that has descended through the first guiding passage 10, thereafter ascends through the heat exchanger unit 15 and cools down the heat exchanger unit 15, or maintains it at a low temperature. A part of the cold pressure medium that has passed downwards through the first guiding passage 10 flows through the second inlets 25 and into the second guiding passage 11. The pressure medium ascending through the heat exchanger unit 15 thereafter flows through the upper inlets 25 of the second guiding passage 11 and into the second guiding passage 11. The pressure medium in the second guiding passage 11 ascends and further through the opening 13. However, during a moderate cooling phase, there will also be a flow downwards of warm pressure medium in the passage 12 and through the upper inlets 24. Thus, the upper inlets 24 are arranged with cross-section opening areas large enough to provide a through-flow also moderate cooling to thereby cool down the heat exchanger unit 15 or maintain it a low temperature. The flow of warm pressure medium downwards in the passage 12 and the flow of pressure medium upwards through the heat exchanger unit 15 both flow through the upper inlet 24 and thus compete of the available opening area of the inlet 24. If the flow of warm pressure medium is too high, the upper inlet 24 will be saturated and warm pressure medium will also start flowing downwards through the heat exchanger unit 15 and a cooling of the warm pressure medium can be achieved by a heat transfer from the warm pressure medium to the heat exchanger unit 15. The saturation point of the upper inlets 24 depend i.a. on the operational speed of the fans 30, 31 and the total cross-section opening area of the upper inlets 24.

(47) In FIG. 4, it is illustrated how the upper inlets are saturated during a rapid cooling phase. The upper inlets 24 are designed such that the outer wall of the pressure vessel 1 is not exposed to thermical overload or, in other words, the upper inlets 24 are designed (e.g. with respect to cross-section opening area and location relatively the bottom insulating portion 7b and the heat exchanger unit 15, and the lower inlets 25) such that the upper inlets 24 are saturated at a flow of warm pressure medium before a thermical overload of the outer wall of the pressure vessel 1 occurs.

(48) With reference now to FIG. 4, a rapid cooling phase will be discussed. During rapid cooling, the fans 31 and/or 30 are operated at a very high speed significantly higher than during steady-state and during a moderate cooling phase. Warm pressure medium flowing downwards through the passage 12 flows through the upper inlets 24 and through the heat exchanger unit 15 because the upper inlets 24 have been saturated by the flow of warm pressure medium into the second guiding passage 11. The pressure medium flowing downwards through the heat exchanger unit 15 is cooled down by the heat exchanger unit 15 due to the transfer of heat or thermal energy from the pressure medium to the heat exchanger unit 15. The cooled pressure medium flowing out from the heat exchanger unit 15 thereafter enters into the second guiding passage 11 through the lower inlets 25. Cold pressure medium descending through the first guiding passage 10 flows into the second guiding passage 11 through the lower inlets 25. This entails that large amounts of heat or thermal energy can be transferred from the pressure medium to the heat exchanger unit 15 and at the same time as thermical overload of the outer wall of the pressure vessel 1 can be avoided.

(49) In FIG. 5, it is illustrated how the heat exchanger unit 15 may be cooled down again after a rapid cooling phase. Alternatively, the heat exchanger unit 15 may be cooled down during steady-state of a subsequent process. If the rapid cooling process is interrupted at a suitable temperature, convection will cool down the heat exchanger unit 15. As can be seen, the cold pressure medium that has passed downwards through the first guiding passage 10 ascends through the heat exchanger unit 15 and cools the heat exchanger unit 15 down due to transfer of thermal energy from heat exchanger unit 15 to the pressure medium. Thereafter, warm pressure medium will enter into the second guiding passage 11 through the upper inlets 24 where it ascend and flows further through the opening 13. A part of the cold pressure medium that has passed downwards through the first guiding passage 10 flows through the second inlets 25 and into the second guiding passage 11.

(50) With reference now to FIG. 7, another embodiment of the present invention will described. In FIG. 7, only a smaller part of the pressing arrangement is schematically shown. The same or corresponding part or element will be referred to with the same reference numerals as above and the description thereof will be omitted below. In this specific embodiment, an upper thermal inlet 72, i.e. a thermally permeable portion though which heat or thermal energy can pass but that not allow pressure medium to pass through, is arranged at approximately the same height as the bottom insulation portion 7b and the heat exchanger unit 15. The upper thermal inlet 72 is arranged in the heat insulation portion 70 and is made of a thermally permeable material. A lower inlet or set of inlets 25 are arranged below the thermally permeable portion 72 in accordance with the embodiments described above.

(51) With reference now to FIG. 8, another embodiment of the present invention will described. The same or corresponding part or element will be referred to with the same reference numerals as above and the description thereof will be omitted below. In this specific embodiment of a pressing arrangement 110, the second guiding passage 11 formed between the housing 2 of the furnace chamber 18 and the heat insulating portion 7 of the furnace chamber 18. The second guiding passage 11 is used to guide the pressure medium towards the inner pressure vessel walls of the pressure vessel 1 through openings 83 of the heat insulated casing 3.

(52) Thus, the second guiding passage 11 is provided with at least a first inlet or upper inlet 24 and at least a second inlet or lower 25 for supplying pressure medium thereto, as well as openings 83 at the side of the heat insulated casing 3 (in the illustrated embodiment at the upper side) of the pressure vessel 1 for allowing flow of the pressure medium into the first guiding passage 10.

(53) Even though the present description and drawings disclose embodiments and examples, including selections of components, materials, temperature ranges, pressure ranges, etc., the invention is not restricted to these specific examples. Numerous modifications and variations can be made without departing from the scope of the present invention, which is defined by the accompanying claims.