FR2651161A1 - SHEATH POWDER FILLING MACHINE. - Google Patents

Abstract

The system comprises a rotating container (3) fitted with a propeller and surrounded by an oven, which connects through a raised end with a vacuum inlet pipe provided with filters and through its opposite end with a pipe leading to the tubular blank to be filled. The rotation of the container (3) in one direction and then in the other direction enables, due to the mixing action of the propeller, firstly an efficient degassing of the powder and then its displacement and transfer into a hopper (26) overhanging the tubular blank (8). Various elements of the system allow the maintaining of the vacuum in the system once the degassing is completed while preventing pollution of the exterior by the powder. Application to the manufacture of mechanical parts by the sintering of powders of materials which cannot be moulded.

Description

SHEATH POWDER FILLING MACHINE

DESCRIPTION

  The invention relates to a sheath powder filling machine and finds its use in particular in the manufacture of mechanical parts.

  by sintering metal powders.

  This technique is commonly used when the material used does not lend itself to molding: it is then poured in the form of powder into a sheath whose shape corresponds to that of the part to be manufactured. The sheath is then closed and subjected to high hot pressures which cause sintering of the powder. When the coin has acquired

  its cohesion, the sheath is torn and rejected.

  The main objective of the invention is to ensure the filling of the sheaths in a controlled atmosphere or preferably under vacuum in order to avoid

  degradation of powders and in particular their oxidation.

  According to other appreciable advantages of the invention, it is prevented that the powders do not spread outside the machine, and a correct filling of the sheaths is ensured by suitable sealing, transfer and packing means. These advantages allow easy handling of the same powders

  toxic and very fine like those of beryllium.

  The machine comprises a container of powder rotating under the action of a motor around a preferably oblique axis. This container is provided with an emptying orifice communicating with a vacuum pump and provided with a gas permeable and impermeable to powder filter, with a powder introduction orifice and with a powder unloading orifice. . It contains a helical system of deflection fins around the oblique axis. The sheath and the discharge opening

  of powder are connected by a pipe.

  According to various advantageous arrangements which can be used separately or in combination, the machine can comprise a flexible connection arranged between the pipe and the sheath as well as a vibration generator secured to the sheath to promote packing of the powder; or a valve communicating the sheath either with the pipe or with a suction pump; or an intermediate container intended for the transfer of the powder to the rotating container, this intermediate container then being provided with an orifice provided with a valve and attached to the filling orifice of the rotating container as well as with a

  rotating hoop that can be hung on a hoist.

  In the latter case, one can provide a nozzle provided with means of connection to a container containing the powder before filling. This nozzle is fitted with a valve and an end orifice which can be attached to

  the hole in the intermediate container.

  The invention will now be described in more detail using the appended figures illustrating a preferred embodiment of the invention: - Figure 1 is a general view of the machine; - Figure 2 shows in section the rotating container; - Figure 3 shows a powder storage container; - Figure 4 shows a container for transferring the powder; and - Figure 5 shows an equipment of

filling check.

  Figure I shows the general appearance of the machine, which has been shown here inside a sealed enclosure I, at least partially transparent and fitted with handling gloves 2 through its wall. Enclosure 1, simply sketched here, offers additional protection against contamination by toxic powders in the event of rupture of sheaths or other containers, but it should be added that the machine as designed is

  itself dustproof in normal operation.

  Certain installations related to the machine are not shown here because they are obvious to a person skilled in the art, but can however facilitate use. It can notably be a production line with conveyors which bring the empty sheaths in front of the machine before moving them away when they are filled. Airlocks are provided at the ends of the conveyors to introduce the sheaths into enclosure I or remove them. Furthermore, as will be seen later, the powder can be stored in a large volume container placed at a location not far from the machine and which is gradually emptied to supply the

machine.

  The machine comprises inter alia a rotating container 3, cylindrical with axis 4 slightly inclined on the horizontal and mO by a motor 5, a tilting intermediate container 6 used for the transfer of powder from the container where it is initially contained until rotating container 3, a table 7 on which a sheath 8 to be filled is placed and fixed by clamping and a pipe 9 disposed between the sheath 8 and

  the downstream end of the rotating container 3.

  The rotating container 3 is shown in detail in Figure 2; it consists of a cylindrical wall between two frustoconical walls 21 and 22. The first of these carries an upstream mouth 23 in which is fitted a porous sleeve 24 in the form of a cylinder and which penetrates inside the rotating container 3 The porous sleeve 24 consists of an alloy called Inconel formed from stainless steel, nickel and chromium; it is permeable to gases and impermeable to filling powder. The other frustoconical wall 22 is provided with a downstream mouth 25 which penetrates into a hopper 26 which constitutes the upper end of the pipe 9. As a result of the obliquity of the axis 4, the downstream mouth 25 is a little below the upstream mouth 23 and down

towards the hopper 26.

  The downstream mouth 25 is connected to the hopper 26 by a rotary joint 40 which makes it possible to maintain the seal between these two parts. The rotary joint 40 in fact comprises an outer sleeve 41 screwed to the hopper 26 and which surrounds an inner sleeve 42 screwed to the downstream mouth 25. The sleeves 41 and 42 are notched with grooves which receive two parallel rows of balls 43 and 44 put in place with removable caps. An annular seal 45 is clamped between the inner sleeve 42 and the downstream mouth 25, while a cable gland 46 is disposed between the sleeves 41 and 42 as well as between the rows of balls 43 and 44 and the hopper 26. Finally, an O-ring 47 is clamped between the

  outer sleeve 41 and the hopper 26.

  The cylindrical wall 20 is pierced with a filling orifice 27 which can be closed by

a plug 28.

  The rotating container 3 is provided on its internal wall with a mixing and powder transfer propeller 29 which makes three turns therein, as well as

  additional turns in the downstream mouth 25.

  Vanes 30 are arranged radially from the cylindrical wall 20 towards the inside of the container 3, between the turns of the propeller 29, for

  increase the mixing of the powder.

  An oven 31 (FIG. 1) surrounds the rotating container 3 during the treatment. This oven 31 has a cylindrical overall shape and consists of two half-shells 32a and 32b hinged one on the other so as to open or close. A locking system 33 is provided opposite the articulation system 34. The flat end walls 35 and 36 of the oven 31 are provided with a central opening 37 or 38 which, in the assembled state, surrounds with Game

  the upstream mouth 23 or downstream 25 respectively.

  The oven 31 therefore remains fixed when the rotating container 3 is set in motion. Heating is provided by electrical resistors not shown which

  line the inside of its wall.

  The pipe system 9 comprises, in addition to the hopper 26, a powder valve 50 just below this hopper 26. The valve 50 is three-way, and it is sold under the reference ND-63 ISO0 by the company CETEC ( Sax, Switzerland). It can take two positions: in the filling position, the hopper 26 is placed in communication with the sheath 8 by means of a bellows 51; in the other position, the sheath 8 is placed in communication with a vacuum suction duct 52 which terminates in a pump 53. The bellows 51 is more precisely provided with a connection flange 54 to which a flange can be screwed 55 at the top of the neck 56 of the sheath 8. A compressed O-ring between the flanges 54 and 55 makes it possible to maintain the tightness of the

liaison.

  The table 7 constitutes the plate of a vibration generator 57 started to increase the packing of the powder in the sheath 8

during filling.

  Line 9 is also provided with a level detector 58, detailed in FIG. 5, which essentially consists of a vertical tube 59 passing through an orifice 60 at the top of the

  hopper 26. An O-ring 61 maintains the seal.

  The vertical tube 59 is provided over its entire length with an electric wire 62 which terminates, at the top of the vertical tube 59, in a measurement box 63 to which also leads another electric wire 64 brought to the potential of the hopper 26. The wire 62 ends at its lower end, at the bottom of the vertical tube 59, by a socket 65 connected to a conductive cable 66 stretched by a weight 67. A crimping sleeve 68 surrounds the socket and the upper end of the cable 66 and the

keeps in place.

  Returning to FIG. 1. The rotating container 3 is extended on the upstream side, beyond the upstream mouth 23, by a pipe 72 which leads to a filter 73 impermeable to the powder at the limit of the enclosure 1 and which is then extended by a suction pipe 74 connected to a vacuum pump 75. The pipe 72 and the upstream mouth 23 are connected by a rotary joint 76 similar to the previous 40. The motor 5 is reversible and its motor shaft carries a pulley which rotates the rotating container 3 by a belt 77 stretched over

the upstream mouth 23.

  We will now describe the method of filling the sheaths 8 from the rotating container.

  3, then we will discuss the description of the filling

  preliminary of the rotating container 3, which involves means specific to the embodiment described. At the start, the level detector 58 is raised, which makes it possible to switch the valve 50 so as to empty the sheath 8 by the pump 53. The oven 31 is closed around the rotating container 3 and put into action to heat the powder. The motor 5 and the vacuum pump 75 are also started. The filling level 78 of the rotating container 3 in powder form has been indicated in FIG. 2. The height of the powder is less than the width of the propeller 29, so that the powder is divided into separate quantities that the rotation of the propeller 29 moves along the axis 4. The motor 5 rotates in this direction in the direction which corresponds to the upstream movement of the powder, which accumulates on the sleeve 24 and falls periodically. The resulting stirring, joined to the heat, promotes degassing of the powder by the vacuum pump 75. The sleeve 24 theoretically prevents the powder from passing through the pipe 72 and from there to the outside; filter 73 provides additional security. This degassing process is quite slow and can last several hours with a low rotation speed of the rotating container 3. When it has been completed, the valve 50 is switched and the level detector 58 is lowered through the valve so that the weight 67 arrives at the bottom of the neck 56. The volume between the vacuum pump 75 and the sheath 8 is perfectly sealed vis-à-vis the outside and deprived of any atmosphere. The direction of rotation of the motor 5 is then reversed, so that the powder is gradually displaced downstream and thus passes inside the downstream mouth 25 before

  to fall into the hopper 26 and then into the sheath 8.

  The vibration generator 57 is simultaneously switched on

  running to promote the packing of the powder.

  Portholes may be provided on the wall of the

  hopper 26 to check the powder transfer.

  When the neck 56 of the sheath 8 also begins to fill, the powder reaches the weight 67 and modifies the capacity of the circuit consisting essentially of the wires 62 and 64. The measurement box 63 makes it possible to note this modification. The engine is then stopped, the level detector 58 is reassembled and the neck 56 is crushed then sectioned a

  slightly above the powder level by a suitable tool.

  The sheath 8 thus hermetically closed is then detached from the table 7 and stored while waiting to subject it to pressing then replaced by a

  new empty sheath after unscrewing the flange 55.

  We will now describe in more detail

  the filling mode of the rotating container 3.

  The powder is initially contained in large volume containers called bures and referenced 80 (Figures I and 3). The bures have a generally cylindrical shape and end in a threaded mouth 81. As there is not, because of the enclosure 1, sufficient freedom of movement to effect manual transfer in good conditions, provision has been made first of all a turning system 82 consisting of a yoke 83 with, in its center, a threaded crown 84 which can be screwed around

the mouth 81.

  The two lateral branches 85 and 86 of the yoke 83, on either side of the crown 84, are articulated to the two lateral branches 87 and 88 of an arch 89 of which the middle part 90 carries

a hoist hook hole 91.

  A funnel 92 is welded to the crown

  84 on the side opposite to that where the bure 80 is assembled.

  The funnel 92 is provided with a vibrator 93 and a tube 94 which corresponds to the end of a compressed nitrogen circuit not shown further. The tubing 94 enters through the funnel 92 and ends inside the bure 80 when the latter is mounted. A valve 95 is disposed between the end

  thinned funnel 92 and an annular rim 96.

  Once the bure 80 has been opened, the crown 84 is therefore screwed to the mouth 81, then a hoist hook 97 is engaged in the hole 91. The hoop 89 is raised as well as the yoke 83 and the bure 80. The hoist 98 is then moved on an overhead crane, not shown in its details, near the tilting container 6. During this transfer, the gravity forces maintain the

  bure 80 under the crown 84 and the funnel 92.

  The tilting container 6, detailed in the figure, is essentially formed by a funnel-shaped container 100 whose bottom 101, provided with support studs 99, is removable, and by a hoop 102 articulated on the funnel 100 by its two branches lateral 103 and 104 and the central branch 105 of which carries a hoist hook hole 106. The thinned end of the funnel 100, opposite the bottom 101, carries a valve 107 which ends in a neck 108 whose end 109 has a smaller outside diameter. An O-ring 110 is threaded around the end 109 in

stop against the shoulder.

  The tilting container 6 is supported at the start on a scale by the studs 99. The end 109 is therefore oriented upwards and the arch 102 rests

sideways on the scale.

  The bure 80, still suspended from the hook 97, is then turned over and engaged on the tilting container 6, the rim 96 coming to surround the end

  109. We find ourselves in the state shown in FIG. 3.

  The powder flows into the funnel 92 and from there into the funnel 100 as soon as the valves 95 and 107 have been opened. The vibrator 93 is turned on to promote flow by receiving the funnel 92, and nitrogen can be blown through the tubing 94

  in bure 80 also for this purpose.

  The scale allows the progressive filling of the funnel 100 to be measured. The valve 95 is closed when the required quantity of powder has been transferred.

filling a sheath 8.

  The bure 80 is then removed, turned over and set aside. The hoist 98 is brought close to the tilting container 6 and its hook 97 is slid into the hole 106 after closing the valve 107. When the arch 102 has been hooked, the tilting container 6 can be lifted, approached the rotating container 3 and then tipped over. The plug 28 is removed and the end 109 engaged in the orifice 27; the seal 110 is then compressed between the latter and the shoulder of the neck 108. The valve 107 is then opened to fill the rotating container 3. A vibrator 111 fixed to the funnel 100 can here again be used to facilitate decanting . The bottom 101 can be removed if necessary to facilitate the total emptying of the tilting container 6 by putting it in the open air. The plug 28 once replaced, the above detailed degassing and filling process of

sheath 8 can begin.

Claims (9)

  1. Sheath powder filling machine (8), characterized in that it comprises a powder container (3) rotating under the action of a motor (5) about an axis (4), the container being provided with an emptying orifice (23) with a vacuum pump (75) and a filter (24) permeable to gases and impermeable to powder, with an orifice for introducing (27) powder, and a powder discharge port (25), a pipe (9) joining a sheath (8) and the powder discharge port (25), and a helical system of fins (29) for deflection in the   rotating container (3) and around the axis (4).   2. Sheath powder filling machine according to claim 1, characterized in that it comprises an oven (31) which surrounds the rotating container (3). 3. sheath powder filling machine according to claim 2, characterized in that the oven consists of two half-shells (32)   separable and likely to be assembled.   4. Sheath powder filling machine   according to any one of claims 1, 2 and   3, characterized in that it comprises a flexible connection (51) disposed between the pipe (9) and the sheath (8), as well as a vibration generator (57) integral with the sheath (8).   5. Sheath powder filling machine   according to any one of claims I to 4,   characterized in that it comprises a valve (50) disposed on the pipe (9) and communicating the sheath (8) either with the rotating container (3), either with a pump (53).   6. Sheath powder filling machine   according to any one of claims 1 to 5,   characterized in that it comprises an intermediate container (6) intended for the transfer of powder to the rotating container (3), the intermediate storyteller (6) being provided with an orifice (108) comprising a valve (107) and can be attached to the filling orifice (27) of the rotating container (3), as well as a tilting arch (102), hookable to a hoist (98).   7. sheath powder filling machine according to claim 6, characterized in that it comprises a nozzle (92) provided with connecting means (84) to a container (80) in which the powder is stored before being transferred into the intermediate container (6), the nozzle further comprising a valve (95) and an orifice (96) which can be attached to the orifice   (108) of the intermediate container (6).   8. sheath powder filling machine according to claim 7, characterized in that   the nozzle is provided with a vibrating generator tions (93).   9. sheath powder filling machine according to claim 7 or 8, characterized in   that the end piece (92) is funnel-shaped.