US3928940A

US3928940A - Packaging machine

Info

Publication number: US3928940A
Application number: US446205A
Authority: US
Inventors: Gaston Fagniart
Original assignee: Boracier SA
Current assignee: Boracier SA
Priority date: 1973-03-02
Filing date: 1974-02-27
Publication date: 1975-12-30
Anticipated expiration: 1992-12-30
Also published as: FR2219873B1; DK144237C; LU69390A1; GB1439581A; JPS5641483B2; DE2408504A1; BE811090A; OA04604A; FR2219873A1; JPS49135784A; NL7402773A; DE2408504C2; BR7401500D0; AU6621774A; CA998370A; IT1009696B; CH572841A5; AU474388B2; SE397322B; NL164240C

Abstract

Machine for packaging materials having a low mesh size, in cubic bags of flexible material. Each bag is supported in a rigidwalled cubic enclosure mounted on the door of an hermetically sealed filling chamber and a vacuum or controlled gaseous atmosphere is established and maintained in the filling chamber. The bag is vibrated and filled, under the controlled atmosphere, with the material to be packaged from which gas has been removed. The material falls under gravity from an hermetically sealed degassing and weighing chamber mounted above the filling chamber, passing through a tube into the bag. The neck of the filled bag is heat-sealed under vacuum in the filling chamber by two sealing heads. The sealed, filled bag is then removed from the filling chamber by opening the door and the bag is removed from the enclosure by a suction plate which grips one side of the bag. The bag can be inflated before insertion into the enclosure in order to produce its maximum volume.

Description

51 Dec. 30, 1975 United States atea; [1 1 Fagniart Attorney, Agent, or Firm-Robert E. Burns; Emmanuel J. Lobato; Bruce L. Adams Inventor: Gaston FagniartQValenciennes,

France ABSTRACT Machine for packaging materials having a low mesh [73] Assignee: Societe Anonyme dite: Boracier,

Switzerland Feb. 27

1974 size, in cubic bags of flexible material. Each bag is supported in a rigid-walled cubic enclosure mounted [22] Filed:

[21] Appl. No.: 446,205

on the door of an hermetically sealed filling chamber and a vacuum or controlled gaseous atmosphere is es- [301 Forelgn Apphcamm Prmnty Data tablished and maintained in the filling chamber. The

Mar. 2, France under the controlled atmosphere, with the material to be packaged from which bag is vibrated and filled,

gas has been removed. The material falls under gravity from an hermetically sealed degassing and weighing chamber mounted above the filling chamber, passing through a tube into the bag. The neck of the filled bag is heat-sealed under vacuum in the filling chamber by two sealing heads. The sealed, filled bag is then removed from the filling chamber by opening the door and the bag is removed from the enclosure by a suction plate which grips one side of the bag. The bag can be inflated before insertion into the enclosure in order to produce its maximum volume.

18 Claims, 8 Drawing Figures m mL n.n L m mm a .1 1 0 a TD 003 n ar fi ye.l RBVB 00004 3555 9999 llll 27 111 60 3 5840 6 6 8 8834 3238 55 6 2222 US. Patent Dec. 30, 1975 Sheet 1 of6 US. Patent Dec. 30, 1975 Sheet20f6 3,928,940

US. Patent Dec. 30, 1975 Shae; 3 of6 3,928,940

Fig.3

w 4 g 5 F 2 4 Q In f w 030 MP W 0 4 1L1: P w No l .0 3 3 9 L. "L w 2 US. Patent Dec.30, 1975 Sheet40f6 3,928,940

US. Patent Dec. 30, 1975 Sheet 50f6 3,928,940

Sheet 6 0f 6 I US. Patent Dec. 30, 1975 Fig.8 I

PACKAGING MACHINE BACKGROUND OF THE INVENTION This invention relates to packaging materials of low mesh size in bags of flexible material. It relates to a machine for such packaging.

Pulverulent or granulated products, such as cements, lime, sugar, flour and granulated plastics material are normally packaged either in paper, plastics or plasticized jute bags etc. in the case of small amounts (less than lOkg.), or in vessels made of metal, reinforced plastics or reinforced concrete, such as containers or silos, in the case of greater amounts.

Likewise, the transportation of these finely divided products takes place either in bags for small amounts or finely divided amounts or in vessels made of metal or possibly reinforced plastics for larger amounts. In the latter case, whether they are conveyed by road, rail, waterway or sea, the vessels are generally permanently mounted on specialized transportation appliances.

Finally, as concerns handling, the latter is tedious and expensive in the case of small amounts (trans-shipping bags) and generally takes place for products which are packaged or conveyed in bulk, in vessels or silos, either by gravity or by pneumatic means such as compressed air.

The traditional manner of dealing with these products produces numerous drawbacks. Within the field of packaging, these drawbacks are the very expensive necessity of putting the products into bags, or storage and ensilage installations, as well as the very reduced possibility of storage, or even preserving certain products such as quicklime. In the field of transportation, traditional methods require considerable investment in containers as well as a specialization of the transportation equipment. Finally, in the field of handling, one is frequently forced to handle large finely divided quantities, which is clearly more logical.

To obviate these drawbacks, it has been proposed to place the product to be packaged in an enclosure of plastics material in which a vacuum has been created and to displace the load formed in this way by means of a nozzle placed on the upper side of the load and connected to a vacuum-pump.

This known method which has numerous advantages with respect to previous methods, particularly as regards simplification of handling and improving condi tions for preserving oxidizable products, nevertheless has drawbacks when it is carried out.

Whereas it is relatively easy to create a partial vacuum in a plastics enclosure containing a material with a large mesh size, for example gravel, by means of a pump directly connected to this enclosure, it is indispensable to interpose a filter when the material packaged has a low mesh size.

Moreover, in this case, the time required for creating the vacuum does not make it possible to envisage an economical industrial exploitation. Indeed, the dura tion of the operation depends on the volume to be packaged and on the pressure drop undergone by the evacuated air, this pressure drop being particularly dependent on the dimensions of the inter-granular spaces. In the case of a material having a low mesh size, these dimensions are very reduced and even tend to decrease as the value of the vacuum increases, under the action of atmospheric pressure exerted on the walls of the enclosure.

In addition, it is difficult to obtain with this known method, enclosures having sides which are sufficiently large and sufficiently flat for gripping by means of a nozzle under good conditions. When this known method is applied, it is indispensible to use a sheet of very flexible plastics material as the enclosure, in order that this enclosure may deform when the vacuum is established in the material which it contains, causing a decrease in volume occupied by the latter; the enclosures obtained have numerous surface irregularities which are all the more troublesome since the gripping nozzle must bear against a large surface when the load to be handled is considerable.

It is a general object of the invention to remedy these drawbacks by new means for packaging materials of low mesh size under vacuum.

SUMMARY OF THE INVENTION According to the invention there are provided means for packaging materials having a low mesh size, and particularly packaging them in large quantities, in bags of flexible material, by:

a. pressing at least one part of the periphery of each bag against flat rigid walls;

b. establishing and maintaining a vacuum inside the bag;

c. subjecting the bag to vibrations;

d. filling the bag under vacuum with the material to be packaged, from which gas has been previously removed; and

d. sealing the full bag under vacuum.

The new machine comprises:

- flat rigid walls defining an enclosure open at at least its upper part, intended to serve as a support for the bag and for retaining at least one part of the periphery of the latter;

- means for imparting a vibratory movement to said enclosure;

a first chamber able to be closed hermetically,

containing the material to be packaged;

a pipe for discharging the material contained in the first chamber;

a second chamber able to be closed hermetically,

into which the discharge pipe opens;

-- means for maintaining a high vacuum solely in said first chamber or in both the two chambers;

at least one door for opening the second chamber, allowing introduction of the bag therein and to bring the neck of the latter under the discharge pipe; and

means for sealing the neck of the bag, provided in the second chamber.

Preferably each bag is inflated before filling to produce its maximum internal volume.

Packaging may also take place with a controlled gaseous atmosphere.

Since, according to the invention, gas is removed from the material to be packaged before the material is introduced into the packaging enclosure, the drawbacks caused by the removing gas from the material already placed in this enclosure are eliminated.

The packaging time itself is shorter, since the volume of gas to be eliminated is less.

In addition, the volume of material does not vary during its packaging and it is possible to give the packaging enclosure a well defined shape before filling, so that it has at least one flat face for gripping by the nozzle. For the same reason, it is thus possible to use containers which are lessflexible, thus thicker and stronger than the sheet of plastics material used in the known methods.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will now be described by way of example, with reference to the accompanying drawings in which:

FIG. 1 shows diagrammatically a perspective view of a packaging machine according to the invention, in its entirety;

FIG. 2 is a central, vertical, sectional view of a detail showing the positioning of a seal of a compressed air supply tube and members for gripping the neck of a FIGS. 3 and 4 are respectively a fragmentary end view and a fragmentary top view of another detail showing members for gripping the neck of the bag and of a device ensuring their correct positioning;

FIG. 5 is a half view in axial central section of a further detail, showing a telescopic connection of a discharge pipe, of movable hooks and of devices ensuring their correct positioning;

FIG. 6 is an axial sectional view of another detail, showing a weighing chamber for the material to be packaged;

FIG. 7 is a cross sectional view of still another detail, showing one of a pair of heat-sealing heads; and

FIG. 8 is an enlarged sectional view of the walls of the neck of the bag during the sealing along a cross-section of the sealing heads.

DESCRIPTION OF PREFERRED EMBODIMENT Bags 2 used for packaging material in accordance with the present invention have a shape such that they may be conveyed with reduced volume when they are empty. When they are full, they preferably generally cubic shape, as shown, and have at least one flat side enabling them to be gripped by a suction plate.

Good results have been obtained with substantially cubic bags 2 made from flexible polyethylene of 1 mm. thickness. This thickness is sufficient to make the bag impermeable to gases and to facilitate prolonged storage; it also provides good resistance to impact and to wear.

In order to facilitate handling of the bag by means other than suction plates, it is possible to provide one of its sides with a sunken ring located at the center of the side. Handling of the full bag by means of a ring of this type is enabled by the fact that the differential pressure created by the vacuum established in the bag applies a suction force to the walls of the latter. Around the ring, the wall of the bag has the function of a suction plate on the treated material, provided that it does not deform; to this end, the periphery of the ring is reinforced by an increased thickness of the wall of the bag.

In order to facilitate filling of the bags, an upper end of each'bag, as shown in FIG. 1 has a cylindrical neck 3 on a vertical axis, connected to the lateral faces of the bag by a surface in the form of a pyramid.

The bags, as shown, are hung from an endless cable 1, 4 by clips 5, each acting on the wall of a bag in the vicinity of the upper edge 6 of the neck 3 (see FIG. 1

Near the machine, each bag is manually detached in order to be subjected to an inflating operation intended to provide its maximum internal volume and to eliminate as far as possible the folds which may have formed on its outer surface and which could be detrimental to subsequent manipulation by a suction plate.

The neck 3 of each bag is engaged manually on the lower end portion 8 of a vertical tube 7 at the upper end of which a blower 9 blows in air. When the neck 3 and the lower end 8 are located in the necessary relative positions, a microswitch (not shown) causes inflation of an annular seal 10 placed around and secured to the tube 7, at its lower end 8 (see FIG. 2).

This seal 10, shown deflated in FIG. 2, bears against the inner wall of the neck which it keeps on the air supply tube 7.

The same air supply tube 7 is used to put each bag in position in the machine proper. To do this, the supply tube is mounted to slide on parallel guide bars 11 and 12 which make it possible to supply the bag above the machine and the lower end portion 8 of each tube 7 has telescopic, slidable fit with the tube itself to lower the bag into the machine.

The machine proper comprises two identical packaging chambers 13 and 14, surmounted respectively by chambers 15, 16. Each chamber l5, 16 is disposed for removing gas from, and for weighing, the material to be packaged. The packaging chambers 13, 14 are connected to the degassing and weighing chambers l5, 16 respectively, by vertical pipes 18,19 for discharging the material to be packaged.

The two packaging chambers 13 and 14 are located side-by-side in a single cylindrical enclosure 17 on a horizontal axis. They are separated from one another by a hermetic transverse partition 17', but are interconnected by a pipe 56 provided with a valve 57 whose purpose will be described hereafter. The two ends of the enclosure 17 may be closed hermetically by vertical circular closure means or doors 20 and 21, mounted on ball sockets sliding on horizontal steel bars 22 and 23, 24 and 25, and disposed to be moved along these bars by jacks such as 26.

As shown in FIGS. 1 and 4, each door, for example the door 20, is rigidly connected with a vertical basket or enclosure 27 whose inner dimensions are the outer dimensions of the cubic part of the bag and whose upper end is open, in order to facilitate the introduction of a bag 2 vertically, by means of the telescopic

air supply tube

7, 8 when the door 20 is open. It is the purpose of the basket 27 to retain the walls of the bag during the filling, in order to prevent the formation of folds which may be detrimental to subsequent gripping by means of a suction plate. In the vicinity of its base, each basket or enclosure 27 is provided with a vibrating table 92 intended to facilitate settling of the material in the bag 2 during packaging.

In a preferred embodiment of the machine, the basket 27 is also open at one of its side faces, for example the side 32, in order to facilitate the subsequent gripping of the filled and sealed bag by a device having a vertical suction plate such as 28. When the door 20 is closed, a vertical plate 29, mounted inside the chamber 13 on a horizontal jack (not shown) closes this open side 32 to ensure that the bag 2 is retained over its entire periphery.

FIGS. 3 and 4 show that the end closure door 20 is provided with a device intended to retain the neck of the bag while the bag is filled. In fact, this operation cannot be carried out by the telescopic tube 7, which must be extracted from the neck of the bag before closing the door 20 and after the seal 10 has been deflated.

The neck-retaining device comprises two

arcuate members

30 and 31 which, when they are in position, form a horizontal circular ring fitted on the upper edge 6 of the neck of the bag. Each arcuate member comprises a rib 34, which engages the edge of the neck 6 (see FIG. 2). An inflatable seal 35, fitted in the rib, bears against the latter, on the outside, in order to press it tightly against an edge 36 of the rib located inside the neck.

Each of the two

members

30 and 31 of the ring is integral with an oblique arm, 37 and 38, respectively, mounted to rotate about a vertical

cylindrical shaft

39 and 40 respectively, integral with a horizontal cross member 45 arranged parallel to the general plane of the door 20. A jack, 41 and 42 respectively, mounted to rotate, on the one hand, on a vertical pivot, 46 and 47 respectively, integral with the cross member and, on the other hand, on a cam integral with an arm, 43 and 44 respectively, makes it possible to control the movement of the

arms

37, 38 between their position retaining the neck 3 and their disengaged position schematically shown at 30a and 31a respectively. An abutment 48 and 49 respectively (shown in FIG. 4), integral with the cross member 45, limits the movement of the cam and makes it possible to obtain a predetermined position for retaining the neck accurately.

In order to facilitate engagement and disengagement of edge 6 with the groove of the

ring

35, 36 provided by the

members

30, 31, the cross member 45 supporting the

arms

37, 38 is able to move vertically under the action of a vertical jack 50 bearing, on the one hand, against the lower side of the movable cross member 45 and, on the other hand, against a second cross member 51 integral with the door 20. Guidance of the movable cross member 45 during this vertical movement is ensured by

shafts

39 and 40, extended under the cross member 45 and able to slide in vertical cylindrical apertures in the fixed cross member 51.

When the door 20 is closed, the bag whose sides are retained by the walls of the basket 17 and by the movable plate 29 and whose neck 3 is retained by the gripping

members

30 and 31, is placed in the filling position, the opening of the neck being located immediately below the pipe 18 for discharging the material to be packaged.

As shown in FIG. 5, the lower part of the discharge pipe 18 is provided with a telescopic tubular member 33, coaxial with the pipe 18 and mounted to slide vertically along the latter. The telescopic member 33 is engaged vertically in the neck 3 of the bag before filling the latter and makes it possible to prevent to a maximum losses of material to be packaged from the bag. The vertical movement of the member 33 is controlled by two diametrically opposed synchronised jacks, such as 52, acting between a fixed frame 53 and a ring 54 integral with the member 33. The ring 54 is guided in its vertical movement by vertical cylindrical rods such as 55, on which it is slidably mounted.

As aforementioned, the discharge pipe 18 connects the packaging chamber 13 to the chamber for removing gas and weighing. The two chambers may be separated by a hermetic valve 63 located in the discharge pipe 18 (see FIG. 6).

The chamber 15 for removing gas and weighing, with which its counterpart 16 is identical, is defined by a wall in the form of a vertical truncated funnel 58 surmounted by a vertical cylinder 59 closed at its upper part by a cover 60.

A pipe 64 opening in the truncated funnel 58 of the wall, permanently connectes the inside of the chamber 15 and that of the chamber 16 to a source of vacuum 93, valves 65 and 66 making it possible to isolate either chamber in the case where only half the machine is to be used (FIG. 1). As noted above, the vacuum source 93 can be replaced by other means for maintaining a controlled gaseous atmosphere, for the packaging of certain finely divided materials.

Opening into the cover 60 is the lower part of a chute 61 which receives the material from which gas is to be removed and which is to be packaged, the chute 61 being able to be separated from the chamber 15 by a hermetic valve 62. In practice, it is appropriate to always keep the chute 61 full, in order that opening the valve 62, at the time of introducing material into the chamber 15, does not cause the simultaneous entrance of too great a quantity of air.

Inside the chamber 15, the raw material introduced through the valve 62 is collected by a vertical funnel 67, whose lower part is in the form of a cylindrical pipe 68 coaxial with the discharge pipe 18, closed by a valve 69.

The funnel 67 is mounted on a weighing machine of known type, not shown in FIG. 6, but shown diagrammatically by a dial 70 in FIG. 1. (and by a dial 71 in the case of the degassing and weighing chamber 16), this device making it possible to introduce into the chamber 15, then into the packaging chamber 13, through the intermediary of the valve 69 and valve 63, the quantity of material corresponding exactly to the quantity to be packaged in one bag. Various stages of this introduction will be described hereafter, at the same time as the operation of the entire installation.

Once the bag has been filled, it is sealed transversely under vacuum in the vicinity of its neck 3 by means of a device contained in the chamber 13 (the chamber 14 contains an identical device).

Previously, it is necessary to give the neck 3, which is originally cylindrical, a flattened shape in order for it to have two joined walls. For this, as indicated by FIG. 5, two hooks 72 which are diametrically opposed with respect to the axis of the neck are used, acting vertically in a plane which in this case is perpendicular to the plane of the jacks controlling the telescopic member 33 of the discharge pipe 18.

These two books, located in the vicinity of the lower part of the telescopic member 33 when they are stationary, move downwards at the same time as the latter under the action of two diametrically opposed jacks 73, each acting between the fixed frame 53 and a sleeve 74 sliding on a stationary vertical cylindrical rod 75; a vertical jack 76, which is stationary in this first descending stage of the hook, transmits the movement to the support for each book, for example to the support 77 of the hook 72. The support 77 is guided vertically during this movement by a vertical cylindrical rod 78 with which it is integral, said rod sliding vertically in the ring 54 integral with the telescopic member 33 and being integral with a sleeve 79 sliding on the rod 55 for guiding this same ring. The same is true for the second hook. Very accurate guiding of each hook is thus obtained.

Since the telescopic member 33 is fitted as well as possible inside the neck 3 of the bag, it is necessary to provide a vertical groove 80 in its wall for the passage of each hook 72.

At the end of the first stage of their descent, the hooks 72 are placed on the edge 6 of the neck 3, inside the latter, at the two ends of the diameter of the latter. They are interposed between the two

members

30 and 31 for gripping the neck (FIG. 4).

When the bag is filled, their action of preparing the neck 3 for sealing begins, after raising the telescopic tube 33 and disengaging the

members

30 and 31 for gripping the neck. Simultaneously, a horizontal jack 81, integral with the support for each hook, brings about the action of the hooks at a distance apart on the edge of the neck, whereas the second set of vertical jacks 76 causes a new downwards movement of the hooks, allowing them to remain on the edge of the neck.

The neck is sealed by two rectilinear sealing heads 82, located horizontally opposite each other, parallel to the two joined walls which form the neck 3 after preparation, i.e. parallel to the vertical plane in which the two hooks 72 act. These two heads, located at the upper part of the packaging chamber 13, inside the latter, are moved towards the neck by two jacks 96, (FIG. 1) acting horizontally below the level in which the hooks 72 act.

FIG. 7 is a cross section of one of the heads 82. Located inside a U-shaped longitudinal section 83, whose opening is directed towards the neck of the bag and insulated from this section by a heat-resistant material 84, is a longitudinal sealing strip 85. Provided inside the sealing strip 85 is a longitudinal electric resistance element 86, fixed by a longitudinal plate 87, made like the strip 85 from a good heat-conducting material.

The active part of the sealing strip 85 projects from the section 83 and it is provided, at the point where it is intended to come into contact with the material strip to be sealed, with a rod 88 of a material intended to 'transmit the heat necessary for sealing, whilst able to be readily detached from the sealed material, before coolmg.

In the case of a bag made from polyethylene of 1 mm. thickness, good results have been obtained using rods 88 of PTFE filled with a conducting material such as bronze, heated to the melting point of the film of polyethylene, namely 130 to 150C, the strips being applied under a pressure of the order of about 10 kg/cm Rods 88 firstly cause melting of the wall of the polyethylene, penetrating therethrough under the action of jacks 96. They have

contours

88a and 88b (FIG. 8) causing a flow of the melted material to promote thorough sealing, for example in the regions 101 of the two joined walls of the neck 3. The penetration extends for several dozen mm., then it is limited by longitudinal abutments such as 89, fixed laterally to the section 83. As they are sufficiently close to each other, they thus cause the sealing proper. An operating process of this type makes it possible to seal walls of great thickness.

An abutment plate 94 is interposed between the sealing strip 85 and the heat insulation 84 located at the base of the section 83, in order to distribute the stress on the insulation as well as possible. In addition, a sheet of shock-absorbent material 95, such as cellular rubber, is interposed between the base of the section 83 and the insulation 84 in order to prolong the sealing action by applying slight pressure after the abutments 89 have come into contact.

After sealing, the full bag which has been hermetically sealed may be placed in the open air. A valve, 90 and 91 respectively, FIG. 1, makes it possible to connect each packaging chamber 13 and 14 respectively, with the open air.

The machine described as an example is provided with a device for discharging full sealed bags. Located at the side of each packaging chamber 13 and 14 is a handling device comprising a suction plate. Each of these devices, for example the arrangement associated with the chamber 13, is composed of a support 97 on which is mounted a vertical suction plate 28, capable of rotating with respect to a vertical shaft integral with the support 97. The support 97 slides on two horizontal rails 98 and 99, perpendicular to the general direction of the guide bars 22 and 23 of the door 20. The arrangement is such that the suction plate 28 adheres against the side of the bag left free by the basket 27, when the door 20 is open. A horizontal jack 100 pivoted on the one hand on the frame of the machine and, on the other hand, on the support 97 of the suction plate, controls the removal of the latter with respect to the basket, the suction plate moving the bag. One rotation of the suction plate 28 thus makes it possible to move the bag to a point where it may be discharged by a known system.

The various stages of operation of the machine are as follows:

The bags 2, supplied by the supply chain 1, are manually unhooked in order to be fixed by their neck 3 on the lower end 8 of the vertical blowing tube 7. As above-described, a micro-switch located on the tube 7 causes the inflation of the seal 10 placed around the lower end 8 of the tube 7. This seal 10 bears against the inner wall of the neck, which it presses against the tube 7 throughout the period of inflation.

The bag is also retained by the seal 10 whilst being put in position in the basket 27 of the machine. As above-described, this positioning is effected by sliding the tube 7 on guide bars 11 and 12, this sliding bringing the bag above the basket 27, then by telescopic elongation of the lower part 8 of the tube 7, this elongation causing the downwards movement of the bag into the basket.

When the bag is in position in the basket, the jacks 41 and 42, acting on the

cams

43 and 44 respectively, bring about the positioning of the gripping

members

30 and 31 above the edge 6 of the neck 3 of the bag, the inner seal 35 being deflated. Then, the jack 50 brings about the downwards movement of the cross member 45 and thus the downwards movement of the two

members

30 and 31 which engage the edge 6 of the neck. The inner seal 35 of the gripping members is then inflated, retaining the neck in the stationary position. The seal 10 of the telescopic blowing tube 7 is then deflated and the tube 7 moved upwards.

The door 20 is then reclosed, by the action of the jack 26. With its closing movement it entrains the basket 27 and the bag which it contains, and the neck of the bag is placed directly below the lower part of the discharge pipe 18 at the end of this closure. The inner door 29 moved by a jack which is not shown, then closes the open side 32 of the basket 27 in order to retain the bag perfectly in the basket.

Since the second packaging chamber 14 is at this time under vacuum, if the two halves of the machine operate alternately, it is possible to open the valve 57, in order to counterbalance the vacuums in the two packaging chambers 13 and 14. This makes it possible to make a saving on vacuum, since it is nevertheless necessary to re-establish normal atmospheric pressure in the chamber 14 before opening it.

The telescopic connection 33 of the discharge pipe 18 then moves downwards, under the action of jacks 52 in order to engage in the neck 3 of the bag. Simultaneously, the two books 72 complete the first stage of their downwards movement underthe action of jacks 73 and are placed on the edge 6 of the neck.

The equalizing valve 57 is then closed. One then opens the valve 63 providing a connection between the packaging chamber 13 and the weighing and degassing chamber 15, which is always under vacuum due to the action of the pump 93. At this time, the finely divided material to be packaged contained in the funnel 67 has already been in the chamber 15 for a sufficient period of time to have been degassed: it is thus ready to be packaged.

The valve 69 is then opened and the material to be packaged drops into the bag, in a quantity predetermined at the time of weighing, which is carried out in the chamber 15, before opening the valve 63. The bag is filled quickly and without dust, owing to the vacuum and to the short gap separating the outer wall of the telescopic tube 33 from the inner wall of the neck 3'. During filling, a vibrator 92 is started up, which causes settling of the material in the bag and makes it possible to obtain flat faces which bear perfectly against the walls of the basket 27.

When the bag is full and the weighing funnel 67 is empty, the supply valve 69 and then the connection valve 63 are re-closed.

A new weighing operation may then be undertaken in the chamber 15, by opening the measuring valve 62 for connecting the chute 61 and the weighing funnel 67. The output of the supply devices for the chute 61 of material to be packaged is such that this chute is always full, whereby vacuum losses at the time of this introduction are minimal.

The full bag which is located in the chamber 13 is then sealed transversely. Prior to this, jacks 52 bring about an upwards movement of the telescopic tube 33, the seal 35 for the

gripping members

30 and 31 is deflated and these members are returned to their stationary position by the action of the jack 50, which causes their disengagement from the neck, then of the jacks 41 and 42, which act at a distance apart. It should be noted that the deflation of the seal 35 should take place by suction, since it is necessary to compensate the vacuum existing inside the chamber 13. Then, simultaneously, the vertical jacks 76 bring about the downwards movement of the hooks 72, whereas the horizontal jacks 81 bring about a pulling action of the hooks on the edge of the neck. The neck deforms and at the end of its preparation it is in the shape of two joined walls, which may then be sealed by means of the rectilinear heads 82.

As above-described, the two sealing heads 82 are brought together by jacks acting horizontally. In a first stage, they penetrate the wall of the neck of the bag by causing this wall to melt, until the abutments 89 are pressed against the wall. In a second stage, when the heads are sufficiently close to each other, the two joined walls are sealed.

Once the bag is sealed, it is easy to disengage the sealing heads 88 by the action of their control jack, the material used for their manufacture preventing any adhesion.

Since the package is sealed under vacuum, it is possible to re-establish atmospheric pressure in the chamber 13. Previously, for the purpose of economy, the equalizing valve 57 is opened to establish a first partial vacuum inside the chamber 14, whose operating cycle is alternated with that of the chamber 13. At the same time,

vertical jacks

73 and 76 bring about the return of the hooks 72 to their upper position, whereas horizontal jacks 81 cause them to return to their position in grooves of the telescopic tube 33. When the vacuums between the two chambers 13 and 14 have been compensated, the equalizing valve 57 is re-closed, then the valve 91 for connecting the chamber 13 to the outside air is opened.

After having retracted the inner door 29, one may then proceed to open the door 20 by the action of the jack 26. On opening, the door 20 pulls the basket 27 and the full sealed bag towards the outside.

The jack then causes the translation of the suction plate 28 towards the full bag, the suction plate bearing against the free side of the latter. A vacuum is established between the suction plate 28 and the wall of the bag against which it is applied, a jack lifts the arrangement, then the support 9'7 of the suction plate is returned to its original position by means of the jack 100. The suction plate 28 is then caused to rotate on its support to a new position 28a in order to bring the bag into the discharge region; atmospheric pressure is reestablished between the suction plate 28 and the bag, which is released.

All the operations are accomplished virtually without any production of dust. In fact, supplying the weighing chamber takes place by suction of the material to be packed, thus without the production of dust and filling of the bag also takes place as above-described.

The abovedescribed operation according to the invention makes it possible to keep losses to a minimum. In addition this operation has proved particularly advantageous in the case where it is intended to pack products having a very low mesh size, or toxic products, whose packaging by known methods is dangerous for the operators.

With a machine of this construction, it is possible to achieve a filling rate of up to one bag per minute. In principle, the two halves of the machine are designed to operate simultaneously, but separate automation is provided for each of them, in order that they may accomplish their operating cycle: separately.

I claim: 1. A machine for packaging finely divided material, comprising;

support means for supporting and laterally confining a bag of flexible material, said support means comprising flat rigid walls defining an enclosure open at at least its upper part, to prevent deformation of the bag when the bag is filled with divided material;

means for defining a first chamber, for sealing it tightly and for receiving therein the material to be packaged in the bag; a discharge pipe for discharging the material received in the first chamber from that chamber; means for defining a second chamber and for sealing it tightly, and into which chamber the discharge pipe opens;

means for maintaining a controlled gaseous atmosphere selectively in said first chamber for treatment of the material received therein, and in both chambers for controlled filling of the bag;

closure means for supporting the support means, for

enabling introduction of the support means and of the bag thereon into the second chamber, and for positioning a neck of the bag under the discharge 1 1 pipe to enable filling of the bag, in the controlled gaseous atmosphere, with finely divided material previously treated by exposure to such atmosphere in the first chamber; and

means in the second chamber for sealing the neck of the bag pursuant to the filling of the bag.

2. Packaging machine according to claim 1, further including means for inflating the bag before its introduction into the enclosure.

3. Packaging machine according to claim 2, in which the means for inflating the bag comprise:

a supply tube for compressed air insertable in the neck of the bag; and inflatable annular seal means surrounding the tube for engaging the inner side of the neck of the bag;

said tube being telescopic and having means for telescopically sliding a lower end portion thereof into said neck.

4. Packaging machine according to claom 1, in which the first chamber comprises means for weighing the material received therein.

5. Packaging machine according to claim 1, in which the first chamber is located above the second chamber and the discharge pipe has .valve means for enabling controlled descent of the material by gravity from the first chamber to the second, in said atmosphere.

6. Packaging machine according to claim 1, in which the discharge pipe comprises a telescopic, lower end portion and means for introducing the latter into the neck of the bag to facilitate filling the bag.

7. Packaging machine according to claim 1, in which the second chamber comprises means for retaining the neck of the bag during filling, in predetermined position relative to the discharge pipe.

8. Packaging machine according to claim 1, in which the support means for the bag is integral with the closure means of the second chamber.

9. Packaging machine according to claim 1, in which the second chamber comprises means for retaining the neck of the bag, during filling, in predetermined position and wherein the support means for the bag is integral with the closure means of the second chamber, the means for retaining the neck of the bag during filling comprising arms, each pivoted at one of its ends, on an inner face of the closure means, and means for gripping the neck of the bag on the other end of each arm.

10. Packaging machine according to claim 9, in which each of said arms has an arcuate rib thereon and an inflatable seal located in said rib and engageable with the neck, the arms having means for positioning 12 the rib, relative to the neck to enable and control the engaging of the seal with the neck.

11. Packaging machine according to claim 1, in which the second chamber comprises means for deforming the neck of the bag into a pair of flat joined walls.

12. Packaging machine according to claim 11, in which said means for deforming the neck of the bag comprise two hooks disposed on either side of the discharge pipe, means for introducing said hooks into the neck of the bag, and means for moving said hooks symmetrically away from the discharge pipe, with portions of the edge of the neck engaged by the hooks, to prepare the neck for sealing.

13. Packaging machine according to claim 1, in which said means for sealing the neck of the bag comprise two heatable head means for heat sealing sheets of synthetic plastic material to one another; means for pressing said heated head means in mutually opposite directions against either side of the neck of a bag, of synthetic, plastic material; heat-conductive, low-adhesion rod means on each head means for contact with the neck of the bag, and abutment means for limiting the pressing of the head means against the neck and the resulting depth of penetration of the head means into the neck.

14. Packaging machine according to claim 13, in which each rod has a contour having a contour portion projecting from the rod, whereby, when the two rods penetrate into the neck of the synthetic plastic bag to be sealed, flowing of melted plastic material is produced, relative to the projecting contour portion.

15. Packaging machine according to claim 8, further including means for horizontally ejecting the bag from the support means after filling and sealing of the bag, said support means having a lateral opening for facilitating the ejecting of the bag.

16. Packaging machine according to claim 15, in which the second chamber has inner door means for closing the lateral opening of the support means.

17. Packaging machine according to claim 1, further including an additional subcombination, similar to the first-mentioned one, of a first chamber, a second chamber, a support means, a discharge pipe, a closure means and a sealing means, for filling another bag; and valve means for interconnecting the two second chambers to equalize and control the maintaining of a controlled atmosphere in said two second chambers.

18. Packaging machine according to claim 1 in which the means for maintaining a controlled atmosphere comprises means for maintaining a high vacuum.

Claims

1. A machine for packaging finely divided material, comprising; support means for supporting and laterally confining a bag of flexible material, said support means comprising flat rigid walls defining an enclosure open at at least its upper part, to prevent deformation of the bag when the bag is filled with divided material; means for defining a first chamber, for sealing it tightly and for receiving therein the material to be packaged in the bag; a discharge pipe for discharging the material received in the first chamber from that chamber; means for defining a second chamber and for sealing it tightly, and into which chamber the discharge pipe opens; means for maintaining a controlled gaseous atmosphere selectively in said first chamber for treatment of the material received therein, and in both chambers for controlled filling of the bag; closure means for supporting the support means, for enabling introduction of the support means and of the bag thereon into the second chamber, and for positioning a neck of the bag under the discharge pipe to enable filling of the bag, in the controlled gaseous atmosphere, with finely divided material previously treated by exposure to such atmosphere in the first chamber; and means in the second chamber for sealing the neck of the bag pursuant to the filling of the bag.

3. Packaging machine according to claim 2, in which the means for inflating the bag comprise: a supply tube for compressed air insertable in the neck of the bag; and inflatable annular seal means surrounding the tube for engaging the inner side of the neck of the bag; said tube being telescopic and having means for telescopically sliding a lower end portion thereof into said neck.

5. Packaging machine according to claim 1, in which the first chamber is located above the second chamber and the discharge pipe has valve means for enabling controlled descent of the material by gravity from the first chamber to the second, in said atmosphere.

10. Packaging machine according to claim 9, in which each of said arms has an arcuate rib thereon and an inflatable seal located in said rib and engageable with the neck, the arms having means for positioning the rib, relative to the neck to enable and control the engaging of the seal with the neck.