Double screw disaerator

Abstract

 @ The system brings the product alternatively in feeding motion on two lines in contact with the counterposed walls of an envelope to centrally converge in the interspace between the pair of screws (9,10) side by side between their intercrossing spirals. The feeding system in a conduct, where a vacuum compartment is operating, avoids that the advancing product obstructs the conduct.

Description

[0001] The invention refers to a disaeration equipment for reducing the volume of powdery products permitting to lower the production costs, in particolar those of the packing material, of the storing areas, the transport ones and by increasing the speed of the outomatic machine manufacturing. The above equipment permits a particular employ in the manufacturing lines and can be combined with a dosing implement for automatic manufacturing and sacking machines. The equipment is capable of condensing powders with any degree of granulometry, smoothness and chemical composition and it employs an equipment for self-regulating vacuum and electrical con- rrol board for the automatic working and regulation. The compartment is structured in powder seal parts and can be easily disassembled for performing the inside cleaning.

[0002] In explicating versions, inside parts are foreseen in stainless steel with employ of sealed equipments, or in explosion-proof construction. In special executions, the employ is foreseen for using transport "con tainers" and of production unities in general. The exigency of disaeration equipments for powdery products corresponds to precise exigencies of reducing the costs of production and of a better conversation of products such as those in sealed packing. The proceeding consents a volume reduction variable from 20 to 80% according to the features of the product to be produced and can be employed in any production pro cess.

[0003] At present, equipments are used in which the powder is foreseen to be put into a cylindrical conduct where the feed motion if performed by means of a screw feeder and disaeration is obtained by compression thickening of the product against the cylindrical wall and suction effect carried out by a vacuum assembly using a suction pump. This proceeding has considerable employ limits and can be used with powders having low specific weight only such as antigarasites in general. The feed motion of the screw in the conduct, in fact, causes a thickening of the pow- _der with a "plug" effect which blocks the powder feed motion. The contrivance according to the invention permits to obviate this inconvenien ce and allows to operate with powders of any type whatever with variable granulcmetry and weight. This is possible thanks to the fact that a fee ding compartment for the power feeding of new conception, substantially characterized by a pair of screws fitted side by side and the spirals of which are intersecting each other in a conduct having simmetrical half-parts of containment. In this way, the fed material is brought in succes sion in the interspace between the intersected spirals. This avoids the thickening with continuous effect in the feed conduct wall and, therefore, permits the products transport phase for the disaeration purpose.

[0004] In the execution shown as an example of the proceeding, the positioning of the two shafts 2 and 3 is foreseen with pinions 4 and 5 connected by means of chains 6 and 7 to a motor variator 8. Two screws 9 and 10 are connected to these two shafts and after having crossed the vacuum case 11, they are sustained by the two supports 12 and 13 contained in the machine base 14. The two screws in the vacuum case inside are contained in two symmetrical half-parts 15 and 16, which form a total fee ding envelope of the powder. This envelope is structured according to po rous and metal layers for support. To operate the equipment, the powder product is introduced into the machine head and the screws 9 and 10 are started which transport it up to the unloading point 14. In the vacuum chamber 11, the air contained in the product is sucked, while the envelope structure formed by half-parts 15 and 16 prevent the products from been sucked with the air. The unloaded product appears compact and agglomerated. Essentially, the proceeding allow versatility of employ for all the production processes of powders in general because the double screw system permits the mechanical compaction of the product by means of a mechanical tamping and a continuous feeding transport. This is pos sible through the fact that the fed product, in contact with the outer walls of the feeding conduct, is put into the interspace between the two intersecting spiral screws.

[0005] In the not limiting execution form of Table 1, fig. 1 is the view of the disaeration plant in perspective view for employ condition, showing the vacuum assembly as an accessory and electrical control board. Fig. 2 is the longitudinal section view of the machine showing the double screw feeding compartment. Fig. 3 is the transversal section of the ma chine in correspondence vith the double screw to point out the section of the feeding compartment which brings alternatively the product forward in contact with the conterposed inside walls and with the interspace between the screw spirals. In practice, the particulars of execution, the shape and similar of the invention may vary, in an analogous way to the structuration of the feeding conduct, to the screw sizes and to the power of vacuum assembly. All elements are moreover liable to be replaced by other equivalent ones.

Claims

1) Double screw disaerator, characterized by the fact that it allows to operate with powders of any specific weight and granulometry what ever by means of a proceeding which brings alternatively into feeding the product on two lines into contact with the oounterposed walls of envelope to converge centrally in the interspace formed by the pair of screws one near the other between their intercrossing spirals. This feeding susten of the product in the conduct, where a compartment is operating for the vacuum, to allow the sucking effect, avoids that the obstruction in the product feeding should clop the conduct. This is permitted by the fact that the obstruction with effect continuity is avoided in the feeding conduct.

2) Double screw disaerator, according to the previous claim, cha- recterized by the fact that, in a version, a compartment has been foreseen which employs head 1 for positioning shafts 2 and 3 with pinion 4 and 5 connected to a motor variator 8 by means of two chains. To these two shafts, two screws 9 and 10 are connected which having crossed the vacuum case 11 are sustained by two supports 12 and 13 con., tained in the machine base 14. The two screws are positined in a conduct formed by two symmetrical half-parts 15 and 16. For operating the machine , the product in powder is introduced into the machine head and the two screws 9 and 10 are started which transport it to the unloading point 14. In the vacuum chamber 11, the air contained in the product is sucked and the product cane out from the point 14 compact and agglomerated.

3) Execution form of a disaeration compartment substantially as described and illustrated for the above spefied purposes.

Drawing