EP0508962A1

EP0508962A1 - Reduction unit for mixing machines of the crown wheel type

Info

Publication number: EP0508962A1
Application number: EP92830156A
Authority: EP
Inventors: Franco c/o Officine Piccini S.p.A. Coletti; Francesco c/o Officine Piccini S.p.A. Schiavoni
Original assignee: OFFICINE PICCINI SpA
Current assignee: OFFICINE PICCINI SpA
Priority date: 1991-04-09
Filing date: 1992-03-27
Publication date: 1992-10-14
Also published as: IT1244970B; ITRM910241A1; ITRM910241A0

Abstract

The invention relates to a reduction unit for mixing machines of the "crown wheel" type, said mixing machine being of the type that comprises a tank (1), at least one horizontal arm (2) rotateable about a central vertical axis (3) having at least one extremity projecting from said tank (1) and, at at least one extremity of said horizontal arm (2), an assembly of vanes (4) rotateable about a second vertical axis (5), the reduction unit comprising at least one motor (9), first motion transmission-reduction means (11, 12, 13, 14, 15) between said extremity of the central vertical axis (2) projecting from the tank and the axis (10) of the motor (9), such that a reduction of about 1:50 - 1:80 (preferably 1:70) is obtained, second transmission-reduction means (18, 19, 20, 21, 22, 23) arranged between the upper extremity of said central vertical axis (2) and the second vertical axis (5) of rotation of the assembly of vanes (4); a post (8) being provided about said central vertical axis (2), fixed on the lower side on the floor of the tank (1) and bearing, on the upper side, at least one element (18) of the second transmission-reduction means.

Description

The present invention relates to a reduction unit for mixing machines of the "crown wheel" type.
More particularly, the invention relates to a reduction unit purposely studied to be advantageously fitted on any type of mixing machine, either of a little or of a large capacity.
Usually, mixing machines provide a horizontal arm which rotates about a vertical axis and which provides, on at least one extremity, a system of vanes which rotate in a sense concordant with or opposite that of the arm, to obtain an optimum mixing of the mix.
This type of mixing machines, commonly said "crown wheel" mixing machines, usually has a large volume, from about 250 litres upwards.
This is mainly due to the fact that in most cases the reduction unit is extremely cumbersome, complex and, consequently, expensive.
Moreover, as the motor is arranged on the upper side, one has great maintenance problems due to the presence of great central torques.
Consequently, the solutions provided at present to obtain the "crown wheel" motion of the side vanes, besides turning out not very suitable even to large size mixing machines, render the adoption of this solution for smaller mixing machines practically impracticable.
At present, the smaller mixing machines (100 to 150 l) are realized with side vanes of a fixed or idle type, which, if on a hand limits the costs thereof, on the other doesn't allow an optimum mixing of the mix to be obtained.
In the light of the above, the advantages appear very apparent that turn out by being able to have at disposal a reduction unit like that suggested according to the present invention, which allows the "crown wheel" solution to be able to be adopted eventually on very small mixing machines too.
It is, in fact, the main object of the present invention to realize a reduction unit for crown wheel mixing machines that is of a very simple construction and very little cumbersome, so rendering the realization of a crown wheel mixing system practical and advantageous on any type of mixing machine.
A further object of the invention is to realize a reduction unit of the said type, that is realizeable at decisely limited costs.
It is still an object of the invention to realize a reduction unit that does not require a great maintenance by the user.
It is therefore the specific subject matter of the present invention a reduction unit for mixing machines of the "crown wheel" type, said mixing machine being of the type that comprises a tank, at least one horizontal arm rotating about a central vertical axis having at least one extremity projecting from said tank and, at at least one extremity of said horizontal arm, an assembly of vanes rotating about a second vertical axis, the reduction unit comprising at least one electric, hydraulic, explosion or diesel motor, first motion transmission-reduction means between said extremity of the central vertical axis projecting from the tank and the axis of the motor, such that a reduction of about 1:50 - 1:80 (preferably 1:70) is obtained, second transmission-reduction means arranged between the upper extremity of said central vertical axis and the second vertical axis of rotation of the assembly of vanes; a post being provided about said central vertical axis, inferiorly fixed to the floor of the tank and upperly bearing at least one element of the second transmission- reduction means.
According to a preferred embodiment of the reduction unit according to the invention, the extremity of the central axis projecting from the tank is the central one, the motor and the first reduction-transmission means being arranged below the tank itself.
Further, according to the invention, said first reduction-transmission means can comprise a first reduction-transmission, with a reduction of about 1:2 - 1:3, between the shaft of the motor and a third axis, and a second reduction-transmission between said third axis and the vertical central axis.
Preferably, the first reduction-transmission is made up of two wheels arranged respectively on the shaft of the motor and on said third axis, and of first mechanical means, such as a smooth or a toothed belt, a chain and a further gearwheel, which join them to each other; the second reduction-transmission, which will give a reduction ratio of about 1:20, will be made up of an oscillating reduction gear.
Still according to the invention, said first reduction-transmission means can be made up of an epicyclic reduction gear.
Still according to the invention, said second reduction-transmission means can be made up of a first gearwheel integral with said post and of a second gearwheel borne by said second axis, said first and second wheels being connected by second mechanical means.
According to the invention, the second mechanical means can be made up of chains and/or toothed or smooth belts and/or gearwheels, but preferably they are made up of two further gearwheels, rotateable about the fourth and the fifth axis borne by the horizontal arm, having sizes and characteristics analogous to those of the second wheel borne by the second vertical axis, and which mate with each other and with the first and the second gearwheel, respectively.
This solution allows to have the assembly of vanes rotating in the same sense of rotation of the horizontal arm.
Obviously, assemblies of vanes can be provided on both the extremities of the horizontal arm or on more horizontal arms, a corresponding number of second reduction-transmission means being provided in these cases.
The present invention will be disclosed now according to preferred embodiments thereof with particular reference to the figures of the annexed drawings, wherein:

Figure 1 is a side view, sectioned vertically, of an embodiment of the reduction unit according to the invention;
Figure 2 is a top view of the assembly of Figure 1, and
Figure 3 shows a detail of the assembly of Figure 1 in a vertical section.

Referring now to all the three figures of the annexed drawings, one can observe the tank 1 of a crown wheel mixing machine endowed with an arm 2, substantially horizontal, rotateable about a vertical axis 3.
An assembly of vanes 4, rotating about the axis 5, is provided at one extremity of said arm 2, again inside the tank 1, while a scraper 6 is provided at the other extremity of the arm 2.
A further scraper element 7 is provided, borne by the arm 2, in proximity to the post 8 fixed on the bottom of the tank 1 and in the interior whereof the axis 3 is arranged.
In the following a preferred embodiment will be disclosed of the reduction unit according to the invention which allows the motion of the horizontal arm 2 and that of the assembly of vanes 4 to be obtained.
A motor 9 is arranged below the tank 1 of the mixing machine.
The transmission of the motion of the shaft 10 of the motor to the axis of rotation 3 of the arm 2 is realized through a system of trapezoidal belts 11 which mate with a first pulley 12, borne by said shaft 10, and with a second pulley 13 borne by a further axis 14.
A first reduction in the ratio of about 1:2-2,5 is obtained.
The axis 14 is borne by a reduction gear 15 of the oscillating type, known in the literature.
The reduction member 15 is characterized by a good resistance and by an extreme ease of application, in that it mates with the tank 1 simply by means of an adjustment tie rod 16 and it is directly borne by the axis 3.
Inside the reduction gear 15 a system for transmitting the motion from the axis 14 to the axis 3 is provided. The reduction of the motion that is obtained is of about 1:20.
So the reduction of the speed of the motor up to the value whereat one wants to make the arm 2 to rotate (about 20 revolutions per minute) has been obtained.
As already mentioned, the axis 3 rotates inside a spost 8 fixedly arranged on the bottom of the tank 1.
A wheel 18 is rendered integral with the upper extremity of the post 8, through the interposition of a flange 17 welded to the post 8 itself.
Two vertical axes 19 and 20 are provided on the arm 2, which bear two gears 21 and 22, arranged on the same plane of the wheel 18, to transfer the motion of the arm 2 to a further wheel 23 keyed on the axis 5 of the assembly of vanes 4.
The two gears 21 and 22 have the only end to transfer the motion, while the reduction is due to the ratio between the wheel 18 and the wheel 23.
The interposition of two gears 21 and 22 between the wheels 18 and 23 allows to have the rotation of the wheel 23 in a sense concordant with the sense of rotation of the arm 2.
It is apparent how the reduction unit according to the invention can be fit for the case in which two assemblies of vanes 4 on both the extremities of the arm 2 are provided too.
The providing the motor 9 below the tank 1 is much more practical under many viewpoints. In fact, in such a way it is possible to open the tank by the upper side. Moreover, one has a much more limited encumbrance and one has a greater ease of loading and cleaning.
However, it turns out to be apparent how the suggested solution can be realized, if desired, also providing the motor 9 above the tank 1, or with the installation of two motors 9, one below and the other above the tank 1 simultaneously.
The present invention has been disclosed with specific reference to some its preferred embodiments, but it is to be understood that variations and/or modifications can be made by those skilled in the art, without so departing from the scope of protection thereof.

Claims

A reduction unit for mixing machines of the crown wheel type, said mixing machine being of the type that comprises a tank, at least one horizontal arm rotateable about a central vertical axis having at least one extremity projecting from said tank, and at at least one extremity of said horizontal arm, an assembly of vanes rotateable about a second vertical axis; the reduction unit being characterized in that it comprises at least one motor, first motion transmission-reduction means between said extremity of the central vertical axis projecting from the tank and the axis of the motor, second transmission-reduction means between the upper extremity of said central vertical axis and the second vertical axis of rotation of the assembly of vanes; a post being provided about said central vertical axis inferiorly fixed to the floor of the tank and upperly bearing at least one element of said second transmission-reduction means.
A reduction unit according to Claim 1, characterized in that the extremity of the central axis projecting from the tank is the central one, the motor and the first transmission-reduction means being arranged below the tank itself.
A reduction unit according to Claim 1 or 2, characterized in that said first reduction-transmission means comprise a first reduction-transmission, arranged between the shaft of the motor and a third axis, and a second reduction-transmission arranged between said third axis and said vertical central axis.
A reduction unit according to Claim 3, characterized in that said first reduction-transmission is made up of two wheels arranged, respectively, on the shaft of the motor and on said third axis, and of first mechanical means which join them to each other.
A reduction unit according to Claim 4, characterized in that said first mechanical means are made up of a smooth or a toothed belt, of a chain or of a further gearwheel.
A reduction unit according to one of Claims 3 to 5, characterized in that said second reduction-transmission is made up of an oscillating reduction gear.
A reduction unit according to one of Claims 1 or 2, characterized in that said first reduction-transmission means are made up of an epicyclic reduction gear.
A reduction unit according to one of the preceding claims, characterized in that said second reduction-transmission means are made up of a first gearwheel, integral with said post, and of a second gearwheel, borne by said second axis, said first and second gearwheels being connected by second mechanical means.
A reduction unit according to Claim 8, characterized in that said second mechanical means are made up of chains and/or toothed and/or smooth belts and/or gearwheels.
A reduction unit according to Claim 8, characterized in that said second mechanical means are made up of two further gearwheels, rotateably arranged on a fourth and a fifth axis of rotation borne by said horizontal arm, having sizes and characteristics analogous to those of the second wheel borne by the second vertical axis, so as not to create a reduction of the motion, and which mate with each other and with the first and the second gearwheel, respectively.
A reduction unit according to any one of the preceding claims, characterized in that two assemblies of vanes are provided arranged on both the extremities of the horizontal arm.
A reduction unit according to one of Claims 1 to 10, characterized in that three horizontal arms are provided arranged at 120°, each one bearing an assembly of vanes, a corresponding number of second reduction-transmission means being provided.
A reduction unit according to one of claims 1 to 10, characterized in that one or more motors are provided of the electronic, hydraulic, explosion or diesel type.