GB2068758A

GB2068758A - Foundry mould sand mixing machine

Info

Publication number: GB2068758A
Application number: GB8040681A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-12-18
Filing date: 1980-12-18
Publication date: 1981-08-19
Also published as: FR2471807B1; DE3047250A1; IT8026750A0; IT1134784B; GB2068758B; FR2471807A1

Abstract

A mixing machine comprises a rotary agitator (1) located in a cylindrical casing (2) and drven by a motor and reduction gear (26), the casing (2) at least partly containing a sleeve (6) made of low friction co-efficient and resilient material. Spaced from the inner surface of the casing this sleeve and the casing along at least part of its length is formed as two longitudinally divided hinged doors there being an annular chamber between both parts of the sleeve and the backing parts of the casing doors. Further, the rotary agitator (1) and the output shaft (25) of the motor and reduction gear (26) are interconnected by a mechanism (27, 30) which opposes their axial and rotational disengagement. <IMAGE>

Description

SPECIFICATION Foundry mould sand mixing machine This invention relates to a foundry mould sand mixing machine, that is to say a machine which has been designed for the preparation of foundry sand for the various processes of manufacturing of cores and moulds from sand and resins.

The machine which is proposed is of the kind comprising an agitator which turns at high speed inside a cylindrical casing, the mixer itself, in order to homogeneize the sand, which is supplied in known doses by a hopper, together with the necessary resin fed by an injector.

At present, this type of machine has two drawbacks: Firstly, the sand-resin mixture causes a coat or "crust" inside the cylindrical casing, which hinders the motion of the agitator.

Secondly, the high speed of the agitator and the strain it is subjected to in order to stir the components of the mixture, causes the agitator shaft to suffer a torsion effect with an unfavourable repercussion on the coupling of the agitator shaft to the power output shaft of the operating motor.

Thus, one object of the invention is to avoid the nuisance of a constantly and progressively coat or "crust" forming inside the cylindrical casing.

Another object is to provide a coupling system for the shaft of the agitator and the power output shaft of the operating motor such as to ensure a reliable and perfectly aligned connection between them.

According to the invention it is firstly proposed to provide in the cylindrical casing a sleeve which occupies, inside the casing, only that area where physical union of sand and resin occurs. Otherwise expressed, this sleeve will not occupy that part of the interior of the cylindrical casing in which there flows only the sand coming from a supply hopper.

The sleeve establishes with respect to the inside surface of the cylindrical casing an annular chamber.

The sleeve, which would be made, for example, of teflon, is elastically deformable when there is violent incidence of the agitator on any coat or "crust" to such extent that fragmentation of the coat or "crust" by fracturing will reliably occur.

Also according to the invention there is inserted along the shaft of the agitator a spigot having one conical and another cylindrical part, both adapted to equivalent surfaces of a quill connected to the motor shaft by means of an intervening resilient coupling.

The quill and the cylindrical end of the stem are diametrically traversed by a bore which is of progressively reducing width towards one end, this bore being intended to house a complementary, wedgelike part or cotter, acting in the sense of traction of the spigot and consequently of the agitator shaft towards the area of the resilient coupling. All this is in order to prevent any axial movement of the agitator and motor drive shafts.

In order to prevent relative rotation between the agitator shaft and the quill, a rigid mounting has been designed between the quill and that shaft. This comprises at least one pair of lugs which are actually prolonged parts of the quill itself and which adjust into open slots especially designed on a flange mounted around the spigot and welded to the agitator shaft.

In order that the characteristics of the invention hereinafter claimed, shall be clearly apparent reference is hereinafter made to the accompanying drawings of a presently preferred embodiment in which: Figure 1 is a side elevation partially in section, of that area of the cylindrical casing of a mixing machine wherein a teflon sleeve is fitted; Figure 2 is a cross section on line A - B of Fig. 1; Figure 3 is a longitudinal section of a quarter of the area of coupling of the agitator and the output shaft of the operating motor.

Referring now to the drawings, and more espe ciallyto Figures 1 and 2, there is shown a rotary bladed agitator 1 which is turned by a motor with speed reduction gear and is contained in a cylindrical casing 2 which receives sand from a hopper (not shown), as well as resin to be mixed with the sand from an injector 3, this injector 3 being placed in a more advanced position, towards the end of the cylindrical casing 2, than the dose-supplying sand hopper itself. Mixture of sand and resin occurs in that part of the casing 2 comprised between its end plane 4 and the plane 5. In parts of the cylindrical casing 2 comprised between planes 4 and 5, mentioned above, the agitator extends within a sleeve 6 made of teflon or similar material, this sleeve 6 being transversely divided into two parts.One extreme part7 is comprised between planes 4 and 8, in a way such that the part of the cylindrical casing 9 corresponding to the end part of the sleeve 7 and comprised, as has been said, between planes 4 and 8 is provided with the corresponding outlet 10 for the product once homogenized. The other part 6 of the sleeve comprised between planes 5 and 8 is related to two hinged doors 11 thus conforming to the part of the casing enclosing this part of the sleeve 6; this part of the sleeve 6 is divided longitudinally into two parts corresponding to the internal faces of the hinged doors 11 which conform to the corresponding portion of the cylindrical casing, having the especial characteristic that between the semiportions of the sleeve 6 and the hinged doors themselves 11, there is formed an annular chamber 12, which is repeated in the extreme portion 9 of the cylindrical body where the outlet 10 for the product is placed.

The corresponding semi-portions of the sleeve 6 are secured to the respective hinged doors 11 by means of screws threaded into the semi-doors 11 themselves and entering caps 13 provided in the chamber 12 itself functioning as separating elements for the semi-portions of the sleeve 6 and the hinged doors 11 themselves.

Thus arranged, and because of the semi-portions 6 of the sleeve related to the hinged doors 11 constituting the corresponding portion of the cylindrical casing where the mixture is produced, the coat or "crust" is thinner than the coat or "crust" formed in conventional mixing machines which lack such a teflon sleeve, although a coat or "crust" is also produced in the instant case though in lower proportion.

Thus, by virtue of the resilience of the material of which the sleeve 6 is made, the violent incidence of the agitator blades onto the coat or "crust" causes elastic deformation of the sleeve 6 to such extent that fragmentation by Fracturing of the coat or "crust" will inevitably be produced. The chamber 12 permits this resilient deformation of the sleeve 6 and as a result, as has been described, the fragmentation and subsequent fall of pieces of "crust" adhered to the sleeve 6, these pieces or fragments of the coat or "crust" are then mixed with the product composed of the resin and the sand, in away such that the violent turning of the blades causes grinding of the fragments.

On the other hand, a means for hinging of the doors 11 has been provided with the object of gaining access to the inside of the cylindrical casing itself for cleaning, these hinged doors 11 having the peculiarity of turning around a common hinge pin 14 placed longitudinally below the cylindrical casing itself, the hinge pin 14 being fixed at its ends into corresponding flanges 15 welded to the ends of the cylindrical casing 2 between which the hinged doors 11 are placed. In other words, the flanges 15 are welded to the cylindrical body 2 in the planes 5 and 8 already referred to.

These flanges 15 are joined at the top by means of two rods 16 running parallel in an horizontal plane.

Between the rods 16 are mounted prismatic pieces 17 into the ends 18 of which screws 19 are threaded and act as tightening elements for clamps 20 which exert pressure over the prismatic pieces 17 themselves and upon lugs 21 fitted to the exteriors of both swivel-mounted doors 11, these clamps having the peculiarity of being provided with elongated windows 22 which permit, upon loosening of corresponding screws 19 the movement of the clamps 20 and consequently the lowering of the hinged doors 11 as can be clearly seen in Fig. 2.

The hinge pin 14 of the doors 11 has inserted bushes 23 to which the doors 11 are connected by means of brackets 24 welded to the doors 11 and the respective bushes 23.

As already explained, by reason of the presence of the sleeve 6 placed along the part of the cylindrical casing in which the mixture of sand with resin takes place, the coat or"crust" which originates in the internal all of the mixer itself is easily removable and fragmented due to the inherent resilience of the teflon sleeve itself and finally ground, once removed, by the violent rotation of the blades of the agitator 1.

Moreover, as can clearly be seen in Fig. 1, it is arranged that the portion of the cylindrical casing comprised between the planes 5 and 8, that is to say, the portion corresponding to that formed by the hinged doors 11 presents a slightly larger diameter than the portion 2 of the cylindrical casing in front of the flange 15 welded in the planeS, all with the purpose of leaving perfectly aligned, that is to say with the same diameter, that portion of piping 2, when the sleeve 6 is placed inside the part of the cylindrical casing corresponding to the hinged doors 11, with the portion where the sleeve is placed 6.

The mode of coupling the rotary agitator 1 and the drive shaft 25 from the motor-reducer 26 is shown in Fig. 3 and comprises a spigot 27 inserted within the agitator 1 itself, this spigot 27 has a conical central portion 28 and two extreme end cylindrical parts, one in correspondence with the agitator shaft and the other 29 which is smaller in diameter. This part 29 together with the conical part 28 is complementary to the internal surface of a quill 30 which is connected to the shaft 25 of the motor reduction gear through an intermediate resilient coupling 31.

The smaller diameter part 29 of the spigot 27 as well as the quill 30 itself, has a diametric hole 32 of progressively reducing width towards one of its extremes, these holes being intended to accommodate a complementary part 33 in the form of a wedge which acts in the sense of traction of the spigot 28 itself and consequently of the agitator shaft 1 towards the area of the resilient coupling 31.

The quill 30 has notches of progressively diminishing diameter in the part coupling with the shaft 25, and the part corresponding to the resilient coupling 31 so that the resilient coupling 31 is augmented by a keyed-on arrangement 34 to ensure maximum safety in the coupling itself.

On the other hand, for the rigid coupling of the cylindrical portion 29 corresponding to the spigot 27 and the quill 30 itself, there is provided, as a complementary means of exerting pressure and tightening the piece 33 in the hole 32, a screw 35 threaded in the enclosing cap 36 provided to that effect in the area of the cotter 33.

With this coupling system, any movement along the axis of the agitator 1 and the shaft 25 of the motor reduction gear is avoided, since the cotter 33 prevents any such movement, whilst at the same time maintaining constantly under traction the spigot 27 as well as the agitator shaft 1 towards the area of the resilient coupling 31.

Finally, to prevent the agitator shaft 1 and the quill 30 from rotating relative to each other, a rigid seating has been provided between the shaft 1 and the quill 30. This is constituted at least by a pair of lugs 37 which are extensions of the quill 30 itself and which adjust into slots 38 open to that effect around the stem itself and welded to the agitator shaft 1. The result of all this is that the turning movement of the agitator shaft 1 with respect to the quill 30, is possible and relative once the lugs 37 are restrained in the mentioned open slots 38 and thus with respect to the shaft 25 itself of the motor and speed reduction gear 26.

Claims

1. Afoundry mould sand mixing machine intended for the preparation of sands for the various processes of manufacturing of cores and moulds from said sands and resins and comprising a rotary agitator driven by a motor and located, inside a cylindrical casing to which sand arrives from a hopper and the resin to be mixed with said sand, from an injector, characterized in that a part of the rotary agitator is co-incident with the axis of a sleeve made of teflon or like low friction co-efficient material, extending from the free end of the cylinder as far as beyond the area where the resin injector is placed; said sleeve being divided transversely in two parts: one at the extreme end where the outlet for the pro duct once homogenized is located and the other part of said sleeve being connected to two hinged doors which conform to the portion of the cylinder enclosing this part of the sleeve; said part of the sleeve being longitudinally divided into two parts corresponding to the internal faces of the two hinged doors, an annular chamber being thus established between both parts of the sleeve and the doors to which they are related, said annular chamber being repeated in the extreme portion of the cylindrical body where the outlet for the product is located, with the characteristic that the rotary agitator and the output shaft of the motor are interconnected by means of a mechanism which opposes their axial and rotational disengagement.

2. A foundry mould sand mixing machine according to claim 1, characterized in that the hinged doors rotate around a common hinge pin situated in the lower part of the cylindrical casing, said pin being rigidly mounted at its ends on flanges welded to the extreme ends of the cylinder between which the hinged doors are placed; said flanges being joined at the top with each other by means of two parallel rods in a horizontal plane and between the two axes of which, prismatic pieces are mounted, the front faces of said pieces having screws threaded therein to act as tightening means for exerting clamping pressure on the prismatic pieces themselves as well as on lugs externally fixed to both hinged doors.

3. A found mould sand mixing machine according to claim 2, characterized in that the hinge pin of the hinged doors carries bushes to which said doors are connected by means of welded brackets.

4. A foundry mould sand mixing machine according to any of claims 1 to 3, characterized in that the mechanism connecting the agitator and the output shaft of the operating motor comprises a spigot inserted in the agitator shaft, the spigot having a conical surface and another cylindrical surface which adjust to other equivalent surfaces inside a quill that is connected to the shaft of the motor by an interposed resilient coupling; both the quill and the cylindrical part of the spigot having a diametric bore intended to house a cotter pin.

5. Afoundry mould sand mixing machine according to claims 1 and 4, characterized in that in the front of the agitator shaft which receives a spigot, there is engaged a flange which presents two diametrically opposed slots into which there are fitted two lugs which are longitudinally prolongations of said front of the quill.

6. A foundry mould sand mixing machine constructed substantially as hereinbefore described with reference to, and as shown in the accompanying drawings.