US3516646A

US3516646A - Mixer with mixer drum equipped with mixing blades located on a central drive shaft

Info

Publication number: US3516646A
Application number: US678947A
Authority: US
Inventors: Paul Stift
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-10-30
Filing date: 1967-10-30
Publication date: 1970-06-23
Anticipated expiration: 1987-06-23

Description

June 23, 1970 P. STIFT 3,516,646

MIXER WITH MIXER DRUM EQUIPPED WITH MIXING BLADES LOCATED ON A CENTRAL DRIVE SHAFT Filed Oct. 30, 196' 2 Sheets-Sheet l r w. 1 x V 4% 2 F/ 17 I K. All l l5 lnvenfor PAU\ 81TH" June 23, 1970 sTlFT 3,516,646

MIXER WITH MIXER DRUM E UIPPED WITH MIXING BLADES LOCATED ON A CENTRAL DRIVE SHAFT Filed Oct. 30, 1967 2 Sheets-Sheet 2 A War? UEXJ United States Patent MIXER WITH MIXER DRUM EQUIPPED WITH MIXING BLADES LOCATED ON A CENTRAL DRIVE SHAFT Paul Stift, 15 Markgrafenstn, 1 Berlin 28, Germany Filed Oct. 30, 1967, Ser. No. 678,947

Int. Cl. B28c /10 US. Cl. 259-178 2 Claims ABSTRACT OF THE DISCLOSURE Mixer with a drum containing mixing blades near the bottom and located on a central drive shaft, with the blades serving to conduct the material along the bottom and sides of the container towards the top and then return it to the bottom. The shaft having the mixing blades mounted thereon is surrounded by a hollow sheath and the latter is mounted on the drum.

The invention relates to a mixer with a mixer drum containing mixing blades situated near the bottom of said mixer drum and located on a central drive shaft.

Mixers of this type, where the mixing blades conduct the material along the bottom and sides of the container towards the top and then return it to the bottom, are already known. With these mixers, the disadvantage exists that the rotating shaft driving the mixing blades propels the particles of the material to be mixed towards the outside as a result of the action of the centrifugal forces arising from this shaft. The particles of the material to be mixed are therefore prevented from returning to the bottom of the container. As a result of this, the process of mixing is impaired and particularly in the vicinity of the drive shaft, centrifugal dispersion of the particles of the material to be mixed causes air to enter from above in the direction of the shaft, i.e. the very air which, with a device constructed in accordance with the invention, is to be beaten out.

The invention aims at producing circumstances where the air forced outwards by the mixer at the bottom and the sides does not re-enter at the central shaft driving the mixing blades. The solution to this problem lies in accordance with the invention in an arrangement whereby the shaft bearing the mixing blades is surrounded by a hollow sheath arranged on the mixer drum in a manner known as such. As a result of the arrangement of the hollow sheath on the mixer drum, the said sheath remains fixed and the rotating shaft of the mixer is screened by said hollow sheath so that the rotary motion of the shaft cannot impair the process of mixing. Moreover, the hollow sheath surrounding the shaft also prevents air from entering the mixer from the top in the direction of the shaft. Thus pursuant to this solution and in accordance with the invention, the air contained in the material to be mixed is beaten out to an extent not previously achieved.

Devices for mixing liquids incorporating a shaft bearing mixing blades, said shaft being surrounded by a casing, are already known. This casing is provided to permit lubrication of the central shaft. The casing in a certain sense forms a lubrication bearing for lubricating the shaft driving the mixing blades. It is thus provided with an oil inlet and an oil level probe so that the oil level within 3,516,646 Patented June 23, 1970 the casing can be measured by means of the oil level probe in a manner similar to that encountered with motor vehicle engines. This known design is therefore quite different from the object of the invention.

The invention also provides for the possibility of incorporating a beating cross in the vicinity of the bottom of the drum at the lower end of the shaft projecting from the hollow sheath and also a transport blade situated above said beating cross at a distance from this cross. The beating cross and the transport blade are best fixed to a replaceable shaft adapter preferably designed in the shape of a truncated cone. A sealing device and a ball bearing system can also be incorporated at the lower end of the hollow sheath. A plain feather connection for interchangeable attachment of the motor which is situated above the drum can be incorporated at the upper end of the shaft. The hollow sheath can also be interchangeably suspended in the drum by means of a flange at its upper end.

FIG. 1 is a section view of the device; FIG. 2 is a bottom view of the adapter and FIG. 3 is a side view of the adapter.

At the upper end of the mixer drum 1 a ring 2 is Welded in- The flange 3 of the hollow sheath 4 lies on the ring 2. The hollow sheath 4 which may have an external shape matching the prevailing proportions surrounds the shaft 5 at a distance. The drive motor 5 which is provided with a flange 7 is situated above the shaft 6.

The three

flanges

2, 3 and 7 are connected together by means of the bolts 8 in such a manner that the

flanges

3 and 7 with the related parts 4 and 6 can be removed by simple operation of the screws 8 which can be screwed into the flange 2 fixed firmly to the drum 1.

The shaft 5 is detachably connected to the motor shaft end by means of the plain feather connection 9. Rotation of the shaft end 10 is transmitted to the shaft 5 via the plain feather connection 9.

A sealing device 11 and a ball bearing system 12 are incorporated at the lower end of the hollow sheath 4. The interior of the hollow sheath 4 is sealed off by the sealing part 11. The shaft 5 is rotatably suspended in the hollow sheath 4 by the ball bearing system 12.

A shaft adapter piece 13 is interchangeably incorporated at the lower end of the shaft 5 by means of a bolt 14 and a suitably tapered end of the shaft 5 fitting into a related socket in the adapter piece 13 as represented at 15. At the lower end of the shaft adapter piece 13 in the vicinity of the bottom 16 of the drum is incorporated a beating cross 17 and at a distance above this a transport blade 18.

The material to be mixed is introduced into the drum 1 through an opening which is not represented and is drained oif on completion of the process of mixing at the bottom of the drum.

With a mixer constructed in accordance with the invention it is possible to use normal gravel which may be taken directly from the building site, i.e. gravel which has not been screened into individual fractions, while still producing a concrete which meets the requirements as regards quality. Concrete mixed in accordance with the invention does not, as was hitherto necessary, need to be submitted to vibration treatment at the location of the application in order to provide further compression. Only a small amount of certain fractions of gravel must be added for the manufacture of concrete even if the gravel as mentioned above has not been previously screened. In addition to the advantages of designs or improvements pursuant to the invention, the wear and tear of parts which were previously exposed to exacting demands is less and such parts can be readily changed.

What is claimed is:

1. A mixer comprising a central drive shaft, a mixer drum containing mixing blades situated near the bottom thereof and located on the central drive shaft, the blades serving to conduct a material along the bottom and sides of the drum towards the top and then return it to the bottom of the drum, a hollow sheath surrounding the shaft which has the mixing blades mounted thereon and arranged on the mixer drum, means to support the blades and shaft in the mixing drum, an interchangeable shaft adapter mounted on an end of the central drive shaft and being in the form of a truncated cone, means passing centrally of the adapter for securing the adapter to the central drive shaft, and a beating cross secured on the truncated cone on an end thereof.

4 2. A mixer according to claim 1, in which a transport blade member is provided mounted on the truncated cone and spaced from the beating cross.

References Cited UNITED STATES PATENTS ROBERT I. JENKINS, Primary Examiner U.S. Cl. X.R.