Cooling bladder assembly for mixing mill

Cooling-bladder assembly for installation around the mixing chamber of a sandmill or the like is provided having a pair of semi-circular bladder halves with inner and outer walls for defining an enclosure. Inlet and outlet ports connected to a suitable pump circulate coolant fluid through the enclosure, the bladder halves being secured together at the opposed vertical edges. Spacers in the form of hollow pipe section are connected to the inner and outer walls of the bladder for maintaining the integrity of the enclosure and for creating turbulence in the coolant fluid. A heat transfer or conductive paste may be applied to the outer wall of the mixing vessel or to the adjacent inner wall of the bladder to facilitate the transfer of heat from the sandmill mixing vessel to the bladder assembly.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an apparatus designed to mix various substances, 
normally liquids, and more particularly to a cooling bladder assembly for 
cooling the mixing chamber vessel. 
2. Description of the Prior Art 
A sandmill is a type of apparatus used for stirring and mixing various 
substances, for example, paints, clay/water mixtures, and the like, in 
which particulate material such as glass beads or shot is added to the 
liquid or slurry for breaking up and dispersing the components to be 
mixed. The shot or beads are then filtered out of the mixture for re-use, 
leaving the mixed substance. 
Such an operation generates substantial amounts of heat in the mixing 
chamber, the heat generated being deleterious both to the chamber assembly 
and to the mixture inside the chamber. Thus, most mills of this type have 
an integral cooling jacket surrounding the actual mixing chamber, through 
which water or other coolant is circulated. The jacket is permanently 
fixed to the mixing chamber and extends circumferentially around the 
chamber, normally encompassing the entire height of the chamber. This type 
of arrangement permits cooling of the inner chamber but affords no fine 
control of the cooling operation due to the continuity of the cooling 
jacket. Such fine control is desirable because the upper portions of the 
sandmill are normally hotter than the lower portions. 
In addition, should repairs to the mixing chamber or cooling jacket become 
necessary, the entire apparatus must be disassembled for repairs or 
replacement. The operation is generally difficult because of the integral 
nature of the mixing chamber and jacket. This arrangement also risks 
contamination of the solution being mixed should a crack occur in the wall 
of the mixing chamber during operation. Similarly, faults in the water 
jacket which can not be repaired, require the replacement of the entire 
chamber/jacket assembly. 
SUMMARY OF THE INVENTION 
It is, therefore, one of the principal objects of the present invention to 
minimize component wear in devices such as sandmills by providing a 
cooling bladder assembly in which coolant may be circulated to dissipate 
heat generated by the mixing operation. 
Another object of the present invention is to minimize downtime of the 
sandmill, the cooling provided by the present bladder assembly serving to 
permit essentially continuous operation of the mill between the loading 
and unloading of the chamber vessel. 
A further object of the present invention is to provide a cooling bladder 
assembly in which the bladder is easily and quickly installed around the 
chamber vessel and which may be quickly and easily removed should repairs 
to the vessel or the bladder be required. 
A still further object of the present invention is to provide a bladder 
assembly that can be installed without the need for special tools or 
training for the installers, and which is durable for providing a long 
service life. 
These and additional objects are attained by the present invention which 
relates to a cooling bladder assembly for installation around the chamber 
vessel of a sandmill or similar device, and having a pair of bladder 
halves, each being a semicircular enclosure with an inner and an outer 
wall, the enclosure receiving coolant fluid. Inlet and outlet port means 
are provided and connected to a suitable source of circulation for pumping 
the fluid through the bladder halves. The bladder halves are secured 
around the mixing chamber at the opposing vertical edges where suitable 
securing means are used to provide a substantially full enclosure around 
the mixing chamber. 
The bladder halves are normally composed of stainless steel and have spacer 
means disposed between the inner and outer walls for maintaining the 
integrity of the enclosure and for creating turbulence in the bladder. A 
heat-conductive paste will normally be applied to the mixing chamber to 
aid in heat transfer from the sandmill to the bladder. 
Various additional objects and advantages will become apparent from the 
below description, with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now more specifically to the drawings, and to FIG. 1 in 
particular, numeral 10 denotes generally a sandmill, which is a device 
used for stirring various substances, such as paint or clay/water slurries 
and the like. The sandmill is conventional in most respects and will not 
be described in detail; however, such devices generally include a power 
source or motor 12, a drive mechanism denoted generally by numeral 14, a 
solution mixing chamber 16, and a shaft 18 or other means which connects 
the drive mechanism to a mixing wand device or stirrer (not shown), 
disposed inside the mixing chamber 16. 
Prior art sandmills normally have a cooling enclosure or jacket which is 
integrally formed with the actual mixing vessel, being separated only by 
the chamber wall. A fault in either the mixing vessel or the cooling 
jacket requires the shutdown, dismantling, and repair of the entire 
mixing/cooling vessel. If the fault occurs during use, a batch of mixed or 
partially mixed material may also be contaminated and lost. 
The present invention avoids any such difficulties by virtue of its being 
added around the mixing vessel after assembly of the sandmill, and by its 
bladder-like construction. The bladders 18 of the present invention are 
self contained, each one having inner and outer walls, 20 and 22, 
respectively and inlet and outlet port means 24 and 26, respectively, for 
selective and individual control of cooling. 
Each bladder 18 essentially consists of two self-contained symmetrical 
mating halves, 28 and 30, which are secured together along the 
corresponding and opposed vertical edge portions, here designated as 42 
and 44, respectively. The opposite vertical edge portions 46 and 48, 
respectively, are secured in a similar manner, all having corresponding 
and opposed apertures 50 for receiving suitable securing means, such as 
bolts 52 and nuts 54. End portions 42 and 46 each have radially extending 
flanges 56 and 58 which receive the opposed end portions, facilitating 
assembly of the bladder. The inlet and outlet ports 24 and 26, 
respectively, may be connected to any suitable circulation device or pump 
59, the cooling fluid normally being water. A possible arrangement is 
shown in phantom lines in FIG. 1, with hoses or pipes connected to the 
ports. 
The invention will normally have an upper bladder assembly and a lower 
bladder assembly, depending on the height of the mixing vessel. Thus, as 
illustrated in FIG. 1, there are four, individual, enclosed bladders, two 
upper halves and two lower halves. This allows selective and economical 
cooling of the upper or lower portion of the vessel, the upper portion 
normally becoming hotter than the lower portion during operation of the 
sandmill. While described in upper and lower portions, the present 
invention may also be supplied as a single relatively long, bladder 
assembly, or the orientation may be horizontal, such refinements being 
considered as within and contemplated by the scope of this invention. 
The bladder assembly is normally constructed of a corrosion-resistant 
material, for example, stainless steel, and the individual halves are 
symmetrical with respect to one another. Thus, for assembly of the 
bladders, any two halves may be mated and with either end up. 
The circulation of water or other cooling fluid through the bladder 
assemblies, cools the mixing vessel and the contents therein, thereby 
prolonging the life of the vessel and protecting the charge therein. To 
facilitate the cooling process, a heat transfer or conductive paste 60, of 
any suitable type, may be applied to the outer circumferential surface 62 
of the mixing vessel or to the adjacent inner circumferential surface 64 
of the bladder. 
As shown in FIG. 3, a plurality of additional port means 70 may be cut or 
otherwise provided in the inner and outer walls of the bladder halves for 
accepting a thermocouple 72, or similar devices, and for promoting 
circulation of coolant through the bladder. 
The ports 70 are provided with spacer means 74, such as a pipe section, 
which is welded or otherwise secured to the inner and outer walls of the 
bladder. These spacers ensure the separation of the inner and outer walls, 
preventing deformation thereof, and also enhance coolant circulation due 
to the "spoiler" effect on the coolant flow path. The increased turbulence 
provides a further increase in cooling efficiency over prior art cooling 
jackets. The units are pressure tested upon final assembly before 
installation around the mixing vessel. 
The spaced locations of pipes 74 permit selective addition of conductive 
paste when desired to all sections of the chamber vessel wall and also 
allow the temperature to be checked at various levels during operation. 
The bladder assembly shown and described herein may also be provided with 
auxiliary cooling devices (not shown), to further cool (or warm) the 
circulating fluid therein. Such plumbing methods can provide various 
degrees of cooling efficiency, depending on the charge being mixed in 
vessel or chamber 16. 
Should a fault develop in either the mixing vessel or the present bladder 
assembly, the production run may normally be completed, with no damage to 
the charge in the mixing vessel. In sandmills with integral cooling 
jackets, a leak causes contamination of the product being mixed and/or the 
halting of the process for immediate repairs. The present bladder 
assembly, with the self-contained bladder members, avoids these 
difficulties since a leak in either component, the chamber or the bladder, 
does not affect the other, and the production run may be completed before 
repairs are made. 
With the present invention, repairs to either the mixing chamber or to the 
bladder are easily accomplished by simply removing the individual halves 
of the bladder assembly. Should a leak develop in one bladder segment 
only, it is possible to continue operation of the sandmill while repairs 
to the bladder segment are made, appropriate adjustments being made for 
the lack or reduction of cooling. This possibility did not exist with 
prior art sandmills due to the integral nature of their construction. This 
also reduces by approximately one-half the cost of a replacement chamber, 
should one be necessary, due to the separate nature of the chamber 16 and 
the bladder assembly. 
In the use and operation of the present cooling bladder assembly, heat 
conductive material may be applied to the outer wall of the mixing chamber 
vessel 16 or to the inner wall of the bladder halves. Any two, 
symmetrical, bladder halves are then moved into position around the mixing 
vessel, the end flanges 56 and 58 serving to help align the components. 
The sections are then secured together at the opposed vertical edges and 
the inlet and outlet ports are connected to a suitable coolant circulation 
system. 
The invention thus provides superior cooling performance in an arrangement 
that is more economical to manufacture and operate than prior art systems. 
Installation and removal are easily accomplished and the present bladder 
assembly provides a long service life for the mixing vessel and the 
bladder itself. 
While an embodiment of cooling bladder assembly for a mixing vessel and 
modifications thereof have been shown and described in detail herein, 
various additional changes and modifications may be made without departing 
from the scope of the present invention.