Wheeling, IL--Designing a paint mixer is simple, right? Hook a couple of belts to a big electric motor, attach a switch to turn on the power, then supply a mechanism to hold the cans while they shake.
If it's that simple, then try this: design a paint mixing machine that's simpler, faster, lighter, cheaper, safer, more efficient, more versatile, and easier to maintain than anything on the market. And, oh, don't forget that the machine needs a smaller footprint than its predecessor, as well as a mechanism to keep paint cans from crushing or sliding out during mixing.
That was the task facing mechanical engineer Margaret Lowan in the design of the MultiMix Gyro mixer, a new product from Fluid Management, Inc., A Unit of IDEX Corp. Based on feedback from focus groups, Fluid Management engineers knew customers wanted most or all of the features mentioned above on the company's next-generation machine. The engineers' response: a machine that weighs 32% less than its predecessor, costs at least 13% less than competing models, mixes paint approximately three times faster, uses 21% fewer parts, has a smaller footprint, handles a wider variety of paint viscosities, and incorporates multiple means to keep the most determined customers from misusing the machine.
Lowan and the technical staff at Fluid Management came up with the design via a concerted effort focusing on mechanical simplicity. Most of the electronics from previous machines were eliminated in favor of simpler, easier-to-maintain mechanical devices.
Innovations on the new machine include the following:
Engineers employed a single-stage drive (one motor), instead of a dual-stage drive, to rotate both of the mixer's axes. A poly-V belt links the motor to the main (horizontal) axis; a separate belt attaches the main axis to the secondary.
The speed ratio between the mixer's two rotating axes is optimized. Instead of using the more typical 1:1 ratio, engineers stepped down the speed of the main axis and boosted the speed of the secondary axis by changing pulley sizes. With the secondary axis operating at twice the speed of the main axis, the machine mixes paint about three times faster than previous versions.
Despite the machine's faster mixing rate, Lowan was able to reduce the motor size. The key: Employing a poly-V belt, instead of a standard V-belt, for the main pulley drive reduced friction. Working closely with Emerson Motor Co., engineers also incorporated a larger run capacitor in the motor to minimize current draw. The downsized motor enabled engineers to reduce the machine's footprint.
A set of telescoping shafts enables the machine to accept small or large paint containers without a corresponding increase in the machine's size. For a large container, the shafts pull out from one another; for a small one, the shafts nest inside each other. Result: a smaller footprint.
Engineers enhanced safety by employing an anti-rotation mechanism. When the machine's main door opens, a lever pushes a pin into a slot on the main axis pulley, which automatically holds the rotating mechanism steady during loading and unloading. Result: As long as the door remains open, the main drive won't rotate, thus reducing the chance of operator injury. Unlike other systems, users don't need to lock the drive into place; it happens automatically.
A mechanical linkage to the power lever locks the mixer's door in place when the drive operates. Previous systems employed a solenoid-based device to keep the door closed while the mixer runs. This system, however, achieves the same end without the solenoid. When the power lever is in the "on" position, the linkage automatically locks the door. And if the door is open, the power lever can't be moved to the "on" position.
A specially designed clamping mechanism allows the machine to accept various size cans, yet doesn't crush them or let them slide out during mixing. The key: Two plates moving up and down on guide rods and lead screws provide clamping action. Operators transmit torque to the clamping mechanism through a handle. Through purely mechanical means, the clutch plates automatically indicate when correct clamping pressure has been reached.
Using these and other mechanical techniques, Fluid Management engineers eliminated most of the electronics typically employed on such machines. As a result, they gained a significant side benefit: The machine can be rated as explosion-proof because it removes electronic systems from potentially hazardous areas. "It's very easy to think in terms of limit switches and solenoid valves," notes Price Hodson, manager of equipment engineering for Fluid Management. "It's a lot harder to do it mechanically. That's what is unique about this design."
Using mechanical systems also simplifies maintenance and reduces part count. The new machine incorporates 531 parts, compared to 674 on a previous version. And it weighs about 400 lb., compared to 590 lb. for an older version. "The whole idea was to make a faster, less expensive, easier to use mixer," says Lowan. "We've done that here."
Additional details…Contact Price Hodson, Fluid Management, A Unit of IDEX Corp., 1023 S. Wheeling Rd., Wheeling, IL 60090, (847) 465-6232
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