Hello dear readers and homemade products!
Those of You who have designed any serious CNC machines know very well that they need high-quality cooling. In particular, this applies to solid-state and gas laser modules , CNC machine tool spindles , and other very hot powerful elements. Of course, active air cooling is ineffective in these cases, and liquid systems have to be used.
In a simple version, the liquid cooling system is a single circuit with two heat exchangers. The advanced version implies the use of another circuit – a compressor refrigeration unit. The result is a so-called “chiller”, widely used in industrial conditions.
Igor, the author of the YouTube channel “igorkawa”, has created a very complex and precision CNC machine that requires high-quality cooling of the spindle. In this article, the wizard will tell you how he made a combined refrigeration unit (chiller) for cooling the spindle of a CNC machine.
The main task of such an installation is to maintain the spindle temperature at 26 ° C ± 2 ° C. Due to the high cost of the CW-5000AG chiller ($ 650), as well as its dimensions, the master decided to make its analogue on his own. The total cost of the components was about $ 150.
Materials required for homemade products.
– Digital thermostat STC-1000
– Fan AC 220V
– Power supply 24V 2A
– Diaphragm pump for reverse osmosis
– Aquarium heater
– Compressor GTK80AT, condenser FNHM-003
– Water flow sensor YF-S401
– Filter drier
– Copper tube, stainless steel sheet, wires
– Silicone tubes
– Anaerobic adhesive (clamp threads)
– Welding wire.
Tools used by the author.
– Welding machine.
Overview of system elements.
For heat exchange of refrigerant with air, such a condenser FNHM-003 is used .
A new Soviet-made fan will blow air through the condenser fins. Of course, it is easy to replace it with a modern 220V fan of a suitable size.
The refrigerant will be R 134A freon, which will be pumped by the GTK80AT compressor.
To make a refrigerant evaporator, you need a ¼ inch (6 mm) copper tube 6 meters long.
You also need a cylindrical container for the water-freon heat exchanger. For this, a pipe with a diameter of 150 mm and a stainless steel sheet are suitable. There will be no internal pressure in the tank (open circuit), and the lid is removable.
A simple digital thermostat STC-1000 powered by 220V will maintain the temperature in the specified range and control the system components (heater and refrigerator). The device has terminals for connecting a power line, a temperature sensor, as well as two outputs for a refrigerator and a heater.
The diaphragm pump from the reverse osmosis system will pump water through the water circuit. It is powered by 24V, which will require a separate power supply with a current of about 2A .
Another important element in the water circuit will be the water flow sensor . Its working range of measurements is from 0.3 to 6 L/min.
You will also need stainless steel tubes, from which pipes will be made on the heat exchanger tank, as well as a tube for installing a temperature sensor.
The elements of the water circuit will be interconnected like this 8mm silicone tube . It is advisable to take a transparent tube – it will be more convenient to control the presence of liquid in the system.
First of all, Igor welds the bottom to the 150-mm pipe, forming a “bucket” for the water-freon heat exchanger. To weld stainless steel, a TIG welding machine with an inert gas supply is used.
Outside the tank, pipes for water supply and drainage are welded.
Also petals are welded to attach the container to frame, and a plate for installing the pump.
Now you need to make an evaporator for the refrigerant from a 6 mm copper tube. It is required to form a spiral from it with taps in the upper part.
To wind the spiral, the master uses a lathe with an aluminum round (diameter 110 mm) fixed in a chuck.
The end of the tube is hooked with a fabric tape on one of the cams. It is necessary to calculate in advance the length of the stocks of tubes for the formation of leads on one side.
Winding is carried out at low speed (the machine is equipped with a frequency regulator).
First, both leads are located on opposite sides of the spiral so as not to damage the tube during bending.
The second spiral lead is passed inside it, and the evaporator coil is ready. Of course, winding can be done not on a blank, but on a pipe, by putting one of the ends of the tube inside it.
Rubber rings are put on the ends of the tubes – they will be gaskets between the lid.
From a profile pipe the master made a frame on which all system components.
The compressor is installed first on the frame. Usually, the kit contains all the necessary fixtures and relays.
At the bottom of the” water “tank the coolant outlet is located.
A drain pipe is installed in the lid, as well as a pipe plugged in the lower part for installing a temperature sensor. Oil will be poured into the latter – this will provide good heat transfer from the liquid to the sensor, and low inertia of the readings.
The hole for the heater has not yet been prepared in the center of the lid.
The container is insulated from the outside with penoizol. Now you can attach it to the frame.
Two 90-degree bends are made on the side of the tank, a liquid level control tube is installed between them.
The evaporator coil is installed inside the tank. A membrane pump is attached to the plate.
< img class = "aligncenter" alt = "How to make a chiller (refrigeration unit) for CNC machine tools and not only" src = "https://usamodelkina.ru/uploads/posts/2021-05/1620908494_chil-105.jpg"/> anaerobic glue (thread lock)
As you can see, the author has already fixed an air fan on the condenser.
The master insulated the lower part of the copper spiral with tubes so that it would not come into contact with the bottom of the tank.
The refrigerant circuit is sealed and charged with freon.
< img class = "aligncenter" alt = "How to make a chiller (refrigeration unit) for CNC machine tools and not only" src = "https://usamodelkina.ru/uploads/posts/2021-05/1620908596_chil-137.jpg"/> Condenser refrigerant supply pipe.
After the condenser, the refrigerant flows through a filter drier and a capillary tube (3 m long) into the evaporator.
From the evaporator, the freon returns to the compressor.
Inside the tank, the master installed a 200W aquarium heater. It not only warms up the water to the required 26 degrees before starting the machine, but also protects the system at possible negative temperatures in winter.
To test the system, the master connected a copper spiral to the water circuit, and heats it up with a gas burner. At the same time, the automation is already working, and water is circulating in the system.
As soon as the liquid temperature reached 28 degrees, the automation turned on the compressor and the fan.
After a few minutes, the temperature rise stopped.
In order not to burn oxygen in the workshop, the burner was replaced with a heating coil. After a while, the temperature stabilized at 26-27 degrees, which is what is needed.
But the chiller is already in place under the machine.
A slide from two corners allows it to be almost completely extended for service.
Actually, the CNC machine itself, for which all this was done.
< img class = "aligncenter" alt = "How to make a chiller (refrigeration unit) for CNC machine tools and not only" src = "https://usamodelkina.ru/uploads/posts/2021-05/1620908538_chil-213.jpg"/> You may be interested in:
– Water-cooled CNC spindles
– Cloudray CO2 lasers
– Solid state laser modules .
I thank Igor for the details of designing a refrigeration unit for machine tools.
Good mood, good health, and interesting ideas to everyone!
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Author's video can be viewed here. There, on the channel, you can also find the rest of the series of videos about making a CNC machine from granite slabs.
Hello dear readers and homemade products!