Portal milling machine optimal for working with especially large parts, whose dimensions exceed 3x2 meters. The portal CNC machine differs from its classical counterpart primarily in the presence of numerical control, displacement sensors, inclinations, and rotation speeds, which allows for greater productivity in the process. In addition, often the control system controls one universal spindle head, which copes with all operations; the spindle in such machines often has the function of turning and tilting, which adds 2 additional axes to the X, Y, Z axes. all operations into one technological program, which can be transferred for execution to the numerical control system of the machine.
Milling machines with a classical design have a single-cantilever structure of the machine frame, as a result of which such machines have some limitations in terms of dimensions, as well as the weight of the workpiece being processed; often the maximum allowable size is from 2 to 3 meters, and the weight is up to 3 tons. For processing large parts, a gantry frame design is required.
The design of the portal is based on two columns, on which the edges of the horizontal beam are fixed. The spindle head, together with the vertically located spindle, moves along the guides of the cross beam. In order to speed up processing, you can use not only one spindle, but several; for example, side consoles can have one spindle each.
In the case of single console machines, the movement of the object occurs in three directions (along the X, Y, Z axes), caused by the movement of the desktop. A portal milling machine allows you to move the table exclusively along the X axis. Quite often, experienced designers use a device with a fixed table, which is fixed in the foundation, for processing very large workpieces. In such a machine, the movement along the X axis is due to the portal, which is movable relative to the desktop and the ground.
Regardless of whether the machine has a movable table or portal, the processing of large workpieces requires a high load mode for the main spindle. Also, movements along the axes of the machine cause great efforts aimed at overcoming deformation and friction forces during operation. Therefore, if you want to ensure high machining accuracy, be prepared to perform a number of tasks that increase the overall rigidity of the machine structure, reduce friction and wear of structural parts that cool the machine during operation, etc.; the specific list of necessary work depends on the model of the machine.
Each machine in the DARXTON product catalog is distinguished by high-quality assembly and materials, which guarantees reliable operation and a long service life. The DARXTON online store offers to buy a portal CNC machine at the best price on the Russian market. The company is engaged in the supply of exclusively high-quality machines and components. The company's specialists check each machine before shipment to the buyer, the company bears all service obligations after the purchase of the goods.
There are a lot of similar stories on the net, and I probably won’t surprise anyone, but maybe this article will be useful to someone. This story began at the end of 2016, when my friend, a partner in the development and production of test equipment, and I accumulated a certain amount of money. In order not to just waste money (the business is young), they decided to invest in the business, after which the idea of \u200b\u200bmanufacturing a CNC machine came to mind. I already had experience in building and working with this kind of equipment, and the main area of our activity is design and metalworking, which accompanied the idea of building a CNC machine.
That's when the movement began, which continues to this day ...
Everything continued from the study of forums dedicated to CNC topics and the choice of the basic concept of the machine design. Having previously decided on the materials to be processed on the future machine and its working field, the first paper sketches appeared, which were subsequently transferred to a computer. In the environment of three-dimensional modeling KOMPAS 3D, the machine was visualized and began to acquire smaller details and nuances, which turned out to be more than we would like, some of which we solve to this day.
One of the initial decisions was to determine the materials processed on the machine and the dimensions of the working field of the machine. As for the materials, the solution was quite simple - it was wood, plastic, composite materials and non-ferrous metals (mainly duralumin). Since we mainly have metalworking machines in our production, sometimes a machine is required that would process materials that are quite easy to process quickly along a curved path, and this would subsequently reduce the cost of production of ordered parts. Based on the selected materials, mainly supplied in sheet packaging, with standard dimensions of 2.44x1.22 meters (GOST 30427-96 for plywood). Having rounded these dimensions, we came to the following values: 2.5x1.5 meters, the working space is definitely, with the exception of the height of the tool, this value was chosen from the point of view of the possibility of installing a vice and assumed that we would not have workpieces thicker than 200mm. We also took into account the moment if it is necessary to process the end of any sheet part longer than 200 mm, for this the tool travels beyond the dimensions of the machine base, and the part / workpiece itself is attached to the end side of the base, thereby processing the end of the part can take place.
Machine design is a prefabricated frame base from the 80th profile pipe with a wall of 4 mm. On both sides of the length of the base, profile rolling guides of the 25th size are fixed, on which a portal is installed, made in the form of three profile pipes welded together of the same size as the base.
The machine is four axial and each axis is driven by a ball screw. Two axes are located in parallel along the long side of the machine, paired by software and tied to the X coordinate. Accordingly, the remaining two axes are the Y and Z coordinates.
Why we settled on a prefabricated frame: initially they wanted to make a purely welded structure with embedded welded sheets for milling, installation of guides and ballscrew supports, but they did not find a sufficiently large milling-coordinate machine for milling. I had to draw a prefabricated frame so that I could process all the details on my own with the metalworking machines available in the production. Each part that was exposed to electric arc welding was annealed to relieve internal stresses. Further, all mating surfaces were milled, and later the fitting had to be scraped in places.
Climbing ahead, I want to say right away that the assembly and manufacture of the frame turned out to be the most time-consuming and financially costly event in the construction of the machine. The original idea with a one-piece welded frame bypasses the prefabricated structure in all respects, in our opinion. Although many may disagree with me.
I want to make a reservation right away that we will not consider machine tools made of aluminum structural profiles here for now, this is rather a matter for another article.
Continuing the assembly of the machine and discussing it on the forums, many began to advise making diagonal steel struts inside the frame and outside to add even more rigidity. We did not neglect this advice, but adding jibs to the design is the same, since the frame turned out to be quite massive (about 400 kg). And upon completion of the project, the perimeter will be covered with sheet steel, which will additionally connect the structure.
Let's now move on to the mechanical issue of this project. As mentioned earlier, the movement of the machine axes was carried out through a ball screw pair with a diameter of 25 mm and a pitch of 10 mm, the rotation of which is transmitted from stepper motors with 86 and 57 flanges. Initially, it was supposed to rotate the screw itself in order to get rid of unnecessary backlash and additional gears, but they could not do without them in view of the fact that with a direct connection between the engine and the screw, the latter would begin to unwind at high speeds, especially when the portal is in extreme positions. Given the fact that the length of the screws along the X axis was almost three meters, and for less sagging, a screw with a diameter of 25 mm was laid, otherwise a 16 mm screw would have been enough.
This nuance was discovered already during the production of parts, and it was necessary to quickly solve this problem by manufacturing a rotating nut, not a screw, which added an additional bearing assembly and belt drive to the design. This solution also made it possible to tighten the screw well between the supports.
The design of the rotating nut is quite simple. Initially, we selected two tapered ball bearings that are mirrored on the ball screw nut, after cutting the thread from its end, to fix the bearing cage on the nut. The bearings, together with the nut, fit into the housing, in turn, the entire structure is mounted on the end of the portal rack. In front of the ball screw, the nuts fastened the adapter sleeve to the screws, which was later turned on the mandrel in assembled form to give alignment. They put a pulley on it and tightened it with two lock nuts.
Obviously, some of you will be wondering - "Why not use a gear rack as a mechanism for transmitting movement?". The answer is quite simple: the ball screw will provide positioning accuracy, greater driving force, and, accordingly, less torque on the motor shaft (this is what I immediately remembered). But there are also disadvantages - a lower speed of movement and, if you take screws of normal quality, then the price, respectively.
By the way, we took ball screw screws and nuts from TBI, a fairly budget option, but the quality is appropriate, since out of the taken 9 meters of the screw, we had to throw out 3 meters, due to a mismatch in geometric dimensions, none of the nuts simply screwed on ...
As sliding guides, profile rail guides of 25 mm size, manufactured by HIWIN, were used. Mounting grooves were milled for their installation to maintain parallelism between the guides.
They decided to make the ball screw supports on their own, they turned out to be of two types: supports for rotating screws (Y and Z axes) and supports for non-rotating screws (X axis). Supports for rotating screws could be bought, since there were few savings due to in-house production of 4 parts. Another thing is with supports for non-rotating screws - you can’t find such supports for sale.
From what was said earlier, the X-axis is driven by rotating nuts and through a belt gear. It was also decided to make two other axes Y and Z through a belt gear, this will add more mobility in changing the transmitted moment, add aesthetics in view of installing the engine not along the axis of the ball screw screw, but to the side of it, without increasing the dimensions of the machine.
Now let's move smoothly to electrical part, and we will start with the drives, stepper motors were chosen as them, of course, for reasons of lower price compared to feedback motors. Two engines with an 86th flange were put on the X axis, on the Y and Z axes along an engine with a 56th flange, only with different maximum torque. Below I will try to provide a complete list of purchased parts ...
The electrical circuit of the machine is quite simple, stepper motors are connected to drivers, which, in turn, are connected to the interface board, which is also connected via the LPT parallel port to a personal computer. Drivers used 4 pieces, respectively, one piece for each of the engines. I installed all the drivers the same, to simplify installation and connection, with a maximum current of 4A and a voltage of 50V. As an interface board for CNC machines, I used a relatively budget option, from a domestic manufacturer, as indicated on the site, the best option. But I will not confirm or deny this, the board is simple in its application and, most importantly, it works. In my past projects, I used boards from Chinese manufacturers, they also work, and in terms of their periphery they differ little from the one I used in this project. I noticed in all these boards, one may not be significant, but a minus, you can only install up to 3 limit switches on them, but at least two such switches are required for each axis. Or I just didn't get it? If we have a 3-axis machine, then accordingly we need to set the limit switches in the zero coordinates of the machine (this is also called the “home position”) and in the most extreme coordinates so that in the event of a failure or lack of a working field, one or another axis simply does not out of order (simply not broken). In my scheme, I used: 3 limit sensors without contact inductive sensors and an emergency button "E-STOP" in the form of a fungus. The power section is powered by two 48V switching power supplies. and 8A. 2.2 kW water-cooled spindle, respectively connected through a frequency converter. Turnovers are set from a personal computer, since the frequency converter is connected via an interface board. Turnovers are regulated by changing the voltage (0-10 volts) at the corresponding output of the frequency converter.
All electrical components, except for motors, spindle and limit switches, were mounted in an electrical metal cabinet. All control of the machine is carried out from a personal computer, they found an old PC on an ATX form factor motherboard. It would be better to shrink a little and buy a small mini-ITX with an integrated processor and video card. With not small dimensions of the electrical box, all the components were hardly placed inside, they had to be placed close enough to each other. At the bottom of the box, I placed three forced cooling fans, since the air inside the box was very hot. A metal plate was screwed on the front side, with holes for the power buttons and emergency stop buttons. Also, on this overlay, a socket was placed to turn on the PC, I removed it from the case of an old mini computer, it’s a pity that it turned out to be not working. An overlay was also fixed from the back end of the box, holes were placed in it for connectors for connecting 220V power, stepper motors, a spindle and a VGA connector.
All the wires from the engines, the spindle, as well as the water hoses for its cooling, were laid in caterpillar-type flexible cable channels 50 mm wide.
As for the software, Windows XP was installed on a PC placed in an electric box, and one of the most common Mach3 programs was used to control the machine. The program is configured in accordance with the documentation for the interface board, everything is described there quite clearly and in pictures. Why exactly Mach3, but all the same, there was work experience, I heard about other programs, but did not consider them.
Specifications:
Working space, mm: 2700x1670x200;
Axes movement speed, mm/min: 3000;
Spindle power, kW: 2.2;
Dimensions, mm: 2800x2070x1570;
Weight, kg: 1430.
Parts list:
Profile pipe 80x80 mm.
Metal strip 10x80mm.
Ball screw TBI 2510, 9 meters.
Ball screw nuts TBI 2510, 4 pcs.
Profile guides HIWIN carriage HGH25-CA, 12 pcs.
Rail HGH25, 10 meters.
Stepper motors:
NEMA34-8801: 3 pcs.
NEMA 23_2430: 1pc.
Pulley BLA-25-5M-15-A-N14: 4 pcs.
Pulley BLA-40-T5-20-A-N 19: 2 pcs.
Pulley BLA-30-T5-20-A-N14: 2 pcs.
StepMaster v2.5 interface board: 1 pc.
DM542 stepper motor driver: 4pcs (China)
Switching power supply 48V, 8A: 2 pcs. (China)
Frequency converter for 2.2 kW. (China)
Spindle 2.2 kW. (China)
I seem to have listed the main details and components, if something is not included, then write in the comments, I will add it.
Machine experience: In the end, after almost a year and a half, we still launched the machine. First, we set up the positioning accuracy of the axes and their maximum speed. According to more experienced colleagues, the maximum speed of 3 m / min is not high and should be three times higher (for processing wood, plywood, etc.). At the speed that we have reached, the portal and other axes, resting on them with your hands (with your whole body), can hardly be stopped - rushing like a tank. We started testing with the processing of plywood, the cutter goes like clockwork, there is no machine vibration, but they also deepened by a maximum of 10mm in one pass. Although after going deep they began to shallower depths.
After playing with wood and plastic, we decided to gnaw on duralumin, here I was delighted, although I first broke several milling cutters with a diameter of 2 mm, while I was choosing cutting modes. Dural cuts very confidently, and a fairly clean cut is obtained, along the machined edge.
We have not tried to process steel yet, but I think that at least the machine will pull engraving, and for milling the spindle is rather weak, it is a pity to kill it.
And the rest of the machine perfectly copes with the tasks assigned to it.
Conclusion, opinion on the work done: The work done is not small, as a result, we are pretty tired, since no one has canceled the main work. Yes, and a lot of money invested, I won’t say the exact amount, but it’s about 400t.r. In addition to the cost of assembly, the bulk of the costs and most of the forces went to the manufacture of the base. Wow, how we messed with him. And the rest, everything was done as funds, time and finished parts came in to continue the assembly.
The machine turned out to be quite efficient, quite rigid, massive and of high quality. Maintaining good positioning accuracy. When measuring a square made of duralumin, 40x40 in size, the accuracy turned out to be + - 0.05 mm. The processing accuracy of larger parts was not measured.
What's next…: There is still enough work on the machine, in the form of closing the guides and ball screws with dust protection, sheathing the machine along the perimeter and installing ceilings in the middle of the base, which will form 4 large shelves, under the spindle cooling volume, storage of tools and equipment. They wanted to equip one of the quarters of the base with a fourth axle. It is also required to install a cyclone on the spindle to remove and collect chips from dust, especially if wood or textolite is processed, dust flies everywhere and settles everywhere.
As for the further fate of the machine, everything is not clear here, since I had a territorial issue (I moved to another city), and now there is almost no one to deal with the machine. And the above plans are not the fact that they will come true. No one could have imagined this two years ago.
In the case of the sale of the machine with its price tag, everything is not clear. Since it is frankly a pity to sell at cost, and an adequate price has not yet come to mind.
This is where I will end my story. If I didn't cover something, then write to me, and I will try to supplement the text. And the rest is shown in the video about the manufacture of the machine on my YouTube channel.
Often there is a need for milling large-sized workpieces (for example, body parts of machines and units). Such blanks, in addition to large sizes, also have a large mass, which makes their processing difficult. Portal milling machining centers are best suited for this kind of work. Gantry milling centers are available with sliding table and moving columns. Using the design of the machine with movable columns allows you to process larger workpieces with a smaller machining center.
Portal milling machining centers with movable columns are used for processing long and large workpieces. The traditional layout of such machines includes a fixed table and a longitudinally movable portal carrying a traverse with a transversely vertically movable headstock. Thus, the movement of the tool along the X axis is carried out due to the movement of the portal along the desktop, the movement of the tool along the Y axis is carried out due to the movement of the traverse with the spindle along the portal in the horizontal plane, the movement of the tool along the Z axis is carried out due to the movement of the spindle along its vertical axis.
On portal milling machining centers, the following types of work are performed: milling, boring, countersinking, drilling, cutting internal and external threads, trimming ends. To perform all these types of work without readjusting the machine, it is usually equipped with a large belt-type tool magazine. Tool change is usually carried out by a rotating traverse, which reduces the tool change time and, ultimately, reduces the processing cycle.
The DEG Group of Companies supplies high-precision portal milling machining centers from DMC (Korea) to the Russian and CIS markets, performs commissioning and post-warranty maintenance of equipment.
The full range of milling machines is in the corresponding section
Portal milling machines from IRLEN-ENGINEERING company are modern high-precision equipment with numerical control, designed for metalworking of medium and large parts mounted on a long movable table, using a wide range of end tools. The key operations that are performed on equipment of this type include:
- Milling of planes, ledges.
- Drilling, boring holes.
- Formation of grooves of complex configuration.
- Finishing the required areas.
The use of angular heads in portal milling machines during machining allows you to feed the working tool at an angle to the axis, which minimizes the need to rearrange parts. The movable long table also allows you to minimize equipment downtime and process products of different configurations in almost a single cycle.
Features of CNC Portal Milling Machines
The key features of this equipment include high precision and speed of machining of metal products in a fully automatic cycle. Significant spindle speed, rapid tool change, which requires a pause of no more than 13 seconds, as well as the ability to install several workpieces on the table, make this equipment effective in serial and small-scale production.
In addition, the presented CNC portal milling machines are characterized by the following features:
- Possibility to install a chain tool magazine with 40, 60 or 120 positions.
- Tool wear monitoring system.
- Part measurement system before and after processing.
- Optical system for positioning the moving parts of the machine relative to each other.
- Coolant supply system to the working area.
- Modern numerical control controller.
When ordering a CNC portal milling machine, you can specify which systems and additional equipment should be included in the package. This approach allows you to get the necessary functionality of the equipment at the best cost.
Favorable cooperation with the company "IRLEN-ENGINEERING"
If you need CNC portal milling machines for metal, contact IRLEN-ENGINEERING, and our specialists:
- They will help you choose the most optimal model of equipment and additional equipment.
- They will perform installation and commissioning at your production base.
- Provide timely maintenance and repair during the warranty and post-warranty period.
- Conduct the necessary training on the operation of the equipment.
- Provide supply of accessories and consumables.
In addition, we offer services for the development of control programs for CNC portal milling machines for metal. Thus, you can avoid significant expenses for maintaining your own specialist with the necessary qualifications.
Call our managers to get additional information about the characteristics of the equipment, clarify the cost of delivery and place an order.
* Prices for machines are indicated without VAT, including delivery to the buyer's factory, including installation supervision
Gantry vertical milling centers GR series
The HAAS gantry series includes 2 models: GR-510 and GR-712. Movement along the X, Y and Z axes for the gantry milling machine GR-510 is 3073x1549x279 mm, for the GR-712 machine it is 3683x2159x279 mm. Optionally, it is possible to increase the Z-axis travel up to 610 mm.
Work zone
The working table with a heavy workpiece remains stationary during the operation of the machine. The spindle with the cutting tool moves along the X, Y and Z axes. The portal has O-shape which adds rigidity and reliability to the machine. In the basic configuration, the machines have a protective fence of the working area, which protects the operator and his workplace from chips and coolant.
Also included in the basic package of machines:
- automatic tool changer for 10 positions;
- 8100 rpm spindle with 40 taper;
- aluminum table with a grid of threaded holes;
- CNC system with 15″ color screen and USB port.
As options for these machines are available:
- automatic tool changer for 20 positions;
- 15,000 rpm spindle with 40 taper;
- steel table with a grid of threaded holes;
- 4th axis control drive for working with rotary tables;
- a system of measuring wireless probes for binding the tool and the workpiece;
- increase in clearance along the Z axis by 152 mm;
- coolant supply system, etc.
Demonstration of the work of the portal milling machine with CNC GR-712
Comparison of CNC vertical milling gantry machining centers
| Options | CNC vertical milling centers of portal type | |
|---|---|---|
| Model | Haas GR-510 | Haas GR-712 |
| Maximum travel along the X axis, mm | 3073 | 3683 |
| Maximum movement along the Y axis, mm | 1549 | 2159 |
| Maximum travel along the Z axis, mm | 279 | 279 |
| Maximum distance from the table to the end of the spindle, mm | 343 | 343 |
| Minimum distance from the table to the end of the spindle, mm | 64 | 64 |
| Table length, mm | 3099 | 3658 |
| Table width, mm | 1346 | 1829 |
| Distance between columns, mm | 1575 | 2184 |
| Maximum load on the table (equal. distributed), kg | 2722 | 2722 |
| Spindle taper size | 40 | 40 |
| Maximum spindle speed, rpm | 8100 | 8100 |
| Maximum spindle power, kW | 11,2 | 11,2 |
| Maximum torque, kN | 65 | 65 |
| Maximum axial force, kN | 11,2 | 11,2 |
| Maximum idle feed rate, m/min | 53,3 | 53,3 |
| Maximum working feeds along the XYZ axes, m/min | 20,3 | 20,3 |
| Number of positions in the automatic tool changer, pcs | 10 | 10 |
| Maximum tool diameter (when neighboring positions are occupied), mm | 89 | 89 |
| Maximum tool weight, kg | 5,4 | 5,4 |
| Tool change time (average), sec | 5,7 | 5,7 |
| Positioning accuracy, mm | ±0.05 | ±0.05 |
| Repeatability, mm | ±0.025 | ±0.025 |
| Coolant tank volume, l | 360* | 360* |
| * option | ||
What does Abamet offer and how to place an order
The Abamet company can offer not only a machine tool, but also a cutting tool, technological and tool equipment, coolant, i.e. everything necessary for its successful work. Tools, equipment, coolant are selected based on the technological study of the received technical assignment. Our service department provides comprehensive operational support and high-quality warranty and post-warranty service.
To make a request for a CNC portal milling machine, please contact us by toll-free contact number 8-800-333-0-222 or send an application with technical specifications to the email address [email protected] website. You can also make a request using the feedback forms on our website or by contacting the representative office of Abamet in your region.
