American Whitney created a horizontal milling machine in 1818.
In order to mill the spiral groove of the twist drill, American Brown created the first universal milling machine in 1862, which is the prototype of the elevator milling machine.
The gantry milling machine appeared around 1884.
In the 1920s, semi-automatic milling machines appeared, and the workbench used the stoppers to perform automatic conversion of “feed-fast” or “fast-feed”.
The gantry milling machine, referred to as gantry milling, is a milling machine with a gantry frame and a horizontal long bed.
On the gantry milling machine, the surface can be machined simultaneously with multiple milling cutters. Processing accuracy and production efficiency are relatively high. Suitable for flat and beveled surfaces for large workpieces in batch and mass production.
CNC gantry milling machines can also process space surfaces and some special parts.
The shape of the portal milling machine is similar to that of a planer. The difference is that the beam and the column are not equipped with a planer holder but a milling cutter with a spindle box. And the reciprocating motion of the longitudinal table of the gantry milling machine is not the main motion, but the feed motion, and the rotary motion of the milling cutter is the main motion.
The portal milling machine consists of a door frame, a bed table and an electrical control system.
The portal frame consists of a column and a top beam with a beam in the middle.
The beam can be moved up and down along the two column guide rails.
There are 1 or 2 milling heads with vertical spindles on the beam for lateral movement along the beam guides.
A two-stage milling head with a horizontal spindle can also be mounted on the two columns for lifting movement along the column guide.
These milling heads can machine several surfaces simultaneously.
Each milling head has a separate motor (up to 150 kW), shifting mechanism, steering mechanism and spindle components.
The horizontal long bed has a movable workbench and is covered with a shield.
During machining, the workpiece is mounted on the table and is then fed longitudinally.
There are also some variants of the portal milling machine to suit different workpieces.
① Gantry boring and milling machine
The beam is equipped with a milling and boring milling head. The main shaft (sleeve or ram) can be used for axial motorized feed and has a fine motion adjustment device. The fine adjustment speed can be as low as 5 mm/min.
Boring and milling operations are possible.
② Gantry drilling and milling machine
Drilling and milling operations can be completed by mounting a power head on the beam and loading the drill or milling cutter through the post.
The gantry milling machine bed is equipped with an X-axis guide rail, and the gantry milling machine table is fastened to the bed.
There is a gantry frame on the top of the workbench.
The gantry further includes: a gantry carriage, and the gantry carriage is clamped on the X-axis rail.
The Z-axis guide rail is mounted on the gantry.
A beam, the beam is provided with a Z-axis carriage.
The beam is movably clamped to the Z-axis guide by the Z-axis carriage. A Y-axis guide rail is also mounted on the beam.
The milling device of the gantry milling machine are arranged on the Y-axis guide rail, so that the gantry frame is subjected to three-dimensional space milling processing of X, Y and Z under the control of the numerical control system.
The CNC portal milling machine has high precision milling, drilling, boring and cutting operations.
(4) Main parameters
The main parameters of the portal milling machine are the width of the work surface, and the width of the gantry is also used as a parameter.
For example, CNC gantry milling with model SK2015-3 means that the gantry has a width of 1.5 meters and the working table has a length of 3 meters. In other words, it is capable of processing workpieces that are 1.5 wide and 3 meters long.
Classification of gantry type milling machine
(1) Divided by form
According to whether the gantry is moving, it is divided into a gantry fixed table mobile type (about 90% or more) and a gantry mobile type (also called bridge type).
The bridge type gantry milling is characterized by a small footprint and a large carrying capacity. The gantry travels up to 20 meters, making it easy to machine long or heavy workpieces.
According to whether the beam moves on the column, it is divided into two types: moving beam type and fixed beam type; the beam moving on the elevated bed is called overhead type.
(2) Divided by system
It is divided into ordinary type and CNC type. There are also manufacturers to develop digital intelligent gantry milling with ordinary milling and CNC milling – one button conversion, which is more flexible and practical.
(3) Divided by capability
It’s divided into light, medium and heavy (super heavy) gantry milling.
The gantry milling machine has sufficient rigidity, high efficiency, convenient operation, simple structure and comprehensive performance.
The specific performance characteristics vary according to the type, model and manufacturer, and have a lot to do with the technology used.
Taking the SK series three-axis CNC gantry milling mentioned above as an example, its performance characteristics are:
- The vertical milling head is equipped with TX400 heavy-duty gantry milling head, double rectangular guide rail, with strong rigidity;
- Milling head mounted ball screw, pneumatic broach device, servo motor drive;
- The side milling head is equipped with a V5 gantry milling head with an independent lubrication device. The lifting is driven by an ordinary reducer, and the frequency control is adopted;
- Universal milling/CNC milling one-button conversion three-axis CNC system, which can be programmed and operated manually by the expansion panel, which is extremely implementable in the actual machining process;
- The bed is advanced and retracted, the beam is up and down, and the vertical milling head is equipped with a Taiwan ball screw, which is driven by a servo motor;
- With timing belt and synchronous wheel;
- Hand-held electronic handwheel unit for easy three-axis tool setting;
- Unique beam lifting safety interlocking device to ensure the repeatability of the machine tool;
- The station standard cycloid pump group is continuously lubricated with low failure rate.