Bar loader
A bar loader , as a loading magazine , short loader , loading magazine , bar magazine referred to. Or the like., A device, which bar material in various forms (. For example, round, square or hexagonal material) is a rotating machine or CNC lathe fully automatically feeds.
variants
There are different variants. The most common types are the so-called short bar loading magazine for bars up to approx. 1.6 m and bar loading magazines up to approx. 3.6 m. The most frequently used material shapes here are the round material, the square material and the hexagonal material. Other shapes and bar lengths are mostly served by special loaders.
Rod magazines long
technology
With bar loading magazines up to approx. 3.6 m (example image 1), the bar is moved from a material tray onto or into the guide channel. The material is now moved into the spindle with the help of the feed rod, which here has a collet that matches the shape and diameter of the material . The feed rod has clamped the material in the collet. Oil is fed into the guide channels. The rotation of the material by the spindle creates a hydrostatic guide due to the oil. Thus the material remains centric. The material is guided at both ends of the rod, on the one hand through the chuck and on the other hand through the feed rod .
Advantages and disadvantages
- Material length can be longer than the actual length of the CNC lathe spindle.
- Fewer bar changes are necessary than with short loading magazines.
- The delivered material is usually approx. 3 m long, so there is no need to saw the bars.
- High load on the spindle due to the additional load of the material mass
- Speed limitation, as the hydrostatic guide breaks off at too high speeds and no longer works.
- Mostly long set-up times.
- Since the material is carried in oil, the cooling lubricant is contaminated by oil that is carried into the machine.
- high space requirements and high weight of the bars with larger diameters
history
The bar loading magazines up to approx. 3.6 m were created from the bar feeders. In contrast to bar loading magazines, a bar feeder has the disadvantage that it cannot automatically reload material. Here, the operator had to manually add a new bar after each finished bar. At the beginning, a tube in which the material was guided and a mechanical chain block and weights that pushed the rod forward were used. There was no hydrostatic guide on these models. Later, the mechanical chain hoist was replaced by a motor-driven chain hoist or hydraulics , thus moving the pushrod. In addition, the hydrostatic guidance was added here, in that the channels were flooded with oil. The next stage of development was the automated reloading of the material. It is now possible to place several bars of material on a shelf and move them from there into the guide channel. This significantly reduced the reload times. Over the years, these devices have become more and more complex in structure and possible applications. This resulted from stricter laws and regulations, as well as the steadily increasing demands on such devices from the user .
Short loading magazine
technology
In the case of short loading magazines (example image 2), the material is moved from the so-called material tray onto a loading channel. From there it is fed into the lathe spindle with the help of a "flag". The material is then pushed against a stop with the aid of the slide or moved into position. In this variant, the feed rod does not have a collet . This is not necessary because the short loader does not take on any leading task, but is only responsible for tracking the material. Because of this fact, the material or rod length is limited to the spindle length. You can remedy this with a spindle extension. Here, the spindle is "artificially" extended with the help of a device. (Sample image 3)
Advantages and disadvantages
- The advantages of these magazines are, on the one hand, the reduction of the loads (in contrast to material from 3 m) on the spindle, which results from the additional mass of the material.
- Likewise, no auxiliary material is required here to guide the material, since the material is only guided by the spindle of the CNC lathe.
- This fact means that higher speeds can also be used during machining .
- This enables faster machining of the workpiece .
- But the result can also be an improvement in the surface to be worked on and less space required.
- The disadvantage is that the length of the material is limited to the spindle.
- The material also usually has to be sawn to the appropriate maximum length.
history
The first short loader was brought onto the market in 1986 by SAMECA SA. These loading magazines were fully pneumatic. This means that the bar feed and the reloading of the bars from the material tray to the feed channel was done by pneumatic cylinders. Due to the poor control of the pneumatic cylinders and the costs, this technology was replaced by a fully electric version from 1997. Here were servomotors used for the feed and reloading. Here too, SAMECA SA was a pioneer. The advantage was and is primarily the possibility to position the material freely without using a stop. With these models, however, a manual adjustment of the rod diameter towards the center of the spindle was always necessary. Nowadays there are also loading magazines that have automated these settings. This reduces the set-up time for these automation devices.
Special loader
Special loaders are used to guide and move unusual material shapes or extremely long bars. There are different techniques that are used depending on the material.
Bar gripper
Another way to move a bar is with a bar gripper . The bar gripper is a tool attached to the turret . This tool clamps the material with two "fingers". With the help of the z-axis , the rod is then pulled into position when the chuck is open.
example Pictures
1. Loading magazine for 3 m bars
2. Short loading magazine
3. Short loader and spindle extension
4. Charging cycle of a short charger
5. Scheme of spindle extension and spindle
