Among turning/milling machines there is a B-axis machine tool, which is a lathe that includes 5-coordinate milling capabilities. Obtaining a B-axis machine tool requires both a large financial investment and a lot of time. Compared with a turning/milling machine with similar functions without a B-axis configuration, the price of a machine tool with a B-axis is nearly 20% higher. However, for shops that can benefit from B-axis machining, the productivity gains provided by B-axis machines make the investment well worth it.

Basic principles of B-axis

Methods Machine Tools Inc., a machine tool importer and exclusive distributor of Nakamura-Tome machine tools in the United States, frequently discusses the fundamentals of B-axis machines with potential buyers to ensure they fully understand the machine’s capabilities. ability. Methods tells its potential customers this standard definition: B-axis machines combine the turning capabilities of a horizontal/vertical lathe with the milling and machining capabilities of a 5-coordinate machining center.

Like traditional turning/milling machines, B-axis machines are equipped with Z-X (turning) and C (rotary milling) axis controls. The B-spindle head is used as a milling spindle or turning/boring tool holder, allowing the machine to perform all milling and turning operations in a single setup. These machines can also control the Y-axis for eccentric milling operations. But it’s the B-axis functionality that sets these machines apart from the rest. The B-axis is defined as rotating around the Y-axis, and the positioning of this fifth coordinate axis enables compound angle machining. The B-axis function enables the machine tool to fully support 5-axis indexing milling and 3D/5-axis linked free-form milling.

Entire part, single clamping

B-axis machines improve part accuracy because they maintain higher tolerances between turned and milled features. For example, when machining a tool body on a B-axis machine, it is very easy to maintain geometric tolerances between milling and turning operations. As with traditional turn/mill machines, errors caused by changing parts from lathe to mill are eliminated with a single setup. For parts that require turning and multi-axis milling operations that only a B-axis machine can complete, it is especially important to use smaller tolerances between multiple datums to maintain geometric tolerances between individual features.

If equipped with dual spindles, the extended machining range of a B-axis machine allows it to perform turning and milling operations both in front of and behind the workpiece. Each spindle (main spindle and sub-spindle) plays a workpiece clamping role, so that five-coordinate linkage cutting can be performed in front or behind the part, so that the entire part can be processed in one clamping. Workpieces that previously required four clampings (front turning, rear turning, front milling, and rear milling) can be reduced to one clamping on a machine tool with B-axis function.

Multi-spindle B-axis machines equipped with a lower turret further improve part machining capabilities in a single setup. Referring to Figure 1, in this configuration, when other turret tools are operating on the opposing spindle, the B-axis head can operate simultaneously, so synchronized linkage operation is possible. In other words, cutting can be performed simultaneously on the front and rear of the part.

Additionally, shops have to consider “unexpected” parts that don’t necessarily have B-axis features (complex angles and/or features on multiple faces) but still require milling and turning. For example, a company may machine a subset of hydraulic parts that require B-axis machining, but find that the majority of the workpiece requires both traditional milling and turning. For this kind of factory, purchasing a B-axis machine tool can meet all the turning/milling needs.

Simplify programming

Once a company determines that B-axis machines meet its needs and part production needs, the main issue is ensuring that CNC programmers have the CAM tools to program these machines. Effective CAM software enables shops to take full advantage of the capabilities of B-axis machines by providing tools to efficiently generate, optimize and verify CNC programs. Observing a B-axis machine in operation (especially for the first time) can be very intimidating – its complex configuration, simultaneous machining, and non-perpendicular multi-axis tool motion can be intimidating. Therefore, the CAM system must give the programmer complete control over all movements of the machine tool. This control simplifies the challenges of programming such complex machine tools, and the availability of this software could encourage more shops to consider the productivity benefits of this equipment.

When CAM software development company DP Technology began researching the problem of programming workpieces on B-axis machine tools, it realized that a system with a fully integrated mill/turn programming environment could simplify the programming of these machine tools and provide major shops with access to B-axis machines. The flexibility needed for efficient and precise programming of shaft parts. Basically, an integrated programming environment means that shops don’t have to do the turning part of the part in one software application and the milling part of the part in another, and then try to coordinate them efficiently.

To this end, the company developed the Esprit SolidMillTurn product. The software was released in March 2003 and provides a 2- to 5-axis milling processing cycle suite, including 3-axis and 5-axis linkage 3-dimensional multi-face/integral machining. It also supports turning cycles such as facing, boring, grooving, and threading. . The program is highly flexible and the programmer can use milling and turning cycles on a single workpiece in any combination – in front of or behind the part, on the main and secondary spindles, with an upper B-axis head or a lower turret, etc.

As part of this software, a programming tool that is particularly important for B-axis machine tools is the “work plane”. Each part feature is automatically assigned to the most appropriate “work plane,” simplifying part programming operations for B-axis machining. The “working plane” defines the positioning of the C and B axes, simplifying drilling and milling features located on compound angles (B-axis features). See Figure 3. For example, in order to drill a hole at a certain angle, instead of programming linked X and Z axes, the programmer can use a “working plane” to define the angle of the C and B axes, thereby automatically rotating the Z-X coordinate system and only requiring the programmer to specify a single Z Just move the axis. In effect, the machine tool will move the X and Y axes to machine the hole. A “work plane” allows the user to set up a “local coordinate system”, simplifying the G-code used to generate a given feature and making it easier for the operator to understand.

Software tools that synchronize and optimize machining processes through a single interface are useful for organizing turning/milling programs. DP Technology believes that an effective synchronization tool can fully integrate all machining, not only providing a combined display window listing milling and turning operations and their associated cycle times, but also adapting the view to meet the rotation supported by the machine tool. Number of towers, machining heads or spindles required. Logically, this simplifies programming by requiring the user to figure out how the part will be machined in one place.

In B-axis machining, the combination of man-hour research that automatically calculates cycle time and comprehensive tool simulation and verification functions is of great significance in B-axis machining, where tool breakage is always a concern for factories. Shops using B-axis machines will find it extremely useful to be able to program a sequence of milling and turning operations, optimize cycle times, and simulate these operations at any point in the programming process to verify that there is no tool collision.

In order to effectively verify CNC programs, it is of great significance if the simulation is exactly similar to the operation of the machine tool. For example, Esprit’s Machine Setup provides an interface where each shop can define the configuration and number of turrets and spindles for their specific machine tools to ensure accurate simulation. Additionally, to provide efficient programming of B-axis machining, this CAM system displays the entire part on the screen along with the key moving parts of the machine tool (spindle, turret, B-axis head, tooling) rather than just part parts to prevent potential Tool collision accidents occur, especially during simultaneous machining or when transferring parts from the main spindle to the secondary spindle. See Figure 4. Once the tool paths are generated and verified, the postprocessor forms G-code programs for all milling and turning operations. This is a significant advantage over software that requires users to post-process turning and milling toolpaths separately and then merge them into a single program for download to the shop floor.

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