Vertical and Horizontal Conversion Machining Center
In recent years, the advantage of being able to continuously process a pentahedron after one-stage conversion has made machining centers that can be installed once very popular among users. Our factory has successfully developed a machining center capable of automatically switching between vertical and horizontal positions, as well as a manually convertible CNC milling machine. These types of machines, including five-sided gantry machining centers, require changes in the machine coordinate system when transitioning between vertical and horizontal modes. This transition can cause some challenges during programming, especially in fine boring operations using G76 or G87 commands.
Figure 1 shows the general layout of the machine before it leaves the factory, with the machine coordinates set to horizontal. The FANUC 0MC control system used in these machines does not support automatic coordinate conversion, so when the machine is switched to vertical mode, the tool feed must shift from the Z-axis to the Y-axis. During G76 and G87 boring cycles, there is an automatic spindle orientation and retraction action. Since the machine must remain in horizontal mode during automatic tool changes, the spindle orientation is aligned parallel to the X-axis. As a result, the orientation position remains unchanged regardless of the machine's mode. However, the retraction direction depends on the selected machining plane (G17, G18, G19), which is controlled by parameter 0002.
The setting table for parameter 0002 is as follows:
| PMXY2 | PMXY1 | G17 | G18 | G19 |
|-------|-------|---------|---------|---------|
| 0 | 0 | +X | +Z | +Y |
| 0 | 1 | -X | -Z | -Y |
| 1 | 0 | +Y | +X | +Z |
| 1 | 1 | -Y | -X | -Z |
Before shipment, PMXY2 and PMXY1 are both set to 0. In horizontal machining, when executing G17G76 (or G87), the Z-axis is used for hole machining, and the retraction direction is along the X-axis, as shown in Figure 3a. The machine operates normally in this mode. However, when the machine is switched to vertical mode and G18G76 (or G87) is executed, the hole machining direction shifts to the Y-axis, and the machining plane becomes XZ (G18). According to the default settings, the retraction direction in G18 mode is +Z, which may cause the tool tip to collide with the hole wall, as illustrated in Figure 3b.
To resolve this issue, PMXY2 and PMXY1 should be set to 1 and 0, respectively, in vertical mode. This would ensure the retraction direction matches that of the horizontal mode, preventing collisions. However, manually adjusting these parameters after each conversion is inconvenient and reduces the efficiency of automated processing. To address this, the G10 command can be used to programmatically modify the values of PMXY2 and PMXY1, allowing the machine to switch automatically without manual intervention.
The following subroutines demonstrate how to implement this:
Subroutine O9020: (Transition from vertical to horizontal)
G10 L50
N0002 P××OO××××P××10××××
G11
M72
M99
Subroutine O9021: (Transition from horizontal to vertical)
G10 L50
N0002 P××10××××P××OO××××
G11
M71
M99
Here, G10 L50 enables programmable parameter input, G11 cancels it, M71 switches the machine to vertical mode, and M72 returns it to horizontal. The “׆symbol indicates that the original parameter value remains unchanged.
To simplify usage, you can set parameter P0220 to 74 and P0221 to 73. This allows you to call subroutines O9020 and O9021 using M73 and M74 directly within your program.
Important notes:
- Ensure that bit FXY in parameter P0057 is set to 1; otherwise, the hole machining will always use the Z-axis.
- Set TLCD in parameter P0019 to 1 and select tool length compensation C.
- For other fixed cycles besides rigid tapping, use plane specification to achieve proper hole machining.
This approach can also be applied to five-faced gantry machines by creating corresponding subroutines based on the same logic.
Jiangsu Bailite Transmission Technology Co., Ltd , https://www.zsindustrialbelt.com